WorldWideScience

Sample records for network file access

  1. Accessing files in an internet - The Jade file system

    Science.gov (United States)

    Rao, Herman C.; Peterson, Larry L.

    1993-01-01

    Jade is a new distribution file system that provides a uniform way to name and access files in an internet environment. It makes two important contributions. First, Jade is a logical system that integrates a heterogeneous collection of existing file systems, where heterogeneous means that the underlying file systems support different file access protocols. Jade is designed under the restriction that the underlying file system may not be modified. Second, rather than providing a global name space, Jade permits each user to define a private name space. These private name spaces support two novel features: they allow multiple file systems to be mounted under one directory, and they allow one logical name space to mount other logical name spaces. A prototype of the Jade File System was implemented on Sun Workstations running Unix. It consists of interfaces to the Unix file system, the Sun Network File System, the Andrew File System, and FTP. This paper motivates Jade's design, highlights several aspects of its implementation, and illustrates applications that can take advantage of its features.

  2. Accessing files in an Internet: The Jade file system

    Science.gov (United States)

    Peterson, Larry L.; Rao, Herman C.

    1991-01-01

    Jade is a new distribution file system that provides a uniform way to name and access files in an internet environment. It makes two important contributions. First, Jade is a logical system that integrates a heterogeneous collection of existing file systems, where heterogeneous means that the underlying file systems support different file access protocols. Jade is designed under the restriction that the underlying file system may not be modified. Second, rather than providing a global name space, Jade permits each user to define a private name space. These private name spaces support two novel features: they allow multiple file systems to be mounted under one directory, and they allow one logical name space to mount other logical name spaces. A prototype of the Jade File System was implemented on Sun Workstations running Unix. It consists of interfaces to the Unix file system, the Sun Network File System, the Andrew File System, and FTP. This paper motivates Jade's design, highlights several aspects of its implementation, and illustrates applications that can take advantage of its features.

  3. 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

  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 h2>Backgroundh2> 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

  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. Accessibility in complex networks

    Science.gov (United States)

    Travençolo, B. A. N.; da F. Costa, L.

    2008-12-01

    This Letter describes a method for the quantification of the diversity of non-linear dynamics in complex networks as a consequence of self-avoiding random walks. The methodology is analyzed in the context of theoretical models and illustrated with respect to the characterization of the accessibility in urban streets.

  7. A quantum access network.

    Science.gov (United States)

    Fröhlich, Bernd; Dynes, James F; Lucamarini, Marco; Sharpe, Andrew W; Yuan, Zhiliang; Shields, Andrew J

    2013-09-05

    The theoretically proven security of quantum key distribution (QKD) could revolutionize the way in which information exchange is protected in the future. Several field tests of QKD have proven it to be a reliable technology for cryptographic key exchange and have demonstrated nodal networks of point-to-point links. However, until now no convincing answer has been given to the question of how to extend the scope of QKD beyond niche applications in dedicated high security networks. Here we introduce and experimentally demonstrate the concept of a 'quantum access network': based on simple and cost-effective telecommunication technologies, the scheme can greatly expand the number of users in quantum networks and therefore vastly broaden their appeal. We show that a high-speed single-photon detector positioned at a network node can be shared between up to 64 users for exchanging secret keys with the node, thereby significantly reducing the hardware requirements for each user added to the network. This point-to-multipoint architecture removes one of the main obstacles restricting the widespread application of QKD. It presents a viable method for realizing multi-user QKD networks with efficient use of resources, and brings QKD closer to becoming a widespread technology.

  8. Metropolitan Access Network

    Directory of Open Access Journals (Sweden)

    Slavko Šarić

    2003-11-01

    Full Text Available The optical fibre is the highest quality transmission mediumfor broadband services, and therefore the new access cablenetwork has to be realized to the greatest extent and as closeas possible to the subscriber by means of the optical fibre cables,in accordance with the possibilities of the telecommunicationoperator. The development of digital technology in commutations,supported by the increasingly powerful systems of processorcontrol, development of optical communications andtransport technologies in the framework of SDH concepts, arereflected on the access telecommunication networks of the urbanareas. Urban areas are the most profitable regions in telecommunications.In planning of urban optical networks the fact should betaken as a guideline that only a well-organised urban networkwill allow high quality of service provision of the leased cablesto the end points of business customers.Business customers have greater requirements for the networkreliability, flexibility and maintainability, for the sake ofundisturbed telecommunication traffic.The optical medium based technology- FITL (fiber in theloop, provides almost limitless upgrading of the system regardingthe transmission bandwidths, as well as adaptation to allthe future customers' requirements.Considering the increase in the price of installing the coppercables, the prices of electronics and optical components arecontinuously falling. The application of the optical medium isincreasing and becoming more cost-effective, and due to higherreliability of the optical transmission systems the maintenancecosts are reduced.

  9. 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

  10. Characteristics of file sharing and peer to peer networking | Opara ...

    African Journals Online (AJOL)

    A peer-to-peer (p2p) network allows computer hardware and software to function without the need for special server devices. While file sharing is the practice of distributing or providing access to digitally stored information, such as computer programs, multi-media (audio, video) resources, documents, or electronic books.

  11. Cytoscape file of chemical networks

    Data.gov (United States)

    U.S. Environmental Protection Agency — The maximum connectivity scores of pairwise chemical conditions summarized from Cmap results in a file with Cytoscape format (http://www.cytoscape.org/). The figures...

  12. HCUP State Emergency Department Databases (SEDD) - Restricted Access File

    Data.gov (United States)

    U.S. Department of Health & Human Services — The State Emergency Department Databases (SEDD) contain the universe of emergency department visits in participating States. Restricted access data files are...

  13. The Right of Access to Its Own File

    National Research Council Canada - National Science Library

    Gina Livioara GOGA; Georgeta MODIGA

    2015-01-01

    The right of access to its own file represents a principle of administrative law as defined in the legislation and jurisprudence of the European Union which constitutes a guarantee of the right t o defence...

  14. 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

  15. 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 ...

  16. Mission-Aware Medium Access Control in Random Access Networks

    OpenAIRE

    Park, Jaeok; Van Der Schaar, Mihaela

    2009-01-01

    We study mission-critical networking in wireless communication networks, where network users are subject to critical events such as emergencies and crises. If a critical event occurs to a user, the user needs to send necessary information for help as early as possible. However, most existing medium access control (MAC) protocols are not adequate to meet the urgent need for information transmission by users in a critical situation. In this paer, we propose a novel class of MAC protocols that u...

  17. 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

  18. 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...

  19. 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 of...

  20. 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...

  1. Scalable Lunar Surface Networks and Adaptive Orbit Access Project

    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. Quantum secured gigabit optical access networks

    Science.gov (United States)

    Fröhlich, Bernd; Dynes, James F.; Lucamarini, Marco; Sharpe, Andrew W.; Tam, Simon W.-B.; Yuan, Zhiliang; Shields, Andrew J.

    2015-12-01

    Optical access networks connect multiple endpoints to a common network node via shared fibre infrastructure. They will play a vital role to scale up the number of users in quantum key distribution (QKD) networks. However, the presence of power splitters in the commonly used passive network architecture makes successful transmission of weak quantum signals challenging. This is especially true if QKD and data signals are multiplexed in the passive network. The splitter introduces an imbalance between quantum signal and Raman noise, which can prevent the recovery of the quantum signal completely. Here we introduce a method to overcome this limitation and demonstrate coexistence of multi-user QKD and full power data traffic from a gigabit passive optical network (GPON) for the first time. The dual feeder implementation is compatible with standard GPON architectures and can support up to 128 users, highlighting that quantum protected GPON networks could be commonplace in the future.

  3. 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.

  4. 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.

  5. 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

  6. 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...

  7. Social Network Privacy via Evolving Access Control

    Science.gov (United States)

    di Crescenzo, Giovanni; Lipton, Richard J.

    We study the problem of limiting privacy loss due to data shared in a social network, where the basic underlying assumptions are that users are interested in sharing data and cannot be assumed to constantly follow appropriate privacy policies. Note that if these two assumptions do not hold, social network privacy is theoretically very easy to achieve; for instance, via some form of access control and confidentiality transformation on the data.

  8. 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......, and for the analyzed scenario it can assure synchronization on the nanosecond level, fulfilling mobile network requirements. Furthermore, mechanisms to lower delay and jitter have been identified, namely: source scheduling and preemption. An innovative source scheduling scheme which can minimize jitter has been...

  9. 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...

  10. 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...

  11. Employee and government access to personnel files: rights and requirements.

    Science.gov (United States)

    Fox, J C; Ostling, P J

    1979-01-01

    A maze of record-keeping, disclosure, and privacy statutes and regulations, with accompanying case law, have created a boom in privacy law. Employers find themselves caught in this rising tide, torn between the often conflicting requirements. The issue of access to employee files--by employees, government, and unions--is one of the most difficult issues in this complicated situation. This article discusses recent developments in the field and aims to help readers thread their way through the maze of contradictions and pitfalls confronting employers.

  12. Accessibility and delay in random temporal networks

    Science.gov (United States)

    Tajbakhsh, Shahriar Etemadi; Coon, Justin P.; Simmons, David E.

    2017-09-01

    In a wide range of complex networks, the links between the nodes are temporal and may sporadically appear and disappear. This temporality is fundamental to analyzing the formation of paths within such networks. Moreover, the presence of the links between the nodes is a random process induced by nature in many real-world networks. In this paper, we study random temporal networks at a microscopic level and formulate the probability of accessibility from a node i to a node j after a certain number of discrete time units T . While solving the original problem is computationally intractable, we provide an upper and two lower bounds on this probability for a very general case with arbitrary time-varying probabilities of the links' existence. Moreover, for a special case where the links have identical probabilities across the network at each time slot, we obtain the exact probability of accessibility between any two nodes. Finally, we discuss scenarios where the information regarding the presence and absence of links is initially available in the form of time duration (of presence or absence intervals) continuous probability distributions rather than discrete probabilities over time slots. We provide a method for transforming such distributions to discrete probabilities, which enables us to apply the given bounds in this paper to a broader range of problem settings.

  13. Security Evaluation of Wireless Network Access Points

    Directory of Open Access Journals (Sweden)

    Kalniņš Rūdolfs

    2017-05-01

    Full Text Available The paper focuses on the real-world usage of IEEE 802.11 wireless network encryption and Wi-Fi Protected Setup (WPS function. A brief history on the development of encryption methods and WPS is given. Wireless scanning of 802.11 networks in a capital city has been performed, and the results of it have been analysed. To ascertain the knowledge about the security of wireless networks of the average user, an online survey has been conducted. To test the security of encryption methods and WPS function, practical attacks against private test wireless networks have been made. The authors conclude that the safest way to set up 802.11 network with a pre-shared key is to use Wi-Fi Protected Access 2 (WPA2 encryption without support for WPS function. Statistics in Riga shows that networks are often configured otherwise and thus vulnerable to attacks. Survey results prove that respondents are not well informed regarding the security of wireless networks.

  14. Reliability monitoring of broadband access networks

    Directory of Open Access Journals (Sweden)

    Perlicki Krzysztof

    2017-06-01

    Full Text Available One of the critical issues for broadband accesss is how to test the access network infrastructure and quality of optical signal. The installation and powering up of an optical fiber access networks requires measurement techniques for verifying the link has been configured properly and that its constituent components are functioning correctly. Maintenance functions for a broadband optical access network are classified in two main categories: preventive maintenance and post-fault maintenance. The first one consists of: surveillance (to detect degradation in optical fiber components, or any other anomalous condition not preventing the signal transmission,, testing (to measure and locate any detected degradation or anomalous condition and control (fiber identification and fiber transfer to allow the testing of the link.. In turn second one consisits of: surveillance (to detect alarms or trouble reports and activate a procedure for restoration, testing (to locate the fault and/or verify the carrier performances after the restoration and remedy (fiber identification, fiber repair or fiber transfer to restore the link.

  15. Optical technologies in extended-reach access networks

    DEFF Research Database (Denmark)

    Wong, Elaine; Amaya Fernández, Ferney Orlando; Tafur Monroy, Idelfonso

    2009-01-01

    The merging of access and metro networks has been proposed as a solution to lower the unit cost of customer bandwidth. This paper reviews some of the recent advances and challenges in extended-reach optical access networks....

  16. 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.

  17. Softward-Defined Networking in Heterogeneous Radio Access Networks

    DEFF Research Database (Denmark)

    Yu, Hao

    2014-01-01

    Integrating diff erent wireless access technologies to provide users with data service will definitely result in a heterogeneous radio access network. Moving from one wireless domain to another causes traffic being switched from one interface to another. This results in a reestablishment of TCP c....... This paper provides a possible solution architecture and research direction for vertical handover problem by leveraging the concept of software - defined networking together with existing proposals....... connection due to the change of the assigned IP address. Frequent handovers may force users to perform re - logins or application restarts, which undoubtedly jeopardize the quality of experience. This vertical handover problem will not be trivial as mobility is becomin g a dominant factor in communications...

  18. 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.

  19. 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.

  20. 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.

  1. Improved Data Transmission Scheme of Network Coding Based on Access Point Optimization in VANET

    Directory of Open Access Journals (Sweden)

    Zhe Yang

    2014-01-01

    Full Text Available VANET is a hot spot of intelligent transportation researches. For vehicle users, the file sharing and content distribution through roadside access points (AP as well as the vehicular ad hoc networks (VANET have been an important complement to that cellular network. So the AP deployment is one of the key issues to improve the communication performance of VANET. In this paper, an access point optimization method is proposed based on particle swarm optimization algorithm. The transmission performances of the routing protocol with random linear network coding before and after the access point optimization are analyzed. The simulation results show the optimization model greatly affects the VANET transmission performances based on network coding, and it can enhance the delivery rate by 25% and 14% and reduce the average delay of transmission by 38% and 33%.

  2. Authentication Issues in Multi-Service Residential Access Networks

    OpenAIRE

    Rossebo, Judith; Ronan, John; Walsh, Kristian

    2003-01-01

    Multi-service residential access networks allow residential customers to choose amongst a variety of service offerings, over a range of Core Networks and subject to user requirements such as QoS, mobility, cost and availability. These issues place requirements on authentication for network access, with a need for mutual authentication of the residential gateway (RG) to the local access point (LAP). The EU-IST project TORRENT is building a testbed providing for multi-service residential access...

  3. File Access Optimization with the Lustre Filesystem at Florida CMS T2

    CERN Document Server

    Avery, P; Fu, Y; Kim, B

    2015-01-01

    The Florida CMS Tier2 center, one of the CMS Tier2 centers, has been using the Lustre filesystem for its data storage backend system since 2004. Recently, the data access pattern at our site has changed greatly due to various new access methods that include file transfers through the GridFTP servers, read access from the worker nodes, and the remote read access through the xrootd servers. In order to optimize the file access performance, we have to consider all the possible access patterns and each pattern needs to be studied separately. In this presentation, we report on our work to optimize file access with the Lustre filesystem at the Florida CMS T2 using an approach based on analyzing these access patterns.

  4. 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 ...testing real-world applications. Most importantly, our simulation serves as a template for implementing a unified MAC layer network using SDN . SDN ...is a network program with a programmable, centralized control plane.4 SDN protocols can be used to mediate access between nodes of an HN. The method

  5. Optical-router-based dynamically reconfigurable photonic access network

    NARCIS (Netherlands)

    Roy, R.

    2014-01-01

    The Broadband photonics (BBP) project under the Freeband consortium of projects investigated the design of a dynamically reconfigurable photonic access network. Access networks form a key link in ensuring optimal bandwidth to the end user without which any improvements deeper in the network in the

  6. Analysis and Comparison on Novel Sensor Network Security Access Technology

    Directory of Open Access Journals (Sweden)

    Ping LIU

    2014-01-01

    Full Text Available The article introduces against technical defects of traditional network access control system, detail NAC, NAP, UAC and TNC four kinds of new network security access technology, and this article analyzes and compares them. Security framework for wireless sensor networks SPINS defines the mechanism and algorithm of complete and effective in confidentiality, point-to-point message authentication, integrity, authentication, broadcast authentication.

  7. Models of network access using feedback fluid queues

    NARCIS (Netherlands)

    Mandjes, M.R.H.; Mitra, Debasis; Scheinhardt, Willem R.W.

    At the access to networks, in contrast to the core, distances and feedback delays, as well as link capacities are small, which has network engineering implications that are investigated in this paper. We consider a single point in the access network which multiplexes several bursty users. The users

  8. Models of network access using feedback fluid queues

    NARCIS (Netherlands)

    M.R.H. Mandjes (Michel); D. Mitra; W.R.W. Scheinhardt (Werner)

    2002-01-01

    htmlabstractAt the access to networks, in contrast to the core, distances and feedback delay s, as well as link capacities are small, which has network engineering implications that are investigated in this paper. We consider a single point in the access network which multiplexes several bursty

  9. 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......Mobile operators are moving towards sharing network capacity in order to reduce capital and operational expenditures, while meeting the increasing demand for mobile broadband data services. Radio access network sharing is a promising technique that leads to reduced number of physical base station...... 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...

  10. 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

    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......, network delay characterization) and specific requirements on mismatch probability, traffic overhead, and access delay. Finally, the analysis is applied to the use-case of context-sensitive service discovery....

