WorldWideScience

Sample records for network access provider

  1. Secret Shoppers Find Access To Providers And Network Accuracy Lacking For Those In Marketplace And Commercial Plans.

    Science.gov (United States)

    Haeder, Simon F; Weimer, David L; Mukamel, Dana B

    2016-07-01

    The adequacy of provider networks for plans sold through insurance Marketplaces established under the Affordable Care Act has received much scrutiny recently. Various studies have established that networks are generally narrow. To learn more about network adequacy and access to care, we investigated two questions. First, no matter the nominal size of a network, can patients gain access to primary care services from providers of their choice in a timely manner? Second, how does access compare to plans sold outside insurance Marketplaces? We conducted a "secret shopper" survey of 743 primary care providers from five of California's nineteen insurance Marketplace pricing regions in the summer of 2015. Our findings indicate that obtaining access to primary care providers was generally equally challenging both inside and outside insurance Marketplaces. In less than 30 percent of cases were consumers able to schedule an appointment with an initially selected physician provider. Information about provider networks was often inaccurate. Problems accessing services for patients with acute conditions were particularly troubling. Effectively addressing issues of network adequacy requires more accurate provider information. Project HOPE—The People-to-People Health Foundation, Inc.

  2. Optical Access Networks

    Science.gov (United States)

    Zheng, Jun; Ansari, Nirwan

    2005-06-01

    Call for Papers: Optical Access Networks With the wide deployment of fiber-optic technology over the past two decades, we have witnessed a tremendous growth of bandwidth capacity in the backbone networks of today's telecommunications infrastructure. However, access networks, which cover the "last-mile" areas and serve numerous residential and small business users, have not been scaled up commensurately. The local subscriber lines for telephone and cable television are still using twisted pairs and coaxial cables. Most residential connections to the Internet are still through dial-up modems operating at a low speed on twisted pairs. As the demand for access bandwidth increases with emerging high-bandwidth applications, such as distance learning, high-definition television (HDTV), and video on demand (VoD), the last-mile access networks have become a bandwidth bottleneck in today's telecommunications infrastructure. To ease this bottleneck, it is imperative to provide sufficient bandwidth capacity in the access networks to open the bottleneck and thus present more opportunities for the provisioning of multiservices. Optical access solutions promise huge bandwidth to service providers and low-cost high-bandwidth services to end users and are therefore widely considered the technology of choice for next-generation access networks. To realize the vision of optical access networks, however, many key issues still need to be addressed, such as network architectures, signaling protocols, and implementation standards. The major challenges lie in the fact that an optical solution must be not only robust, scalable, and flexible, but also implemented at a low cost comparable to that of existing access solutions in order to increase the economic viability of many potential high-bandwidth applications. In recent years, optical access networks have been receiving tremendous attention from both academia and industry. A large number of research activities have been carried out or

  3. Evolution of Network Access Points (NAPs and agreements among Internet Service Providers (ISPs in South America

    Directory of Open Access Journals (Sweden)

    Fernando Beltrán

    2006-05-01

    Full Text Available Este artículo presenta los aspectos principales del desarrollo histórico y de asuntos actuales en el mercado suramericano de acceso a Internet: los acuerdos de interconexión para el intercambio de tráfico local y regional en Suramérica, los incentivos que tienen los proveedores de acceso a Internet para mantener o modificar la naturaleza de los acuerdos y los métodos de recuperación de costos en los puntos de intercambio de tráfico. El artículo también identifica algunas amenazas a la estabilidad de los puntos de intercambio de tráfico y las ilustra con dos casos. / This paper presents the main aspects of the historical development and the current issues at stake in the South American Internet access market: the interconnection schemes for the exchange of local and regional traffic in the South American region, the incentives Internet access providers have for keeping or modifying the nature of the agreements, and the cost recovery methods at the traffic exchange points. Some threats to the stability of the scheme for domestic traffic exchange adopted throughout the region are also identified and subsequently illustrated with country-cases.

  4. Optical Access Networks

    Science.gov (United States)

    Zheng, Jun; Ansari, Nirwan

    2005-01-01

    Call for Papers: Optical Access Networks Guest Editors Jun Zheng, University of Ottawa Nirwan Ansari, New Jersey Institute of Technology Submission Deadline: 1 June 2005 Background With the wide deployment of fiber-optic technology over the past two decades, we have witnessed a tremendous growth of bandwidth capacity in the backbone networks of today's telecommunications infrastructure. However, access networks, which cover the "last-mile" areas and serve numerous residential and small business users, have not been scaled up commensurately. The local subscriber lines for telephone and cable television are still using twisted pairs and coaxial cables. Most residential connections to the Internet are still through dial-up modems operating at a low speed on twisted pairs. As the demand for access bandwidth increases with emerging high-bandwidth applications, such as distance learning, high-definition television (HDTV), and video on demand (VoD), the last-mile access networks have become a bandwidth bottleneck in today's telecommunications infrastructure. To ease this bottleneck, it is imperative to provide sufficient bandwidth capacity in the access networks to open the bottleneck and thus present more opportunities for the provisioning of multiservices. Optical access solutions promise huge bandwidth to service providers and low-cost high-bandwidth services to end users and are therefore widely considered the technology of choice for next-generation access networks. To realize the vision of optical access networks, however, many key issues still need to be addressed, such as network architectures, signaling protocols, and implementation standards. The major challenges lie in the fact that an optical solution must be not only robust, scalable, and flexible, but also implemented at a low cost comparable to that of existing access solutions in order to increase the economic viability of many potential high-bandwidth applications. In recent years, optical access networks

  5. Fixed Access Network Sharing

    Science.gov (United States)

    Cornaglia, Bruno; Young, Gavin; Marchetta, Antonio

    2015-12-01

    Fixed broadband network deployments are moving inexorably to the use of Next Generation Access (NGA) technologies and architectures. These NGA deployments involve building fiber infrastructure increasingly closer to the customer in order to increase the proportion of fiber on the customer's access connection (Fibre-To-The-Home/Building/Door/Cabinet… i.e. FTTx). This increases the speed of services that can be sold and will be increasingly required to meet the demands of new generations of video services as we evolve from HDTV to "Ultra-HD TV" with 4k and 8k lines of video resolution. However, building fiber access networks is a costly endeavor. It requires significant capital in order to cover any significant geographic coverage. Hence many companies are forming partnerships and joint-ventures in order to share the NGA network construction costs. One form of such a partnership involves two companies agreeing to each build to cover a certain geographic area and then "cross-selling" NGA products to each other in order to access customers within their partner's footprint (NGA coverage area). This is tantamount to a bi-lateral wholesale partnership. The concept of Fixed Access Network Sharing (FANS) is to address the possibility of sharing infrastructure with a high degree of flexibility for all network operators involved. By providing greater configuration control over the NGA network infrastructure, the service provider has a greater ability to define the network and hence to define their product capabilities at the active layer. This gives the service provider partners greater product development autonomy plus the ability to differentiate from each other at the active network layer.

  6. Tradeoff between User Quality-Of-Experience and Service Provider Profit in 5G Cloud Radio Access Network

    Directory of Open Access Journals (Sweden)

    Mahbuba Afrin

    2017-11-01

    Full Text Available In recent years, the Cloud Radio Access Network (CRAN has become a promising solution for increasing network capacity in terms of high data rates and low latencies for fifth-generation (5G cellular networks. In CRAN, the traditional base stations (BSs are decoupled into remote radio heads (RRHs and base band units (BBUs that are respectively responsible for radio and baseband functionalities. The RRHs are geographically proximated whereas the the BBUs are pooled in a centralized cloud named BBU pool. This virtualized architecture facilitates the system to offer high computation and communication loads from the impetuous rise of mobile devices and applications. Heterogeneous service requests from the devices to different RRHs are now sent to the BBUs to process centrally. Meeting the baseband processing of heterogeneous requests while keeping their Quality-of-Service (QoS requirements with the limited computational resources as well as enhancing service provider profit is a challenging multi-constraint problem. In this work, a multi-objective non-linear programming solution to the Quality-of-Experience (QoE and Profit-aware Resource Allocation problem is developed which makes a trade-off in between the two. Two computationally viable scheduling algorithms, named First Fit Satisfaction and First Fit Profit algorithms, are developed to focus on maximization of user QoE and profit, respectively, while keeping the minimum requirement level for the other one. The simulation environment is built on a relevant simulation toolkit. The experimental results demonstrate that the proposed system outperforms state-of-the-art works well across the requests QoS, average waiting time, user QoE, and service provider profit.

  7. Remote Network Access (RNA)

    National Research Council Canada - National Science Library

    2002-01-01

    .... Remote Network Access (RNA) includes or is associated with all communication devices/software, firewalls, intrusion detection systems and virus protection applications to ensure security of the OIG, DoD, Network from remote...

  8. Editorial: Next Generation Access Networks

    Science.gov (United States)

    Ruffini, Marco; Cincotti, Gabriella; Pizzinat, Anna; Vetter, Peter

    2015-12-01

    Over the past decade we have seen an increasing number of operators deploying Fibre-to-the-home (FTTH) solutions in access networks, in order to provide home users with a much needed network access upgrade, to support higher peak rates, higher sustained rates and a better and more uniform broadband coverage of the territory.

  9. Medical service provider networks.

    Science.gov (United States)

    Mougeot, Michel; Naegelen, Florence

    2018-05-17

    In many countries, health insurers or health plans choose to contract either with any willing providers or with preferred providers. We compare these mechanisms when two medical services are imperfect substitutes in demand and are supplied by two different firms. In both cases, the reimbursement is higher when patients select the in-network provider(s). We show that these mechanisms yield lower prices, lower providers' and insurer's profits, and lower expense than in the uniform-reimbursement case. Whatever the degree of product differentiation, a not-for-profit insurer should prefer selective contracting and select a reimbursement such that the out-of-pocket expense is null. Although all providers join the network under any-willing-provider contracting in the absence of third-party payment, an asymmetric equilibrium may exist when this billing arrangement is implemented. Copyright © 2018 John Wiley & Sons, Ltd.

  10. Wireless Multi Hop Access Networks and Protocols

    OpenAIRE

    Nilsson Plymoth, Anders

    2007-01-01

    As more and more applications and services in our society now depend on the Internet, it is important that dynamically deployed wireless multi hop networks are able to gain access to the Internet and other infrastructure networks and services. This thesis proposes and evaluates solutions for providing multi hop Internet Access. It investigates how ad hoc networks can be combined with wireless and mesh networks in order to create wireless multi hop access networks. When several access points t...

  11. Optical Subsystems for Next Generation Access Networks

    DEFF Research Database (Denmark)

    Lazaro, J.A; Polo, V.; Schrenk, B.

    2011-01-01

    Recent optical technologies are providing higher flexibility to next generation access networks: on the one hand, providing progressive FTTx and specifically FTTH deployment, progressively shortening the copper access network; on the other hand, also opening fixed-mobile convergence solutions...... in next generation PON architectures. It is provided an overview of the optical subsystems developed for the implementation of the proposed NG-Access Networks....

  12. Software defined access networks

    OpenAIRE

    Maricato, José Miguel Duarte

    2016-01-01

    With the increase of internet usage and the exponential growth of bandwidth consumption due to the increasing number of users of new generation equipments and the creation of new services that consume increasingly higher bandwidths, it's necessary to nd solutions to meet these new requirements. Passive optical networks (PONs) promise to solve these problems by providing a better service to users and providers. PON networks are very attractive since they don't depend on a...

  13. Network Access Control For Dummies

    CERN Document Server

    Kelley, Jay; Wessels, Denzil

    2009-01-01

    Network access control (NAC) is how you manage network security when your employees, partners, and guests need to access your network using laptops and mobile devices. Network Access Control For Dummies is where you learn how NAC works, how to implement a program, and how to take real-world challenges in stride. You'll learn how to deploy and maintain NAC in your environment, identify and apply NAC standards, and extend NAC for greater network security. Along the way you'll become familiar with what NAC is (and what it isn't) as well as the key business drivers for deploying NAC.Learn the step

  14. Bring Your Own Device - Providing Reliable Model of Data Access

    Directory of Open Access Journals (Sweden)

    Stąpór Paweł

    2016-10-01

    Full Text Available The article presents a model of Bring Your Own Device (BYOD as a model network, which provides the user reliable access to network resources. BYOD is a model dynamically developing, which can be applied in many areas. Research network has been launched in order to carry out the test, in which as a service of BYOD model Work Folders service was used. This service allows the user to synchronize files between the device and the server. An access to the network is completed through the wireless communication by the 802.11n standard. Obtained results are shown and analyzed in this article.

  15. Distributed medium access control in wireless networks

    CERN Document Server

    Wang, Ping

    2013-01-01

    This brief investigates distributed medium access control (MAC) with QoS provisioning for both single- and multi-hop wireless networks including wireless local area networks (WLANs), wireless ad hoc networks, and wireless mesh networks. For WLANs, an efficient MAC scheme and a call admission control algorithm are presented to provide guaranteed QoS for voice traffic and, at the same time, increase the voice capacity significantly compared with the current WLAN standard. In addition, a novel token-based scheduling scheme is proposed to provide great flexibility and facility to the network servi

  16. Accessing ANSA Objects from OSI Network Management

    OpenAIRE

    Berrah, Karrim; Gay, David; Genilloud, Guy

    1994-01-01

    OSI network management provides a general framework for the management of OSI systems, and by extension of any distributed system. However, it is not yet possible to tell to what extent the tools developed for network management will be applicable to distributed systems management. This paper assumes that network managers will want to have some control of the distributed infrastructure and applications. It examines how access to some of the ANSA management interfaces can be given to OSI netwo...

  17. Browsing for the Best Internet Access Provider?

    Science.gov (United States)

    Weil, Marty

    1996-01-01

    Highlights points to consider when choosing an Internet Service Provider. Serial Line Internet Protocol (SLIP) and Point to Point Protocol (PPP) are compared regarding price, performance, bandwidth, speed, and technical support. Obtaining access via local, national, consumer online, and telephone-company providers is discussed. A pricing chart and…

  18. Designing Broadband Access Networks with Triple Redundancy

    DEFF Research Database (Denmark)

    Pedersen, Jens Myrup; Riaz, Muhammad Tahir; Knudsen, Thomas Phillip

    2005-01-01

    An architecture is proposed for designing broadband access networks, which offer triple redundancy to the end users, resulting in networks providing connectivity even in case of any two independent node or line failures. Two physically independent connections are offered by fiber, and the last...... provided by some wireless solution. Based on experience with planning Fiber To The Home, the architecture is designed to meet a number of demands, making it practicable and useful in realworld network planning. The proposed wired topology is planar, and suitable for being fitted onto the road network...

  19. Planning Multitechnology Access Networks with Performance Constraints

    Science.gov (United States)

    Chamberland, Steven

    Considering the number of access network technologies and the investment needed for the “last mile” of a solution, in today’s highly competitive markets, planning tools are crucial for the service providers to optimize the network costs and accelerate the planning process. In this paper, we propose to tackle the problem of planning access networks composed of four technologies/architectures: the digital subscriber line (xDSL) technologies deployed directly from the central office (CO), the fiber-to-the-node (FTTN), the fiber-to-the-micro-node (FTTn) and the fiber-to-the-premises (FTTP). A mathematical programming model is proposed for this planning problem that is solved using a commercial implementation of the branch-and-bound algorithm. Next, a detailed access network planning example is presented followed by a systematic set of experiments designed to assess the performance of the proposed approach.

  20. Research on optical access network remote management technology

    Science.gov (United States)

    Wang, Wayne; Zou, Chen; Luo, Wenyi

    2008-11-01

    This paper goal is to provide a framework for the remote configuration and management of services for PON (Passive Optical Network) access and fiber access. Also it defines how Auto-Configuration Servers (ACS) in the network can remotely configure, troubleshoot and manage a Passive Optical Network (PON) optical network termination (ONT) with layer 3 capabilities using the CPE WAN management protocol, TR-069.

  1. Efficient Access Control in Multimedia Social Networks

    Science.gov (United States)

    Sachan, Amit; Emmanuel, Sabu

    Multimedia social networks (MMSNs) have provided a convenient way to share multimedia contents such as images, videos, blogs, etc. Contents shared by a person can be easily accessed by anybody else over the Internet. However, due to various privacy, security, and legal concerns people often want to selectively share the contents only with their friends, family, colleagues, etc. Access control mechanisms play an important role in this situation. With access control mechanisms one can decide the persons who can access a shared content and who cannot. But continuously growing content uploads and accesses, fine grained access control requirements (e.g. different access control parameters for different parts in a picture), and specific access control requirements for multimedia contents can make the time complexity of access control to be very large. So, it is important to study an efficient access control mechanism suitable for MMSNs. In this chapter we present an efficient bit-vector transform based access control mechanism for MMSNs. The proposed approach is also compatible with other requirements of MMSNs, such as access rights modification, content deletion, etc. Mathematical analysis and experimental results show the effectiveness and efficiency of our proposed approach.

  2. Network performance and fault analytics for LTE wireless service providers

    CERN Document Server

    Kakadia, Deepak; Gilgur, Alexander

    2017-01-01

     This book is intended to describe how to leverage emerging technologies big data analytics and SDN, to address challenges specific to LTE and IP network performance and fault management data in order to more efficiently manage and operate an LTE wireless networks. The proposed integrated solutions permit the LTE network service provider to operate entire integrated network, from RAN to Core , from UE to application service, as one unified system and correspondingly collect and align disparate key metrics and data, using an integrated and holistic approach to network analysis. The LTE wireless network performance and fault involves the network performance and management of network elements in EUTRAN, EPC and IP transport components, not only as individual components, but also as nuances of inter-working of these components. The key metrics for EUTRAN include radio access network accessibility, retainability, integrity, availability and mobility. The key metrics for EPC include MME accessibility, mobility and...

  3. Providing Data Access for Interdisciplinary Research

    Science.gov (United States)

    Hooper, R. P.; Couch, A.

    2012-12-01

    Developing an interdisciplinary understanding of human and environmental interactions with water requires access to a variety of data kinds collected by various organizations. The CUAHSI Hydrologic Information System (HIS) is a standards-based, services-oriented architecture designed for time-series data. Such data represents an important type of data in water studies. Through the efforts of HIS, a standard transmission language, WaterML2, has been adopted by the Open Geospatial Consortium and is under consideration by the World Meteorologic Organization as an international standards. Web services have also been developed to retrieve data and metadata. HIS is completed with a metadata catalog, hosted by San Diego Supercomputing Center, which indexes more than 20 million time series provided from over 90 different services. This catalog is supported through a hierarchically organized controlled vocabulary that is open for community input and mediation. Data publishers include federal agencies, universities, state agencies, and non-profit organizations such as watershed associations. Accessing data from such a broad spectrum of sources through a uniform service standard promises to truly transform the way in which hydrologic research is done. CUAHSI HIS is a large-scale prototype at this time, but a proposal is under consideration by the National Science Foundation to operationalize HIS through a data facility, tentatively called the CUAHSI Water Data Center. Establishing HIS is an important step to enable research into human-environment interactions with water, but it is only one step. Other data structures will need to be made accessible and interoperable to support this research. Some data—such as two-dimensional GIS coverages—already have widely used standards for transmission and sharing. The US Federal government has long operated a clearinghouse for federal geographic data that is now being augmented with other services such as ArcGIS OnLine. Other data

  4. Virtual Library: Providing Accessible Online Resources.

    Science.gov (United States)

    Kelly, Rob

    2001-01-01

    Describes e-global library, a virtual library based on the Jones International University's library that organizes Internet resources to make them more accessible to students at all skill levels. Highlights include online tutorials; research guides; financial aid and career development information; and possible partnerships with other digital…

  5. Approximate Networking for Universal Internet Access

    Directory of Open Access Journals (Sweden)

    Junaid Qadir

    2017-12-01

    Full Text Available Despite the best efforts of networking researchers and practitioners, an ideal Internet experience is inaccessible to an overwhelming majority of people the world over, mainly due to the lack of cost-efficient ways of provisioning high-performance, global Internet. In this paper, we argue that instead of an exclusive focus on a utopian goal of universally accessible “ideal networking” (in which we have a high throughput and quality of service as well as low latency and congestion, we should consider providing “approximate networking” through the adoption of context-appropriate trade-offs. In this regard, we propose to leverage the advances in the emerging trend of “approximate computing” that rely on relaxing the bounds of precise/exact computing to provide new opportunities for improving the area, power, and performance efficiency of systems by orders of magnitude by embracing output errors in resilient applications. Furthermore, we propose to extend the dimensions of approximate computing towards various knobs available at network layers. Approximate networking can be used to provision “Global Access to the Internet for All” (GAIA in a pragmatically tiered fashion, in which different users around the world are provided a different context-appropriate (but still contextually functional Internet experience.

  6. Enabling Wireless Cooperation in User Provided Networks

    OpenAIRE

    Rolla, Vitor Guerra

    2015-01-01

    Tese de doutoramento em Ciências e Tecnologias da Informação, apresentada ao Departamento de Engenharia Informática da Faculdade de Ciências e Tecnologia da Universidade de Coimbra This doctoral thesis investigates user provided networks. Such networks have become important research subjects in the field of informatics engineering due to the recent popularity of smart phones. User provided networks are independent from traditional Internet service providers. Communication and informati...

  7. Location-aware network operation for cloud radio access network

    KAUST Repository

    Wang, Fanggang; Ruan, Liangzhong; Win, Moe Z.

    2017-01-01

    One of the major challenges in effectively operating a cloud radio access network (C-RAN) is the excessive overhead signaling and computation load that scale rapidly with the size of the network. In this paper, the exploitation of location

  8. Location-aware network operation for cloud radio access network

    KAUST Repository

    Wang, Fanggang

    2017-06-20

    One of the major challenges in effectively operating a cloud radio access network (C-RAN) is the excessive overhead signaling and computation load that scale rapidly with the size of the network. In this paper, the exploitation of location information of the mobile devices is proposed to address this challenge. We consider an approach in which location-assisted channel state information (CSI) acquisition methods are introduced to complement conventional pilot-based CSI acquisition methods and avoid excessive overhead signaling. A low-complexity algorithm is designed to maximize the sum rate. An adaptive algorithm is also proposed to address the uncertainty issue in CSI acquisition. Both theoretical and numerical analyses show that location information provides a new dimension to improve throughput for next-generation massive cooperative networks.

  9. Research of Ad Hoc Networks Access Algorithm

    Science.gov (United States)

    Xiang, Ma

    With the continuous development of mobile communication technology, Ad Hoc access network has become a hot research, Ad Hoc access network nodes can be used to expand capacity of multi-hop communication range of mobile communication system, even business adjacent to the community, improve edge data rates. When the ad hoc network is the access network of the internet, the gateway discovery protocol is very important to choose the most appropriate gateway to guarantee the connectivity between ad hoc network and IP based fixed networks. The paper proposes a QoS gateway discovery protocol which uses the time delay and stable route to the gateway selection conditions. And according to the gateway discovery protocol, it also proposes a fast handover scheme which can decrease the handover time and improve the handover efficiency.

  10. A Method for Upper Bounding on Network Access Speed

    DEFF Research Database (Denmark)

    Knudsen, Thomas Phillip; Patel, A.; Pedersen, Jens Myrup

    2004-01-01

    This paper presents a method for calculating an upper bound on network access speed growth and gives guidelines for further research experiments and simulations. The method is aimed at providing a basis for simulation of long term network development and resource management.......This paper presents a method for calculating an upper bound on network access speed growth and gives guidelines for further research experiments and simulations. The method is aimed at providing a basis for simulation of long term network development and resource management....

  11. Joint control algorithm in access network

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    To deal with long probing delay and inaccurate probing results in the endpoint admission control method,a joint local and end-to-end admission control algorithm is proposed,which introduces local probing of access network besides end-to-end probing.Through local probing,the algorithm accurately estimated the resource status of the access network.Simulation shows that this algorithm can improve admission control performance and reduce users' average waiting time when the access network is heavily loaded.

  12. Personalizing Access to Learning Networks

    DEFF Research Database (Denmark)

    Dolog, Peter; Simon, Bernd; Nejdl, Wolfgang

    2008-01-01

    In this article, we describe a Smart Space for Learning™ (SS4L) framework and infrastructure that enables personalized access to distributed heterogeneous knowledge repositories. Helping a learner to choose an appropriate learning resource or activity is a key problem which we address in this fra......In this article, we describe a Smart Space for Learning™ (SS4L) framework and infrastructure that enables personalized access to distributed heterogeneous knowledge repositories. Helping a learner to choose an appropriate learning resource or activity is a key problem which we address...... in this framework, enabling personalized access to federated learning repositories with a vast number of learning offers. Our infrastructure includes personalization strategies both at the query and the query results level. Query rewriting is based on learning and language preferences; rule-based and ranking...

  13. Sierra Stars Observatory Network: An Accessible Global Network

    Science.gov (United States)

    Williams, Richard; Beshore, Edward

    2011-03-01

    The Sierra Stars Observatory Network (SSON) is a unique partnership among professional observatories that provides its users with affordable high-quality calibrated image data. SSON comprises observatories in the Northern and Southern Hemisphere and is in the process of expanding to a truly global network capable of covering the entire sky 24 hours a day in the near future. The goal of SSON is to serve the needs of science-based projects and programs. Colleges, universities, institutions, and individuals use SSON for their education and research projects. The mission of SSON is to promote and expand the use of its facilities among the thousands of colleges and schools worldwide that do not have access to professional-quality automated observatory systems to use for astronomy education and research. With appropriate leadership and guidance educators can use SSON to help teach astronomy and do meaningful scientific projects. The relatively small cost of using SSON for this type of work makes it affordable and accessible for educators to start using immediately. Remote observatory services like SSON need to evolve to better support education and research initiatives of colleges, institutions and individual investigators. To meet these needs, SSON is developing a sophisticated interactive scheduling system to integrate among the nodes of the observatory network. This will enable more dynamic observations, including immediate priority interrupts, acquiring moving objects using ephemeris data, and more.

  14. Optimizing the next generation optical access networks

    DEFF Research Database (Denmark)

    Amaya Fernández, Ferney Orlando; Soto, Ana Cardenas; Tafur Monroy, Idelfonso

    2009-01-01

    Several issues in the design and optimization of the next generation optical access network (NG-OAN) are presented. The noise, the distortion and the fiber optic nonlinearities are considered to optimize the video distribution link in a passive optical network (PON). A discussion of the effect...

  15. Multiple-Access Quantum-Classical Networks

    Science.gov (United States)

    Razavi, Mohsen

    2011-10-01

    A multi-user network that supports both classical and quantum communication is proposed. By relying on optical code-division multiple access techniques, this system offers simultaneous key exchange between multiple pairs of network users. A lower bound on the secure key generation rate will be derived for decoy-state quantum key distribution protocols.

  16. Achieving universal access to next generation networks

    DEFF Research Database (Denmark)

    Falch, Morten; Henten, Anders

    The paper examines investment dimensions of next generation networks in a universal service perspective in a European context. The question is how new network infrastructures for getting access to communication, information and entertainment services in the present and future information society...

  17. Optical label-controlled transparent metro-access network interface

    DEFF Research Database (Denmark)

    Osadchiy, Alexey Vladimirovich

    This thesis presents results obtained during the course of my PhD research on optical signal routing and interfacing between the metropolitan and access segments of optical networks. Due to both increasing capacity demands and variety of emerging services types, new technological challenges...... control. Highlights of my research include my proposal and experimental proof of principle of an optical coherent detection based optical access network architecture providing support for a large number of users over a single distribution fiber; a spectral amplitude encoded label detection technique...... are arising for seamlessly interfacing metropolitan and access networks. Therefore, in this PhD project, I have analyzed those technological challenges and identified the key aspects to be addressed. I have also proposed and experimentally verified a number of solutions to metropolitan and access networks...

  18. Survey on Cloud Radio Access Network

    Directory of Open Access Journals (Sweden)

    Reeta Chhatani

    2016-01-01

    Full Text Available The existing wireless network will face the challenge of data tsunami in the near future. Densification of network will deal huge data traffic but will increase the interferences and network cost. At the same time, the existing wireless network is underutilized due to dynamic traffic. To deal with this adverse scenario, a change in the current network architecture is required. Based on virtualization, Cloud Radio Access Network (CRAN was proposed for wireless network. In CRAN the functionality of base station will be distributed into base band unit (BBU and remote radio heads (RRH which will achieve benefits of centralization. This paper presents a survey on CRAN centring on optimized resource allocation, energy efficiency and throughput maximization under fronthaul capacity. The existing solution and future opportunities in CRAN are also summarized.

  19. IP access networks with QoS support

    Science.gov (United States)

    Sargento, Susana; Valadas, Rui J. M. T.; Goncalves, Jorge; Sousa, Henrique

    2001-07-01

    The increasing demand of new services and applications is pushing for drastic changes on the design of access networks targeted mainly for residential and SOHO users. Future access networks will provide full service integration (including multimedia), resource sharing at the packet level and QoS support. It is expected that using IP as the base technology, the ideal plug-and-play scenario, where the management actions of the access network operator are kept to a minimum, will be achieved easily. This paper proposes an architecture for access networks based on layer 2 or layer 3 multiplexers that allows a number of simplifications in the network elements and protocols (e.g. in the routing and addressing functions). We discuss two possible steps in the evolution of access networks towards a more efficient support of IP based services. The first one still provides no QoS support and was designed with the goal of reusing as much as possible current technologies; it is based on tunneling to transport PPP sessions. The second one introduces QoS support through the use of emerging technologies and protocols. We illustrate the different phases of a multimedia Internet access session, when using SIP for session initiation, COPS for the management of QoS policies including the AAA functions and RSVP for resource reservation.

  20. Providing QoS guarantee in 3G wireless networks

    Science.gov (United States)

    Chuah, MooiChoo; Huang, Min; Kumar, Suresh

    2001-07-01

    The third generation networks and services present opportunities to offer multimedia applications and services that meet end-to-end quality of service requirements. In this article, we present UMTS QoS architecture and its requirements. This includes the definition of QoS parameters, traffic classes, the end-to-end data delivery model, and the mapping of end-to-end services to the services provided by the network elements of the UMTS. End-to-end QoS of a user flow is achieved by the combination of the QoS control over UMTS Domain and the IP core Network. In the Third Generation Wireless network, UMTS bearer service manager is responsible to manage radio and transport resources to QoS-enabled applications. The UMTS bearer service consists of the Radio Access Bearer Service between Mobile Terminal and SGSN and Core Network bearer service between SGSN and GGSN. The Radio Access Bearer Service is further realized by the Radio Bearer Service (mostly air interface) and Iu bearer service. For the 3G air interface, one can provide differentiated QoS via intelligent burst allocation scheme, adaptive spreading factor control and weighted fair queueing scheduling algorithms. Next, we discuss the requirements for the transport technologies in the radio access network to provide differentiated QoS to multiple classes of traffic. We discuss both ATM based and IP based transport solutions. Last but not least, we discuss how QoS mechanism is provided in the core network to ensure e2e quality of service requirements. We discuss how mobile terminals that use RSVP as QoS signaling mechanisms can be are supported in the 3G network which may implement only IETF diffserv mechanism. . We discuss how one can map UMTS QoS classes with IETF diffserv code points. We also discuss 2G/3G handover scenarios and how the 2G/3G QoS parameters can be mapped.

  1. Scalable Lunar Surface Networks and Adaptive Orbit Access, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Innovative network architecture, protocols, and algorithms are proposed for both lunar surface networks and orbit access networks. Firstly, an overlaying...

  2. Protocol and networking design issues for local access WDM networks

    NARCIS (Netherlands)

    Salvador, M.R.; Heemstra de Groot, S.M.; Niemegeers, I.G.M.M.

    This report gives an overview of some of the protocol and networking design issues that have been addressed in Flamingo, a major ongoing project which investigates the use of WDM optical technology in local access networks. Quality of service delivery and wavelength assignment are focused on in this

  3. Protocol and networking design issues for local access WDM networks

    OpenAIRE

    Salvador, M.R.; Heemstra de Groot, S.M.; Niemegeers, I.G.M.M.

    1999-01-01

    This report gives an overview of some of the protocol and networking design issues that have been addressed in Flamingo, a major ongoing project which investigates the use of WDM optical technology in local access networks. Quality of service delivery and wavelength assignment are focused on in this report. A brief introduction to optical networks and WDM as well as a brief description of Flamingo are also included in this report.

  4. TCP Performance Enhancement for UMTS Access Network

    DEFF Research Database (Denmark)

    Hu, Liang

    2008-01-01

    is between UMTS access network and Internet. The split proxy divides the bandwidth delay product into two parts, resulting in two TCP connections with smaller bandwidth delay products. Simulation results show, the split TCP proxy can significantly improve the TCP performance under high bit rate DCH channel......We aim at optimize the TCP performance over UMTS access network challenged by the large delay bandwidth product that is mainly caused by the latency from the link layer ARQ retransmissions and diversity technique at physical layer. We propose to place a split TCP proxy at GGSN nodes which...

  5. Energy efficiency for cloud-radio access networks with imperfect channel state information

    KAUST Repository

    Al-Oquibi, Bayan; Amin, Osama; Dahrouj, Hayssam; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2016-01-01

    metric in next generation wireless systems (5G). Cloud radio access network (C-RAN), a promising 5G network architecture, provides an efficient framework for improving the EE performance, by means of coordinating the transmission across the network

  6. Evaluation of Crosstalk Attacks in Access Networks

    DEFF Research Database (Denmark)

    Wagner, Christoph; Eiselt, Michael; Grobe, Klaus

    2016-01-01

    WDM-PON systems regained interest as low-cost solution for metro and access networks. We present a comparative analysis of resilience of wavelength-selective and wavelength-routed architectures against crosstalk attackers. We compare the vulnerability of these architectures against attacks...

  7. Spectrum access games for cognitive radio networks

    CSIR Research Space (South Africa)

    Masonta, MT

    2010-09-01

    Full Text Available received a wide acceptance in next generation and intelligent wireless communication systems. In this paper the authors make use of game theory approach to model and analyze cognitive radio networks in order to allow dynamic spectrum access in broadband...

  8. File access prediction using neural networks.

    Science.gov (United States)

    Patra, Prashanta Kumar; Sahu, Muktikanta; Mohapatra, Subasish; Samantray, Ronak Kumar

    2010-06-01

    One of the most vexing issues in design of a high-speed computer is the wide gap of access times between the memory and the disk. To solve this problem, static file access predictors have been used. In this paper, we propose dynamic file access predictors using neural networks to significantly improve upon the accuracy, success-per-reference, and effective-success-rate-per-reference by using neural-network-based file access predictor with proper tuning. In particular, we verified that the incorrect prediction has been reduced from 53.11% to 43.63% for the proposed neural network prediction method with a standard configuration than the recent popularity (RP) method. With manual tuning for each trace, we are able to improve upon the misprediction rate and effective-success-rate-per-reference using a standard configuration. Simulations on distributed file system (DFS) traces reveal that exact fit radial basis function (RBF) gives better prediction in high end system whereas multilayer perceptron (MLP) trained with Levenberg-Marquardt (LM) backpropagation outperforms in system having good computational capability. Probabilistic and competitive predictors are the most suitable for work stations having limited resources to deal with and the former predictor is more efficient than the latter for servers having maximum system calls. Finally, we conclude that MLP with LM backpropagation algorithm has better success rate of file prediction than those of simple perceptron, last successor, stable successor, and best k out of m predictors.

  9. An access alternative for mobile satellite networks

    Science.gov (United States)

    Wu, W. W.

    1988-01-01

    Conceptually, this paper discusses strategies of digital satellite communication networks for a very large number of low density traffic stations. These stations can be either aeronautical, land mobile, or maritime. The techniques can be applied to international, domestic, regional, and special purpose satellite networks. The applications can be commercial, scientific, military, emergency, navigational or educational. The key strategy is the use of a non-orthogonal access method, which tolerates overlapping signals. With n being either time or frequency partitions, and with a single overlapping signal allowed, a low cost mobile satellite system can be designed with n squared (n squared + n + 1) number of terminals.

  10. Access to finance from different finance provider types

    NARCIS (Netherlands)

    Wulandari, Eliana; Meuwissen, Miranda P.M.; Karmana, Maman H.; Oude Lansink, Alfons G.J.M.

    2017-01-01

    Analysing farmer knowledge of the requirements of finance providers can provide valuable insights to policy makers about ways to improve farmers’ access to finance. This study compares farmer knowledge of the requirements to obtain finance with the actual requirements set by different finance

  11. Cloud Radio Access Network architecture. Towards 5G mobile networks

    DEFF Research Database (Denmark)

    Checko, Aleksandra

    Cloud Radio Access Network (C-RAN) is a novel mobile network architecture which can address a number of challenges that mobile operators face while trying to support ever-growing end-users’ needs towards 5th generation of mobile networks (5G). The main idea behind C-RAN is to split the base...... stations into radio and baseband parts, and pool the Baseband Units (BBUs) from multiple base stations into a centralized and virtualized BBU Pool. This gives a number of benefits in terms of cost and capacity. However, the challenge is then to find an optimal functionality splitting point as well...... as to design the socalled fronthaul network, interconnecting those parts. This thesis focuses on quantifying those benefits and proposing a flexible and capacity-optimized fronthaul network. It is shown that a C-RAN with a functional split resulting in a variable bit rate on the fronthaul links brings cost...

  12. Auditing Medical Records Accesses via Healthcare Interaction Networks

    Science.gov (United States)

    Chen, You; Nyemba, Steve; Malin, Bradley

    2012-01-01

    Healthcare organizations are deploying increasingly complex clinical information systems to support patient care. Traditional information security practices (e.g., role-based access control) are embedded in enterprise-level systems, but are insufficient to ensure patient privacy. This is due, in part, to the dynamic nature of healthcare, which makes it difficult to predict which care providers need access to what and when. In this paper, we show that modeling operations at a higher level of granularity (e.g., the departmental level) are stable in the context of a relational network, which may enable more effective auditing strategies. We study three months of access logs from a large academic medical center to illustrate that departmental interaction networks exhibit certain invariants, such as the number, strength, and reciprocity of relationships. We further show that the relations extracted from the network can be leveraged to assess the extent to which a patient’s care satisfies expected organizational behavior. PMID:23304277

  13. Access, fronthaul and backhaul networks for 5G and beyond

    CERN Document Server

    Imran, Muhammad Ali; Shakir, Muhammad Zeeshan

    2017-01-01

    This book provides an overview from both academic and industrial stakeholders of innovative backhaul/fronthaul solutions, covering a wide spectrum of underlying themes ranging from the recent thrust in edge caching for backhaul relaxation to mmWave based fronthauling for radio access networks.

  14. Optically transparent multiple access networks employing incoherent spectral codes

    NARCIS (Netherlands)

    Huiszoon, B.

    2008-01-01

    This Ph.D. thesis is divided into 7 chapters to provide the reader an overview of the main results achieved in di®erent sub-topics of the study towards optically transparent multiple access networks employing incoherent spectral codes taking into account wireless transmission aspects. The work

  15. A slotted access control protocol for metropolitan WDM ring networks

    Science.gov (United States)

    Baziana, P. A.; Pountourakis, I. E.

    2009-03-01

    In this study we focus on the serious scalability problems that many access protocols for WDM ring networks introduce due to the use of a dedicated wavelength per access node for either transmission or reception. We propose an efficient slotted MAC protocol suitable for WDM ring metropolitan area networks. The proposed network architecture employs a separate wavelength for control information exchange prior to the data packet transmission. Each access node is equipped with a pair of tunable transceivers for data communication and a pair of fixed tuned transceivers for control information exchange. Also, each access node includes a set of fixed delay lines for synchronization reasons; to keep the data packets, while the control information is processed. An efficient access algorithm is applied to avoid both the data wavelengths and the receiver collisions. In our protocol, each access node is capable of transmitting and receiving over any of the data wavelengths, facing the scalability issues. Two different slot reuse schemes are assumed: the source and the destination stripping schemes. For both schemes, performance measures evaluation is provided via an analytic model. The analytical results are validated by a discrete event simulation model that uses Poisson traffic sources. Simulation results show that the proposed protocol manages efficient bandwidth utilization, especially under high load. Also, comparative simulation results prove that our protocol achieves significant performance improvement as compared with other WDMA protocols which restrict transmission over a dedicated data wavelength. Finally, performance measures evaluation is explored for diverse numbers of buffer size, access nodes and data wavelengths.

  16. Availability and accessibility of evidence-based information resources provided by medical libraries in Australia.

    Science.gov (United States)

    Ritchie, A; Sowter, B

    2000-01-01

    This article reports on the results of an exploratory survey of the availability and accessibility of evidence-based information resources provided by medical libraries in Australia. Although barriers impede access to evidence-based information for hospital clinicians, the survey revealed that Medline and Cinahl are available in over 90% of facilities. In most cases they are widely accessible via internal networks and the Internet. The Cochrane Library is available in 69% of cases. The Internet is widely accessible and most libraries provide access to some full-text, electronic journals. Strategies for overcoming restrictions and integrating information resources with clinical workflow are being pursued. State, regional and national public and private consortia are developing agreements utilising on-line technology. These could produce cost savings and more equitable access to a greater range of evidence-based resources.

  17. STAR-TYPE LOCAL AREA NETWORK ACCESS CONTROL

    Institute of Scientific and Technical Information of China (English)

    逯昭义; 齐藤忠夫

    1990-01-01

    The multiple access fashion is a new resolution for the star-type local area network (LAN) access control and star-type optical fibre LAN. Arguments about this network are discussed, and the results are introduced.

  18. JNC's experience of complementary accesses provided by the additional protocol

    International Nuclear Information System (INIS)

    Miura, Yasushi

    2001-01-01

    JNC (Japan Nuclear Cycle Development Institute) examined problems on implementation of the Additional Protocol to Japan/IAEA Safeguards Agreement with the Government of Japan and International Atomic Energy Agency through trials performed at Oarai Engineering Center before it entered into force. On December 16th 1999, the Additional Protocol entered into force, and in last January JNC provided the first JNC site information to STA. Then our Government provided it of all Japan to IAEA in last June. Also in this January, we sent the additional information changed from old one to MEXT (Ministry of Education, Culture, Sports, Science and Technology). The first Complementary Access of not only JNC but also Japan was implemented on JNC Ningyo-Toge Environmental Engineering Center on the end of last November. Since then, we have had over 10 times experience of Complementary Accesses for about one year especially on Tokai works and Ningyo-Toge. JNC's experience of Complementary Accesses will be introduced. (author)

  19. Spectrum access and management for cognitive radio networks

    CERN Document Server

    2017-01-01

    This book presents cutting-edge research contributions that address various aspects of network design, optimization, implementation, and application of cognitive radio technologies. It demonstrates how to make better utilization of the available spectrum, cognitive radios and spectrum access to achieve effective spectrum sharing between licensed and unlicensed users. The book provides academics and researchers essential information on current developments and future trends in cognitive radios for possible integration with the upcoming 5G networks. In addition, it includes a brief introduction to cognitive radio networks for newcomers to the field.

  20. Metadata and Providing Access to e-Books

    Science.gov (United States)

    Vasileiou, Magdalini; Rowley, Jennifer; Hartley, Richard

    2013-01-01

    In the very near future, students are likely to expect their universities to provide seamless access to e-books through online library catalogues and virtual learning environments. A paradigm change in terms of the format of books, and especially textbooks, which could have far-reaching impact, is on the horizon. Based on interviews with a number…

  1. Providing Access to Library Automation Systems for Students with Disabilities.

    Science.gov (United States)

    California Community Colleges, Sacramento. High-Tech Center for the Disabled.

    This document provides information on the integration of assistive computer technologies and library automation systems at California Community Colleges in order to ensure access for students with disabilities. Topics covered include planning, upgrading, purchasing, implementing and using these technologies with library systems. As information…

  2. Rural providers' access to online resources: a randomized controlled trial

    Science.gov (United States)

    Hall, Laura J.; McElfresh, Karen R.; Warner, Teddy D.; Stromberg, Tiffany L.; Trost, Jaren; Jelinek, Devin A.

    2016-01-01

    Objective The research determined the usage and satisfaction levels with one of two point-of-care (PoC) resources among health care providers in a rural state. Methods In this randomized controlled trial, twenty-eight health care providers in rural areas were stratified by occupation and region, then randomized into either the DynaMed or the AccessMedicine study arm. Study participants were physicians, physician assistants, and nurses. A pre- and post-study survey measured participants' attitudes toward different information resources and their information-seeking activities. Medical student investigators provided training and technical support for participants. Data analyses consisted of analysis of variance (ANOVA), paired t tests, and Cohen's d statistic to compare pre- and post-study effects sizes. Results Participants in both the DynaMed and the AccessMedicine arms of the study reported increased satisfaction with their respective PoC resource, as expected. Participants in both arms also reported that they saved time in finding needed information. At baseline, both arms reported too little information available, which increased to “about right amounts of information” at the completion of the study. DynaMed users reported a Cohen's d increase of +1.50 compared to AccessMedicine users' reported use of 0.82. DynaMed users reported d2 satisfaction increases of 9.48 versus AccessMedicine satisfaction increases of 0.59 using a Cohen's d. Conclusion Participants in the DynaMed arm of the study used this clinically oriented PoC more heavily than the users of the textbook-based AccessMedicine. In terms of user satisfaction, DynaMed users reported higher levels of satisfaction than the users of AccessMedicine. PMID:26807050

  3. Wi-Fi Networks Security and Accessing Control

    OpenAIRE

    Tarek S. Sobh

    2013-01-01

    As wireless networks access gains popularity in corporate, private and personal networks, the nature of wireless networks opens up new possibilities for network attacks. This paper negotiating Wi-Fi security against scanning of rogue Wi-Fi networks and other related activities and considers the monitoring of Wi-Fi traffic effects. The unauthorized access point (AP) problem has raised more attention and resulted in obtaining wireless access without subscriber permission.This work assumes Wi-Fi...

  4. Sci-Hub provides access to nearly all scholarly literature.

    Science.gov (United States)

    Himmelstein, Daniel S; Romero, Ariel Rodriguez; Levernier, Jacob G; Munro, Thomas Anthony; McLaughlin, Stephen Reid; Greshake Tzovaras, Bastian; Greene, Casey S

    2018-03-01

    The website Sci-Hub enables users to download PDF versions of scholarly articles, including many articles that are paywalled at their journal's site. Sci-Hub has grown rapidly since its creation in 2011, but the extent of its coverage has been unclear. Here we report that, as of March 2017, Sci-Hub's database contains 68.9% of the 81.6 million scholarly articles registered with Crossref and 85.1% of articles published in toll access journals. We find that coverage varies by discipline and publisher, and that Sci-Hub preferentially covers popular, paywalled content. For toll access articles, we find that Sci-Hub provides greater coverage than the University of Pennsylvania, a major research university in the United States. Green open access to toll access articles via licit services, on the other hand, remains quite limited. Our interactive browser at https://greenelab.github.io/scihub allows users to explore these findings in more detail. For the first time, nearly all scholarly literature is available gratis to anyone with an Internet connection, suggesting the toll access business model may become unsustainable. © 2018, Himmelstein et al.

  5. Knowledge Access in Rural Inter-connected Areas Network ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Knowledge Access in Rural Inter-connected Areas Network (KariaNet) - Phase II ... the existing network to include two thematic networks on food security and rural ... Woman conquering male business in Yemen : Waleya's micro-enterprise.

  6. Optical solutions for unbundled access network

    Science.gov (United States)

    Bacîş Vasile, Irina Bristena

    2015-02-01

    The unbundling technique requires finding solutions to guarantee the economic and technical performances imposed by the nature of the services that can be offered. One of the possible solutions is the optic one; choosing this solution is justified for the following reasons: it optimizes the use of the access network, which is the most expensive part of a network (about 50% of the total investment in telecommunications networks) while also being the least used (telephone traffic on the lines has a low cost); it increases the distance between the master station/central and the terminal of the subscriber; the development of the services offered to the subscribers is conditioned by the subscriber network. For broadband services there is a need for support for the introduction of high-speed transport. A proper identification of the factors that must be satisfied and a comprehensive financial evaluation of all resources involved, both the resources that are in the process of being bought as well as extensions are the main conditions that would lead to a correct choice. As there is no single optimal technology for all development scenarios, which can take into account all access systems, a successful implementation is always done by individual/particularized scenarios. The method used today for the selection of an optimal solution is based on statistics and analysis of the various, already implemented, solutions, and on the experience that was already gained; the main evaluation criterion and the most unbiased one is the ratio between the cost of the investment and the quality of service, while serving an as large as possible number of customers.

  7. Random access procedures and radio access network (RAN) overload control in standard and advanced long-term evolution (LTE and LTE-A) networks

    DEFF Research Database (Denmark)

    Kiilerich Pratas, Nuno; Thomsen, Henning; Popovski, Petar

    2015-01-01

    In this chapter, we describe and discuss the current LTE random access procedure and the Radio Access Network Load Control solution within LTE/LTE-A. We provide an overview of the several considered load control solutions and give a detailed description of the standardized Extended Access Class B...

  8. A Fuzzy Preprocessing Module for Optimizing the Access Network Selection in Wireless Networks

    Directory of Open Access Journals (Sweden)

    Faisal Kaleem

    2013-01-01

    Full Text Available A heterogeneous wireless network is characterized by the presence of different wireless access technologies that coexist in an overlay fashion. These wireless access technologies usually differ in terms of their operating parameters. On the other hand, Mobile Stations (MSs in a heterogeneous wireless network are equipped with multiple interfaces to access different types of services from these wireless access technologies. The ultimate goal of these heterogeneous wireless networks is to provide global connectivity with efficient ubiquitous computing to these MSs based on the Always Best Connected (ABC principle. This is where the need for intelligent and efficient Vertical Handoffs (VHOs between wireless technologies in a heterogeneous environment becomes apparent. This paper presents the design and implementation of a fuzzy multicriteria based Vertical Handoff Necessity Estimation (VHONE scheme that determines the proper time for VHO, while considering the continuity and quality of the currently utilized service, and the end-users' satisfaction.

  9. Computer network access to scientific information systems for minority universities

    Science.gov (United States)

    Thomas, Valerie L.; Wakim, Nagi T.

    1993-08-01

    The evolution of computer networking technology has lead to the establishment of a massive networking infrastructure which interconnects various types of computing resources at many government, academic, and corporate institutions. A large segment of this infrastructure has been developed to facilitate information exchange and resource sharing within the scientific community. The National Aeronautics and Space Administration (NASA) supports both the development and the application of computer networks which provide its community with access to many valuable multi-disciplinary scientific information systems and on-line databases. Recognizing the need to extend the benefits of this advanced networking technology to the under-represented community, the National Space Science Data Center (NSSDC) in the Space Data and Computing Division at the Goddard Space Flight Center has developed the Minority University-Space Interdisciplinary Network (MU-SPIN) Program: a major networking and education initiative for Historically Black Colleges and Universities (HBCUs) and Minority Universities (MUs). In this paper, we will briefly explain the various components of the MU-SPIN Program while highlighting how, by providing access to scientific information systems and on-line data, it promotes a higher level of collaboration among faculty and students and NASA scientists.

  10. Resource Allocation for Cloud Radio Access Networks

    KAUST Repository

    Dhifallah, Oussama

    2016-04-01

    Cloud-radio access network (CRAN) is expected to be the core network architecture for next generation mobile radio system. In CRANs, joint signal processing is performed at multiple cloud computing centers (clouds) that are connected to several base stations (BSs) via high capacity backhaul links. As a result, large-scale interference management and network power consumption reduction can be effectively achieved. Unlike recent works on CRANs which consider a single cloud processing and treat inter-cloud interference as background noise, the first part of this thesis focuses on the more practical scenario of the downlink of a multi-cloud radio access network where BSs are connected to each cloud through wireline backhaul links. Assume that each cloud serves a set of pre-known single-antenna mobile users (MUs). This part focuses on minimizing the network total power consumption subject to practical constraints. The problems are solved using sophisticated techniques from optimization theory (e.g. Dual Decomposition-based algorithm and the alternating direction method of multipliers (ADMM)-based algorithm). One highlight of this part is that the proposed solutions can be implemented in a distributed fashion by allowing a reasonable information exchange between the coupled clouds. Additionally, feasible solutions of the considered optimization problems can be estimated locally at each iteration. Simulation results show that the proposed distributed algorithms converge to the centralized algorithms in a reasonable number of iterations. To further account of the backhaul congestion due to densification in CRANs, the second part of this thesis considers the downlink of a cache-enabled CRAN where each BS is equipped with a local-cache with limited size used to store the popular files without the need for backhauling. Further, each cache-enabled BS is connected to the cloud via limited capacity backhaul link and can serve a set of pre-known single antenna MUs. This part

  11. A Systematic Scheme for Multiple Access in Ethernet Passive Optical Access Networks

    Science.gov (United States)

    Ma, Maode; Zhu, Yongqing; Hiang Cheng, Tee

    2005-11-01

    While backbone networks have experienced substantial changes in the last decade, access networks have not changed much. Recently, passive optical networks (PONs) seem to be ready for commercial deployment as access networks, due to the maturity of a number of enabling technologies. Among the PON technologies, Ethernet PON (EPON) standardized by the IEEE 802.3ah Ethernet in the First Mile (EFM) Task Force is the most attractive one because of its high speed, low cost, familiarity, interoperability, and low overhead. In this paper, we consider the issue of upstream channel sharing in the EPONs. We propose a novel multiple-access control scheme to provide bandwidth-guaranteed service for high-demand customers, while providing best effort service to low-demand customers according to the service level agreement (SLA). The analytical and simulation results prove that the proposed scheme performs best in what it is designed to do compared to another well-known scheme that has not considered providing differentiated services. With business customers preferring premium services with guaranteed bandwidth and residential users preferring low-cost best effort services, our scheme could benefit both groups of subscribers, as well as the operators.

  12. What Type of Knowledge Provides Valid Housing Standards Addressing Accessibility?

    DEFF Research Database (Denmark)

    Helle, Tina; Brandt, Åse; Iwarsson, Susanne

    evaluations of task-surface heights in elderly people’s homes. Applied Ergonomics, 31, 109-119. Kohlbacher, F. (2006). The use of qualitative content analysis in case study research. Forum: Qualitative social research sozialforschung (FQS), Open Journal Systems, vol 7, No1. Kozey, J.W. & Das, B. (2004...... accessibility aspects such as either reach, seat height or space requirements • Targeted primarily industrial workstation design and only wheelchair/scooter users • Addressed positions (standing/seated) and sex difference with respect to reach • Was generated in lab-like environments, using methods...... of the validity of housing standards. Therefore, it is reasonable to question what type of knowledge that provides the most valid standards addressing accessibility and explore the consequences of using an alternative approach. The idea was thus to examine the validity of a set of housing standards using a so...

  13. Radio Access Sharing Strategies for Multiple Operators in Cellular Networks

    DEFF Research Database (Denmark)

    Popovska Avramova, Andrijana; Iversen, Villy Bæk

    2015-01-01

    deployments (required for coverage enhancement), increased base station utilization, and reduced overall power consumption. Today, network sharing in the radio access part is passive and limited to cell sites. With the introduction of Cloud Radio Access Network and Software Defined Networking adoption...... to the radio access network, the possibility for sharing baseband processing and radio spectrum becomes an important aspect of network sharing. This paper investigates strategies for active sharing of radio access among multiple operators, and analyses the individual benefits depending on the sharing degree...

  14. Virtualized Network Function Orchestration System and Experimental Network Based QR Recognition for a 5G Mobile Access Network

    Directory of Open Access Journals (Sweden)

    Misun Ahn

    2017-12-01

    Full Text Available This paper proposes a virtualized network function orchestration system based on Network Function Virtualization (NFV, one of the main technologies in 5G mobile networks. This system should provide connectivity between network devices and be able to create flexible network function and distribution. This system focuses more on access networks. By experimenting with various scenarios of user service established and activated in a network, we examine whether rapid adoption of new service is possible and whether network resources can be managed efficiently. The proposed method is based on Bluetooth transfer technology and mesh networking to provide automatic connections between network machines and on a Docker flat form, which is a container virtualization technology for setting and managing key functions. Additionally, the system includes a clustering and recovery measure regarding network function based on the Docker platform. We will briefly introduce the QR code perceived service as a user service to examine the proposal and based on this given service, we evaluate the function of the proposal and present analysis. Through the proposed approach, container relocation has been implemented according to a network device’s CPU usage and we confirm successful service through function evaluation on a real test bed. We estimate QR code recognition speed as the amount of network equipment is gradually increased, improving user service and confirm that the speed of recognition is increased as the assigned number of network devices is increased by the user service.

  15. Next Generation Access Network Deployment in Croatia: Optical Access Networks and Current IoT/5G Status

    Science.gov (United States)

    Breskovic, Damir; Sikirica, Mladen; Begusic, Dinko

    2018-05-01

    This paper gives an overview and background of optical access network deployment in Croatia. Optical access network development in Croatia has been put into a global as well as in the European Union context. All the challenges and the driving factors for optical access networks deployment are considered. Optical access network architectures that have been deployed by most of the investors in Croatian telecommunication market are presented, as well as the architectures that are in early phase of deployment. Finally, an overview on current status of mobile networks of the fifth generation and Internet of Things is given.