  11. Service delivery aspects in a reconfigurable photonic access network

    NARCIS (Netherlands)

    Roy, R.; Manhoudt, Gert; van Etten, Wim

    2008-01-01

    We discuss service delivery aspects in a reconfigurable photonic access network. The network is viewed as a stack of logical PONs in which a DWDM overlay is used over TDM PONs operating in their native format. The use of optical routers in the network allows for a dynamic change in the network

  12. Ocean Surface Topography Mission (OSTM) /Jason-2: Ancillary Files (NODC Accession 0044982)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains the data descriptions for the OSTM/Jason-2 Ancillary data files, which is served through the NOAA/NESDIS Comprehensive Large Array-data...

  13. Ocean Surface Topography Mission (OSTM) /Jason-2: Auxiliary Files (NODC Accession 0044983)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains the data descriptions for the OSTM/Jason-2 Auxiliary data files, which is served through the NOAA/NESDIS Comprehensive Large Array-data...

  14. Broadband Access Network Planning Optimization Considering Real Copper Cable Lengths

    Science.gov (United States)

    Peternel, Blaž Kos, Andrej

    Broadband access network planning strategies with techno-economic calculations are important topics, when optimal broadband network deployments are considered. This paper analyzes optimal deployment combination of digital subscriber line technologies (xDSL) and fiber to the home technologies (FTTx), following different user bandwidth demand scenarios. For this reason, optimal placement of remote digital subscriber line multiplexer (RDSLAM) is examined. Furthermore, the article also discusses the economy of investments, depending on certain investment threshold and the reach of different xDSL technologies. Finally, the difference between broadband network deployment in a characteristic urban and rural area in Republic of Slovenia, in terms of required optical cable dig length per household is shown. A tree structure network model of a traditional copper access network is introduced. A dynamic programming logic, with recursion as a basis of a tree structure examination and evaluation of optimal network elements placement is used. The tree structure network model considers several real network parameters (e. g.: copper cable lengths, user coordinates, node coordinates). The main input for the optimization is a local loop distance between each user and a candidate node for RDSLAM placement. Modelling of copper access networks with a tree structure makes new extensions in planning optimization of broadband access networks. Optimization of network elements placement has direct influence on efficiency and profitability of broadband access telecommunication networks.

  15. 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...

  16. Access network evolution: optical fibre to the subscribers and impact on the metropolitan and home networks

    Science.gov (United States)

    Chanclou, P.; Belfqih, Z.; Charbonnier, B.; Duong, T.; Frank, F.; Genay, N.; Huchard, M.; Guignard, P.; Guillo, L.; Landousies, B.; Pizzinat, A.; Ramanitra, H.; Saliou, F.; Durel, S.; Urvoas, P.; Ouzzif, M.; Le Masson, J.

    2008-11-01

    This article describes broadband optical access network evolution including high speed interfaces for fixed and mobile services. The impact of network access evolution on network architecture and transmission equipment localization on the metropolitan network is also mentioned. Some technical challenges are also discussed, namely concerning the optical extended budget, as well as the impact of access evolution on the metropolitan network. The access bit rate evolution has also an impact on the home network by the necessity of offering connectivity to customers at 1 Gbit/s, for example, over plastic optical fibre. To cite this article: P. Chanclou et al., C. R. Physique 9 (2008).

  17. 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.

  18. File Detection On Network Traffic Using Approximate Matching

    Directory of Open Access Journals (Sweden)

    Frank Breitinger

    2014-09-01

    Full Text Available In recent years, Internet technologies changed enormously and allow faster Internet connections, higher data rates and mobile usage. Hence, it is possible to send huge amounts of data / files easily which is often used by insiders or attackers to steal intellectual property. As a consequence, data leakage prevention systems (DLPS have been developed which analyze network traffic and alert in case of a data leak. Although the overall concepts of the detection techniques are known, the systems are mostly closed and commercial.Within this paper we present a new technique for network trac analysis based on approximate matching (a.k.a fuzzy hashing which is very common in digital forensics to correlate similar files. This paper demonstrates how to optimize and apply them on single network packets. Our contribution is a straightforward concept which does not need a comprehensive conguration: hash the file and store the digest in the database. Within our experiments we obtained false positive rates between 10-4 and 10-5 and an algorithm throughput of over 650 Mbit/s.

  19. 28 CFR 513.41 - Inmate access to Inmate Central File in connection with parole hearings.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Inmate access to Inmate Central File in connection with parole hearings. 513.41 Section 513.41 Judicial Administration BUREAU OF PRISONS, DEPARTMENT OF JUSTICE GENERAL MANAGEMENT AND ADMINISTRATION ACCESS TO RECORDS Release of Information Inmate Requests to Institution for Information § 51...

  20. The impact of wireless device access on content delivery networks

    OpenAIRE

    Denney, Justin; Race, Nicholas

    2003-01-01

    Content delivery network architectures are initiatives designed to support the effective delivery of continuous and discrete media to end-users. Mobile devices are now capable of exploiting services such as content delivery, but with the protocols governing the content delivery networks designed for wired networked topologies; an assessment of the impact of mobile devices on the network has never been undertaken. Wireless devices access causes significant issues in the ability of the media tr...

  1. Access Network Selection Based on Fuzzy Logic and Genetic Algorithms

    Directory of Open Access Journals (Sweden)

    Mohammed Alkhawlani

    2008-01-01

    Full Text Available In the next generation of heterogeneous wireless networks (HWNs, a large number of different radio access technologies (RATs will be integrated into a common network. In this type of networks, selecting the most optimal and promising access network (AN is an important consideration for overall networks stability, resource utilization, user satisfaction, and quality of service (QoS provisioning. This paper proposes a general scheme to solve the access network selection (ANS problem in the HWN. The proposed scheme has been used to present and design a general multicriteria software assistant (SA that can consider the user, operator, and/or the QoS view points. Combined fuzzy logic (FL and genetic algorithms (GAs have been used to give the proposed scheme the required scalability, flexibility, and simplicity. The simulation results show that the proposed scheme and SA have better and more robust performance over the random-based selection.

  2. Analysis of Social Networks Extracted from Log Files

    Science.gov (United States)

    Slaninová, Kateřina; Martinovič, Jan; Dráždilová, Pavla; Obadi, Gamila; Snášel, Václav

    Each chapter should be preceded by an abstract (10-15 lines long) that summarizes the content. The abstract will appear online at http://www.SpringerLink.com and be available with unrestricted access. This allows unregistered users to read the abstract as a teaser for the complete chapter. As a general rule the abstracts will not appear in the printed version of your book unless it is the style of your particular book or that of the series to which your book belongs. Please use the "starred" version of the new Springer abstract command for typesetting the text of the online abstracts (cf. source file of this chapter template abstract) and include them with the source files of your manuscript. Use the plain abstract command if the abstract is also to appear in the printed version of the book.

  3. Designing Broadband Access Networks with Triple Redundancy

    DEFF Research Database (Denmark)

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

    2005-01-01

    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...... without compromising line independency, and it can be implemented stepwise, the first step being based on a simple ring/tree topology. The double ring is used for the distribution network, ensuring 3-connectivity and making it feasible to use for connecting the base stations of the wireless network...

  4. 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....

  5. 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.

  6. Open Data poster for Open Access Week - AI file

    OpenAIRE

    Briney, Kristin

    2013-01-01

    Adobe Illustrator (.ai) version of the Open Data/Open Access week poster.   PDF version: http://figshare.com/articles/Open_Data_Poster_for_Open_Access_Week/828595 Combined fileset here: http://figshare.com/articles/Open_Data_Poster_for_Open_Access_Week/828597

  7. Open Data Poster for Open Access Week - PDF file

    OpenAIRE

    Briney, Kristin

    2013-01-01

    .pdf version of the Open Data/Open Access Week poster.   Illustrator version: http://figshare.com/articles/Open_Data_poster_for_Open_Access_Week/828596 Combined fileset here: http://figshare.com/articles/Open_Data_Poster_for_Open_Access_Week/828597

  8. 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

  9. 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...

  10. Modeling of Bandwidth Aggregation over Heterogeneous Wireless Access Networks

    DEFF Research Database (Denmark)

    Popovska Avramova, Andrijana; Dittmann, Lars

    2012-01-01

    Motivated by the multihomming capability of the mobile devices and the fact that the heterogeneous wireless access networks overlap in coverage, mobile operators are looking for solutions that will benefit by simultaneous use of the available multiple access interfaces. Multipath or multilink...... applications. The analysis is performed on a multipath model developed with OPNET Modeler, which is an advanced research tool that supports modeling and integration of various kinds of built-in networks....

  11. NAFFS: network attached flash file system for cloud storage on portable consumer electronics

    Science.gov (United States)

    Han, Lin; Huang, Hao; Xie, Changsheng

    Cloud storage technology has become a research hotspot in recent years, while the existing cloud storage services are mainly designed for data storage needs with stable high speed Internet connection. Mobile Internet connections are often unstable and the speed is relatively low. These native features of mobile Internet limit the use of cloud storage in portable consumer electronics. The Network Attached Flash File System (NAFFS) presented the idea of taking the portable device built-in NAND flash memory as the front-end cache of virtualized cloud storage device. Modern portable devices with Internet connection have built-in more than 1GB NAND Flash, which is quite enough for daily data storage. The data transfer rate of NAND flash device is much higher than mobile Internet connections[1], and its non-volatile feature makes it very suitable as the cache device of Internet cloud storage on portable device, which often have unstable power supply and intermittent Internet connection. In the present work, NAFFS is evaluated with several benchmarks, and its performance is compared with traditional network attached file systems, such as NFS. Our evaluation results indicate that the NAFFS achieves an average accessing speed of 3.38MB/s, which is about 3 times faster than directly accessing cloud storage by mobile Internet connection, and offers a more stable interface than that of directly using cloud storage API. Unstable Internet connection and sudden power off condition are tolerable, and no data in cache will be lost in such situation.

  12. Network accessibility & the evoluation of urban employment.

    Science.gov (United States)

    2011-06-01

    This research examines the impact of accessibility on the growth of employment centers in the : Los Angeles Region between 1980 and 2000. There is extensive empirical documentation of : polycentricity the presence of multiple concentrations of em...

  13. 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...

  14. Approximate Networking for Universal Internet Access

    National Research Council Canada - National Science Library

    Junaid Qadir; Arjuna Sathiaseelan; Umar Bin Farooq; Muhammad Usama; Muhammad Ali Imran; Muhammad Shafique

    2017-01-01

    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...

  15. 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.

  16. Analytical Modeling of Medium Access Control Protocols in Wireless Networks

    Science.gov (United States)

    2006-03-01

    Imperatives and chal- lenges. Ad Hoc Networks, 1(1):13–64, July 2003. [28] I. Chlamtac and A. Faragó. Making transmission schedules immune to topology changes...P. Karn. MACA - a new channel access method for packet radio. In ARRL/CRRL Amateur Radio 9th Computer Networking Conference, pages 134–140, 1990

  17. Robust and Flexible Wavelength Division Multiplexed Optical Access Networks

    DEFF Research Database (Denmark)

    Wagner, Christoph; Eiselt, Michael; Grobe, Klaus

    Future wavelength division multiplexed (WDM) access networks should be as flexible as possible. One flexibility is port wavelength-agnosticism at the optical network unit (ONU) interface, achieved via tunable laser. At the same time such systems needs to be robust against crosstalk impairments...

  18. Police, perversion and privacy: managing access to confidential files ...

    African Journals Online (AJOL)

    Such issues are addressed in the Promotion of Access to Information Act (PAIA), but certain ambiguities are open to interpretation, a matter taken up by the National Archives. Both legal and ethical considerations are put to the test when granting access to records where personal privacy rights may be infringed upon.

  19. Greening radio access networks using distributed base station architectures

    DEFF Research Database (Denmark)

    Kardaras, Georgios; Soler, José; Dittmann, Lars

    2010-01-01

    . 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...

  20. A standard multidimensional, easy-access data file structure for Apple II computers.

    Science.gov (United States)

    Waterborg, J H; Harrington, R E

    1986-12-01

    A random access file structure was designed for Apple II microcomputers that allows data storage of more than 65,500 data values at 170 per Kbyte with a dynamic range of nearly 5 orders of magnitude. All or part of the data are easily accessible from BASIC under ProDOS operating conditions. The file structure accommodates single or multiple data sets in a single data file. Data values within a file with one set of data may interrelate by equal spacing along a second coordinate, such as time or space. Multiple data sets in a file can be independent, parallel or interdependent. Each interdependent data set defines the position of a data point along its coordinate in a two- or multidimensional registration system. The lowest and highest values of each data set are separately recorded to allow easy manipulation of even part of the data, e.g. for graphical presentation. The possibility of storing large numbers of data values in a single file facilitates high-resolution recording of events and simple mathematical manipulation.

  1. Dynamic file-access characteristics of a production parallel scientific workload

    Science.gov (United States)

    Kotz, David; Nieuwejaar, Nils

    1994-01-01

    Multiprocessors have permitted astounding increases in computational performance, but many cannot meet the intense I/O requirements of some scientific applications. An important component of any solution to this I/O bottleneck is a parallel file system that can provide high-bandwidth access to tremendous amounts of data in parallel to hundreds or thousands of processors. Most successful systems are based on a solid understanding of the expected workload, but thus far there have been no comprehensive workload characterizations of multiprocessor file systems. This paper presents the results of a three week tracing study in which all file-related activity on a massively parallel computer was recorded. Our instrumentation differs from previous efforts in that it collects information about every I/O request and about the mix of jobs running in a production environment. We also present the results of a trace-driven caching simulation and recommendations for designers of multiprocessor file systems.

  2. 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...

  3. 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...

  4. Feasibility of using existing open access networks to support the harmonization of open access

    OpenAIRE

    Linde, Peter; Wessels, Bridgette; Smallwood, Rod; Price, Lada; Noorman, Merel; Wyatt, Sally; Sondervan, Jeroen

    2015-01-01

    In this report we identify and assess different options for bringing together and mobilizing relevant stakeholders in the open access arena. This builds on previous work done in the RECODE project about the open access stakeholder ecosystem, the barriers and the enablers for open access to research data as well as on the RECODE overarching policy recommendations set out in the RECODE work package 5. We have identified a sample of existing networks and organizations to determine whether they a...

  5. #DDOD Use Case: Access to Medicare Part D Drug Event File (PDE) for cost transparency

    Data.gov (United States)

    U.S. Department of Health & Human Services — SUMMARY DDOD use case to request access to Medicare Part D Drug Event File (PDE) for cost transparency to pharmacies and patients. WHAT IS A USE CASE? A “Use Case”...

  6. ACAFD: Secure and Scalable Access Control with Assured File Deletion for Outsourced Data in Cloud

    Directory of Open Access Journals (Sweden)

    Sudha Senthilkumar

    2014-11-01

    Full Text Available Cloud storage has emerged as a popular paradigm to outsource data to third party and share it with the collaborators. While this new paradigm enables users to outsource their sensitive data and reduces data management costs, it brings forth the new challenges to the user to keep their data secure. Data storage security and access control in the cloud is one of the challenging ongoing research works to alleviate the data leakage problem from unauthorized users. Existing solutions that use pure cryptographic techniques suffers from heavy computation work with respect to key management and key distribution.  Attribute based encryption is an alternative solution that map the user access structure with the data file attributes to control the data access. However any of the existing schemes doesn’t address the access control with assured deletion of the files upon revocation of user access. This article addresses this open issue using a trusted authority that manages the access control list and takes care of key management and key distribution and file deletion upon user revocation. The prototype of model has been presented and analyzed the security features over existing scheme.

  7. Ever enrolled Medicare population estimates from the MCBS Access to Care files.

    Science.gov (United States)

    Petroski, Jason; Ferraro, David; Chu, Adam

    2014-01-01

    The Medicare Current Beneficiary Survey's (MCBS) Access to Care (ATC) file is designed to provide timely access to information on the Medicare population, yet because of the survey's complex sampling design and expedited processing it is difficult to use the file to make both "always-enrolled" and "ever-enrolled" estimates on the Medicare population. In this study, we describe the ATC file and sample design, and we evaluate and review various alternatives for producing "ever-enrolled" estimates. We created "ever enrolled" estimates for key variables in the MCBS using three separate approaches. We tested differences between the alternative approaches for statistical significance and show the relative magnitude of difference between approaches. Even when estimates derived from the different approaches were statistically different, the magnitude of the difference was often sufficiently small so as to result in little practical difference among the alternate approaches. However, when considering more than just the estimation method, there are advantages to using certain approaches over others. There are several plausible approaches to achieving "ever-enrolled" estimates in the MCBS ATC file; however, the most straightforward approach appears to be implementation and usage of a new set of "ever-enrolled" weights for this file.

  8. An evaluation of Access Tier local area network switches.

    Energy Technology Data Exchange (ETDEWEB)

    Eldridge, John M.; Olsberg, Ronald R.

    2004-06-01

    This reports tabulates the Test and Evaluation results of the Access Class Switch tests conducted by members of Department 9336. About 15 switches were reviewed for use in the enterprise network as access tier switches as defined in a three tier architecture. The Access Switch Tier has several functions including: aggregate customer desktop ports, preserve and apply QoS tags, provide switched LAN access, provide VLAN assignment, as well as others. The typical switch size is 48 or less user ports. The evaluation team reviewed network switch evaluation reports from the Tolly Group as well as other sources. We then used these reports as a starting point to identify particular switches for evaluation. In general we reviewed the products of dominant equipment manufacturers. Also, based on architectural design requirements, the majority of the switches tested were of relatively small monolithic unit variety.

  9. How social network heterogeneity facilitates lexical access and lexical prediction.

    Science.gov (United States)

    Lev-Ari, Shiri; Shao, Zeshu

    2017-04-01

    People learn language from their social environment. As individuals differ in their social networks, they might be exposed to input with different lexical distributions, and these might influence their linguistic representations and lexical choices. In this article we test the relation between linguistic performance and 3 social network properties that should influence input variability, namely, network size, network heterogeneity, and network density. In particular, we examine how these social network properties influence lexical prediction, lexical access, and lexical use. To do so, in Study 1, participants predicted how people of different ages would name pictures, and in Study 2 participants named the pictures themselves. In both studies, we examined how participants' social network properties related to their performance. In Study 3, we ran simulations on norms we collected to see how age variability in one's network influences the distribution of different names in the input. In all studies, network age heterogeneity influenced performance leading to better prediction, faster response times for difficult-to-name items, and less entropy in input distribution. These results suggest that individual differences in social network properties can influence linguistic behavior. Specifically, they show that having a more heterogeneous network is associated with better performance. These results also show that the same factors influence lexical prediction and lexical production, suggesting the two might be related.

  10. 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 i......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...

  11. Outward Accessibility in Urban Street Networks: Characterization and Improvements

    OpenAIRE

    Travençolo, Bruno Augusto Nassif; Costa, Luciano da Fontoura

    2008-01-01

    The dynamics of transportation through towns and cities is strongly affected by the topology of the connections and routes. The current work describes an approach combining complex networks and self-avoiding random walk dynamics in order to quantify in objective and accurate manner, along a range of spatial scales, the accessibility of places in towns and cities. The transition probabilities are estimated for several lengths of the walks and used to calculate the outward accessibility of each...

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    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...... of this approach for a constraint communication networks of the smart grid and compared three general data access mechanisms, namely, push, pull and event-based....

  13. A Survey of Access Control Models in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Htoo Aung Maw

    2014-06-01

    Full Text Available Wireless sensor networks (WSNs have attracted considerable interest in the research community, because of their wide range of applications. However, due to the distributed nature of WSNs and their deployment in remote areas, these networks are vulnerable to numerous security threats that can adversely affect their proper functioning. Resource constraints in sensor nodes mean that security mechanisms with a large overhead of computation and communication are impractical to use in WSNs; security in sensor networks is, therefore, a challenge. Access control is a critical security service that offers the appropriate access privileges to legitimate users and prevents illegitimate users from unauthorized access. However, access control has not received much attention in the context of WSNs. This paper provides an overview of security threats and attacks, outlines the security requirements and presents a state-of-the-art survey on access control models, including a comparison and evaluation based on their characteristics in WSNs. Potential challenging issues for access control schemes in WSNs are also discussed.

  14. Proposal of using wireless optical mesh networks and integrated VDSL for broadband access networks

    Science.gov (United States)

    Zhang, Jinlong

    2001-11-01

    The proposal addresses the wireless optical broadband access networks architecture by deploying mesh network structure, which could be the alternatives to FTTx (home or node, etc) architecture. Instead of fiber used as the transmission medium in the distribution plant, here we suggest to use the free space optic links to construct the optical mesh network. The practical connections are depending on the services provided. For Video-on-Demand (VoD) service, the final connection could use twisted pair by integrated VDSL technology. The distributed bandwidth can reach 25-32 Mbps per end user. In this paper we give some comments for designing a broadband access network using optical mesh network structure. It includes the traffic estimation, transmission network design and access node design suggestions.

  15. Secure-Network-Coding-Based File Sharing via Device-to-Device Communication

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2017-01-01

    Full Text Available In order to increase the efficiency and security of file sharing in the next-generation networks, this paper proposes a large scale file sharing scheme based on secure network coding via device-to-device (D2D communication. In our scheme, when a user needs to share data with others in the same area, the source node and all the intermediate nodes need to perform secure network coding operation before forwarding the received data. This process continues until all the mobile devices in the networks successfully recover the original file. The experimental results show that secure network coding is very feasible and suitable for such file sharing. Moreover, the sharing efficiency and security outperform traditional replication-based sharing scheme.

  16. 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.

  17. 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.

  18. 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.

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    This paper defines the requirements for cooperation of heterogeneous radio access networks (RANs) and proposes a novel radio resource management (RRM) framework for support of mobility and quality of service (QoS) in a heterogeneous communication environment comprising IMT-Advanced and legacy...

  20. Random Access with Physical-layer Network Coding

    NARCIS (Netherlands)

    Goseling, J.; Gastpar, M.C.; Weber, J.H.

    2013-01-01

    Leveraging recent progress in compute-and-forward we propose an approach to random access that is based on physical-layer network coding: When packets collide, it is possible to recover a linear combination of the packets at the receiver. Over many rounds of transmission, the receiver can thus

  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...

  2. 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

    In this paper the authors present the challenges for enabling Security Policies Management and subsequent Ubiquitous Access Control on the Personal Network (PN) environment. A solution based on Security Profiles is proposed, supporting both partially distributed architectures-having in this case...

  3. 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

  4. 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...

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

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

    This project provides support for the Knowledge Access in Rural Interconnected Areas Network (KariaNet). Phases I and II ran from 2004 to 2013. The goal of Phase III is to mainstream knowledge management and sharing on local food systems to enable rural and agricultural development professionals to improve project ...

  6. 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 amplitudep...... wired-wireless access networks....... 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...... to be utilized for multiple service allocation to different users. MIMO multiplexing techniques with OFDM provides the scalability in increasing spectral efficiency and bit rates for RoF systems. High dimensional CAP and MIMO multiplexing techniques are two promising solutions for supporting wired and hybrid...

  7. 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

    This paper advocates for a new Medium Access Control (MAC) strategy for wireless meshed networks by identifying overload scenarios in order to provide additional channel access priority to the relay. The key behind our MAC protocol is that the relay will adjust its back off window size according...... 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...... classical forwarding when both systems implement the improved MAC. However, our measurement results show an even larger gain for network coding, namely, up to 65 % over forwarding, as it copes better with channel losses under high load scenarios....

  8. Alternatives for Monitoring and Limiting Network Access to Students in Network-Connected Classrooms

    Science.gov (United States)

    Almeroth, Kevin; Zhang, Hangjin

    2013-01-01

    With the advent of laptop computers and network technology, many classrooms are now being equipped with Internet connections, either through wired connections or wireless infrastructure. Internet access provides students an additional source from which to obtain course-related information. However, constant access to the Internet can be a…

  9. An Efficient Format for Nearly Constant-Time Access to Arbitrary Time Intervals in Large Trace Files

    Directory of Open Access Journals (Sweden)

    Anthony Chan

    2008-01-01

    Full Text Available A powerful method to aid in understanding the performance of parallel applications uses log or trace files containing time-stamped events and states (pairs of events. These trace files can be very large, often hundreds or even thousands of megabytes. Because of the cost of accessing and displaying such files, other methods are often used that reduce the size of the tracefiles at the cost of sacrificing detail or other information. This paper describes a hierarchical trace file format that provides for display of an arbitrary time window in a time independent of the total size of the file and roughly proportional to the number of events within the time window. This format eliminates the need to sacrifice data to achieve a smaller trace file size (since storage is inexpensive, it is necessary only to make efficient use of bandwidth to that storage. The format can be used to organize a trace file or to create a separate file of annotations that may be used with conventional trace files. We present an analysis of the time to access all of the events relevant to an interval of time and we describe experiments demonstrating the performance of this file format.

  10. Text Classification: Classifying Plain Source Files with Neural Network

    Directory of Open Access Journals (Sweden)

    Jaromir Veber

    2010-10-01

    Full Text Available The automated text file categorization has an important place in computer engineering, particularly in the process called data management automation. A lot has been written about text classification and the methods allowing classification of these files are well known. Unfortunately most studies are theoretical and for practical implementation more research is needed. I decided to contribute with a research focused on creating of a classifier for different kinds of programs (source files, scripts…. This paper will describe practical implementation of the classifier for text files depending on file content.

  11. An Efficient Channel Access Scheme for Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Syed Asad Hussain

    2017-01-01

    Full Text Available Vehicular Ad Hoc Networks (VANETs are getting more popularity due to the potential Intelligent Transport Systems (ITS technology. It provides many efficient network services such as safety warnings (collision warning, entertainment (video and voice, maps based guidance, and emergency information. VANETs most commonly use Road Side Units (RSUs and Vehicle-to-Vehicle (V2V referred to as Vehicle-to-Infrastructure (V2I mode for data accessing. IEEE 802.11p standard which was originally designed for Wireless Local Area Networks (WLANs is modified to address such type of communication. However, IEEE 802.11p uses Distributed Coordination Function (DCF for communication between wireless nodes. Therefore, it does not perform well for high mobility networks such as VANETs. Moreover, in RSU mode timely provision of data/services under high density of vehicles is challenging. In this paper, we propose a RSU-based efficient channel access scheme for VANETs under high traffic and mobility. In the proposed scheme, the contention window is dynamically varied according to the times (deadlines the vehicles are going to leave the RSU range. The vehicles with shorter time deadlines are served first and vice versa. Simulation is performed by using the Network Simulator (NS-3 v. 3.6. The simulation results show that the proposed scheme performs better in terms of throughput, backoff rate, RSU response time, and fairness.

  12. Preferred access in packet-switching radio networks

    Science.gov (United States)

    Shacham, N.

    Channel-access protocols that provide prioritized access to a common channel in a packet switching network are considered. The elements of such protocols are discussed and a specific protocol that integrates two types of packets is proposed. A probabilistic model of the protocol is presented, and its analysis yields the throughput-delay characteristics of the two classes and the interaction between them. The model is analyzed by a method similar to the one used in priority queues; this method allows consideration of each class separately, thus reducing the computational effort substantially.

  13. 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.

  14. A spontaneous ad hoc network to share www access

    OpenAIRE

    Lloret Jaime; Garcia Miguel; Peñalver Lourdes; Lacuesta Raquel

    2010-01-01

    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 network...

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    is used for safety and security monitoring purposes. In this paper, we evaluate different access strategies to remote dynamic information and compare between achieving information reliability (mismatch probability) and the associated power consumption. Lastly, based on the models, we propose an adaptive......Accessing information remotely to dynamically changing information elements cannot be avoided and has become a required functionality for various network services. Most applications require up-to-date information which is reliable and accurate. The information reliability in terms of using correct...... 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...

  16. A Network Access Control Framework for 6LoWPAN Networks

    Science.gov (United States)

    Oliveira, Luís M. L.; Rodrigues, Joel J. P. C.; de Sousa, Amaro F.; Lloret, Jaime

    2013-01-01

    Low power over wireless personal area networks (LoWPAN), in particular wireless sensor networks, represent an emerging technology with high potential to be employed in critical situations like security surveillance, battlefields, smart-grids, and in e-health applications. The support of security services in LoWPAN is considered a challenge. First, this type of networks is usually deployed in unattended environments, making them vulnerable to security attacks. Second, the constraints inherent to LoWPAN, such as scarce resources and limited battery capacity, impose a careful planning on how and where the security services should be deployed. Besides protecting the network from some well-known threats, it is important that security mechanisms be able to withstand attacks that have not been identified before. One way of reaching this goal is to control, at the network access level, which nodes can be attached to the network and to enforce their security compliance. This paper presents a network access security framework that can be used to control the nodes that have access to the network, based on administrative approval, and to enforce security compliance to the authorized nodes. PMID:23334610

  17. 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.

  18. 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...

  19. 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.

  20. 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).

  1. 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.

  2. A Fine-Grained Data Access Control System in Wireless Sensor Network

    National Research Council Canada - National Science Library

    Boniface K. Alese; Sylvester O. Olatunji; Oluwatoyin C. Agbonifo; Aderonke F. Thompson

    2015-01-01

    .... 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...

  3. Supporting Dynamic Spectrum Access in Heterogeneous LTE+ Networks

    Energy Technology Data Exchange (ETDEWEB)

    Luiz A. DaSilva; Ryan E. Irwin; Mike Benonis

    2012-08-01

    As early as 2014, mobile network operators’ spectral capac- ity is expected to be overwhelmed by the demand brought on by new devices and applications. With Long Term Evo- lution Advanced (LTE+) networks likely as the future one world 4G standard, network operators may need to deploy a Dynamic Spectrum Access (DSA) overlay in Heterogeneous Networks (HetNets) to extend coverage, increase spectrum efficiency, and increase the capacity of these networks. In this paper, we propose three new management frameworks for DSA in an LTE+ HetNet: Spectrum Accountability Client, Cell Spectrum Management, and Domain Spectrum Man- agement. For these spectrum management frameworks, we define protocol interfaces and operational signaling scenar- ios to support cooperative sensing, spectrum lease manage- ment, and alarm scenarios for rule adjustment. We also quan- tify, through integer programs, the benefits of using DSA in an LTE+ HetNet, that can opportunistically reuse vacant TV and GSM spectrum. Using integer programs, we consider a topology using Geographic Information System data from the Blacksburg, VA metro area to assess the realistic benefits of DSA in an LTE+ HetNet.

  4. Performance of SON for RSRP-based LTE/WLAN access network selection

    NARCIS (Netherlands)

    Kovács, I.Z.; Laselva, D.; Michaelsen, P.H.; Wang, Y.; Djapic, R.; Spaey, K.

    2014-01-01

    Carrier-grade Wireless Local Area Network (WLAN) is becoming an important complementary system to cellular networks for Mobile Network Operators (MNOs). Network controlled access network selection between cellular and WLAN is an essential functionality to optimize network performance and user

  5. 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

  6. 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.

  7. 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.

  8. Implementasi Network Attached Storage (NAS) Menggunakan NAS4Free untuk Media Backup File

    OpenAIRE

    Kartika Imam Santoso; Muhamad Abdul Muin

    2016-01-01

    STMIK Bina Patria Magelang adalah sekolah tinggi yang berada di jalan Raden Saleh No.2 Magelang, yang membidangi dalam ilmu komputer. STMIK Bina Patria mempunyai file–file pekerjaan yang sangat penting dan privasi, sehingga perlu untuk adanya sistem yang berguna untuk backup file. Network Attached Storage (NAS) adalah sebuah server dengan sistem operasi yang dikhususkan untuk melayani kebutuhan berkas data. NAS dapat berbentuk perangkat yang siap pakai atau berupa sebuah software yang akan di...

  9. Amplified CWDM-based Next Generation Broadband Access Networks

    Science.gov (United States)

    Peiris, Sasanthi Chamarika

    The explosive growth of both fixed and mobile data-centric traffic along with the inevitable trend towards all-IP/Ethernet transport protocols and packet switched networks will ultimately lead to an all-packet-based converged fixed-mobile optical transport network from the core all the way out to the access network. To address the increasing capacity and speed requirements in the access networks, Wavelength-Division Multiplexed (WDM) and/or Coarse WDM (CWDM)-based Passive Optical Networks (PONs) are expected to emerge as the next-generation optical access infrastructures. However, due to several techno-economic hurdles, CWDM-PONs are still considered an expensive solution and have not yet made any significant inroads into the current access area. One of the key technology hurdles is the scalability of the CWDM-based PONs. Passive component optical insertion losses limit the reach of the network or the number of served optical network units (ONUs). In the recent years, optical amplified CWDM approaches have emerged and new designs of optical amplifiers have been proposed and demonstrated. The critical design parameter for these amplifiers is the very wide optical amplification bandwidth (e.g., 340 nm combined for both directions). The objective of this PhD dissertation work is first to engineer ring and tree-ring based PON architectures that can achieve longer unamplified PON reach and/or provide service to a greater number of ONUs and customers. Secondly is to develop new novel optical amplifier schemes to further address the scalability limitation of the CWDM-based PONs. Specifically, this work proposes and develops novel ultra wide-band hybrid Raman-Optical parametric amplifier (HROPA) schemes that operate over nearly the entire specified CWDM band to provide 340 nm bidirectional optical gain bandwidth over the amplified PON's downstream and upstream CWDM wavelength bands (about 170 nm in each direction). The performance of the proposed HROPA schemes is assessed

  10. 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.

  11. Approaches in highly parameterized inversion-PESTCommander, a graphical user interface for file and run management across networks

    Science.gov (United States)

    Karanovic, Marinko; Muffels, Christopher T.; Tonkin, Matthew J.; Hunt, Randall J.

    2012-01-01

    Models of environmental systems have become increasingly complex, incorporating increasingly large numbers of parameters in an effort to represent physical processes on a scale approaching that at which they occur in nature. Consequently, the inverse problem of parameter estimation (specifically, model calibration) and subsequent uncertainty analysis have become increasingly computation-intensive endeavors. Fortunately, advances in computing have made computational power equivalent to that of dozens to hundreds of desktop computers accessible through a variety of alternate means: modelers have various possibilities, ranging from traditional Local Area Networks (LANs) to cloud computing. Commonly used parameter estimation software is well suited to take advantage of the availability of such increased computing power. Unfortunately, logistical issues become increasingly important as an increasing number and variety of computers are brought to bear on the inverse problem. To facilitate efficient access to disparate computer resources, the PESTCommander program documented herein has been developed to provide a Graphical User Interface (GUI) that facilitates the management of model files ("file management") and remote launching and termination of "slave" computers across a distributed network of computers ("run management"). In version 1.0 described here, PESTCommander can access and ascertain resources across traditional Windows LANs: however, the architecture of PESTCommander has been developed with the intent that future releases will be able to access computing resources (1) via trusted domains established in Wide Area Networks (WANs) in multiple remote locations and (2) via heterogeneous networks of Windows- and Unix-based operating systems. The design of PESTCommander also makes it suitable for extension to other computational resources, such as those that are available via cloud computing. Version 1.0 of PESTCommander was developed primarily to work with the

  12. A Spontaneous Ad Hoc Network to Share WWW Access

    Directory of Open Access Journals (Sweden)

    Raquel Lacuesta

    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.