  16. The entire network topology display system of terminal communication access network

    OpenAIRE

    An Yi

    2016-01-01

    Now order terminal communication access network is network technology in Shanxi Province is diversiform, device type complex, lack of unified technical standard, the terminal communication access network management system of construction constitutes a great obstacle. Need to build a “unified communication interface and communication standard, unified communications network management” of the terminal communication access network cut in the integrated network management system, for the termina...

  17. MPTCP Tunnel: An Architecture for Aggregating Bandwidth of Heterogeneous Access Networks

    Directory of Open Access Journals (Sweden)

    Xiaolan Liu

    2018-01-01

    Full Text Available Fixed and cellular networks are two typical access networks provided by operators. Fixed access network is widely employed; nevertheless, its bandwidth is sometimes not sufficient enough to meet user bandwidth requirements. Meanwhile, cellular access network owns unique advantages of wider coverage, faster increasing link speed, more flexible deployment, and so forth. Therefore, it is attractive for operators to mitigate the bandwidth shortage by bundling these two. Actually, there have been existing schemes proposed to aggregate the bandwidth of two access networks, whereas they all have their own problems, like packet reordering or extra latency overhead. To address this problem, we design new architecture, MPTCP Tunnel, to aggregate the bandwidth of multiple heterogeneous access networks from the perspective of operators. MPTCP Tunnel uses MPTCP, which solves the reordering problem essentially, to bundle multiple access networks. Besides, MPTCP Tunnel sets up only one MPTCP connection at play which adapts itself to multiple traffic types and TCP flows. Furthermore, MPTCP Tunnel forwards intact IP packets through access networks, maintaining the end-to-end TCP semantics. Experimental results manifest that MPTCP Tunnel can efficiently aggregate the bandwidth of multiple access networks and is more adaptable to the increasing heterogeneity of access networks than existing mechanisms.

  18. Scalable Lunar Surface Networks and Adaptive Orbit Access

    Science.gov (United States)

    Wang, Xudong

    2015-01-01

    Teranovi Technologies, Inc., has developed innovative network architecture, protocols, and algorithms for both lunar surface and orbit access networks. A key component of the overall architecture is a medium access control (MAC) protocol that includes a novel mechanism of overlaying time division multiple access (TDMA) and carrier sense multiple access with collision avoidance (CSMA/CA), ensuring scalable throughput and quality of service. The new MAC protocol is compatible with legacy Institute of Electrical and Electronics Engineers (IEEE) 802.11 networks. Advanced features include efficiency power management, adaptive channel width adjustment, and error control capability. A hybrid routing protocol combines the advantages of ad hoc on-demand distance vector (AODV) routing and disruption/delay-tolerant network (DTN) routing. Performance is significantly better than AODV or DTN and will be particularly effective for wireless networks with intermittent links, such as lunar and planetary surface networks and orbit access networks.

  19. The effect of narrow provider networks on health care use.

    Science.gov (United States)

    Atwood, Alicia; Lo Sasso, Anthony T

    2016-12-01

    Network design is an often overlooked aspect of health insurance contracts. Recent policy factors have resulted in narrower provider networks. We provide plausibly causal evidence on the effect of narrow network plans offered by a large national health insurance carrier in a major metropolitan market. Our econometric design exploits the fact that some firms offer a narrow network plan to their employees and some do not. Our results show that narrow network health plans lead to reductions in health care utilization and spending. We find evidence that narrow networks save money by selecting lower cost providers into the network. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. LTER network data access policy revision: report and recommendations.

    Science.gov (United States)

    James Brunt; Peter McCartney; Stuart Gage; Don. Henshaw

    2004-01-01

    This document is a report on work carried out to update the LTER Network Data Access Policy. The current LTER Network Data Access Policy, approved by the coordinating committee in 1997, has been in use since 1990. An analysis of the current policies related to the release, access, and use of LTER data has been undertaken by a sub-committee of the LTER Network...

  1. On Planning of FTTH Access Networks with and without Redundancy

    DEFF Research Database (Denmark)

    Riaz, M. Tahir; Haraldsson, Gustav; Gutierrez Lopez, Jose Manuel

    2010-01-01

    This paper presents a planning analysis of FTTH access network with and without redundancy. Traditionally, access networks are planned only without redundancy, which is mainly due to lowering the cost of deployment. As fiber optics provide a huge amount of capacity, more and more services are being...... offered on a single fiber connection. As a single point of failure in fiber connection can cause multiple service deprivation therefore redundancy is very crucial. In this work, an automated planning model was used to test different scenarios of implementation. A cost estimation is presented in terms...... of digging and amount of fiber used. Three topologies, including the traditional one “tree topology”, were test with combination of various passive optical technologies....

  2. Distributed cloud association in downlink multicloud radio access networks

    KAUST Repository

    Dahrouj, Hayssam; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2015-01-01

    This paper considers a multicloud radio access network (M-CRAN), wherein each cloud serves a cluster of base-stations (BS's) which are connected to the clouds through high capacity digital links. The network comprises several remote users, where

  3. Knowledge Access in Rural Inter-connected Areas Network ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Knowledge Access in Rural Inter-connected Areas Network (KariaNet) - Phase II ... poor by sharing innovations, best practices and indigenous knowledge using ... A third thematic network - on knowledge management strategies - will play an ...

  4. Accessing the nanostructural analysis network organisation (NANO)

    International Nuclear Information System (INIS)

    Hicks, R.; Ringer, S.

    2003-01-01

    Full text: As a Major National Research Facility (MNRF), NANO unites five Australian microscopy and microanalysis centres to form the peak Australian facility for nanometric analysis of the structure and chemistry of materials. NANO is headquartered at the Australian Key Centre for Microscopy and Microanalysis at the University of Sydney and involves the Centres for Microscopy and Microanalysis at the Universities of Queensland and Western Australia, the Electron Microscope Unit at the University of New South Wales and the Microanalytical Research Centre at the University of Melbourne. Together these major centres maintain a wide range of complementary instrumentation for the characterisation of nanostructure. NANO links them into a co-ordinated national facility with unified charges and booking systems. The facility will provide open access to a wide range of present and future partners involving local and international linkages. For this reason, NANO is designed to allow the incorporation of other groups as additional nodes. All Australian researchers are eligible to apply for support to use NANO through the Travel and Access Program (NANO-TAP), which will support basic travel and accommodation costs as well as instrument time. Access to the national grid may involve on-site presence at a particular node or remote telemicroscopy. Both passive (observation) and active (operation) modes of telemicroscopy are available. This presentation will address the NANO-TAP application procedure, the use of remote telemicroscopy and the formation of additional nodes. Copyright (2003) Australian Microbeam Analysis Society

  5. Distributed cloud association in downlink multicloud radio access networks

    KAUST Repository

    Dahrouj, Hayssam

    2015-03-01

    This paper considers a multicloud radio access network (M-CRAN), wherein each cloud serves a cluster of base-stations (BS\\'s) which are connected to the clouds through high capacity digital links. The network comprises several remote users, where each user can be connected to one (and only one) cloud. This paper studies the user-to-cloud-assignment problem by maximizing a network-wide utility subject to practical cloud connectivity constraints. The paper solves the problem by using an auction-based iterative algorithm, which can be implemented in a distributed fashion through a reasonable exchange of information between the clouds. The paper further proposes a centralized heuristic algorithm, with low computational complexity. Simulations results show that the proposed algorithms provide appreciable performance improvements as compared to the conventional cloud-less assignment solutions. © 2015 IEEE.

  6. Network Performance and Quality of Experience of Remote Access Laboratories

    Directory of Open Access Journals (Sweden)

    Alexander A. Kist

    2012-11-01

    Full Text Available Remote Access Laboratories (RAL have become important learning and teaching tools. This paper presents a performance study that targets a specific remote access architecture implemented within a universities operational environment. This particular RAL system provides globally authenticated and arbitrated remote access to virtualized computers as well as computer controlled hardware experiments. This paper presents system performance results that have been obtained utilizing both a set of automated and human subject tests. Principle objectives of the study were: To gain a better understanding of the nature of network traffic caused by experimental activity usage; to obtain an indication of user expectations of activity performance; and to develop a measure to predict Quality of Experience, based on easily measurable Quality of Service parameters. The study emulates network layer variation of access-bandwidth and round-trip-time of typical usage scenarios and contrasts against user perception results that allow classifying expected user performance. It demonstrates that failure rate is excellent measure of usability, and that round-trip-time predominantly affects user experience. Thin-client and remote desktop architectures are popular to separate the location of users and the actual data processing and use similar structures, hence results of this study to be applied in these application areas as well.

  7. Research of user access control for networked manufacturing system

    Institute of Scientific and Technical Information of China (English)

    ZHENG Xiao-lin; LEI Yu; CHEN De-ren

    2006-01-01

    An integrated user access control method was proposed to address the issues of security and management in networked manufacturing systems (NMS).Based on the analysis of the security issues in networked manufacturing system,an integrated user access control method composed of role-based access control (RBAC),task-based access control (TBAC),relationship-driven access control (RDAC)and coalition-based access control (CBAC) was proposed,including the hierarchical user relationship model,the reference model and the process model.The elements and their relationships were defined,and the expressions of constraints authorization were given.The extensible access control markup language (XACML) was used to implement this method.This method was used in the networked manufacturing system in the Shaoxing spinning region of China.The results show that the integrated user access control method can reduce the costs of system security maintenance and management.

  8. Models for QoS-Aware Capacity Management in Cable Access Networks

    NARCIS (Netherlands)

    Attema, T.; van den Berg, Hans Leo; Kempker, P.C.; Worm, D.; van der Vliet-Hameeteman, C.

    In this article, mathematical models are presented that “map‿ measured or predicted network utilisations to user throughputs for given network configurations (segment capacity, subscription speeds etc.). They provide valuable insights into the user experience in cable access networks. The models,

  9. A Unified Access Model for Interconnecting Heterogeneous Wireless Networks

    Science.gov (United States)

    2015-05-01

    validation of the proposed network design for unified network access, and it lays the foundation for implementing a Software - Defined Networking ( SDN ...York (NY): Springer; 2014. Chapter 2, Software - defined networking ; p. 19–32. 5. Sharma S, Staessens D, Colle D, Pickavet M, Demeester P. A...demonstration of fast failure recovery in software defined networking . In: Korakis T, Zink M, Ott, M, editors. Testbeds and research infrastructure

  10. Accessing Wireless Sensor Networks Via Dynamically Reconfigurable Interaction Models

    Directory of Open Access Journals (Sweden)

    Maria Cecília Gomes

    2012-12-01

    Full Text Available The Wireless Sensor Networks (WSNs technology is already perceived as fundamental for science across many domains, since it provides a low cost solution for environment monitoring. WSNs representation via the service concept and its inclusion in Web environments, e.g. through Web services, supports particularly their open/standard access and integration. Although such Web enabled WSNs simplify data access, network parameterization and aggregation, the existing interaction models and run-time adaptation mechanisms available to clients are still scarce. Nevertheless, applications increasingly demand richer and more flexible accesses besides the traditional client/server. For instance, applications may require a streaming model in order to avoid sequential data requests, or the asynchronous notification of subscribed data through the publish/subscriber. Moreover, the possibility to automatically switch between such models at runtime allows applications to define flexible context-based data acquisition. To this extent, this paper discusses the relevance of the session and pattern abstractions on the design of a middleware prototype providing richer and dynamically reconfigurable interaction models to Web enabled WSNs.

  11. Cell Deployment Optimization for Cloud Radio Access Networks using Teletraffic Theory

    DEFF Research Database (Denmark)

    Popovska Avramova, Andrijana; Christiansen, Henrik Lehrmann; Iversen, Villy Bæk

    2015-01-01

    Cloud Radio Access Network (C-RAN) is a new mobile radio access network design based on centralized and pooled processing. It offers potential cost savings by utilizing the so-called tidal effect due to user mobility in cellular networks. This paper provides a quantitative analysis...... to dynamically re-assign cells to a pool of baseband units. The re-assignment is based on the cell load and traffic characteristics such that effective utilization of the baseband resources is assured....

  12. Effects of network node consolidation in optical access and aggregation networks on costs and power consumption

    Science.gov (United States)

    Lange, Christoph; Hülsermann, Ralf; Kosiankowski, Dirk; Geilhardt, Frank; Gladisch, Andreas

    2010-01-01

    The increasing demand for higher bit rates in access networks requires fiber deployment closer to the subscriber resulting in fiber-to-the-home (FTTH) access networks. Besides higher access bit rates optical access network infrastructure and related technologies enable the network operator to establish larger service areas resulting in a simplified network structure with a lower number of network nodes. By changing the network structure network operators want to benefit from a changed network cost structure by decreasing in short and mid term the upfront investments for network equipment due to concentration effects as well as by reducing the energy costs due to a higher energy efficiency of large network sites housing a high amount of network equipment. In long term also savings in operational expenditures (OpEx) due to the closing of central office (CO) sites are expected. In this paper different architectures for optical access networks basing on state-of-the-art technology are analyzed with respect to network installation costs and power consumption in the context of access node consolidation. Network planning and dimensioning results are calculated for a realistic network scenario of Germany. All node consolidation scenarios are compared against a gigabit capable passive optical network (GPON) based FTTH access network operated from the conventional CO sites. The results show that a moderate reduction of the number of access nodes may be beneficial since in that case the capital expenditures (CapEx) do not rise extraordinarily and savings in OpEx related to the access nodes are expected. The total power consumption does not change significantly with decreasing number of access nodes but clustering effects enable a more energyefficient network operation and optimized power purchase order quantities leading to benefits in energy costs.

  13. Symmetric reconfigurable capacity assignment in a bidirectional DWDM access network.

    Science.gov (United States)

    Ortega, Beatriz; Mora, José; Puerto, Gustavo; Capmany, José

    2007-12-10

    This paper presents a novel architecture for DWDM bidirectional access networks providing symmetric dynamic capacity allocation for both downlink and uplink signals. A foldback arrayed waveguide grating incorporating an optical switch enables the experimental demonstration of flexible assignment of multiservice capacity. Different analog and digital services, such as CATV, 10 GHz-tone, 155Mb/s PRBS and UMTS signals have been transmitted in order to successfully test the system performance under different scenarios of total capacity distribution from the Central Station to different Base Stations with two reconfigurable extra channels for each down and upstream direction.

  14. Formal Specification and Validation of Secure Connection Establishment in a Generic Access Network Scenario

    DEFF Research Database (Denmark)

    Fleischer, Paul; Kristensen, Lars Michael

    2008-01-01

    The Generic Access Network (GAN) architecture is defined by the 3rd Generation Partnership Project (3GPP), and allows telephone services, such as SMS and voice-calls, to be accessed via generic IP networks. The main usage of this is to allow mobile phones to use WiFi in addition to the usual GSM...... network. The GAN specification relies on the Internet Protocol Security layer (IPSec) and the Internet Key Exchange protocol (IKEv2) to provide encryption across IP networks, and thus avoid compromising the security of the telephone networks. The detailed usage of these two Internet protocols (IPSec...

  15. Resource allocation in heterogeneous cloud radio access networks: advances and challenges

    KAUST Repository

    Dahrouj, Hayssam; Douik, Ahmed S.; Dhifallah, Oussama Najeeb; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2015-01-01

    , becomes a necessity. By connecting all the base stations from different tiers to a central processor (referred to as the cloud) through wire/wireline backhaul links, the heterogeneous cloud radio access network, H-CRAN, provides an open, simple

  16. Fiber Access Networks: Reliability Analysis and Swedish Broadband Market

    Science.gov (United States)

    Wosinska, Lena; Chen, Jiajia; Larsen, Claus Popp

    Fiber access network architectures such as active optical networks (AONs) and passive optical networks (PONs) have been developed to support the growing bandwidth demand. Whereas particularly Swedish operators prefer AON, this may not be the case for operators in other countries. The choice depends on a combination of technical requirements, practical constraints, business models, and cost. Due to the increasing importance of reliable access to the network services, connection availability is becoming one of the most crucial issues for access networks, which should be reflected in the network owner's architecture decision. In many cases protection against failures is realized by adding backup resources. However, there is a trade off between the cost of protection and the level of service reliability since improving reliability performance by duplication of network resources (and capital expenditures CAPEX) may be too expensive. In this paper we present the evolution of fiber access networks and compare reliability performance in relation to investment and management cost for some representative cases. We consider both standard and novel architectures for deployment in both sparsely and densely populated areas. While some recent works focused on PON protection schemes with reduced CAPEX the current and future effort should be put on minimizing the operational expenditures (OPEX) during the access network lifetime.

  17. Open Orchestration Cloud Radio Access Network (OOCRAN) Testbed

    OpenAIRE

    Floriach-Pigem, Marti; Xercavins-Torregrosa, Guillem; Marojevic, Vuk; Gelonch-Bosch, Antoni

    2017-01-01

    The Cloud radio access network (C-RAN) offers a revolutionary approach to cellular network deployment, management and evolution. Advances in software-defined radio (SDR) and networking technology, moreover, enable delivering software-defined everything through the Cloud. Resources will be pooled and dynamically allocated leveraging abstraction, virtualization, and consolidation techniques; processes will be automated using common application programming interfaces; and network functions and s...

  18. Software Defined Networking for Next Generation Converged Metro-Access Networks

    Science.gov (United States)

    Ruffini, M.; Slyne, F.; Bluemm, C.; Kitsuwan, N.; McGettrick, S.

    2015-12-01

    While the concept of Software Defined Networking (SDN) has seen a rapid deployment within the data center community, its adoption in telecommunications network has progressed slowly, although the concept has been swiftly adopted by all major telecoms vendors. This paper presents a control plane architecture for SDN-driven converged metro-access networks, developed through the DISCUS European FP7 project. The SDN-based controller architecture was developed in a testbed implementation targeting two main scenarios: fast feeder fiber protection over dual-homed Passive Optical Networks (PONs) and dynamic service provisioning over a multi-wavelength PON. Implementation details and results of the experiment carried out over the second scenario are reported in the paper, showing the potential of SDN in providing assured on-demand services to end-users.

  19. Easy Access: Auditing the System Network

    Science.gov (United States)

    Wiech, Dean

    2013-01-01

    In today's electronic learning environment, access to appropriate systems and data is of the utmost importance to students, faculty, and staff. Without proper access to the school's internal systems, teachers could be prevented from logging on to an online learning system and students might be unable to submit course work to an online…

  20. Rural women and violence situation: access and accessibility limits to the healthcare network.

    Science.gov (United States)

    Costa, Marta Cocco da; Silva, Ethel Bastos da; Soares, Joannie Dos Santos Fachinelli; Borth, Luana Cristina; Honnef, Fernanda

    2017-07-13

    To analyze the access and accessibility to the healthcare network of women dwelling in rural contexts undergoing violence situation, as seen from the professionals' speeches. A qualitative, exploratory, descriptive study with professionals from the healthcare network services about coping with violence in four municipalities in the northern region of Rio Grande do Sul. The information derived from interviews, which have been analyzed by thematic modality. (Lack of) information of women, distance, restricted access to transportation, dependence on the partner and (lack of) attention by professionals to welcome women undergoing violence situation and (non)-articulation of the network are factors that limit the access and, as a consequence, they result in the lack of confrontation of this problem. To bring closer the services which integrate the confrontation network of violence against women and to qualify professionals to welcome these situations are factors that can facilitate the access and adhesion of rural women to the services.

  1. The Design of Passive Optical Networking+Ethernet over Coaxial Cable Access Networking and Video-on-Demand Services Carrying

    Science.gov (United States)

    Ji, Wei

    2013-07-01

    Video on demand is a very attractive service used for entertainment, education, and other purposes. The design of passive optical networking+Ethernet over coaxial cable accessing and a home gateway system is proposed. The network integrates the passive optical networking and Ethernet over coaxial cable to provide high dedicated bandwidth for the metropolitan video-on-demand services. Using digital video broadcasting, IP television protocol, unicasting, and broadcasting mechanisms maximizes the system throughput. The home gateway finishes radio frequency signal receiving and provides three kinds of interfaces for high-definition video, voice, and data, which achieves triple-play and wire/wireless access synchronously.

  2. Measuring sustainable accessibility potential using the mobility infrastructure's network configuration

    NARCIS (Netherlands)

    Gil, J.; Read, S.

    2012-01-01

    This paper is an exploration into the analysis of public transport networks using space syntax approaches combined with concepts of sustainable accessibility. Present urban development policy aims to achieve sustainable mobility patterns, shifting mobility to soft transportation modes such as

  3. A New Hybrid Channel Access Scheme for Ad Hoc Networks

    National Research Council Canada - National Science Library

    Wang, Yu; Garcia-Luna-Aceves, J. J

    2002-01-01

    Many contention-based channel access schemes have been proposed for multi-hop ad hoc networks in the recent past, and they can be divided into two categories, sender-initiated and receiver-initiated...

  4. Algorithmic PON/P2P FTTH Access Network Design for CAPEX Minimization

    DEFF Research Database (Denmark)

    Papaefthimiou, Kostantinos; Tefera, Yonas; Mihylov, Dimitar

    2013-01-01

    one. It provides an obvious advantage for the end users in terms of high achievable data rates. On the other hand, the high initial deployment cost required exists as the heaviest impediment. The main goal of this paper is to study different approaches when designing a fiber access network. More......Due to the emergence of high bandwidth-requiring services, telecommunication operators (telcos) are called to upgrade their fixed access network. In order to keep up with the competition, they must consider different optical access network solutions with Fiber To The Home (FTTH) as the prevailing...

  5. Allocating resources between network nodes for providing a network node function

    NARCIS (Netherlands)

    Strijkers, R.J.; Meulenhoff, P.J.

    2014-01-01

    The invention provides a method wherein a first network node advertises available resources that a second network node may use to offload network node functions transparently to the first network node. Examples of the first network node are a client device (e.g. PC, notebook, tablet, smart phone), a

  6. A Method for Automated Planning of FTTH Access Network Infrastructures

    DEFF Research Database (Denmark)

    Riaz, Muhammad Tahir; Pedersen, Jens Myrup; Madsen, Ole Brun

    2005-01-01

    In this paper a method for automated planning of Fiber to the Home (FTTH) access networks is proposed. We introduced a systematic approach for planning access network infrastructure. The GIS data and a set of algorithms were employed to make the planning process more automatic. The method explains...... method. The method, however, does not fully automate the planning but make the planning process significantly fast. The results and discussion are presented and conclusion is given in the end....

  7. Security Issues in Networks with Internet Access

    National Research Council Canada - National Science Library

    Landwehr, Carl E; Goldschlag, David M

    1997-01-01

    .... The principles are illustrated by describing the security issues a hypothetical company faces as the networks that support its operations evolve from strictly private, through a mix of Internet...

  8. Wavelength-converted long-reach reconfigurable optical access network

    NARCIS (Netherlands)

    Tran, N.C.; Tangdiongga, E.; Koonen, A.M.J.

    2012-01-01

    Next generation optical access networks should not only increase the capacity but also be able to redistribute the capacity on the fly in order to manage more fluctuated traffic patterns. Wavelength reconfigurability is the instrument to enable such capability of network-wide bandwidth

  9. Network Information Management: The Key To Providing High WAN Availability.

    Science.gov (United States)

    Tysdal, Craig

    1996-01-01

    Discusses problems associated with increasing corporate network complexity as a result of the proliferation of client/server applications at remote locations, and suggests the key to providing high WAN (wide area network) availability is relational databases used in an integrated management approach. (LRW)

  10. Reliability Demands in FTTH Access Networks

    DEFF Research Database (Denmark)

    Pedersen, Jens Myrup; Knudsen, Thomas Phillip; Madsen, Ole Brun

    2004-01-01

    In this paper reliability and bandwidth demands of existing, new and expected classes of applications running over Fiber To The Home (FTTH) networks to private users and small enterprises are analyzed and discussed. Certain applications such as home security and telemedicine are likely to require...

  11. Reliability Demands in FTTH Access Networks

    DEFF Research Database (Denmark)

    Pedersen, Jens Myrup; Knudsen, Thomas Phillip; Madsen, Ole Brun

    2005-01-01

    In this paper reliability and bandwidth demands of existing, new and expected classes of applications running over Fiber To The Home (FTTH) networks to private users and small enterprises are analysed and discussed. Certain applications such as home security and telemedicine are likely to require...

  12. Allocating resources between network nodes for providing a network node function

    OpenAIRE

    Strijkers, R.J.; Meulenhoff, P.J.

    2014-01-01

    The invention provides a method wherein a first network node advertises available resources that a second network node may use to offload network node functions transparently to the first network node. Examples of the first network node are a client device (e.g. PC, notebook, tablet, smart phone), a server (e.g. application server, a proxy server, cloud location, router). Examples of the second network node are an application server, a cloud location or a router. The available resources may b...

  13. Joint Hybrid Backhaul and Access Links Design in Cloud-Radio Access Networks

    KAUST Repository

    Dhifallah, Oussama Najeeb; Dahrouj, Hayssam; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2015-01-01

    The cloud-radio access network (CRAN) is expected to be the core network architecture for next generation mobile radio systems. In this paper, we consider the downlink of a CRAN formed of one central processor (the cloud) and several base station

  14. Multiple access protocol for supporting multimedia services in wireless ATM networks

    DEFF Research Database (Denmark)

    Liu, Hong; Dittmann, Lars; Gliese, Ulrik Bo

    1999-01-01

    The furture broadband wireless asynchronous transfer mode (ATM) networks must provide seamless extension of multimedia services from the wireline ATM networks. This requires an effecient wireless access protocol to fulfill varying Quality-og-Service (QoS) requirements for multimedia applications....... In this paper, we propose a multiple access protocol using centralized and distributed channel access control techniques to provide QoS guarantees for multimedia services by taking advantage of the characteristics of different kinds of ATM traffics. Multimedia traffic, including constant bit rate (CBR...

  15. Simulation and measurement of optical access network with different types of optical-fiber amplifiers

    Science.gov (United States)

    Latal, Jan; Vogl, Jan; Koudelka, Petr; Vitasek, Jan; Siska, Petr; Liner, Andrej; Papes, Martin; Vasinek, Vladimir

    2012-01-01

    The optical access networks are nowadays swiftly developing in the telecommunications field. These networks can provide higher data transfer rates, and have great potential to the future in terms of transmission possibilities. Many local internet providers responded to these facts and began gradually installing optical access networks into their originally built networks, mostly based on wireless communication. This allowed enlargement of possibilities for end-users in terms of high data rates and also new services such as Triple play, IPTV (Internet Protocol television) etc. However, with this expansion and building-up is also related the potential of reach in case of these networks. Big cities, such as Prague, Brno, Ostrava or Olomouc cannot be simply covered, because of their sizes and also because of their internal regulations given by various organizations in each city. Standard logical and also physical reach of EPON (IEEE 802.3ah - Ethernet Passive Optical Network) optical access network is about 20 km. However, for networks based on Wavelength Division Multiplex the reach can be up to 80 km, if the optical-fiber amplifier is inserted into the network. This article deals with simulation of different types of amplifiers for WDM-PON (Wavelength Division Multiplexing-Passive Optical Network) network in software application Optiwave OptiSystem and than are the values from the application and from real measurement compared.

  16. Auctioning access to networks: evidence and expectations

    International Nuclear Information System (INIS)

    McDaniel, T.

    2003-01-01

    Under very strict assumptions the outcomes that make common auction designs theoretically attractive can be expected to emerge: goods will go to those who value them most and the allocation will maximize revenue for the auctioneer. In network industries such as electricity, gas, telecommunications, rail, and airlines where agents are of different sizes and incumbency these assumptions do not always apply for a number of reasons. For example, the auctioned product may be an intermediate good, bidders are not symmetric with respect to values and information, markets are mixed, and property rights are hard to define. We discuss why it is not straightforward to make theoretical predictions about expected outcomes for these industries and use the British gas industry to discuss the importance of competition and scarcity for auctions of network capacity. (Author)

  17. Design mobile satellite system architecture as an integral part of the cellular access digital network

    Science.gov (United States)

    Chien, E. S. K.; Marinho, J. A.; Russell, J. E., Sr.

    1988-01-01

    The Cellular Access Digital Network (CADN) is the access vehicle through which cellular technology is brought into the mainstream of the evolving integrated telecommunications network. Beyond the integrated end-to-end digital access and per call network services provisioning of the Integrated Services Digital Network (ISDN), the CADN engenders the added capability of mobility freedom via wireless access. One key element of the CADN network architecture is the standard user to network interface that is independent of RF transmission technology. Since the Mobile Satellite System (MSS) is envisioned to not only complement but also enhance the capabilities of the terrestrial cellular telecommunications network, compatibility and interoperability between terrestrial cellular and mobile satellite systems are vitally important to provide an integrated moving telecommunications network of the future. From a network standpoint, there exist very strong commonalities between the terrestrial cellular system and the mobile satellite system. Therefore, the MSS architecture should be designed as an integral part of the CADN. This paper describes the concept of the CADN, the functional architecture of the MSS, and the user-network interface signaling protocols.

  18. Security measures effect over performance in service provider network

    African Journals Online (AJOL)

    pc

    2018-03-05

    Mar 5, 2018 ... Abstract—network security is defined as a set of policies and actions taken by a ... These threats are linked with the following factors that are ... typically smaller than those in the service provider space. ... Service providers cannot manage to provide ... e the DB performance effect ... r the business needs [10].

  19. Optimizing Cooperative Cognitive Radio Networks with Opportunistic Access

    KAUST Repository

    Zafar, Ammar; Alouini, Mohamed-Slim; Chen, Yunfei; Radaydeh, Redha M.

    2012-01-01

    Optimal resource allocation for cooperative cognitive radio networks with opportunistic access to the licensed spectrum is studied. Resource allocation is based on minimizing the symbol error rate at the receiver. Both the cases of all-participate relaying and selective relaying are considered. The objective function is derived and the constraints are detailed for both scenarios. It is then shown that the objective functions and the constraints are nonlinear and nonconvex functions of the parameters of interest, that is, source and relay powers, symbol time, and sensing time. Therefore, it is difficult to obtain closed-form solutions for the optimal resource allocation. The optimization problem is then solved using numerical techniques. Numerical results show that the all-participate system provides better performance than its selection counterpart, at the cost of greater resources. © 2012 Ammar Zafar et al.

  20. Optimizing Cooperative Cognitive Radio Networks with Opportunistic Access

    KAUST Repository

    Zafar, Ammar

    2012-09-16

    Optimal resource allocation for cooperative cognitive radio networks with opportunistic access to the licensed spectrum is studied. Resource allocation is based on minimizing the symbol error rate at the receiver. Both the cases of all-participate relaying and selective relaying are considered. The objective function is derived and the constraints are detailed for both scenarios. It is then shown that the objective functions and the constraints are nonlinear and nonconvex functions of the parameters of interest, that is, source and relay powers, symbol time, and sensing time. Therefore, it is difficult to obtain closed-form solutions for the optimal resource allocation. The optimization problem is then solved using numerical techniques. Numerical results show that the all-participate system provides better performance than its selection counterpart, at the cost of greater resources. © 2012 Ammar Zafar et al.

  1. Performance analysis of quantum access network using code division multiple access model

    International Nuclear Information System (INIS)

    Hu Linxi; Yang Can; He Guangqiang

    2017-01-01

    A quantum access network has been implemented by frequency division multiple access and time division multiple access, while code division multiple access is limited for its difficulty to realize the orthogonality of the code. Recently, the chaotic phase shifters were proposed to guarantee the orthogonality by different chaotic signals and spread the spectral content of the quantum states. In this letter, we propose to implement the code division multiple access quantum network by using chaotic phase shifters and synchronization. Due to the orthogonality of the different chaotic phase shifter, every pair of users can faithfully transmit quantum information through a common channel and have little crosstalk between different users. Meanwhile, the broadband spectra of chaotic signals efficiently help the quantum states to defend against channel loss and noise. (paper)

  2. Providing end-to-end QoS for multimedia applications in 3G wireless networks

    Science.gov (United States)

    Guo, Katherine; Rangarajan, Samapth; Siddiqui, M. A.; Paul, Sanjoy

    2003-11-01

    As the usage of wireless packet data services increases, wireless carriers today are faced with the challenge of offering multimedia applications with QoS requirements within current 3G data networks. End-to-end QoS requires support at the application, network, link and medium access control (MAC) layers. We discuss existing CDMA2000 network architecture and show its shortcomings that prevent supporting multiple classes of traffic at the Radio Access Network (RAN). We then propose changes in RAN within the standards framework that enable support for multiple traffic classes. In addition, we discuss how Session Initiation Protocol (SIP) can be augmented with QoS signaling for supporting end-to-end QoS. We also review state of the art scheduling algorithms at the base station and provide possible extensions to these algorithms to support different classes of traffic as well as different classes of users.

  3. IAS telecommunication infrastructure and value added network services provided by IASNET

    Science.gov (United States)

    Smirnov, Oleg L.; Marchenko, Sergei

    The topology of a packet switching network for the Soviet National Centre for Automated Data Exchange with Foreign Computer Networks and Databanks (NCADE) based on a design by the Institute for Automated Systems (IAS) is discussed. NCADE has partners all over the world: it is linked to East European countries via telephone lines while satellites are used for communication with remote partners, such as Cuba, Mongolia, and Vietnam. Moreover, there is a connection to the Austrian, British, Canadian, Finnish, French, U.S. and other western networks through which users can have access to databases on each network. At the same time, NCADE provides western customers with access to more than 70 Soviet databases. Software and hardware of IASNET use data exchange recommendations agreed with the International Standard Organization (ISO) and International Telegraph and Telephone Consultative Committee (CCITT). Technical parameters of IASNET are compatible with the majority of foreign networks such as DATAPAK, TRANSPAC, TELENET, and others. By means of IASNET, the NCADE provides connection of Soviet and foreign users to information and computer centers around the world on the basis of the CCITT X.25 and X.75 recommendations. Any information resources of IASNET and value added network services, such as computer teleconferences, E-mail, information retrieval system, intelligent support of access to databanks and databases, and others are discussed. The topology of the ACADEMNET connected to IASNET over an X.25 gateway is also discussed.

  4. On the Need of Novel Medium Access Control Schemes for Network Coding enabled Wireless Mesh Networks

    DEFF Research Database (Denmark)

    Paramanathan, Achuthan; Pahlevani, Peyman; Roetter, Daniel Enrique Lucani

    2013-01-01

    that network coding will improve the throughput in such systems, but our novel medium access scheme improves the performance in the cross topology by another 66 % for network coding and 150 % for classical forwarding in theory. These gains translate in a theoretical gain of 33 % of network coding over...

  5. Hopping control channel MAC protocol for opportunistic spectrum access networks

    Institute of Scientific and Technical Information of China (English)

    FU Jing-tuan; JI Hong; MAO Xu

    2010-01-01

    Opportunistic spectrum access (OSA) is considered as a promising approach to mitigate spectrum scarcity by allowing unlicensed users to exploit spectrum opportunities in licensed frequency bands. Derived from the existing channel-hopping multiple access (CHMA) protocol,we introduce a hopping control channel medium access control (MAC) protocol in the context of OSA networks. In our proposed protocol,all nodes in the network follow a common channel-hopping sequence; every frequency channel can be used as control channel and data channel. Considering primary users' occupancy of the channel,we use a primary user (PU) detection model to calculate the channel availability for unlicensed users' access. Then,a discrete Markov chain analytical model is applied to describe the channel states and deduce the system throughput. Through simulation,we present numerical results to demonstrate the throughput performance of our protocol and thus validate our work.

  6. Optical fiber cabling technologies for flexible access network

    Science.gov (United States)

    Tanji, Hisashi

    2008-07-01

    Fiber-to-the-home (FTTH) outside plant infrastructure should be so designed and constructed as to flexibly deal with increasing subscribers and system evolution to be expected in the future, taking minimization of total cost (CAPEX and OPEX) into consideration. With this in mind, fiber access architectures are reviewed and key technologies on optical fiber and cable for supporting flexible access network are presented. Low loss over wide wavelength (low water peak) and bend-insensitive single mode fiber is a future proof solution. Enhanced separable ribbon facilitates mid-span access to individual fibers in a cable installed, improving fiber utilizing efficiency and flexibility of distribution design. It also contributes to an excellent low PMD characteristic which could be required for video RF overlay system or high capacity long reach metro-access convergence network in the future. Bend-insensitive fiber based cabling technique including field installable connector greatly improves fiber/cable handling in installation and maintenance work.

  7. High Dimensional Modulation and MIMO Techniques for Access Networks

    DEFF Research Database (Denmark)

    Binti Othman, Maisara

    Exploration of advanced modulation formats and multiplexing techniques for next generation optical access networks are of interest as promising solutions for delivering multiple services to end-users. This thesis addresses this from two different angles: high dimensionality carrierless...... the capacity per wavelength of the femto-cell network. Bit rate up to 1.59 Gbps with fiber-wireless transmission over 1 m air distance is demonstrated. The results presented in this thesis demonstrate the feasibility of high dimensionality CAP in increasing the number of dimensions and their potentially......) optical access network. 2 X 2 MIMO RoF employing orthogonal frequency division multiplexing (OFDM) with 5.6 GHz RoF signaling over all-vertical cavity surface emitting lasers (VCSEL) WDM passive optical networks (PONs). We have employed polarization division multiplexing (PDM) to further increase...

  8. Understanding the tariff. Access to the public power transportation network

    International Nuclear Information System (INIS)

    2002-01-01

    Since the European directive of December 19, 1996 about the common rules of the European power market, the eligible companies can chose their power supplier anywhere in Europe. The manager of the French power transportation network (RTE) supplies a network access to these companies according to a tariff fixed by the decree no. 2002-1014 from July 19, 2002. The aim of this document is to explain this tariff: tariffing principles ('mail-stamp' principle, voltage domain, subscribed output power tariffs, input power tariffs), tariffing elements (access to the grid, elements of output tariffs (subscribed power, overload, emergency tariffs, modifications etc..)), invoicing modalities, output tariffs, definitions. (J.S.)

  9. Wireless ad hoc networks access for aeronautical communications

    OpenAIRE

    Besse , Frédéric; Garcia , Fabien; Pirovano , Alain; Radzik , José

    2010-01-01

    International audience; There is an increasing interest in the current aeronautical context to offer new services for civil aircraft passengers. For example, airlines want to offer their customers the opportunity to access the Internet, to manage their mails, to watch video on demand, to access corporate VPNs.... All these services represent a new type of air-ground communications called APC (Aeronautical Passenger Communications) in the ATN (Aeronautical Telecommunication Network) context. I...

  10. Dynamic Resource Allocation in Hybrid Access Femtocell Network

    Directory of Open Access Journals (Sweden)

    Afaz Uddin Ahmed

    2014-01-01

    Full Text Available Intercell interference is one of the most challenging issues in femtocell deployment under the coverage of existing macrocell. Allocation of resources between femtocell and macrocell is essential to counter the effects of interference in dense femtocell networks. Advances in resource management strategies have improved the control mechanism for interference reduction at lower node density, but most of them are ineffective at higher node density. In this paper, a dynamic resource allocation management algorithm (DRAMA for spectrum shared hybrid access OFDMA femtocell network is proposed. To reduce the macro-femto-tier interference and to improve the quality of service, the proposed algorithm features a dynamic resource allocation scheme by controlling them both centrally and locally. The proposed scheme focuses on Femtocell Access Point (FAP owners’ satisfaction and allows maximum utilization of available resources based on congestion in the network. A simulation environment is developed to study the quantitative performance of DRAMA in hybrid access-control femtocell network and compare it to closed and open access mechanisms. The performance analysis shows that higher number of random users gets connected to the FAP without compromising FAP owners’ satisfaction allowing the macrocell to offload a large number of users in a dense heterogeneous network.

  11. EAP-Kerberos: A Low Latency EAP Authentication Method for Faster Handoffs in Wireless Access Networks

    Science.gov (United States)

    Zrelli, Saber; Okabe, Nobuo; Shinoda, Yoichi

    The wireless medium is a key technology for enabling ubiquitous and continuous network connectivity. It is becoming more and more important in our daily life especially with the increasing adoption of networking technologies in many fields such as medical care and transportation systems. Although most wireless technologies nowadays provide satisfying bandwidth and higher speeds, several of these technologies still lack improvements with regard to handoff performance. In this paper, we focus on wireless network technologies that rely on the Extensible Authentication Protocol for mutual authentication between the station and the access network. Such technologies include local area wireless networks (IEEE 802.11) as well as broadband wireless networks (IEEE 802.16). We present a new EAP authentication method based on a three party authentication scheme, namely Kerberos, that considerably shortens handoff delays. Compared to other methods, the proposed method has the advantage of not requiring any changes on the access points, making it readily deployable at reasonable costs.

  12. Dual-mode ultraflow access networks: a hybrid solution for the access bottleneck

    Science.gov (United States)

    Kazovsky, Leonid G.; Shen, Thomas Shunrong; Dhaini, Ahmad R.; Yin, Shuang; De Leenheer, Marc; Detwiler, Benjamin A.

    2013-12-01

    Optical Flow Switching (OFS) is a promising solution for large Internet data transfers. In this paper, we introduce UltraFlow Access, a novel optical access network architecture that offers dual-mode service to its end-users: IP and OFS. With UltraFlow Access, we design and implement a new dual-mode control plane and a new dual-mode network stack to ensure efficient connection setup and reliable and optimal data transmission. We study the impact of the UltraFlow system's design on the network throughput. Our experimental results show that with an optimized system design, near optimal (around 10 Gb/s) OFS data throughput can be attained when the line rate is 10Gb/s.

  13. A Comparative Study of Multiplexing Schemes for Next Generation Optical Access Networks

    Science.gov (United States)

    Imtiaz, Waqas A.; Khan, Yousaf; Shah, Pir Mehar Ali; Zeeshan, M.

    2014-09-01

    Passive optical network (PON) is a high bandwidth, economical solution which can provide the necessary bandwidth to end-users. Wavelength division multiplexed passive optical networks (WDM PONs) and time division multiplexed passive optical networks (TDM PONs) are considered as an evolutionary step for next-generation optical access (NGOA) networks. However they fail to provide highest transmission capacity, efficient bandwidth access, and robust dispersion tolerance. Thus future PONs are considered on simpler, efficient and potentially scalable, optical code division multiplexed (OCDM) PONs. This paper compares the performance of existing PONs with OCDM PON to determine a suitable scheme for NGOA networks. Two system parameter are used in this paper: fiber length, and bit rate. Performance analysis using Optisystem shows that; for a sufficient system performance parameters i.e. bit error rate (BER) ≤ 10-9, and maximum quality factor (Q) ≥ 6, OCDMA PON efficiently performs upto 50 km with 10 Gbit/s per ONU.

  14. ALPHA: Proposal of Mapping QoS Parameters between UPnP Home Network and GMPLS Access

    DEFF Research Database (Denmark)

    Brewka, Lukasz Jerzy; Sköldström, Pontus; Gavler, Anders

    2011-01-01

    This paper is treating the interdomain QoS signaling between the home and access domains with a focus on applying it for providing QoS between a UPnP-QoS based home network and GMPLS based access network. The work presented here is defining a possible approach for an interface between UPn...

  15. Network Layer Protocol Activation for Packet Data Access in UMTS WCDMA Laboratory Network

    OpenAIRE

    Lakkisto, Erkka

    2011-01-01

    The purpose of this Bachelor’s Thesis was to set up the UMTS WCDMA network in the laboratory environment of Helsinki Metropolia University of Applied Sciences and to study the network layer protocol activation for packet data access. The development of 3G technology has been very rapid and it can be considered as one of the main technologies in telecommunication. Implementing the laboratory network in Metropolia enables teaching and researching of the modern network technology. Labora...

  16. Modified network simulation model with token method of bus access

    Directory of Open Access Journals (Sweden)

    L.V. Stribulevich

    2013-08-01

    Full Text Available Purpose. To study the characteristics of the local network with the marker method of access to the bus its modified simulation model was developed. Methodology. Defining characteristics of the network is carried out on the developed simulation model, which is based on the state diagram-layer network station with the mechanism of processing priorities, both in steady state and in the performance of control procedures: the initiation of a logical ring, the entrance and exit of the station network with a logical ring. Findings. A simulation model, on the basis of which can be obtained the dependencies of the application the maximum waiting time in the queue for different classes of access, and the reaction time usable bandwidth on the data rate, the number of network stations, the generation rate applications, the number of frames transmitted per token holding time, frame length was developed. Originality. The technique of network simulation reflecting its work in the steady condition and during the control procedures, the mechanism of priority ranking and handling was proposed. Practical value. Defining network characteristics in the real-time systems on railway transport based on the developed simulation model.

  17. Adaptive spectrum decision framework for heterogeneous dynamic spectrum access networks

    CSIR Research Space (South Africa)

    Masonta, M

    2015-09-01

    Full Text Available Spectrum decision is the ability of a cognitive radio (CR) system to select the best available spectrum band to satisfy dynamic spectrum access network (DSAN) users¿ quality of service (QoS) requirements without causing harmful interference...

  18. Resource Sharing in Heterogeneous and Cloud Radio Access Networks

    DEFF Research Database (Denmark)

    Zakrzewska, Anna; Iversen, Villy Bæk

    2012-01-01

    be improved. However, we identify the benefit of individual operators and show that it’s not equal but highly depends on the initial network dimensioning. Furthermore, we demonstrate that under specific conditions the blocking probability in an area is lower than for fully accessible system and therefore...

  19. Medium Access Control in Energy Harvesting - Wireless Sensor Networks

    DEFF Research Database (Denmark)

    Fafoutis, Xenofon

    Focusing on Wireless Sensor Networks (WSN) that are powered by energy harvesting, this dissertation focuses on energy-efficient communication links between senders and receivers that are alternating between active and sleeping states of operation. In particular, the focus lies on Medium Access...

  20. Network Asymmetries and Access Pricing in Cellular Telecommunications

    NARCIS (Netherlands)

    V. Kocsis

    2005-01-01

    textabstractNetwork shares and retail prices are not symmetric in the telecommunications market with multiple bottlenecks which give rise to new questions of access fee regulation. In this paper we consider a model with two types of asymmetry arising from different entry timing, i.e. a larger

  1. Adaptive Media Access Control for Energy Harvesting - Wireless Sensor Networks

    DEFF Research Database (Denmark)

    Fafoutis, Xenofon; Dragoni, Nicola

    2012-01-01

    ODMAC (On-Demand Media Access Control) is a recently proposed MAC protocol designed to support individual duty cycles for Energy Harvesting — Wireless Sensor Networks (EH-WSNs). Individual duty cycles are vital for EH-WSNs, because they allow nodes to adapt their energy consumption to the ever-ch...

  2. Knowledge Access in Rural Inter-connected Areas Network ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Knowledge Access in Rural Inter-connected Areas Network (KariaNet) - Phase II ... and indigenous knowledge using information and communication technologies (ICTs) ... for research proposals on the aforementioned topics, action-research projects, ... Evaluating knowledge-sharing methods to improve land utilization and ...

  3. Optical CDMA and WDMA in the access network

    Science.gov (United States)

    Sargent, Edward H.; Stok, Andrew

    2003-08-01

    Optical CDMA provides one avenue to sharing the vast bandwidth of optical fiber among a number of active users in a network. In this work we address two questions central to considering the areas of applicability of CDMA in optics: (1) How do we compare fairly optical CDMA codes of different families, and what do we conclude? (2) How do we compare optical CDMA performance with that of conventional optical WDMA? To answer the first question, we present a method of comparing optical CDMA codes of different families, sizes and weights. We outline why the traditional performance metric of bit-error rate versus number of simultaneous users is lacking and propose a different performance measure -- the peak throughput normalized with respect to the size of the code. This metric is used to show that optical-orthogonal codes (OOCs) with a weight of 4 perform best at low offered loads while OOCs with weight 5 should be used at higher offered loads. By applying the technique across different families of codes, we demonstrate that multi-wavelength OOCs (MWOOCs) perform better than both OOCs (by a factor of approximately 1.25) and asymmetric prime-hop codes (by a factor of approximately 3.5), over a wide range of offered loads. In answer to the second question, we present a comparison of the performance of optical code-division multiple-access (CDMA) systems with that of a wavelength-division multiple-access (WDMA) system. The multiple-access techniques are applied in a time-slotted broadcast local-area network. The utilization, defined as the throughput per unit of time-domain bandwidth expansion, and packet delay are used as metrics of performance. When more than seven wavelengths are available, optical CDMA systems using asymmetric prime-hop codes and all-optical signal processing are shown to have higher peak utilization and lower corresponding delay than a WDMA system with the same number of wavelengths. When the encoders/decoders operate at the chip rate, the utilization

  4. Energy challenges in optical access and aggregation networks.

    Science.gov (United States)

    Kilper, Daniel C; Rastegarfar, Houman

    2016-03-06

    Scalability is a critical issue for access and aggregation networks as they must support the growth in both the size of data capacity demands and the multiplicity of access points. The number of connected devices, the Internet of Things, is growing to the tens of billions. Prevailing communication paradigms are reaching physical limitations that make continued growth problematic. Challenges are emerging in electronic and optical systems and energy increasingly plays a central role. With the spectral efficiency of optical systems approaching the Shannon limit, increasing parallelism is required to support higher capacities. For electronic systems, as the density and speed increases, the total system energy, thermal density and energy per bit are moving into regimes that become impractical to support-for example requiring single-chip processor powers above the 100 W limit common today. We examine communication network scaling and energy use from the Internet core down to the computer processor core and consider implications for optical networks. Optical switching in data centres is identified as a potential model from which scalable access and aggregation networks for the future Internet, with the application of integrated photonic devices and intelligent hybrid networking, will emerge. © 2016 The Author(s).

  5. CHOICE OF OPTION FOR IMPLEMENTATION OF THE MULTILEVEL SECURE ACCESS TO THE EXTERNAL NETWORK

    Directory of Open Access Journals (Sweden)

    V. S. Kolomoitcev

    2016-01-01

    Full Text Available We study the optimal way for design of access scheme called "Direct Connection. This scheme provides a secure access to external network resources, and consists of several groups of routers and two kinds of firewalls. The scheme is considered in view of the fact that the system has got common areas of removing threats in the channel for different means of protection. Parameters of average residence time of request in the system and its reliability were obtained for each variant of access scheme. Based on the results, comparison of the ways of design for access scheme was carried out between themselves and with the standard access scheme (with onefirewall. It was found out that design of access scheme with a single group of routers for the whole system has better performance and reliability than the other variants of "Direct Connection" access scheme.

  6. Deployment of a Testbed in a Brazilian Research Network using IPv6 and Optical Access Technologies

    Science.gov (United States)

    Martins, Luciano; Ferramola Pozzuto, João; Olimpio Tognolli, João; Chaves, Niudomar Siqueira De A.; Reggiani, Atilio Eduardo; Hortêncio, Claudio Antonio

    2012-04-01

    This article presents the implementation of a testbed and the experimental results obtained with it on the Brazilian Experimental Network of the government-sponsored "GIGA Project." The use of IPv6 integrated to current and emerging optical architectures and technologies, such as dense wavelength division multiplexing and 10-gigabit Ethernet on the core and gigabit capable passive optical network and optical distribution network on access, were tested. These protocols, architectures, and optical technologies are promising and part of a brand new worldwide technological scenario that has being fairly adopted in the networks of enterprises and providers of the world.

  7. Changing access to mental health care and social support when people living with HIV/AIDS become service providers.

    Science.gov (United States)

    Li, Alan Tai-Wai; Wales, Joshua; Wong, Josephine Pui-Hing; Owino, Maureen; Perreault, Yvette; Miao, Andrew; Maseko, Precious; Guiang, Charlie

    2015-01-01

    As people living with HIV/AIDS (PHAs) achieve more stable health, many have taken on active peer support and professional roles within AIDS service organizations. Although the increased engagement has been associated with many improved health outcomes, emerging program and research evidence have identified new challenges associated with such transition. This paper reports on the results of a qualitative interpretive study that explored the effect of this role transition on PHA service providers' access to mental health support and self care. A total of 27 PHA service providers of diverse ethno-racial backgrounds took part in the study. Results show that while role transition often improves access to financial and health-care benefits, it also leads to new stress from workload demands, emotional triggers from client's narratives, feeling of burnout from over-immersion in HIV at both personal and professional levels, and diminished self care. Barriers to seeking support included: concerns regarding confidentiality; self-imposed and enacted stigma associated with accessing mental health services; and boundary issues resulting from changes in relationships with peers and other service providers. Evolving support mechanisms included: new formal and informal peer support networks amongst colleagues or other PHA service providers to address both personal and professional challenges, and having access to professional support offered through the workplace. The findings suggest the need for increased organizational recognition of HIV support work as a form of emotional labor that places complex demands on PHA service providers. Increased access to employer-provided mental health services, supportive workplace policies, and adequate job-specific training will contribute to reduced work-related stress. Community level strategies that support expansion of social networks amongst PHA service providers would reduce isolation. Systemic policies to increase access to insurance

  8. The cingulo-opercular network provides word-recognition benefit.

    Science.gov (United States)

    Vaden, Kenneth I; Kuchinsky, Stefanie E; Cute, Stephanie L; Ahlstrom, Jayne B; Dubno, Judy R; Eckert, Mark A

    2013-11-27

    Recognizing speech in difficult listening conditions requires considerable focus of attention that is often demonstrated by elevated activity in putative attention systems, including the cingulo-opercular network. We tested the prediction that elevated cingulo-opercular activity provides word-recognition benefit on a subsequent trial. Eighteen healthy, normal-hearing adults (10 females; aged 20-38 years) performed word recognition (120 trials) in multi-talker babble at +3 and +10 dB signal-to-noise ratios during a sparse sampling functional magnetic resonance imaging (fMRI) experiment. Blood oxygen level-dependent (BOLD) contrast was elevated in the anterior cingulate cortex, anterior insula, and frontal operculum in response to poorer speech intelligibility and response errors. These brain regions exhibited significantly greater correlated activity during word recognition compared with rest, supporting the premise that word-recognition demands increased the coherence of cingulo-opercular network activity. Consistent with an adaptive control network explanation, general linear mixed model analyses demonstrated that increased magnitude and extent of cingulo-opercular network activity was significantly associated with correct word recognition on subsequent trials. These results indicate that elevated cingulo-opercular network activity is not simply a reflection of poor performance or error but also supports word recognition in difficult listening conditions.

  9. Greening radio access networks using distributed base station architectures

    DEFF Research Database (Denmark)

    Kardaras, Georgios; Soler, José; Dittmann, Lars

    2010-01-01

    Several actions for developing environmentally friendly technologies have been taken in most industrial fields. Significant resources have also been devoted in mobile communications industry. Moving towards eco-friendly alternatives is primarily a social responsibility for network operators....... However besides this, increasing energy efficiency represents a key factor for reducing operating expenses and deploying cost effective mobile networks. This paper presents how distributed base station architectures can contribute in greening radio access networks. More specifically, the advantages...... energy saving. Different subsystems have to be coordinated real-time and intelligent network nodes supporting complicated functionalities are necessary. Distributed base station architectures are ideal for this purpose mainly because of their high degree of configurability and self...

  10. Access pricing for transmission networks: Hypotheses and empirical evidence

    Energy Technology Data Exchange (ETDEWEB)

    Martoccia, Maria [Decision Technology Centre, London (United Kingdom)

    1999-08-01

    The sectors characterised by the use of transmission or transport networks as inputs of production (electricity, gas, telecommunications) have long been considered as natural monopolies. Thanks to the technological innovations which have modified the economics of production (as in electricity generation) or that have driven the development of high value added services (as in telecommunications), the boundaries of the old natural monopolies have been eroded by the presence of operators potentially able to compete in national and international markets. The objective is to delineate, by analysing the more significant theoretical contributions and some of the restructuring experiences of the sector in question, the possible regulatory solutions which, in the perspective of a `European market` for electricity, makes the management and the expansion of the transmission networks adequate for the `open access` of national electricity sectors. The analysis of some mature experiences, such as in Chile, Argentina, the UK and Norway, in the second section, will offer a useful support to this evaluation. The regulatory solution here adopted will be analysed, in particular, with reference to the two main problems outlined above: on the one hand, the problem of providing through prices the necessary information about the opportunities of using the transmission assets; and on the other hand, the problem of defining an efficient incentive mechanism for the behaviour of the monopolist (the owner of the transmission assets). Finally, by considering the limits found in the solutions explored in these models, we will try, in the third section, to delineate the evolution that the regulation of the analysed sectors could follow, in an attempt to make the optimal solution defined in the first section consistent with the imperfections of the real scenarios. (EHS)

  11. Social network analysis provides insights into African swine fever epidemiology.

    Science.gov (United States)

    Lichoti, Jacqueline Kasiiti; Davies, Jocelyn; Kitala, Philip M; Githigia, Samuel M; Okoth, Edward; Maru, Yiheyis; Bukachi, Salome A; Bishop, Richard P

    2016-04-01

    Pig movements play a significant role in the spread of economically important infectious diseases such as the African swine fever. Characterization of movement networks between pig farms and through other types of farm and household enterprises that are involved in pig value chains can provide useful information on the role that different participants in the networks play in pathogen transmission. Analysis of social networks that underpin these pig movements can reveal pathways that are important in the transmission of disease, trade in commodities, the dissemination of information and the influence of behavioural norms. We assessed pig movements among pig keeping households within West Kenya and East Uganda and across the shared Kenya-Uganda border in the study region, to gain insight into within-country and trans-boundary pig movements. Villages were sampled using a randomized cluster design. Data were collected through interviews in 2012 and 2013 from 683 smallholder pig-keeping households in 34 villages. NodeXL software was used to describe pig movement networks at village level. The pig movement and trade networks were localized and based on close social networks involving family ties, friendships and relationships with neighbours. Pig movement network modularity ranged from 0.2 to 0.5 and exhibited good community structure within the network implying an easy flow of knowledge and adoption of new attitudes and beliefs, but also promoting an enhanced rate of disease transmission. The average path length of 5 defined using NodeXL, indicated that disease could easily reach every node in a cluster. Cross-border boar service between Uganda and Kenya was also recorded. Unmonitored trade in both directions was prevalent. While most pig transactions in the absence of disease, were at a small scale (sales during ASF outbreaks were to traders or other farmers from outside the sellers' village at a range of >10km. The close social relationships between actors in pig

  12. Highball: A high speed, reserved-access, wide area network

    Science.gov (United States)

    Mills, David L.; Boncelet, Charles G.; Elias, John G.; Schragger, Paul A.; Jackson, Alden W.