  13. Design, Implementation and Optimization of Innovative Internet Access Networks, based on Fog Computing and Software Defined Networking

    OpenAIRE

    Iotti, Nicola

    2017-01-01

    1. DESIGN In this dissertation we introduce a new approach to Internet access networks in public spaces, such as Wi-Fi network commonly known as Hotspot, based on Fog Computing (or Edge Computing), Software Defined Networking (SDN) and the deployment of Virtual Machines (VM) and Linux containers, on the edge of the network. In this vision we deploy specialized network elements, called Fog Nodes, on the edge of the network, able to virtualize the physical infrastructure and expose APIs to e...

  14. 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

  15. Design of a of a survivable multi-wavelength photonic access network

    NARCIS (Netherlands)

    Roy, R.; van Etten, Wim

    2007-01-01

    This paper investigates the design of protection schemes in an extended access network. The network is modeled as a stack of quasi independent logical passive optical networks(PONs), each operating the IEEE Ethernet passive optical networks (EPON) protocol. The dynamics of the network operation when

  16. 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

  17. 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...

  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. 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...

  20. 47 CFR 51.311 - Nondiscriminatory access to unbundled network elements.

    Science.gov (United States)

    2010-10-01

    ... elements. 51.311 Section 51.311 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON... § 51.311 Nondiscriminatory access to unbundled network elements. (a) The quality of an unbundled network element, as well as the quality of the access to the unbundled network element, that an incumbent...

  1. ANALISIS TRANSFER RATE PENAMBAHAN NODE PADA INFRASTRUKTUR MOBILE ADHOC NETWORK (MANET UNTUK FILE SERVER

    Directory of Open Access Journals (Sweden)

    Rudi Kurniawan

    2017-05-01

    Full Text Available Teknologi Wireless Network sudah lama ditemukan dan seiring waktu juga mengalami perkembangan, Namun sifat teknologi ini menggantungkan diri pada infrastruktur jaringan yang ada. Hal ini bias menjadi kelemahan tersendiri saat kondisi infrastruktur jaringan sedang mengalami gangguan, karena setiap komunikasi yang melewati infrastruktur jaringan tersebut tidak akan sampai pada tujuan. Teknologi jaringan Mobile Ad-hoc Network (MANET diciptakan sebagai antisipasi jika infrastruktur jaringan sedang mengalami gangguan. Dengan jaringan MANET sistem komunikasi yang dilakukan tidak membutuhkan infrastruktur jaringan karena tiap node pada jaringan tersebut bersifat mobile. Untuk menguji kemampuan MANET, pada penelitian ini akan menerapkan File Transfer Protocol (FTP sebagai media untuk melakukan komunikasi data file transfer yang diimplementasi pada jaringan MANET. Dari pengujian yang telah dilakukan diperoleh hasil bahwa File Transfer dapat berfungsi dengan baik saat diterapkan pada jaringan MANET.

  2. Large File Transfers from Space Using Multiple Ground Terminals and Delay-Tolerant Networking

    Science.gov (United States)

    Ivancic, William D.; Paulsen, Phillip; Stewart, Dave; Eddy, Wesley; McKim, James; Taylor, John; Lynch, Scott; Heberle, Jay; Northam, James; Jackson, Chris; hide

    2010-01-01

    We use Delay-Tolerant Networking (DTN) to break control loops between space-ground communication links and ground-ground communication links to increase overall file delivery efficiency, as well as to enable large files to be proactively fragmented and received across multiple ground stations. DTN proactive fragmentation and reactive fragmentation were demonstrated from the UK-DMC satellite using two independent ground stations. The files were reassembled at a bundle agent, located at Glenn Research Center in Cleveland Ohio. The first space-based demonstration of this occurred on September 30 and October 1, 2009. This paper details those experiments. Communication, delay-tolerant networking, DTN, satellite, Internet, protocols, bundle, IP, TCP.

  3. 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.

  4. Steep optical filtering for next generation optical access networks

    Science.gov (United States)

    Korček, Dušan; Müllerová, Jarmila

    2012-01-01

    Future development of optical access technologies expects increasing traffic and bandwidth. The first candidates to improve Gigabit-capable passive optical networks (GPON) are 10-Gigabit-PON (XG-PON) and wavelength-division multiplexing PON (WDM PON). Another possibility for increasing penetration of current PON branch is to extend number of channels provided on one optical fiber for one PON technology. Coexistence of GPON, XG-PON and WDM-PON in the same infrastructure is a most discussed issue concerning passive optical networks nowadays. Therefore, extensive studies are necessary to design proper and low-cost candidates. International Telecommunication Union (ITU) allocates specific wavelength bands for the present status quo and the future development of access technologies. However, within coexistence, it is necessary to protect signals from various PON technologies from interference. A potential barrier to deploying XG-GPONs and WDM PONs with current GPONs is the usage of broadband light sources and sophisticated optical methods of slicing the light source emission into specific wavelength channels. Protective measures comprise the exact allocation of upstream and downstream signal bands for each technology; the so-called guard bands within the wavelength allocation scheme to protect signals; and optionally the usage of wavelength blocking filters. In this contribution, bandpass thin-film filters are numerically presented for hybrid time division/wavelength division multiplexing TDM/WDM (TWDM) and for simple operation. They have been designed to be tunable and as steep as possible to reject the wavelength bands outside those allocated to TWDM-PON. The TWDM-PON filters are proposed to guarantee steep transmission curves in the vicinity of cut-on/cut-off wavelengths of the specific allocated wavelength bands and facilitate migration from legacy GPON and XG-PON to TWDM-PON. Their deployment protects the allocated wavelength bands from the undesirable interference.

  5. [Dentistry and healthcare legislation 10. The law governing complaints: readily accessible filing procedures].

    Science.gov (United States)

    van der Ven, J M; Eijkman, M A J; Brands, W G

    2014-03-01

    The law promises patients a readily accessible means of filing complaints. Healthcare providers are therefore required to adopt regulations governing complaints which satisfy a number of conditions. Most dentists choose to adopt the regulations which have been established by their professional organization. In addition to handling complaints, there is also a provision for mediation, which is often used by patients. Mediation appears, then, to be a successful provision. Many complaints have their origin in insufficient knowledge of healthcare legislation and patients' rights legislation. This demonstrates that more attention should be given to these subjects in educational programmes and programmes in continuing education. The present law governing complaints is expected to be replaced this year by a new, more comprehensive law in which considerable attention will be devoted to the quality of care as well as to complaints. It seems likely, however, that the new law governing complaints will damage the effective manner in which patients' complaints are dealt with in dentistry today.

  6. Scaling laws for file dissemination in P2P networks with random contacts

    NARCIS (Netherlands)

    Núñez-Queija, R.; Prabhu, B.

    2008-01-01

    In this paper we obtain the scaling law for the mean broadcast time of a file in a P2P network with an initial population of N nodes. In the model, at Poisson rate lambda a node initiates a contact with another node chosen uniformly at random. This contact is said to be successful if the contacted

  7. Fountain-code Aided File Transfer in Vehicular Delay Tolerant Networks

    Directory of Open Access Journals (Sweden)

    YOUSEFI, S.

    2013-11-01

    Full Text Available We propose a mechanism for facilitating file transferring in Vehicular Delay Tolerant Networks. The proposed architecture includes using Fountain coding in the application layer, UDP in the transport layer and a proposed DTN routing algorithm in the network layer. It is assumed that files are coded based on a sample of Fountain codes which does not need in-order reception of packets. As a result, there is no need of using close-loop reliable protocols such as TCP, hence suffering from their different overheads; as a result, UDP can be used in the transport layer. In the network layer, we propose a novel DTN routing algorithm based on AODV and Store-Carry and Forward policy. This algorithm (named as AODV-DTN uses a cross layer interaction between the network and the application layer. Results of extensive simulations study for highway scenarios show that the proposed architecture leads to a better performance in terms of file delivery ratio and byte throughput when compared with FOUNTAIN and classic FTP scenarios. Furthermore, the negative effect of increasing file size is mitigated in comparison to other alternatives. It is also shown that for delay tolerant and long-distanced inter-RSU communications the proposed architecture behaves sufficiently well.

  8. Support networks and people with physical disabilities: social inclusion and access to health services

    National Research Council Canada - National Science Library

    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...

  9. 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...... and computes power consumption and mismatch probability [1] in each of these access strategies. Based on our study, we make some recommendations when and where, which access strategy is suitable depending upon the application's requirements and network behavior. It also provides the model implementation...

  10. 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....

  11. DataMover: robust terabyte-scale multi-file replication overwide-area networks

    Energy Technology Data Exchange (ETDEWEB)

    Sim, Alex; Gu, Junmin; Shoshani, Arie; Natarajan, Vijaya

    2004-04-05

    Typically, large scientific datasets (order of terabytes) are generated at large computational centers, and stored on mass storage systems. However, large subsets of the data need to be moved to facilities available to application scientists for analysis. File replication of thousands of files is a tedious, error prone, but extremely important task in scientific applications. The automation of the file replication task requires automatic space acquisition and reuse, and monitoring the progress of staging thousands of files from the source mass storage system, transferring them over the network, archiving them at the target mass storage system or disk systems, and recovering from transient system failures. We have developed a robust replication system, called DataMover, which is now in regular use in High-Energy-Physics and Climate modeling experiments. Only a single command is necessary to request multi-file replication or the replication of an entire directory. A web-based tool was developed to dynamically monitor the progress of the multi-file replication process.

  12. A Web Service for File-Level Access to Disk Images

    Directory of Open Access Journals (Sweden)

    Sunitha Misra

    2014-07-01

    Full Text Available Digital forensics tools have many potential applications in the curation of digital materials in libraries, archives and museums (LAMs. Open source digital forensics tools can help LAM professionals to extract digital contents from born-digital media and make more informed preservation decisions. Many of these tools have ways to display the metadata of the digital media, but few provide file-level access without having to mount the device or use complex command-line utilities. This paper describes a project to develop software that supports access to the contents of digital media without having to mount or download the entire image. The work examines two approaches in creating this tool: First, a graphical user interface running on a local machine. Second, a web-based application running in web browser. The project incorporates existing open source forensics tools and libraries including The Sleuth Kit and libewf along with the Flask web application framework and custom Python scripts to generate web pages supporting disk image browsing.

  13. A Hub Location Problem with Fully Interconnected Backbone and Access Networks

    DEFF Research Database (Denmark)

    Thomadsen, Tommy; Larsen, Jesper

    2007-01-01

    This paper considers the design of two-layered fully interconnected networks. A two-layered network consists of clusters of nodes, each defining an access network and a backbone network. We consider the integrated problem of determining the access networks and the backbone network simultaneously...... problems. We obtain superior bounds using the column generation approach than with the linear programming relaxation. The column generation method is therefore developed into an exact approach using the Branch-and-Price framework. With this approach we are able to solve problems consisting of up to 25...

  14. GPON: the next big thing in optical access networks

    Science.gov (United States)

    Marmur, Oren; Shraga, Eyal

    2004-04-01

    This paper contains a comprehensive review of the various Passive Optical Network (PON) technologies in the marketplace today, namely APON, EPON and GPON, and draws an in-depth comparison between them. Following a review of the history of the various PON flavors, as well as the service requirements set forth by service providers, the emerging Gigabit PON (GPON) technology is examined in detail. System performance between the various protocols is compared using efficiency and scalability factors, and conclusions are drawn as to the overall throughput efficiency of and cost influence on the solution. GPON carries a two-fold promise of both higher bit rates and higher efficiency when carrying multiple services over the PON. It offers a scalable framing structure from 622Mb/s to 2.5Gb/s, as well as support for asymmetric bit rates, exceptionally high bandwidth utilization for any type of service and a variant of standard ITU-T Generic Framing Protocol (GFP) encapsulation of any type of service (both TDM and packet) onto a synchronous transport protocol. It is shown that in the worst-case scenario, based upon the most conservative assumptions regarding traffic distribution, GPON is substantially more efficient, with an overall efficiency of 93% compared to 71% with APON and 49% with EPON. Using a more detailed analysis based upon a traffic model provided by the service providers within the full service access networks (FSAN) consortium, it is shown in quantitative terms that GPON offers exceptionally higher bandwidth for the entire range of applications when compared to both APON and, especially, EPON, resulting in substantially lower cost per bit and a much faster payback period.

  15. 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)

  16. Coral and artificial reef shape files, Broward County, Florida, (NODC Accession 0000244)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Coral reef and artificial reef location shape files and accompanying table files for reefs located off shore of Broward County, Florida. Accompanying "attribute"...

  17. Supplement B: Research Networking Systems Characteristics Profiles. A Companion to the OCLC Research Report, Registering Researchers in Authority Files

    Science.gov (United States)

    Smith-Yoshimura, Karen; Altman, Micah; Conlon, Michael; Cristán, Ana Lupe; Dawson, Laura; Dunham, Joanne; Hickey, Thom; Hill, Amanda; Hook, Daniel; Horstmann, Wolfram; MacEwan, Andrew; Schreur, Philip; Smart, Laura; Wacker, Melanie; Woutersen, Saskia

    2014-01-01

    The OCLC Research Report, "Registering Researchers in Authority Files", [Accessible in ERIC as ED564924] summarizes the results of the research conducted by the OCLC Research Registering Researchers in Authority Files Task Group in 2012-2014. Details of this research are in supplementary data sets: (1) "Supplement A: Use Cases. A…

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

    DEFF Research Database (Denmark)

    Papaefthimiou, Kostantinos; Tefera, Yonas; Mihylov, Dimitar

    2013-01-01

    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...

  19. Peer Relations and Access to Capital in the Mathematics Classroom: A Bourdieusian Social Network Analysis

    Science.gov (United States)

    Choudry, Sophina; Williams, Julian; Black, Laura

    2017-01-01

    The aim of this article is to explore the structure of social capital in peer networks and its relation to the unequal access of educational resources within mathematics classrooms. We hypothesise that learners can gain access to mathematics through friendship networks which provide more or less help from peers that might sustain (or curtail)…

  20. F2AC: A Lightweight, Fine-Grained, and Flexible Access Control Scheme for File Storage in Mobile Cloud Computing

    Directory of Open Access Journals (Sweden)

    Wei Ren

    2016-01-01

    Full Text Available Current file storage service models for cloud servers assume that users either belong to single layer with different privileges or cannot authorize privileges iteratively. Thus, the access control is not fine-grained and flexible. Besides, most access control methods at cloud servers mainly rely on computationally intensive cryptographic algorithms and, especially, may not be able to support highly dynamic ad hoc groups with addition and removal of group members. In this paper, we propose a scheme called F2AC, which is a lightweight, fine-grained, and flexible access control scheme for file storage in mobile cloud computing. F2AC can not only achieve iterative authorization, authentication with tailored policies, and access control for dynamically changing accessing groups, but also provide access privilege transition and revocation. A new access control model called directed tree with linked leaf model is proposed for further implementations in data structures and algorithms. The extensive analysis is given for justifying the soundness and completeness of F2AC.

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

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

    This phase will endeavor to expand the existing network to include two thematic networks on food security and rural enterprise, respectively. A third thematic network - on knowledge management strategies - will play an advisory and support role to the larger network. Project activities will include a call for research proposals ...

  2. Media access control and resource allocation for next generation passive optical networks

    CERN Document Server

    Ansari, Nirwan

    2013-01-01

    This book focuses on various Passive optical networks (PONs)  types, including currently deployed Ethernet PON (EPON) and Gigabit PON (GPON) as well as next generation WDM PON and OFDM PON. Also this book examines the integrated optical and wireless access networks. Concentrating on two issues in these networks: media access control (MAC) and resource allocation. These two problems can greatly affect performances of PONs such as network resource utilization and QoS of end users. Finally this book will discuss various solutions to address the MAC and resource allocation issues in various PON networks.

  3. 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...

  4. Experimental realization of an entanglement access network and secure multi-party computation

    Science.gov (United States)

    Chang, Xiuying; Deng, Donglin; Yuan, Xinxing; Hou, Panyu; Huang, Yuanyuan; Duan, Luming; Department of Physics, University of Michigan Collaboration; Center for Quantum Information in Tsinghua University Team

    2017-04-01

    To construct a quantum network with many end users, it is critical to have a cost-efficient way to distribute entanglement over different network ends. We demonstrate an entanglement access network, where the expensive resource, the entangled photon source at the telecom wavelength and the core communication channel, is shared by many end users. Using this cost-efficient entanglement access network, we report experimental demonstration of a secure multiparty computation protocol, the privacy-preserving secure sum problem, based on the network quantum cryptography.

  5. Implementasi Network Attached Storage (NAS Menggunakan NAS4Free untuk Media Backup File

    Directory of Open Access Journals (Sweden)

    Kartika Imam Santoso

    2016-02-01

    Full Text Available STMIK Bina Patria Magelang adalah sekolah tinggi yang berada di jalan Raden Saleh No.2 Magelang, yang membidangi dalam ilmu komputer. STMIK Bina Patria mempunyai file–file pekerjaan yang sangat penting dan privasi, sehingga perlu untuk adanya sistem yang berguna untuk backup file. Network Attached Storage (NAS adalah sebuah server dengan sistem operasi yang dikhususkan untuk melayani kebutuhan berkas data. NAS dapat berbentuk perangkat yang siap pakai atau berupa sebuah software yang akan di-install-kan pada sebuah komputer agar berubah fungsi menjadi server NAS. Untuk software ini menggunakan NAS4Free yang berbasis linux. Model pengembangan sistem menggunakan Network Development Life Cycle (NDLC, adapun siklus tahapannya berisi analysis, design, simulation, prototyping, implementation, monitoring sehingga perencanaan yang akan dilakukan diharapkan bisa maksimal. Berdasarkan hasil pengujian terhadap rata-rata upload-nya adalah 3,5 Mbps, sedangkan untuk rata-rata download-nya adalah 5,63Mbps. 

  6. The Role of Social Network Locations in the College Access Mentoring of Urban Youth

    Science.gov (United States)

    Ahn, June

    2010-01-01

    This study uses social network analysis to describe the social network of college mentors in a college access program. Urban students in the program are paired with college mentors-students, professors, and other institutional agents-to help improve their college going process. The study analyzes the social networks within which the mentors are…

  7. Integrated self-management for future radio access networks: Vision and key challenges

    NARCIS (Netherlands)

    Eisenblätter, A.; Conzalez Rodríguez, B.; Gunnarsson, F.; Kürner, T.; Litjens, R.; Sas, B.; Sayrac, B.; Schmelz, L.C.; Willcock, C.

    2013-01-01

    Future radio access networks will require new self-management solutions to handle the increasing operational complexity caused by multi-technology and multi-layer deployments. Current networks already include stand-alone SON (Self-Organizing Networks) solutions, but these are not sufficient to

  8. Provision of metro ethernet services using a reconfigurable photonic access network

    NARCIS (Netherlands)

    Roy, R.; van Etten, Wim

    2007-01-01

    The paper proposes a design for traffic engineering to provide Ethernet services using an extended access network. Ethernet has remained the dominant technology for Local Area and Enterprise Networks, the use of Ethernet in metro networks has seen significant interest of late to provide for end to

  9. Project Integration Architecture (PIA) and Computational Analysis Programming Interface (CAPRI) for Accessing Geometry Data from CAD Files

    Science.gov (United States)

    Benyo, Theresa L.

    2002-01-01

    Integration of a supersonic inlet simulation with a computer aided design (CAD) system is demonstrated. The integration is performed using the Project Integration Architecture (PIA). PIA provides a common environment for wrapping many types of applications. Accessing geometry data from CAD files is accomplished by incorporating appropriate function calls from the Computational Analysis Programming Interface (CAPRI). CAPRI is a CAD vendor neutral programming interface that aids in acquiring geometry data directly from CAD files. The benefits of wrapping a supersonic inlet simulation into PIA using CAPRI are; direct access of geometry data, accurate capture of geometry data, automatic conversion of data units, CAD vendor neutral operation, and on-line interactive history capture. This paper describes the PIA and the CAPRI wrapper and details the supersonic inlet simulation demonstration.

  10. Research the dynamical large file transmitting in optical network using Lagrangian relaxation

    Science.gov (United States)

    Wang, Hao; Guo, Wei; Jin, Yaohui; Sun, Weiqiang; Hu, Weisheng

    2008-11-01

    In today's distributed computing systems, a large amount files contain huge data need to be transferred to their destination as soon as possible or else the quality of these systems will be seriously affected, and these transfer requests arrived dynamically. We propose some effective heuristic algorithm to this problem with the purposes of minimizing the maximal file transmitting time, and we can get some primal results from the algorithm. However, as we known, the problem of routing and scheduling for the dynamic arriving files in the optical network has a large number of constrains and the exact solution is computationally expensive, so it is hard to get the optimal result about this problem and we can not know whether the heuristic results is good or how closed it closed to its optimal result. In order to get some more detail results, we apply the approach called Lagrangian relaxation combined with subgradient-based method and utility the heuristic result to compute the lower bound of the optimal solution, and we consider the optimal target of minimizing the maximal file transmitting complete time for it's an important aspect with the file transmitting problem. We mainly use Lagrangian relaxation (LR) to research the dynamical lager file transmitting problem. Firstly, in order to apply the LR method we formulation our dynamic file routing scheduling and distributing problem in WDM optical network into mathematic model with some corresponding constraints. Secondly, change the formulation with some added variables to let it more suitable for LR and then introduce the Lagrangian multipliers into the model to obtain the Lagrangian function. With this function we can divided it into some small independent problems that could let it be solved more easily and at last we utilize the result received from the heuristic algorithm to solve the Lagrangian multiplier problem with subgradient-based method in order to getting the sharpest possible lower bound. With the

  11. 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

  12. A Measurement Study of the Structured Overlay Network in P2P File-Sharing Systems

    Directory of Open Access Journals (Sweden)

    Mo Zhou

    2007-08-01

    Full Text Available The architecture of P2P file-sharing applications has been developing to meet the needs of large scale demands. The structured overlay network, also known as DHT, has been used in these applications to improve the scalability, and robustness of the system, and to make it free from single-point failure. We believe that the measurement study of the overlay network used in the real file-sharing P2P systems can provide guidance for the designing of such systems, and improve the performance of the system. In this paper, we perform the measurement in two different aspects. First, a modified client is designed to provide view to the overlay network from a single-user vision. Second, the instances of crawler programs deployed in many nodes managed to crawl the user information of the overlay network as much as possible. We also find a vulnerability in the overlay network, combined with the character of the DNS service, a more serious DDoS attack can be launched.

  13. Multi-Resolution Playback of Network Trace Files

    Science.gov (United States)

    2015-06-01

    a com- plete MySQL database, C++ developer tools and the libraries utilized in the development of the system (Boost and Libcrafter), and Wireshark...XE suite has a limit to the allowed size of each database. In order to be scalable, the project had to switch to the MySQL database suite. The...programs that access the database use the MySQL C++ connector, provided by Oracle, and the supplied methods and libraries. 4.4 Flow Generator Chapter 3

  14. Logical optical line terminal technologies towards flexible and highly reliable metro- and access-integrated networks

    Science.gov (United States)

    Okamoto, Satoru; Sato, Takehiro; Yamanaka, Naoaki

    2017-01-01

    In this paper, flexible and highly reliable metro and access integrated networks with network virtualization and software defined networking technologies will be presented. Logical optical line terminal (L-OLT) technologies and active optical distribution networks (ODNs) are the key to introduce flexibility and high reliability into the metro and access integrated networks. In the Elastic Lambda Aggregation Network (EλAN) project which was started in 2012, a concept of the programmable optical line terminal (P-OLT) has been proposed. A role of the P-OLT is providing multiple network services that have different protocols and quality of service requirements by single OLT box. Accommodated services will be Internet access, mobile front-haul/back-haul, data-center access, and leased line. L-OLTs are configured within the P-OLT box to support the functions required for each network service. Multiple P-OLTs and programmable optical network units (P-ONUs) are connected by the active ODN. Optical access paths which have flexible capacity are set on the ODN to provide network services from L-OLT to logical ONUs (L-ONUs). The L-OLT to L-ONU path on the active ODN provides a logical connection. Therefore, introducing virtualization technologies becomes possible. One example is moving an L-OLT from one P-OLT to another P-OLT like a virtual machine. This movement is called L-OLT migration. The L-OLT migration provides flexible and reliable network functions such as energy saving by aggregating L-OLTs to a limited number of P-OLTs, and network wide optical access path restoration. Other L-OLT virtualization technologies and experimental results will be also discussed in the paper.

  15. 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.

  16. A cost model for broadband access networks: FTTx versus WiMAX

    Science.gov (United States)

    Pereira, João Paulo Ribeiro

    2007-09-01

    Local communities and governments are taking various steps to fight the so-called "digital divide" between well served urban communities and undeserved areas. In order to make broadband access available to these under served areas, several technical solutions are available with the capacity to provide high speed Internet access, video, telephony services, etc. This paper presents a cost-model and a tool for the evaluation of broadband access technologies (xDSL, HFC, FTTx, WiMAX, PLC and satellite), and compares two technologies: FTTx and WiMAX. Our tool compares these different access technologies in different scenarios, and examining the capital expense and deployment of building access networks with the same requisite performance using each technology. The cost model is limited to the access part of the network. The results obtained by our evaluation tool give the possibility to compare several BB access technologies, and support the decision about which is the better technological solution for a given scenario

  17. Transport network extensions for accessibility analysis in geographic information systems

    NARCIS (Netherlands)

    Jong, Tom de; Tillema, T.

    2005-01-01

    In many developed countries high quality digital transport networks are available for GIS based analysis. Partly this is due to the requirements of route planning software for internet and car navigation systems. Properties of these networks consist among others of road quality attributes,

  18. Resource Sharing in Heterogeneous and Cloud Radio Access Networks

    DEFF Research Database (Denmark)

    Zakrzewska, Anna; Iversen, Villy Bæk

    2012-01-01

    This paper analyzes performance of cellular systems with shared resources, where the network with overlapping cells is modeled as a circuit switched network with direct routing. The influence of the degree of sharing, represented by cell overlap percentage, on the call blocking probability is inv...

  19. 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....

  20. ABCDecision: A Simulation Platform for Access Selection Algorithms in Heterogeneous Wireless Networks

    Directory of Open Access Journals (Sweden)

    Guy Pujolle

    2010-01-01

    Full Text Available We present a simulation platform for access selection algorithms in heterogeneous wireless networks, called “ABCDecision”. The simulator implements the different parts of an Always Best Connected (ABC system, including Access Technology Selector (ATS, Radio Access Networks (RANs, and users. After describing the architecture of the simulator, we show an overview of the existing decision algorithms for access selection. Then we propose a new selection algorithm in heterogeneous networks and we run a set of simulations to evaluate the performance of the proposed algorithm in comparison with the existing ones. The performance results, in terms of the occupancy rate, show that our algorithm achieves a load balancing distribution between networks by taking into consideration the capacities of the available cells.

  1. Android Access Control Extension

    Directory of Open Access Journals (Sweden)

    Anton Baláž

    2015-12-01

    Full Text Available The main objective of this work is to analyze and extend security model of mobile devices running on Android OS. Provided security extension is a Linux kernel security module that allows the system administrator to restrict program's capabilities with per-program profiles. Profiles can allow capabilities like network access, raw socket access, and the permission to read, write, or execute files on matching paths. Module supplements the traditional Android capability access control model by providing mandatory access control (MAC based on path. This extension increases security of access to system objects in a device and allows creating security sandboxes per application.

  2. Medium Access Control for Wireless Sensor Networks based on Impulse Radio Ultra Wideband

    OpenAIRE

    Berthe, Abdoulaye; Lecointre, Aubin; Dragomirescu, Daniela; Plana, Robert

    2010-01-01

    This paper describes a detailed performance evaluation of distributed Medium Access Control (MAC) protocols for Wireless Sensor Networks based on Impulse Radio Ultra Wideband (IR-UWB) Physical layer (PHY). Two main classes of Medium Access Control protocol have been considered: Slotted and UnSlotted with reliability. The reliability is based on Automatic Repeat ReQuest (ARQ). The performance evaluation is performed using a complete Wireless Sensor Networks (WSN) simulator built on the Global ...

  3. System Architecture and Key Technologies for 5G Heterogeneous Cloud Radio Access Networks

    OpenAIRE

    Peng, Mugen; Li, Yong; Zhao, Zhongyuan; Wang, Chonggang

    2014-01-01

    Compared with the fourth generation (4G) cellular systems, the fifth generation wireless communication systems (5G) are anticipated to provide spectral and energy efficiency growth by a factor of at least 10, and the area throughput growth by a factor of at least 25. To achieve these goals, a heterogeneous cloud radio access network (H-CRAN) is presented in this article as the advanced wireless access network paradigm, where cloud computing is used to fulfill the centralized large-scale coope...

  4. Enabling multimode wireless access networks using remote radio heads

    DEFF Research Database (Denmark)

    Kardaras, Georgios; Soler, José; Dittmann, Lars

    2012-01-01

    The deployment of 4G networks is spreading rapidly providing mobile broadband services to the public. 4G technologies are designed to overlay existing 3G networks enabling reusability of several network components. In this way, the coexistence of 3G/4G standards is facilitated. This paper describes...... and management plane. Switching between wireless standards becomes easily feasible through firmware upgrading. Finally, real-time configuration of radio functionalities, such as transmit power, receiver gain, carrier frequency, channel bandwidth and others result in a modular software defined radio platform....... © 2012 ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering....

  5. Secure Access Management for a Secret Operational Network (SAMSON) Technology Demonstrator (TD). Empire Challenge (EC) / Coalition Warrior Interoperability Demonstration (CWID)

    Science.gov (United States)

    2011-08-15

    Services hosted on this network include connectivity service such as VPN servers and common services used across all networks such as LDAP and DNS...of one database, one LDAP Directory, and a high number of configuration files requiring modifications can take up to 3 days with a full set of...production grade documentation. The Samson system has two databases, one ldap directory, eleven server machines, and many configuration files which need

  6. 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 ...

  7. An Ounce of Prevention: Technologists Use Network-Access Control to Protect System Resources, Students

    Science.gov (United States)

    Bolch, Matt

    2009-01-01

    Whether for an entire district, a single campus, or one classroom, allowing authorized access to a computer network can be fraught with challenges. The login process should be fairly seamless to approved users, giving them speedy access to approved Web sites, databases, and other sources of information. It also should be tough on unauthorized…

  8. The Cybermobile: A Gateway for Public Access to Network-Based Information.

    Science.gov (United States)

    Drumm, John E.; Groom, Frank M.

    1997-01-01

    Though the bookmobile has fallen on hard times, the cybermobile, a technology platform combining personal computing, CD-ROMs, fiber network, and wireless access to the Internet, may be the next step in mobile library services. Discusses standard vehicle, computer hardware, software, wireless access, and alliances with users, vendors, and community…

  9. An Efficient Medium Access Control Strategy for High Speed WDM Multiaccess Networks

    NARCIS (Netherlands)

    Laarhuis, Jan H.; Laarhuis, Jan; Koonen, A.M.J.

    1993-01-01

    A medium access control (MAC) strategy that accounts for the limited tunability of present-day lasers and filters and yet supports a large total number of wavelengths in the network is proposed. Full interconnectivity, contention-free access and a high value of concurrency are achieved by dividing

  10. Transport capacity of wireless networks: benefits from multi-access computation coding

    NARCIS (Netherlands)

    Goseling, Jasper; Gastpar, Michael; Weber, Jos H.

    2009-01-01

    We consider the effect on the transport capacity of wireless networks of different physical layer coding mechanisms. We compare the performance of traditional channel coding techniques, turning the wireless network in reliable point-to-point channels, with multi-access computation coding, in which

  11. The Changing Role of Community Networks in Providing Citizen Access to the Internet.

    Science.gov (United States)

    Keenan, Thomas P.; Trotter, David Mitchell

    1999-01-01

    Examines the changing role of community network associations or freenets in providing Internet access by examining the case of the Calgary Community Network Association (CCNA) in Alberta, Canada. Discusses the withdrawal of states from the telecommunications field, priorities of the Canadian government, and the role of the private sector.…

  12. 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

  13. Hybrid InP-SiGe photoreceiver for the access network

    NARCIS (Netherlands)

    Urban, P.J.; Leijtens, X.J.M.; Smalbrugge, E.; Vries, T. de; Noetzel, R.; Oei, Y.S.; Xu, L.; Heijningen, M. van; Bent, G. van der; Waardt, H. de; Smit, M.K.

    2008-01-01

    In this paper, we present a low cost and polarization independent photoreceiver which is part of the optical network unit (ONU) for the fiber access network. It consists of one InPphotodetector and a low cost SiGe amplifier. It operates error free with 223 − 1 PRBS word length at 1.25 Gbit/s with

  14. 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...