    1990-01-01

    A network architecture called Highball and a preliminary design for a prototype, wide-area data network designed to operate at speeds of 1 Gbps and beyond are described. It is intended for applications requiring high speed burst transmissions where some latency between requesting a transmission and granting the request can be anticipated and tolerated. Examples include real-time video and disk-disk transfers, national filestore access, remote sensing, and similar applications. The network nodes include an intelligent crossbar switch, but have no buffering capabilities; thus, data must be queued at the end nodes. There are no restrictions on the network topology, link speeds, or end-end protocols. The end system, nodes, and links can operate at any speed up to the limits imposed by the physical facilities. An overview of an initial design approach is presented and is intended as a benchmark upon which a detailed design can be developed. It describes the network architecture and proposed access protocols, as well as functional descriptions of the hardware and software components that could be used in a prototype implementation. It concludes with a discussion of additional issues to be resolved in continuing stages of this project.

  13. Providing the Public with Online Access to Large Bibliographic Data Bases.

    Science.gov (United States)

    Firschein, Oscar; Summit, Roger K.

    DIALOG, an interactive, computer-based information retrieval language, consists of a series of computer programs designed to make use of direct access memory devices in order to provide the user with a rapid means of identifying records within a specific memory bank. Using the system, a library user can be provided access to sixteen distinct and…

  14. Auction pricing of network access for North American railways

    DEFF Research Database (Denmark)

    Harrod, Steven

    2013-01-01

    The question of pricing train paths for "open access" railway networks in North America is discussed. An auction process is suggested as necessary to maintain transparency in the contracting process. Multiple random samples of auction pricing for a single track railway line demonstrate...... that the infrastructure entity will receive approximately 15.6% less than the true value of the contracted train paths. This loss of revenue threatens the objective of reducing government subsidy for the railway network. (C) 2012 Elsevier Ltd. All rights reserved....

  15. A Model for the Growth of Network Service Providers

    Science.gov (United States)

    2011-12-01

    Service Provider O-D Origin-Destination POP Point of Presence UCG Unilateral Connection Game xiv THIS PAGE INTENTIONALLY LEFT BLANK xv EXECUTIVE...xvi We make use of the Abilene dataset as input to the network provisioning model and assume that the NSP is new to the market and is building an...has to decide on the connections to build and the markets to serve in order to maximize its profits. The NSP makes these decisions based on the market

  16. On the Design of Energy Efficient Optical Networks with Software Defined Networking Control Across Core and Access Networks

    DEFF Research Database (Denmark)

    Wang, Jiayuan; Yan, Ying; Dittmann, Lars

    2013-01-01

    This paper presents a Software Defined Networking (SDN) control plane based on an overlay GMPLS control model. The SDN control platform manages optical core networks (WDM/DWDM networks) and the associated access networks (GPON networks), which makes it possible to gather global information...... and enable wider areas' energy efficiency networking. The energy related information of the networks and the types of the traffic flows are collected and utilized for the end-to-end QoS provision. Dynamic network simulation results show that by applying different routing algorithms according to the type...... of traffic in the core networks, the energy efficiency of the network is improved without compromising the quality of service....

  17. Quantitative analysis of access strategies to remoteinformation in network services

    DEFF Research Database (Denmark)

    Olsen, Rasmus Løvenstein; Schwefel, Hans-Peter; Hansen, Martin Bøgsted

    2006-01-01

    of analytic models to compute different performance metrics for these approaches, with special focus on the so-called mismatch probability. The results of the analytic models allow for design decisions on which strategy to implement for specific input parameters (change rate of the information element......Remote access to dynamically changing information elements is a required functionality for various network services, including routing and instances of context-sensitive networking. Three fundamentally different strategies for such access are investigated in this paper: (1) a reactive approach...... initiated by the requesting entity, and two versions of proactive approaches in which the entity that contains the information element actively propagates its changes to potential requesters, either (2) periodically or triggered by changes of the information element (3). This paper first develops a set...

  18. High-Capacity Hybrid Optical Fiber-Wireless Communications Links in Access Networks

    DEFF Research Database (Denmark)

    Pang, Xiaodan

    of broadband services access. To realize the seamless convergence between the two network segments, the lower capacity of wireless systems need to be increased to match the continuously increasing bandwidth of fiber-optic systems. The research works included in this thesis are devoted to experimental...... investigations of photonic-wireless links with record high capacities to fulfill the requirements of next generation hybrid optical fiber-wireless access networks. The main contributions of this thesis have expanded the state-of-the-art in two main areas: high speed millimeter-wave (mm-wave) communication links......Integration between fiber-optic and wireless communications systems in the "last mile" access networks is currently considered as a promising solution for both service providers and users, in terms of minimizing deployment cost, shortening upgrading period and increasing mobility and flexibility...

  19. Cognitive radio networks medium access control for coexistence of wireless systems

    CERN Document Server

    Bian, Kaigui; Gao, Bo

    2014-01-01

    This book gives a comprehensive overview of the medium access control (MAC) principles in cognitive radio networks, with a specific focus on how such MAC principles enable different wireless systems to coexist in the same spectrum band and carry out spectrum sharing.  From algorithm design to the latest developments in the standards and spectrum policy, readers will benefit from leading-edge knowledge of how cognitive radio systems coexist and share spectrum resources.  Coverage includes cognitive radio rendezvous, spectrum sharing, channel allocation, coexistence in TV white space, and coexistence of heterogeneous wireless systems.   • Provides a comprehensive reference on medium access control (MAC)-related problems in the design of cognitive radio systems and networks; • Includes detailed analysis of various coexistence problems related to medium access control in cognitive radio networks; • Reveals novel techniques for addressing the challenges of coexistence protocol design at a higher level ...

  20. Community access networks: how to connect the next billion to the ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Community access networks: how to connect the next billion to the Internet ... services is a prerequisite to sustainable socio-economic development. ... It will provide case studies and formulate recommendations with respect to ... An IDRC delegation will join international delegates and city representatives at the ICLEI World ...

  1. Monday 9 January 2006: RESTRICTED ACCESS to the Technical Network

    CERN Multimedia

    CNIC Users Exchange and IT/CS

    2005-01-01

    As of Monday 9 January 2006, Ethernet access from the general CERN network to the Technical Network (TN) will be restricted in order to improve security on the TN. As a result, all Ethernet communication between the General Purpose Network (GPN) and the TN will be filtered. Only communication lines to the general IT services such as DNS, TP, NICE, DFS, AFS, Antivirus, Linux installation servers, License servers, OracleDB, TSM backup servers and dedicated AB and TS servers on the GPN will remain open. Please make sure that all your devices are registered properly in the network database (LANDB): http://network.cern.ch/. You are encouraged to make proper use of the 'Tag' and 'Description' fields in order to identify your system later on. If your system depends on special services on the GPN or is split between the GPN and the TN, e.g. consists of devices (PCs, PLCs, VME crates, webcams, etc.) connected to both the TN and the GPN, please contact the Technical-Network.Administrator@cern.ch . They will include...

  2. Efficient traffic grooming with dynamic ONU grouping for multiple-OLT-based access network

    Science.gov (United States)

    Zhang, Shizong; Gu, Rentao; Ji, Yuefeng; Wang, Hongxiang

    2015-12-01

    Fast bandwidth growth urges large-scale high-density access scenarios, where the multiple Passive Optical Networking (PON) system clustered deployment can be adopted as an appropriate solution to fulfill the huge bandwidth demands, especially for a future 5G mobile network. However, the lack of interaction between different optical line terminals (OLTs) results in part of the bandwidth resources waste. To increase the bandwidth efficiency, as well as reduce bandwidth pressure at the edge of a network, we propose a centralized flexible PON architecture based on Time- and Wavelength-Division Multiplexing PON (TWDM PON). It can provide flexible affiliation for optical network units (ONUs) and different OLTs to support access network traffic localization. Specifically, a dynamic ONU grouping algorithm (DGA) is provided to obtain the minimal OLT outbound traffic. Simulation results show that DGA obtains an average 25.23% traffic gain increment under different OLT numbers within a small ONU number situation, and the traffic gain will increase dramatically with the increment of the ONU number. As the DGA can be deployed easily as an application running above the centralized control plane, the proposed architecture can be helpful to improve the network efficiency for future traffic-intensive access scenarios.

  3. FttC-Based Fronthaul for 5G Dense/Ultra-Dense Access Network: Performance and Costs in Realistic Scenarios

    Directory of Open Access Journals (Sweden)

    Franco Mazzenga

    2017-10-01

    Full Text Available One distinctive feature of the next 5G systems is the presence of a dense/ultra-dense wireless access network with a large number of access points (or nodes at short distances from each other. Dense/ultra-dense access networks allow for providing very high transmission capacity to terminals. However, the deployment of dense/ultra-dense networks is slowed down by the cost of the fiber-based infrastructure required to connect radio nodes to the central processing units and then to the core network. In this paper, we investigate the possibility for existing FttC access networks to provide fronthaul capabilities for dense/ultra-dense 5G wireless networks. The analysis is realistic in that it is carried out considering an actual access network scenario, i.e., the Italian FttC deployment. It is assumed that access nodes are connected to the Cabinets and to the corresponding distributors by a number of copper pairs. Different types of cities grouped in terms of population have been considered. Results focus on fronthaul transport capacity provided by the FttC network and have been expressed in terms of the available fronthaul bit rate per node and of the achievable coverage.

  4. Distributed Robust Power Minimization for the Downlink of Multi-Cloud Radio Access Networks

    KAUST Repository

    Dhifallah, Oussama Najeeb; Dahrouj, Hayssam; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2017-01-01

    Conventional cloud radio access networks assume single cloud processing and treat inter-cloud interference as background noise. This paper considers the downlink of a multi-cloud radio access network (CRAN) where each cloud is connected to several

  5. Joint Hybrid Backhaul and Access Links Design in Cloud-Radio Access Networks

    KAUST Repository

    Dhifallah, Oussama Najeeb

    2015-09-06

    The cloud-radio access network (CRAN) is expected to be the core network architecture for next generation mobile radio systems. In this paper, we consider the downlink of a CRAN formed of one central processor (the cloud) and several base station (BS), where each BS is connected to the cloud via either a wireless or capacity-limited wireline backhaul link. The paper addresses the joint design of the hybrid backhaul links (i.e., designing the wireline and wireless backhaul connections from the cloud to the BSs) and the access links (i.e., determining the sparse beamforming solution from the BSs to the users). The paper formulates the hybrid backhaul and access link design problem by minimizing the total network power consumption. The paper solves the problem using a two-stage heuristic algorithm. At one stage, the sparse beamforming solution is found using a weighted mixed 11/12 norm minimization approach; the correlation matrix of the quantization noise of the wireline backhaul links is computed using the classical rate-distortion theory. At the second stage, the transmit powers of the wireless backhaul links are found by solving a power minimization problem subject to quality-of-service constraints, based on the principle of conservation of rate by utilizing the rates found in the first stage. Simulation results suggest that the performance of the proposed algorithm approaches the global optimum solution, especially at high signal-to-interference-plus-noise ratio (SINR).

  6. Providing Internet Access to the Ohio Career Information System for All Residents: A Feasibility Study.

    Science.gov (United States)

    Lewis, Morgan V.

    Expanded Internet access to the Ohio Career Information System (OCIS) would provide adults in Ohio who need to or wish to make career changes with the best available information about occupations, education and training programs, and financial aid. In order to determine the feasibility of improving access without cost to users, an advisory group,…

  7. Providing Social Enterprises with Better Access to Public Procurement : The Development of Supportive Legal Frameworks

    NARCIS (Netherlands)

    Argyrou, A.

    2017-01-01

    This article discusses the issue of social enterprises gaining access to public procurement processes and contracts at the EU and national level. It primarily examines the opportunities for social enterprises to access public procurement contracts provided for in the Public Procurement Directive

  8. A Novel Dynamic Spectrum Access Framework Based on Reinforcement Learning for Cognitive Radio Sensor Networks

    Directory of Open Access Journals (Sweden)

    Yun Lin

    2016-10-01

    Full Text Available Cognitive radio sensor networks are one of the kinds of application where cognitive techniques can be adopted and have many potential applications, challenges and future research trends. According to the research surveys, dynamic spectrum access is an important and necessary technology for future cognitive sensor networks. Traditional methods of dynamic spectrum access are based on spectrum holes and they have some drawbacks, such as low accessibility and high interruptibility, which negatively affect the transmission performance of the sensor networks. To address this problem, in this paper a new initialization mechanism is proposed to establish a communication link and set up a sensor network without adopting spectrum holes to convey control information. Specifically, firstly a transmission channel model for analyzing the maximum accessible capacity for three different polices in a fading environment is discussed. Secondly, a hybrid spectrum access algorithm based on a reinforcement learning model is proposed for the power allocation problem of both the transmission channel and the control channel. Finally, extensive simulations have been conducted and simulation results show that this new algorithm provides a significant improvement in terms of the tradeoff between the control channel reliability and the efficiency of the transmission channel.

  9. Extending AAA operational model for profile-based access control in ethernet-based Neutral Access Networks

    NARCIS (Netherlands)

    Matias, J.; Jacob, E.; Demchenko, Y.; de Laat, C.; Gommans, L.; Macías López, E.M.; Bogliolo, A.; Perry, M.; Ran, M

    2010-01-01

    Neutral Access Networks (NAN) have appeared as a new model to overcome some restrictions and lack of flexibility that are present currently in broadband access networks. NAN brings new business opportunities by opening this market to new stakeholders. Although the NAN model is accepted, there are

  10. Providers' Access of Imaging Versus Only Reports: A System Log File Analysis.

    Science.gov (United States)

    Jung, Hye-Young; Gichoya, Judy Wawira; Vest, Joshua R

    2017-02-01

    An increasing number of technologies allow providers to access the results of imaging studies. This study examined differences in access of radiology images compared with text-only reports through a health information exchange system by health care professionals. The study sample included 157,256 historical sessions from a health information exchange system that enabled 1,670 physicians and non-physicians to access text-based reports and imaging over the period 2013 to 2014. The primary outcome was an indicator of access of an imaging study instead of access of a text-only report. Multilevel mixed-effects regression models were used to estimate the association between provider and session characteristics and access of images compared with text-only reports. Compared with primary care physicians, specialists had an 18% higher probability of accessing actual images instead of text-only reports (β = 0.18; P < .001). Compared with primary care practice settings, the probability of accessing images was 4% higher for specialty care practices (P < .05) and 8% lower for emergency departments (P < .05). Radiologists, orthopedists, and neurologists accounted for 79% of all the sessions with actual images accessed. Orthopedists, radiologists, surgeons, and pulmonary disease specialists accessed imaging more often than text-based reports only. Consideration for differences in the need to access images compared with text-only reports based on the type of provider and setting of care are needed to maximize the benefits of image sharing for patient care. Copyright © 2016 American College of Radiology. Published by Elsevier Inc. All rights reserved.

  11. Downlink Non-Orthogonal Multiple Access (NOMA) in Poisson Networks

    KAUST Repository

    Ali, Konpal S.

    2018-03-21

    A network model is considered where Poisson distributed base stations transmit to $N$ power-domain non-orthogonal multiple access (NOMA) users (UEs) each that employ successive interference cancellation (SIC) for decoding. We propose three models for the clustering of NOMA UEs and consider two different ordering techniques for the NOMA UEs: mean signal power-based and instantaneous signal-to-intercell-interference-and-noise-ratio-based. For each technique, we present a signal-to-interference-and-noise ratio analysis for the coverage of the typical UE. We plot the rate region for the two-user case and show that neither ordering technique is consistently superior to the other. We propose two efficient algorithms for finding a feasible resource allocation that maximize the cell sum rate $\\\\mathcal{R}_{\\ m tot}$, for general $N$, constrained to: 1) a minimum rate $\\\\mathcal{T}$ for each UE, 2) identical rates for all UEs. We show the existence of: 1) an optimum $N$ that maximizes the constrained $\\\\mathcal{R}_{\\ m tot}$ given a set of network parameters, 2) a critical SIC level necessary for NOMA to outperform orthogonal multiple access. The results highlight the importance in choosing the network parameters $N$, the constraints, and the ordering technique to balance the $\\\\mathcal{R}_{\\ m tot}$ and fairness requirements. We also show that interference-aware UE clustering can significantly improve performance.

  12. Non-Orthogonal Multiple Access for Ubiquitous Wireless Sensor Networks.

    Science.gov (United States)

    Anwar, Asim; Seet, Boon-Chong; Ding, Zhiguo

    2018-02-08

    Ubiquitous wireless sensor networks (UWSNs) have become a critical technology for enabling smart cities and other ubiquitous monitoring applications. Their deployment, however, can be seriously hampered by the spectrum available to the sheer number of sensors for communication. To support the communication needs of UWSNs without requiring more spectrum resources, the power-domain non-orthogonal multiple access (NOMA) technique originally proposed for 5th Generation (5G) cellular networks is investigated for UWSNs for the first time in this paper. However, unlike 5G networks that operate in the licensed spectrum, UWSNs mostly operate in unlicensed spectrum where sensors also experience cross-technology interferences from other devices sharing the same spectrum. In this paper, we model the interferences from various sources at the sensors using stochastic geometry framework. To evaluate the performance, we derive a theorem and present new closed form expression for the outage probability of the sensors in a downlink scenario under interference limited environment. In addition, diversity analysis for the ordered NOMA users is performed. Based on the derived outage probability, we evaluate the average link throughput and energy consumption efficiency of NOMA against conventional orthogonal multiple access (OMA) technique in UWSNs. Further, the required computational complexity for the NOMA users is presented.

  13. Downlink Non-Orthogonal Multiple Access (NOMA) in Poisson Networks

    KAUST Repository

    Ali, Konpal S.; Haenggi, Martin; Elsawy, Hesham; Chaaban, Anas; Alouini, Mohamed-Slim

    2018-01-01

    A network model is considered where Poisson distributed base stations transmit to $N$ power-domain non-orthogonal multiple access (NOMA) users (UEs) each that employ successive interference cancellation (SIC) for decoding. We propose three models for the clustering of NOMA UEs and consider two different ordering techniques for the NOMA UEs: mean signal power-based and instantaneous signal-to-intercell-interference-and-noise-ratio-based. For each technique, we present a signal-to-interference-and-noise ratio analysis for the coverage of the typical UE. We plot the rate region for the two-user case and show that neither ordering technique is consistently superior to the other. We propose two efficient algorithms for finding a feasible resource allocation that maximize the cell sum rate $\\mathcal{R}_{\\rm tot}$, for general $N$, constrained to: 1) a minimum rate $\\mathcal{T}$ for each UE, 2) identical rates for all UEs. We show the existence of: 1) an optimum $N$ that maximizes the constrained $\\mathcal{R}_{\\rm tot}$ given a set of network parameters, 2) a critical SIC level necessary for NOMA to outperform orthogonal multiple access. The results highlight the importance in choosing the network parameters $N$, the constraints, and the ordering technique to balance the $\\mathcal{R}_{\\rm tot}$ and fairness requirements. We also show that interference-aware UE clustering can significantly improve performance.

  14. Modeling Accessibility of Screening and Treatment Facilities for Older Adults using Transportation Networks.

    Science.gov (United States)

    Zhang, Qiuyi; Northridge, Mary E; Jin, Zhu; Metcalf, Sara S

    2018-04-01

    Increased lifespans and population growth have resulted in an older U.S. society that must reckon with the complex oral health needs that arise as adults age. Understanding accessibility to screening and treatment facilities for older adults is necessary in order to provide them with preventive and restorative services. This study uses an agent-based model to examine the accessibility of screening and treatment facilities via transportation networks for older adults living in the neighborhoods of northern Manhattan, New York City. Older adults are simulated as socioeconomically distinct agents who move along a GIS-based transportation network using transportation modes that mediate their access to screening and treatment facilities. This simulation model includes four types of mobile agents as a simplifying assumption: walk, by car, by bus, or by van (i.e., a form of transportation assistance for older adults). These mobile agents follow particular routes: older adults who travel by car, bus, and van follow street roads, whereas pedestrians follow walkways. The model enables the user to focus on one neighborhood at a time for analysis. The spatial dimension of an older adult's accessibility to screening and treatment facilities is simulated through the travel costs (indicated by travel time or distance) incurred in the GIS-based model environment, where lower travel costs to screening and treatment facilities imply better access. This model provides a framework for representing health-seeking behavior that is contextualized by a transportation network in a GIS environment.

  15. The climate4impact platform: Providing, tailoring and facilitating climate model data access

    Science.gov (United States)

    Pagé, Christian; Pagani, Andrea; Plieger, Maarten; Som de Cerff, Wim; Mihajlovski, Andrej; de Vreede, Ernst; Spinuso, Alessandro; Hutjes, Ronald; de Jong, Fokke; Bärring, Lars; Vega, Manuel; Cofiño, Antonio; d'Anca, Alessandro; Fiore, Sandro; Kolax, Michael

    2017-04-01

    One of the main objectives of climate4impact is to provide standardized web services and tools that are reusable in other portals. These services include web processing services, web coverage services and web mapping services (WPS, WCS and WMS). Tailored portals can be targeted to specific communities and/or countries/regions while making use of those services. Easier access to climate data is very important for the climate change impact communities. To fulfill this objective, the climate4impact (http://climate4impact.eu/) web portal and services has been developed, targeting climate change impact modellers, impact and adaptation consultants, as well as other experts using climate change data. It provides to users harmonized access to climate model data through tailored services. It features static and dynamic documentation, Use Cases and best practice examples, an advanced search interface, an integrated authentication and authorization system with the Earth System Grid Federation (ESGF), a visualization interface with ADAGUC web mapping tools. In the latest version, statistical downscaling services, provided by the Santander Meteorology Group Downscaling Portal, were integrated. An innovative interface to integrate statistical downscaling services will be released in the upcoming version. The latter will be a big step in bridging the gap between climate scientists and the climate change impact communities. The climate4impact portal builds on the infrastructure of an international distributed database that has been set to disseminate the results from the global climate model results of the Coupled Model Intercomparison project Phase 5 (CMIP5). This database, the ESGF, is an international collaboration that develops, deploys and maintains software infrastructure for the management, dissemination, and analysis of climate model data. The European FP7 project IS-ENES, Infrastructure for the European Network for Earth System modelling, supports the European

  16. QoS Provisioning Techniques for Future Fiber-Wireless (FiWi Access Networks

    Directory of Open Access Journals (Sweden)

    Martin Maier

    2010-04-01

    Full Text Available A plethora of enabling optical and wireless access-metro network technologies have been emerging that can be used to build future-proof bimodal fiber-wireless (FiWi networks. Hybrid FiWi networks aim at providing wired and wireless quad-play services over the same infrastructure simultaneously and hold great promise to mitigate the digital divide and change the way we live and work by replacing commuting with teleworking. After overviewing enabling optical and wireless network technologies and their QoS provisioning techniques, we elaborate on enabling radio-over-fiber (RoF and radio-and-fiber (R&F technologies. We describe and investigate new QoS provisioning techniques for future FiWi networks, ranging from traffic class mapping, scheduling, and resource management to advanced aggregation techniques, congestion control, and layer-2 path selection algorithms.

  17. Convergence of broadband optical and wireless access networks

    Science.gov (United States)

    Chang, Gee-Kung; Jia, Zhensheng; Chien, Hung-Chang; Chowdhury, Arshad; Hsueh, Yu-Ting; Yu, Jianjun

    2009-01-01

    This paper describes convergence of optical and wireless access networks for delivering high-bandwidth integrated services over optical fiber and air links. Several key system technologies are proposed and experimentally demonstrated. We report here, for the first ever, a campus-wide field trial demonstration of radio-over-fiber (RoF) system transmitting uncompressed standard-definition (SD) high-definition (HD) real-time video contents, carried by 2.4-GHz radio and 60- GHz millimeter-wave signals, respectively, over 2.5-km standard single mode fiber (SMF-28) through the campus fiber network at Georgia Institute of Technology (GT). In addition, subsystem technologies of Base Station and wireless tranceivers operated at 60 GHz for real-time video distribution have been developed and tested.

  18. A Spontaneous Ad Hoc Network to Share WWW Access

    Directory of Open Access Journals (Sweden)

    Lloret Jaime

    2010-01-01

    Full Text Available In this paper, we propose a secure spontaneous ad-hoc network, based on direct peer-to-peer interaction, to grant a quick, easy, and secure access to the users to surf the Web. The paper shows the description of our proposal, the procedure of the nodes involved in the system, the security algorithms implemented, and the designed messages. We have taken into account the security and its performance. Although some people have defined and described the main features of spontaneous ad-hoc networks, nobody has published any design and simulation until today. Spontaneous networking will enable a more natural form of wireless computing when people physically meet in the real world. We also validate the success of our proposal through several simulations and comparisons with a regular architecture, taking into account the optimization of the resources of the devices. Finally, we compare our proposal with other caching techniques published in the related literature. The proposal has been developed with the main objective of improving the communication and integration between different study centers of low-resource communities. That is, it lets communicate spontaneous networks, which are working collaboratively and which have been created on different physical places.

  19. Optical code-division multiple-access networks

    Science.gov (United States)

    Andonovic, Ivan; Huang, Wei

    1999-04-01

    This review details the approaches adopted to implement classical code division multiple access (CDMA) principles directly in the optical domain, resulting in all optical derivatives of electronic systems. There are a number of ways of realizing all-optical CDMA systems, classified as incoherent and coherent based on spreading in the time and frequency dimensions. The review covers the basic principles of optical CDMA (OCDMA), the nature of the codes used in these approaches and the resultant limitations on system performance with respect to the number of stations (code cardinality), the number of simultaneous users (correlation characteristics of the families of codes), concluding with consideration of network implementation issues. The latest developments will be presented with respect to the integration of conventional time spread codes, used in the bulk of the demonstrations of these networks to date, with wavelength division concepts, commonplace in optical networking. Similarly, implementations based on coherent correlation with the aid of a local oscillator will be detailed and comparisons between approaches will be drawn. Conclusions regarding the viability of these approaches allowing the goal of a large, asynchronous high capacity optical network to be realized will be made.

  20. Networked Print Production: Does JDF Provide a Perfect Workflow?

    Directory of Open Access Journals (Sweden)

    Bernd Zipper

    2004-12-01

    Full Text Available The "networked printing works" is a well-worn slogan used by many providers in the graphics industry and for the past number of years printing-works manufacturers have been working on the goal of achieving the "networked printing works". A turning point from the concept to real implementation can now be expected at drupa 2004: JDF (Job Definition Format and thus "networked production" will form the center of interest here. The first approaches towards a complete, networked workflow between prepress, print and postpress in production are already available - the products and solutions will now be presented publicly at drupa 2004. So, drupa 2004 will undoubtedly be the "JDF-drupa" - the drupa where machines learn to communicate with each other digitally - the drupa, where the dream of general system and job communication in the printing industry can be first realized. CIP3, which has since been renamed CIP4, is an international consortium of leading manufacturers from the printing and media industry who have taken on the task of integrating processes for prepress, print and postpress. The association, to which nearly all manufacturers in the graphics industry belong, has succeeded with CIP3 in developing a first international standard for the transmission of control data in the print workflow.Further development of the CIP4 standard now includes a more extensive "system language" called JDF, which will guarantee workflow communication beyond manufacturer boundaries. However, not only data for actual print production will be communicated with JDF (Job Definition Format: planning and calculation data for MIS (Management Information systems and calculation systems will also be prepared. The German printing specialist Hans-Georg Wenke defines JDF as follows: "JDF takes over data from MIS for machines, aggregates and their control desks, data exchange within office applications, and finally ensures that data can be incorporated in the technical workflow

  1. Access to In-Network Emergency Physicians and Emergency Departments Within Federally Qualified Health Plans in 2015

    Directory of Open Access Journals (Sweden)

    Stephen C. Dorner, MSc

    2016-01-01

    Full Text Available Introduction: Under regulations established by the Affordable Care Act, insurance plans must meet minimum standards in order to be sold through the federal Marketplace. These standards to become a qualified health plan (QHP include maintaining a provider network sufficient to assure access to services. However, the complexity of emergency physician (EP employment practices – in which the EPs frequently serve as independent contractors of emergency departments, independently establish insurance contracts, etc... – and regulations governing insurance repayment may hinder the application of network adequacy standards to emergency medicine. As such, we hypothesized the existence of QHPs without in-network access to EPs. The objective is to identify whether there are QHPs without in-network access to EPs using information available through the federal Marketplace and publicly available provider directories. Results: In a national sample of Marketplace plans, we found that one in five provider networks lacks identifiable in-network EPs. QHPs lacking EPs spanned nearly half (44% of the 34 states using the federal Marketplace. Conclusion: Our data suggest that the present regulatory framework governing network adequacy is not generalizable to emergency care, representing a missed opportunity to protect patient access to in-network physicians. These findings and the current regulations governing insurance payment to EPs dis-incentivize the creation of adequate physician networks, incentivize the practice of balance billing, and shift the cost burden to patients.

  2. Incentive Mechanism for P2P Content Sharing over Heterogenous Access Networks

    Science.gov (United States)

    Sato, Kenichiro; Hashimoto, Ryo; Yoshino, Makoto; Shinkuma, Ryoichi; Takahashi, Tatsuro

    In peer-to-peer (P2P) content sharing, users can share their content by contributing their own resources to one another. However, since there is no incentive for contributing contents or resources to others, users may attempt to obtain content without any contribution. To motivate users to contribute their resources to the service, incentive-rewarding mechanisms have been proposed. On the other hand, emerging wireless technologies, such as IEEE 802.11 wireless local area networks, beyond third generation (B3G) cellular networks and mobile WiMAX, provide high-speed Internet access for wireless users. Using these high-speed wireless access, wireless users can use P2P services and share their content with other wireless users and with fixed users. However, this diversification of access networks makes it difficult to appropriately assign rewards to each user according to their contributions. This is because the cost necessary for contribution is different in different access networks. In this paper, we propose a novel incentive-rewarding mechanism called EMOTIVER that can assign rewards to users appropriately. The proposed mechanism uses an external evaluator and interactive learning agents. We also investigate a way of appropriately controlling rewards based on the system service's quality and managing policy.

  3. Association of mandated language access programming and quality of care provided by mental health agencies.

    Science.gov (United States)

    McClellan, Sean R; Snowden, Lonnie

    2015-01-01

    This study examined the association between language access programming and quality of psychiatric care received by persons with limited English proficiency (LEP). In 1999, the California Department of Mental Health required county Medicaid agencies to implement a "threshold language access policy" to meet the state's Title VI obligations. This policy required Medi-Cal agencies to provide language access programming, including access to interpreters and translated written material, to speakers of languages other than English if the language was spoken by at least 3,000, or 5%, of the county's Medicaid population. Using a longitudinal study design with a nonequivalent control group, this study examined the quality of care provided to Spanish speakers with LEP and a severe mental illness before and after implementation of mandatory language access programming. Quality was measured by receipt of at least two follow-up medication visits within 90 days or three visits within 180 days of an initial medication visit over a period of 38 quarter-years. On average, only 40% of Spanish-speaking clients received at least three medication follow-up visits within 180 days. In multivariate analyses, language access programming was not associated with receipt of at least two medication follow-up visits within 90 days or at least three visits within 180 days. This study found no evidence that language access programming led to increased rates of follow-up medication visits for clients with LEP.

  4. Technology solutions to support supervisory activities and also to provide information access to the society

    Science.gov (United States)

    Paladini, D.; Mello, A. B.

    2016-07-01

    Inmetro's data about the conformity of certificated products, process and services are, usually, displayed at fragmented databases of difficult access for several reasons, for instance, the lack of computational solutions which allow this kind of access to its users. A discussion about some of the technological solutions to support supervisory activities by the appropriate regulatory bodies and also to provide information access to society in general is herein presented, along with a theoretical explanation of the pros and cons of such technologies to the conclusion that a mobile platform seems to be the best tool for the requirements of Inmetro.

  5. Partial Interference and Its Performance Impact on Wireless Multiple Access Networks

    Directory of Open Access Journals (Sweden)

    Lau WingCheong

    2010-01-01

    Full Text Available To determine the capacity of wireless multiple access networks, the interference among the wireless links must be accurately modeled. In this paper, we formalize the notion of the partial interference phenomenon observed in many recent wireless measurement studies and establish analytical models with tractable solutions for various types of wireless multiple access networks. In particular, we characterize the stability region of IEEE 802.11 networks under partial interference with two potentially unsaturated links numerically. We also provide a closed-form solution for the stability region of slotted ALOHA networks under partial interference with two potentially unsaturated links and obtain a partial characterization of the boundary of the stability region for the general M-link case. Finally, we derive a closed-form approximated solution for the stability region for general M-link slotted ALOHA system under partial interference effects. Based on our results, we demonstrate that it is important to model the partial interference effects while analyzing wireless multiple access networks. This is because such considerations can result in not only significant quantitative differences in the predicted system capacity but also fundamental qualitative changes in the shape of the stability region of the systems.

  6. Enhancing Sensing and Channel Access in Cognitive Radio Networks

    KAUST Repository

    Hamza, Doha R.

    2014-06-18

    Cognitive radio technology is a promising technology to solve the wireless spectrum scarcity problem by intelligently allowing secondary, or unlicensed, users access to the primary, licensed, users\\' frequency bands. Cognitive technology involves two main tasks: 1) sensing the wireless medium to assess the presence of the primary users and 2) designing secondary spectrum access techniques that maximize the secondary users\\' benefits while maintaining the primary users\\' privileged status. On the spectrum sensing side, we make two contributions. First, we maximize a utility function representing the secondary throughput while constraining the collision probability with the primary below a certain value. We optimize therein the channel sensing time, the sensing decision threshold, the channel probing time, together with the channel sensing order for wideband primary channels. Second, we design a cooperative spectrum sensing technique termed sensing with equal gain combining whereby cognitive radios simultaneously transmit their sensing results to the fusion center over multipath fading reporting channels. The proposed scheme is shown to outperform orthogonal reporting systems in terms of achievable secondary throughput and to be robust against phase and synchronization errors. On the spectrum access side, we make four contributions. First, we design a secondary scheduling scheme with the goal of minimizing the secondary queueing delay under constraints on the average secondary transmit power and the maximum tolerable primary outage probability. Second, we design another secondary scheduling scheme based on the spectrum sensing results and the primary automatic repeat request feedback. The optimal medium access probabilities are obtained via maximizing the secondary throughput subject to constraints that guarantee quality of service parameters for the primary. Third, we propose a three-message superposition coding scheme to maximize the secondary throughput without

  7. Some Programs Should Not Run on Laptops - Providing Programmatic Access to Applications Via Web Services

    Science.gov (United States)

    Gupta, V.; Gupta, N.; Gupta, S.; Field, E.; Maechling, P.

    2003-12-01

    hosted these Web Services as a part of the SCEC Community Modeling Environment (SCEC/CME) ITR Project (http://www.scec.org/cme). We have implemented Web Services for several of the reasons sited previously. For example, we implemented a FORTRAN-based Earthquake Rupture Forecast (ERF) as a Web Service for use by client computers that don't support a FORTRAN runtime environment. We implemented a Generic Mapping Tool (GMT) Web Service for use by systems that don't have local access to GMT. We implemented a Hazard Map Calculator Web Service to execute Hazard calculations that are too computationally intensive to run on a local system. We implemented a Coordinate Conversion Web Service to enforce a standard and consistent method for converting between UTM and Lat/Lon. Our experience developing these services indicates both strengths and weakness in current Web Service technology. Client programs that utilize Web Services typically need network access, a significant disadvantage at times. Programs with simple input and output parameters were the easiest to implement as Web Services, while programs with complex parameter-types required a significant amount of additional development. We also noted that Web services are very data-oriented, and adapting object-oriented software into the Web Service model proved problematic. Also, the Web Service approach of converting data types into XML format for network transmission has significant inefficiencies for some data sets.

  8. Provider Perspectives on School-Based Mental Health for Urban Minority Youth: Access and Services

    Science.gov (United States)

    Gamble, Brandon E.; Lambros, Katina M.

    2014-01-01

    This article provides results from a qualitative study on the efforts of school-based mental health providers (SBMHPs) who serve students in urban, suburban, and ethnically diverse settings to help families access quality mental health services. School-based mental health plays a key role in the provision of direct and indirect intervention…

  9. Evaluation of the role of access providers. Discussion of Dutch Pirate Bay case law and introducing principles on directness, effectiveness, costs, relevance, and time

    NARCIS (Netherlands)

    Lodder, A.R.; van der Meulen, N.S.

    2013-01-01

    Internet service providers (ISPs) play a pivotal role in contemporary society because they provide access to the Internet. The primary task of ISPs – to blindly transfer information across the network – has recently come under pressure, as has their status as neutral third parties. Both the public

  10. An Adaptive Channel Access Method for Dynamic Super Dense Wireless Sensor Networks.

    Science.gov (United States)

    Lei, Chunyang; Bie, Hongxia; Fang, Gengfa; Zhang, Xuekun

    2015-12-03

    Super dense and distributed wireless sensor networks have become very popular with the development of small cell technology, Internet of Things (IoT), Machine-to-Machine (M2M) communications, Vehicular-to-Vehicular (V2V) communications and public safety networks. While densely deployed wireless networks provide one of the most important and sustainable solutions to improve the accuracy of sensing and spectral efficiency, a new channel access scheme needs to be designed to solve the channel congestion problem introduced by the high dynamics of competing nodes accessing the channel simultaneously. In this paper, we firstly analyzed the channel contention problem using a novel normalized channel contention analysis model which provides information on how to tune the contention window according to the state of channel contention. We then proposed an adaptive channel contention window tuning algorithm in which the contention window tuning rate is set dynamically based on the estimated channel contention level. Simulation results show that our proposed adaptive channel access algorithm based on fast contention window tuning can achieve more than 95 % of the theoretical optimal throughput and 0 . 97 of fairness index especially in dynamic and dense networks.

  11. An Adaptive Channel Access Method for Dynamic Super Dense Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Chunyang Lei

    2015-12-01

    Full Text Available Super dense and distributed wireless sensor networks have become very popular with the development of small cell technology, Internet of Things (IoT, Machine-to-Machine (M2M communications, Vehicular-to-Vehicular (V2V communications and public safety networks. While densely deployed wireless networks provide one of the most important and sustainable solutions to improve the accuracy of sensing and spectral efficiency, a new channel access scheme needs to be designed to solve the channel congestion problem introduced by the high dynamics of competing nodes accessing the channel simultaneously. In this paper, we firstly analyzed the channel contention problem using a novel normalized channel contention analysis model which provides information on how to tune the contention window according to the state of channel contention. We then proposed an adaptive channel contention window tuning algorithm in which the contention window tuning rate is set dynamically based on the estimated channel contention level. Simulation results show that our proposed adaptive channel access algorithm based on fast contention window tuning can achieve more than 95 % of the theoretical optimal throughput and 0 . 97 of fairness index especially in dynamic and dense networks.

  12. SON for LTE-WLAN access network selection : design and performance

    NARCIS (Netherlands)

    Willemen, P.; Laselva, D.; Wang, Y.; Kovács, I.; Djapic, R.; Moerman, I.

    2016-01-01

    Mobile network operators (MNOs) are deploying carrier-grade Wireless Local Area Network (WLAN) as an important complementary system to cellular networks. Access network selection (ANS) between cellular and WLAN is an essential component to improve network performance and user quality-of-service

  13. Performance of WLAN RSS-based SON for LTE/WLAN access network selection

    NARCIS (Netherlands)

    Wang, Y.; Djapic, R.; Bergström, A.; Kovács, I.Z.; Laselva, D.; Spaey, K.; Sas, B.

    2014-01-01

    Mobile Network Operators (MNOs) are integrating carrier-grade Wireless Local Area Network (WLAN) to cellular networks to improve network performance and user experience. Access network selection (ANS) between cellular and WLAN plays a key role in the integration. Given the complexity of

  14. Experimental demonstration of large capacity WSDM optical access network with multicore fibers and advanced modulation formats.

    Science.gov (United States)

    Li, Borui; Feng, Zhenhua; Tang, Ming; Xu, Zhilin; Fu, Songnian; Wu, Qiong; Deng, Lei; Tong, Weijun; Liu, Shuang; Shum, Perry Ping

    2015-05-04

    Towards the next generation optical access network supporting large capacity data transmission to enormous number of users covering a wider area, we proposed a hybrid wavelength-space division multiplexing (WSDM) optical access network architecture utilizing multicore fibers with advanced modulation formats. As a proof of concept, we experimentally demonstrated a WSDM optical access network with duplex transmission using our developed and fabricated multicore (7-core) fibers with 58.7km distance. As a cost-effective modulation scheme for access network, the optical OFDM-QPSK signal has been intensity modulated on the downstream transmission in the optical line terminal (OLT) and it was directly detected in the optical network unit (ONU) after MCF transmission. 10 wavelengths with 25GHz channel spacing from an optical comb generator are employed and each wavelength is loaded with 5Gb/s OFDM-QPSK signal. After amplification, power splitting, and fan-in multiplexer, 10-wavelength downstream signal was injected into six outer layer cores simultaneously and the aggregation downstream capacity reaches 300 Gb/s. -16 dBm sensitivity has been achieved for 3.8 × 10-3 bit error ratio (BER) with 7% Forward Error Correction (FEC) limit for all wavelengths in every core. Upstream signal from ONU side has also been generated and the bidirectional transmission in the same core causes negligible performance degradation to the downstream signal. As a universal platform for wired/wireless data access, our proposed architecture provides additional dimension for high speed mobile signal transmission and we hence demonstrated an upstream delivery of 20Gb/s per wavelength with QPSK modulation formats using the inner core of MCF emulating a mobile backhaul service. The IQ modulated data was coherently detected in the OLT side. -19 dBm sensitivity has been achieved under the FEC limit and more than 18 dB power budget is guaranteed.

  15. Network Physics anounces first product to provide business-level management of the most complex and dynamic networks

    CERN Multimedia

    2003-01-01

    Network Physics, provider of business-level, traffic flow-based network management solutions, today announced the introduction of the Network Physics NP/BizFlow-1000. With the NP/BizFlow-1000, Fortune 1000 companies with complex and dynamic networks can analyze the flows that link business groups, critical applications, and network software and hardware (1 page).

  16. A novel and efficient user access control scheme for wireless body area sensor networks

    Directory of Open Access Journals (Sweden)

    Santanu Chatterjee

    2014-07-01

    Full Text Available Wireless body area networks (WBANs can be applied to provide healthcare and patient monitoring. However, patient privacy can be vulnerable in a WBAN unless security is considered. Access to authorized users for the correct information and resources for different services can be provided with the help of efficient user access control mechanisms. This paper proposes a new user access control scheme for a WBAN. The proposed scheme makes use of a group-based user access ID, an access privilege mask, and a password. An elliptic curve cryptography-based public key cryptosystem is used to ensure that a particular legitimate user can only access the information for which he/she is authorized. We show that our scheme performs better than previously existing user access control schemes. Through a security analysis, we show that our scheme is secure against possible known attacks. Furthermore, through a formal security verification using the AVISPA (Automated Validation of Internet Security Protocols and Applications tool, we show that our scheme is also secure against passive and active attacks.

  17. PANATIKI: A Network Access Control Implementation Based on PANA for IoT Devices

    Directory of Open Access Journals (Sweden)

    Antonio F. Gomez Skarmeta

    2013-11-01

    Full Text Available Internet of Things (IoT networks are the pillar of recent novel scenarios, such as smart cities or e-healthcare applications. Among other challenges, these networks cover the deployment and interaction of small devices with constrained capabilities and Internet protocol (IP-based networking connectivity. These constrained devices usually require connection to the Internet to exchange information (e.g., management or sensing data or access network services. However, only authenticated and authorized devices can, in general, establish this connection. The so-called authentication, authorization and accounting (AAA services are in charge of performing these tasks on the Internet. Thus, it is necessary to deploy protocols that allow constrained devices to verify their credentials against AAA infrastructures. The Protocol for Carrying Authentication for Network Access (PANA has been standardized by the Internet engineering task force (IETF to carry the Extensible Authentication Protocol (EAP, which provides flexible authentication upon the presence of AAA. To the best of our knowledge, this paper is the first deep study of the feasibility of EAP/PANA for network access control in constrained devices. We provide light-weight versions and implementations of these protocols to fit them into constrained devices. These versions have been designed to reduce the impact in standard specifications. The goal of this work is two-fold: (1 to demonstrate the feasibility of EAP/PANA in IoT devices; (2 to provide the scientific community with the first light-weight interoperable implementation of EAP/PANA for constrained devices in the Contiki operating system (Contiki OS, called PANATIKI. The paper also shows a testbed, simulations and experimental results obtained from real and simulated constrained devices.

  18. PANATIKI: a network access control implementation based on PANA for IoT devices.

    Science.gov (United States)

    Moreno Sanchez, Pedro; Marin Lopez, Rafa; Gomez Skarmeta, Antonio F

    2013-11-01

    Internet of Things (IoT) networks are the pillar of recent novel scenarios, such as smart cities or e-healthcare applications. Among other challenges, these networks cover the deployment and interaction of small devices with constrained capabilities and Internet protocol (IP)-based networking connectivity. These constrained devices usually require connection to the Internet to exchange information (e.g., management or sensing data) or access network services. However, only authenticated and authorized devices can, in general, establish this connection. The so-called authentication, authorization and accounting (AAA) services are in charge of performing these tasks on the Internet. Thus, it is necessary to deploy protocols that allow constrained devices to verify their credentials against AAA infrastructures. The Protocol for Carrying Authentication for Network Access (PANA) has been standardized by the Internet engineering task force (IETF) to carry the Extensible Authentication Protocol (EAP), which provides flexible authentication upon the presence of AAA. To the best of our knowledge, this paper is the first deep study of the feasibility of EAP/PANA for network access control in constrained devices. We provide light-weight versions and implementations of these protocols to fit them into constrained devices. These versions have been designed to reduce the impact in standard specifications. The goal of this work is two-fold: (1) to demonstrate the feasibility of EAP/PANA in IoT devices; (2) to provide the scientific community with the first light-weight interoperable implementation of EAP/PANA for constrained devices in the Contiki operating system (Contiki OS), called PANATIKI. The paper also shows a testbed, simulations and experimental results obtained from real and simulated constrained devices.

  19. Highly Reliable PON Optical Splitters for Optical Access Networks in Outside Environments

    Science.gov (United States)

    Watanabe, Hiroshi; Araki, Noriyuki; Fujimoto, Hisashi

    Broadband optical access services are spreading throughout the world, and the number of fiber to the home (FTTH) subscribers is increasing rapidly. Telecom operators are constructing passive optical networks (PONs) to provide optical access services. Externally installed optical splitters for PONs are very important passive devices in optical access networks, and they must provide satisfactory performance as outdoor plant over long periods. Therefore, we calculate the failure rate of optical access networks and assign a failure rate to the optical splitters in optical access networks. The maximum cumulative failure rate of 1 × 8 optical splitters was calculated as 0.025 for an optical access fiber length of 2.1km and a 20-year operating lifetime. We examined planar lightwave circuit (PLC) type optical splitters for use as outside plant in terms of their optical characteristics and environmental reliability. We confirmed that PLC type optical splitters have sufficient optical performance for a PON splitter and sufficient reliability as outside plant in accordance with ITU-T standard values. We estimated the lifetimes of three kinds of PLC type optical splitters by using accelerated aging tests. The estimated failure rate of these splitters installed in optical access networks was below the target value for the cumulative failure rate, and we confirmed that they have sufficient reliability to maintain the quality of the network service. We developed 1 × 8 optical splitter modules with plug and socket type optical connectors and optical fiber cords for optical aerial closures designed for use as outside plant. These technologies make it easy to install optical splitters in an aerial optical closure. The optical splitter modules have sufficient optical performance levels for PONs because the insertion loss at the commercially used wavelengths of 1.31 and 1.55µm is less than the criterion established by ITU-T Recommendation G.671 for optical splitters. We performed a

  20. Performance Analysis of DPSK-OCDMA System for Optical Access Network

    Science.gov (United States)

    Islam, Monirul; Ahmed, N.; Aljunid, S. A.; Ali, Sharafat; Sayeed, S.; Sabri, Naseer

    2016-03-01

    In this research, the performance of optical code division multiple access (OCDMA) using differential phase shift keying (DPSK) has been compared with OCDMA On-Off Keying (OOK). This comparison took place in terms of bit error rate (BER) and receiver power where two bit rates (155 Mbps and 622 Mbps) have been used for this analysis. Using of OptiSystem 7.0 simulation, comparing eye diagram and optical spectrum alongside with BER and Rx power. It is found that OCDMA-DPSK performs better in comparison to OCDMA-OOK. The performance analysis also provides parameter for designing and development of an OCDMA system for optical access network using DPSK.

  1. RNM and CRITER projects: providing access to environmental radioactivity measurements during crisis and in peacetime

    Energy Technology Data Exchange (ETDEWEB)

    Leprieur, F.; Couvez, C.; Manificat, G. [Institut de radioprotection et de surete nucleaire (France)

    2014-07-01

    The multiplicity of actors and sources of information makes it difficult to centralize environmental radioactivity measurements and to provide access to experts and policy makers, but also to the general public. In the event of a radiological accident, many additional measures will also be carried out in the field by those involved in crisis management. In order to answer this problem, two projects were launched by IRSN with the aim of developing tools to centralize information on environmental radioactivity in normal situation (RNM project: National network of radioactive measurements) and during radiological crisis (CRITER project: Crisis and field). The RNM's mission is to contribute to the estimation of doses from ionizing radiation to which people are exposed and to inform the public. In order to achieve this goal, this network collects and makes available to the public the results of measurements of environmental radioactivity obtained in a normal situation by the French stakeholders. More than 18,000 measurements are transmitted each month by all producers to the RNM. After more than 4 years of operation, the database contains nearly 1,200,000 results. The opening in 2010 of the public web site (www.mesure-radioactivite.fr) was also a major step forward toward transparency and information. In case of radiological emergency, IRSN's mission is to centralize and process at the national level, in a database, all the results of measurements or analysis by all stakeholders throughout the crisis, in order to precisely determine the radiological situation of the environment, before, during and after the event. The project CRITER therefore involves the collection of all possible data from all potential sources, transmission, organization, and the publication of the measurements in crisis or post-accident situation. The emergency nature of the situation requires a transmission in near real-time data, facilitated by the development of automatic sensors. For

  2. Access to finance from different finance provider types: Farmer knowledge of the requirements

    OpenAIRE

    Wulandari, Eliana; Meuwissen, Miranda P. M.; Karmana, Maman H.; Oude Lansink, Alfons G. J. M.

    2017-01-01

    Analysing farmer knowledge of the requirements of finance providers can provide valuable insights to policy makers about ways to improve farmers' access to finance. This study compares farmer knowledge of the requirements to obtain finance with the actual requirements set by different finance provider types, and investigates the relation between demographic and socioeconomic factors and farmer knowledge of finance requirements. We use a structured questionnaire to collect data from a sample o...

  3. Nonadditivity of quantum and classical capacities for entanglement breaking multiple-access channels and the butterfly network

    International Nuclear Information System (INIS)

    Grudka, Andrzej; Horodecki, Pawel

    2010-01-01

    We analyze quantum network primitives which are entanglement breaking. We show superadditivity of quantum and classical capacity regions for quantum multiple-access channels and the quantum butterfly network. Since the effects are especially visible at high noise they suggest that quantum information effects may be particularly helpful in the case of the networks with occasional high noise rates. The present effects provide a qualitative borderline between superadditivities of bipartite and multipartite systems.

  4. An Adaptive Time-Spread Multiple-Access Policy for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Konstantinos Oikonomou

    2007-05-01

    Full Text Available Sensor networks require a simple and efficient medium access control policy achieving high system throughput with no or limited control overhead in order to increase the network lifetime by minimizing the energy consumed during transmission attempts. Time-spread multiple-access (TSMA policies that have been proposed for ad hoc network environments, can also be employed in sensor networks, since no control overhead is introduced. However, they do not take advantage of any cross-layer information in order to exploit the idiosyncrasies of the particular sensor network environment such as the presence of typically static nodes and a common destination for the forwarded data. An adaptive probabilistic TSMA-based policy, that is proposed and analyzed in this paper, exploits these idiosyncrasies and achieves higher system throughput than the existing TSMA-based policies without any need for extra control overhead. As it is analytically shown in this paper, the proposed policy always outperforms the existing TSMA-based policies, if certain parameter values are properly set; the analysis also provides for these proper values. It is also shown that the proposed policy is characterized by a certain convergence period and that high system throughput is achieved for long convergence periods. The claims and expectations of the provided analysis are supported by simulation results presented in this paper.

  5. Multirate IP traffic transmission in flexible access networks based on optical FFH-CDMA

    DEFF Research Database (Denmark)

    Raddo, Thiago R.; Sanches, Anderson L.; Tafur Monroy, Idelfonso

    2016-01-01

    In this paper, we propose a new IP transmission architecture over optical fast frequency hopping code-division multiple-access (OFFH-CDMA) network capable of supporting multirate transmissions for applications in flexible optical access networks. The proposed network architecture is independent...

  6. Healthcare provider education: from institutional boxes to dynamic networks.

    Science.gov (United States)

    Eisler, George

    2009-01-01

    The world recognizes the need for close collaboration in planning between the healthcare system and the post-secondary education system; this has also been advocated in the lead article. Forums and mechanisms to facilitate this collaboration are being implemented from local to global environments. Beyond the focus on competency gaps, there are important functional co-dependencies between healthcare and post-secondary education, including the need for a more formalized continuous quality improvement approach at the inter-organizational system level. The case for this close and continuous collaborative relationship is based on the following: (1) a close functional relationship, (2) joint responsibility for healthcare provider education, (3) the urgent need to address the workforce and education strategies for almost all healthcare services areas and (4) the factors that characterize successful and sustained quality improvement in complex adaptive systems. A go-forward vision consisting of an integrated web of academic health networks is proposed, each with its particular shared vision and aligned with an overall vision for healthcare in each provincial jurisdiction, as well as with national and global healthcare objectives.

  7. The changing face of government information providing access in the twenty-first century

    CERN Document Server

    Kumar, Suhasini L

    2006-01-01

    Learn what innovative changes lie in the future of government information The Changing Face of Government Information comprehensively examines the way government documents' librarians acquire, provide access, and provide reference services in the new electronic environment. Noted experts discuss the impact electronic materials have had on the Government Printing Office (GPO), the reference services within the Federal Depository Library Program (FDLP), and the new opportunities in the transition from paper-based information policy to an electronic e-government. This source reveals the latest changes in the field of government documents librarianship and the knowledge and expertise needed to teach users how to access what they need from this enormous wealth of government information. Major changes have taken place in the way government information is created, disseminated, accessed, and preserved. The Changing Face of Government Information explains in detail the tremendous change taking place in libraries and ...

  8. Providing Access and Visualization to Global Cloud Properties from GEO Satellites

    Science.gov (United States)

    Chee, T.; Nguyen, L.; Minnis, P.; Spangenberg, D.; Palikonda, R.; Ayers, J. K.

    2015-12-01

    Providing public access to cloud macro and microphysical properties is a key concern for the NASA Langley Research Center Cloud and Radiation Group. This work describes a tool and method that allows end users to easily browse and access cloud information that is otherwise difficult to acquire and manipulate. The core of the tool is an application-programming interface that is made available to the public. One goal of the tool is to provide a demonstration to end users so that they can use the dynamically generated imagery as an input into their own work flows for both image generation and cloud product requisition. This project builds upon NASA Langley Cloud and Radiation Group's experience with making real-time and historical satellite cloud product imagery accessible and easily searchable. As we see the increasing use of virtual supply chains that provide additional value at each link there is value in making satellite derived cloud product information available through a simple access method as well as allowing users to browse and view that imagery as they need rather than in a manner most convenient for the data provider. Using the Open Geospatial Consortium's Web Processing Service as our access method, we describe a system that uses a hybrid local and cloud based parallel processing system that can return both satellite imagery and cloud product imagery as well as the binary data used to generate them in multiple formats. The images and cloud products are sourced from multiple satellites and also "merged" datasets created by temporally and spatially matching satellite sensors. Finally, the tool and API allow users to access information that spans the time ranges that our group has information available. In the case of satellite imagery, the temporal range can span the entire lifetime of the sensor.