  15. MetNetAPI: A flexible method to access and manipulate biological network data from MetNet.

    Science.gov (United States)

    Sucaet, Yves; Wurtele, Eve Syrkin

    2010-11-18

    Convenient programmatic access to different biological databases allows automated integration of scientific knowledge. Many databases support a function to download files or data snapshots, or a webservice that offers "live" data. However, the functionality that a database offers cannot be represented in a static data download file, and webservices may consume considerable computational resources from the host server. MetNetAPI is a versatile Application Programming Interface (API) to the MetNetDB database. It abstracts, captures and retains operations away from a biological network repository and website. A range of database functions, previously only available online, can be immediately (and independently from the website) applied to a dataset of interest. Data is available in four layers: molecular entities, localized entities (linked to a specific organelle), interactions, and pathways. Navigation between these layers is intuitive (e.g. one can request the molecular entities in a pathway, as well as request in what pathways a specific entity participates). Data retrieval can be customized: Network objects allow the construction of new and integration of existing pathways and interactions, which can be uploaded back to our server. In contrast to webservices, the computational demand on the host server is limited to processing data-related queries only. An API provides several advantages to a systems biology software platform. MetNetAPI illustrates an interface with a central repository of data that represents the complex interrelationships of a metabolic and regulatory network. As an alternative to data-dumps and webservices, it allows access to a current and "live" database and exposes analytical functions to application developers. Yet it only requires limited resources on the server-side (thin server/fat client setup). The API is available for Java, Microsoft.NET and R programming environments and offers flexible query and broad data- retrieval methods. Data

  16. MetNetAPI: A flexible method to access and manipulate biological network data from MetNet

    Directory of Open Access Journals (Sweden)

    Sucaet Yves

    2010-11-01

    Full Text Available Abstract Background Convenient programmatic access to different biological databases allows automated integration of scientific knowledge. Many databases support a function to download files or data snapshots, or a webservice that offers "live" data. However, the functionality that a database offers cannot be represented in a static data download file, and webservices may consume considerable computational resources from the host server. Results MetNetAPI is a versatile Application Programming Interface (API to the MetNetDB database. It abstracts, captures and retains operations away from a biological network repository and website. A range of database functions, previously only available online, can be immediately (and independently from the website applied to a dataset of interest. Data is available in four layers: molecular entities, localized entities (linked to a specific organelle, interactions, and pathways. Navigation between these layers is intuitive (e.g. one can request the molecular entities in a pathway, as well as request in what pathways a specific entity participates. Data retrieval can be customized: Network objects allow the construction of new and integration of existing pathways and interactions, which can be uploaded back to our server. In contrast to webservices, the computational demand on the host server is limited to processing data-related queries only. Conclusions An API provides several advantages to a systems biology software platform. MetNetAPI illustrates an interface with a central repository of data that represents the complex interrelationships of a metabolic and regulatory network. As an alternative to data-dumps and webservices, it allows access to a current and "live" database and exposes analytical functions to application developers. Yet it only requires limited resources on the server-side (thin server/fat client setup. The API is available for Java, Microsoft.NET and R programming environments and offers

  17. Making the Most out of Direct-Access Network Attached Storage

    OpenAIRE

    Fedorova, Alexandra; Magoutis, Kostas; Addetia, Salimah; Seltzer, Margo

    2003-01-01

    The performance of high-speed network-attached storage applications is often limited by end-system overhead, caused primarily by memory copying and network protocol processing. In this paper, we examine alternative strategies for reducing overhead in such systems. We consider optimizations to remote procedure call (RPC)-based data transfer using either remote direct memory access (RDMA) or network interface support for pre-posting of application receive buffers. We demonstrate that b...

  18. 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...

  19. Reconfigurable radio access unit to dynamically distribute W-band signals in 5G wireless access networks

    DEFF Research Database (Denmark)

    Rodríguez Páez, Juan Sebastián; Rommel, Simon; Vegas Olmos, Juan José

    2017-01-01

    In this paper a new type of radio access unit is proposed and demonstrated. This unit is composed only of the reduced amount of components (compared to conventional unit designs) to optically generate wireless signals on the W-band (75–110 GHz) in combination with a switching system. The proposed...... system not only achieves BER values below the FEC limit, but gives an extra level of flexibility to the network by easing the redirection of the signal to different antennas....

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

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

    Africa is a net importer of intellectual property covered by copyright rules. The African Comparative Copyright Review (ACCR) believes that a stringent copyright climate could limit access to knowledge goods and thereby hinder the emergence of local innovation and learning. This project will allow the ACCR to bring ...

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

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

    Legislative review : review of IPR Act and regulations : Intellectual Property Rights from Publically Financed Research and Development Act, Act No. 51 of 2008, Republic of South Africa. Download PDF. Journal articles. Copyright and education : lessons on African copyright and access to knowledge. Download PDF ...

  2. PIMS Data Storage, Access, and Neural Network Processing

    Science.gov (United States)

    McPherson, Kevin M.; Moskowitz, Milton E.

    1998-01-01

    The Principal Investigator Microgravity Services (PIMS) project at NASA's Lewis Research Center has supported microgravity science Principal Investigator's (PIs) by processing, analyzing, and storing the acceleration environment data recorded on the NASA Space Shuttles and the Russian Mir space station. The acceleration data recorded in support of the microgravity science investigated on these platforms has been generated in discrete blocks totaling approximately 48 gigabytes for the Orbiter missions and 50 gigabytes for the Mir increments. Based on the anticipated volume of acceleration data resulting from continuous or nearly continuous operations, the International Space Station (ISS) presents a unique set of challenges regarding the storage of and access to microgravity acceleration environment data. This paper presents potential microgravity environment data storage, access, and analysis concepts for the ISS era.

  3. Opportunistic Access in Frequency Hopping Cognitive Radio Networks

    Science.gov (United States)

    2014-03-27

    frequency hopping radio to mitigate the interference caused by other transmitters in a contentious environment such as the unlicensed 2.4 GHz region...Avionics Circle WPAFB, OH 45433 vasu.chakravarthy@us.af.mil 937- 528 -8269 AFRL/RYWE 12. DISTRIBUTION / AVAILABILITY STATEMENT DISTRIBUTION STATEMENT A...unlicensed 2.4 GHz region. Additionally, this work demonstrates how dynamic spectrum access techniques can be used not only to prevent interfering with

  4. 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.

  5. Trust in social computing. The case of peer-to-peer file sharing networks

    Directory of Open Access Journals (Sweden)

    Heng Xu

    2011-09-01

    Full Text Available Social computing and online communities are changing the fundamental way people share information and communicate with each other. Social computing focuses on how users may have more autonomy to express their ideas and participate in social exchanges in various ways, one of which may be peer-to-peer (P2P file sharing. Given the greater risk of opportunistic behavior by malicious or criminal communities in P2P networks, it is crucial to understand the factors that affect individual’s use of P2P file sharing software. In this paper, we develop and empirically test a research model that includes trust beliefs and perceived risks as two major antecedent beliefs to the usage intention. Six trust antecedents are assessed including knowledge-based trust, cognitive trust, and both organizational and peer-network factors of institutional trust. Our preliminary results show general support for the model and offer some important implications for software vendors in P2P sharing industry and regulatory bodies.

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

    Energy Technology Data Exchange (ETDEWEB)

    Soederholm, Patrik; Waarell, Linda [Luleaa University of Technology, Department of Business Administration and Social Sciences, Economics Unit, SE-971 87 Luleaa (Sweden)

    2011-02-15

    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. (author)

  7. 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.

  8. Analysis of physical layer performance of hybrid optical-wireless access network

    Science.gov (United States)

    Shaddad, R. Q.; Mohammad, A. B.; Al-hetar, A. M.

    2011-09-01

    The hybrid optical-wireless access network (HOWAN) is a favorable architecture for next generation access network. It is an optimal combination of an optical backhaul and a wireless front-end for an efficient access network. In this paper, the HOWAN architecture is designed based on a wavelengths division multiplexing/time division multiplexing passive optical network (WDM/TDM PON) at the optical backhaul and a wireless fidelity (WiFi) technology at the wireless front-end. The HOWAN is proposed that can provide blanket coverage of broadband and flexible connection for end-users. Most of the existing works, based on performance evaluation are concerned on network layer aspects. This paper reports physical layer performance in terms of the bit error rate (BER), eye diagram, and signal-to-noise ratio (SNR) of the communication system. It accommodates 8 wavelength channels with 32 optical network unit/wireless access points (ONU/APs). It is demonstrated that downstream and upstream of 2 Gb/s can be achieved by optical backhaul for each wavelength channel along optical fiber length of 20 km and a data rate of 54 Mb/s per ONU/AP along a 50 m outdoor wireless link.

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    set of requirements. Lastly, the paper suggests a mechanism by which the information access or acquisition can be adapted as per the requirements of the application. The main parameters focused in this paper are mismatch probability [1] and power dissipation with respect to sampling rate....... specific WSN considering its resource constraints, neglecting the return-of-investment and usefulness of the system. In this paper, we bring out the WSN scenario which supports multiple applications and study the challenges that would pose in implementation as each specific application has its own specific...

  10. Fairness problems at the media access level for high-speed networks

    Science.gov (United States)

    Maly, Kurt J.; Zhang, L.; Game, David

    1990-01-01

    Most lower speed (approx. 10 Mbps) local area networks use adaptive or random access protocols like Ethernet. Others at higher speed use demand assignment like token or slotted rings. These include Cambridge ring and electronic token ring systems. Fairness issues in representatives of such protocols are discussed. In particular, Fiber Distributed Data Interface (FDDI) was selected as a demand access protocol using tokens, Carrier Sensed Multiple Access/Ring Network (CSMA/RN) a random access protocol, and Distributed Queue Dual Bus (DQDB) a demand access protocol using reservations. Fairness at the media access level was the focus, i.e., attaining access or being excessively delayed when a message is queued to be sent as a function of network location. Within that framework, the essential fairness of FDDI was observed along with severe fairness problems in DQDB and some problems for CSMA/RN. Several modifications were investigated and their ameliorative effect is shown. Finally, a unified presentation which allows comparisons of the three protocols' fairness when normalized to their capacity is given.

  11. Setting Access Permission through Transitive Relationship in Web-based Social Networks

    Science.gov (United States)

    Hong, Dan; Shen, Vincent Y.

    The rising popularity of various social networking websites has created a huge problem on Internet privacy. Although it is easy to post photos, comments, opinions on some events, etc. on the Web, some of these data (such as a person’s location at a particular time, criticisms of a politician, etc.) are private and should not be accessed by unauthorized users. Although social networks facilitate sharing, the fear of sending sensitive data to a third party without knowledge or permission of the data owners discourages people from taking full advantage of some social networking applications. We exploit the existing relationships on social networks and build a ‘‘trust network’’ with transitive relationship to allow controlled data sharing so that the privacy and preferences of data owners are respected. The trust network linking private data owners, private data requesters, and intermediary users is a directed weighted graph. The permission value for each private data requester can be automatically assigned in this network based on the transitive relationship. Experiments were conducted to confirm the feasibility of constructing the trust network from existing social networks, and to assess the validity of permission value assignments in the query process. Since the data owners only need to define the access rights of their closest contacts once, this privacy scheme can make private data sharing easily manageable by social network participants.

  12. 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.

  13. 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...

  14. 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.

  15. 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 ...

  16. Impact of green technologies in optical networks case study: green wireless optical broadband access network

    Science.gov (United States)

    Puche, William S.; Sierra, Javier E.

    2014-09-01

    This article analyzes the current state of green technologies in optical telecommunications networks, analyzing in detail the basic structure of a hybrid network (Optical-Wireless), taking into account energy consumption by proposing a mathematical model is presented to establish the optimum number of ONUs in a network.

  17. 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

    time thresholds. The method is used successfully to create a multimodal travel-time network model of the Capital Region of Denmark comprising bus, train, light rail, metro, and ferry as well as integrating walking or cycling to stops. Here, the individual accessibility is defined as accessibility areas......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...... to integrate transit schedules into multimodal networks and measure space–time-based accessibility. This has caused authors to either simplify travel time elements or develop tools to overcome these challenges. In this paper we aim to describe and implement a method that enables integrating time-table data...

  18. A Framework Design for Load-balanced Green Access Networks supporting GSM Femtocell

    Directory of Open Access Journals (Sweden)

    Ray-Guang Cheng

    2015-02-01

    Full Text Available Reducing the energy consumption and carbon footprint emissions to improve the global climate change has become the global concern. However, CO2 generated from the current mobile devices and infrastructure has increased. Many researchers intended to develop the communication systems with low energy-consumption technologies, called the green communication. This paper proposes a framework of the load balanced green access network supporting the GSM femtocell service. By using the USRP software-defined radio device, we can build a GSM femtocell base station by software configuration. Besides, the proposed network can also extend the coverage of base stations by integrating with radio over fiber technology. With the load balancer, the proposed green access network can accomplish low power consumption, high energy efficiency, and easy to maintain. The experimental results showed that it can effectively save 24% energy consumption for the overall network and meet the quality-of-service of user when the proposed framework is applied.

  19. Performance Evaluation of 5G Millimeter-Wave Cellular Access Networks Using a Capacity-Based Network Deployment Tool

    Directory of Open Access Journals (Sweden)

    Michel Matalatala

    2017-01-01

    Full Text Available The next fifth generation (5G of wireless communication networks comes with a set of new features to satisfy the demand of data-intensive applications: millimeter-wave frequencies, massive antenna arrays, beamforming, dense cells, and so forth. In this paper, we investigate the use of beamforming techniques through various architectures and evaluate the performance of 5G wireless access networks, using a capacity-based network deployment tool. This tool is proposed and applied to a realistic area in Ghent, Belgium, to simulate realistic 5G networks that respond to the instantaneous bit rate required by the active users. The results show that, with beamforming, 5G networks require almost 15% more base stations and 4 times less power to provide more capacity to the users and the same coverage performances, in comparison with the 4G reference network. Moreover, they are 3 times more energy efficient than the 4G network and the hybrid beamforming architecture appears to be a suitable architecture for beamforming to be considered when designing a 5G cellular network.

  20. 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...

  1. MAC Protocols for Optimal Information Retrieval Pattern in Sensor Networks with Mobile Access

    Directory of Open Access Journals (Sweden)

    Dong Min

    2005-01-01

    Full Text Available In signal field reconstruction applications of sensor network, the locations where the measurements are retrieved from affect the reconstruction performance. In this paper, we consider the design of medium access control (MAC protocols in sensor networks with mobile access for the desirable information retrieval pattern to minimize the reconstruction distortion. Taking both performance and implementation complexity into consideration, besides the optimal centralized scheduler, we propose three decentralized MAC protocols, namely, decentralized scheduling through carrier sensing, Aloha scheduling, and adaptive Aloha scheduling. Design parameters for the proposed protocols are optimized. Finally, performance comparison among these protocols is provided via simulations.

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

    Science.gov (United States)

    Lin, Yun; Wang, Chao; Wang, Jiaxing; Dou, Zheng

    2016-10-12

    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.

  3. 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.

  4. Traffic Control Algorithm Offering Multi-Class Fairness in PON Based Access Networks

    Science.gov (United States)

    Okumura, Yasuyuki

    This letter proposes a dynamic bandwidth allocation algorithm for access networks based PON (Passive Optical Network). It considers the mixture of transport layer protocols when responding to traffic congestion at the SNI (Service Node Interface). Simulations on a mixture of TCP (Transmission Control Protocol), and UDP (User Datagram Protocol) traffic flows show that the algorithm increases the throughput of TCP, improves the fairness between the two protocols, and solves the congestion problem at the SNI.

  5. How to Cut the Electric Bill in Mobile Access Networks: A Mobile Operator's Perspective

    OpenAIRE

    Chatzimichail, Konstantinos

    2014-01-01

    One of the major challenges that mobile operators are facing is the increasing power consumption costs as a consequence of the network densication experienced in current and future mobile access networks. This power increase causes both financial and environmental concerns to operators, since both the operational expenses and the CO2 emissions are affected. This Master Thesis investigates and analyses various deployment architectures in urban and suburban areas, considering both the radio acc...

  6. Unsynchronized Energy-Efficient Medium Access Control and Routing in Wireless Sensor Networks

    Science.gov (United States)

    Hurni, Philipp

    This master thesis investigates optimizations on recently proposed fully unsynchronized power saving sensor MAC protocols. In contrast to many other sensor MAC protocols, unsynchronized sensor MAC protocols renounce on any kind of network- or cluster-wide synchronization for channel access coordination and maintenance of a common wake-sleep pattern, because in wireless sensor networks with low traffic requirements, the overhead for maintaining synchronization is likely to exceed the energy spent for the actual data traffic.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. Redirecting a client device from a first gateway to a second gateway for accessing a network node function

    NARCIS (Netherlands)

    Strijkers, R.J.; Norp, A.H.J.

    2014-01-01

    The present invention enables a network operator to select a gateway that provides desirable operational parameters to access a network node function in a network node requested by a client. A network service provider detects what service a client device is requesting or using and selects a gateway

  12. 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...... of contention, reservation and polling access techniques based on the dynamic TDMA system. Extensive simulation results using realistic data traffic sources, show that the proposed medium access scheme may provide QoS guarantees to different ATM traffic including the realistic MPEG video traces with low cell...

  13. Measuring geographic access to health care: raster and network-based methods

    Directory of Open Access Journals (Sweden)

    Delamater Paul L

    2012-05-01

    Full Text Available Abstract Background Inequalities in geographic access to health care result from the configuration of facilities, population distribution, and the transportation infrastructure. In recent accessibility studies, the traditional distance measure (Euclidean has been replaced with more plausible measures such as travel distance or time. Both network and raster-based methods are often utilized for estimating travel time in a Geographic Information System. Therefore, exploring the differences in the underlying data models and associated methods and their impact on geographic accessibility estimates is warranted. Methods We examine the assumptions present in population-based travel time models. Conceptual and practical differences between raster and network data models are reviewed, along with methodological implications for service area estimates. Our case study investigates Limited Access Areas defined by Michigan’s Certificate of Need (CON Program. Geographic accessibility is calculated by identifying the number of people residing more than 30 minutes from an acute care hospital. Both network and raster-based methods are implemented and their results are compared. We also examine sensitivity to changes in travel speed settings and population assignment. Results In both methods, the areas identified as having limited accessibility were similar in their location, configuration, and shape. However, the number of people identified as having limited accessibility varied substantially between methods. Over all permutations, the raster-based method identified more area and people with limited accessibility. The raster-based method was more sensitive to travel speed settings, while the network-based method was more sensitive to the specific population assignment method employed in Michigan. Conclusions Differences between the underlying data models help to explain the variation in results between raster and network-based methods. Considering that the

  14. Comparison of a Ring On-Chip Network and a Code-Division Multiple-Access On-Chip Network

    OpenAIRE

    Xin Wang; Jari Nurmi

    2007-01-01

    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, ...