  9. Hand Society and Matching Program Web Sites Provide Poor Access to Information Regarding Hand Surgery Fellowship.

    Science.gov (United States)

    Hinds, Richard M; Klifto, Christopher S; Naik, Amish A; Sapienza, Anthony; Capo, John T

    2016-08-01

    The Internet is a common resource for applicants of hand surgery fellowships, however, the quality and accessibility of fellowship online information is unknown. The objectives of this study were to evaluate the accessibility of hand surgery fellowship Web sites and to assess the quality of information provided via program Web sites. Hand fellowship Web site accessibility was evaluated by reviewing the American Society for Surgery of the Hand (ASSH) on November 16, 2014 and the National Resident Matching Program (NRMP) fellowship directories on February 12, 2015, and performing an independent Google search on November 25, 2014. Accessible Web sites were then assessed for quality of the presented information. A total of 81 programs were identified with the ASSH directory featuring direct links to 32% of program Web sites and the NRMP directory directly linking to 0%. A Google search yielded direct links to 86% of program Web sites. The quality of presented information varied greatly among the 72 accessible Web sites. Program description (100%), fellowship application requirements (97%), program contact email address (85%), and research requirements (75%) were the most commonly presented components of fellowship information. Hand fellowship program Web sites can be accessed from the ASSH directory and, to a lesser extent, the NRMP directory. However, a Google search is the most reliable method to access online fellowship information. Of assessable programs, all featured a program description though the quality of the remaining information was variable. Hand surgery fellowship applicants may face some difficulties when attempting to gather program information online. Future efforts should focus on improving the accessibility and content quality on hand surgery fellowship program Web sites.

  10. Barriers to accessing ATLS provider course for junior doctors at a ...

    African Journals Online (AJOL)

    Barriers to accessing ATLS provider course for junior doctors at a major university hospital in South Africa. ... South African Journal of Surgery ... Subgroup analysis comparing the reasons for PGY1s vs PGY2s demonstrated that not being able to secure a place on course was more common among PGY2s [19% vs 33%, ...

  11. Do Your School Policies Provide Equal Access to Computers? Are You Sure?

    Science.gov (United States)

    DuBois, Phyllis A.; Schubert, Jane G.

    1986-01-01

    Outlines how school policies can unintentionally perpetuate gender discrimination in student computer use and access. Describes four areas of administrative policies that can cause inequities and provides ways for administrators to counteract these policies. Includes discussion of a program to balance computer use, and an abstract of an article…

  12. 34 CFR 364.37 - What access to records must be provided?

    Science.gov (United States)

    2010-07-01

    ... SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT OF EDUCATION STATE INDEPENDENT LIVING SERVICES... Requirements? § 364.37 What access to records must be provided? For the purpose of conducting audits, examinations, and compliance reviews, the State plan must include satisfactory assurances that all recipients...

  13. Does the edge effect impact on the measure of spatial accessibility to healthcare providers?

    Science.gov (United States)

    Gao, Fei; Kihal, Wahida; Le Meur, Nolwenn; Souris, Marc; Deguen, Séverine

    2017-12-11

    Spatial accessibility indices are increasingly applied when investigating inequalities in health. Although most studies are making mentions of potential errors caused by the edge effect, many acknowledge having neglected to consider this concern by establishing spatial analyses within a finite region, settling for hypothesizing that accessibility to facilities will be under-reported. Our study seeks to assess the effect of edge on the accuracy of defining healthcare provider access by comparing healthcare provider accessibility accounting or not for the edge effect, in a real-world application. This study was carried out in the department of Nord, France. The statistical unit we use is the French census block known as 'IRIS' (Ilot Regroupé pour l'Information Statistique), defined by the National Institute of Statistics and Economic Studies. The geographical accessibility indicator used is the "Index of Spatial Accessibility" (ISA), based on the E2SFCA algorithm. We calculated ISA for the pregnant women population by selecting three types of healthcare providers: general practitioners, gynecologists and midwives. We compared ISA variation when accounting or not edge effect in urban and rural zones. The GIS method was then employed to determine global and local autocorrelation. Lastly, we compared the relationship between socioeconomic distress index and ISA, when accounting or not for the edge effect, to fully evaluate its impact. The results revealed that on average ISA when offer and demand beyond the boundary were included is slightly below ISA when not accounting for the edge effect, and we found that the IRIS value was more likely to deteriorate than improve. Moreover, edge effect impact can vary widely by health provider type. There is greater variability within the rural IRIS group than within the urban IRIS group. We found a positive correlation between socioeconomic distress variables and composite ISA. Spatial analysis results (such as Moran's spatial

  14. Resource allocation in heterogeneous cloud radio access networks: advances and challenges

    KAUST Repository

    Dahrouj, Hayssam

    2015-06-01

    Base station densification is increasingly used by network operators to provide better throughput and coverage performance to mobile subscribers in dense data traffic areas. Such densification is progressively diffusing the move from traditional macrocell base stations toward heterogeneous networks with diverse cell sizes (e.g., microcell, picocell, femotcell) and diverse radio access technologies (e.g., GSM, CDMA), and LTE). The coexistence of the different network entities brings an additional set of challenges, particularly in terms of the provisioning of high-speed communications and the management of wireless interference. Resource sharing between different entities, largely incompatible in conventional systems due to the lack of interconnections, becomes a necessity. By connecting all the base stations from different tiers to a central processor (referred to as the cloud) through wire/wireline backhaul links, the heterogeneous cloud radio access network, H-CRAN, provides an open, simple, controllable, and flexible paradigm for resource allocation. This article discusses challenges and recent developments in H-CRAN design. It proposes promising resource allocation schemes in H-CRAN: coordinated scheduling, hybrid backhauling, and multicloud association. Simulations results show how the proposed strategies provide appreciable performance improvement compared to methods from recent literature. © 2015 IEEE.

  15. Opportunistic Nonorthogonal Packet Scheduling in Fixed Broadband Wireless Access Networks

    Directory of Open Access Journals (Sweden)

    Ahmed Mohamed H

    2006-01-01

    Full Text Available In order to mitigate high cochannel interference resulting from dense channel reuse, the interference management issues are often considered as essential part of scheduling schemes in fixed broadband wireless access (FBWA networks. To that end, a series of literature has been published recently, in which a group of base stations forms an interferer group (downlink transmissions from each base station become dominant interference for the users in other in-group base stations, and the scheduling scheme deployed in the group allows only one base station to transmit at a time. As a result of time orthogonality in transmissions, the dominant cochannel interferers are prevented, and hence the packet error rate can be improved. However, prohibiting concurrent transmissions in these orthogonal schemes introduces throughput penalty as well as higher end-to-end packet delay which might not be desirable for real-time services. In this paper, we utilize opportunistic nonorthogonality among the in-group transmissions whenever possible and propose a novel transmission scheduling scheme for FBWA networks. The proposed scheme, in contrast to the proactive interference avoidance techniques, strives for the improvements in delay and throughput efficiency. To facilitate opportunistic nonorthogonal transmissions in the interferer group, estimation of signal-to-interference-plus-noise ratio (SINR is required at the scheduler. We have observed from simulations that the proposed scheme outperforms the reference orthogonal scheme in terms of spectral efficiency, mean packet delay, and packet dropping rate.

  16. A Global Remote Laboratory Experimentation Network and the Experiment Service Provider Business Model and Plans

    Directory of Open Access Journals (Sweden)

    Tor Ivar Eikaas

    2003-07-01

    Full Text Available This paper presents results from the IST KAII Trial project ReLAX - Remote LAboratory eXperimentation trial (IST 1999-20827, and contributes with a framework for a global remote laboratory experimentation network supported by a new business model. The paper presents this new Experiment Service Provider business model that aims at bringing physical experimentation back into the learning arena, where remotely operable laboratory experiments used in advanced education and training schemes are made available to a global education and training market in industry and academia. The business model is based on an approach where individual experiment owners offer remote access to their high-quality laboratory facilities to users around the world. The usage can be for research, education, on-the-job training etc. The access to these facilities is offered via an independent operating company - the Experiment Service Provider. The Experiment Service Provider offers eCommerce services like booking, access control, invoicing, dispute resolution, quality control, customer evaluation services and a unified Lab Portal.

  17. Trust-Based Access Control Model from Sociological Approach in Dynamic Online Social Network Environment

    Science.gov (United States)

    Kim, Seungjoo

    2014-01-01

    There has been an explosive increase in the population of the OSN (online social network) in recent years. The OSN provides users with many opportunities to communicate among friends and family. Further, it facilitates developing new relationships with previously unknown people having similar beliefs or interests. However, the OSN can expose users to adverse effects such as privacy breaches, the disclosing of uncontrolled material, and the disseminating of false information. Traditional access control models such as MAC, DAC, and RBAC are applied to the OSN to address these problems. However, these models are not suitable for the dynamic OSN environment because user behavior in the OSN is unpredictable and static access control imposes a burden on the users to change the access control rules individually. We propose a dynamic trust-based access control for the OSN to address the problems of the traditional static access control. Moreover, we provide novel criteria to evaluate trust factors such as sociological approach and evaluate a method to calculate the dynamic trust values. The proposed method can monitor negative behavior and modify access permission levels dynamically to prevent the indiscriminate disclosure of information. PMID:25374943

  18. Trust-Based Access Control Model from Sociological Approach in Dynamic Online Social Network Environment

    Directory of Open Access Journals (Sweden)

    Seungsoo Baek

    2014-01-01

    Full Text Available There has been an explosive increase in the population of the OSN (online social network in recent years. The OSN provides users with many opportunities to communicate among friends and family. Further, it facilitates developing new relationships with previously unknown people having similar beliefs or interests. However, the OSN can expose users to adverse effects such as privacy breaches, the disclosing of uncontrolled material, and the disseminating of false information. Traditional access control models such as MAC, DAC, and RBAC are applied to the OSN to address these problems. However, these models are not suitable for the dynamic OSN environment because user behavior in the OSN is unpredictable and static access control imposes a burden on the users to change the access control rules individually. We propose a dynamic trust-based access control for the OSN to address the problems of the traditional static access control. Moreover, we provide novel criteria to evaluate trust factors such as sociological approach and evaluate a method to calculate the dynamic trust values. The proposed method can monitor negative behavior and modify access permission levels dynamically to prevent the indiscriminate disclosure of information.

  19. Cross-Layer Framework for Fine-Grained Channel Access in Next Generation High-Density WiFi Networks

    Institute of Scientific and Technical Information of China (English)

    ZHAO Haitao; ZHANG Shaojie; Emiliano Garcia-Palacios

    2016-01-01

    Densely deployed WiFi networks will play a crucial role in providing the capacity for next generation mobile internet.However,due to increasing interference,overlapped channels in WiFi networks and throughput efficiency degradation,densely deployed WiFi networks is not a guarantee to obtain higher throughput.An emergent challenge is how to efficiently utilize scarce spectrum resources,by matching physical layer resources to traffic demand.In this aspect,access control allocation strategies play a pivotal role but remain too coarse-grained.As a solution,this research proposes a flexible framework for fine-grained channel width adaptation and multi-channel access in WiFi networks.This approach,named SFCA (Subcarrier Fine-grained Channel Access),adopts DOFDM (Discontinuous Orthogonal Frequency Division Multiplexing) at the PHY layer.It allocates the frequency resource with a subcarrier granularity,which facilitates the channel width adaptation for multi-channel access and thus brings more flexibility and higher frequency efficiency.The MAC layer uses a frequencytime domain backoff scheme,which combines the popular time-domain BEB scheme with a frequency-domain backoff to decrease access collision,resulting in higher access probability for the contending nodes.SFCA is compared with FICA (an established access scheme) showing significant outperformance.Finally we present results for next generation 802.11 ac WiFi networks.

  20. The role of a bus network in access to primary health care in Metropolitan Auckland, New Zealand.

    Science.gov (United States)

    Rocha, C M; McGuire, S; Whyman, R; Kruger, E; Tennant, M

    2015-09-01

    Background: This study examined the spatial accessibility of the population of metropolitan Auckland, New Zealand to the bus network, to connect them to primary health providers, in this case doctors (GP) and dentists. Analysis of accessibility by ethnic identity and socio-economic status were also carried out, because of existing health inequalities along these dimensions. The underlying hypothesis was that most people would live within easy reach of primary health providers, or easy bus transport to such providers. An integrated geographic model of bus transport routes and stops, with population and primary health providers (medical. and dental practices) was developed and analysed. Although the network of buses in metropolitan Auckland is substantial and robust it was evident that many people live more than 150 metres from a stop. Improving the access to bus stops, particularly in areas of high primary health care need (doctors and dentists), would certainly be an opportunity to enhance spatial access in a growing metropolitan area.

  1. Health care access and quality for persons with disability: Patient and provider recommendations.

    Science.gov (United States)

    McClintock, Heather F; Kurichi, Jibby E; Barg, Frances K; Krueger, Alice; Colletti, Patrice M; Wearing, Krizia A; Bogner, Hillary R

    2018-07-01

    Significant disparities in health care access and quality persist between persons with disabilities (PWD) and persons without disabilities (PWOD). Little research has examined recommendations of patients and providers to improve health care for PWD. We sought to explore patient and health care provider recommendations to improve health care access and quality for PWD through focus groups in the physical world in a community center and in the virtual world in an online community. In all, 17 PWD, 4 PWOD, and 6 health care providers participated in 1 of 5 focus groups. Focus groups were conducted in the virtual world in Second Life ® with Virtual Ability, an online community, and in the physical world at Agape Community Center in Milwaukee, WI. Focus group data were analyzed using a grounded theory methodology. Themes that emerged in focus groups among PWD and PWOD as well as health care providers to improve health care access and quality for PWD were: promoting advocacy, increasing awareness and knowledge, improving communication, addressing assumptions, as well as modifying and creating policy. Many participants discussed political empowerment and engagement as central to health care reform. Both PWD and PWOD as well as health care providers identified common themes potentially important for improving health care for PWD. Patient and health care provider recommendations highlight a need for modification of current paradigms, practices, and approaches to improve the quality of health care provision for PWD. Participants emphasized the need for greater advocacy and political engagement. Copyright © 2018 Elsevier Inc. All rights reserved.

  2. The ARAC client system: network-based access to ARAC

    International Nuclear Information System (INIS)

    Leach, M J; Sumikawa, D; Webster, C

    1999-01-01

    The ARAC Client System allows users (such as emergency managers and first responders) with commonly available desktop and laptop computers to utilize the central ARAC system over the Internet or any other communications link using Internet protocols. Providing cost-effective fast access to the central ARAC system greatly expands the availability of the ARAC capability. The ARAC Client system consists of (1) local client applications running on the remote user's computer, and (2) ''site servers'' that provide secure access to selected central ARAC system capabilities and run on a scalable number of dedicated workstations residing at the central facility. The remote client applications allow users to describe a real or potential them-bio event, electronically sends this information to the central ARAC system which performs model calculations, and quickly receive and visualize the resulting graphical products. The site servers will support simultaneous access to ARAC capabilities by multiple users. The ARAC Client system is based on object-oriented client/server and distributed computing technologies using CORBA and Java, and consists of a large number of interacting components

  3. The Effect of Information Access Strategy on Power Consumption and Reliability in Wireless Sensor Network

    DEFF Research Database (Denmark)

    Tobgay, Sonam; Olsen, Rasmus Løvenstein; Prasad, Ramjee

    2013-01-01

    This paper examines the effect of different information access strategies on power consumption and information reliability, considering the wireless sensor network as the source of information. Basically, the paper explores three different access strategies, namely; reactive, periodic and hybrid...

  4. Switched-based interference reduction scheme for open-access overlaid cellular networks

    KAUST Repository

    Radaydeh, Redha Mahmoud Mesleh; Alouini, Mohamed-Slim

    2012-01-01

    coordination between access points is infeasible. This paper targets interference management in such overlaid networks. It is assumed that the femtocells employ the open-access strategy to reduce cross-tier interference, and can share resources concurrently

  5. Failure Analysis of Network Based Accessible Pedestrian Signals in Closed-Loop Operation

    Science.gov (United States)

    2011-03-01

    The potential failure modes of a network based accessible pedestrian system were analyzed to determine the limitations and benefits of closed-loop operation. The vulnerabilities of the system are accessed using the industry standard process known as ...

  6. Convergent optical wired and wireless long-reach access network using high spectral-efficient modulation.

    Science.gov (United States)

    Chow, C W; Lin, Y H

    2012-04-09

    To provide broadband services in a single and low cost perform, the convergent optical wired and wireless access network is promising. Here, we propose and demonstrate a convergent optical wired and wireless long-reach access networks based on orthogonal wavelength division multiplexing (WDM). Both the baseband signal and the radio-over-fiber (ROF) signal are multiplexed and de-multiplexed in optical domain, hence it is simple and the operation speed is not limited by the electronic bottleneck caused by the digital signal processing (DSP). Error-free de-multiplexing and down-conversion can be achieved for all the signals after 60 km (long-reach) fiber transmission. The scalability of the system for higher bit-rate (60 GHz) is also simulated and discussed.

  7. Accounting for Energy Cost When Designing Energy-Efficient Wireless Access Networks

    Directory of Open Access Journals (Sweden)

    Greta Vallero

    2018-03-01

    Full Text Available Because of the increase of the data traffic demand, wireless access networks, through which users access telecommunication services, have expanded, in terms of size and of capability and, consequently, in terms of power consumption. Therefore, costs to buy the necessary power for the supply of base stations of those networks is becoming very high, impacting the communication cost. In this study, strategies to reduce the amount of money spent for the purchase of the energy consumed by the base stations are proposed for a network powered by solar panels, energy batteries and the power grid. First, the variability of the energy prices is exploited. It provides a cost reduction of up to 30%, when energy is bought in advance. If a part of the base stations is deactivated when the energy price is higher than a given threshold, a compromise between the energy cost and the user coverage drop is needed. In the simulated scenario, the necessary energy cost can be reduced by more than 40%, preserving the user coverage by greater than 94%. Second, the network is introduced to the energy market: it buys and sells energy from/to the traditional power grid. Finally, costs are reduced by the reduction of power consumption of the network, achieved by using microcell base stations. In the considered scenario, up to a 31% cost reduction is obtained, without the deterioration of the quality of service, but a huge Capex expenditure is required.

  8. Virtual shelves in a digital library: a framework for access to networked information sources.

    Science.gov (United States)

    Patrick, T B; Springer, G K; Mitchell, J A; Sievert, M E

    1995-01-01

    Develop a framework for collections-based access to networked information sources that addresses the problem of location-dependent access to information sources. This framework uses a metaphor of a virtual shelf. A virtual shelf is a general-purpose server that is dedicated to a particular information subject class. The identifier of one of these servers identifies its subject class. Location-independent call numbers are assigned to information sources. Call numbers are based on standard vocabulary codes. The call numbers are first mapped to the location-independent identifiers of virtual shelves. When access to an information resource is required, a location directory provides a second mapping of these location-independent server identifiers to actual network locations. The framework has been implemented in two different systems. One system is based on the Open System Foundation/Distributed Computing Environment and the other is based on the World Wide Web. This framework applies in new ways traditional methods of library classification and cataloging. It is compatible with two traditional styles of selecting information searching and browsing. Traditional methods may be combined with new paradigms of information searching that will be able to take advantage of the special properties of digital information. Cooperation between the library-informational science community and the informatics community can provide a means for a continuing application of the knowledge and techniques of library science to the new problems of networked information sources.

  9. Economic Insights into Providing Access to Improved Groundwater Sources in Remote, Low-Resource Areas

    Science.gov (United States)

    Abramson, A.; Lazarovitch, N.; Adar, E.

    2013-12-01

    Groundwater is often the most or only feasible drinking water source in remote, low-resource areas. Yet the economics of its development have not been systematically outlined. We applied CBARWI (Cost-Benefit Analysis for Remote Water Improvements), a recently developed Decision Support System, to investigate the economic, physical and management factors related to the costs and benefits of non-networked groundwater supply in remote areas. Synthetic profiles of community water services (n = 17,962), defined across 14 parameters' values and ranges relevant to remote areas, were imputed into the decision framework, and the parameter effects on economic outcomes were investigated through regression analysis (Table 1). Several approaches were included for financing the improvements, after Abramson et al, 2011: willingness-to -pay (WTP), -borrow (WTB) and -work (WTW) in community irrigation (';water-for-work'). We found that low-cost groundwater development approaches are almost 7 times more cost-effective than conventional boreholes fitted with handpumps. The costs of electric, submersible borehole pumps are comparable only when providing expanded water supplies, and off-grid communities pay significantly more for such expansions. In our model, new source construction is less cost-effective than improvement of existing wells, but necessary for expanding access to isolated households. The financing approach significantly impacts the feasibility of demand-driven cost recovery; in our investigation, benefit exceeds cost in 16, 32 and 48% of water service configurations financed by WTP, WTB and WTW, respectively. Regressions of total cost (R2 = 0.723) and net benefit under WTW (R2 = 0.829) along with analysis of output distributions indicate that parameters determining the profitability of irrigation are different from those determining costs and other measures of net benefit. These findings suggest that the cost-benefit outcomes associated with groundwater-based water

  10. Coordinated scheduling for the downlink of cloud radio-access networks

    KAUST Repository

    Douik, Ahmed S.; Dahrouj, Hayssam; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2015-01-01

    This paper addresses the coordinated scheduling problem in cloud-enabled networks. Consider the downlink of a cloud-radio access network (CRAN), where the cloud is only responsible for the scheduling policy and the synchronization of the transmit

  11. Voice over LTE via Generic access (Volga) as a possible solution of mobile networks transformation

    OpenAIRE

    Stepaniuk, Oleg

    2010-01-01

    This paper is focused on Voice over LTE via Generic Access Network, which concept is to connect the already existing Mobile Switching Centers to the LTE network via a gateway supporting 2G or 3G voice environment.

  12. Energy efficiency for cloud-radio access networks with imperfect channel state information

    KAUST Repository

    Al-Oquibi, Bayan

    2016-12-24

    The advent of smartphones and tablets over the past several years has resulted in a drastic increase of global carbon footprint, due to the explosive growth of data traffic. Improving energy efficiency (EE) becomes, therefore, a crucial design metric in next generation wireless systems (5G). Cloud radio access network (C-RAN), a promising 5G network architecture, provides an efficient framework for improving the EE performance, by means of coordinating the transmission across the network. This paper considers a C-RAN system formed by several clusters of remote radio heads (RRHs), each serving a predetermined set of mobile users (MUs), and assumes imperfect channel state information (CSI). The network performance becomes therefore a function of the intra-cluster and inter-cluster interference, as well as the channel estimation error. The paper optimizes the transmit power of each RRH in order to maximize the network global EE subject to MU service rate requirements and RRHs maximum power constraints. The paper proposes solving the optimization problem using a heuristic algorithm based on techniques from optimization theory via a two-stage iterative solution. Simulation results show that the proposed power allocation algorithm provides an appreciable performance improvement as compared to the conventional systems with maximum power transmission strategy. They further highlight the convergence of the proposed algorithm for different networks scenarios.

  13. Integration of QoS provisioning in home and access networks

    DEFF Research Database (Denmark)

    Popov, Mikhail; Gavler, A.; Sköldström, P.

    2010-01-01

    Approaches for QoS provisioning using UPnP for home networks and GMPLS for access networks are described. A solution for interworking the UPnP and the GMPLS at the residential gateway is proposed.......Approaches for QoS provisioning using UPnP for home networks and GMPLS for access networks are described. A solution for interworking the UPnP and the GMPLS at the residential gateway is proposed....

  14. Access to water provides economic relief through enhanced relationships in Kenya.

    Science.gov (United States)

    Zolnikov, Tara Rava; Blodgett-Salafia, Elizabeth

    2017-03-01

    Sub-Saharan Africa is comprised of low- and middle-income countries subject to the residual effects of chronic poverty. Poverty contributes to health disparities and social inequities. Public health strategies and solutions seek to remedy the effects of poverty. Providing access to quality water is one priority public health project that alleviates adverse health effects, but may have additional outcomes. Previous research has not thoroughly reviewed the economic relief and relationship changes from implemented water interventions. A qualitative phenomenological approach used 52 semi-structured interviews to understand relationship experiences among primary water gatherers and their families after implemented water interventions in a community. This study took place throughout the historically semi-arid eastern region in Kitui, Kenya, where community members have been beneficiaries of various water interventions. Prior to the water intervention, relationships were strained because of economic hardships. Households experienced economic difficulties in paying for children's school fees, buying bricks for housing structures, having water for house gardens, trees for shade in the compound, crops and providing water for their animals. After receiving access to water, relationships improved, because families were able to discuss and address economic challenges. Additional financial revenue was gained and used to pay for water to make bricks to sell or use on housing structures, expand on house gardens and agricultural crops, build new businesses, purchase water for animals, and construct local water spouts near the household. Access to water improved relationships, which encouraged economic growth. This information provides a critical component in understanding the interconnected nature between access to water, poverty and family relationships. Ultimately, this research suggests an increased need for access to quality water worldwide to improve both economic situations

  15. Access to finance from different finance provider types: Farmer knowledge of the requirements.

    Science.gov (United States)

    Wulandari, Eliana; Meuwissen, Miranda P M; Karmana, Maman H; Oude Lansink, Alfons G J M

    2017-01-01

    Analysing farmer knowledge of the requirements of finance providers can provide valuable insights to policy makers about ways to improve farmers' access to finance. This study compares farmer knowledge of the requirements to obtain finance with the actual requirements set by different finance provider types, and investigates the relation between demographic and socioeconomic factors and farmer knowledge of finance requirements. We use a structured questionnaire to collect data from a sample of finance providers and farmers in Java Island, Indonesia. We find that the most important requirements to acquire finance vary among different finance provider types. We also find that farmers generally have little knowledge of the requirements, which are important to each type of finance provider. Awareness campaigns are needed to increase farmer knowledge of the diversity of requirements among the finance provider types.

  16. The shipper as the architect of contractual relations in access to natural gas networks

    International Nuclear Information System (INIS)

    Codognet, Marc-Kevin

    2005-01-01

    Transportation and contractual arrangements are in the kernel of the natural gas reform in Europe. Since third party can access to pipelines, those who wish to ship gas between two locations of a gas network have to arrange transportation services. Natural gas transportation is a set of contractual arrangements and has become a complex contracting process. This paper aims at analyzing the typical economic functions of shippers in third-party access regimes in the natural gas industry in a transaction costs approach. Shippers provide and combine intermediation functions in transportation services markets: information management, matching, bundling and transactions guarantees. In this context, the shipper has appeared as a particular market intermediary specialized in transportation arrangements in the new regime of third party access in the natural gas industry. (Author)

  17. A Service-Oriented Approach for Dynamic Chaining of Virtual Network Functions over Multi-Provider Software-Defined Networks

    Directory of Open Access Journals (Sweden)

    Barbara Martini

    2016-06-01

    Full Text Available Emerging technologies such as Software-Defined Networks (SDN and Network Function Virtualization (NFV promise to address cost reduction and flexibility in network operation while enabling innovative network service delivery models. However, operational network service delivery solutions still need to be developed that actually exploit these technologies, especially at the multi-provider level. Indeed, the implementation of network functions as software running over a virtualized infrastructure and provisioned on a service basis let one envisage an ecosystem of network services that are dynamically and flexibly assembled by orchestrating Virtual Network Functions even across different provider domains, thereby coping with changeable user and service requirements and context conditions. In this paper we propose an approach that adopts Service-Oriented Architecture (SOA technology-agnostic architectural guidelines in the design of a solution for orchestrating and dynamically chaining Virtual Network Functions. We discuss how SOA, NFV, and SDN may complement each other in realizing dynamic network function chaining through service composition specification, service selection, service delivery, and placement tasks. Then, we describe the architecture of a SOA-inspired NFV orchestrator, which leverages SDN-based network control capabilities to address an effective delivery of elastic chains of Virtual Network Functions. Preliminary results of prototype implementation and testing activities are also presented. The benefits for Network Service Providers are also described that derive from the adaptive network service provisioning in a multi-provider environment through the orchestration of computing and networking services to provide end users with an enhanced service experience.

  18. The Encyclopedia of Life v2: Providing Global Access to Knowledge About Life on Earth

    Science.gov (United States)

    2014-01-01

    Abstract The Encyclopedia of Life (EOL, http://eol.org) aims to provide unprecedented global access to a broad range of information about life on Earth. It currently contains 3.5 million distinct pages for taxa and provides content for 1.3 million of those pages. The content is primarily contributed by EOL content partners (providers) that have a more limited geographic, taxonomic or topical scope. EOL aggregates these data and automatically integrates them based on associated scientific names and other classification information. EOL also provides interfaces for curation and direct content addition. All materials in EOL are either in the public domain or licensed under a Creative Commons license. In addition to the web interface, EOL is also accessible through an Application Programming Interface. In this paper, we review recent developments added for Version 2 of the web site and subsequent releases through Version 2.2, which have made EOL more engaging, personal, accessible and internationalizable. We outline the core features and technical architecture of the system. We summarize milestones achieved so far by EOL to present results of the current system implementation and establish benchmarks upon which to judge future improvements. We have shown that it is possible to successfully integrate large amounts of descriptive biodiversity data from diverse sources into a robust, standards-based, dynamic, and scalable infrastructure. Increasing global participation and the emergence of EOL-powered applications demonstrate that EOL is becoming a significant resource for anyone interested in biological diversity. PMID:24891832

  19. The design and implementation of access control management system in IHEP network

    International Nuclear Information System (INIS)

    Wang Yanming; An Dehai; Qi Fazhi

    2010-01-01

    In campus network environment of Institute of High Energy Physics, because of the number of Network devices and computers are large scale, ensuring the access validity of network devices and user's computer, and aiming at effective control the exceptional network communication are technological means to achieve network normal running. The access control system of Campus network of institute of High Energy Physics using MySQL database in the behind, and using CGI PHP HTML language to develop the front interface. The System achieves user information management, user computer access control, cutting down the exceptional network communication and alarm function. Increasing the management effective of network, to ensure campus network safety and reliable running. (authors)

  20. Evolving provider payment models and patient access to innovative medical technology.

    Science.gov (United States)

    Long, Genia; Mortimer, Richard; Sanzenbacher, Geoffrey

    2014-12-01

    Abstract Objective: To investigate the evolving use and expected impact of pay-for-performance (P4P) and risk-based provider reimbursement on patient access to innovative medical technology. Structured interviews with leading private payers representing over 110 million commercially-insured lives exploring current and planned use of P4P provider payment models, evidence requirements for technology assessment and new technology coverage, and the evolving relationship between the two topics. Respondents reported rapid increases in the use of P4P and risk-sharing programs, with roughly half of commercial lives affected 3 years ago, just under two-thirds today, and an expected three-quarters in 3 years. All reported well-established systems for evaluating new technology coverage. Five of nine reported becoming more selective in the past 3 years in approving new technologies; four anticipated that in the next 3 years there will be a higher evidence requirement for new technology access. Similarly, four expected it will become more difficult for clinically appropriate but costly technologies to gain coverage. All reported planning to rely more on these types of provider payment incentives to control costs, but didn't see them as a substitute for payer technology reviews and coverage limitations; they each have a role to play. Interviews limited to nine leading payers with models in place; self-reported data. Likely implications include a more uncertain payment environment for providers, and indirectly for innovative medical technology and future investment, greater reliance on quality and financial metrics, and increased evidence requirements for favorable coverage and utilization decisions. Increasing provider financial risk may challenge the traditional technology adoption paradigm, where payers assumed a 'gatekeeping' role and providers a countervailing patient advocacy role with regard to access to new technology. Increased provider financial risk may result in an

  1. Modeling Social Capital as Dynamic Networks to Promote Access to Oral Healthcare.

    Science.gov (United States)

    Wang, Hua; Northridge, Mary E; Kunzel, Carol; Zhang, Qiuyi; Kum, Susan S; Gilbert, Jessica L; Jin, Zhu; Metcalf, Sara S

    2016-01-01

    Social capital, as comprised of human connections in social networks and their associated benefits, is closely related to the health of individuals, communities, and societies at large. For disadvantaged population groups such as older adults and racial/ethnic minorities, social capital may play a particularly critical role in mitigating the negative effects and reinforcing the positive effects on health. In this project, we model social capital as both cause and effect by simulating dynamic networks. Informed in part by a community-based health promotion program, an agent-based model is contextualized in a GIS environment to explore the complexity of social disparities in oral and general health as experienced at the individual, interpersonal, and community scales. This study provides the foundation for future work investigating how health and healthcare accessibility may be influenced by social networks.

  2. Providing India with Internet access anywhere there is electricity - and Canada with commercial opportunity

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2010-07-01

    Access to high-speed Internet service is booming all over the world but the cost of optic cable installation and other related broadband delivery technology is still too high for many developing countries to afford. A Canada-India R & D group is working on a broadband technology delivered over the power line in order to provide internet access wherever there is electricity. Moreover, the application of such a technology in rural India could also improve the distribution and management of India's national electrical grid, as the risk of electricity theft can be monitored by power assumption tracking. Since the required infrastructure is already in place across the country, this project could be deployed rapidly and in a cost-efficient manner, providing thousands of potential opportunities for rural dwellers as well as for Indian and international companies.

  3. Cognitive Self-Scheduled Mechanism for Access Control in Noisy Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Mario Manzano

    2015-01-01

    Full Text Available Within the challenging environment of intelligent transportation systems (ITS, networked control systems such as platooning guidance of autonomous vehicles require innovative mechanisms to provide real-time communications. Although several proposals are currently under discussion, the design of a rapid, efficient, flexible, and reliable medium access control mechanism which meets the specific constraints of such real-time communications applications remains unsolved in this highly dynamic environment. However, cognitive radio (CR combines the capacity to sense the radio spectrum with the flexibility to adapt to transmission parameters in order to maximize system performance and has thus become an effective approach for the design of dynamic spectrum access (DSA mechanisms. This paper presents the enhanced noncooperative cognitive division multiple access (ENCCMA proposal combining time division multiple access (TDMA and frequency division multiple access (FDMA schemes with CR techniques to obtain a mechanism fulfilling the requirements of real-time communications. The analysis presented here considers the IEEE WAVE and 802.11p as reference standards; however, the proposed medium access control (MAC mechanism can be adapted to operate on the physical layer of different standards. The mechanism also offers the advantage of avoiding signaling, thus enhancing system autonomy as well as behavior in adverse scenarios.

  4. Delay-aware adaptive sleep mechanism for green wireless-optical broadband access networks

    Science.gov (United States)

    Wang, Ruyan; Liang, Alei; Wu, Dapeng; Wu, Dalei

    2017-07-01

    Wireless-Optical Broadband Access Network (WOBAN) is capacity-high, reliable, flexible, and ubiquitous, as it takes full advantage of the merits from both optical communication and wireless communication technologies. Similar to other access networks, the high energy consumption poses a great challenge for building up WOBANs. To shot this problem, we can make some load-light Optical Network Units (ONUs) sleep to reduce the energy consumption. Such operation, however, causes the increased packet delay. Jointly considering the energy consumption and transmission delay, we propose a delay-aware adaptive sleep mechanism. Specifically, we develop a new analytical method to evaluate the transmission delay and queuing delay over the optical part, instead of adopting M/M/1 queuing model. Meanwhile, we also analyze the access delay and queuing delay of the wireless part. Based on such developed delay models, we mathematically derive ONU's optimal sleep time. In addition, we provide numerous simulation results to show the effectiveness of the proposed mechanism.

  5. Distributed Robust Power Minimization for the Downlink of Multi-Cloud Radio Access Networks

    KAUST Repository

    Dhifallah, Oussama Najeeb

    2017-02-07

    Conventional cloud radio access networks assume single cloud processing and treat inter-cloud interference as background noise. This paper considers the downlink of a multi-cloud radio access network (CRAN) where each cloud is connected to several base-stations (BS) through limited-capacity wireline backhaul links. The set of BSs connected to each cloud, called cluster, serves a set of pre-known mobile users (MUs). The performance of the system becomes therefore a function of both inter-cloud and intra-cloud interference, as well as the compression schemes of the limited capacity backhaul links. The paper assumes independent compression scheme and imperfect channel state information (CSI) where the CSI errors belong to an ellipsoidal bounded region. The problem of interest becomes the one of minimizing the network total transmit power subject to BS power and quality of service constraints, as well as backhaul capacity and CSI error constraints. The paper suggests solving the problem using the alternating direction method of multipliers (ADMM). One of the highlight of the paper is that the proposed ADMM-based algorithm can be implemented in a distributed fashion across the multi-cloud network by allowing a limited amount of information exchange between the coupled clouds. Simulation results show that the proposed distributed algorithm provides a similar performance to the centralized algorithm in a reasonable number of iterations.

  6. Evaluation of Persian Professional Web Social Networks\\\\\\' Features, to Provide a Suitable Solution for Optimization of These Networks in Iran

    Directory of Open Access Journals (Sweden)

    Nadjla Hariri

    2013-03-01

    Full Text Available This study aimed to determine the status of Persian professional web social networks' features and provide a suitable solution for optimization of these networks in Iran. The research methods were library research and evaluative method, and study population consisted of 10 Persian professional web social networks. In this study, for data collection, a check list of social networks important tools and features was used. According to the results, “Cloob”, “IR Experts” and “Doreh” were the most compatible networks with the criteria of social networks. Finally, some solutions were presented for optimization of capabilities of Persian professional web social networks.

  7. Revisiting of Channel Access Mechanisms in Mobile Wireless Networks through Exploiting Physical Layer Technologies

    Directory of Open Access Journals (Sweden)

    Junmei Yao

    2018-01-01

    Full Text Available The wireless local area networks (WLANs have been widely deployed with the rapid development of mobile devices and have further been brought into new applications with infrastructure mobility due to the growth of unmanned aerial vehicles (UAVs. However, the WLANs still face persistent challenge on increasing the network throughput to meet the customer’s requirement and fight against the node mobility. Interference is a well-known issue that would degrade the network performance due to the broadcast characteristics of the wireless signals. Moreover, with infrastructure mobility, the interference becomes the key obstacle in pursuing the channel capacity. Legacy interference management mechanism through the channel access control in the MAC layer design of the 802.11 standard has some well-known drawbacks, such as exposed and hidden terminal problems, inefficient rate adaptation, and retransmission schemes, making the efficient interference management an everlasting research topic over the years. Recently, interference management through exploiting physical layer mechanisms has attracted much research interest and has been proven to be a promising way to improve the network throughput, especially under the infrastructure mobility scenarios which provides more indicators for node dynamics. In this paper, we introduce a series of representative physical layer techniques and analyze how they are exploited for interference management to improve the network performance. We also provide some discussions about the research challenges and give potential future research topics in this area.

  8. Quantitative analysis of access strategies to remote information in network services

    DEFF Research Database (Denmark)

    Olsen, Rasmus Løvenstein; Schwefel, Hans-Peter; Hansen, Martin Bøgsted

    2006-01-01

    Remote access to dynamically changing information elements is a required functionality for various network services, including routing and instances of context-sensitive networking. Three fundamentally different strategies for such access are investigated in this paper: (1) a reactive approach in...

  9. Hierarchical micro-mobility management in high-speed multihop access networks

    Institute of Scientific and Technical Information of China (English)

    TANG Bi-hua; MA Xiao-lei; LIU Yuan-an; GAO Jin-chun

    2006-01-01

    This article integrates the hierarchical micro-mobility management and the high-speed multihop access networks (HMAN), to accomplish the smooth handover between different access routers. The proposed soft handover scheme in the high-speed HMAN can solve the micro-mobility management problem in the access network. This article also proposes the hybrid access router (AR) advertisement scheme and AR selection algorithm, which uses the time delay and stable route to the AR as the gateway selection parameters. By simulation, the proposed micro-mobility management scheme can achieve high packet delivery fraction and improve the lifetime of network.

  10. Oceans 2.0 API: Programmatic access to Ocean Networks Canada's sensor data.

    Science.gov (United States)

    Heesemann, M.; Ross, R.; Hoeberechts, M.; Pirenne, B.; MacArthur, M.; Jeffries, M. A.; Morley, M. G.

    2017-12-01

    Ocean Networks Canada (ONC) is a not-for-profit society that operates and manages innovative cabled observatories on behalf of the University of Victoria. These observatories supply continuous power and Internet connectivity to various scientific instruments located in coastal, deep-ocean and Arctic environments. The data from the instruments are relayed to the University of Victoria where they are archived, quality-controlled and made freely available to researchers, educators, and the public. The Oceans 2.0 data management system currently contains over 500 terabytes of data collected over 11 years from thousands of sensors. In order to facilitate access to the data, particularly for large datasets and long-time series of high-resolution data, a project was started in 2016 create a comprehensive Application Programming Interface, the "Oceans 2.0 API," to provide programmatic access to all ONC data products. The development is part of a project entitled "A Research Platform for User-Defined Oceanographic Data Products," funded through CANARIE, a Canadian organization responsible for the design and delivery of digital infrastructure for research, education and innovation [1]. Providing quick and easy access to ONC Data Products from within custom software solutions, allows researchers, modelers and decision makers to focus on what is important: solving their problems, answering their questions and making informed decisions. In this paper, we discuss how to access ONC's vast archive of data programmatically, through the Oceans 2.0 API. In particular we discuss the following: Access to ONC Data Products Access to ONC sensor data in near real-time Programming language support Use Cases References [1] CANARIE. Internet: https://www.canarie.ca/; accessed March 6, 2017.

  11. Variable disparity estimation based intermediate view reconstruction in dynamic flow allocation over EPON-based access networks

    Science.gov (United States)

    Bae, Kyung-Hoon; Lee, Jungjoon; Kim, Eun-Soo

    2008-06-01

    In this paper, a variable disparity estimation (VDE)-based intermediate view reconstruction (IVR) in dynamic flow allocation (DFA) over an Ethernet passive optical network (EPON)-based access network is proposed. In the proposed system, the stereoscopic images are estimated by a variable block-matching algorithm (VBMA), and they are transmitted to the receiver through DFA over EPON. This scheme improves a priority-based access network by converting it to a flow-based access network with a new access mechanism and scheduling algorithm, and then 16-view images are synthesized by the IVR using VDE. Some experimental results indicate that the proposed system improves the peak-signal-to-noise ratio (PSNR) to as high as 4.86 dB and reduces the processing time to 3.52 s. Additionally, the network service provider can provide upper limits of transmission delays by the flow. The modeling and simulation results, including mathematical analyses, from this scheme are also provided.

  12. Access regulation in the next generation access network environment: A comparative study of Hong Kong and Singapore from the transaction cost economics perspectives

    OpenAIRE

    Ho, Au Man

    2012-01-01

    Hong Kong and Singapore have adopted two different models in the regulation of the next generation access (NGA) networks. In Hong Kong, the government has decided that access regulation will not be applied to fibre-based access networks and its strategy will be to rely on facilities-based competition to promote investment in the NGA networks. Singapore, on the other hand, has promoted access/services-based competition over a next generation broadband infrastructure subsidised by public fundin...

  13. Providing comprehensive and consistent access to astronomical observatory archive data: the NASA archive model

    Science.gov (United States)

    McGlynn, Thomas; Fabbiano, Giuseppina; Accomazzi, Alberto; Smale, Alan; White, Richard L.; Donaldson, Thomas; Aloisi, Alessandra; Dower, Theresa; Mazzerella, Joseph M.; Ebert, Rick; Pevunova, Olga; Imel, David; Berriman, Graham B.; Teplitz, Harry I.; Groom, Steve L.; Desai, Vandana R.; Landry, Walter

    2016-07-01

    Since the turn of the millennium a constant concern of astronomical archives have begun providing data to the public through standardized protocols unifying data from disparate physical sources and wavebands across the electromagnetic spectrum into an astronomical virtual observatory (VO). In October 2014, NASA began support for the NASA Astronomical Virtual Observatories (NAVO) program to coordinate the efforts of NASA astronomy archives in providing data to users through implementation of protocols agreed within the International Virtual Observatory Alliance (IVOA). A major goal of the NAVO collaboration has been to step back from a piecemeal implementation of IVOA standards and define what the appropriate presence for the US and NASA astronomy archives in the VO should be. This includes evaluating what optional capabilities in the standards need to be supported, the specific versions of standards that should be used, and returning feedback to the IVOA, to support modifications as needed. We discuss a standard archive model developed by the NAVO for data archive presence in the virtual observatory built upon a consistent framework of standards defined by the IVOA. Our standard model provides for discovery of resources through the VO registries, access to observation and object data, downloads of image and spectral data and general access to archival datasets. It defines specific protocol versions, minimum capabilities, and all dependencies. The model will evolve as the capabilities of the virtual observatory and needs of the community change.

  14. Stochastic geometry model for multi-channel fog radio access networks

    KAUST Repository

    Emara, Mostafa; Elsawy, Hesham; Sorour, Sameh; Al-Ghadhban, Samir; Alouini, Mohamed-Slim; Al-Naffouri, Tareq Y.

    2017-01-01

    Cache-enabled base station (BS) densification, denoted as a fog radio access network (F-RAN), is foreseen as a key component of 5G cellular networks. F-RAN enables storing popular files at the network edge (i.e., BS caches), which empowers local

  15. Design Aspects of An Energy-Efficient, Lightweight Medium Access Control Protocol for Wireless Sensor Networks

    NARCIS (Netherlands)

    van Hoesel, L.F.W.; Havinga, Paul J.M.

    2006-01-01

    This document gives an overview of the most relevant design aspects of the lightweight medium access control (LMAC) protocol [16] for wireless sensor networks (WSNs). These aspects include selfconfiguring and localized operation of the protocol, time synchronization in multi-hop networks, network

  16. Self-management for unified heterogeneous radio access networks

    NARCIS (Netherlands)

    Litjens, R.; Gunnarsson, F.; Sayrac, B.; Spaey, K.; Willcock, C.; Eisenblätter, A.; Rodríguez, B.G.; Kürner, T.

    2013-01-01

    The development of self-management solutions for (multi-technology, multi-layer) mobile communication networks is driven by their increasing operational complexity. Initial stand-alone SON (Self-Organizing Networks) solutions are already available, but are not sufficient to handle the networks of

  17. Local empathy provides global minimization of congestion in communication networks

    Science.gov (United States)

    Meloni, Sandro; Gómez-Gardeñes, Jesús

    2010-11-01

    We present a mechanism to avoid congestion in complex networks based on a local knowledge of traffic conditions and the ability of routers to self-coordinate their dynamical behavior. In particular, routers make use of local information about traffic conditions to either reject or accept information packets from their neighbors. We show that when nodes are only aware of their own congestion state they self-organize into a hierarchical configuration that delays remarkably the onset of congestion although leading to a sharp first-order-like congestion transition. We also consider the case when nodes are aware of the congestion state of their neighbors. In this case, we show that empathy between nodes is strongly beneficial to the overall performance of the system and it is possible to achieve larger values for the critical load together with a smooth, second-order-like, transition. Finally, we show how local empathy minimize the impact of congestion as much as global minimization. Therefore, here we present an outstanding example of how local dynamical rules can optimize the system’s functioning up to the levels reached using global knowledge.

  18. Medium access control and network layer design for 60 GHz wireless personal area networks

    NARCIS (Netherlands)

    An, X.

    2010-01-01

    The unlicensed frequency band around 60 GHz is a very promising spectrum due to its potential to provide multiple gigabits per second based data rates for short range wireless communication. Hence, 60 GHz radio is an attractive candidate to enable ultra high rate Wireless Personal Area Networks

  19. Principals' Perceptions of Social Networking Access, Its Relationship to Cyberbullying, the Importance of Student Achievement, and the School Environment

    Science.gov (United States)

    Townsel, Andrae

    2015-01-01

    The purpose of this study was to examine the principals' perceptions of social networking access and its relationship to cyberbullying, the importance of student achievement, and the school environment across the United States. This research provides some evidence on how principals perceive and understand the threat of cyberbullying and its…

  20. Medium Access Control Protocols for Cognitive Radio Ad Hoc Networks: A Survey

    Directory of Open Access Journals (Sweden)

    Mahdi Zareei

    2017-09-01

    Full Text Available New wireless network paradigms will demand higher spectrum use and availability to cope with emerging data-hungry devices. Traditional static spectrum allocation policies cause spectrum scarcity, and new paradigms such as Cognitive Radio (CR and new protocols and techniques need to be developed in order to have efficient spectrum usage. Medium Access Control (MAC protocols are accountable for recognizing free spectrum, scheduling available resources and coordinating the coexistence of heterogeneous systems and users. This paper provides an ample review of the state-of-the-art MAC protocols, which mainly focuses on Cognitive Radio Ad Hoc Networks (CRAHN. First, a description of the cognitive radio fundamental functions is presented. Next, MAC protocols are divided into three groups, which are based on their channel access mechanism, namely time-slotted protocol, random access protocol and hybrid protocol. In each group, a detailed and comprehensive explanation of the latest MAC protocols is presented, as well as the pros and cons of each protocol. A discussion on future challenges for CRAHN MAC protocols is included with a comparison of the protocols from a functional perspective.

  1. Allocation of spectral and spatial modes in multidimensional metro-access optical networks

    Science.gov (United States)

    Gao, Wenbo; Cvijetic, Milorad

    2018-04-01

    Introduction of spatial division multiplexing (SDM) has added a new dimension in an effort to increase optical fiber channel capacity. At the same time, it can also be explored as an advanced optical networking tool. In this paper, we have investigated the resource allocation to end-users in multidimensional networking structure with plurality of spectral and spatial modes actively deployed in different networking segments. This presents a more comprehensive method as compared to the common practice where the segments of optical network are analyzed independently since the interaction between network hierarchies is included into consideration. We explored the possible transparency from the metro/core network to the optical access network, analyzed the potential bottlenecks from the network architecture perspective, and identified an optimized network structure. In our considerations, the viability of optical grooming through the entire hierarchical all-optical network is investigated by evaluating the effective utilization and spectral efficiency of the network architecture.

  2. Impact of Users Identities and Access Conditions on Downlink Performance in Closed Small-Cell Networks

    KAUST Repository

    Radaydeh, Redha

    2015-05-26

    This paper investigates the effect of various operation parameters on the downlink user performance in overlaid small-cell networks. The case study considers closed-access small cells (e.g., femtocells), wherein only active authorized user equipments (UEs) can be served, and each of which is allocated single downlink channel at a time. On the other hand, the macrocell base station can unconditionally serve macrocell UEs that exist inside its coverage space. The available channels can be shared simultaneously in the macrocell network and the femtocell network. Moreover, a channel can be reused only at the macrocell base station. The analysis provides quantitative approaches to model UEs identities, their likelihoods of being active, and their likelihoods of producing interference, considering UEs classifications, locations, and access capabilities. Moreover, it develops models for various interference sources observed from effective interference femtocells, considering femtocells capacities and operation conditions. The associated formulations to describe a desired UE performance and the impact of the number of available channels as well as the adopted channel assignment approach are thoroughly investigated. The results are generally presented for any channel models of interference sources as well as the desired source of the served UE. Moreover, specific channel models are then adopted, for which generalized closedform analytical results for the desired UE outage probability performance are obtained. Numerical and simulation results are presented to further clarify the main outcomes of the developed analysis.

  3. Enabling Broadband as Commodity within Access Networks: A QoS Recipe

    Science.gov (United States)

    Areizaga, Enrique; Foglar, Andreas; Elizondo, Antonio J.; Geilhardt, Frank

    This paper describes the QoS features that will transform the access networks landscape in order to bring “Broadband” as a commodity while setting up the pillars of the “Future Media Internet”. Quality of Experience is obviously key for emerging and future services. Broadcasting services will first need to equal the QoE of their counterparts in the Open-air market (for IP-TV examples would be artifact-free, no picture freezing, fast zapping times) and offer new features often using interactivity (Time-shifted TV, access to more content, 3DTV with feeling of presence). The huge variety of communications alternatives will lead to different requirements per customer, whose needs will also be dependent on parameters like where the connection is made, the time of the day/day of the week/period of the year or even his/her mood. Today’s networks, designed for providing just Broadband connectivity, will not be enough to satisfy customer’s needs and will necessarily support the introduction of new and innovative services. The Networks of the future should learn from the way the users are communicating, what services they are using, where, when, and how, and adapt accordingly.

  4. Secure wide area network access to CMS analysis data using the Lustre filesystem

    International Nuclear Information System (INIS)

    Bourilkov, D; Avery, P; Cheng, M; Fu, Y; Kim, B; Palencia, J; Budden, R; Benninger, K; Rodriquez, J L; Dilascio, J; Dykstra, D; Seenu, N

    2012-01-01

    This paper reports the design and implementation of a secure, wide area network (WAN), distributed filesystem by the ExTENCI project (Extending Science Through Enhanced National CyberInfrastructure), based on the Lustre filesystem. The system is used for remote access to analysis data from the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC), and from the Lattice Quantum ChromoDynamics (LQCD) project. Security is provided by Kerberos authentication and authorization with additional fine grained control based on Lustre ACLs (Access Control List) and quotas. We investigate the impact of using various Kerberos security flavors on the I/O rates of CMS applications on client nodes reading and writing data to the Lustre filesystem, and on LQCD benchmarks. The clients can be real or virtual nodes. We are investigating additional options for user authentication based on user certificates.

  5. Secure wide area network access to CMS analysis data using the Lustre filesystem

    Science.gov (United States)

    Bourilkov, D.; Avery, P.; Cheng, M.; Fu, Y.; Kim, B.; Palencia, J.; Budden, R.; Benninger, K.; Rodriquez, J. L.; Dilascio, J.; Dykstra, D.; Seenu, N.

    2012-12-01

    This paper reports the design and implementation of a secure, wide area network (WAN), distributed filesystem by the ExTENCI project (Extending Science Through Enhanced National CyberInfrastructure), based on the Lustre filesystem. The system is used for remote access to analysis data from the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC), and from the Lattice Quantum ChromoDynamics (LQCD) project. Security is provided by Kerberos authentication and authorization with additional fine grained control based on Lustre ACLs (Access Control List) and quotas. We investigate the impact of using various Kerberos security flavors on the I/O rates of CMS applications on client nodes reading and writing data to the Lustre filesystem, and on LQCD benchmarks. The clients can be real or virtual nodes. We are investigating additional options for user authentication based on user certificates.

  6. Hierarchy Bayesian model based services awareness of high-speed optical access networks

    Science.gov (United States)

    Bai, Hui-feng

    2018-03-01

    As the speed of optical access networks soars with ever increasing multiple services, the service-supporting ability of optical access networks suffers greatly from the shortage of service awareness. Aiming to solve this problem, a hierarchy Bayesian model based services awareness mechanism is proposed for high-speed optical access networks. This approach builds a so-called hierarchy Bayesian model, according to the structure of typical optical access networks. Moreover, the proposed scheme is able to conduct simple services awareness operation in each optical network unit (ONU) and to perform complex services awareness from the whole view of system in optical line terminal (OLT). Simulation results show that the proposed scheme is able to achieve better quality of services (QoS), in terms of packet loss rate and time delay.

  7. Digital Signal Processing for a Sliceable Transceiver for Optical Access Networks

    DEFF Research Database (Denmark)

    Saldaña Cercos, Silvia; Wagner, Christoph; Vegas Olmos, Juan José

    2015-01-01

    Methods to upgrade the network infrastructure to cope with current traffic demands has attracted increasing research efforts. A promising alternative is signal slicing. Signal slicing aims at re-using low bandwidth equipment to satisfy high bandwidth traffic demands. This technique has been used...... also for implementing full signal path symmetry in real-time oscilloscopes to provide performance and signal fidelity (i.e. lower noise and jitter). In this paper the key digital signal processing (DSP) subsystems required to achieve signal slicing are surveyed. It also presents, for the first time...... penalty is reported for 10 Gbps. Power savings of the order of hundreds of Watts can be obtained when using signal slicing as an alternative to 10 Gbps implemented access networks....

  8. College students' preferences for health care providers when accessing sexual health resources.

    Science.gov (United States)

    Garcia, Carolyn M; Lechner, Kate E; Frerich, Ellen A; Lust, Katherine A; Eisenberg, Marla E

    2014-01-01

    Many emerging adults (18-25 year olds) report unmet health needs and disproportionately experience problems such as sexually transmitted infections. This study was conducted to examine college students' perceptions of health care providers, specifically in the context of accessing sexual health resources. Students (N = 52) were recruited from five diverse colleges in one state to participate in a one-to-one interview that involved walking and virtually exploring resources on and near campus. Interviews were conducted from May to November 2010. Open-ended one-to-one interview questions. Inductive qualitative analysis yielded six themes summarizing students' perceptions of provider characteristics, health care resources, the role of their peers, and students' suggestions for strengthening health care services. Importantly, students consider a variety of staff-and their student peers-to be resources for sexual health information and services. Findings emphasize the importance of collaboration between health service staff and broader campus staff because students often turn to campus staff initially. Postsecondary students welcome opportunities to know a provider through interactive websites that include details about providers on campus; their decisions to seek sexual health care services are influenced by their perceptions of providers' characteristics and interpersonal skills. © 2014 Wiley Periodicals, Inc.

  9. Security of social network credentials for accessing course portal: Users' experience

    Science.gov (United States)

    Katuk, Norliza; Fong, Choo Sok; Chun, Koo Lee

    2015-12-01

    Social login (SL) has recently emerged as a solution for single sign-on (SSO) within the web and mobile environments. It allows users to use their existing social network credentials (SNC) to login to third party web applications without the need to create a new identity in the intended applications' database. Although it has been used by many web application providers, its' applicability in accessing learning materials is not yet fully investigated. Hence, this research aims to explore users' (i.e., instructors' and students') perception and experience on the security of SL for accessing learning contents. A course portal was developed for students at a higher learning institution and it provides two types of user authentications (i) traditional user authentication, and (ii) SL facility. Users comprised instructors and students evaluated the login facility of the course portal through a controlled lab experimental study following the within-subject design. The participants provided their feedback in terms of the security of SL for accessing learning contents. The study revealed that users preferred to use SL over the traditional authentication, however, they concerned on the security of SL and their privacy.

  10. The DEDUCE Guided Query tool: providing simplified access to clinical data for research and quality improvement.

    Science.gov (United States)

    Horvath, Monica M; Winfield, Stephanie; Evans, Steve; Slopek, Steve; Shang, Howard; Ferranti, Jeffrey

    2011-04-01

    In many healthcare organizations, comparative effectiveness research and quality improvement (QI) investigations are hampered by a lack of access to data created as a byproduct of patient care. Data collection often hinges upon either manual chart review or ad hoc requests to technical experts who support legacy clinical systems. In order to facilitate this needed capacity for data exploration at our institution (Duke University Health System), we have designed and deployed a robust Web application for cohort identification and data extraction--the Duke Enterprise Data Unified Content Explorer (DEDUCE). DEDUCE is envisioned as a simple, web-based environment that allows investigators access to administrative, financial, and clinical information generated during patient care. By using business intelligence tools to create a view into Duke Medicine's enterprise data warehouse, DEDUCE provides a Guided Query functionality using a wizard-like interface that lets users filter through millions of clinical records, explore aggregate reports, and, export extracts. Researchers and QI specialists can obtain detailed patient- and observation-level extracts without needing to understand structured query language or the underlying database model. Developers designing such tools must devote sufficient training and develop application safeguards to ensure that patient-centered clinical researchers understand when observation-level extracts should be used. This may mitigate the risk of data being misunderstood and consequently used in an improper fashion. Copyright © 2010 Elsevier Inc. All rights reserved.

  11. Providing Access to Census-based Interaction Data in the UK: That's WICID!

    Directory of Open Access Journals (Sweden)

    John Stillwell

    2006-08-01

    Full Text Available The Census Interaction Data Service (CIDS is funded by the Economic and Social Research Council in the UK to provide access for social science researchers and students to the detailed migration and journey-to-work statistics that are collected by the national statistical agencies. These interaction data sets are known collectively as the Special Migration Statistics (SMS and the Special Workplace Statistics (SWS. This paper outlines how problems of user access to these data have been tackled through the development of a web-based system known as WICID (Web-based Interface to Census Interaction Data. The paper illustrates various interface features including some of the query building facilities that enable users to extract counts of flows of particular groups of individuals between selected origin and destination areas. New tools are outlined for assisting area selection using digital maps of census geographies, for planning output and for adding value to the data through analysis. Mapping of flows of migrants between London boroughs and the rest of the UK demonstrates the value of the data. The paper begins with a summary of the data sets that are contained within the system and an outline of the system architecture.

  12. Providing interoperability of eHealth communities through peer-to-peer networks.

    Science.gov (United States)

    Kilic, Ozgur; Dogac, Asuman; Eichelberg, Marco

    2010-05-01

    Providing an interoperability infrastructure for Electronic Healthcare Records (EHRs) is on the agenda of many national and regional eHealth initiatives. Two important integration profiles have been specified for this purpose, namely, the "Integrating the Healthcare Enterprise (IHE) Cross-enterprise Document Sharing (XDS)" and the "IHE Cross Community Access (XCA)." IHE XDS describes how to share EHRs in a community of healthcare enterprises and IHE XCA describes how EHRs are shared across communities. However, the current version of the IHE XCA integration profile does not address some of the important challenges of cross-community exchange environments. The first challenge is scalability. If every community that joins the network needs to connect to every other community, i.e., a pure peer-to-peer network, this solution will not scale. Furthermore, each community may use a different coding vocabulary for the same metadata attribute, in which case, the target community cannot interpret the query involving such an attribute. Yet another important challenge is that each community may (and typically will) have a different patient identifier domain. Querying for the patient identifiers in the target community using patient demographic data may create patient privacy concerns. In this paper, we address each of these challenges and show how they can be handled effectively in a superpeer-based peer-to-peer architecture.

  13. College Students’ Preferences for Health Care Providers when Accessing Sexual Health Resources

    Science.gov (United States)

    Garcia, Carolyn M.; Lechner, Kate E.; Frerich, Ellen A.; Lust, Katherine A.; Eisenberg, Marla E.

    2017-01-01

    Objective Many emerging adults (18–25 year olds) report unmet health needs and disproportionately experience problems such as sexually transmitted infections. This study was conducted to examine college students’ perceptions of health care providers, specifically in the context of accessing sexual health resources. Design and Sample Students (N=52) were recruited from five diverse colleges in one state to participate in a one-to-one interview that involved walking and virtually exploring resources on and near campus. Interviews were conducted from May to November 2010. Results Inductive qualitative analysis yielded six themes summarizing students’ perceptions of provider characteristics, health care resources, the role of their peers, and students’ suggestions for strengthening health care services. Importantly, students consider a variety of staff—and their student peers—to be resources for sexual health information and services. Conclusions Findings emphasize the importance of collaboration between health service staff and broader campus staff because students often turn to campus staff initially. Post-secondary students welcome opportunities to know a provider through interactive websites that include details about providers on campus; their decisions to seek sexual health care services are influenced by their perceptions of providers’ characteristics and interpersonal skills. PMID:25159532

  14. Frontline health workers as brokers: provider perceptions, experiences and mitigating strategies to improve access to essential medicines in South Africa.

    Science.gov (United States)

    Magadzire, Bvudzai Priscilla; Budden, Ashwin; Ward, Kim; Jeffery, Roger; Sanders, David

    2014-11-05

    Front-line health providers have a unique role as brokers (patient advocates) between the health system and patients in ensuring access to medicines (ATM). ATM is a fundamental component of health systems. This paper examines in a South African context supply- and demand- ATM barriers from the provider perspective using a five dimensional framework: availability (fit between existing resources and clients' needs); accessibility (fit between physical location of healthcare and location of clients); accommodation (fit between the organisation of services and clients' practical circumstances); acceptability (fit between clients' and providers' mutual expectations and appropriateness of care) and affordability (fit between cost of care and ability to pay). This cross-sectional, qualitative study uses semi-structured interviews with nurses, pharmacy personnel and doctors. Thirty-six providers were purposively recruited from six public sector Community Health Centres in two districts in the Eastern Cape Province representing both rural and urban settings. Content analysis combined structured coding and grounded theory approaches. Finally, the five dimensional framework was applied to illustrate the interconnected facets of the issue. Factors perceived to affect ATM were identified. Availability of medicines was hampered by logistical bottlenecks in the medicines supply chain; poor public transport networks affected accessibility. Organization of disease programmes meshed poorly with the needs of patients with comorbidities and circular migrants who move between provinces searching for economic opportunities, proximity to services such as social grants and shopping centres influenced where patients obtain medicines. Acceptability was affected by, for example, HIV related stigma leading patients to seek distant services. Travel costs exacerbated by the interplay of several ATM barriers influenced affordability. Providers play a brokerage role by adopting flexible

  15. Caching and Network Coding for Smart Radio Access

    NARCIS (Netherlands)

    Serbetci, Berksan

    2018-01-01

    The current generation has undoubtedly been witnessing a revolution of wireless network technologies in recent decades. First of all, there has been an enormous growth of wireless user equipments and network infrastructures in terms of both number and variety. Moreover, data traffic over wireless

  16. Enhancing Sensing and Channel Access in Cognitive Radio Networks

    KAUST Repository

    Hamza, Doha R.

    2014-01-01

    relaying is employed as an incentive for the primary network. The scheme is shown to outperform a number of reference schemes such as best relay selection. Finally, we consider a network of multiple primary and secondary users. We propose a three

  17. Provably Secure Heterogeneous Access Control Scheme for Wireless Body Area Network.

    Science.gov (United States)

    Omala, Anyembe Andrew; Mbandu, Angolo Shem; Mutiria, Kamenyi Domenic; Jin, Chunhua; Li, Fagen

    2018-04-28

    Wireless body area network (WBAN) provides a medium through which physiological information could be harvested and transmitted to application provider (AP) in real time. Integrating WBAN in a heterogeneous Internet of Things (IoT) ecosystem would enable an AP to monitor patients from anywhere and at anytime. However, the IoT roadmap of interconnected 'Things' is still faced with many challenges. One of the challenges in healthcare is security and privacy of streamed medical data from heterogeneously networked devices. In this paper, we first propose a heterogeneous signcryption scheme where a sender is in a certificateless cryptographic (CLC) environment while a receiver is in identity-based cryptographic (IBC) environment. We then use this scheme to design a heterogeneous access control protocol. Formal security proof for indistinguishability against adaptive chosen ciphertext attack and unforgeability against adaptive chosen message attack in random oracle model is presented. In comparison with some of the existing access control schemes, our scheme has lower computation and communication cost.

  18. An oncofetal glycosaminoglycan modification provides therapeutic access to Cisplatin-resistant bladder cancer

    DEFF Research Database (Denmark)

    Seiler, Roland; Oo, Htoo Zarni; Tortora, Davide

    2017-01-01

    the malaria parasite Plasmodium falciparum, we can target these sugar chains, and our results showed a significant antitumor effect in cisplatin-resistant bladder cancer. This novel treatment paradigm provides therapeutic access to bladder cancers not responding to cisplatin.......BACKGROUND: Although cisplatin-based neoadjuvant chemotherapy (NAC) improves survival of unselected patients with muscle-invasive bladder cancer (MIBC), only a minority responds to therapy and chemoresistance remains a major challenge in this disease setting. OBJECTIVE: To investigate the clinical...... significance of oncofetal chondroitin sulfate (ofCS) glycosaminoglycan chains in cisplatin-resistant MIBC and to evaluate these as targets for second-line therapy. DESIGN, SETTING, AND PARTICIPANTS: An ofCS-binding recombinant VAR2CSA protein derived from the malaria parasite Plasmodium falciparum (rVAR2...

  19. Biological approaches for addressing the grand challenge of providing access to clean drinking water

    Science.gov (United States)

    2011-01-01

    The U.S. National Academy of Engineering (NAE) recently published a document presenting "Grand Challenges for Engineering". This list was proposed by leading engineers and scientists from around the world at the request of the U.S. National Science Foundation (NSF). Fourteen topics were selected for these grand challenges, and at least seven can be addressed using the tools and methods of biological engineering. Here we describe how biological engineers can address the challenge of providing access to clean drinking water. This issue must be addressed in part by removing or inactivating microbial and chemical contaminants in order to properly deliver water safe for human consumption. Despite many advances in technologies this challenge is expanding due to increased pressure on fresh water supplies and to new opportunities for growth of potentially pathogenic organisms. PMID:21453515

  20. Performance Evaluation of Peer-to-Peer Progressive Download in Broadband Access Networks

    Science.gov (United States)

    Shibuya, Megumi; Ogishi, Tomohiko; Yamamoto, Shu

    P2P (Peer-to-Peer) file sharing architectures have scalable and cost-effective features. Hence, the application of P2P architectures to media streaming is attractive and expected to be an alternative to the current video streaming using IP multicast or content delivery systems because the current systems require expensive network infrastructures and large scale centralized cache storage systems. In this paper, we investigate the P2P progressive download enabling Internet video streaming services. We demonstrated the capability of the P2P progressive download in both laboratory test network as well as in the Internet. Through the experiments, we clarified the contribution of the FTTH links to the P2P progressive download in the heterogeneous access networks consisting of FTTH and ADSL links. We analyzed the cause of some download performance degradation occurred in the experiment and discussed about the effective methods to provide the video streaming service using P2P progressive download in the current heterogeneous networks.

  1. Structural equation modelling of determinants of customer satisfaction of mobile network providers: Case of Kolkata, India

    Directory of Open Access Journals (Sweden)

    Shibashish Chakraborty

    2014-12-01

    Full Text Available The Indian market of mobile network providers is growing rapidly. India is the second largest market of mobile network providers in the world and there is intense competition among existing players. In such a competitive market, customer satisfaction becomes a key issue. The objective of this paper is to develop a customer satisfaction model of mobile network providers in Kolkata. The results indicate that generic requirements (an aggregation of output quality and perceived value, flexibility, and price are the determinants of customer satisfaction. This study offers insights for mobile network providers to understand the determinants of customer satisfaction.

  2. A CoAP-Based Network Access Authentication Service for Low-Power Wide Area Networks: LO-CoAP-EAP

    Directory of Open Access Journals (Sweden)

    Dan Garcia-Carrillo

    2017-11-01

    Full Text Available The Internet-of-Things (IoT landscape is expanding with new radio technologies. In addition to the Low-Rate Wireless Personal Area Network (LR-WPAN, the recent set of technologies conforming the so-called Low-Power Wide Area Networks (LP-WAN offers long-range communications, allowing one to send small pieces of information at a reduced energy cost, which promotes the creation of new IoT applications and services. However, LP-WAN technologies pose new challenges since they have strong limitations in the available bandwidth. In general, a first step prior to a smart object being able to gain access to the network is the process of network access authentication. It involves authentication, authorization and key management operations. This process is of vital importance for operators to control network resources. However, proposals for managing network access authentication in LP-WAN are tailored to the specifics of each technology, which could introduce interoperability problems in the future. In this sense, little effort has been put so far into providing a wireless-independent solution for network access authentication in the area of LP-WAN. To fill this gap, we propose a service named Low-Overhead CoAP-EAP (LO-CoAP-EAP, which is based on previous work designed for LR-WPAN. LO-CoAP-EAP integrates the use of Authentication, Authorization and Accounting (AAA infrastructures and the Extensible Authentication Protocol (EAP protocol. For this integration, we use the Constrained Application Protocol (CoAP to design a network authentication service independent of the type of LP-WAN technology. LO-CoAP-EAP represents a trade-off between flexibility, wireless technology independence, scalability and performance in LP-WAN.

  3. A CoAP-Based Network Access Authentication Service for Low-Power Wide Area Networks: LO-CoAP-EAP.

    Science.gov (United States)

    Garcia-Carrillo, Dan; Marin-Lopez, Rafael; Kandasamy, Arunprabhu; Pelov, Alexander

    2017-11-17

    The Internet-of-Things (IoT) landscape is expanding with new radio technologies. In addition to the Low-Rate Wireless Personal Area Network (LR-WPAN), the recent set of technologies conforming the so-called Low-Power Wide Area Networks (LP-WAN) offers long-range communications, allowing one to send small pieces of information at a reduced energy cost, which promotes the creation of new IoT applications and services. However, LP-WAN technologies pose new challenges since they have strong limitations in the available bandwidth. In general, a first step prior to a smart object being able to gain access to the network is the process of network access authentication. It involves authentication, authorization and key management operations. This process is of vital importance for operators to control network resources. However, proposals for managing network access authentication in LP-WAN are tailored to the specifics of each technology, which could introduce interoperability problems in the future. In this sense, little effort has been put so far into providing a wireless-independent solution for network access authentication in the area of LP-WAN. To fill this gap, we propose a service named Low-Overhead CoAP-EAP (LO-CoAP-EAP), which is based on previous work designed for LR-WPAN. LO-CoAP-EAP integrates the use of Authentication, Authorization and Accounting (AAA) infrastructures and the Extensible Authentication Protocol (EAP) protocol. For this integration, we use the Constrained Application Protocol (CoAP) to design a network authentication service independent of the type of LP-WAN technology. LO-CoAP-EAP represents a trade-off between flexibility, wireless technology independence, scalability and performance in LP-WAN.

  4. African Copyright and Access to Knowledge Network (ACA2K ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    ... copyright climate could limit access to knowledge goods and thereby hinder ... Congratulations to the first cohort of Women in Climate Change Science Fellows! ... International Water Resources Association, in close collaboration with IDRC, ...

  5. On the Impact of Closed Access and Users Identities in Spectrum-Shared Overlaid Wireless Networks

    KAUST Repository

    Radaydeh, Redha M.; Gaaloul, Fakhreddine; Alouini, Mohamed-Slim

    2016-01-01

    © 2015 IEEE. This paper develops analytical models to investigate the impact of various operation terms and parameters on the downlink performance of spectrum-shared overlaid networks under closed-access small cells deployment. It is considered

  6. Impact of Users Identities and Access Conditions on Downlink Performance in Closed Small-Cell Networks

    KAUST Repository

    Radaydeh, Redha; Gaaloul, Fakhreddine; Alouini, Mohamed-Slim

    2015-01-01

    This paper investigates the effect of various operation parameters on the downlink user performance in overlaid small-cell networks. The case study considers closed-access small cells (e.g., femtocells), wherein only active authorized user

  7. Low-Complexity Scheduling and Power Adaptation for Coordinated Cloud-Radio Access Networks

    KAUST Repository

    Douik, Ahmed; Dahrouj, Hayssam; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2017-01-01

    In practical wireless systems, the successful implementation of resource allocation techniques strongly depends on the algorithmic complexity. Consider a cloud-radio access network (CRAN), where the central cloud is responsible for scheduling

  8. Impacts on the Voltage Profile of DC Distribution Network with DG Access

    Science.gov (United States)

    Tu, J. J.; Yin, Z. D.

    2017-07-01

    With the development of electronic, more and more distributed generations (DGs) access into grid and cause the research fever of direct current (DC) distribution network. Considering distributed generation (DG) location and capacity have great impacts on voltage profile, so use IEEE9 and IEEE33 typical circuit as examples, with DGs access in centralized and decentralized mode, to compare voltage profile in alternating and direct current (AC/DC) distribution network. Introducing the voltage change ratio as an evaluation index, so gets the general results on voltage profile of DC distributed network with DG access. Simulation shows that, in the premise of reasonable location and capacity, DC distribution network is more suitable for DG access.

  9. JavaScript Access to DICOM Network and Objects in Web Browser.

    Science.gov (United States)

    Drnasin, Ivan; Grgić, Mislav; Gogić, Goran

    2017-10-01

    Digital imaging and communications in medicine (DICOM) 3.0 standard provides the baseline for the picture archiving and communication systems (PACS). The development of Internet and various communication media initiated demand for non-DICOM access to PACS systems. Ever-increasing utilization of the web browsers, laptops and handheld devices, as opposed to desktop applications and static organizational computers, lead to development of different web technologies. The DICOM standard officials accepted those subsequently as tools of alternative access. This paper provides an overview of the current state of development of the web access technology to the DICOM repositories. It presents a different approach of using HTML5 features of the web browsers through the JavaScript language and the WebSocket protocol by enabling real-time communication with DICOM repositories. JavaScript DICOM network library, DICOM to WebSocket proxy and a proof-of-concept web application that qualifies as a DICOM 3.0 device were developed.

  10. Energy Saving Scheme Based On Traffic Forwarding For Optical Fiber Access Networks

    DEFF Research Database (Denmark)

    Lopez, G. Arturo Rodes; Estaran Tolosa, Jose Manuel; Vegas Olmos, Juan José

    2013-01-01

    We report on an energy saving block that regroups and powers off OLTs during low traffic periods, resulting in energy savings up to 87,5% in the central office of optical access networks.......We report on an energy saving block that regroups and powers off OLTs during low traffic periods, resulting in energy savings up to 87,5% in the central office of optical access networks....

  11. Asynchronous Free-Space Optical CDMA Communications System for Last-mile Access Network

    DEFF Research Database (Denmark)

    Jurado-Navas, Antonio; Raddo, Thiago R.; Sanches, Anderson L.

    2016-01-01

    We propose a new hybrid asynchronous OCDMA-FSO communications system for access network solutions. New ABER expressions are derived under gamma-gamma scintillation channels, where all users can surprisingly achieve error-free transmissions when FEC is employed.......We propose a new hybrid asynchronous OCDMA-FSO communications system for access network solutions. New ABER expressions are derived under gamma-gamma scintillation channels, where all users can surprisingly achieve error-free transmissions when FEC is employed....

  12. Knowledge in Access in Rural Interconnected Areas Network Phase ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Researchers will explore network management issues by -examining KariaNet's ... Institution Country. Lebanon. Institution Website. http://www.aub.edu.lb ... IDRC “unpacks women's empowerment” at McGill University Conference. Findings ...

  13. Optical Multiple Access Network (OMAN) for advanced processing satellite applications

    Science.gov (United States)

    Mendez, Antonio J.; Gagliardi, Robert M.; Park, Eugene; Ivancic, William D.; Sherman, Bradley D.

    1991-01-01

    An OMAN breadboard for exploring advanced processing satellite circuit switch applications is introduced. Network architecture, hardware trade offs, and multiple user interference issues are presented. The breadboard test set up and experimental results are discussed.

  14. Providing open-access online materials and hands-on sessions for GIS exercises

    Science.gov (United States)

    Oguchi, T.; Yamauchi, H.; Hayakawa, Y. S.

    2017-12-01

    Researchers of GIS (Geographical Information Systems/Sciences) in Japan have collaborated to provide materials for GIS lecture classes in universities for the last 20 years. The major outcomes include 1) a GIS core curriculum, 2) a GIS "body of knowledge" explaining the details of the curriculum, 3) a series of PowerPoint presentations, and 4) a comprehensive GIS textbook. However, materials for GIS exercises at university classes using GIS software have been limited in Japan. Therefore, we launched a project to provide such materials which will be available online and accessible by anybody. The materials cover broad basic aspects of GIS including geoscientific applications such as terrain analysis using digital elevation models. The materials utilize public-domain and open-source software packages such as QGIS and GRASS. The data used are also freely available ones such as those from the Geospatial Information Authority of Japan. The use of the GitHub platform to distribute the materials allow easier online interactions by both material producers and users. Selected sets of the materials have been utilized for hands-on activities including both official university classes and public instructions. We have been updating the materials based on the opinions of people who took the hands-on courses for better GIS education. The current materials are in Japanese, but we plan to translate some of them into English.

  15. Adaptive MAC-layer protocol for multiservice digital access via tree and branch communication networks

    Science.gov (United States)

    Sriram, Kotikalapudi; Li, Chia-Chang; Magill, Peter; Whitaker, Norman A.; Dail, James E.; Dajer, Miguel A.; Siller, Curtis A.

    1995-11-01

    Described here is an adaptive MAC-layer protocol that supports multiservice (STM and ATM) applications in the context of subscriber access to tree and branch (e.g., fiber-coaxial cable) networks. The protocol adapts to changing demands for a mix of circuit and cell mode applications, and efficiently allocates upstream and downstream bandwidth to a variety of bursty and isochronous traffic sources. In the case of a hybrid fiber-coaxial (HFC) network the protocol resides in customer premises equipment and a common head-end controller. A medium-access control (MAC) processor provides for dividing the time domain for a given digital bitstream into successive frames, each with multiple STM and ATM time slots. Within the STM region of a frame, variable length time slots are allocated to calls (e.g., telephony, video telephony) requiring different amounts of bandwidth. A contention access signaling channel is also provided in this region for call control and set-up requests. Within the ATM region fixed-length time slots accommodate one individual ATM cell. These ATM time slots may be reserved for a user for the duration of a call or burst of successive ATM cells, or shared via a contention process. At least one contention time slot is available for signaling messages related to ATM call control and set-up requests. Further, the fixed-length ATM time slots may be reserved by a user for the duration of a call, or shared through a contention process. This paper describes the MAC-layer protocol, its relation to circuit- and ATM- amenable applications, and its performance with respect to signaling throughput and latency, and bandwidth efficiency for several service scenarios.

  16. An Experimental Performance Measurement of Implemented Wireless Access Point for Interworking Wi-Fi and HSDPA Networks

    Science.gov (United States)

    Byun, Tae-Young

    This paper presents a prototype of WAP(Wireless Access Point) that provides the wireless Internet access anywhere. Implemented WAP can be equipped with various wireless WAN interfaces such as WCDMA and HSDPA. WAP in the IP mechanism has to process connection setup procedure to one wireless WAN. Also, WAP can provide connection management procedures to reconnect interrupted connection automatically. By using WAP, several mobile devices such as netbook, UMPC and smart-phone in a moving vehicle can access to HSDPA network simultaneously. So, it has more convenient for using the WAP when there are needs to access wireless Internet more than two mobile devices in restricted spaces such as car, train and ship.

  17. SoNeUCON_{ABC}Pro: an access control model for social networks with translucent user provenance

    OpenAIRE

    González Manzano, Lorena; Slaymaker, Mark; Fuentes García Romero de Tejada, José María de; Vayenas, Dimitris

    2018-01-01

    Proceedings of: SecureComm 2017 International Workshops, ATCS and SePrIoT, Niagara Falls, ON, Canada, October 22–25, 2017 Web-Based Social Networks (WBSNs) are used by millions of people worldwide. While WBSNs provide many benefits, privacy preservation is a concern. The management of access control can help to assure data is accessed by authorized users. However, it is critical to provide sufficient flexibility so that a rich set of conditions may be imposed by users. In this paper we coi...

  18. Upgrade of hybrid fibre coax networks towards bi-directional access

    NARCIS (Netherlands)

    Khoe, G.D.; Wolters, R.P.C.; Boom, van den H.P.A.; Prati, G.

    1997-01-01

    In this paper we describe an upgrade scenario for Hybrid Fibre Coax (HFC) CATV Networks towards hi-directional access. The communication system described has been newly designed, and is based on the use of Direct Sequence- Code Division Multiple-Access (DS-CDMA). Due to its spread-spectrum

  19. Community access networks: how to connect the next billion to the ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Community access networks: how to connect the next billion to the Internet. Despite recent progress with mobile technology diffusion, more than four billion people worldwide are unconnected and have limited access to global communication infrastructure. The cost of implementing connectivity infrastructure in underserved ...

  20. Joint Mode Selection and Resource Allocation for Downlink Fog Radio Access Networks Supported D2D

    Directory of Open Access Journals (Sweden)

    Xiang Hongyu

    2015-09-01

    Full Text Available Presented as an innovative paradigm incorporating the cloud computing into radio access network, Cloud radio access networks (C-RANs have been shown advantageous in curtailing the capital and operating expenditures as well as providing better services to the customers. However, heavy burden on the non-ideal fronthaul limits performances of CRANs. Here we focus on the alleviation of burden on the fronthaul via the edge devices’ caches and propose a fog computing based RAN (F-RAN architecture with three candidate transmission modes: device to device, local distributed coordination, and global C-RAN. Followed by the proposed simple mode selection scheme, the average energy efficiency (EE of systems optimization problem considering congestion control is presented. Under the Lyapunov framework, the problem is reformulated as a joint mode selection and resource allocation problem, which can be solved by block coordinate descent method. The mathematical analysis and simulation results validate the benefits of F-RAN and an EE-delay tradeoff can be achieved by the proposed algorithm.

  1. Simple measurement-based admission control for DiffServ access networks

    Science.gov (United States)

    Lakkakorpi, Jani

    2002-07-01

    In order to provide good Quality of Service (QoS) in a Differentiated Services (DiffServ) network, a dynamic admission control scheme is definitely needed as an alternative to overprovisioning. In this paper, we present a simple measurement-based admission control (MBAC) mechanism for DiffServ-based access networks. Instead of using active measurements only or doing purely static bookkeeping with parameter-based admission control (PBAC), the admission control decisions are based on bandwidth reservations and periodically measured & exponentially averaged link loads. If any link load on the path between two endpoints is over the applicable threshold, access is denied. Link loads are periodically sent to Bandwidth Broker (BB) of the routing domain, which makes the admission control decisions. The information needed in calculating the link loads is retrieved from the router statistics. The proposed admission control mechanism is verified through simulations. Our results prove that it is possible to achieve very high bottleneck link utilization levels and still maintain good QoS.

  2. Converged wireline and wireless signal distribution in optical fiber access networks

    DEFF Research Database (Denmark)

    Prince, Kamau

    This thesis presents results obtained during the course of my doctoral studies into the transport of fixed and wireless signaling over a converged otpical access infrastructure. In the formulation, development and assessment of a converged paradigma for multiple-services delivery via optical access...... networking infrastructure, I have demonstrated increased functionalities with existing optical technologies and commercially available optoelectronic devices. I have developed novel systems for extending the range of optical access systems, and have demonstrated the repurposing of standard digital devices...

  3. Social Networks and Health: Understanding the Nuances of Healthcare Access between Urban and Rural Populations.

    Science.gov (United States)

    Amoah, Padmore Adusei; Edusei, Joseph; Amuzu, David

    2018-05-13

    Communities and individuals in many sub-Saharan African countries often face limited access to healthcare. Hence, many rely on social networks to enhance their chances for adequate health care. While this knowledge is well-established, little is known about the nuances of how different population groups activate these networks to improve access to healthcare. This paper examines how rural and urban dwellers in the Ashanti Region in Ghana distinctively and systematically activate their social networks to enhance access to healthcare. It uses a qualitative cross-sectional design, with in-depth interviews of 79 primary participants (28 urban and 51 rural residents) in addition to the views of eight community leaders and eight health personnel. It was discovered that both intimate and distanced social networks for healthcare are activated at different periods by rural and urban residents. Four main stages of social networks activation, comprising different individuals and groups were observed among rural and urban dwellers. Among both groups, physical proximity, privacy, trust and sense of fairness, socio-cultural meaning attached to health problems, and perceived knowledge and other resources (mainly money) held in specific networks inherently influenced social network activation. The paper posits that a critical analysis of social networks may help to tailor policy contents to individuals and groups with limited access to healthcare.

  4. DiffServ resource management in IP-based radio access networks

    NARCIS (Netherlands)

    Heijenk, Geert; Karagiannis, Georgios; Rexhepi, Vlora; Westberg, Lars; prof.dr. Prasad, R.; prof.dr. Bach Andersen, J.

    2001-01-01

    The increasing popularity of the Internet, the flexibility of IP, and the wide deployment of IP technologies, as well as the growth of mobile communications have driven the development of IP-based solutions for wireless networking. The introduction of IP-based transport in Radio Access Networks

  5. mCRAN: A radio access network architecture for 5G indoor ccommunications

    NARCIS (Netherlands)

    Chandra, Kishor; Cao, Zizheng; Bruintjes, Tom; Prasad, R.V.; Karagiannis, Georgios; Tangdiongga, E.; van den Boom, H.P.A.; Kokkeler, Andre B.J.

    2015-01-01

    Millimeter wave (mmWave) communication is being seen as a disruptive technology for 5G era. In particular, 60GHz frequency band has emerged as a promising candidate for multi-Gbps connectivity in indoor and hotspot areas. In terms of network architecture, cloud radio access network (CRAN) has

  6. mCRAN : a radio access network architecture for 5G indoor communications

    NARCIS (Netherlands)

    Chandra, Kishor; Cao, Zizheng; Bruintjes, T. M.; Prasad, R. Venkatesha; Karagiannis, G.; Tangdiongga, Eduward; van den Boom, H.P.A.; Kokkeler, A. B J

    2015-01-01

    Millimeter wave (mmWave) communication is being seen as a disruptive technology for 5G era. In particular, 60GHz frequency band has emerged as a promising candidate for multi-Gbps connectivity in indoor and hotspot areas. In terms of network architecture, cloud radio access network (CRAN) has

  7. The ENSDF radioactivity data base for IBM-PC and computer network access

    International Nuclear Information System (INIS)

    Ekstroem, P.; Spanier, L.

    1989-08-01

    A data base system for radioactivity gamma rays is described. A base with approximately 15000 gamma rays from 2777 decays is available for installation on the hard disk of a PC, and a complete system with approximately 73000 gamma rays is available for on-line access via the NORDic University computer NETwork (NORDUNET) and the Swedish University computer NETwork (SUNET)

  8. Clinical social networking--a new revolution in provider communication and delivery of clinical information across providers of care?

    Science.gov (United States)

    Kolowitz, Brian J; Lauro, Gonzalo Romero; Venturella, James; Georgiev, Veliyan; Barone, Michael; Deible, Christopher; Shrestha, Rasu

    2014-04-01

    The adoption of social media technologies appears to enhance clinical outcomes through improved communications as reported by Bacigalupe (Fam Syst Heal 29(1):1-14, 2011). The ability of providers to more effectively, directly, and rapidly communicate among themselves as well as with patients should strengthen collaboration and treatment as reported by Bacigalupe (Fam Syst Heal 29(1):1-14, 2011). This paper is a case study in one organization's development of an internally designed and developed social technology solution termed "Unite." The Unite system combines social technologies' features including push notifications, messaging, community groups, and user lists with clinical workflow and applications to construct dynamic provider networks, simplify communications, and facilitate clinical workflow optimization. Modeling Unite as a social technology may ease adoption barriers. Developing a social network that is integrated with healthcare information systems in the clinical space opens the doors to capturing and studying the way in which providers communicate. The Unite system appears to have the potential to breaking down existing communication paradigms. With Unite, a rich set of usage data tied to clinical events may unravel alternative networks that can be leveraged to advance patient care.

  9. Network Physics - the only company to provide physics-based network management - secures additional funding and new executives

    CERN Multimedia

    2003-01-01

    "Network Physics, the only provider of physics-based network management products, today announced an additional venture round of $6 million in funding, as well as the addition of David Jones as president and CEO and Tom Dunn as vice president of sales and business development" (1 page).

  10. Homeless Families' Education Networks: An Examination of Access and Mobilization

    Science.gov (United States)

    Miller, Peter M.

    2011-01-01

    Purpose: This study sought deeper understanding of how sheltered families accessed and mobilized educationally related relationships and resources during periods of homelessness. Such work is posited to be especially relevant considering that there is a growing crisis of family homelessness in the United States and school- and community-based…

  11. Ubiquitous access control and policy management in personal networks

    DEFF Research Database (Denmark)

    Kyriazanos, Dimitris M.; Stassinopoulos, George I.; Prasad, Neeli R.

    2006-01-01

    distributed master devices acting as access points- and also pure peer-to-peer interactions inside the PN. Taking benefit from the modularity and scalability of the design, this solution can be extended into supporting coalitions of different security domains, deriving from the creation of PNs federations....

  12. Public Access; Public Interest. The Network Project. Notebook Number 11.

    Science.gov (United States)

    Columbia Univ., New York, NY. Network Project.

    The transcript of a panel discussion and an essay on public access to and control of society's information resources are presented. It is contended that the electronic Media--including radio, television, and communication satellites--are controlled by a select group of individuals and corporations and that they are not meeting the public interest.…

  13. Robotics and telecommunication systems to provide better access to ultrasound expertise in the OR.

    Science.gov (United States)

    Angelini, L; Papaspyropoulos, V

    2000-01-01

    Surgery has begun to evolve as a result of the intense use of technological innovations. The result of this is better services for patients and enormous opportunities for the producers of biomedical instruments. The surgeon and the technologist are fast becoming allies in applying the latest developments of robotics, image treatment, simulation, sensors and telecommunications to surgery, in particular to the emerging field of minimally-invasive surgery. Ultrasonography is at present utilised both for diagnostic and therapeutic purposes in various fields. Intraoperative US examination can be of primary importance, especially when dealing with space-occupying lesions. The widening use of minimally-invasive surgery has furthered the development of US for use during this type of surgery. The success of a US examination requires not only a correct execution of the procedure, but also a correct interpretation of the images. We describe two projects that combine robotics and telecommunication systems to provide better access to US expertise in the operating room. The Midstep project has as its object the realisation of two robotic arms, one for the distant control of the US probe during laparoscopic surgery and the second to perform tele-interventional US. The second project, part of the Strategic CNR Project-'Robotics in Surgery', involves the realisation of a common platform for tracking and targeting surgical instruments in video-assisted surgery.

  14. Providing Open-Access Know How for Directors of Quantitative and Mathematics Support Centers

    Directory of Open Access Journals (Sweden)

    Michael Schuckers

    2017-01-01

    Full Text Available The purpose of this editorial is to introduce the quantitative literacy community to the newly published A Handbook for Directors of Quantitative and Mathematics Centers. QMaSCs (pronounced “Q-masks” can be broadly defined as centers that have supporting students in quantitative fields of study as part of their mission. Some focus only on calculus or mathematics; others concentrate on numeracy or quantitative literacy, and some do all of that. A QMaSC may be embedded in a mathematics department, or part of a learning commons, or a stand-alone center. There are hundreds of these centers in the U.S. The new handbook, which is the outgrowth of a 2013 NSF-sponsored, national workshop attended by 23 QMaSC directors from all quarters of the U.S., is available open access on the USF Scholar Commons and in hard copy from Amazon.com. This editorial by the handbook’s editors provides background and overview of the 20 detailed chapters on center leadership and management; community interactions; staffing, hiring and training; center assessment; and starting a center; and then a collection of ten case studies from research universities, four-year state colleges, liberal arts colleges, and a community college. The editorial ends by pointing out the need and potential benefits of a professional organization for QMaSC directors.

  15. Tablet based simulation provides a new solution to accessing laparoscopic skills training.

    Science.gov (United States)

    Bahsoun, Ali Nehme; Malik, Mohsan Munir; Ahmed, Kamran; El-Hage, Oussama; Jaye, Peter; Dasgupta, Prokar

    2013-01-01

    Access to facilities that allow trainees to develop their laparoscopic skills is very limited in the hospital environment and courses can be very expensive. We set out to build an inexpensive yet effective trainer to allow laparoscopic skill acquisition in the home or classroom environment based on using a tablet as a replacement for the laparoscopic stack and camera. The cavity in which to train was made from a cardboard box; we left the sides and back open to allow for natural light to fill the cavity. An iPad 2 (Apple Inc.) was placed over the box to act as our camera and monitor. We provided 10 experienced laparoscopic surgeons with the task of passing a suture needle through 3 hoops; then they filled in a questionnaire to assess Face (training capacity) and Content (performance) validity. On a 5-point Likert scale, the tablet-based laparoscopic trainer scored a mean 4.2 for training capacity (hand eye coordination, development, and maintenance of lap skills) and for performance (graphics, video, and lighting quality) it scored a mean 4.1. The iPad 2-based laparoscopic trainer was successfully validated for training. It allows students and trainees to practice at their own pace and for inexpensive training on the go. Future "app-"based skills are planned. Copyright © 2013 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  16. The challenges of M2M massive access in wireless cellular networks

    Directory of Open Access Journals (Sweden)

    Andrea Biral

    2015-02-01

    Full Text Available The next generation of communication systems, which is commonly referred to as 5G, is expected to support, besides the traditional voice and data services, new communication paradigms, such as Internet of Things (IoT and Machine-to-Machine (M2M services, which involve communication between Machine-Type Devices (MTDs in a fully automated fashion, thus, without or with minimal human intervention. Although the general requirements of 5G systems are progressively taking shape, the technological issues raised by such a vision are still partially unclear. Nonetheless, general consensus has been reached upon some specific challenges, such as the need for 5G wireless access networks to support massive access by MTDs, as a consequence of the proliferation of M2M services. In this paper, we describe the main challenges raised by the M2M vision, focusing in particular on the problems related to the support of massive MTD access in current cellular communication systems. Then we analyze the most common approaches proposed in the literature to enable the coexistence of conventional and M2M services in the current and next generation of cellular wireless systems. We finally conclude by pointing out the research challenges that require further investigation in order to provide full support to the M2M paradigm.

  17. Revenue-Maximizing Radio Access Technology Selection with Net Neutrality Compliance in Heterogeneous Wireless Networks

    Directory of Open Access Journals (Sweden)

    Elissar Khloussy

    2018-01-01

    Full Text Available The net neutrality principle states that users should have equal access to all Internet content and that Internet Service Providers (ISPs should not practice differentiated treatment on any of the Internet traffic. While net neutrality aims to restrain any kind of discrimination, it also grants exemption to a certain category of traffic known as specialized services (SS, by allowing the ISP to dedicate part of the resources for the latter. In this work, we consider a heterogeneous LTE/WiFi wireless network and we investigate revenue-maximizing Radio Access Technology (RAT selection strategies that are net neutrality-compliant, with exemption granted to SS traffic. Our objective is to find out how the bandwidth reservation for SS traffic would be made in a way that allows maximizing the revenue while being in compliance with net neutrality and how the choice of the ratio of reserved bandwidth would affect the revenue. The results show that reserving bandwidth for SS traffic in one RAT (LTE can achieve higher revenue. On the other hand, when the capacity is reserved across both LTE and WiFi, higher social benefit in terms of number of admitted users can be realized, as well as lower blocking probability for the Internet access traffic.

  18. Virus spreading in wireless sensor networks with a medium access control mechanism

    International Nuclear Information System (INIS)

    Wang Ya-Qi; Yang Xiao-Yuan

    2013-01-01

    In this paper, an extended version of standard susceptible-infected (SI) model is proposed to consider the influence of a medium access control mechanism on virus spreading in wireless sensor networks. Theoretical analysis shows that the medium access control mechanism obviously reduces the density of infected nodes in the networks, which has been ignored in previous studies. It is also found that by increasing the network node density or node communication radius greatly increases the number of infected nodes. The theoretical results are confirmed by numerical simulations. (general)

  19. Power Allocation and Outage Probability Analysis for SDN-based Radio Access Networks

    Science.gov (United States)

    Zhao, Yongxu; Chen, Yueyun; Mai, Zhiyuan

    2018-01-01

    In this paper, performance of Access network Architecture based SDN (Software Defined Network) is analyzed with respect to the power allocation issue. A power allocation scheme PSO-PA (Particle Swarm Optimization-power allocation) algorithm is proposed, the proposed scheme is subjected to constant total power with the objective of minimizing system outage probability. The entire access network resource configuration is controlled by the SDN controller, then it sends the optimized power distribution factor to the base station source node (SN) and the relay node (RN). Simulation results show that the proposed scheme reduces the system outage probability at a low complexity.

  20. Market opening and third party access in district heating networks

    International Nuclear Information System (INIS)

    Soederholm, Patrik; Warell, Linda

    2011-01-01

    The purpose of this paper is to analyse the possible effects of introducing TPA in district heating networks by identifying and scrutinizing a number of possible scenarios for increased competition. The analysis builds on a theoretical discussion of economic efficiency in district heating operations, and the possible impacts on consumer prices of a market opening. An important conclusion is that regulated TPA may have small positive effects on competition, and at the same time it can have a negative impact on the possibility to run the integrated district heating operations in a cost-effective manner. This conclusion stems in part from the observation that most district heating networks are local in scope. Moreover, district heating operations are highly interdependent in, for instance, that the level of the return temperature of the water will affect the efficiency of combined heat and power plants. For these reasons, the introduction of the so-called single-buyer model or, perhaps even more preferable, an extended and more transparent producer market could represent more efficient market designs. Moreover, in networks with clear natural monopoly characteristics an ex ante price regulation must be considered. - Research Highlights: →The paper analyses the possible effects of TPA in district heating networks. → Four possible scenarios for increased competition are identified and scrutinized. → A conclusion is that regulated TPA have only small positive effects on competition. → District heating operations are highly interdependent and separation can be costly.

  1. Adaptive Information Access on Multiple Applications Support Wireless Sensor Networks

    DEFF Research Database (Denmark)

    Tobgay, Sonam; Olsen, Rasmus Løvenstein; Prasad, Ramjee

    2014-01-01

    information is challenged by dynamic nature of information elements. These challenges are more prominent in case of wireless sensor network (WSN) applications, as the information that the sensor node collects are mostly dynamic in nature (say, temperature). Therefore, it is likely that there can be a mismatch...

  2. Adaptive Information Access in Multiple Applications Support Wireless Sensor Network

    DEFF Research Database (Denmark)

    Tobgay, Sonam; Olsen, Rasmus Løvenstein; Prasad, Ramjee

    2012-01-01

    Nowadays, due to wide applicability of Wireless Sensor Network (WSN) added by the low cost sensor devices, its popularity among the researchers and industrialists are very much visible. A substantial amount of works can be seen in the literature on WSN which are mainly focused on application...

  3. Requirements and Algorithms for Cooperation of Heterogeneous Radio Access Networks

    DEFF Research Database (Denmark)

    Mihovska, Albena D.; Tragos, Elias; Mino, Emilio

    2009-01-01

    systems.The RRM mechanisms are evaluated for the scenario of intra-RAN and inter-RAN user mobility. The RRM framework incorporates as novelty improved triggering mechanisms, a network-controlledmobility management scheme with policy enforcement on different levels in the RANarchitecture, and a distributed...

  4. Network of Research Infrastructures for European Seismology (NERIES)—Web Portal Developments for Interactive Access to Earthquake Data on a European Scale

    OpenAIRE

    A. Spinuso; L. Trani; S. Rives; P. Thomy; F. Euchner; Danijel Schorlemmer; Joachim Saul; Andres Heinloo; R. Bossu; T. van Eck

    2009-01-01

    The Network of Research Infrastructures for European Seismology (NERIES) is European Commission (EC) project whose focus is networking together seismological observatories and research institutes into one integrated European infrastructure that provides access to data and data products for research. Seismological institutes and organizations in European and Mediterranean countries maintain large, geographically distributed data archives, therefore this scenario suggested a design approach bas...

  5. Throughput Fairness Enhancement Using Differentiated Channel Access in Heterogeneous Sensor Networks

    Directory of Open Access Journals (Sweden)

    James Jong Hyuk Park

    2011-06-01

    Full Text Available Nowadays, with wireless sensor networks (WSNs being widely applied to diverse applications, heterogeneous sensor networks (HSNs, which can simultaneously support multiple sensing tasks in a common sensor field, are being considered as the general form of WSN system deployment. In HSNs, each application generates data packets with a different size, thereby resulting in fairness issues in terms of the network performance. In this paper, we present the design and performance evaluation of a differentiated channel access scheme (abbreviated to DiffCA to resolve the fairness problem in HSNs. DiffCA achieves fair performance among the application groups by providing each node with an additional backoff counter, whose value varies according to the size of the packets. A mathematical model based on the discrete time Markov chain is presented and is analyzed to measure the performance of DiffCA. The numerical results show that the performance degradation of disadvantaged application groups can be effectively compensated for by DiffCA. Simulation results are given to verify the accuracy of the numerical model.

  6. Throughput fairness enhancement using differentiated channel access in heterogeneous sensor networks.

    Science.gov (United States)

    Kim, Eui-Jik; Shon, Taeshik; Park, James Jong Hyuk; Jeong, Young-Sik

    2011-01-01

    Nowadays, with wireless sensor networks (WSNs) being widely applied to diverse applications, heterogeneous sensor networks (HSNs), which can simultaneously support multiple sensing tasks in a common sensor field, are being considered as the general form of WSN system deployment. In HSNs, each application generates data packets with a different size, thereby resulting in fairness issues in terms of the network performance. In this paper, we present the design and performance evaluation of a differentiated channel access scheme (abbreviated to DiffCA) to resolve the fairness problem in HSNs. DiffCA achieves fair performance among the application groups by providing each node with an additional backoff counter, whose value varies according to the size of the packets. A mathematical model based on the discrete time Markov chain is presented and is analyzed to measure the performance of DiffCA. The numerical results show that the performance degradation of disadvantaged application groups can be effectively compensated for by DiffCA. Simulation results are given to verify the accuracy of the numerical model.

  7. Free-space optics technology employed in an UMTS release 4 bearer independent core network access part

    Science.gov (United States)

    Bibac, Ionut

    2005-08-01

    The UMTS Bearer Independent Core Network program introduced the 3rd Generation Partnership Program Release 4 BICN architecture into the legacy UMTS TDM-switched network. BICN is the application of calI server archltecture for voice and circuit switched data, enabling the provisioning of traditional circuit-switched services using a packet-switched transport network. Today"s business climate has made it essential for service providers to develop a comprehensive networking strategy that means introduction of RCBICN networks. The R4-BICN solution to the evolution of the Core Network in UMTS will enable operators to significantly reduce the capital and operational costs of delivering both traditional voice sewices and new multimedia services. To build the optical backbone, which can support the third generation (3G) packetized infrastructure, the operators could choose a fibre connection, or they could retain the benefits of a wireless connectivity by using a FSO - Free Space Optical lmk, the only wireless technology available that is capable of achieving data rates up to 2.4 Gbit/s. FSO offers viable alternatives for both core transmission networks and for replacing microwaves links in NodeB - RNC access networks. The paper and presentation aim to demonstrate the manner in which FSO products and networks are employed into R4-BICN design solutions.

  8. Data Access Based on a Guide Map of the Underwater Wireless Sensor Network.

    Science.gov (United States)

    Wei, Zhengxian; Song, Min; Yin, Guisheng; Song, Houbing; Wang, Hongbin; Ma, Xuefei; Cheng, Albert M K

    2017-10-17

    Underwater wireless sensor networks (UWSNs) represent an area of increasing research interest, as data storage, discovery, and query of UWSNs are always challenging issues. In this paper, a data access based on a guide map (DAGM) method is proposed for UWSNs. In DAGM, the metadata describes the abstracts of data content and the storage location. The center ring is composed of nodes according to the shortest average data query path in the network in order to store the metadata, and the data guide map organizes, diffuses and synchronizes the metadata in the center ring, providing the most time-saving and energy-efficient data query service for the user. For this method, firstly the data is stored in the UWSN. The storage node is determined, the data is transmitted from the sensor node (data generation source) to the storage node, and the metadata is generated for it. Then, the metadata is sent to the center ring node that is the nearest to the storage node and the data guide map organizes the metadata, diffusing and synchronizing it to the other center ring nodes. Finally, when there is query data in any user node, the data guide map will select a center ring node nearest to the user to process the query sentence, and based on the shortest transmission delay and lowest energy consumption, data transmission routing is generated according to the storage location abstract in the metadata. Hence, specific application data transmission from the storage node to the user is completed. The simulation results demonstrate that DAGM has advantages with respect to data access time and network energy consumption.

  9. Sophisticated Online Learning Scheme for Green Resource Allocation in 5G Heterogeneous Cloud Radio Access Networks

    KAUST Repository

    Alqerm, Ismail

    2018-01-23

    5G is the upcoming evolution for the current cellular networks that aims at satisfying the future demand for data services. Heterogeneous cloud radio access networks (H-CRANs) are envisioned as a new trend of 5G that exploits the advantages of heterogeneous and cloud radio access networks to enhance spectral and energy efficiency. Remote radio heads (RRHs) are small cells utilized to provide high data rates for users with high quality of service (QoS) requirements, while high power macro base station (BS) is deployed for coverage maintenance and low QoS users service. Inter-tier interference between macro BSs and RRHs and energy efficiency are critical challenges that accompany resource allocation in H-CRANs. Therefore, we propose an efficient resource allocation scheme using online learning, which mitigates interference and maximizes energy efficiency while maintaining QoS requirements for all users. The resource allocation includes resource blocks (RBs) and power. The proposed scheme is implemented using two approaches: centralized, where the resource allocation is processed at a controller integrated with the baseband processing unit and decentralized, where macro BSs cooperate to achieve optimal resource allocation strategy. To foster the performance of such sophisticated scheme with a model free learning, we consider users\\' priority in RB allocation and compact state representation learning methodology to improve the speed of convergence and account for the curse of dimensionality during the learning process. The proposed scheme including both approaches is implemented using software defined radios testbed. The obtained results and simulation results confirm that the proposed resource allocation solution in H-CRANs increases the energy efficiency significantly and maintains users\\' QoS.

  10. Ethernet access network based on free-space optic deployment technology

    Science.gov (United States)

    Gebhart, Michael; Leitgeb, Erich; Birnbacher, Ulla; Schrotter, Peter

    2004-06-01

    The satisfaction of all communication needs from single households and business companies over a single access infrastructure is probably the most challenging topic in communications technology today. But even though the so-called "Last Mile Access Bottleneck" is well known since more than ten years and many distribution technologies have been tried out, the optimal solution has not yet been found and paying commercial access networks offering all service classes are still rare today. Conventional services like telephone, radio and TV, as well as new and emerging services like email, web browsing, online-gaming, video conferences, business data transfer or external data storage can all be transmitted over the well known and cost effective Ethernet networking protocol standard. Key requirements for the deployment technology driven by the different services are high data rates to the single customer, security, moderate deployment costs and good scalability to number and density of users, quick and flexible deployment without legal impediments and high availability, referring to the properties of optical and wireless communication. We demonstrate all elements of an Ethernet Access Network based on Free Space Optic distribution technology. Main physical parts are Central Office, Distribution Network and Customer Equipment. Transmission of different services, as well as configuration, service upgrades and remote control of the network are handled by networking features over one FSO connection. All parts of the network are proven, the latest commercially available technology. The set up is flexible and can be adapted to any more specific need if required.

  11. Admission Control and Interference Management in Dynamic Spectrum Access Networks

    Directory of Open Access Journals (Sweden)

    Jorge Martinez-Bauset

    2010-01-01

    Full Text Available We study two important aspects to make dynamic spectrum access work in practice: the admission policy of secondary users (SUs to achieve a certain degree of quality of service and the management of the interference caused by SUs to primary users (PUs. In order to limit the forced termination probability of SUs, we evaluate the Fractional Guard Channel reservation scheme to give priority to spectrum handovers over new arrivals. We show that, contrary to what has been proposed, the throughput of SUs cannot be maximized by configuring the reservation parameter. We also study the interference caused by SUs to PUs. We propose and evaluate different mechanisms to reduce the interference, which are based on simple spectrum access algorithms for both PUs and SUs and channel repacking algorithms for SUs. Numerical results show that the reduction can be of one order of magnitude or more with respect to the random access case. Finally, we propose an adaptive admission control scheme that is able to limit simultaneously the forced termination probability of SUs and what we define as the probability of interference. Our scheme does not require any configuration parameters beyond the probability objectives. Besides, it is simple to implement and it can operate with any arrival process and distribution of the session duration.

  12. Free Access to Point of Care Resource Results in Increased Use and Satisfaction by Rural Healthcare Providers

    Directory of Open Access Journals (Sweden)

    Lindsay Alcock

    2016-12-01

    Full Text Available A Review of: Eldredge, J. D., Hall, L. J., McElfresh, K. R., Warner, T. D., Stromberg, T. L., Trost, J. T., & Jelinek, D. A. (2016. Rural providers’ access to online resources: A randomized controlled trial. Journal of the Medical Library Association, 104(1, 33-41. http://dx.doi.org/10.3163/1536-5050.104.1.005 Objective – To determine whether free access to the point of care (PoC resource Dynamed or the electronic book collection AccessMedicine was more useful to rural health care providers in answering clinical questions in terms of usage and satisfaction. Design – Randomized controlled trial. Setting – Rural New Mexico. Subjects – Twenty-eight health care providers (physicians, nurses, physician assistants, and pharmacists with no reported access to PoC resources, (specifically Dynamed and AccessMedicine or electronic textbook collections prior to enrollment.

  13. A Novel Dual Separate Paths (DSP) Algorithm Providing Fault-Tolerant Communication for Wireless Sensor Networks.

    Science.gov (United States)

    Tien, Nguyen Xuan; Kim, Semog; Rhee, Jong Myung; Park, Sang Yoon

    2017-07-25

    Fault tolerance has long been a major concern for sensor communications in fault-tolerant cyber physical systems (CPSs). Network failure problems often occur in wireless sensor networks (WSNs) due to various factors such as the insufficient power of sensor nodes, the dislocation of sensor nodes, the unstable state of wireless links, and unpredictable environmental interference. Fault tolerance is thus one of the key requirements for data communications in WSN applications. This paper proposes a novel path redundancy-based algorithm, called dual separate paths (DSP), that provides fault-tolerant communication with the improvement of the network traffic performance for WSN applications, such as fault-tolerant CPSs. The proposed DSP algorithm establishes two separate paths between a source and a destination in a network based on the network topology information. These paths are node-disjoint paths and have optimal path distances. Unicast frames are delivered from the source to the destination in the network through the dual paths, providing fault-tolerant communication and reducing redundant unicast traffic for the network. The DSP algorithm can be applied to wired and wireless networks, such as WSNs, to provide seamless fault-tolerant communication for mission-critical and life-critical applications such as fault-tolerant CPSs. The analyzed and simulated results show that the DSP-based approach not only provides fault-tolerant communication, but also improves network traffic performance. For the case study in this paper, when the DSP algorithm was applied to high-availability seamless redundancy (HSR) networks, the proposed DSP-based approach reduced the network traffic by 80% to 88% compared with the standard HSR protocol, thus improving network traffic performance.

  14. Building a multimodal network and determining individual accessibility by public transportation

    DEFF Research Database (Denmark)

    Djurhuus, Sune; Hansen, Henning Sten; Aadahl, Mette

    2016-01-01

    The increased availability of transit schedules from web sites or travel planners as well as more disaggregate data has led to a growing interest in creating individual public transportation accessibility measures. However, used extensively, standard GIS software does not have direct capabilities...... from a travel planner into a multimodal network model using simple SQL (structured query language) programming and standard GIS. The method presented here integrates all parts of travelling by public transportation from individual home addresses to all reachable transit stops within different travel....... The accessibility areas are created at morning rush hour for a study population of 29 447 individuals and a few examples of accessibility areas are presented. The results show a big difference in individual public transportation accessibility in the region. In addition, how the transit network is accessed, whether...