  15. 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.

  16. Automation in accession classification of Brazilian Capsicum germplasm through artificial neural networks

    Directory of Open Access Journals (Sweden)

    Mariane Gonçalves Ferreira

    Full Text Available ABSTRACT Germplasm classification by species requires specific knowledge on/of the culture of interest. Therefore, efforts aimed at automation of this process are necessary for the efficient management of collections. Automation of germplasm classification through artificial neural networks may be a viable and less laborious strategy. The aims of this study were to verify the classification potential of Capsicum accessions regarding/ the species based on morphological descriptors and artificial neural networks, and to establish the most important descriptors and the best network architecture for this purpose. Five hundred and sixty-four plants from 47 Brazilian Capsicum accessions were evaluated. Neural networks of multilayer perceptron type were used in order to automate the species identification through 17 morphological descriptors. Six network architectures were evaluated, and the number of neurons in the hidden layer ranged from 1 to 6. The relative importance of morphological descriptors in the classification process was established by Garson's method. Corolla color, corolla spot color, calyx annular constriction, fruit shape at pedicel attachment, and fruit color at mature stage were the most important descriptors. The network architecture with 6 neurons in the hidden layer is the most appropriate in this study. The possibility of classifying Capsicum plants regarding/ the species through artificial neural networks with 100 % accuracy was verified.

  17. 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.

  18. A Low-Latency, Information-Centric Medium Access Protocol for Wireless Sensor Networks

    NARCIS (Netherlands)

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

    In this paper we present a novel TDMA-based medium access control (MAC) protocol for wireless sensor networks. Unlike conventional MAC protocols which function independently of the application, we introduce an Adaptive, Information-centric and Lightweight MAC(AI-LMAC) protocol that adapts its

  19. Request-TDMA: A multiple-access protocol for wireless multimedia networks

    NARCIS (Netherlands)

    Linnenbank, G.R.J.; Havinga, Paul J.M.; Smit, Gerardus Johannes Maria; Mullender, Sape J.; Smulders, P.; van den Meerendonk, H.

    1995-01-01

    This paper describes a cellular multiple-access scheme based on TDMA for multimedia communication networks. The scheme proposes an admission control of two different multimedia application stream types: real-time and non-real-time. We do not consider interference between cells. The proposed

  20. 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....

  1. 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.

  2. 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 c...

  3. 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

  4. 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...

  5. Use and benefits of public access defibrillation in a nation-wide network

    DEFF Research Database (Denmark)

    Nielsen, Anne Møller; Folke, Fredrik; Lippert, Freddy Knudsen

    2013-01-01

    BACKGROUND: Automated External Defibrillators (AEDs) are known to increase survival after out-of-hospital cardiac arrest (OHCA). The aim of this study was to examine the use and benefit of public-access defibrillation (PAD) in a nation-wide network. We primarily sought to assess survival at 1 month...

  6. 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...

  7. Optical network unit placement in Fiber-Wireless (FiWi) access network by Moth-Flame optimization algorithm

    Science.gov (United States)

    Singh, Puja; Prakash, Shashi

    2017-07-01

    Hybrid wireless-optical broadband access network (WOBAN) or Fiber-Wireless (FiWi) is the integration of wireless access network and optical network. This hybrid multi-domain network adopts the advantages of wireless and optical domains and serves the demand of technology savvy users. FiWi exhibits the properties of cost effectiveness, robustness, flexibility, high capacity, reliability and is self organized. Optical Network Unit (ONU) placement problem in FiWi contributes in simplifying the network design and enhances the performance in terms of cost efficiency and increased throughput. Several individual-based algorithms, such as Simulated Annealing (SA), Tabu Search, etc. have been suggested for ONU placement, but these algorithms suffer from premature convergence (trapping in a local optima). The present research work undertakes the deployment of FiWi and proposes a novel nature-inspired heuristic paradigm called Moth-Flame optimization (MFO) algorithm for multiple optical network units' placement. MFO is a population based algorithm. Population-based algorithms are better in handling local optima avoidance. The simulation results are compared with the existing Greedy and Simulated Annealing algorithms to optimize the position of ONUs. To the best of our knowledge, MFO algorithm has been used for the first time in this domain, moreover it has been able to provide very promising and competitive results. The performance of MFO algorithm has been analyzed by varying the 'b' parameter. MFO algorithm results in faster convergence than the existing strategies of Greedy and SA and returns a lower value of overall cost function. The results exhibit the dependence of the objective function on the distribution of wireless users also.

  8. Academic Social Networks and Open Access: French Researchers at the Crossroads

    Directory of Open Access Journals (Sweden)

    Christine Okret-Manville

    2016-01-01

    Full Text Available Researchers benefit from an increasing array of tools to enhance direct communication and the dissemination of their research findings. These include Open Access repositories, Open Access journals, or hybrid publishing. For some years, researchers have been using new ways to communicate and share their work by using academic social networks.In an attempt to foster the development of Open Access in France, the French consortium COUPERIN (Unified Consortium of Higher Education and Research Organizations for Access to Numerical Publications proposed that academic social networks could be used to convince researchers of becoming more involved in Open Access. To test this hypothesis, a nationwide survey was launched in 2014 to explore whether and how these academic social networks are used to share content, but also how they compare to other Open Access classic tools. Within a month (20 May to 20 June, 1,898 researchers answered this 28-question survey. It was fully completed by 1,698 of them. This provides COUPERIN with considerable data for analysis. The respondents roughly reflect the composition of the French academic community in terms of gender and research fields, with a slight overrepresentation of young researchers/ PhD candidates.This survey does not, however, cover the in-depth opinions of researchers on Open Access and academic social networks. It therefore only presents general tendencies. Nonetheless, the survey gives many indications as to how researchers apply Open Access. In addition, it shows how they feel about the usefulness of these networks compared to repositories when efficiently disseminating their work. This survey also takes the differences between disciplines into account and characterizes behaviour and opinions according to the different disciplinary communities and their research practices.Finally, this survey allows us to define the main characteristics of a tool which could meet French researchers’ needs for

  9. 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.

  10. One4All Cooperative Media Access Strategy in Infrastructure Based Distributed Wireless Networks

    DEFF Research Database (Denmark)

    Zhang, Qi; Fitzek, Frank H.P.; Iversen, Villy Bæk

    2008-01-01

    a cooperative cluster using their short-range air interface and one device contends the channel for all the devices within the cluster. This strategy reduces the number of mobile devices involved in the collision process for the wireless medium resulting in larger throughput, smaller access delay, and less......In this paper we propose the one4all cooperative access strategy to introduce a more efficient media access strategy for wireless networks. The one4all scheme is designed for the infrastructure based distributed wireless network architecture. The basic idea is that mobile devices can form...... energy consumption. Based on an analytical model, the proposed strategy is compared with the two existing strategies RTS/CTS (request to send/ clear to send) and packet aggregation. The results show that the proposed cooperative scheme has similar throughput performance as packet aggregation and it has...

  11. 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.

  12. 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.

  13. Stability of multiple access network control schemes with carrier sensing and exponential backoff

    Science.gov (United States)

    Barany, Ernest; Krupa, Maciej

    2006-05-01

    A new approach to determine the stability of multiple access network control schemes is presented. A “busy” network (the precise meaning of the term “busy” will be presented in the text) is modelled as a switched single-server hybrid dynamical system whose switching laws are stochastic and are based on typical multiple access network control protocols such as ALOHA and ethernet. The techniques are used to compute the critical ratio of traffic production per network node to total available bandwidth that ensures that data packets will not accumulate unboundedly in waiting queues at each node. This is a measure of stability of the network and is an emergent, global, property determined by decentralized, autonomous behavior of each node. The behavior of each individual node is regarded as “microscopic” and the collective behavior of the network as a whole are emergent consequences of such microscopic laws. The results follow from the stationary distribution property of ergodic Markov chains.

  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. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

    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......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...

  4. 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.

  5. 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

  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. Coalitional Games in Partition Form for Joint Spectrum Sensing and Access in Cognitive Radio Networks

    CERN Document Server

    Saad, Walid; Zheng, Rong; Hjørungnes, Are; Başar, Tamer; Poor, H Vincent

    2012-01-01

    Unlicensed secondary users (SUs) in cognitive radio networks are subject to an inherent tradeoff between spectrum sensing and spectrum access. Although each SU has an incentive to sense the primary user (PU) channels for locating spectrum holes, this exploration of the spectrum can come at the expense of a shorter transmission time, and, hence, a possibly smaller capacity for data transmission. This paper investigates the impact of this tradeoff on the cooperative strategies of a network of SUs that seek to cooperate in order to improve their view of the spectrum (sensing), reduce the possibility of interference among each other, and improve their transmission capacity (access). The problem is modeled as a coalitional game in partition form and an algorithm for coalition formation is proposed. Using the proposed algorithm, the SUs can make individual distributed decisions to join or leave a coalition while maximizing their utilities which capture the average time spent for sensing as well as the capacity achi...

  8. Design and implementation of fingerprint access control system based on ZigBee wireless network

    Directory of Open Access Journals (Sweden)

    Zhang Jin

    2017-01-01

    Full Text Available this paper mainly introduces a kind of fingerprint access control system based on ZigBee wireless network design and implementation method, specify when passengers should fingerprints collected and stored in the system at the information desk PC, and then assign rooms;Guests entered the room according to the fingerprint module, the system will be fingerprint information through ZigBee coordinator node module and network to transmit the fingerprint characteristic value to management system and the fingerprint information stored, if consistent with the electromagnetic lock open, allowed to enter the room, does not conform to the issued a warning sound.Additional access control system can control the corresponding fingerprint information storage room and remove, such as is required for a security incident broke in situation is special open mode can be set up.System software design consists of two aspects of the bottom and upper machine.

  9. 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...... 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...... 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...

  10. Situational Awareness based Risk-Adapatable Access Control in Enterprise Networks

    OpenAIRE

    Lee, Brian; Vanickis, Roman; Rogelio, Franklin; Jacob, Paul

    2017-01-01

    As the computing landscape evolves towards distributed architectures such as Internet of Things (IoT),enterprises are moving away from traditional perimeter based security models toward so called zero trust networking (ZTN) models that treat both the intranet and Internet as equally untrustworthy. Such security models incorporate risk arising from dynamic and situational factors, such as device location and security risk level risk, into the access control decision. Researchers have developed...

  11. Optimizing data access for wind farm control over hierarchical communication networks

    DEFF Research Database (Denmark)

    Madsen, Jacob Theilgaard; Findrik, Mislav; Madsen, Tatiana Kozlova

    2016-01-01

    In this paper we investigate a centralized wind farm controller which runs periodically. The controller attempts to reduce the damage a wind turbine sustains during operation by estimating fatigue based on the wind turbine state. The investigation focuses on the impact of information access...... with respect to the communication network delays. These measurements are done in regards to packet loss and communication delays, and the simulations are rerun using either the traces from the measurements or scenarios constructed from the delay parameters....

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Assessment of micro-regional internal accessibility based on road network

    Science.gov (United States)

    Nie, Ting; Li, Manchun; Jiang, Zhixin; Huang, Kang

    2007-06-01

    Accessibility is an important indicator of regional land-use, social justice and quality of life. It means the convenience from one place to another in a specified kind of transportation system. Wide-region based, most of the present domestic accessibility research took the high-grade highway such as highway and railway as entirely open road, without considering the service that high-grade highway provides based on intersection and railway station. This study extended to put forward arithmetic to deal with this problem in a micro-regional study area. Taking New District, Wuxi City, Jiangsu Province as a study case, this study researched the assessment of micro-regional internal accessibility based on road network including closed road. This study provides a tool to regional economical and social decision, and introduces a new view for studying relationship between people and land-use in micro-district.

  20. Wireless and wireline service convergence in next generation optical access networks - the FP7 WISCON project

    DEFF Research Database (Denmark)

    Vegas Olmos, Juan José; Pang, Xiaodan; Lebedev, Alexander

    2014-01-01

    The next generation of information technology demands both high capacity and mobility for applications such as high speed wireless access capable of supporting broadband services. The transport of wireless and wireline signals is converging into a common telecommunication infrastructure. In this ......The next generation of information technology demands both high capacity and mobility for applications such as high speed wireless access capable of supporting broadband services. The transport of wireless and wireline signals is converging into a common telecommunication infrastructure...... radio-over-fiber (RoF) systems; this is a promising solution to implement broadband seamless wireless -wireline access networks. This project successfully concluded in autumn 2013, and is being follow up by another Marie Curie project entitled “flexible edge nodes for dynamic optical interconnection...

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Support networks and people with physical disabilities: social inclusion and access to health services

    Directory of Open Access Journals (Sweden)

    Cristina Marques de Almeida Holanda

    2015-01-01

    Full Text Available 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.

  6. 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.

  7. 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.

  8. A Novel Architecture for Adaptive Traffic Control in Network on Chip using Code Division Multiple Access Technique

    OpenAIRE

    Fatemeh. Dehghani; Shahram. Darooei

    2016-01-01

    Network on chip has emerged as a long-term and effective method in Multiprocessor System-on-Chip communications in order to overcome the bottleneck in bus based communication architectures. Efficiency and performance of network on chip is so dependent on the architecture and structure of the network. In this paper a new structure and architecture for adaptive traffic control in network on chip using Code Division Multiple Access technique is presented. To solve the problem of synchronous acce...

  9. Experimental validation of a distributed algorithm for dynamic spectrum access in local area networks

    DEFF Research Database (Denmark)

    Tonelli, Oscar; Berardinelli, Gilberto; Tavares, Fernando Menezes Leitão

    2013-01-01

    activities with the Autonomous Component Carrier Selection (ACCS) algorithm, a distributed solution for interference management among small neighboring cells. A preliminary evaluation of the algorithm performance is provided considering its live execution on a software defined radio network testbed......Next generation wireless networks aim at a significant improvement of the spectral efficiency in order to meet the dramatic increase in data service demand. In local area scenarios user-deployed base stations are expected to take place, thus making the centralized planning of frequency resources...... among the cells, a non-viable solution. Cognitive Radio (CR) and Dynamic Spectrum Access (DSA) are the research paradigms which are expected to provide the network nodes the capabilities for an autonomous and efficient selection of the spectrum resources. In this paper we present the first experimental...

  10. On the Evaluation of a Secure Solution to Access 802.11 Networks

    Science.gov (United States)

    da Costa, Fernando; Gaspary, Luciano; Barbosa, Jorge; Cavalheiro, Gerson; Pfitscher, Luciano; Ramos, José Dirceu G.

    Despite offering the possibility to develop and distribute a new set of applications to its users, the widespread and unrestricted use of mobile computing depends on the provisioning of a secure network environment. Regarding the communication established from mobile devices such as PDAs (Personal Digital Assistants), one of the most currently used standards is the IEEE 802.11b, which presents known security flaws. To overcome them, some alternative setups are commonly deployed, based on link, network, transport or application-layer. In this paper we evaluate the impact on data reception rate and energy consumption of IPSec-based PDAs access to 802.11b (WiFi) wireless LANs. As a result of this work we identify the overhead imposed by the security mechanisms and the capacity of the device to run CPU and network-intensive applications.

  11. 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.

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

    OpenAIRE

    Franco Mazzenga; Romeo Giuliano; Francesco Vatalaro

    2017-01-01

    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 net...

  13. The Message Driven File System: A Network Accessible File System for Fine-Grain Message Passing Multicomputers

    Science.gov (United States)

    1996-03-01

    8217·>µ¶´¾¹Ò¶½-§b²e³:¢É²’¤Ñ¯8¼’§9ʵ ½-¯ = ®?> start@ DMAA read@ block 0B sync read@ block 1B send block 0B sync start@ DMAA send block NB read@ block NB...send block N-1C sync start@ DMAA ...D ...D CPUE operationF DMA operationF timeG = ÄH> CPU operationF DMAI operationF copyJ block 0B writeK block 0B

  14. Advanced digital signal processing for short-haul and access network

    Science.gov (United States)

    Zhang, Junwen; Yu, Jianjun; Chi, Nan

    2016-02-01

    Digital signal processing (DSP) has been proved to be a successful technology recently in high speed and high spectrum-efficiency optical short-haul and access network, which enables high performances based on digital equalizations and compensations. In this paper, we investigate advanced DSP at the transmitter and receiver side for signal pre-equalization and post-equalization in an optical access network. A novel DSP-based digital and optical pre-equalization scheme has been proposed for bandwidth-limited high speed short-distance communication system, which is based on the feedback of receiver-side adaptive equalizers, such as least-mean-squares (LMS) algorithm and constant or multi-modulus algorithms (CMA, MMA). Based on this scheme, we experimentally demonstrate 400GE on a single optical carrier based on the highest ETDM 120-GBaud PDM-PAM-4 signal, using one external modulator and coherent detection. A line rate of 480-Gb/s is achieved, which enables 20% forward-error correction (FEC) overhead to keep the 400-Gb/s net information rate. The performance after fiber transmission shows large margin for both short range and metro/regional networks. We also extend the advanced DSP for short haul optical access networks by using high order QAMs. We propose and demonstrate a high speed multi-band CAP-WDM-PON system on intensity modulation, direct detection and digital equalizations. A hybrid modified cascaded MMA post-equalization schemes are used to equalize the multi-band CAP-mQAM signals. Using this scheme, we successfully demonstrates 550Gb/s high capacity WDMPON system with 11 WDM channels, 55 sub-bands, and 10-Gb/s per user in the downstream over 40-km SMF.