  15. Scheduling of network access for feedback-based embedded systems

    Science.gov (United States)

    Liberatore, Vincenzo

    2002-07-01

    nd communication capabilities. Examples range from smart dust embedded in building materials to networks of appliances in the home. Embedded devices will be deployed in unprecedented numbers, will enable pervasive distributed computing, and will radically change the way people interact with the surrounding environment [EGH00a]. The paper targets embedded systems and their real-time (RT) communication requirements. RT requirements arise from the

  16. Impact of the 'Providing Access to Continued Education' Programme on Repeat Teenage Pregnancy in the Bahamas.

    Science.gov (United States)

    Sakharkar, V P; Frankson, M A; Sakharkar, P R

    2015-05-15

    To determine the relationship of determinants such as age, ethnicity, education and sexual behaviour with repeat teenage pregnancy and to determine the impact of 'Providing Access to Continued Education' (PACE) programme in reducing repeat teenage pregnancy amongst its participants in The Bahamas. This retrospective cohort study included 397 attendees of the Adolescent Health Centre (AHC). Eighty-eight out of 139 registered participants completed the PACE programme. Data on age, ethnicity, education, sexual behaviour and repeat pregnancy in two years were analysed for descriptive statistics, and association of demographic characteristics and participation in the PACE programme with repeat pregnancy using the Chi-squared test. Mean age of participants was 16.4 ± 1.1 years; median school grade and mean grade point average (GPA) was 11 and 1.97 ± 0.7, respectively. The mean age at the first sexual activity was 14.9 ± 1.2 years. The mean age and number of sexual partners were 21 ± 4.3 years and 2 ± 1, respectively. Overall, repeat pregnancy rate was 39%: 37.4% amongst PACE registered and 31.8% amongst PACE completed mothers. No significant difference was observed in repeat pregnancy between registered and non-registered as well as those who completed the programme and those who did not. The odds ratio of 0.525 suggested that completion of the PACE programme had a moderate protective effect on reducing repeat pregnancy. Age, ethnicity, education and sexual behaviour showed no association with repeat pregnancy. The PACE programme did not reduce repeat pregnancy rate significantly. However, completion of the programme offered a moderate protection.

  17. [Self-owned versus accredited network: comparative cost analysis in a Brazilian health insurance provider].

    Science.gov (United States)

    Souza, Marcos Antônio de; Salvalaio, Dalva

    2010-10-01

    to analyze the cost of a self-owned network maintained by a Brazilian health insurance provider as compared to the price charged by accredited service providers, so as to identify whether or not the self-owned network is economically advantageous. for this exploratory study, the company's management reports were reviewed. The cost associated with the self-owned network was calculated based on medical and dental office visits and diagnostic/laboratory tests performed at one of the company's most representative facilities. The costs associated with third parties were derived from price tables used by the accredited network for the same services analyzed in the self-owned network. The full-cost method was used for cost quantification. Costs are presented as absolute values (in R$) and percent comparisons between self-owned network costs versus accredited network costs. overall, the self-owned network was advantageous for medical and dental consultations as well as diagnostic and laboratory tests. Pediatric and labor medicine consultations and x-rays were less costly in the accredited network. the choice of verticalization has economic advantages for the health care insurance operator in comparison with services provided by third parties.

  18. Using and joining a franchised private sector provider network in Myanmar.

    Science.gov (United States)

    O'Connell, Kathryn; Hom, Mo; Aung, Tin; Theuss, Marc; Huntington, Dale

    2011-01-01

    Quality is central to understanding provider motivations to join and remain within a social franchising network. Quality also appears as a key issue from the client's perspective, and may influence why a client chooses to use a franchised provider over another type of provider. The dynamic relationships between providers of social franchising clinics and clients who use these services have not been thoroughly investigated in the context of Myanmar, which has an established social franchising network. This study examines client motivations to use a Sun Quality Health network provider and provider motivations to join and remain in the Sun Quality Health network. Taken together, these two aims provide an opportunity to explore the symbiotic relationship between client satisfaction and provider incentives to increase the utilization of reproductive health care services. Results from a series of focus group discussions with clients of reproductive health services and franchised providers shows that women chose health services provided by franchised private sector general practitioners because of its perceived higher quality, associated with the availability of effective, affordable, drugs. A key finding of the study is associated with providers. Provider focus group discussions indicate that a principle determinate for joining and remaining in the Sun Quality Health Network was serving the poor.

  19. Using and joining a franchised private sector provider network in Myanmar.

    Directory of Open Access Journals (Sweden)

    Kathryn O'Connell

    Full Text Available BACKGROUND: Quality is central to understanding provider motivations to join and remain within a social franchising network. Quality also appears as a key issue from the client's perspective, and may influence why a client chooses to use a franchised provider over another type of provider. The dynamic relationships between providers of social franchising clinics and clients who use these services have not been thoroughly investigated in the context of Myanmar, which has an established social franchising network. This study examines client motivations to use a Sun Quality Health network provider and provider motivations to join and remain in the Sun Quality Health network. Taken together, these two aims provide an opportunity to explore the symbiotic relationship between client satisfaction and provider incentives to increase the utilization of reproductive health care services. METHODS AND FINDINGS: Results from a series of focus group discussions with clients of reproductive health services and franchised providers shows that women chose health services provided by franchised private sector general practitioners because of its perceived higher quality, associated with the availability of effective, affordable, drugs. A key finding of the study is associated with providers. Provider focus group discussions indicate that a principle determinate for joining and remaining in the Sun Quality Health Network was serving the poor.

  20. Using and Joining a Franchised Private Sector Provider Network in Myanmar

    Science.gov (United States)

    O'Connell, Kathryn; Hom, Mo; Aung, Tin; Theuss, Marc; Huntington, Dale

    2011-01-01

    Background Quality is central to understanding provider motivations to join and remain within a social franchising network. Quality also appears as a key issue from the client's perspective, and may influence why a client chooses to use a franchised provider over another type of provider. The dynamic relationships between providers of social franchising clinics and clients who use these services have not been thoroughly investigated in the context of Myanmar, which has an established social franchising network. This study examines client motivations to use a Sun Quality Health network provider and provider motivations to join and remain in the Sun Quality Health network. Taken together, these two aims provide an opportunity to explore the symbiotic relationship between client satisfaction and provider incentives to increase the utilization of reproductive health care services. Methods and Findings Results from a series of focus group discussions with clients of reproductive health services and franchised providers shows that women chose health services provided by franchised private sector general practitioners because of its perceived higher quality, associated with the availability of effective, affordable, drugs. A key finding of the study is associated with providers. Provider focus group discussions indicate that a principle determinate for joining and remaining in the Sun Quality Health Network was serving the poor. PMID:22180781

  1. IQ imbalance tolerable parallel-channel DMT transmission for coherent optical OFDMA access network

    Science.gov (United States)

    Jung, Sang-Min; Mun, Kyoung-Hak; Jung, Sun-Young; Han, Sang-Kook

    2016-12-01

    Phase diversity of coherent optical communication provides spectrally efficient higher-order modulation for optical communications. However, in-phase/quadrature (IQ) imbalance in coherent optical communication degrades transmission performance by introducing unwanted signal distortions. In a coherent optical orthogonal frequency division multiple access (OFDMA) passive optical network (PON), IQ imbalance-induced signal distortions degrade transmission performance by interferences of mirror subcarriers, inter-symbol interference (ISI), and inter-channel interference (ICI). We propose parallel-channel discrete multitone (DMT) transmission to mitigate transceiver IQ imbalance-induced signal distortions in coherent orthogonal frequency division multiplexing (OFDM) transmissions. We experimentally demonstrate the effectiveness of parallel-channel DMT transmission compared with that of OFDM transmission in the presence of IQ imbalance.

  2. A network collaboration implementing technology to improve medication dispensing and administration in critical access hospitals.

    Science.gov (United States)

    Wakefield, Douglas S; Ward, Marcia M; Loes, Jean L; O'Brien, John

    2010-01-01

    We report how seven independent critical access hospitals collaborated with a rural referral hospital to standardize workflow policies and procedures while jointly implementing the same health information technologies (HITs) to enhance medication care processes. The study hospitals implemented the same electronic health record, computerized provider order entry, pharmacy information systems, automated dispensing cabinets (ADC), and barcode medication administration systems. We conducted interviews and examined project documents to explore factors underlying the successful implementation of ADC and barcode medication administration across the network hospitals. These included a shared culture of collaboration; strategic sequencing of HIT component implementation; interface among HIT components; strategic placement of ADCs; disciplined use and sharing of workflow analyses linked with HIT applications; planning for workflow efficiencies; acquisition of adequate supply of HIT-related devices; and establishing metrics to monitor HIT use and outcomes.

  3. A New Prime Code for Synchronous Optical Code Division Multiple-Access Networks

    Directory of Open Access Journals (Sweden)

    Huda Saleh Abbas

    2018-01-01

    Full Text Available A new spreading code based on a prime code for synchronous optical code-division multiple-access networks that can be used in monitoring applications has been proposed. The new code is referred to as “extended grouped new modified prime code.” This new code has the ability to support more terminal devices than other prime codes. In addition, it patches subsequences with “0s” leading to lower power consumption. The proposed code has an improved cross-correlation resulting in enhanced BER performance. The code construction and parameters are provided. The operating performance, using incoherent on-off keying modulation and incoherent pulse position modulation systems, has been analyzed. The performance of the code was compared with other prime codes. The results demonstrate an improved performance, and a BER floor of 10−9 was achieved.

  4. A network of experimental forests and ranges: Providing soil solutions for a changing world

    Science.gov (United States)

    Mary Beth. Adams

    2010-01-01

    The network of experimental forests and ranges of the USDA Forest Service represents significant opportunities to provide soil solutions to critical issues of a changing world. This network of 81 experimental forests and ranges encompasses broad geographic, biological, climatic and physical scales, and includes long-term data sets, and long-term experimental...

  5. TheCellMap.org: A Web-Accessible Database for Visualizing and Mining the Global Yeast Genetic Interaction Network.

    Science.gov (United States)

    Usaj, Matej; Tan, Yizhao; Wang, Wen; VanderSluis, Benjamin; Zou, Albert; Myers, Chad L; Costanzo, Michael; Andrews, Brenda; Boone, Charles

    2017-05-05

    Providing access to quantitative genomic data is key to ensure large-scale data validation and promote new discoveries. TheCellMap.org serves as a central repository for storing and analyzing quantitative genetic interaction data produced by genome-scale Synthetic Genetic Array (SGA) experiments with the budding yeast Saccharomyces cerevisiae In particular, TheCellMap.org allows users to easily access, visualize, explore, and functionally annotate genetic interactions, or to extract and reorganize subnetworks, using data-driven network layouts in an intuitive and interactive manner. Copyright © 2017 Usaj et al.

  6. A Fair Contention Access Scheme for Low-Priority Traffic in Wireless Body Area Networks

    Directory of Open Access Journals (Sweden)

    Shagufta Henna

    2017-08-01

    Full Text Available Recently, wireless body area networks (WBANs have attracted significant consideration in ubiquitous healthcare. A number of medium access control (MAC protocols, primarily derived from the superframe structure of the IEEE 802.15.4, have been proposed in literature. These MAC protocols aim to provide quality of service (QoS by prioritizing different traffic types in WBANs. A contention access period (CAPwith high contention in priority-based MAC protocols can result in higher number of collisions and retransmissions. During CAP, traffic classes with higher priority are dominant over low-priority traffic; this has led to starvation of low-priority traffic, thus adversely affecting WBAN throughput, delay, and energy consumption. Hence, this paper proposes a traffic-adaptive priority-based superframe structure that is able to reduce contention in the CAP period, and provides a fair chance for low-priority traffic. Simulation results in ns-3 demonstrate that the proposed MAC protocol, called traffic- adaptive priority-based MAC (TAP-MAC, achieves low energy consumption, high throughput, and low latency compared to the IEEE 802.15.4 standard, and the most recent priority-based MAC protocol, called priority-based MAC protocol (PA-MAC.

  7. Learning Automata Based Caching for Efficient Data Access in Delay Tolerant Networks

    Directory of Open Access Journals (Sweden)

    Zhenjie Ma

    2018-01-01

    Full Text Available Effective data access is one of the major challenges in Delay Tolerant Networks (DTNs that are characterized by intermittent network connectivity and unpredictable node mobility. Currently, different data caching schemes have been proposed to improve the performance of data access in DTNs. However, most existing data caching schemes perform poorly due to the lack of global network state information and the changing network topology in DTNs. In this paper, we propose a novel data caching scheme based on cooperative caching in DTNs, aiming at improving the successful rate of data access and reducing the data access delay. In the proposed scheme, learning automata are utilized to select a set of caching nodes as Caching Node Set (CNS in DTNs. Unlike the existing caching schemes failing to address the challenging characteristics of DTNs, our scheme is designed to automatically self-adjust to the changing network topology through the well-designed voting and updating processes. The proposed scheme improves the overall performance of data access in DTNs compared with the former caching schemes. The simulations verify the feasibility of our scheme and the improvements in performance.

  8. Accessibility in networks: A useful measure for understanding social insect nest architecture

    International Nuclear Information System (INIS)

    Viana, Matheus P.; Fourcassié, Vincent; Perna, Andrea; Costa, Luciano da F.; Jost, Christian

    2013-01-01

    Networks and the associated tools from graph theory have now become well-established approaches to study natural as well as human-made systems. While early studies focused on topology and connectivity, the recent literature has acknowledged the importance of the dynamical properties of these networks. Here we focus on such a dynamic measure: accessibility. It characterizes for any given movement dynamics (such as random walks) the average number of nodes that can be reached in exactly h steps (out-accessibility), or the average number of nodes from which a given node can be reached (in-accessibility). This focus on dynamics makes accessibility particularly appropriate to study movement on networks and to detect complementary properties with respect to topology-based measurements such as betweenness centrality. We apply this measure to six nests of Cubitermes termites. Their mushroom-like 3D architectures consist of chambers and connecting tunnels that can be associated to nodes and edges in a communication network. Accessibilities turn out to be particularly low in the bottom part of the nests that link them to their underground tunneling network. We interpret this result in the context of anti-predator (ants) behavior and/or as a side effect of the global nest shape.

  9. Securing optical code-division multiple-access networks with a postswitching coding scheme of signature reconfiguration

    Science.gov (United States)

    Huang, Jen-Fa; Meng, Sheng-Hui; Lin, Ying-Chen

    2014-11-01

    The optical code-division multiple-access (OCDMA) technique is considered a good candidate for providing optical layer security. An enhanced OCDMA network security mechanism with a pseudonoise (PN) random digital signals type of maximal-length sequence (M-sequence) code switching to protect against eavesdropping is presented. Signature codes unique to individual OCDMA-network users are reconfigured according to the register state of the controlling electrical shift registers. Examples of signature reconfiguration following state switching of the controlling shift register for both the network user and the eavesdropper are numerically illustrated. Dynamically changing the PN state of the shift register to reconfigure the user signature sequence is shown; this hinders eavesdroppers' efforts to decode correct data sequences. The proposed scheme increases the probability of eavesdroppers committing errors in decoding and thereby substantially enhances the degree of an OCDMA network's confidentiality.

  10. Online medical books: their availability and an assessment of how health sciences libraries provide access on their public Websites.

    Science.gov (United States)

    MacCall, Steven L

    2006-01-01

    The objective of this study was to determine the number and topical range of available online medical books and to assess how health sciences libraries were providing access to these resources on their public Websites. The collection-based evaluative technique of list checking was used to assess the number and topical range of online medical books of the six largest publishers. Publisher inventory lists were downloaded over a two-day period (May 16-17, 2004). Titles were counted and compared with the 2003 Brandon/Hill list. A sample of health sciences libraries was subsequently derived by consulting the 2004 "Top Medical Schools-Research" in U.S. News & World Report. Bibliographic and bibliothecal access methods were evaluated based on an inspection of the publicly available Websites of the sample libraries. Of 318 currently published online medical books, 151 (47%) were Brandon/Hill titles covering 42 of 59 Brandon/Hill topics (71%). These 151 titles represented 22% (N = 672) of the Brandon/Hill list, which further broke down as 52 minimal core, 41 initial purchase, and 58 other recommended Brandon/Hill titles. These numbers represented 50%, 28%, and 12%, respectively, of all Brandon/Hill titles corresponding to those categories. In terms of bibliographic access, 20 of 21 of sampled libraries created catalog records for their online medical books, 1 of which also provided analytical access at the chapter level, and none provided access at the chapter section level. Of the 21 libraries, 19 had library Website search engines that provided title-level access and 4 provided access at the chapter level and none that at the chapter section level. For bibliothecal access, 19 of 21 libraries provided title-level access to medical books, 8 of which provided classified and alphabetic arrangements, 1 provided a classified arrangement only, and 10 provided an alphabetic arrangement only. No library provided a bibliothecal arrangement for medical book chapters or chapter

  11. Scheduling Data Access in Smart Grid Networks Utilizing Context Information

    DEFF Research Database (Denmark)

    Findrik, Mislav; Grønbæk, Jesper; Olsen, Rasmus Løvenstein

    2014-01-01

    Current electrical grid is facing increased penetration of intermittent energy resources, in particular wind and solar energy. Fast variability of the power supply due to renewable energy resources can be balanced out using different energy storage systems or shifting the loads. Efficiently...... managing this fast flexibility requires two-way data exchange between a controller and sensors/meters via communication networks. In this paper we investigated scheduling of data collection utilizing meta-data from sensors that are describing dynamics of information. We show the applicability...

  12. Geographic Disparities in Access to Agencies Providing Income-Related Social Services.

    Science.gov (United States)

    Bauer, Scott R; Monuteaux, Michael C; Fleegler, Eric W

    2015-10-01

    Geographic location is an important factor in understanding disparities in access to health-care and social services. The objective of this cross-sectional study is to evaluate disparities in the geographic distribution of income-related social service agencies relative to populations in need within Boston. Agency locations were obtained from a comprehensive database of social services in Boston. Geographic information systems mapped the spatial relationship of the agencies to the population using point density estimation and was compared to census population data. A multivariate logistic regression was conducted to evaluate factors associated with categories of income-related agency density. Median agency density within census block groups ranged from 0 to 8 agencies per square mile per 100 population below the federal poverty level (FPL). Thirty percent (n = 31,810) of persons living below the FPL have no access to income-related social services within 0.5 miles, and 77 % of persons living below FPL (n = 83,022) have access to 2 or fewer agencies. 27.0 % of Blacks, 30.1 % of Hispanics, and 41.0 % of non-Hispanic Whites with incomes below FPL have zero access. In conclusion, some neighborhoods in Boston with a high concentration of low-income populations have limited access to income-related social service agencies.

  13. Performance evaluation of multilevel modulation formats using partial response for capacity upgrade in access network with limited electronic bandwidth

    DEFF Research Database (Denmark)

    Madsen, Peter; Suhr, Lau Frejstrup; Rodríguez Páez, Juan Sebastián

    2016-01-01

    We present a successful experimental evaluation of 4 level Pulse Amplitude Modulation (4-PAM) and Duobinary modulation. An experimental performance evaluation is presented for Duobinary 4 PAM and other modulation formats. All modulation formants used, may be considered to be implemented in future...... Passive Optical Network (PON) class access networks with limited electrical bandwidth. We compared NRZ, Duobinary, 4-PAM and Duobinary 4-PAM operating at 9 Gbaud over 20 km single mode fiber. The results provides an insight and guidelines on the utilization of these advanced modulation formats....

  14. Network access charges, vertical integration, and property rights structure - experiences from the German electricity markets

    International Nuclear Information System (INIS)

    Growitsch, C.; Wein, T.

    2005-01-01

    After the deregulation of the German electricity markets in 1998, the German government opted for a regulatory regime called negotiated third party access, which would be subject to ex-post control by the federal cartel office. Network access charges for new competitors are based on contractual arrangements between energy producers and industrial consumers. As the electricity networks are incontestable natural monopolies, the local and regional network operators are able to set (monopolistic) charges at their own discretion, restricted only by the possible interference of the federal cartel office (Bundeskartellamt). In this paper we analyze if there is evidence for varying charging behaviour depending on the supplier's economic independence (structure of property rights) or its level of vertical integration. For this purpose, we hypothesise that incorporated and vertically integrated suppliers set different charges than independent utility companies. Multivariate estimations show a relation between network access charges and the network operator's economic independence as well as level of vertical integration: on the low voltage level for an estimated annual consumption of 1700 kW/h, vertically integrated firms set-in accordance with our hypothesis-significantly lower access charges than vertically separated suppliers, whereas incorporated network operators charge significantly higher charges compared to independent suppliers. These results could not have been confirmed for other consumptions or voltage levels. (author)

  15. Louisiana coastal GIS network: Graphical user interface for access to spatial data

    Science.gov (United States)

    Hiland, Matteson; McBride, Randolph A.; Davis, Donald; Braud, Dewitt; Streiffer, Henry; Jones, Farrell; Lewis, Anthony; Williams, S.

    1991-01-01

    Louisiana's coastal wetlands support a large percentage of the nation's seafood and fur industries, vast deposits of oil and natural gas, habitat for thousands of species of plants and animals, winter nesting grounds and migratory paths for numerous waterfowl, and many recreational resources enjoyed by residents and tourists. Louisiana's wetlands also have the highest rates of coastal erosion and wetland loss in the nation. While numerous studies across many disciplines have been conducted on both local and regional scales, no complete inventory exists for this information. The Louisiana Coastal Geographic Information System Network (LCGISN) is currently being developed to facilitate access to existing data for coastal zone planners, managers, and researchers. The Louisiana Geological Survey (LGS), in cooperation with the LSU Department of Geography and Anthropology, the Computer Aided Design and Geographic Information Systems Research Laboratory (CADGIS), and others, is pursuing this project under the terms of a cooperative agreement with the U.S. Geological Survey. LCGISN is an automated system for searching and retrieving geographic, cartographic, and bibliographic data. By linking original programming with an existing GIS software package and an industry standard relational database management system, LCGISN will provide the capability for users to search for data references by interactively defining the area of interest on a displayed map/image reference background. Several agencies will be networked to provide easy access to a wide variety of information. LCGISN, with its headquarters at LGS, will serve as the central node on the network, providing data format conversions, projection and datum transformations, and storage of several of the most commonly used data sets. Thematic mapper data, USGS 7.5-minute quadrangle map boundaries, political and legal boundaries, major transportation routes, and other digital data will provide a base map to aid the user in

  16. An open-access modeled passenger flow matrix for the global air network in 2010.

    Science.gov (United States)

    Huang, Zhuojie; Wu, Xiao; Garcia, Andres J; Fik, Timothy J; Tatem, Andrew J

    2013-01-01

    The expanding global air network provides rapid and wide-reaching connections accelerating both domestic and international travel. To understand human movement patterns on the network and their socioeconomic, environmental and epidemiological implications, information on passenger flow is required. However, comprehensive data on global passenger flow remain difficult and expensive to obtain, prompting researchers to rely on scheduled flight seat capacity data or simple models of flow. This study describes the construction of an open-access modeled passenger flow matrix for all airports with a host city-population of more than 100,000 and within two transfers of air travel from various publicly available air travel datasets. Data on network characteristics, city population, and local area GDP amongst others are utilized as covariates in a spatial interaction framework to predict the air transportation flows between airports. Training datasets based on information from various transportation organizations in the United States, Canada and the European Union were assembled. A log-linear model controlling the random effects on origin, destination and the airport hierarchy was then built to predict passenger flows on the network, and compared to the results produced using previously published models. Validation analyses showed that the model presented here produced improved predictive power and accuracy compared to previously published models, yielding the highest successful prediction rate at the global scale. Based on this model, passenger flows between 1,491 airports on 644,406 unique routes were estimated in the prediction dataset. The airport node characteristics and estimated passenger flows are freely available as part of the Vector-Borne Disease Airline Importation Risk (VBD-Air) project at: www.vbd-air.com/data.

  17. Unbundling in Current Broadband and Next-Generation Ultra-Broadband Access Networks

    Science.gov (United States)

    Gaudino, Roberto; Giuliano, Romeo; Mazzenga, Franco; Valcarenghi, Luca; Vatalaro, Francesco

    2014-05-01

    This article overviews the methods that are currently under investigation for implementing multi-operator open-access/shared-access techniques in next-generation access ultra-broadband architectures, starting from the traditional "unbundling-of-the-local-loop" techniques implemented in legacy twisted-pair digital subscriber line access networks. A straightforward replication of these copper-based unbundling-of-the-local-loop techniques is usually not feasible on next-generation access networks, including fiber-to-the-home point-to-multipoint passive optical networks. To investigate this issue, the article first gives a concise description of traditional copper-based unbundling-of-the-local-loop solutions, then focalizes on both next-generation access hybrid fiber-copper digital subscriber line fiber-to-the-cabinet scenarios and on fiber to the home by accounting for the mix of regulatory and technological reasons driving the next-generation access migration path, focusing mostly on the European situation.

  18. Random access to mobile networks with advanced error correction

    Science.gov (United States)

    Dippold, Michael

    1990-01-01

    A random access scheme for unreliable data channels is investigated in conjunction with an adaptive Hybrid-II Automatic Repeat Request (ARQ) scheme using Rate Compatible Punctured Codes (RCPC) Forward Error Correction (FEC). A simple scheme with fixed frame length and equal slot sizes is chosen and reservation is implicit by the first packet transmitted randomly in a free slot, similar to Reservation Aloha. This allows the further transmission of redundancy if the last decoding attempt failed. Results show that a high channel utilization and superior throughput can be achieved with this scheme that shows a quite low implementation complexity. For the example of an interleaved Rayleigh channel and soft decision utilization and mean delay are calculated. A utilization of 40 percent may be achieved for a frame with the number of slots being equal to half the station number under high traffic load. The effects of feedback channel errors and some countermeasures are discussed.

  19. Passive Optical Access Networks: State of the Art and Future Evolution

    Directory of Open Access Journals (Sweden)

    Tommaso Muciaccia

    2014-10-01

    Full Text Available In the very last years, optical access networks are growing very rapidly, from both the network operators and the research interests points of view. Fiber To The Home (FTTH is already a reality in plenty of real contexts and there has been a further stimulus to the proposal of new solutions and the investigation of new possibilities, in order to optimize network performance and reduce capital and operational expenditure. A complete and systematic overview of passive optical access networks is presented in this paper, concerning both the hot research topics and the main operative issues about the design guidelines and the deployment of Passive Optical Networks (PON architectures, nowadays the most commonly implemented approach to realize optical fiber links in the access networks. A comparison of advantages and disadvantages of different multiplexing techniques is discussed, with specific reference to WDM-based networks, almost universally considered as the enabling technology for future proof bandwidth requirements. An exhaustive summary is also given about the-state-of-the-art of modulation and encoding techniques recently proposed by the scientific community, as well as the open challenges (such as colorless and coolerless ONUs for telecom companies and international standardization compliance.

  20. 3. Informationsveranstaltung des Open Access Network Austria (OANA (Wien, 1. Juni 2016

    Directory of Open Access Journals (Sweden)

    Katharina Rieck

    2016-09-01

    Full Text Available Dieser Beitrag fasst die Ergebnisse der 3. OANA-Veranstaltung, die am 01.06.2016 im Palais Harrach in Wien stattfand, zusammen. Das „Open Access Network Austria“ (OANA ist eine „joint activity“ unter dem organisatorischen Dach des Fonds zur Förderung der wissenschaftlichen Forschung (FWF und der Österreichischen Universitätenkonferenz (UNIKO mit dem Ziel Open Access Aktivitäten in der österreichischen Forschungslandschaft zu koordinieren. Die fünf Arbeitsgruppen, die im Jänner 2015 gebildet wurden, präsentierten bei der Informationsveranstaltung die Ergebnisse und Fortschritte aus eineinhalb Jahren Arbeit. Ab Herbst 2016 werden sich vier neue Arbeitsgruppen mit den Themenschwerpunkten „Strategische Positionierung & Administration der Open-Access-Transition“, „Open Access & die Zukunft von Scholarly Communication“, „Open Access & Open Research Data“ und „Open Access & Open Educational Resources“ beschäftigen.

  1. A novel root-index based prioritized random access scheme for 5G cellular networks

    Directory of Open Access Journals (Sweden)

    Taehoon Kim

    2015-12-01

    Full Text Available Cellular networks will play an important role in realizing the newly emerging Internet-of-Everything (IoE. One of the challenging issues is to support the quality of service (QoS during the access phase, while accommodating a massive number of machine nodes. In this paper, we show a new paradigm of multiple access priorities in random access (RA procedure and propose a novel root-index based prioritized random access (RIPRA scheme that implicitly embeds the access priority in the root index of the RA preambles. The performance evaluation shows that the proposed RIPRA scheme can successfully support differentiated performance for different access priority levels, even though there exist a massive number of machine nodes.

  2. Capability-based Access Control Delegation Model on the Federated IoT Network

    DEFF Research Database (Denmark)

    Anggorojati, Bayu; Mahalle, Parikshit N.; Prasad, Neeli R.

    2012-01-01

    Flexibility is an important property for general access control system and especially in the Internet of Things (IoT), which can be achieved by access or authority delegation. Delegation mechanisms in access control that have been studied until now have been intended mainly for a system that has...... no resource constraint, such as a web-based system, which is not very suitable for a highly pervasive system such as IoT. To this end, this paper presents an access delegation method with security considerations based on Capability-based Context Aware Access Control (CCAAC) model intended for federated...... machine-to-machine communication or IoT networks. The main idea of our proposed model is that the access delegation is realized by means of a capability propagation mechanism, and incorporating the context information as well as secure capability propagation under federated IoT environments. By using...

  3. Energy-Efficient Boarder Node Medium Access Control Protocol for Wireless Sensor Networks

    Science.gov (United States)

    Razaque, Abdul; Elleithy, Khaled M.

    2014-01-01

    This paper introduces the design, implementation, and performance analysis of the scalable and mobility-aware hybrid protocol named boarder node medium access control (BN-MAC) for wireless sensor networks (WSNs), which leverages the characteristics of scheduled and contention-based MAC protocols. Like contention-based MAC protocols, BN-MAC achieves high channel utilization, network adaptability under heavy traffic and mobility, and low latency and overhead. Like schedule-based MAC protocols, BN-MAC reduces idle listening time, emissions, and collision handling at low cost at one-hop neighbor nodes and achieves high channel utilization under heavy network loads. BN-MAC is particularly designed for region-wise WSNs. Each region is controlled by a boarder node (BN), which is of paramount importance. The BN coordinates with the remaining nodes within and beyond the region. Unlike other hybrid MAC protocols, BN-MAC incorporates three promising models that further reduce the energy consumption, idle listening time, overhearing, and congestion to improve the throughput and reduce the latency. One of the models used with BN-MAC is automatic active and sleep (AAS), which reduces the ideal listening time. When nodes finish their monitoring process, AAS lets them automatically go into the sleep state to avoid the idle listening state. Another model used in BN-MAC is the intelligent decision-making (IDM) model, which helps the nodes sense the nature of the environment. Based on the nature of the environment, the nodes decide whether to use the active or passive mode. This decision power of the nodes further reduces energy consumption because the nodes turn off the radio of the transceiver in the passive mode. The third model is the least-distance smart neighboring search (LDSNS), which determines the shortest efficient path to the one-hop neighbor and also provides cross-layering support to handle the mobility of the nodes. The BN-MAC also incorporates a semi

  4. Energy-efficient boarder node medium access control protocol for wireless sensor networks.

    Science.gov (United States)

    Razaque, Abdul; Elleithy, Khaled M

    2014-03-12

    This paper introduces the design, implementation, and performance analysis of the scalable and mobility-aware hybrid protocol named boarder node medium access control (BN-MAC) for wireless sensor networks (WSNs), which leverages the characteristics of scheduled and contention-based MAC protocols. Like contention-based MAC protocols, BN-MAC achieves high channel utilization, network adaptability under heavy traffic and mobility, and low latency and overhead. Like schedule-based MAC protocols, BN-MAC reduces idle listening time, emissions, and collision handling at low cost at one-hop neighbor nodes and achieves high channel utilization under heavy network loads. BN-MAC is particularly designed for region-wise WSNs. Each region is controlled by a boarder node (BN), which is of paramount importance. The BN coordinates with the remaining nodes within and beyond the region. Unlike other hybrid MAC protocols, BN-MAC incorporates three promising models that further reduce the energy consumption, idle listening time, overhearing, and congestion to improve the throughput and reduce the latency. One of the models used with BN-MAC is automatic active and sleep (AAS), which reduces the ideal listening time. When nodes finish their monitoring process, AAS lets them automatically go into the sleep state to avoid the idle listening state. Another model used in BN-MAC is the intelligent decision-making (IDM) model, which helps the nodes sense the nature of the environment. Based on the nature of the environment, the nodes decide whether to use the active or passive mode. This decision power of the nodes further reduces energy consumption because the nodes turn off the radio of the transceiver in the passive mode. The third model is the least-distance smart neighboring search (LDSNS), which determines the shortest efficient path to the one-hop neighbor and also provides cross-layering support to handle the mobility of the nodes. The BN-MAC also incorporates a semi

  5. Energy-Efficient Boarder Node Medium Access Control Protocol for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Abdul Razaque

    2014-03-01

    Full Text Available This paper introduces the design, implementation, and performance analysis of the scalable and mobility-aware hybrid protocol named boarder node medium access control (BN-MAC for wireless sensor networks (WSNs, which leverages the characteristics of scheduled and contention-based MAC protocols. Like contention-based MAC protocols, BN-MAC achieves high channel utilization, network adaptability under heavy traffic and mobility, and low latency and overhead. Like schedule-based MAC protocols, BN-MAC reduces idle listening time, emissions, and collision handling at low cost at one-hop neighbor nodes and achieves high channel utilization under heavy network loads. BN-MAC is particularly designed for region-wise WSNs. Each region is controlled by a boarder node (BN, which is of paramount importance. The BN coordinates with the remaining nodes within and beyond the region. Unlike other hybrid MAC protocols, BN-MAC incorporates three promising models that further reduce the energy consumption, idle listening time, overhearing, and congestion to improve the throughput and reduce the latency. One of the models used with BN-MAC is automatic active and sleep (AAS, which reduces the ideal listening time. When nodes finish their monitoring process, AAS lets them automatically go into the sleep state to avoid the idle listening state. Another model used in BN-MAC is the intelligent decision-making (IDM model, which helps the nodes sense the nature of the environment. Based on the nature of the environment, the nodes decide whether to use the active or passive mode. This decision power of the nodes further reduces energy consumption because the nodes turn off the radio of the transceiver in the passive mode. The third model is the least-distance smart neighboring search (LDSNS, which determines the shortest efficient path to the one-hop neighbor and also provides cross-layering support to handle the mobility of the nodes. The BN-MAC also incorporates a semi

  6. College Access and Success for Students Experiencing Homelessness: A Toolkit for Educators and Service Providers

    Science.gov (United States)

    Dukes, Christina

    2013-01-01

    This toolkit serves as a comprehensive resource on the issue of higher education access and success for homeless students, including information on understanding homeless students, assisting homeless students in choosing a school, helping homeless students pay for application-related expenses, assisting homeless students in finding financial aid…

  7. The Role of Women's Colleges and Universities in Providing Access to Postsecondary Education

    Science.gov (United States)

    Renn, Kristen A.

    2017-01-01

    Based on a qualitative, comparative, multiple case study of the contributions and status of 21st century women's colleges and universities, this article analyzes the topic of women's access to postsecondary education in ten nations. Despite decreasing numbers of women-only institutions in some regions (e.g., North America), the sector is growing…

  8. Allocation and management issues in multiple-transaction open access transmission networks

    Science.gov (United States)

    Tao, Shu

    This thesis focuses on some key issues related to allocation and management by the independent grid operator (IGO) of unbundled services in multiple-transaction open access transmission networks. The three unbundled services addressed in the thesis are transmission real power losses, reactive power support requirements from generation sources, and transmission congestion management. We develop the general framework that explicitly represents multiple transactions undertaken simultaneously in the transmission grid. This framework serves as the basis for formulating various problems treated in the thesis. We use this comprehensive framework to develop a physical-flow-based mechanism to allocate the total transmission losses to each transaction using the system. An important property of the allocation scheme is its capability to effectively deal with counter flows that result in the presence of specific transactions. Using the loss allocation results as the basis, we construct the equivalent loss compensation concept and apply it to develop flexible and effective procedures for compensating losses in multiple-transaction networks. We present a new physical-flow-based mechanism for allocating the reactive power support requirements provided by generators in multiple-transaction networks. The allocatable reactive support requirements are formulated as the sum of two specific components---the voltage magnitude variation component and the voltage angle variation component. The formulation utilizes the multiple-transaction framework and makes use of certain simplifying approximations. The formulation leads to a natural allocation as a function of the amount of each transaction. The physical interpretation of each allocation as a sensitivity of the reactive output of a generator is discussed. We propose a congestion management allocation scheme for multiple-transaction networks. The proposed scheme determines the allocation of congestion among the transactions on a physical

  9. A Method for Upper Bounding Long Term Growth of Network Access Speed

    Directory of Open Access Journals (Sweden)

    Thomas Phillip Knudsen

    2006-06-01

    Full Text Available The development in home Internet access speed has shown an exponential development with growth rates averaging 25% per year. For resource management in network provisioning it becomes an urgent question how long such growth can continue. This paper presents a method for calculating an upper bound to visual content driven growth, proceeding from datarate requirements for a full virtual environment. Scenarios and approaches for reducing datarate requirements are considered and discussed. The presented figures for an upper bound on network access speed are discussed and perspectives on further research presented.

  10. A Method for Upper Bounding Long Term Growth of Network Access Speed

    DEFF Research Database (Denmark)

    Knudsen, Thomas Phillip; Pedersen, Jens Myrup; Madsen, Ole Brun

    2004-01-01

    The development in home Internet access speed has shown an exponential development with growth rates averaging 25% per year. For resource management in network provisioning it becomes an urgent question how long such growth can continue. This paper presents a method for calculating an upper bound...... to visual content driven growth, proceeding from datarate requirements for a full virtual environment. Scenarios and approaches for reducing datarate requirements are considered and discussed. The presented figures for an upper bound on network access speed are discussed and perspectives on further research...

  11. Modeling the video distribution link in the Next Generation Optical Access Networks

    DEFF Research Database (Denmark)

    Amaya, F.; Cárdenas, A.; Tafur Monroy, Idelfonso

    2011-01-01

    In this work we present a model for the design and optimization of the video distribution link in the next generation optical access network. We analyze the video distribution performance in a SCM-WDM link, including the noise, the distortion and the fiber optic nonlinearities. Additionally, we...... consider in the model the effect of distributed Raman amplification, used to extent the capacity and the reach of the optical link. In the model, we use the nonlinear Schrödinger equation with the purpose to obtain capacity limitations and design constrains of the next generation optical access networks....

  12. Modeling the video distribution link in the Next Generation Optical Access Networks

    International Nuclear Information System (INIS)

    Amaya, F; Cardenas, A; Tafur, I

    2011-01-01

    In this work we present a model for the design and optimization of the video distribution link in the next generation optical access network. We analyze the video distribution performance in a SCM-WDM link, including the noise, the distortion and the fiber optic nonlinearities. Additionally, we consider in the model the effect of distributed Raman amplification, used to extent the capacity and the reach of the optical link. In the model, we use the nonlinear Schroedinger equation with the purpose to obtain capacity limitations and design constrains of the next generation optical access networks.

  13. Intelligent Security Auditing Based on Access Control of Devices in Ad Hoc Network

    Institute of Scientific and Technical Information of China (English)

    XU Guang-wei; SHI You-qun; ZHU Ming; WU Guo-wen; CAO Qi-ying

    2006-01-01

    Security in Ad Hoc network is an important issue under the opening circumstance of application service. Some protocols and models of security auditing have been proposed to ensure rationality of contracting strategy and operating regulation and used to identify abnormal operation. Model of security auditing based on access control of devices will be advanced to register sign of devices and property of event of access control and to audit those actions. In the end, the model is analyzed and simulated.

  14. Acoustic Metadata Management and Transparent Access to Networked Oceanographic Data Sets

    Science.gov (United States)

    2015-09-30

    Transparent Access to Networked Oceanographic Data Sets Marie A. Roch Dept. of Computer Science San Diego State University 5500 Campanile Drive San...specific technologies for processing Excel spreadsheets and Access databases. The architecture (Figure 4) is based on a client-server model...Keesey, M. S., Lieske, J. H., Ostro, S. J., Standish, E. M., and Wimberly, R. N. (1996). "JPL’s On-Line Solar System Data Service," B. Am. Astron

  15. Low-complexity co-tier interference reduction scheme in open-access overlaid cellular networks

    KAUST Repository

    Radaydeh, Redha Mahmoud Mesleh

    2011-12-01

    This paper addresses the effect of co-tier interference on the performance of multiuser overlaid cellular networks that share the same available resources. It assumed that each macrocell contains a number of self-configurable and randomly located femtocells that employ the open-access control strategy to reduce the effect of cross-tier interference. It is also assumed that the desired user equipment (UE) can access only one of the available channels, maintains simple decoding circuitry with single receive antenna, and has limited knowledge of the instantaneous channel state information (CSI) due to resource limitation. To mitigate the effect of co-tier interference in the absence of the CSI of the desired UE, a low-complexity switched-based scheme for single channel selection based on the predicted interference levels associated with available channels is proposed for the case of over-loaded channels. Through the analysis, new general formulation for the statistics of the resulting instantaneous interference power and some performance measures are presented. The effect of the switching threshold on the efficiency and performance of the proposed scheme is studied. Numerical and simulation results to clarify the usefulness of the proposed scheme in reducing the impact of co-tier interference are also provided. © 2011 IEEE.

  16. Broadband and scalable mobile satellite communication system for future access networks

    Science.gov (United States)

    Ohata, Kohei; Kobayashi, Kiyoshi; Nakahira, Katsuya; Ueba, Masazumi

    2005-07-01

    Due to the recent market trends, NTT has begun research into next generation satellite communication systems, such as broadband and scalable mobile communication systems. One service application objective is to provide broadband Internet access for transportation systems, temporal broadband access networks and telemetries to remote areas. While these are niche markets the total amount of capacity should be significant. We set a 1-Gb/s total transmission capacity as our goal. Our key concern is the system cost, which means that the system should be unified system with diversified services and not tailored for each application. As satellites account for a large portion of the total system cost, we set the target satellite size as a small, one-ton class dry mass with a 2-kW class payload power. In addition to the payload power and weight, the mobile satellite's frequency band is extremely limited. Therefore, we need to develop innovative technologies that will reduce the weight and maximize spectrum and power efficiency. Another challenge is the need for the system to handle up to 50 dB and a wide data rate range of other applications. This paper describes the key communication system technologies; the frequency reuse strategy, multiplexing scheme, resource allocation scheme, and QoS management algorithm to ensure excellent spectrum efficiency and support a variety of services and quality requirements in the mobile environment.

  17. Channel Access and Power Control for Mobile Crowdsourcing in Device-to-Device Underlaid Cellular Networks

    Directory of Open Access Journals (Sweden)

    Yue Ma

    2018-01-01

    Full Text Available With the access of a myriad of smart handheld devices in cellular networks, mobile crowdsourcing becomes increasingly popular, which can leverage omnipresent mobile devices to promote the complicated crowdsourcing tasks. Device-to-device (D2D communication is highly desired in mobile crowdsourcing when cellular communications are costly. The D2D cellular network is more preferable for mobile crowdsourcing than conventional cellular network. Therefore, this paper addresses the channel access and power control problem in the D2D underlaid cellular networks. We propose a novel semidistributed network-assisted power and a channel access control scheme for D2D user equipment (DUE pieces. It can control the interference from DUE pieces to the cellular user accurately and has low information feedback overhead. For the proposed scheme, the stochastic geometry tool is employed and analytic expressions are derived for the coverage probabilities of both the cellular link and D2D links. We analyze the impact of key system parameters on the proposed scheme. The Pareto optimal access threshold maximizing the total area spectral efficiency is obtained. Unlike the existing works, the performances of the cellular link and D2D links are both considered. Simulation results show that the proposed method can improve the total area spectral efficiency significantly compared to existing schemes.

  18. Research and Design of Dynamic Migration Access Control Technology Based on Heterogeneous Network

    Directory of Open Access Journals (Sweden)

    Wang Feng

    2017-01-01

    Full Text Available With the continuous development of wireless networks, the amount of privacy services in heterogeneous mobile networks is increasing, such as information storage, user access, and so on. Access control security issues for heterogeneous mobile radio network, this paper proposes a dynamic migration access control technology based on heterogeneous network. Through the system architecture of the mutual trust system, we can understand the real-time mobile node failure or abnormal state. To make the service can be terminated for the node. And adopt the 802.1X authentication way to improve the security of the system. Finally, it by combining the actual running test data, the trust update algorithm of the system is optimized to reduce the actual security threats in the environment. Experiments show that the system’s anti-attack, the success rate of access, bit error rate is in line with the expected results. This system can effectively reduce the system authentication information is illegally obtained after the network security protection mechanism failure and reduce the risk of user data leakage.

  19. Will the Pell Grant Have the Ability To Provide Access and Choice to Low-Income Students in the Future?

    Science.gov (United States)

    Lechuga, Vicente M.

    This paper provides a basic understanding of the Pell Grant program and summarizes the evidence regarding its effectiveness. The Basic Educational Opportunities Program, known as the Pell Grant program, began in 1973 as a means of providing disadvantaged students access to a postsecondary education. The Pell Grant program has tried to keep up with…

  20. Physical Science Informatics: Providing Open Science Access to Microheater Array Boiling Experiment Data

    Science.gov (United States)

    McQuillen, John; Green, Robert D.; Henrie, Ben; Miller, Teresa; Chiaramonte, Fran

    2014-01-01

    The Physical Science Informatics (PSI) system is the next step in this an effort to make NASA sponsored flight data available to the scientific and engineering community, along with the general public. The experimental data, from six overall disciplines, Combustion Science, Fluid Physics, Complex Fluids, Fundamental Physics, and Materials Science, will present some unique challenges. Besides data in textual or numerical format, large portions of both the raw and analyzed data for many of these experiments are digital images and video, requiring large data storage requirements. In addition, the accessible data will include experiment design and engineering data (including applicable drawings), any analytical or numerical models, publications, reports, and patents, and any commercial products developed as a result of the research. This objective of paper includes the following: Present the preliminary layout (Figure 2) of MABE data within the PSI database. Obtain feedback on the layout. Present the procedure to obtain access to this database.

  1. Open Access to the Belgian Nuclear higher Education Network

    International Nuclear Information System (INIS)

    Simons, S.

    2005-01-01

    Under the name of the Belgian Nuclear higher Education Network, five Belgian universities, Universite Catholique de Louvain, Universiteit Gent, Universite de Liege, Vrije Universiteit Brussel have established in 2002, in collaboration with the Belgian Nuclear Research Centre SCK-CEN, a common Belgian Interuniversity Programme of the third cycle leading to the academic degree of Master of Science in Nuclear Engineering. Under the lead of the SCK-CEN a project to use and share the acquired experience of the Consortium BNEN - in order to support the realization of a common European Education Programme in Nuclear Engineering - has been accepted by the European Commission for funding under the EU's Sixth Research Framework Programme.The project wants to contribute actively to the development of a more harmonised approach for education in nuclear sciences and engineering in Europe. It brings the European higher Education Area closer to realization and helps to safeguard the necessary competence and expertise for the continued safe use of nuclear energy and other uses of radiation in industry and medicine in Europe. The project foresees input and participation from stakeholders from different countries of the enlarged European Union (EU-25) and will therefore contribute to the integration of the new member states into the European Research Area and thus to the enlargement of Europe. The set-up of the project foresees an active role for female experts with the intention to reinforce the place and role of women in science

  2. Coordinated Scheduling and Power Control in Cloud-Radio Access Networks

    KAUST Repository

    Douik, Ahmed; Dahrouj, Hayssam; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2015-01-01

    This paper addresses the joint coordinated scheduling and power control problem in cloud-enabled networks. Consider the downlink of a cloud-radio access network (CRAN), where the cloud is only responsible for the scheduling policy, power control, and synchronization of the transmit frames across the single-antenna base-stations (BS). The transmit frame consists of several time/frequency blocks, called power-zones (PZ). The paper considers the problem of scheduling users to PZs and determining their power levels (PL), by maximizing the weighted sum-rate under the practical constraints that each user cannot be served by more than one base-station, but can be served by one or more power-zones within each base-station frame. The paper solves the problem using a graph theoretical approach by introducing the joint scheduling and power control graph formed by several clusters, where each is formed by a set of vertices, representing the possible association of users, BSs, and PLs for one specific PZ. The problem is, then, formulated as a maximumweight clique problem, in which the weight of each vertex is the sum of the benefits of the individual associations belonging to that vertex. Simulation results suggest that the proposed crosslayer scheme provides appreciable performance improvement as compared to schemes from recent literature.

  3. Coordinated Scheduling and Power Control in Cloud-Radio Access Networks

    KAUST Repository

    Douik, Ahmed

    2015-12-01

    This paper addresses the joint coordinated scheduling and power control problem in cloud-enabled networks. Consider the downlink of a cloud-radio access network (CRAN), where the cloud is only responsible for the scheduling policy, power control, and synchronization of the transmit frames across the single-antenna base-stations (BS). The transmit frame consists of several time/frequency blocks, called power-zones (PZ). The paper considers the problem of scheduling users to PZs and determining their power levels (PL), by maximizing the weighted sum-rate under the practical constraints that each user cannot be served by more than one base-station, but can be served by one or more power-zones within each base-station frame. The paper solves the problem using a graph theoretical approach by introducing the joint scheduling and power control graph formed by several clusters, where each is formed by a set of vertices, representing the possible association of users, BSs, and PLs for one specific PZ. The problem is, then, formulated as a maximumweight clique problem, in which the weight of each vertex is the sum of the benefits of the individual associations belonging to that vertex. Simulation results suggest that the proposed crosslayer scheme provides appreciable performance improvement as compared to schemes from recent literature.

  4. A scalable and continuous-upgradable optical wireless and wired convergent access network.

    Science.gov (United States)

    Sung, J Y; Cheng, K T; Chow, C W; Yeh, C H; Pan, C-L

    2014-06-02

    In this work, a scalable and continuous upgradable convergent optical access network is proposed. By using a multi-wavelength coherent comb source and a programmable waveshaper at the central office (CO), optical millimeter-wave (mm-wave) signals of different frequencies (from baseband to > 100 GHz) can be generated. Hence, it provides a scalable and continuous upgradable solution for end-user who needs 60 GHz wireless services now and > 100 GHz wireless services in the future. During the upgrade, user only needs to upgrade their optical networking unit (ONU). A programmable waveshaper is used to select the suitable optical tones with wavelength separation equals to the desired mm-wave frequency; while the CO remains intact. The centralized characteristics of the proposed system can easily add any new service and end-user. The centralized control of the wavelength makes the system more stable. Wired data rate of 17.45 Gb/s and w-band wireless data rate up to 3.36 Gb/s were demonstrated after transmission over 40 km of single-mode fiber (SMF).

  5. A ground-base Radar network to access the 3D structure of MLT winds

    Science.gov (United States)

    Stober, G.; Chau, J. L.; Wilhelm, S.; Jacobi, C.

    2016-12-01

    The mesosphere/lower thermosphere (MLT) is a highly variable atmospheric region driven by wave dynamics at various scales including planetary waves, tides and gravity waves. Some of these propagate through the MLT into the thermosphere/ionosphere carrying energy and momentum from the middle atmosphere into the upper atmosphere. To improve our understanding of the wave energetics and momentum transfer during their dissipation it is essential to characterize their space time properties. During the last two years we developed a new experimental approach to access the horizontal structure of wind fields at the MLT using a meteor radar network in Germany, which we called MMARIA - Multi-static Multi-frequency Agile Radar for Investigation of the Atmosphere. The network combines classical backscatter meteor radars and passive forward scatter radio links. We present our preliminary results using up to 7 different active and passive radio links to obtain horizontally resolved wind fields applying a statistical inverse method. The wind fields are retrieved with 15-30 minutes temporal resolution on a grid with 30x30 km horizontal spacing. Depending on the number of observed meteors, we are able to apply the wind field inversion at heights between 84-94 km. The horizontally resolved wind fields provide insights of the typical horizontal gravity wave length and the energy cascade from large scales to small scales. We present first power spectra indicating the transition from the synoptic wave scale to the gravity wave scale.

  6. ONU power saving modes in next generation optical access networks: progress, efficiency and challenges.

    Science.gov (United States)

    Dixit, Abhishek; Lannoo, Bart; Colle, Didier; Pickavet, Mario; Demeester, Piet

    2012-12-10

    The optical network unit (ONU), installed at a customer's premises, accounts for about 60% of power in current fiber-to-the-home (FTTH) networks. We propose a power consumption model for the ONU and evaluate the ONU power consumption in various next generation optical access (NGOA) architectures. Further, we study the impact of the power savings of the ONU in various low power modes such as power shedding, doze and sleep.

  7. Nonadditivity of quantum capacities of quantum multiple-access channels and the butterfly network

    International Nuclear Information System (INIS)

    Huang Peng; He Guangqiang; Zhu Jun; Zeng Guihua

    2011-01-01

    Multipartite quantum information transmission without additional classical resources is investigated. We show purely quantum superadditivity of quantum capacity regions of quantum memoryless multiple-access (MA) channels, which are not entanglement breaking. Also, we find that the superadditivity holds when the MA channel extends to the quantum butterfly network, which can achieve quantum network coding. The present widespread effects for the channels which enable entanglement distribution have not been revealed for multipartite scenarios.

  8. Energy-Efficient Boarder Node Medium Access Control Protocol for Wireless Sensor Networks

    OpenAIRE

    Razaque, Abdul; Elleithy, Khaled M.

    2014-01-01

    This paper introduces the design, implementation, and performance analysis of the scalable and mobility-aware hybrid protocol named boarder node medium access control (BN-MAC) for wireless sensor networks (WSNs), which leverages the characteristics of scheduled and contention-based MAC protocols. Like contention-based MAC protocols, BN-MAC achieves high channel utilization, network adaptability under heavy traffic and mobility, and low latency and overhead. Like schedule-based MAC protocols,...

  9. Adaptive Code Division Multiple Access Protocol for Wireless Network-on-Chip Architectures

    Science.gov (United States)

    Vijayakumaran, Vineeth

    Massive levels of integration following Moore's Law ushered in a paradigm shift in the way on-chip interconnections were designed. With higher and higher number of cores on the same die traditional bus based interconnections are no longer a scalable communication infrastructure. On-chip networks were proposed enabled a scalable plug-and-play mechanism for interconnecting hundreds of cores on the same chip. Wired interconnects between the cores in a traditional Network-on-Chip (NoC) system, becomes a bottleneck with increase in the number of cores thereby increasing the latency and energy to transmit signals over them. Hence, there has been many alternative emerging interconnect technologies proposed, namely, 3D, photonic and multi-band RF interconnects. Although they provide better connectivity, higher speed and higher bandwidth compared to wired interconnects; they also face challenges with heat dissipation and manufacturing difficulties. On-chip wireless interconnects is one other alternative proposed which doesn't need physical interconnection layout as data travels over the wireless medium. They are integrated into a hybrid NOC architecture consisting of both wired and wireless links, which provides higher bandwidth, lower latency, lesser area overhead and reduced energy dissipation in communication. However, as the bandwidth of the wireless channels is limited, an efficient media access control (MAC) scheme is required to enhance the utilization of the available bandwidth. This thesis proposes using a multiple access mechanism such as Code Division Multiple Access (CDMA) to enable multiple transmitter-receiver pairs to send data over the wireless channel simultaneously. It will be shown that such a hybrid wireless NoC with an efficient CDMA based MAC protocol can significantly increase the performance of the system while lowering the energy dissipation in data transfer. In this work it is shown that the wireless NoC with the proposed CDMA based MAC protocol

  10. The NASA Regional Planetary Image Facility (RPIF) Network: A Key Resource for Accessing and Using Planetary Spatial Data

    Science.gov (United States)

    Hagerty, J. J.

    2017-12-01

    The role of the NASA Regional Planetary Image Facility (RPIF) Network is evolving as new science-ready spatial data products continue to be created and as key historical planetary data sets are digitized. Specifically, the RPIF Network is poised to serve specialized knowledge and services in a user-friendly manner that removes most barriers to locating, accessing, and exploiting planetary spatial data, thus providing a critical data access role within a spatial data infrastructure. The goal of the Network is to provide support and training to a broad audience of planetary spatial data users. In an effort to meet the planetary science community's evolving needs, we are focusing on the following objectives: Maintain and improve the delivery of historical data accumulated over the past four decades so as not to lose critical, historical information. This is being achieved by systematically digitizing fragile materials, allowing increased access and preserving them at the same time. Help users locate, access, visualize, and exploit planetary science data. Many of the facilities have begun to establish Guest User Facilities that allow researchers to use and/or be trained on GIS equipment and other specialized tools like Socet Set/GXP photogrammetry workstations for generating digital elevation maps. Improve the connection between the Network nodes while also leveraging the unique resources of each node. To achieve this goal, each facility is developing and sharing searchable databases of their collections, including robust metadata in a standards compliant way. Communicate more effectively and regularly with the planetary science community in an effort to make potential users aware of resources and services provided by the Network, while also engaging community members in discussions about community needs. Provide a regional resource for the science community, colleges, universities, museums, media, and the public to access planetary data. Introduce new strategies for

  11. Future Scenarios for Software-Defined Metro and Access Networks and Software-Defined Photonics

    Directory of Open Access Journals (Sweden)

    Tommaso Muciaccia

    2017-01-01

    Full Text Available In recent years, architectures, devices, and components in telecommunication networks have been challenged by evolutionary and revolutionary factors which are drastically changing the traffic features. Most of these changes imply the need for major re-configurability and programmability not only in data-centers and core networks, but also in the metro-access segment. In a wide variety of contexts, this necessity has been addressed by the proposed introduction of the innovative paradigm of software-defined networks (SDNs. Several solutions inspired by the SDN model have been recently proposed also for metro and access networks, where the adoption of a new generation of software-defined reconfigurable integrated photonic devices is highly desirable. In this paper, we review the possible future application scenarios for software-defined metro and access networks and software-defined photonics (SDP, on the base of analytics, statistics, and surveys. This work describes the reasons underpinning the presented radical change of paradigm and summarizes the most significant solutions proposed in literature, with a specific emphasis to physical-layer reconfigurable networks and a focus on both architectures and devices.

  12. Service Class Resource Management For Green Wireless-Optical Broadband Access NetworksWOBAN

    Directory of Open Access Journals (Sweden)

    SRUTHY.S

    2015-08-01

    Full Text Available Abstract-Broadband access networks have become an essential part of worldwide communication systems because of the exponential growth of broadband services such as video on demand high definition TV internet protocol TV and video conferencing. Exponential growth in the volume of wireless data boosted by the growing popularity of mobile devices such as smartphone and tablets has forced the telecommunication industries to rethink the way networks are currently designed and to focus on the development of high-capacity mobile broadband networks. In response to this challenge researchers have been working toward the development of an integrated wireless optical broadband access network. Two major candidate technologies which are currently known for their high capacity as well as quality of service QoS for multimedia traffic are passive optical networks PON and fourth generation 4G wireless networks. PON is a wired access technology well known for its cost efficiency and high capacity whereas 4G is a wireless broadband access technology which has achieved broad market acceptance because of its ease of deployment ability to offer mobility and its cost efficiency. Integration of PON and 4G technologies in the form of wireless-optical broadband access networks offers advantages such as extension of networks in rural areas support for mobile broadband services and quick deployment of broadband networks. These two technologies however have different design architectures for handling broadband services that require quality of service. For example 4G networks use traffic classification for supporting different QoS demands whereas the PON architecture has no such mechanism to differentiate between types of traffic. These two technologies also differ in their power saving mechanisms. Propose a service class mapping for the integrated PON-4G network which is based on the MG1 queuing model and class-based power saving mechanism which significantly improves the

  13. Open access and network services -- A global approach

    International Nuclear Information System (INIS)

    Cook, A.S.; Merrill, H.M.

    1995-01-01

    Utilities functioning in a competitive electricity market are required to provide unbundled services. This paper describes how to make unbundled transmission services available in a competitive electricity market. Methods are presented for developing the long-run marginal cost of transmission and for pricing stand-by and top-up electricity supply. The methods are illustrated with case studies based on current data

  14. Unifying Water Data Sources: How the CUAHSI Water Data Center is Enabling and Improving Access to a Growing Catalog of over 100 Data Providers

    Science.gov (United States)

    Pollak, J.; Berry, K.; Couch, A.; Arrigo, J.; Hooper, R. P.

    2013-12-01

    Scientific data about water are collected and distributed by numerous sources which can differ tremendously in scale. As competition for water resources increases, increasing access to and understanding of information about water will be critical. The mission of the new CUAHSI Water Data Center (WDC) is to provide those researchers who collect data a medium to publish their datasets and give those wanting to discover data the proper tools to efficiently find the data that they seek. These tools include standards-based data publication, data discovery tools based upon faceted and telescoping search, and a data analysis tool HydroDesktop that downloads and unifies data in standardized formats. The CUAHSI Hydrologic Information System (HIS) is a community developed and open source system for sharing water data. As a federated, web service oriented system it enables data publication for a diverse user population including scientific investigators (Research Coordination Networks, Critical Zone Observatories), government agencies (USGS, NASA, EPA), and citizen scientists (watershed associations). HydroDesktop is an end user application for data consumption in this system that the WDC supports. This application can be used for finding, downloading, and analyzing data from the HIS. It provides a GIS interface that allows users to incorporate spatial data that are not accessible via HIS, simple analysis tools to facilitate graphing and visualization, tools to export data to common file types, and provides an extensible architecture that developers can build upon. HydroDesktop, however, is just one example of a data access client for HIS. The web service oriented architecture enables data access by an unlimited number of clients provided they can consume the web services used in HIS. One such example developed at the WDC is the 'Faceted Search Client', which capitalizes upon exploratory search concepts to improve accuracy and precision during search. We highlight such

  15. A Fine-Grained Data Access Control System in Wireless Sensor Network

    Directory of Open Access Journals (Sweden)

    Boniface K. Alese

    2015-12-01

    Full Text Available The evolving realities of Wireless Sensor Network (WSN deployed to various terrain of life require serving multiple applications. As large amount of sensed data are distributed and stored in individual sensors nodes, the illegal access to these sensitive data can be devastating. Consequently, data insecurity becomes a big concern. This study, therefore, proposes a fine-grained access control system which only requires the right set of users to access a particular data, based on their access privileges in the sensor networks. It is designed using Priccess Protocol with Access policy formulation adopting the principle of Bell Lapadula model as well as Attribute-Based Encryption (ABE to control access to sensor data. The functionality of the proposed system is simulated using Netbeans. The performance analysis of the proposed system using execution time and size of the key show that the higher the key size, the harder it becomes for the attacker to hack the system. Additionally, the time taken for the proposed work is lesser which makes the work faster than the existing work. Consequently, a well secure interactive web-based application that could facilitates the field officers access to stored data in safe and secure manner is developed.

  16. Is Access to Outpatient Neurosurgery Affected by Narrow Insurance Networks? Results From Statewide Analysis of Marketplace Plans in Louisiana.

    Science.gov (United States)

    Dossani, Rimal H; Kalakoti, Piyush; Nanda, Anil; Guthikonda, Bharat; Tumialán, Luis M

    2018-02-06

    The main objective of the Affordable Care Act (ACA) was to make health insurance affordable to all Americans while addressing the lack of coverage for 48 million people. In the face of rapidly increasing enrollment and rising demand for inexpensive plans, insurance providers are limiting in-network physicians. Provider networks offering plans with limited in-network physicians have become known as "narrow networks." To assesses the adequacy of ACA marketplace plans for outpatient neurosurgery in Louisiana. The Marketplace Public Use Files were searched for all "silver" plans. A total of 7 silver plans were identified in Louisiana. Using the plans' online directories, a search of in-network neurosurgeons in Louisiana parishes with >100 000 population was performed. The primary outcome was lack of in-network neurosurgeon(s) in silver plans within 50 miles of selected zip code for each parish with >100 000 population. Plans without in-network neurosurgeon(s) are labeled as neurosurgeon-deficient plans. Several plans in Louisiana are neurosurgeon deficient, ie no in-network neurosurgeon within 50 miles of the designated parish zip code. Company A's plan 3 is deficient in all 5 parishes, while company C and company D silver plans are deficient in 4 out of 14 (29%). Combined results from all counties and plans demonstrate that 43% (3 out of 7) of all silver plans in Louisiana are neurosurgeon deficient in at least 4 parishes with population >100 000. In Louisiana, narrow networks have limited access to neurosurgical care for those patients with ACA silver plans. Copyright © 2018 by the Congress of Neurological Surgeons

  17. Multigigabit W-Band (75–110 GHz) Bidirectional Hybrid Fiber-Wireless Systems in Access Networks

    DEFF Research Database (Denmark)

    Pang, Xiaodan; Lebedev, Alexander; Vegas Olmos, Juan José

    2014-01-01

    compare the transmission performances in terms of achievable wireless distances with and without using a high-frequency electrical power amplifier at the wireless transmitter. A downlink 16-Gbit/s QPSK signal and an uplink 1.25-Gbit/s ASK signal transmission over the two implementations are experimentally......We experimentally demonstrate multigigabit capacity bidirectional hybrid fiber-wireless systems with RF carrier frequencies at the W-band (75-110 GHz) that enables the seamless convergence between wireless and fiber-optic data transmission systems in access networks. In this study, we evaluate...... the transmission performances in two scenarios: a fiber-wireless access link that directly provide high-speed connections to wireless end users, and a fiber-wireless-fiber signal relay where a high capacity wireless link can be used to bridge two access fiber spans over physical obstacles. In both scenarios, we...

  18. Highlights and Opportunities from Continuous Access to Gas Hydrates Sites at Ocean Networks Canada's NEPTUNE Observatory

    Science.gov (United States)

    Scherwath, M.; Heesemann, M.; Riedel, M.; Thomsen, L.; Roemer, M.; Chatzievangelou, D.; Purser, A.

    2017-12-01

    Since 2009 Ocean Networks Canada provides permanent access and continuous data in near real-time from two prominent gas hydrates research sites at the Northern Cascadia Margin, Barkley Canyon and Clayoquot Slope off Vancouver Island, through power and communication cables directly from shore. We show data highlights from the seafloor crawler Wally, the world's first internet operated vehicle, in a field of hydrate mounds and outcropping gas hydrates, and its co-located sonars and state-of-the-ocean sensors and Barkley Canyon. For example, spectacular views from the benthic communities and their changes over time are captured by video. At Clayoquot Slope highly active gas seep fields are monitored with a rotating multibeam sonar and various other environmental sensors. In addition, newly installed geodetic sensors as well as an instrumented borehole in that area are now online and provide additional data on subduction-related deformation and potential links to gas discharge. These show-case examples highlight the benefits of co-located experiments that enable interdisciplinary research and also the ability for high-power and -bandwidth long-term monitoring at remote seafloor locations, that over time will provide baselines for environmental monitoring together with natural variability and potential long-term trends.

  19. Advance reservation access control using software-defined networking and tokens

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Joaquin; Jung, Eun-Sung; Kettimuthu, Rajkumar; Rao, Nageswara S. V.; Foster, Ian T.; Clark, Russ; Owen, Henry

    2018-02-01

    Advance reservation systems allow users to reserve dedicated bandwidth connection resources from advanced high-speed networks. A common use case for such systems is data transfers in distributed science environments in which a user wants exclusive access to the reservation. However, current advance network reservation methods cannot ensure exclusive access of a network reservation to the specific flow for which the user made the reservation. We present here a novel network architecture that addresses this limitation and ensures that a reservation is used only by the intended flow. We achieve this by leveraging software-defined networking (SDN) and token-based authorization. We use SDN to orchestrate and automate the reservation of networking resources, end-to-end and across multiple administrative domains, and tokens to create a strong binding between the user or application that requested the reservation and the flows provisioned by SDN. We conducted experiments on the ESNet 100G SDN testbed, and demonstrated that our system effectively protects authorized flows from competing traffic in the network. (C) 2017 Elsevier B.V. All rights reserved.

  20. 47 CFR 51.329 - Notice of network changes: Methods for providing notice.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Notice of network changes: Methods for providing notice. 51.329 Section 51.329 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...) Filing a public notice with the Commission; or (2) Providing public notice through industry fora...

  1. On-demand virtual optical network access using 100 Gb/s Ethernet.

    Science.gov (United States)

    Ishida, Osamu; Takamichi, Toru; Arai, Sachine; Kawate, Ryusuke; Toyoda, Hidehiro; Morita, Itsuro; Araki, Soichiro; Ichikawa, Toshiyuki; Hoshida, Takeshi; Murai, Hitoshi

    2011-12-12

    Our Terabit LAN initiatives attempt to enhance the scalability and utilization of lambda resources. This paper describes bandwidth-on-demand virtualized 100GE access to WDM networks on a field fiber test-bed using multi-domain optical-path provisioning. © 2011 Optical Society of America

  2. A three-stage heuristic for harvest scheduling with access road network development

    Science.gov (United States)

    Mark M. Clark; Russell D. Meller; Timothy P. McDonald

    2000-01-01

    In this article we present a new model for the scheduling of forest harvesting with spatial and temporal constraints. Our approach is unique in that we incorporate access road network development into the harvest scheduling selection process. Due to the difficulty of solving the problem optimally, we develop a heuristic that consists of a solution construction stage...

  3. Receiver-initiated medium access control protocols for wireless sensor networks

    DEFF Research Database (Denmark)

    Fafoutis, Xenofon; Di Mauro, Alessio; Vithanage, Madava D.

    2015-01-01

    One of the fundamental building blocks of a Wireless Sensor Network (WSN) is the Medium Access Control (MAC) protocol, that part of the system governing when and how two independent neighboring nodes activate their respective transceivers to directly interact. Historically, data exchange has always...

  4. A hybrid medium access control for convergence of broadband wireless and wireline ATM networks

    DEFF Research Database (Denmark)

    Liu, Hong; Gliese, Ulrik Bo; Dittmann, Lars

    2000-01-01

    In this paper, we propose a hybrid medium access control protocol for supporting broadband integrated services in the wireless ATM networks. The integrated services include CBR, VBR and ABR traffic varying from low bit-rate to very high bit-rate. The proposed protocol is an excellent compromise...

  5. Dynamic optical fiber delivery of Ka-band packet transmissions for wireless access networks

    DEFF Research Database (Denmark)

    Rodríguez Páez, Juan Sebastián; Madsen, Peter; Tafur Monroy, Idelfonso

    2017-01-01

    A Reconfigurable Radio Access Unit is presented and experimentally demonstrated. In the unit, an optical switching system is set to dynamically deliver different packets to different points in the network. The packets are transmitted wirelesslty on the Ka-band (26–40 GHz), achieving BER values...

  6. A Novel Medium Access Control for Ad hoc Networks Based on OFDM System

    Institute of Scientific and Technical Information of China (English)

    YU Yi-fan; YIN Chang-chuan; YUE Guang-xin

    2005-01-01

    Recently, hosts of Medium Access Control (MAC) protocols for Ad hoc radio networks have been proposed to solve the hidden terminal problem and exposed terminal problem. However most of them take into no account the interactions between physical (PHY) system and MAC protocol. Therefore, the current MAC protocols are either inefficient in the networks with mobile nodes and fading channel or difficult in hardware implementation. In this paper, we present a novel media access control for Ad hoc networks that integrates a media access control protocol termed as Dual Busy Tone Multiple Access (DBTMA) into Orthogonal Frequency Division Multiplexing (OFDM) system proposed in IEEE 802.11a standard. The analysis presented in the paper indicates that the proposed MAC scheme achieves performance improvement over IEEE 802.11 protocol about 25%~80% especially in the environment with high mobility and deep fading. The complexity of the proposed scheme is also lower than other implementation of similar busy tone solution. Furthermore, it is compatible with IEEE 802.11a networks.

  7. Assessing Individual Social Capital Capacity: The Development and Validation of a Network Accessibility Scale

    Science.gov (United States)

    Hatala, John-Paul

    2009-01-01

    Any organization that is able to promote the importance of increased levels of social capital and individuals who can leverage and use the resources that exist within the network may experience higher levels of performance. This study sought to add to our knowledge about individuals' accessing social resources for the purpose of accomplishing…

  8. Knowledge-Based Multiple Access Protocol in Broadband Wireless ATM Networks

    DEFF Research Database (Denmark)

    Liu, Hong; Gliese, Ulrik Bo; Dittmann, Lars

    1999-01-01

    In this paper, we propose a knowledge-based multiple access protocol for the extension of wireline ATM to wireless networks. The objective is to enable effecient transmission of all kinds of ATM traffic in the wireless channel with guaranteed QoS.The proposed protocol utilixes knowledge of the main...... guaranteed QoS requirements to a variety of ATM applications....

  9. Analysis of the Decoupled Access for Downlink and Uplink in Wireless Heterogeneous Networks

    DEFF Research Database (Denmark)

    Smiljkovikj, K.; Popovski, Petar; Gavrilovska, L.

    2015-01-01

    Wireless cellular networks evolve towards a heterogeneous infrastructure, featuring multiple types of Base Stations (BSs), such as Femto BSs (FBSs) and Macro BSs (MBSs). A wireless device observes multiple points (BSs) through which it can access the infrastructure and it may choose to receive th...

  10. Data Archiving and Networked Services (DANS) promotes sustained access to digital research data

    NARCIS (Netherlands)

    van Berchum, M.; Kraaikamp, Emilie

    2015-01-01

    Data Archiving and Networked Services (DANS) promotes sustained access to digital research data. For this purpose, DANS encourages researchers to archive and reuse data in a sustained form. In the online archiving system EASY research data is stored in a permanent and sustainable manner, according

  11. Scalable Active Optical Access Network Using Variable High-Speed PLZT Optical Switch/Splitter

    Science.gov (United States)

    Ashizawa, Kunitaka; Sato, Takehiro; Tokuhashi, Kazumasa; Ishii, Daisuke; Okamoto, Satoru; Yamanaka, Naoaki; Oki, Eiji

    This paper proposes a scalable active optical access network using high-speed Plumbum Lanthanum Zirconate Titanate (PLZT) optical switch/splitter. The Active Optical Network, called ActiON, using PLZT switching technology has been presented to increase the number of subscribers and the maximum transmission distance, compared to the Passive Optical Network (PON). ActiON supports the multicast slot allocation realized by running the PLZT switch elements in the splitter mode, which forces the switch to behave as an optical splitter. However, the previous ActiON creates a tradeoff between the network scalability and the power loss experienced by the optical signal to each user. It does not use the optical power efficiently because the optical power is simply divided into 0.5 to 0.5 without considering transmission distance from OLT to each ONU. The proposed network adopts PLZT switch elements in the variable splitter mode, which controls the split ratio of the optical power considering the transmission distance from OLT to each ONU, in addition to PLZT switch elements in existing two modes, the switching mode and the splitter mode. The proposed network introduces the flexible multicast slot allocation according to the transmission distance from OLT to each user and the number of required users using three modes, while keeping the advantages of ActiON, which are to support scalable and secure access services. Numerical results show that the proposed network dramatically reduces the required number of slots and supports high bandwidth efficiency services and extends the coverage of access network, compared to the previous ActiON, and the required computation time for selecting multicast users is less than 30msec, which is acceptable for on-demand broadcast services.

  12. The IRIS Education and Outreach Program: Providing access to data and equipment for educational and public use

    Science.gov (United States)

    Taber, J.; Toigo, M.; Bravo, T. K.; Hubenthal, M.; McQuillan, P. J.; Welti, R.

    2009-12-01

    The IRIS Education and Outreach Program has been an integral part of IRIS for the past 10 years and during that time has worked to advance awareness and understanding of seismology and earth science while inspiring careers in geophysics. The focus on seismology and the use of seismic data has allowed the IRIS E&O program to develop and disseminate a unique suite of products and services for a wide range of audiences. One result of that effort has been increased access to the IRIS Data Management System by non-specialist audiences and simplified use of location and waveform data. The Seismic Monitor was one of the first Web-based tools for observing near-real-time seismicity. It continues to be the most popular IRIS web page, and thus it presents aspects of seismology to a very wide audience. For individuals interested in more detailed ground motion information, waveforms can be easily viewed using the Rapid Earthquake Viewer, developed by the University of South Carolina in collaboration with IRIS E&O. The Seismographs in Schools program gives schools the opportunity to apply for a low-cost educational seismograph and to receive training for its use in the classroom. To provide better service to the community, a new Seismographs in Schools website was developed in the past year with enhanced functions to help teachers improve their teaching of seismology. The site encourages schools to make use of seismic data and communicate with other educational seismology users throughout the world. Users can view near-real-time displays of other participating schools, upload and download data, and use the “find a teacher” tool to contact nearby schools that also may be operating seismographs. In order to promote and maintain program participation and communication, the site features a discussion forum to encourage and support the growing global community of educational seismograph users. Any data that is submitted to the Seismographs in Schools Website is also accessible

  13. Revisiting the picture-superiority effect in symbolic comparisons: do pictures provide privileged access?

    Science.gov (United States)

    Amrhein, Paul C; McDaniel, Mark A; Waddill, Paula

    2002-09-01

    In 4 experiments, symbolic comparisons were investigated to test semantic-memory retrieval accounts espousing processing advantages for picture over word stimuli. In Experiment 1, participants judged pairs of animal names or pictures by responding to questions probing concrete or abstract attributes (texture or size, ferocity or intelligence). Per pair, attributes were salient or nonsalient concerning their prerated relevance to animals being compared. Distance (near or far) between attribute magnitudes was also varied. Pictures did not significantly speed responding relative to words across all other variables. Advantages were found forfar attribute magnitudes (i.e., the distance effect) and salient attributes. The distance effect was much less for salient than nonsalient concrete-attribute comparisons. These results were consistently found in additional experiments with increased statistical power to detect modality effects. Our findings argue against dual-coding and some common-code accounts of conceptual attribute processing, urging reexamination of the assumption that pictures confer privileged access to long-term knowledge.

  14. Free access to INIS database provides a gateway to nuclear energy research results

    International Nuclear Information System (INIS)

    Tolonen, E.; Malmgren, M.

    2009-01-01

    Free access to INIS database was opened to all the Internet users around the world on May, 2009. The article reviews the history of INIS (the International Nuclear Information System), data aquisition process, database content and search possibilities. INIS is focused on the worldwide literature of the peaceful uses of nuclear energy and the database is produced in close collaboration with the IEA/ETDE World Energy Base (ETDEWEB), a database focusing on all aspects of energy. Nuclear Science Abstracts database (NSA), which is a comprehensive collection of international nuclear science and technology literature for the period 1948 through 1976, is also briefly discussed in the article. In Finland, the recently formed Aalto University is responsible for collecting and disseminating information (literature) and for the preparation of input to the INIS and IEA/ETDE Databases on the national level

  15. Gain transient control for wavelength division multiplexed access networks using semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Gibbon, Timothy Braidwood; Osadchiy, Alexey Vladimirovich; Kjær, Rasmus

    2009-01-01

    Gain transients can severely hamper the upstream network performance in wavelength division multiplexed (WDM) access networks featuring erbium doped fiber amplifiers (EDFAs) or Raman amplification. We experimentally demonstrate for the first time using 10 Gb/s fiber transmission bit error rate...... measurements how a near-saturated semiconductor optical amplifier (SOA) can be used to control these gain transients. An SOA is shown to reduce the penalty of transients originating in an EDFA from 2.3 dB to 0.2 dB for 10 Gb/s transmission over standard single mode fiber using a 231-1 PRBS pattern. The results...... suggest that a single SOA integrated within a WDM receiver at the metro node could offer a convenient all-optical solution for upstream transient controlin WDM access networks....

  16. Bandwidth Impacts of Localizing Peer-to-Peer IP Video Traffic in Access and Aggregation Networks

    Directory of Open Access Journals (Sweden)

    Kerpez Kenneth

    2008-01-01

    Full Text Available Abstract This paper examines the burgeoning impact of peer-to-peer (P2P traffic IP video traffic. High-quality IPTV or Internet TV has high-bandwidth requirements, and P2P IP video could severely strain broadband networks. A model for the popularity of video titles is given, showing that some titles are very popular and will often be available locally; making localized P2P attractive for video titles. The bandwidth impacts of localizing P2P video to try and keep traffic within a broadband access network area or within a broadband access aggregation network area are examined. Results indicate that such highly localized P2P video can greatly lower core bandwidth usage.

  17. Bandwidth Impacts of Localizing Peer-to-Peer IP Video Traffic in Access and Aggregation Networks

    Directory of Open Access Journals (Sweden)

    Kenneth Kerpez

    2008-10-01

    Full Text Available This paper examines the burgeoning impact of peer-to-peer (P2P traffic IP video traffic. High-quality IPTV or Internet TV has high-bandwidth requirements, and P2P IP video could severely strain broadband networks. A model for the popularity of video titles is given, showing that some titles are very popular and will often be available locally; making localized P2P attractive for video titles. The bandwidth impacts of localizing P2P video to try and keep traffic within a broadband access network area or within a broadband access aggregation network area are examined. Results indicate that such highly localized P2P video can greatly lower core bandwidth usage.

  18. Women's Access and Provider Practices for the Case Management of Malaria during Pregnancy: A Systematic Review and Meta-Analysis

    NARCIS (Netherlands)

    Hill, Jenny; D'Mello-Guyett, Lauren; Hoyt, Jenna; van Eijk, Anna M.; ter Kuile, Feiko O.; Webster, Jayne

    2014-01-01

    Background: WHO recommends prompt diagnosis and quinine plus clindamycin for treatment of uncomplicated malaria in the first trimester and artemisinin-based combination therapies in subsequent trimesters. We undertook a systematic review of women's access to and healthcare provider adherence to WHO

  19. 42 CFR 433.127 - Termination of FFP for failure to provide access to claims processing and information retrieval...

    Science.gov (United States)

    2010-10-01

    ... claims processing and information retrieval systems. 433.127 Section 433.127 Public Health CENTERS FOR... PROGRAMS STATE FISCAL ADMINISTRATION Mechanized Claims Processing and Information Retrieval Systems § 433.127 Termination of FFP for failure to provide access to claims processing and information retrieval...

  20. The Role of the Social Network in Access to Psychosocial Services for Migrant Elderly-A Qualitative Study.

    Science.gov (United States)

    Schoenmakers, Daphne; Lamkaddem, Majda; Suurmond, Jeanine

    2017-10-11

    Abstract : Background: Despite high prevalence of mental problems among elderly migrants in The Netherlands, the use of psychosocial care services by this group is low. Scientific evidence points at the crucial role of social support for mental health and the use of psychosocial services. We therefore explored the role of social networks in the access to psychosocial care among elderly migrants in The Netherlands. Methods: A qualitative study was conducted using semi-structured group interviews and individual interviews. The eight group and eleven individual interviews (respectively n = 58 and n = 11) were conducted in The Netherlands with Turkish, Moroccan, Surinamese, and Dutch elderly. The data were analysed through coding and comparing fragments and recognizing patterns. Results: Support of the social network is important to navigate to psychosocial care and is most frequently provided by children. However, the social network of elderly migrants is generally not able to meet the needs of the elderly. This is mostly due to poor mental health literacy of the social network, taboo, and stigma around mental illness and the busy lives of the social network members. Conclusion s : Strategies to address help-seeking barriers should consider mental health literacy in elderly migrants as well as their social networks, and counteract taboos and stigma of mental health problems.

  1. The Role of the Social Network in Access to Psychosocial Services for Migrant Elderly—A Qualitative Study

    Directory of Open Access Journals (Sweden)

    Daphne Schoenmakers

    2017-10-01

    Full Text Available Abstract: Background: Despite high prevalence of mental problems among elderly migrants in The Netherlands, the use of psychosocial care services by this group is low. Scientific evidence points at the crucial role of social support for mental health and the use of psychosocial services. We therefore explored the role of social networks in the access to psychosocial care among elderly migrants in The Netherlands. Methods: A qualitative study was conducted using semi-structured group interviews and individual interviews. The eight group and eleven individual interviews (respectively n = 58 and n = 11 were conducted in The Netherlands with Turkish, Moroccan, Surinamese, and Dutch elderly. The data were analysed through coding and comparing fragments and recognizing patterns. Results: Support of the social network is important to navigate to psychosocial care and is most frequently provided by children. However, the social network of elderly migrants is generally not able to meet the needs of the elderly. This is mostly due to poor mental health literacy of the social network, taboo, and stigma around mental illness and the busy lives of the social network members. Conclusions: Strategies to address help-seeking barriers should consider mental health literacy in elderly migrants as well as their social networks, and counteract taboos and stigma of mental health problems.

  2. Open-Access-Kooperationen in Österreich: Open Access Network Austria und E-Infrastructures Austria – aktuelle Entwicklungen seit 2012

    Directory of Open Access Journals (Sweden)

    Bauer, Bruno

    2014-12-01

    Full Text Available [english] The Berlin Declaration on Open Access to scientific knowledge was published in October 2003. All over the world initiatives and projects were started. However, in Austria Open Access got little attention over many years. This was confirmed by a study among Austrian universities on behalf of the Council of Austrian University Libraries. Finally at the turn of the year 2012/2013 the Open Access Network Austria and the university infrastructure project E-Infrastructure Austria were started to push Open Access in Austria on a national level. So 10 years after the Berlin Declaration Austria set up the preconditions to establish sustainable Open Access.

  3. Hybrid Scheduling/Signal-Level Coordination in the Downlink of Multi-Cloud Radio-Access Networks

    KAUST Repository

    Douik, Ahmed

    2016-03-28

    In the context of resource allocation in cloud- radio access networks, recent studies assume either signal-level or scheduling-level coordination. This paper, instead, considers a hybrid level of coordination for the scheduling problem in the downlink of a multi-cloud radio- access network, so as to benefit from both scheduling policies. Consider a multi-cloud radio access network, where each cloud is connected to several base-stations (BSs) via high capacity links, and therefore allows joint signal processing between them. Across the multiple clouds, however, only scheduling-level coordination is permitted, as it requires a lower level of backhaul communication. The frame structure of every BS is composed of various time/frequency blocks, called power- zones (PZs), and kept at fixed power level. The paper addresses the problem of maximizing a network-wide utility by associating users to clouds and scheduling them to the PZs, under the practical constraints that each user is scheduled, at most, to a single cloud, but possibly to many BSs within the cloud, and can be served by one or more distinct PZs within the BSs\\' frame. The paper solves the problem using graph theory techniques by constructing the conflict graph. The scheduling problem is, then, shown to be equivalent to a maximum- weight independent set problem in the constructed graph, in which each vertex symbolizes an association of cloud, user, BS and PZ, with a weight representing the utility of that association. Simulation results suggest that the proposed hybrid scheduling strategy provides appreciable gain as compared to the scheduling-level coordinated networks, with a negligible degradation to signal-level coordination.

  4. On designing of a low leakage patient-centric provider network.

    Science.gov (United States)

    Zheng, Yuchen; Lin, Kun; White, Thomas; Pickreign, Jeremy; Yuen-Reed, Gigi

    2018-03-27

    When a patient in a provider network seeks services outside of their community, the community experiences a leakage. Leakage is undesirable as it typically leads to higher out-of-network cost for patient and increases barrier for care coordination, which is particularly problematic for Accountable Care Organization (ACO) as the in-network providers are financially responsible for quality of care and outcome. We aim to design a data-driven method to identify naturally occurring provider networks driven by diabetic patient choices, and understand the relationship among provider composition, patient composition, and service leakage pattern. By doing so, we learn the features of low service leakage provider networks that can be generalized to different patient population. Data used for this study include de-identified healthcare insurance administrative data acquired from Capital District Physicians' Health Plan (CDPHP) for diabetic patients who resided in four New York state counties (Albany, Rensselaer, Saratoga, and Schenectady) in 2014. We construct a healthcare provider network based on patients' historical medical insurance claims. A community detection algorithm is used to identify naturally occurring communities of collaborating providers. For each detected community, a profile is built using several new key measures to elucidate stakeholders of our findings. Finally, import-export analysis is conducted to benchmark their leakage pattern and identify further leakage reduction opportunity. The design yields six major provider communities with diverse profiles. Some communities are geographically concentrated, while others tend to draw patients with certain diabetic co-morbidities. Providers from the same healthcare institution are likely to be assigned to the same community. While most communities have high within-community utilization and spending, at 85% and 86% respectively, leakage still persists. Hence, we utilize a metric from import-export analysis to

  5. Electro-optical time gating based on Mach-Zehnder modulator for multiple access interference elimination in optical code-division multiple access networks

    Science.gov (United States)

    Chen, Yinfang; Wang, Rong; Fang, Tao; Pu, Tao; Xiang, Peng; Zheng, Jilin; Zhu, Huatao

    2014-05-01

    An electro-optical time gating technique, which is based on an electrical return-to-zero (RZ) pulse driven Mach-Zehnder modulator (MZM) for eliminating multiple access interference (MAI) in optical code-division multiple access (OCDMA) networks is proposed. This technique is successfully simulated in an eight-user two-dimensional wavelength-hopping time-spreading system, as well as in a three-user temporal phase encoding system. Results show that in both systems the MAI noise is efficiently removed and the average received power penalty improved. Both achieve error-free transmissions at a bit rate of 2.5 Gb/s. In addition, we also individually discuss effects of parameters in two systems, such as the extinction ratio of the MZM, the duty cycle of the driven RZ pulse, and the time misalignment between the driven pulse and the decoded autocorrelation peak, on the output bit error rate performance. Our work shows that employing a common MZM as a thresholder provides another probability and an interesting cost-effective choice for a smart size, low energy, and less complex thresholding technique for integrated detection in OCDMA networks.

  6. Integration of mental health resources in a primary care setting leads to increased provider satisfaction and patient access.

    Science.gov (United States)

    Vickers, Kristin S; Ridgeway, Jennifer L; Hathaway, Julie C; Egginton, Jason S; Kaderlik, Angela B; Katzelnick, David J

    2013-01-01

    This evaluation assessed the opinions and experiences of primary care providers and their support staff before and after implementation of expanded on-site mental health services and related system changes in a primary care clinic. Individual semistructured interviews, which contained a combination of open-ended questions and rating scales, were used to elicit opinions about mental health services before on-site system and resource changes occurred and repeated following changes that were intended to improve access to on-site mental health care. In the first set of interviews, prior to expanding mental health services, primary care providers and support staff were generally dissatisfied with the availability and scheduling of on-site mental health care. Patients were often referred outside the primary care clinic for mental health treatment, to the detriment of communication and coordinated care. Follow-up interviews conducted after expansion of mental health services, scheduling refinements and other system changes revealed improved provider satisfaction in treatment access and coordination of care. Providers appreciated immediate and on-site social worker availability to triage mental health needs and help access care, and on-site treatment was viewed as important for remaining informed about patient care the primary care providers are not delivering directly. Expanding integrated mental health services resulted in increased staff and provider satisfaction. Our evaluation identified key components of satisfaction, including on-site collaboration and assistance triaging patient needs. The sustainability of integrated models of care requires additional study. © 2013.

  7. Access, engagement, networks, and norms: Dimensions of social capital at work in a first grade classroom

    Science.gov (United States)

    Wexler-Robock, Stephanie

    Social capital refers to access and use of resources available through one's networks to solve problems, and the norms that reflect inclusive or exclusive access to those networks and resources. Research has found positive relationships between social capital, academic achievement, and attainment. Studies, however, have generally examined social capital through factors that occur outside the classroom; students who have social capital, acquired through their family and community relationships, seem to be more successful academically. Limited research has explored what if any factors within the classroom might impact the production, and nature of social capital, or its workings in a classroom. The purpose of this study was to explore the workings and nature of classroom social capital, including its possible relationships to engagement and cognition among 5 student participants. Using methods of qualitative data collection, mixed methods were used to analyze information resources, participants' networking, student work, and classroom discourse. Eight interdependent networking factors and 3 overarching patterns of norms were discovered. The networking factors reflected the structure, content, processes, purposes, and acceptability of participants' networking. The norms, also working interdependently, appeared to promote or inhibit among other things, engagement in networking, help seeking, access, sharing, and intertextual use of diverse, often complex sources of information. Through interaction of the 8 factors and 3 overarching norms, ongoing outcomes of networking appeared to include the creation of bridging (inclusive) and bonding (exclusive) forms of social capital, and depth of scientific conceptual understanding, in this case, about birds. Bridging social capital appeared related to willingness to engage in strong and weak tie networking, help seeking, intertextuality, and possibly to mastery goal orientation for all participants, regardless of reading level

  8. Heterogeneous wireless/wireline optical access networks with the R-EAT as backend component

    Science.gov (United States)

    Hagedorn, Klaus; Gindera, Ralf; Stohr, Andreas; Jager, Dieter

    2004-09-01

    A heterogeneous wireless/wireline optical transmission link using a reflection type electroabsorption transceiver (R-EAT) is presented. Simultaneous transmission of full-duplex broadband wireless LAN (WLAN) channels and 1Gb/s base band data is experimentally demonstrated. The system link employs sub-carrier multiplexing (SCM) and two optical channels for full duplex transmission of various analog WLAN channels and downlink digital base band data. The developed link architecture is suitable for simultaneous transmission of broadband wireline and wireless signals, it enables the coexistence and interoperability between wireline and wireless access technologies. The developed R-EAT component employed in this wireline/wireless access system, features "single-chip-component" base stations in access networks with star type topology where only a single optical fiber is used for bidirectional optical transmission. The R-EAT can be used within the optical C-band (1530- 1560nm) and is suitable for (D)WDM networks. Bit error rate measurements demonstrate the capabilities of the R-EAT for 1Gb/s base band transmission. The analog performance for WLAN transmission is characterised by a spurious free dynamic range (SFDR) of more than 75dB and 90dB for uplink and downlink transmission, respectively. The link gain for uplink and downlink transmission is -42dB and -37dB, respectively. The demonstrates the analog performances of the R-EAT for being used in wireless access networks such as W-LAN.

  9. Quality of Recovery Evaluation of the Protection Schemes for Fiber-Wireless Access Networks

    Science.gov (United States)

    Fu, Minglei; Chai, Zhicheng; Le, Zichun

    2016-03-01

    With the rapid development of fiber-wireless (FiWi) access network, the protection schemes have got more and more attention due to the risk of huge data loss when failures occur. However, there are few studies on the performance evaluation of the FiWi protection schemes by the unified evaluation criterion. In this paper, quality of recovery (QoR) method was adopted to evaluate the performance of three typical protection schemes (MPMC scheme, OBOF scheme and RPMF scheme) against the segment-level failure in FiWi access network. The QoR models of the three schemes were derived in terms of availability, quality of backup path, recovery time and redundancy. To compare the performance of the three protection schemes comprehensively, five different classes of network services such as emergency service, prioritized elastic service, conversational service, etc. were utilized by means of assigning different QoR weights. Simulation results showed that, for the most service cases, RPMF scheme was proved to be the best solution to enhance the survivability when planning the FiWi access network.

  10. Optical interconnection network for parallel access to multi-rank memory in future computing systems.

    Science.gov (United States)

    Wang, Kang; Gu, Huaxi; Yang, Yintang; Wang, Kun

    2015-08-10

    With the number of cores increasing, there is an emerging need for a high-bandwidth low-latency interconnection network, serving core-to-memory communication. In this paper, aiming at the goal of simultaneous access to multi-rank memory, we propose an optical interconnection network for core-to-memory communication. In the proposed network, the wavelength usage is delicately arranged so that cores can communicate with different ranks at the same time and broadcast for flow control can be achieved. A distributed memory controller architecture that works in a pipeline mode is also designed for efficient optical communication and transaction address processes. The scaling method and wavelength assignment for the proposed network are investigated. Compared with traditional electronic bus-based core-to-memory communication, the simulation results based on the PARSEC benchmark show that the bandwidth enhancement and latency reduction are apparent.

  11. Changes in perceptions of quality of, and access to, services among clients of a fractional franchise network in Nepal.

    Science.gov (United States)

    Agha, Sohail; Gage, Anastasia; Balal, Asma

    2007-05-01

    With declining levels of international donor funding for financing reproductive health programmes, developing country governments and international donors are looking towards private sector strategies to expand the supply of quality reproductive health services. One of the challenges of a health franchise is to improve the quality of services provided by independent private practitioners. Private providers are more likely to abide by the quality standards set by a franchiser if they see a financial benefit resulting from franchise participation. This study was conducted to measure whether (a) there were improvements in perceived quality of care and perceived access to health facilities once these facilities became part of a franchise and (b) improvements in perceived quality and perceived access were associated with increased client loyalty to franchised clinics. Franchisees were given basic reproductive health training for seven days and services marketing training for two days. Exit interviews were conducted with male and female clients at health facilities. A pre-test measurement was taken in April 2001, prior to the start of project activities. A post-test measurement was taken in February/March 2002, about 9 months after the pre-test. Multilevel regression analysis, which takes the hierarchical structure of the data into account, was used for the analysis. After taking provider-level variation into account and controlling for client characteristics, the analyses showed significant improvements in perceived quality of care and perceived access to services. Private provider participation in a franchise network helps improve client perceptions of quality of, and access to, services. Improvements in client perceptions of quality and access contribute to increased client loyalty to franchised clinics. Once increased client loyalty translates into higher client volumes, providers are likely to see the benefits of franchise participation. In turn, this should lead to

  12. 47 CFR 79.2 - Accessibility of programming providing emergency information.

    Science.gov (United States)

    2010-10-01

    ..., widespread fires, discharge of toxic gases, widespread power failures, industrial explosions, civil disorders... of programming providing emergency information. (a) Definitions. (1) For purposes of this section, the definitions in §§ 79.1 and 79.3 apply. (2) Emergency information. Information, about a current...

  13. Nectar accessibility determines fitness, flower choice and abundance of hoverflies that provide natural pest control

    NARCIS (Netherlands)

    van Rijn, Paul C. J.; Wäckers, Felix L.

    2016-01-01

    In modern agricultural landscapes, many organisms providing ecosystem services such as pollination and natural pest control are likely constrained by shortage of nectar and/or pollen required for adult nutrition. More and more flower-rich field margin strips and other habitats are created to

  14. Nectar accessibility determines fitness, flower choice and abundance of hoverflies that provide natural pest control

    NARCIS (Netherlands)

    van Rijn, P.C.J.; Wäckers, F.L.

    2016-01-01

    1. In modern agricultural landscapes, many organisms providing ecosystem services such as pollination and natural pest control are likely constrained by shortage of nectar and/or pollen required for adult nutrition. More and more flower-rich field margin strips and other habitats are created to

  15. Providing Interactive Access to Cave Geology for All Students, Regardless of Physical Ability

    Science.gov (United States)

    Atchison, C. `; Stredney, D.; Hittle, B.; Irving, K.; Toomey, R. S., III; Lemon, N. N.; Price, A.; Kerwin, T.

    2013-12-01

    Based on an identified need to accommodate students with mobility impairments in field-based instructional experiences, this presentation will discuss current efforts to promote participation, broaden diversity, and impart a historical perspective in the geosciences through the use of an interactive virtual environment. Developed through the integration of emerging simulation technologies, this prototypical virtual environment is created from LIDAR data of the Historic Tour route of Mammoth Cave National Park. The educational objectives of the simulation focus on four primary locations within the tour route that provide evidence of the hydrologic impact on the cave and karst formation. The overall objective is to provide a rich experience of a geological field-based learning for all students, regardless of their physical abilities. Employing a virtual environment that interchangeably uses two and three-dimensional representation of geoscience content, this synthetic field-based cave and karst module will provide an opportunity to assess the effectiveness in engaging the student community, and its efficacy in the curriculum when used as an alternative representation of a traditional field experience. The expected outcome is that based on the level of interactivity, the simulated environment will provide adequate pedagogical representation for content transfer without the need for physical experience in the uncontrolled field environment. Additionally, creating such an environment will impact all able-bodied students by providing supplemental resources that can both precede a traditional field experience and allow for students to re-examine a field site long after a the field experience, in both current formal and informal educational settings.

  16. Providing probability distributions for the causal pathogen of clinical mastitis using naive Bayesian networks

    NARCIS (Netherlands)

    Steeneveld, W.; Gaag, van der L.C.; Barkema, H.W.; Hogeveen, H.

    2009-01-01

    Clinical mastitis (CM) can be caused by a wide variety of pathogens and farmers must start treatment before the actual causal pathogen is known. By providing a probability distribution for the causal pathogen, naive Bayesian networks (NBN) can serve as a management tool for farmers to decide which

  17. The educational impact of the Specialty Care Access Network-Extension of Community Healthcare Outcomes program.

    Science.gov (United States)

    Salgia, Reena J; Mullan, Patricia B; McCurdy, Heather; Sales, Anne; Moseley, Richard H; Su, Grace L

    2014-11-01

    With the aging hepatitis C cohort and increasing prevalence of fatty liver disease, the burden on primary care providers (PCPs) to care for patients with liver disease is growing. In response, the Veterans Administration implemented initiatives for primary care-specialty referral to increase PCP competency in complex disease management. The Specialty Care Access Network-Extension of Community Healthcare Outcomes (SCAN-ECHO) program initiative was designed to transfer subspecialty knowledge to PCPs through case-based distance learning combined with real-time consultation. There is limited information regarding the initiative's ability to engage PCPs to learn and influence their practice. We surveyed PCPs to determine the factors that led to their participation in this program and the educational impact of participation. Of 51 potential participants, 24 responded to an anonymous survey. More than 75% of respondents participated more than one time in a SCAN-ECHO clinic. Providers were motivated to participate by a desire to learn more about liver disease, to apply the knowledge gained to future patients, and to save their patients time traveling to another center for specialty consultation. Seventy-one percent responded that the didactic component and case-based discussion were equally important. It is important that participation changed clinical practice: 75% of providers indicated they had personally discussed the information they learned from the case presentations with their colleague(s), and 42% indicated they helped a colleague care for their patient with the knowledge learned during discussions of other participants' cases. This study shows that the SCAN-ECHO videoconferencing program between PCPs and specialists can educate providers in the delivery of specialty care from a distance and potentially improve healthcare delivery.

  18. Tractable Stochastic Geometry Model for IoT Access in LTE Networks

    KAUST Repository

    Gharbieh, Mohammad; Elsawy, Hesham; Bader, Ahmed; Alouini, Mohamed-Slim

    2017-01-01

    The Internet of Things (IoT) is large-scale by nature. This is not only manifested by the large number of connected devices, but also by the high volumes of traffic that must be accommodated. Cellular networks are indeed a natural candidate for the data tsunami the IoT is expected to generate in conjunction with legacy human-type traffic. However, the random access process for scheduling request represents a major bottleneck to support IoT via LTE cellular networks. Accordingly, this paper develops a mathematical framework to model and study the random access channel (RACH) scalability to accommodate IoT traffic. The developed model is based on stochastic geometry and discrete time Markov chains (DTMC) to account for different access strategies and possible sources of inter-cell and intra-cell interferences. To this end, the developed model is utilized to assess and compare three different access strategies, which incorporate a combination of transmission persistency, back-off, and power ramping. The analysis and the results showcased herewith clearly illustrate the vulnerability of the random access procedure as the IoT intensity grows. Finally, the paper offers insights into effective scenarios for each transmission strategy in terms of IoT intensity and RACH detection thresholds.

  19. Switched-based interference reduction scheme for open-access overlaid cellular networks

    KAUST Repository

    Radaydeh, Redha Mahmoud Mesleh

    2012-06-01

    Femtocells have been proposed to enhance the spatial coverage and system capacity of existing cellular networks. However, this technology may result in significant performance loss due to the increase in co-channel interference, particularly when coordination between access points is infeasible. This paper targets interference management in such overlaid networks. It is assumed that the femtocells employ the open-access strategy to reduce cross-tier interference, and can share resources concurrently. It is also assumed that each end user (EU) can access one channel at a time, and transfer limited feedback. To reduce the effect of co-tier interference in the absence of the desired EU channel state information (CSI) at the serving access point as well as coordination between active access points, a switched scheme based on the interference levels associated with available channels is proposed. Through the analysis, the scheme modes of operation in under-loaded and over-loaded channels are studied, from which the statistics of the resulting interference power are quantified. The impact of the proposed scheme on the received desired power is thoroughly discussed. In addition, the effect of the switching threshold on the achieved performance of the desired EU is investigated. The results clarify that the proposed scheme can improve the performance while reducing the number of examined channels and feedback load. © 2012 IEEE.

  20. Tractable Stochastic Geometry Model for IoT Access in LTE Networks

    KAUST Repository

    Gharbieh, Mohammad

    2017-02-07

    The Internet of Things (IoT) is large-scale by nature. This is not only manifested by the large number of connected devices, but also by the high volumes of traffic that must be accommodated. Cellular networks are indeed a natural candidate for the data tsunami the IoT is expected to generate in conjunction with legacy human-type traffic. However, the random access process for scheduling request represents a major bottleneck to support IoT via LTE cellular networks. Accordingly, this paper develops a mathematical framework to model and study the random access channel (RACH) scalability to accommodate IoT traffic. The developed model is based on stochastic geometry and discrete time Markov chains (DTMC) to account for different access strategies and possible sources of inter-cell and intra-cell interferences. To this end, the developed model is utilized to assess and compare three different access strategies, which incorporate a combination of transmission persistency, back-off, and power ramping. The analysis and the results showcased herewith clearly illustrate the vulnerability of the random access procedure as the IoT intensity grows. Finally, the paper offers insights into effective scenarios for each transmission strategy in terms of IoT intensity and RACH detection thresholds.

  1. Topology-selective jamming of fully-connected, code-division random-access networks

    Science.gov (United States)

    Polydoros, Andreas; Cheng, Unjeng

    1990-01-01

    The purpose is to introduce certain models of topology selective stochastic jamming and examine its impact on a class of fully-connected, spread-spectrum, slotted ALOHA-type random access networks. The theory covers dedicated as well as half-duplex units. The dominant role of the spatial duty factor is established, and connections with the dual concept of time selective jamming are discussed. The optimal choices of coding rate and link access parameters (from the users' side) and the jamming spatial fraction are numerically established for DS and FH spreading.

  2. Comparison of a Ring On-Chip Network and a Code-Division Multiple-Access On-Chip Network

    Directory of Open Access Journals (Sweden)

    Xin Wang

    2007-01-01

    Full Text Available Two network-on-chip (NoC designs are examined and compared in this paper. One design applies a bidirectional ring connection scheme, while the other design applies a code-division multiple-access (CDMA connection scheme. Both of the designs apply globally asynchronous locally synchronous (GALS scheme in order to deal with the issue of transferring data in a multiple-clock-domain environment of an on-chip system. The two NoC designs are compared with each other by their network structures, data transfer principles, network node structures, and their asynchronous designs. Both the synchronous and the asynchronous designs of the two on-chip networks are realized using a hardware-description language (HDL in order to make the entire designs suit the commonly used synchronous design tools and flow. The performance estimation and comparison of the two NoC designs which are based on the HDL realizations are addressed. By comparing the two NoC designs, the advantages and disadvantages of applying direct connection and CDMA connection schemes in an on-chip communication network are discussed.

  3. MaNIDA: Insight into the German Marine Network for Integrated Data Access

    Science.gov (United States)

    Schäfer, Angela; Scientific MaNIDA Team

    2013-04-01

    The Marine Network for Integrated Data Access (MaNIDA) builds a sustainable e-Infrastructure to support discovery and re-use of data from distinct marine and earth science data providers in Germany (see ESSI1.2 and ESSI2.2). Thereby we implement the "Data Portal of German Marine Research" for coherent discovery, view, download and dissemination of aggregated content. MaNIDA receives a unique momentum from the cooperation and financial partnership between main German marine research institutes (AWI, MARUM, HZG, GEOMAR, Uni Hamburg, Uni Kiel, Uni Bremen) and the Federal Maritime and Hydrographic Agency as well as active participation in international and major EU-initiatives (ICSU, GEOSS, SeaDataNet, EMODNET, ODIP). Together with a coherent management strategy coordinated by the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, sustainability will be achieved via the long-term commitment of framework funding by the Helmholtz Association, Germany's largest scientific research organization for large-scale facilities and scientific infrastructure. Strategic Aims The installation of the "Data Portal of German Marine Research" will address the urgent demands of the German research community for reliable and easy access to marine research data at one single point of access and truth. Primary focus will be given to data derived from nationally operated research and monitoring facilities (vessels, observatories, alert systems, etc), whereby related contextual content and publications will become an integral part of the aggregation effort. For the scientific community we define responsibilities and commitments across partners while complementing existing data repositories and the new portal with well-articulated workflows from the instrument to the data product. Necessary level of quality assurance and user support will be implemented to achieve substantial enhancements in the whole lifecycle management of marine scientific data. The creation of a data

  4. Coherent detection passive optical access network enabling converged delivery of broadcast and dedicated broadband services

    DEFF Research Database (Denmark)

    Osadchiy, Alexey Vladimirovich; Prince, Kamau; Guerrero Gonzalez, Neil

    2011-01-01

    We propose a passive optical network architecture based on coherent detection for converged delivery of broadcast services from a dedicated remote broadcast server and user-specific services from a local central office. We experimentally demonstrate this architecture with mixed traffic types....... The broadcast channels were transmitted over 78 km of single mode fiber to a central office where they were multiplexed with the unicast channels for further fiber transmission over 34-km to reach the access network. Successful detection of all channels is demonstrated....

  5. Improving collaboration between primary care research networks using Access Grid technology

    Directory of Open Access Journals (Sweden)

    Zsolt Nagykaldi

    2008-05-01

    Full Text Available Access Grid (AG is an Internet2-driven, high performance audio_visual conferencing technology used worldwide by academic and government organisations to enhance communication, human interaction and group collaboration. AG technology is particularly promising for improving academic multi-centre research collaborations. This manuscript describes how the AG technology was utilised by the electronic Primary Care Research Network (ePCRN that is part of the National Institutes of Health (NIH Roadmap initiative to improve primary care research and collaboration among practice- based research networks (PBRNs in the USA. It discusses the design, installation and use of AG implementations, potential future applications, barriers to adoption, and suggested solutions.

  6. New resource allocation scheme for cognitive relay networks with opportunistic access

    KAUST Repository

    Zafar, Ammar

    2012-06-01

    In this paper, a new resource allocation scheme to minimize Symbol Error rate (SER) for relay assisted cognitive radio networks is studied. A cognitive relay network with amplify-and-forward (AF) fixed gain relays and opportunistic access to the licensed spectrum is considered. The SER objective function and the optimization constraints are derived first. The resource allocation algorithm is then derived using the Langrangian multiplier method. Closed form expressions are derived for the source and relay powers and, symbol time. Analytical results show that the optimal power allocation follows an extended water-filling solution. © 2012 IEEE.

  7. Enhancing User Access to Australian marine data - the Australian Ocean Data Network

    Science.gov (United States)

    Proctor, R.; Mancini, S.; Blain, P. J.

    2017-12-01

    The Integrated Marine Observing System (IMOS) is a national project funded by the Australian government established to deliver ocean observations to the marine and climate science community. Now in its 10th year its mission is to undertake systematic and sustained observations and to turn them into data, products and analyses that can be freely used and reused for broad societal benefits. As IMOS has matured as an observing system the expectation of the system's availability and reliability has also increased and IMOS is now seen as delivering `operational' information; it does this through the Australian Ocean Data Network (AODN). The AODN runs its services in the commercial cloud service Amazon Web Services. This has enabled the AODN to improve the system architecture, utilizing more advanced features like object storage (S3 - Simple Storage Service) and autoscaling features, and introducing new checking and logging procedures in a pipeline approach. This has improved data availability and resilience while protecting against human errors in data handling and providing a more efficient ingestion process. Many of these features are available through AODN to the wider Australian marine and science community enabling the `family' of AODN to grow, thereby enabling rapid access to an increasing collection of ocean observations.

  8. Providing cleaner energy access in Indonesia through the megaproject of kerosene conversion to LPG

    International Nuclear Information System (INIS)

    Budya, Hanung; Yasir Arofat, Muhammad

    2011-01-01

    In 2007 Indonesia undertook a massive energy program to convert its primary cooking fuel from kerosene to LPG in more than 50 million households. This megaproject, to be completed in late 2011, provided an improved household cooking fuel, with its associated benefits in user costs, cleanliness, convenience, and environment, and reduced the government's huge subsidy for petroleum fuels. Presented from the perspective of Pertamina, Indonesia's sole NOC, and the program implementer, this paper describes the background of the fuels situation, the planning stages, including the preparatory analytical work, targeted market surveys and tests, and the subsequent building of the financial, technical, and institutional models for carrying out the program on an expeditious schedule. It presents the project's major execution steps, results of the program to date, and the unique institutional roles of each party, including the activities and benefits for the government, Pertamina, the public, the industry, and the crucial agents in the fuel supply chains. Finally there is a retrospective policy analysis and a discussion of key factors and challenges in the execution of Indonesia's largest-ever energy initiative to provide improved cooking fuel.

  9. Framework for implementation of maintenance management in distribution network service providers

    International Nuclear Information System (INIS)

    Gomez Fernandez, Juan Francisco; Crespo Marquez, Adolfo

    2009-01-01

    Distribution network service providers (DNSP) are companies dealing with network infrastructure, such as distribution of gas, water, electricity or telecommunications, and they require the development of special maintenance management (MM) capabilities in order to satisfy the needs of their customers. In this sector, maintenance management information systems are essential to ensure control, gain knowledge and improve decision making. The aim of this paper is the study of specific characteristics of maintenance in these types of companies. We will investigate existing standards and best management practices with the scope of defining a suitable ad-hoc framework for implementation of maintenance management. The conclusion of the work supports the proposition of a framework consisting on a processes framework based on a structure of systems, integrated for continuous improvement of maintenance activities. The paper offers a very practical approach to the problem, as a result of more of 10 years of professional experience within this sector, and specially focused to network maintenance.

  10. Can online networks provide quality answers to questions about occupational safety and health?

    Science.gov (United States)

    Rhebergen, Martijn D F; Lenderink, Annet F; van Dijk, Frank J H; Hulshof, Carel T J

    2012-05-01

    To assess whether experts can provide high-quality answers to occupational safety and health (OSH) questions in online Question & Answer (Q&A) networks. The authors evaluated the quality of answers provided by qualified experts in two Dutch online networks: ArboAntwoord and the Helpdesk of the Netherlands Center for Occupational Diseases. A random sample of 594 answers was independently evaluated by two raters using nine answer quality criteria. An additional criterion, the agreement of answers with the best available evidence, was explored by peer review of a sample of 42 answers. Reviewers performed an evidence search in Medline. The median answer quality score of ArboAntwoord (N=295) and the Netherlands Center for Occupational Diseases Helpdesk (N=299) was 8 of 9 (IQR 2). The inter-rater reliability of the first nine quality criteria was high (κ 0.82-0.90, p<0.05). A question answered by two or more experts had a greater probability of a high-quality score than questions answered by one expert (OR 4.9, 95% CI 2.7 to 9.0). Answers most often scored insufficient on the use of evidence to underpin the answer (36% and 38% for the networks, respectively) and on conciseness (35% and 31%, respectively). Peer review demonstrated that 43%-72% of the answers in both online networks were in complete agreement with the best available evidence. OSH experts are able to provide quality answers in online OSH Q&A networks. Our answer quality appraisal instrument was feasible and provided information on how to improve answer quality.

  11. Providing access to risk prediction tools via the HL7 XML-formatted risk web service.

    Science.gov (United States)

    Chipman, Jonathan; Drohan, Brian; Blackford, Amanda; Parmigiani, Giovanni; Hughes, Kevin; Bosinoff, Phil

    2013-07-01

    Cancer risk prediction tools provide valuable information to clinicians but remain computationally challenging. Many clinics find that CaGene or HughesRiskApps fit their needs for easy- and ready-to-use software to obtain cancer risks; however, these resources may not fit all clinics' needs. The HughesRiskApps Group and BayesMendel Lab therefore developed a web service, called "Risk Service", which may be integrated into any client software to quickly obtain standardized and up-to-date risk predictions for BayesMendel tools (BRCAPRO, MMRpro, PancPRO, and MelaPRO), the Tyrer-Cuzick IBIS Breast Cancer Risk Evaluation Tool, and the Colorectal Cancer Risk Assessment Tool. Software clients that can convert their local structured data into the HL7 XML-formatted family and clinical patient history (Pedigree model) may integrate with the Risk Service. The Risk Service uses Apache Tomcat and Apache Axis2 technologies to provide an all Java web service. The software client sends HL7 XML information containing anonymized family and clinical history to a Dana-Farber Cancer Institute (DFCI) server, where it is parsed, interpreted, and processed by multiple risk tools. The Risk Service then formats the results into an HL7 style message and returns the risk predictions to the originating software client. Upon consent, users may allow DFCI to maintain the data for future research. The Risk Service implementation is exemplified through HughesRiskApps. The Risk Service broadens the availability of valuable, up-to-date cancer risk tools and allows clinics and researchers to integrate risk prediction tools into their own software interface designed for their needs. Each software package can collect risk data using its own interface, and display the results using its own interface, while using a central, up-to-date risk calculator. This allows users to choose from multiple interfaces while always getting the latest risk calculations. Consenting users contribute their data for future

  12. Centralized light-source optical access network based on polarization multiplexing.

    Science.gov (United States)

    Grassi, Fulvio; Mora, José; Ortega, Beatriz; Capmany, José

    2010-03-01

    This paper presents and demonstrates a centralized light source optical access network based on optical polarization multiplexing technique. By using two optical sources emitting light orthogonally polarized in the Central Node for downstream and upstream operations, the Remote Node is kept source-free. EVM values below telecommunication standard requirements have been measured experimentally when bidirectional digital signals have been transmitted over 10 km of SMF employing subcarrier multiplexing technique in the electrical domain.

  13. Self-optimized admission control for multi-tenant radio access networks

    OpenAIRE

    Pérez Romero, Jordi; Sallent Roig, José Oriol; Ferrús Ferré, Ramón Antonio; Agustí Comes, Ramon

    2018-01-01

    © 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. Multi-tenant Radio Access Networks (RANs) are envisaged to play a key role in highly dense scenarios for fulfil...

  14. Accessibility

    DEFF Research Database (Denmark)

    Brooks, Anthony Lewis

    2017-01-01

    This contribution is timely as it addresses accessibility in regards system hardware and software aligned with introduction of the Twenty-First Century Communications and Video Accessibility Act (CVAA) and adjoined game industry waiver that comes into force January 2017. This is an act created...... by the USA Federal Communications Commission (FCC) to increase the access of persons with disabilities to modern communications, and for other purposes. The act impacts advanced communications services and products including text messaging; e-mail; instant messaging; video communications; browsers; game...... platforms; and games software. However, the CVAA has no legal status in the EU. This text succinctly introduces and questions implications, impact, and wider adoption. By presenting the full CVAA and game industry waiver the text targets to motivate discussions and further publications on the subject...

  15. Reaching out to the forgotten: providing access to medical care for the homeless in Italy.

    Science.gov (United States)

    De Maio, Gianfranco; Van den Bergh, Rafael; Garelli, Silvia; Maccagno, Barbara; Raddi, Freja; Stefanizzi, Alice; Regazzo, Costantina; Zachariah, Rony

    2014-06-01

    A program for outpatient and intermediate inpatient care for the homeless was pioneered by the humanitarian organization Médecins Sans Frontières (MSF) in Milan, Italy, during the winter of 2012-2013. We aimed to document the characteristics and clinical management of inpatients and outpatients seen during this program. A clinic providing outpatient and intermediate inpatient care (24 bed capacity) was set up in an existing homeless hostel. Patients were admitted for post-hospitalization intermediate care or for illnesses not requiring secondary care. This study was a retrospective audit of the routine program data. Four hundred and fifty four individuals presented for outpatient care and 123 patients were admitted to inpatient intermediary care. On average one outpatient consultation was conducted per patient per month, most for acute respiratory tract infections (39.8%; 522/1311). Eleven percent of all outpatients suffered from an underlying chronic condition and 2.98% (38/1311) needed referral to emergency services or secondary care facilities. Most inpatients were ill patients referred through public reception centers (72.3%; 89/123), while 27.6% (34/123) were post-hospitalization patients requiring intermediate care. Out of all inpatients, 41.4% (51/123) required more than 1 week of care and 6.5% (8/123) needed counter-referral to secondary care. The observed service usage, morbidity patterns, relatively long lengths of stay, high referral completion and need for counter-referrals, all reflect the important gap-filling role played by an intermediate care facility for this vulnerable population. We recommend that in similar contexts, medical non-governmental organizations (NGOs) focus on the setup of inpatient intermediary care services; while outpatient services are covered by the public health system. © The Author 2014. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.

  16. The U.S. Culture Collection Network Responding to the Requirements of the Nagoya Protocol on Access and Benefit Sharing

    Directory of Open Access Journals (Sweden)

    Kevin McCluskey

    2017-08-01

    Full Text Available The U.S. Culture Collection Network held a meeting to share information about how culture collections are responding to the requirements of the recently enacted Nagoya Protocol on Access to Genetic Resources and the Fair and Equitable Sharing of Benefits Arising from their Utilization to the Convention on Biological Diversity (CBD. The meeting included representatives of many culture collections and other biological collections, the U.S. Department of State, U.S. Department of Agriculture, Secretariat of the CBD, interested scientific societies, and collection groups, including Scientific Collections International and the Global Genome Biodiversity Network. The participants learned about the policies of the United States and other countries regarding access to genetic resources, the definition of genetic resources, and the status of historical materials and genetic sequence information. Key topics included what constitutes access and how the CBD Access and Benefit-Sharing Clearing-House can help guide researchers through the process of obtaining Prior Informed Consent on Mutually Agreed Terms. U.S. scientists and their international collaborators are required to follow the regulations of other countries when working with microbes originally isolated outside the United States, and the local regulations required by the Nagoya Protocol vary by the country of origin of the genetic resource. Managers of diverse living collections in the United States described their holdings and their efforts to provide access to genetic resources. This meeting laid the foundation for cooperation in establishing a set of standard operating procedures for U.S. and international culture collections in response to the Nagoya Protocol.

  17. An Access Control Protocol for Wireless Sensor Network Using Double Trapdoor Chameleon Hash Function

    Directory of Open Access Journals (Sweden)

    Tejeshwari Thakur

    2016-01-01

    Full Text Available Wireless sensor network (WSN, a type of communication system, is normally deployed into the unattended environment where the intended user can get access to the network. The sensor nodes collect data from this environment. If the data are valuable and confidential, then security measures are needed to protect them from the unauthorized access. This situation requires an access control protocol (ACP in the design of sensor network because of sensor nodes which are vulnerable to various malicious attacks during the authentication and key establishment and the new node addition phase. In this paper, we propose a secured ACP for such WSN. This protocol is based on Elliptic Curve Discrete Log Problem (ECDLP and double trapdoor chameleon hash function which secures the WSN from malicious attacks such as node masquerading attack, replay attack, man-in-the-middle attack, and forgery attacks. Proposed ACP has a special feature known as session key security. Also, the proposed ACP is more efficient as it requires only one modular multiplication during the initialization phase.

  18. The accessibility of Poland’s Space to the Trans-European Transport Network

    Directory of Open Access Journals (Sweden)

    Wiśniewski Szymon

    2017-09-01

    Full Text Available The aim of the article is to analyse the land transport accessibility of two trans-European corridors within the boundaries of Poland. The adjustment of the course of transport routes to the distribution of the population and the country’s land development (including economic potential and logistic infrastructure was outlined using measurements of cumulative accessibility. The results were presented in both cartographic form (isochrone approach and tabular form (cumulative approach. Research was conducted adopting different forms of transport used for relocation (including foot traffic, car, rail and multimodal transport and both the current and target layout of the transport network. This made it possible to determine the changes that will effectively run the process of investment in transport infrastructure on Polish territory. This allowed the identification of the areas of Poland which are particularly conveniently located in relation to domestic connections (in terms of the international network and those for which the European transport network remains difficult to access.

  19. The role of Ethernet in providing state-of-the-art and protected industrial networking

    Energy Technology Data Exchange (ETDEWEB)

    Hammond, J. [GarrettCom Inc., Fremont, CA (United States)

    2006-07-01

    Many networks in power substations are now using Ethernet-based solutions that use specialized protocols and customized controls. This paper discussed the advantages of using Ethernet in power utility network systems. Threats to computer networks supporting process control and supervisory control and data acquisition (SCADA) systems in power utilities also were discussed, and systems and components at risk were reviewed. Higher Ethernet bandwidths now permit more data and control information to be processed by networks. Ethernet bandwidths can be used for physical security functions as well as for the control of processes and systems. Components have now been designed to provide end-to-end Ethernet installations in order to save training costs. New security features include anti-hacking protocols, firewalls, and password protection, and card and badge readers for physical intrusion protection. Traffic restrictions have been implemented between designed ports in order to create secure traffic domains. It was concluded that Ethernet can provide the level of security needed to protect important energy infrastructure.

  20. COMPETITIVENESS, MARKETING ACCESS, AND NETWORK CAPABILITY AND ITS IMPACTS ON MARKETING PERFORMANCE

    Directory of Open Access Journals (Sweden)

    Teguh Iman Sayekti

    2016-12-01

    Full Text Available This study is to determine what factors influencingthe performance of SMEs. The population in this study is SMEs in the Central Java. Sample collection was conducted with a purposive sampling method. Criteriaused to take into accountis the SMEs that are already running at leastfortwo years. The sample in this study is intended as the representative of total population,67 (sixty seven. The data were processed and analyzed by computer program of SPSS 20 for Windows. Based on the results of regression analysis, it can be concluded that competitiveness has positive and significant impact on marketing performance marketing access has positive and significant impact on marketing performance. It means that the higher competitiveness and marketing access, the higher its performance. Competitiveness and marketing access have influence on SMEs’ performance through network capability.   

  1. Image transmission in multicore-fiber code-division multiple access network

    Science.gov (United States)

    Yang, Guu-Chang; Kwong, Wing C.

    1997-01-01

    Recently, two-dimensional (2-D) signature patterns were proposed to encode binary digitized image pixels in optical code-division multiple-access (CDMA) networks with 'multicore' fiber. The new technology enables parallel transmission and simultaneous access of 2-D images in multiple-access environment, where these signature patterns are defined as optical orthogonal signature pattern codes (OOSPCs). However, previous work on OOSPCs assumed that the weight of each signature pattern was the same. In this paper, we construct a new family of OOSPCs with the removal of this assumption. Since varying the weight of a user's signature pattern affects that user's performance, this approach is useful for CDMA optical systems with multiple performance requirements.

  2. Protein Solvent-Accessibility Prediction by a Stacked Deep Bidirectional Recurrent Neural Network

    Directory of Open Access Journals (Sweden)

    Buzhong Zhang

    2018-05-01

    Full Text Available Residue solvent accessibility is closely related to the spatial arrangement and packing of residues. Predicting the solvent accessibility of a protein is an important step to understand its structure and function. In this work, we present a deep learning method to predict residue solvent accessibility, which is based on a stacked deep bidirectional recurrent neural network applied to sequence profiles. To capture more long-range sequence information, a merging operator was proposed when bidirectional information from hidden nodes was merged for outputs. Three types of merging operators were used in our improved model, with a long short-term memory network performing as a hidden computing node. The trained database was constructed from 7361 proteins extracted from the PISCES server using a cut-off of 25% sequence identity. Sequence-derived features including position-specific scoring matrix, physical properties, physicochemical characteristics, conservation score and protein coding were used to represent a residue. Using this method, predictive values of continuous relative solvent-accessible area were obtained, and then, these values were transformed into binary states with predefined thresholds. Our experimental results showed that our deep learning method improved prediction quality relative to current methods, with mean absolute error and Pearson’s correlation coefficient values of 8.8% and 74.8%, respectively, on the CB502 dataset and 8.2% and 78%, respectively, on the Manesh215 dataset.

  3. Protein Solvent-Accessibility Prediction by a Stacked Deep Bidirectional Recurrent Neural Network.

    Science.gov (United States)

    Zhang, Buzhong; Li, Linqing; Lü, Qiang

    2018-05-25

    Residue solvent accessibility is closely related to the spatial arrangement and packing of residues. Predicting the solvent accessibility of a protein is an important step to understand its structure and function. In this work, we present a deep learning method to predict residue solvent accessibility, which is based on a stacked deep bidirectional recurrent neural network applied to sequence profiles. To capture more long-range sequence information, a merging operator was proposed when bidirectional information from hidden nodes was merged for outputs. Three types of merging operators were used in our improved model, with a long short-term memory network performing as a hidden computing node. The trained database was constructed from 7361 proteins extracted from the PISCES server using a cut-off of 25% sequence identity. Sequence-derived features including position-specific scoring matrix, physical properties, physicochemical characteristics, conservation score and protein coding were used to represent a residue. Using this method, predictive values of continuous relative solvent-accessible area were obtained, and then, these values were transformed into binary states with predefined thresholds. Our experimental results showed that our deep learning method improved prediction quality relative to current methods, with mean absolute error and Pearson's correlation coefficient values of 8.8% and 74.8%, respectively, on the CB502 dataset and 8.2% and 78%, respectively, on the Manesh215 dataset.

  4. FODA: a novel efficient multiple access protocol for highly dynamic self-organizing networks

    Science.gov (United States)

    Li, Hantao; Liu, Kai; Zhang, Jun

    2005-11-01

    Based on the concept of contention reservation for polling transmission and collision prevention strategy for collision resolution, a fair on-demand access (FODA) protocol for supporting node mobility and multihop architecture in highly dynamic self-organizing networks is proposed. In the protocol, a distributed clustering network architecture formed by self-organizing algorithm and a main idea of reserving channel resources to get polling service are adopted, so that the hidden terminal (HT) and exposed terminal (ET) problems existed in traffic transmission due to multihop architecture and wireless transmission can be eliminated completely. In addition, an improved collision prevention scheme based on binary countdown algorithm (BCA), called fair collision prevention (FCP) algorithm, is proposed to greatly eliminate unfair phenomena existed in contention access of newly active ordinary nodes and completely resolve access collisions. Finally, the performance comparison of the FODA protocol with carrier sense multiple access with collision avoidance (CSMA/CA) and polling protocols by OPNET simulation are presented. Simulation results show that the FODA protocol can overcome the disadvantages of CSMA/CA and polling protocols, and achieve higher throughput, lower average message delay and less average message dropping rate.

  5. Metro-access integrated network based on optical OFDMA with dynamic sub-carrier allocation and power distribution.

    Science.gov (United States)

    Zhang, Chongfu; Zhang, Qiongli; Chen, Chen; Jiang, Ning; Liu, Deming; Qiu, Kun; Liu, Shuang; Wu, Baojian

    2013-01-28

    We propose and demonstrate a novel optical orthogonal frequency-division multiple access (OFDMA)-based metro-access integrated network with dynamic resource allocation. It consists of a single fiber OFDMA ring and many single fiber OFDMA trees, which transparently integrates metropolitan area networks with optical access networks. The single fiber OFDMA ring connects the core network and the central nodes (CNs), the CNs are on demand reconfigurable and use multiple orthogonal sub-carriers to realize parallel data transmission and dynamic resource allocation, meanwhile, they can also implement flexible power distribution. The remote nodes (RNs) distributed in the user side are connected by the single fiber OFDMA trees with the corresponding CN. The obtained results indicate that our proposed metro-access integrated network is feasible and the power distribution is agile.

  6. SPAN: A Network Providing Integrated, End-to-End, Sensor-to-Database Solutions for Environmental Sciences

    Science.gov (United States)

    Benzel, T.; Cho, Y. H.; Deschon, A.; Gullapalli, S.; Silva, F.

    2009-12-01

    In recent years, advances in sensor network technology have shown great promise to revolutionize environmental data collection. Still, wide spread adoption of these systems by domain experts has been lacking, and these have remained the purview of the engineers who design them. While there are many data logging options for basic data collection in the field currently, scientists are often required to visit the deployment sites to retrieve their data and manually import it into spreadsheets. Some advanced commercial software systems do allow scientists to collect data remotely, but most of these systems only allow point-to-point access, and require proprietary hardware. Furthermore, these commercial solutions preclude the use of sensors from other manufacturers or integration with internet based database repositories and compute engines. Therefore, scientists often must download and manually reformat their data before uploading it to the repositories if they wish to share their data. We present an open-source, low-cost, extensible, turnkey solution called Sensor Processing and Acquisition Network (SPAN) which provides a robust and flexible sensor network service. At the deployment site, SPAN leverages low-power generic embedded processors to integrate variety of commercially available sensor hardware to the network of environmental observation systems. By bringing intelligence close to the sensed phenomena, we can remotely control configuration and re-use, establish rules to trigger sensor activity, manage power requirements, and control the two-way flow of sensed data as well as control information to the sensors. Key features of our design include (1) adoption of a hardware agnostic architecture: our solutions are compatible with several programmable platforms, sensor systems, communication devices and protocols. (2) information standardization: our system supports several popular communication protocols and data formats, and (3) extensible data support: our

  7. The Effects of a Dynamic Spectrum Access Overlay in LTE-Advanced Networks

    Energy Technology Data Exchange (ETDEWEB)

    Juan D. Deaton; Ryan E. lrwin; Luiz A. DaSilva

    2011-05-01

    As early as 2014, wireless network operators spectral capacity will be overwhelmed by a data tsunami brought on by new devices and applications. To augment spectral capacity, operators could deploy a Dynamic Spectrum Access (DSA) overlay. In the light of the many planned Long Term Evolution (LTE) network deployments, the affects of a DSA overlay have not been fully considered into the existing LTE standards. Coalescing many different aspects of DSA, this paper develops the Spectrum Accountability (SA) framework. The SA framework defines specific network element functionality, protocol interfaces, and signaling flow diagrams for LTE to support service requests and enforce rights of responsibilities of primary and secondary users, respectively. We also include a network simulation to quantify the benefits of using DSA channels to augment capacity. Based on our simulation we show that, network operators can benefit up to %40 increase in operating capacity when sharing DSA bands to augment spectral capacity. With our framework, this paper could serve as an guide in developing future LTE network standards that include DSA.

  8. Optimal Caching in Multicast 5G Networks with Opportunistic Spectrum Access

    KAUST Repository

    Emara, Mostafa

    2018-01-15

    Cache-enabled small base station (SBS) densification is foreseen as a key component of 5G cellular networks. This architecture enables storing popular files at the network edge (i.e., SBS caches), which empowers local communication and alleviates traffic congestions at the core/backhaul network. This paper develops a mathematical framework, based on stochastic geometry, to characterize the hit probability of a cache-enabled multicast 5G network with SBS multi-channel capabilities and opportunistic spectrum access. To this end, we first derive the hit probability by characterizing opportunistic spectrum access success probabilities, service distance distributions, and coverage probabilities. The optimal caching distribution to maximize the hit probability is then computed. The performance and trade-offs of the derived optimal caching distributions are then assessed and compared with two widely employed caching distribution schemes, namely uniform and Zipf caching, through numerical results and extensive simulations. It is shown that the Zipf caching almost optimal only in scenarios with large number of available channels and large cache sizes.

  9. Support networks and people with physical disabilities: social inclusion and access to health services.

    Science.gov (United States)

    Holanda, Cristina Marques de Almeida; De Andrade, Fabienne Louise Juvêncio Paes; Bezerra, Maria Aparecida; Nascimento, João Paulo da Silva; Neves, Robson da Fonseca; Alves, Simone Bezerra; Ribeiro, Kátia Suely Queiroz Silva

    2015-01-01

    This study seeks to identify the formation of social support networks of people with physical disabilities, and how these networks can help facilitate access to health services and promote social inclusion. It is a cross-sectional study, with data collected via a form applied to physically disabled persons over eighteen years of age registered with the Family Health Teams of the municipal district of João Pessoa in the state of Paraíba. It was observed that the support networks of these individuals predominantly consist of family members (parents, siblings, children, spouses) and people outside the family (friends and neighbors). However, 50% of the interviewees declared that they could not count on any support from outside the family. It was observed that the support network contributes to access to the services and participation in social groups. However, reduced social inclusion was detected, due to locomotion difficulties, this being the main barrier to social interaction. Among those individuals who began to interact in society, the part played by social support was fundamental.

  10. [Exploration of the design of media access control layer of wireless body area network for medical healthcare].

    Science.gov (United States)

    Liu, Xuemei; Ge, Baofeng

    2012-04-01

    This paper proposes a media access control (MAC) layer design for wireless body area network (WBAN) systems. WBAN is a technology that targets for wireless networking of wearable and implantable body sensors which monitor vital body signs, such as heart-rate, body temperature, blood pressure, etc. It has been receiving attentions from international organizations, e. g. the Institute of Electrical and Electronics Engineers (IEEE), due to its capability of providing efficient healthcare services and clinical management. This paper reviews the standardization procedure of WBAN and summarizes the challenge of the MAC layer design. It also discusses the methods of improving power consumption performance, which is one of the major issues of WBAN systems.

  11. Applying 4-regular grid structures in large-scale access networks

    DEFF Research Database (Denmark)

    Pedersen, Jens Myrup; Knudsen, Thomas P.; Patel, Ahmed

    2006-01-01

    4-Regular grid structures have been used in multiprocessor systems for decades due to a number of nice properties with regard to routing, protection, and restoration, together with a straightforward planar layout. These qualities are to an increasing extent demanded also in largescale access...... networks, but concerning protection and restoration these demands have been met only to a limited extent by the commonly used ring and tree structures. To deal with the fact that classical 4-regular grid structures are not directly applicable in such networks, this paper proposes a number of extensions...... concerning restoration, protection, scalability, embeddability, flexibility, and cost. The extensions are presented as a tool case, which can be used for implementing semi-automatic and in the longer term full automatic network planning tools....

  12. Statistics of the uplink co-tier interference in closed access heterogeneous networks

    KAUST Repository

    Tabassum, Hina

    2013-09-01

    In this paper, we derive a statistical model of the co-tier interference in closed access two tier heterogeneous wireless cellular networks with femtocell deployments. The derived model captures the impact of bounded path loss model, wall penetration loss, user distributions, random locations, and density of the femtocells. Firstly, we derive the analytical expressions for the probability density function (PDF) and moment generating function (MGF) of the co-tier interference considering a single femtocell interferer by exploiting the random disc line picking theory from geometric probability. We then derive the MGF of the cumulative interference from all femtocell interferers considering full spectral reuse in each femtocell. Orthogonal spectrum partitioning is assumed between the macrocell and femtocell networks to avoid any cross-tier interference. Finally, the accuracy of the derived expressions is validated through Monte-Carlo simulations and the expressions are shown to be useful in quantifying important network performance metrics such as ergodic capacity. © 2013 IEEE.

  13. Mitsunobu mischief: Neighbor-directed histidine N(π)–alkylation provides access to peptides containing selectively functionalized imidazolium heterocycles

    Science.gov (United States)

    Qian, Wen-Jian

    2015-01-01

    There are few methodologies that yield peptides containing His residues with selective N(π), N(π)-bis-alkylated imidazole rings. We have found that, under certain conditions, on-resin Mitsunobu coupling of alcohols with peptides having a N(π)-alkylated His residue results in selective and high-yield alkylation of the imidazole N(π) nitrogen. The reaction requires the presence of a proximal phosphoric, carboxylic or sulfonic acid, and proceeds through an apparent intramolecular mechanism involving Mitsunobu intermediates. These transformations have particular application to phosphopeptides, where “charge masking” of one phosphoryl anionic charge by the cationic histidine imidazolium ion is now possible. This chemistry opens selective access to peptides containing differentially functionalized imidazolium heterocycles, which provide access to new classes of peptides and peptide mimetics. PMID:25739367

  14. Advertisement-Based Energy Efficient Medium Access Protocols for Wireless Sensor Networks

    Science.gov (United States)

    Ray, Surjya Sarathi

    One of the main challenges that prevents the large-scale deployment of Wireless Sensor Networks (WSNs) is providing the applications with the required quality of service (QoS) given the sensor nodes' limited energy supplies. WSNs are an important tool in supporting applications ranging from environmental and industrial monitoring, to battlefield surveillance and traffic control, among others. Most of these applications require sensors to function for long periods of time without human intervention and without battery replacement. Therefore, energy conservation is one of the main goals for protocols for WSNs. Energy conservation can be performed in different layers of the protocol stack. In particular, as the medium access control (MAC) layer can access and control the radio directly, large energy savings is possible through intelligent MAC protocol design. To maximize the network lifetime, MAC protocols for WSNs aim to minimize idle listening of the sensor nodes, packet collisions, and overhearing. Several approaches such as duty cycling and low power listening have been proposed at the MAC layer to achieve energy efficiency. In this thesis, I explore the possibility of further energy savings through the advertisement of data packets in the MAC layer. In the first part of my research, I propose Advertisement-MAC or ADV-MAC, a new MAC protocol for WSNs that utilizes the concept of advertising for data contention. This technique lets nodes listen dynamically to any desired transmission and sleep during transmissions not of interest. This minimizes the energy lost in idle listening and overhearing while maintaining an adaptive duty cycle to handle variable loads. Additionally, ADV-MAC enables energy efficient MAC-level multicasting. An analytical model for the packet delivery ratio and the energy consumption of the protocol is also proposed. The analytical model is verified with simulations and is used to choose an optimal value of the advertisement period

  15. A sparse autoencoder-based deep neural network for protein solvent accessibility and contact number prediction.

    Science.gov (United States)

    Deng, Lei; Fan, Chao; Zeng, Zhiwen

    2017-12-28

    Direct prediction of the three-dimensional (3D) structures of proteins from one-dimensional (1D) sequences is a challenging problem. Significant structural characteristics such as solvent accessibility and contact number are essential for deriving restrains in modeling protein folding and protein 3D structure. Thus, accurately predicting these features is a critical step for 3D protein structure building. In this study, we present DeepSacon, a computational method that can effectively predict protein solvent accessibility and contact number by using a deep neural network, which is built based on stacked autoencoder and a dropout method. The results demonstrate that our proposed DeepSacon achieves a significant improvement in the prediction quality compared with the state-of-the-art methods. We obtain 0.70 three-state accuracy for solvent accessibility, 0.33 15-state accuracy and 0.74 Pearson Correlation Coefficient (PCC) for the contact number on the 5729 monomeric soluble globular protein dataset. We also evaluate the performance on the CASP11 benchmark dataset, DeepSacon achieves 0.68 three-state accuracy and 0.69 PCC for solvent accessibility and contact number, respectively. We have shown that DeepSacon can reliably predict solvent accessibility and contact number with stacked sparse autoencoder and a dropout approach.

  16. Adaptation of AMO-FBMC-OQAM in optical access network for accommodating asynchronous multiple access in OFDM-based uplink transmission

    Science.gov (United States)

    Jung, Sun-Young; Jung, Sang-Min; Han, Sang-Kook

    2015-01-01

    Exponentially expanding various applications in company with proliferation of mobile devices make mobile traffic exploded annually. For future access network, bandwidth efficient and asynchronous signals converged transmission technique is required in optical network to meet a huge bandwidth demand, while integrating various services and satisfying multiple access in perceived network resource. Orthogonal frequency division multiplexing (OFDM) is highly bandwidth efficient parallel transmission technique based on orthogonal subcarriers. OFDM has been widely studied in wired-/wireless communication and became a Long term evolution (LTE) standard. Consequently, OFDM also has been actively researched in optical network. However, OFDM is vulnerable frequency and phase offset essentially because of its sinc-shaped side lobes, therefore tight synchronism is necessary to maintain orthogonality. Moreover, redundant cyclic prefix (CP) is required in dispersive channel. Additionally, side lobes act as interference among users in multiple access. Thus, it practically hinders from supporting integration of various services and multiple access based on OFDM optical transmission In this paper, adaptively modulated optical filter bank multicarrier system with offset QAM (AMO-FBMC-OQAM) is introduced and experimentally investigated in uplink optical transmission to relax multiple access interference (MAI), while improving bandwidth efficiency. Side lobes are effectively suppressed by using FBMC, therefore the system becomes robust to path difference and imbalance among optical network units (ONUs), which increase bandwidth efficiency by reducing redundancy. In comparison with OFDM, a signal performance and an efficiency of frequency utilization are improved in the same experimental condition. It enables optical network to effectively support heterogeneous services and multiple access.

  17. Improved Iterative Decoding of Network-Channel Codes for Multiple-Access Relay Channel.

    Science.gov (United States)

    Majumder, Saikat; Verma, Shrish

    2015-01-01

    Cooperative communication using relay nodes is one of the most effective means of exploiting space diversity for low cost nodes in wireless network. In cooperative communication, users, besides communicating their own information, also relay the information of other users. In this paper we investigate a scheme where cooperation is achieved using a common relay node which performs network coding to provide space diversity for two information nodes transmitting to a base station. We propose a scheme which uses Reed-Solomon error correcting code for encoding the information bit at the user nodes and convolutional code as network code, instead of XOR based network coding. Based on this encoder, we propose iterative soft decoding of joint network-channel code by treating it as a concatenated Reed-Solomon convolutional code. Simulation results show significant improvement in performance compared to existing scheme based on compound codes.

  18. Perspectives on providing good access to dental services for elderly people: patient selection, dentists' responsibility and budget management.

    Science.gov (United States)

    Grytten, Jostein; Holst, Dorthe

    2013-06-01

    To suggest a model for organizing and financing dental services for elderly people so that they have good access to services. There are few studies on how dental services for elderly people should be organized and financed. This is surprising if we take into consideration the fact that the proportion of elderly people is growing faster than any other group in the population, and that elderly people have more dental diseases and poorer access to dental services than the rest of the adult population. In several countries, dental services are characterized by private providers who often operate in a market with competition and free price-setting. Private dentists have no community responsibility, and they are free to choose which patients they treat. Literature review and critical reasoning. In order to avoid patient selection, a patient list system for elderly people is recommended, with per capita remuneration for the patients that the dentist is given responsibility for. The patient list system means that the dentist assumes responsibility for a well-defined list of elderly people. Our model will lead to greater security in the dentist/patient relationship, and patients with great treatment needs will be ensured access to dental services. © 2012 John Wiley & Sons A/S and The Gerodontology Society. Published by John Wiley & Sons Ltd.

  19. Stochastic geometry model for multi-channel fog radio access networks

    KAUST Repository

    Emara, Mostafa

    2017-06-29

    Cache-enabled base station (BS) densification, denoted as a fog radio access network (F-RAN), is foreseen as a key component of 5G cellular networks. F-RAN enables storing popular files at the network edge (i.e., BS caches), which empowers local communication and alleviates traffic congestions at the core/backhaul network. The hitting probability, which is the probability of successfully transmitting popular files request from the network edge, is a fundamental key performance indicator (KPI) for F-RAN. This paper develops a scheduling aware mathematical framework, based on stochastic geometry, to characterize the hitting probability of F-RAN in a multi-channel environment. To this end, we assess and compare the performance of two caching distribution schemes, namely, uniform caching and Zipf caching. The numerical results show that the commonly used single channel environment leads to pessimistic assessment for the hitting probability of F-RAN. Furthermore, the numerical results manifest the superiority of the Zipf caching scheme and quantify the hitting probability gains in terms of the number of channels and cache size.

  20. Decentralized Group Sparse Beamforming for Multi-Cloud Radio Access Networks

    KAUST Repository

    Dhifallah, Oussama Najeeb

    2015-12-06

    Recent studies on cloud-radio access networks (CRANs) assume the availability of a single processor (cloud) capable of managing the entire network performance; inter-cloud interference is treated as background noise. This paper considers the more practical scenario of the downlink of a CRAN formed by multiple clouds, where each cloud is connected to a cluster of multiple-antenna base stations (BSs) via high-capacity wireline backhaul links. The network is composed of several disjoint BSs\\' clusters, each serving a pre-known set of single-antenna users. To account for both inter- cloud and intra-cloud interference, the paper considers the problem of minimizing the total network power consumption subject to quality of service constraints, by jointly determining the set of active BSs connected to each cloud and the beamforming vectors of every user across the network. The paper solves the problem using Lagrangian duality theory through a dual decomposition approach, which decouples the problem into multiple and independent subproblems, the solution of which depends on the dual optimization problem. The solution then proceeds in updating the dual variables and the active set of BSs at each cloud iteratively. The proposed approach leads to a distributed implementation across the multiple clouds through a reasonable exchange of information between adjacent clouds. The paper further proposes a centralized solution to the problem. Simulation results suggest that the proposed algorithms significantly outperform the conventional per-cloud update solution, especially at high signal-to-interference-plus- noise ratio (SINR) target.

  1. A Time-constrained Network Voronoi Construction and Accessibility Analysis in Location-based Service Technology

    Science.gov (United States)

    Yu, W.; Ai, T.

    2014-11-01

    Accessibility analysis usually requires special models of spatial location analysis based on some geometric constructions, such as Voronoi diagram (abbreviated to VD). There are many achievements in classic Voronoi model research, however suffering from the following limitations for location-based services (LBS) applications. (1) It is difficult to objectively reflect the actual service areas of facilities by using traditional planar VDs, because human activities in LBS are usually constrained only to the network portion of the planar space. (2) Although some researchers have adopted network distance to construct VDs, their approaches are used in a static environment, where unrealistic measures of shortest path distance based on assumptions about constant travel speeds through the network were often used. (3) Due to the computational complexity of the shortest-path distance calculating, previous researches tend to be very time consuming, especially for large datasets and if multiple runs are required. To solve the above problems, a novel algorithm is developed in this paper. We apply network-based quadrat system and 1-D sequential expansion to find the corresponding subnetwork for each focus. The idea is inspired by the natural phenomenon that water flow extends along certain linear channels until meets others or arrives at the end of route. In order to accommodate the changes in traffic conditions, the length of network-quadrat is set upon the traffic condition of the corresponding street. The method has the advantage over Dijkstra's algorithm in that the time cost is avoided, and replaced with a linear time operation.

  2. Optimal Design of Multitype Groundwater Monitoring Networks Using Easily Accessible Tools.

    Science.gov (United States)

    Wöhling, Thomas; Geiges, Andreas; Nowak, Wolfgang

    2016-11-01

    Monitoring networks are expensive to establish and to maintain. In this paper, we extend an existing data-worth estimation method from the suite of PEST utilities with a global optimization method for optimal sensor placement (called optimal design) in groundwater monitoring networks. Design optimization can include multiple simultaneous sensor locations and multiple sensor types. Both location and sensor type are treated simultaneously as decision variables. Our method combines linear uncertainty quantification and a modified genetic algorithm for discrete multilocation, multitype search. The efficiency of the global optimization is enhanced by an archive of past samples and parallel computing. We demonstrate our methodology for a groundwater monitoring network at the Steinlach experimental site, south-western Germany, which has been established to monitor river-groundwater exchange processes. The target of optimization is the best possible exploration for minimum variance in predicting the mean travel time of the hyporheic exchange. Our results demonstrate that the information gain of monitoring network designs can be explored efficiently and with easily accessible tools prior to taking new field measurements or installing additional measurement points. The proposed methods proved to be efficient and can be applied for model-based optimal design of any type of monitoring network in approximately linear systems. Our key contributions are (1) the use of easy-to-implement tools for an otherwise complex task and (2) yet to consider data-worth interdependencies in simultaneous optimization of multiple sensor locations and sensor types. © 2016, National Ground Water Association.

  3. Energy Efficient Medium Access Control Protocol for Clustered Wireless Sensor Networks with Adaptive Cross-Layer Scheduling.

    Science.gov (United States)

    Sefuba, Maria; Walingo, Tom; Takawira, Fambirai

    2015-09-18

    This paper presents an Energy Efficient Medium Access Control (MAC) protocol for clustered wireless sensor networks that aims to improve energy efficiency and delay performance. The proposed protocol employs an adaptive cross-layer intra-cluster scheduling and an inter-cluster relay selection diversity. The scheduling is based on available data packets and remaining energy level of the source node (SN). This helps to minimize idle listening on nodes without data to transmit as well as reducing control packet overhead. The relay selection diversity is carried out between clusters, by the cluster head (CH), and the base station (BS). The diversity helps to improve network reliability and prolong the network lifetime. Relay selection is determined based on the communication distance, the remaining energy and the channel quality indicator (CQI) for the relay cluster head (RCH). An analytical framework for energy consumption and transmission delay for the proposed MAC protocol is presented in this work. The performance of the proposed MAC protocol is evaluated based on transmission delay, energy consumption, and network lifetime. The results obtained indicate that the proposed MAC protocol provides improved performance than traditional cluster based MAC protocols.

  4. Producing More Actionable Science Isn't the Problem; It's Providing Decision-Makers with Access to Right Actionable Knowledge

    Science.gov (United States)

    Trexler, M.

    2017-12-01

    Policy-makers today have almost infinite climate-relevant scientific and other information available to them. The problem for climate change decision-making isn't missing science or inadequate knowledge of climate risks; the problem is that the "right" climate change actionable knowledge isn't getting to the right decision-maker, or is getting there too early or too late to effectively influence her decision-making. Actionable knowledge is not one-size-fit-all, and for a given decision-maker might involve scientific, economic, or risk-based information. Simply producing more and more information as we are today is not the solution, and actually makes it harder for individual decision-makers to access "their" actionable knowledge. The Climatographers began building the Climate Web five years ago to test the hypothesis that a knowledge management system could help navigate the gap between infinite information and individual actionable knowledge. Today the Climate Web's more than 1,500 index terms allow instant access to almost any climate change topic. It is a curated public-access knowledgebase of more than 1,000 books, 2,000 videos, 15,000 reports and articles, 25,000 news stories, and 3,000 websites. But it is also much more, linking together tens of thousands of individually extracted ideas and graphics, and providing Deep Dives into more than 100 key topics from changing probability distributions of extreme events to climate communications best practices to cognitive dissonance in climate change decision-making. The public-access Climate Web is uniquely able to support cross-silo learning, collaboration, and actionable knowledge dissemination. The presentation will use the Climate Web to demonstrate why knowledge management should be seen as a critical component of science and policy-making collaborations.

  5. Access Selection Algorithm of Heterogeneous Wireless Networks for Smart Distribution Grid Based on Entropy-Weight and Rough Set

    Science.gov (United States)

    Xiang, Min; Qu, Qinqin; Chen, Cheng; Tian, Li; Zeng, Lingkang

    2017-11-01

    To improve the reliability of communication service in smart distribution grid (SDG), an access selection algorithm based on dynamic network status and different service types for heterogeneous wireless networks was proposed. The network performance index values were obtained in real time by multimode terminal and the variation trend of index values was analyzed by the growth matrix. The index weights were calculated by entropy-weight and then modified by rough set to get the final weights. Combining the grey relational analysis to sort the candidate networks, and the optimum communication network is selected. Simulation results show that the proposed algorithm can implement dynamically access selection in heterogeneous wireless networks of SDG effectively and reduce the network blocking probability.

  6. An Effective Massive Sensor Network Data Access Scheme Based on Topology Control for the Internet of Things.

    Science.gov (United States)

    Yi, Meng; Chen, Qingkui; Xiong, Neal N

    2016-11-03

    This paper considers the distributed access and control problem of massive wireless sensor networks' data access center for the Internet of Things, which is an extension of wireless sensor networks and an element of its topology structure. In the context of the arrival of massive service access requests at a virtual data center, this paper designs a massive sensing data access and control mechanism to improve the access efficiency of service requests and makes full use of the available resources at the data access center for the Internet of things. Firstly, this paper proposes a synergistically distributed buffer access model, which separates the information of resource and location. Secondly, the paper divides the service access requests into multiple virtual groups based on their characteristics and locations using an optimized self-organizing feature map neural network. Furthermore, this paper designs an optimal scheduling algorithm of group migration based on the combination scheme between the artificial bee colony algorithm and chaos searching theory. Finally, the experimental results demonstrate that this mechanism outperforms the existing schemes in terms of enhancing the accessibility of service requests effectively, reducing network delay, and has higher load balancing capacity and higher resource utility rate.

  7. Designing a system for patients controlling providers' access to their electronic health records: organizational and technical challenges.

    Science.gov (United States)

    Leventhal, Jeremy C; Cummins, Jonathan A; Schwartz, Peter H; Martin, Douglas K; Tierney, William M

    2015-01-01

    Electronic health records (EHRs) are proliferating, and financial incentives encourage their use. Applying Fair Information Practice principles to EHRs necessitates balancing patients' rights to control their personal information with providers' data needs to deliver safe, high-quality care. We describe the technical and organizational challenges faced in capturing patients' preferences for patient-controlled EHR access and applying those preferences to an existing EHR. We established an online system for capturing patients' preferences for who could view their EHRs (listing all participating clinic providers individually and categorically-physicians, nurses, other staff) and what data to redact (none, all, or by specific categories of sensitive data or patient age). We then modified existing data-viewing software serving a state-wide health information exchange and a large urban health system and its primary care clinics to allow patients' preferences to guide data displays to providers. Patients could allow or restrict data displays to all clinicians and staff in a demonstration primary care clinic, categories of providers (physicians, nurses, others), or individual providers. They could also restrict access to all EHR data or any or all of five categories of sensitive data (mental and reproductive health, sexually transmitted diseases, HIV/AIDS, and substance abuse) and for specific patient ages. The EHR viewer displayed data via reports, data flowsheets, and coded and free text data displayed by Google-like searches. Unless patients recorded restrictions, by default all requested data were displayed to all providers. Data patients wanted restricted were not displayed, with no indication they were redacted. Technical barriers prevented redacting restricted information in free textnotes. The program allowed providers to hit a "Break the Glass" button to override patients' restrictions, recording the date, time, and next screen viewed. Establishing patient

  8. Wide area network access to CMS data using the LustreTM filesystem

    Science.gov (United States)

    Rodriguez, J. L.; Avery, P.; Brody, T.; Bourilkov, D.; Fu, Y.; Kim, B.; Prescott, C.; Wu, Y.

    2010-04-01

    In this paper, we explore the use of the LustreTM cluster filesystem over the wide area network to access Compact Muon Solenoid (CMS) data stored on physical devices located hundreds of kilometres away. We describe the experimental testbed and report on the I/O performance of applications writing and reading data on the distributed LustreTM filesystem established across the WAN. We compare the I/O performance of a CMS application to the performance obtained with IOzone, a standard benchmark tool. We then examine the I/O performance of the CMS application running multiple processes on a single server. And compare the Lustre results to results obtained on data stored on local filesystems. Our measurements reveal that the IOzone benchmark tool, accessing data sequentially, can saturate the Gbps network link that connects our Lustre client in Miami Florida to the Lustre storage located in Gainesville, Florida. We also find that the I/O rates of the CMS application is significantly less than what can be obtained with IOzone for sequential access to data.

  9. Wide area network access to CMS data using the LustreTM filesystem

    International Nuclear Information System (INIS)

    Rodriguez, J L; Brody, T; Avery, P; Bourilkov, D; Fu, Y; Kim, B; Wu, Y; Prescott, C

    2010-01-01

    In this paper, we explore the use of the Lustre TM cluster filesystem over the wide area network to access Compact Muon Solenoid (CMS) data stored on physical devices located hundreds of kilometres away. We describe the experimental testbed and report on the I/O performance of applications writing and reading data on the distributed Lustre TM filesystem established across the WAN. We compare the I/O performance of a CMS application to the performance obtained with IOzone, a standard benchmark tool. We then examine the I/O performance of the CMS application running multiple processes on a single server. And compare the Lustre results to results obtained on data stored on local filesystems. Our measurements reveal that the IOzone benchmark tool, accessing data sequentially, can saturate the Gbps network link that connects our Lustre client in Miami Florida to the Lustre storage located in Gainesville, Florida. We also find that the I/O rates of the CMS application is significantly less than what can be obtained with IOzone for sequential access to data.

  10. An Optimal Medium Access Control with Partial Observations for Sensor Networks

    Directory of Open Access Journals (Sweden)

    Servetto Sergio D

    2005-01-01

    Full Text Available We consider medium access control (MAC in multihop sensor networks, where only partial information about the shared medium is available to the transmitter. We model our setting as a queuing problem in which the service rate of a queue is a function of a partially observed Markov chain representing the available bandwidth, and in which the arrivals are controlled based on the partial observations so as to keep the system in a desirable mildly unstable regime. The optimal controller for this problem satisfies a separation property: we first compute a probability measure on the state space of the chain, namely the information state, then use this measure as the new state on which the control decisions are based. We give a formal description of the system considered and of its dynamics, we formalize and solve an optimal control problem, and we show numerical simulations to illustrate with concrete examples properties of the optimal control law. We show how the ergodic behavior of our queuing model is characterized by an invariant measure over all possible information states, and we construct that measure. Our results can be specifically applied for designing efficient and stable algorithms for medium access control in multiple-accessed systems, in particular for sensor networks.

  11. QoS Modeling for End-to-End Performance Evaluation over Networks with Wireless Access

    Directory of Open Access Journals (Sweden)

    Gómez Gerardo

    2010-01-01

    Full Text Available This paper presents an end-to-end Quality of Service (QoS model for assessing the performance of data services over networks with wireless access. The proposed model deals with performance degradation across protocol layers using a bottom-up strategy, starting with the physical layer and moving on up to the application layer. This approach makes it possible to analytically assess performance at different layers, thereby facilitating a possible end-to-end optimization process. As a representative case, a scenario where a set of mobile terminals connected to a streaming server through an IP access node has been studied. UDP, TCP, and the new TCP-Friendly Rate Control (TFRC protocols were analyzed at the transport layer. The radio interface consisted of a variable-rate multiuser and multichannel subsystem, including retransmissions and adaptive modulation and coding. The proposed analytical QoS model was validated on a real-time emulator of an end-to-end network with wireless access and proved to be very useful for the purposes of service performance estimation and optimization.

  12. Hybrid Access Femtocells in Overlaid MIMO Cellular Networks with Transmit Selection under Poisson Field Interference

    KAUST Repository

    Abdel Nabi, Amr A

    2017-09-21

    This paper analyzes the performance of hybrid control-access schemes for small cells (such as femtocells) in the context of two-tier overlaid cellular networks. The proposed hybrid access schemes allow for sharing the same downlink resources between the small-cell network and the original macrocell network, and their mode of operations are characterized considering post-processed signal-to-interference-plus-noise ratios (SINRs) or pre-processed interference-aware operation. The work presents a detailed treatment of achieved performance of a desired user that benefits from MIMO arrays configuration through the use of transmit antenna selection (TAS) and maximal ratio combining (MRC) in the presence of Poisson field interference processes on spatial links. Furthermore, based on the interference awareness at the desired user, two TAS approaches are treated, which are the signal-to-noise (SNR)-based selection and SINR-based selection. The analysis is generalized to address the cases of highly-correlated and un-correlated aggregated interference on different transmit channels. In addition, the effect of delayed TAS due to imperfect feedback and the impact of arbitrary TAS processing are investigated. The analytical results are validated by simulations, to clarify some of the main outcomes herein.

  13. Hybrid Access Femtocells in Overlaid MIMO Cellular Networks with Transmit Selection under Poisson Field Interference

    KAUST Repository

    Abdel Nabi, Amr A; Al-Qahtani, Fawaz S.; Radaydeh, Redha Mahmoud Mesleh; Shaqfeh, Mohammed

    2017-01-01

    This paper analyzes the performance of hybrid control-access schemes for small cells (such as femtocells) in the context of two-tier overlaid cellular networks. The proposed hybrid access schemes allow for sharing the same downlink resources between the small-cell network and the original macrocell network, and their mode of operations are characterized considering post-processed signal-to-interference-plus-noise ratios (SINRs) or pre-processed interference-aware operation. The work presents a detailed treatment of achieved performance of a desired user that benefits from MIMO arrays configuration through the use of transmit antenna selection (TAS) and maximal ratio combining (MRC) in the presence of Poisson field interference processes on spatial links. Furthermore, based on the interference awareness at the desired user, two TAS approaches are treated, which are the signal-to-noise (SNR)-based selection and SINR-based selection. The analysis is generalized to address the cases of highly-correlated and un-correlated aggregated interference on different transmit channels. In addition, the effect of delayed TAS due to imperfect feedback and the impact of arbitrary TAS processing are investigated. The analytical results are validated by simulations, to clarify some of the main outcomes herein.

  14. Performance Evaluation of TDMA Medium Access Control Protocol in Cognitive Wireless Networks

    Directory of Open Access Journals (Sweden)

    Muhammed Enes Bayrakdar

    2017-02-01

    Full Text Available Cognitive radio paradigm has been revealed as a new communication technology that shares channels in wireless networks. Channel assignment is a crucial issue in the field of cognitive wireless networks because of the spectrum scarcity. In this work, we have evaluated the performance of TDMA medium access control protocol. In our simulation scenarios, primary users and secondary users utilize TDMA as a medium access control protocol. We have designed a network environment in Riverbed simulation software that consists of primary users, secondary users, and base stations. In our system model, secondary users sense the spectrum and inform the base station about empty channels. Then, the base station decides accordingly which secondary user may utilize the empty channel. Energy detection technique is employed as a spectrum sensing technique because it is the best when information about signal of primary user is acquired. Besides, different number of users is selected in simulation scenarios in order to obtain accurate delay and throughput results. Comparing analytical model with simulation results, we have shown that performance analysis of our system model is consistent and accurate.

  15. A 10 Gb/s passive-components-based WDM-TDM reconfigurable optical access network architecture

    NARCIS (Netherlands)

    Tran, N.C.; Jung, H.D.; Okonkwo, C.M.; Tangdiongga, E.; Koonen, A.M.J.

    2011-01-01

    We propose a cost-effective, reconfigurable optical access network by employing passive components in the remote node and dual conventional optical transceivers in ONUs. The architecture is demonstrated with bidirectional transmission at 10 Gb/s.

  16. ‘Doing the hard yards’: carer and provider focus group perspectives of accessing Aboriginal childhood disability services

    Science.gov (United States)

    2013-01-01

    Background Despite a high prevalence of disability, Aboriginal Australians access disability services in Australia less than non-Aboriginal Australians with a disability. The needs of Aboriginal children with disability are particularly poorly understood. They can endure long delays in treatment which can impact adversely on development. This study sought to ascertain the factors involved in accessing services and support for Aboriginal children with a disability. Methods Using the focus group method, two community forums, one for health and service providers and one for carers of Aboriginal children with a disability, were held at an Aboriginal Community Controlled Health Service (ACCHS) in the Sydney, metropolitan area of New South Wales, Australia. Framework analysis was applied to qualitative data to elucidate key issues relevant to the dimensions of access framework. Independent coding consistency checks were performed and consensus of analysis verified by the entire research team, several of whom represented the local Aboriginal community. Results Seventeen health and social service providers representing local area government and non-government-funded health and social service organisations and five carers participated in two separate forums between September and October 2011. Lack of awareness of services and inadequate availability were prominent concerns in both groups despite geographic proximity to a major metropolitan area with significant health infrastructure. Carers noted racism, insufficient or non-existent services, and the need for an enhanced role of ACCHSs and AHWs in disability support services. Providers highlighted logistical barriers and cultural and historical issues that impacted on the effectiveness of mainstream services for Aboriginal people. Conclusions Despite dedicated disability services in an urban community, geographic proximity does not mitigate lack of awareness and availability of support. This paper has enumerated a number of

  17. A Novel Approach for Transmission of 56 Gbit/s NRZ Signal in Access Network Using Spectrum Slicing Technique

    DEFF Research Database (Denmark)

    Spolitis, S.; Vegas Olmos, Juan José; Bobrovs, V.

    2013-01-01

    We present the spectrum slicing and stitching concept for high-capacity low optics complexity optical access networks. Spectrum slicing and stitching of a 56 Gbit/s NRZ electrical signal is experimentally demonstrated for the first time.......We present the spectrum slicing and stitching concept for high-capacity low optics complexity optical access networks. Spectrum slicing and stitching of a 56 Gbit/s NRZ electrical signal is experimentally demonstrated for the first time....

  18. Geographical accessibility and spatial coverage modeling of the primary health care network in the Western Province of Rwanda

    Directory of Open Access Journals (Sweden)

    Huerta Munoz Ulises

    2012-09-01

    greatly increases the population being served to 58% of inhabitants. When considering Scenario 3, the total population served is 34.3%. Conclusions Significant spatial variations in geographical accessibility and spatial coverage were observed across the three travel scenarios. The analysis demonstrates that regardless of which travel scenario is used, the majority of the population in the Western Province does not have access to the existing primary health facility network. Our findings also demonstrate the usefulness of GIS methods to leverage multiple datasets from different sources in a spatial framework to provide support to evidence-based planning and resource allocation decision-making in developing countries.

  19. Chromatin accessibility prediction via convolutional long short-term memory networks with k-mer embedding.

    Science.gov (United States)

    Min, Xu; Zeng, Wanwen; Chen, Ning; Chen, Ting; Jiang, Rui

    2017-07-15

    Experimental techniques for measuring chromatin accessibility are expensive and time consuming, appealing for the development of computational approaches to predict open chromatin regions from DNA sequences. Along this direction, existing methods fall into two classes: one based on handcrafted k -mer features and the other based on convolutional neural networks. Although both categories have shown good performance in specific applications thus far, there still lacks a comprehensive framework to integrate useful k -mer co-occurrence information with recent advances in deep learning. We fill this gap by addressing the problem of chromatin accessibility prediction with a convolutional Long Short-Term Memory (LSTM) network with k -mer embedding. We first split DNA sequences into k -mers and pre-train k -mer embedding vectors based on the co-occurrence matrix of k -mers by using an unsupervised representation learning approach. We then construct a supervised deep learning architecture comprised of an embedding layer, three convolutional layers and a Bidirectional LSTM (BLSTM) layer for feature learning and classification. We demonstrate that our method gains high-quality fixed-length features from variable-length sequences and consistently outperforms baseline methods. We show that k -mer embedding can effectively enhance model performance by exploring different embedding strategies. We also prove the efficacy of both the convolution and the BLSTM layers by comparing two variations of the network architecture. We confirm the robustness of our model to hyper-parameters by performing sensitivity analysis. We hope our method can eventually reinforce our understanding of employing deep learning in genomic studies and shed light on research regarding mechanisms of chromatin accessibility. The source code can be downloaded from https://github.com/minxueric/ismb2017_lstm . tingchen@tsinghua.edu.cn or ruijiang@tsinghua.edu.cn. Supplementary materials are available at

  20. A distributed Synchronous reservation multiple access control protocol for mobile Ad hoc networks

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yanling; SUN Xianpu; LI Jiandong

    2007-01-01

    This study proposes a new multiple access control protocol named distributed synchronous reservation multiple access control protocol.in which the hidden and exposed terminal problems are solved,and the quality of service(QoS)requirements for real-time traffic are guaranteed.The protocol is founded on time division multiplex address and a different type of traffic is assigned to difierent priority,according to which a node should compete for and reserve the free slots in a different method.Moreover,there is a reservation acknowledgement process before data transmit in each reserved slot,so that the intruded terminal problem is solved.The throughput and average packets drop probability of this protocol are analyzed and simulated in a fully connected network.the results of which indicate that this protocol is efficient enough to support the real-time traffic.and it is more suitable to MANETs.