  15. Basset: learning the regulatory code of the accessible genome with deep convolutional neural networks.

    Science.gov (United States)

    Kelley, David R; Snoek, Jasper; Rinn, John L

    2016-07-01

    The complex language of eukaryotic gene expression remains incompletely understood. Despite the importance suggested by many noncoding variants statistically associated with human disease, nearly all such variants have unknown mechanisms. Here, we address this challenge using an approach based on a recent machine learning advance-deep convolutional neural networks (CNNs). We introduce the open source package Basset to apply CNNs to learn the functional activity of DNA sequences from genomics data. We trained Basset on a compendium of accessible genomic sites mapped in 164 cell types by DNase-seq, and demonstrate greater predictive accuracy than previous methods. Basset predictions for the change in accessibility between variant alleles were far greater for Genome-wide association study (GWAS) SNPs that are likely to be causal relative to nearby SNPs in linkage disequilibrium with them. With Basset, a researcher can perform a single sequencing assay in their cell type of interest and simultaneously learn that cell's chromatin accessibility code and annotate every mutation in the genome with its influence on present accessibility and latent potential for accessibility. Thus, Basset offers a powerful computational approach to annotate and interpret the noncoding genome. © 2016 Kelley et al.; Published by Cold Spring Harbor Laboratory Press.

  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. 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.

  18. Medium Access Control Protocols for Wireless Sensor Networks with Energy Harvesting

    CERN Document Server

    Iannello, Fabio; Spagnolini, Umberto

    2011-01-01

    The design of Medium Access Control (MAC) protocols for wireless sensor networks (WSNs) has been conventionally tackled by assuming battery-powered devices and by adopting the network lifetime as the main performance criterion. While WSNs operated by energy-harvesting (EH) devices are not limited by network lifetime, they pose new design challenges due to the uncertain amount of harvestable energy. Novel design criteria are thus required to capture the trade-offs between the potentially infinite network lifetime and the uncertain energy availability. This paper addresses the analysis and design of WSNs with EH devices by focusing on conventional MAC protocols, namely TDMA, Framed-ALOHA (FA) and Dynamic-FA (DFA), and by accounting for the performance trade-offs and design issues arising due to EH. A novel metric, referred to as delivery probability, is introduced to measure the capability of a MAC protocol to deliver the measure of any sensor in the network to the intended destination (or fusion center, FC). T...

  19. 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.

  20. 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....

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

    Science.gov (United States)

    Zareei, Mahdi; Islam, A K M Muzahidul; Baharun, Sabariah; Vargas-Rosales, Cesar; Azpilicueta, Leyre; Mansoor, Nafees

    2017-09-16

    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.

  2. 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.

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

    Science.gov (United States)

    Islam, A. K. M. Muzahidul; Baharun, Sabariah; Mansoor, Nafees

    2017-01-01

    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. PMID:28926952

  4. 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.

  5. 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.

  6. Network File - TP Atlas | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available English ]; } else { document.getElementById(lang).innerHTML= '[ Japanese | English ]'; } } window.onload = switchLanguage...at file For CSML (Cell System Markup Language), see also the CSML website. CSML files may be graphically vie

  7. Combining Social Networks and Semantic Web Technologies for Personalizing Web Access

    Science.gov (United States)

    Carminati, Barbara; Ferrari, Elena; Perego, Andrea

    The original purpose of Web metadata was to protect end-users from possible harmful content and to simplify search and retrieval. However they can also be also exploited in more enhanced applications, such as Web access personalization on the basis of end-users’ preferences. In order to achieve this, it is however necessary to address several issues. One of the most relevant is how to assess the trustworthiness of Web metadata. In this paper, we discuss how such issue can be addressed through the use of collaborative and Semantic Web technologies. The system we propose is based on a Web-based Social Network, where members are able not only to specify labels, but also to rate existing labels. Both labels and ratings are then used to assess the trustworthiness of resources’ descriptions and to enforce Web access personalization.

  8. 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.

  9. Design and implementation of the broadband network access system over MoCA

    Science.gov (United States)

    Huang, Jing; Liu, Deming; Wu, Guangsheng

    2009-08-01

    In order to provide a high speed scheme for the access of the "last 100 meters", a composite access scheme of EPON and MoCA is proposed in this paper. At the terminal node of FTTX in EPON system, MoCA technique is used to implement broadband data access by distributing network entering household through Coax. A terminal equipment is designed in this scheme, which can receive the optical signal from the OLT of EPON and transform it into RF signal. The end users will receive the RF signal either from the coaxial cable or a RF antenna. This scheme is particularly applicable for FTTB application.There are many advantages in this system, it can provide a reliable room to room, peer to peer full mesh connectivity of digital content among MoCA devices using existing in-home coaxial cables. Plug and play at the majority of serviceable coax outlets in homes with no need to access or change splitters, or run new cables. What's more, it has higher bandwidth and better management. Two group of tests for the EPON+MoCA system were carried out, one for the coaxial cable and one for wireless. The experimental results showed that the average throughput of the system could reach to approximate 100 Mbps which approach to the theoretical throughput of MoCA 1.0 standard. And the transmission throughput had no remarkable change when the RF antenna replaced the coaxial cable.

  10. Proof-of-Concept System for Opportunistic Spectrum Access in Multi-user Decentralized Networks

    Directory of Open Access Journals (Sweden)

    Sumit J. Darak

    2016-09-01

    Full Text Available Poor utilization of an electromagnetic spectrum and ever increasing demand for spectrum have led to surge of interests in opportunistic spectrum access (OSA based paradigms like cognitive radio and unlicensed LTE. In OSA for decentralized networks, frequency band selection from wideband spectrum is a challenging task since secondary users (SUs do not share any information with each other. In this paper, a new decision making policy (DMP has been proposed for OSA in the multi-user decentralized networks. First contribution is an accurate characterization of frequency bands using Bayes-UCB algorithm. Then, a novel SU orthogonization scheme using Bayes-UCB algorithm is proposed replacing randomization based scheme. At the end, USRP testbed has been developed for analyzing the performance of DMPs using real radio signals. Experimental results show that the proposed DMP offers significant improvement in spectrum utilization, fewer subband switching and collisions compared to other DMPs.

  11. Repeated Auctions with Learning for Spectrum Access in Cognitive Radio Networks

    CERN Document Server

    Han, Zhu; Poor, Vincent H

    2009-01-01

    In this paper, spectrum access in cognitive radio networks is modeled as a repeated auction game subject to monitoring and entry costs. For secondary users, sensing costs are incurred as the result of primary users' activity. Furthermore, each secondary user pays the cost of transmissions upon successful bidding for a channel. Knowledge regarding other secondary users' activity is limited due to the distributed nature of the network. The resulting formulation is thus a dynamic game with incomplete information. In this paper, an efficient bidding learning algorithm is proposed based on the outcome of past transactions. As demonstrated through extensive simulations, the proposed distributed scheme outperforms a myopic one-stage algorithm, and can achieve a good balance between efficiency and fairness.

  12. Proposal of Novel Optical Burst Signal Receiver for ONU in Optical Switched Access Network

    Science.gov (United States)

    Ueda, Hiromi; Hamasaki, Keita; Kuriyama, Takashi; Tsuboi, Toshinori; Kasai, Hiroyuki

    To realize economical optical burst signal receivers for the Optical Network Unit (ONU) of the Ethernet Optical Switched Access Network (E-OSAN), we previously implemented optical burst receivers with AC-coupling and DC-coupling using off-the-shelf components, and showed that the former offers better performance. This paper proposes a new optical burst signal receiver that uses the transfer function, Gn(s) =1-Hn(s), where Hn(s) denotes a Bessel filter transfer function of order n. We also present a method for designing the proposed receiver and clarify that it has better performance than the conventional AC-coupling one. We then present an LCR circuit synthesis of Gn(s), which is necessary to actually implement a burst receiver based on the proposal.

  13. Interoperable Medical Instrument Networking and Access System with Security Considerations for Critical Care

    Directory of Open Access Journals (Sweden)

    Deniz Gurkan

    2010-01-01

    Full Text Available The recent influx of electronic medical records in the health care field, coupled with the need of providing continuous care to patients in the critical care environment, has driven the need for interoperability of medical devices. Open standards are needed to support flexible processes and interoperability of medical devices, especially in intensive care units. In this paper, we present an interoperable networking and access architecture based on the CAN protocol. Predictability of the delay of medical data reports is a desirable attribute that can be realized using a tightly-coupled system architecture. Our simulations on network architecture demonstrate that a bounded delay for event reports offers predictability. In addition, we address security issues related to the storage of electronic medical records. We present a set of open source tools and tests to identify the security breaches, and appropriate measures that can be implemented to be compliant with the HIPAA rules.

  14. 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

    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......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...... 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....

  15. A Cloud-Assisted Random Linear Network Coding Medium Access Control Protocol for Healthcare Applications

    Directory of Open Access Journals (Sweden)

    Elli Kartsakli

    2014-03-01

    Full Text Available Relay sensor networks are often employed in end-to-end healthcare applications to facilitate the information flow between patient worn sensors and the medical data center. Medium access control (MAC protocols, based on random linear network coding (RLNC, are a novel and suitable approach to efficiently handle data dissemination. However, several challenges arise, such as additional delays introduced by the intermediate relay nodes and decoding failures, due to channel errors. In this paper, we tackle these issues by adopting a cloud architecture where the set of relays is connected to a coordinating entity, called cloud manager. We propose a cloud-assisted RLNC-based MAC protocol (CLNC-MAC and develop a mathematical model for the calculation of the key performance metrics, namely the system throughput, the mean completion time for data delivery and the energy efficiency. We show the importance of central coordination in fully exploiting the gain of RLNC under error-prone channels.

  16. Towards convergence of wireless and wireline signal transport in broadband access networks

    DEFF Research Database (Denmark)

    Yu, Xianbin; Prince, Kamau; Tafur Monroy, Idelfonso

    2010-01-01

    Hybrid optical wireless access networks are to play an important role in the realization of the vision of delivery of broadband services to the end-user any time, anywhere and at affordable costs. We present results of experiments conducted over a field deployed optical fibre links we successfully...... demonstrated converged wireless and wireline signal transport over a common fibre infrastructure. The type of signal used in this field deployed experiments cover WiMax, Impulse-radio ultra-wideband (UWB) and coherent transmission of baseband QPSK and radio-over-fibre signals....

  17. Channel capacity of TDD-OFDM-MIMO for multiple access points in a wireless single-frequency-network

    DEFF Research Database (Denmark)

    Takatori, Y.; Fitzek, Frank; Tsunekawa, K.

    2005-01-01

    MIMO data transmission scheme, which combines Single-Frequency-Network (SFN) with TDD-OFDM-MIMO applied for wireless LAN networks. In our proposal, we advocate to use SFN for multiple access points (MAP) MIMO data transmission. The goal of this approach is to achieve very high channel capacity in both...

  18. Reducing the power consumption in LTE-Advanced wireless access networks by a capacity based deployment tool

    Science.gov (United States)

    Deruyck, Margot; Joseph, Wout; Tanghe, Emmeric; Martens, Luc

    2014-09-01

    As both the bit rate required by applications on mobile devices and the number of those mobile devices are steadily growing, wireless access networks need to be expanded. As wireless networks also consume a lot of energy, it is important to develop energy-efficient wireless access networks in the near future. In this study, a capacity-based deployment tool for the design of energy-efficient wireless access networks is proposed. Capacity-based means that the network responds to the instantaneous bit rate requirements of the users active in the selected area. To the best of our knowledge, such a deployment tool for energy-efficient wireless access networks has never been presented before. This deployment tool is applied to a realistic case in Ghent, Belgium, to investigate three main functionalities incorporated in LTE-Advanced: carrier aggregation, heterogeneous deployments, and Multiple-Input Multiple-Output (MIMO). The results show that it is recommended to introduce femtocell base stations, supporting both MIMO and carrier aggregation, into the network (heterogeneous deployment) to reduce the network's power consumption. For the selected area and the assumptions made, this results in a power consumption reduction up to 70%. Introducing femtocell base stations without MIMO and carrier aggregation can already result in a significant power consumption reduction of 38%.

  19. Regulating the access and use of the British gas network; Le modalita` di accesso alla rete britannica

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, Alessandro [RIE Srl, Bologna (Italy)

    1997-03-01

    In the UK the Network Code, regulating the access and use of the British gas network and stating gas transportation companies` rights and duties, has fully come into effect since September 1996: in practice, it comprises all rules applying to BG TransCo, the proper British Gas unit transporting and storing gas on third parties` account.

  20. A heterogeneous approach to achieve QoS in fixed access networks -- results from FP6 project MUSE

    NARCIS (Netherlands)

    Nooren, P.; Deventer, M.O. van; Gamelas, A.; Elizondo, A.J.; Vimel, R.; Eriksson, A.E.

    2005-01-01

    Next-generation networks are composed of different types of access, aggregation and core networks and they are expected to offer a wide range of services. Based on an analysis of the requirements that this heterogeneity introduces for QoS control, this paper concludes that a single QoS solution can

  1. Parity-Check Network Coding for Multiple Access Relay Channel in Wireless Sensor Cooperative Communications

    Directory of Open Access Journals (Sweden)

    Du Bing

    2010-01-01

    Full Text Available A recently developed theory suggests that network coding is a generalization of source coding and channel coding and thus yields a significant performance improvement in terms of throughput and spatial diversity. This paper proposes a cooperative design of a parity-check network coding scheme in the context of a two-source multiple access relay channel (MARC model, a common compact model in hierarchical wireless sensor networks (WSNs. The scheme uses Low-Density Parity-Check (LDPC as the surrogate to build up a layered structure which encapsulates the multiple constituent LDPC codes in the source and relay nodes. Specifically, the relay node decodes the messages from two sources, which are used to generate extra parity-check bits by a random network coding procedure to fill up the rate gap between Source-Relay and Source-Destination transmissions. Then, we derived the key algebraic relationships among multidimensional LDPC constituent codes as one of the constraints for code profile optimization. These extra check bits are sent to the destination to realize a cooperative diversity as well as to approach MARC decode-and-forward (DF capacity.

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

    KAUST Repository

    Douik, Ahmed S.

    2015-09-11

    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 frames across the connected base-stations (BS). The transmitted frame of every BS consists of several time/frequency blocks, called power-zones (PZ), maintained at fixed transmit power. The paper considers the problem of scheduling users to PZs and BSs in a coordinated fashion across the network, by maximizing a network-wide utility under the practical constraint 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 scheduling graph in which each vertex represents an association of users, PZs and BSs. The problem is formulated as a maximum weight clique, in which the weight of each vertex is the benefit of the association represented by that vertex. The paper further presents heuristic algorithms with low computational complexity. Simulation results show the performance of the proposed algorithms and suggest that the heuristics perform near optimal in low shadowing environments. © 2015 IEEE.

  3. The dynamics of socio-connective trust within support networks accessed by informal caregivers.

    Science.gov (United States)

    Ray, Robin A; Street, Annette F

    2011-03-01

    This article introduces the concept of socio-connective trust, the synapse between the social structures and processes that underpin relationships in supportive care networks. Data from an ethnographic case study of 18 informal caregivers providing in-home care for people with life-limiting illness were analysed drawing on theoretical concepts from the work of Giddens and writings on social capital, as well as the construction of trust in the caregiving literature. While conceptions of trust were found to contribute to understanding supportive care relationships, they did not account for the dynamic nature of the availability and use of support networks. Instead, informal caregivers undertook ongoing reflexive negotiation of relationship boundaries in response to their own conception of the current situation and their perception of trust in their relationships with the various members of the support network. The concept of socio-connective trust describes the movement and flow of the flexible bonds that influence relationships among care networks and determine the type and range of support accessed by informal caregivers. Understanding the complexities of socio-connective trust in caregiving relationships will assist health and social care workers to mobilize relevant resources to support informal caregivers.

  4. MetaNET--a web-accessible interactive platform for biological metabolic network analysis.

    Science.gov (United States)

    Narang, Pankaj; Khan, Shawez; Hemrom, Anmol Jaywant; Lynn, Andrew Michael

    2014-01-01

    Metabolic reactions have been extensively studied and compiled over the last century. These have provided a theoretical base to implement models, simulations of which are used to identify drug targets and optimize metabolic throughput at a systemic level. While tools for the perturbation of metabolic networks are available, their applications are limited and restricted as they require varied dependencies and often a commercial platform for full functionality. We have developed MetaNET, an open source user-friendly platform-independent and web-accessible resource consisting of several pre-defined workflows for metabolic network analysis. MetaNET is a web-accessible platform that incorporates a range of functions which can be combined to produce different simulations related to metabolic networks. These include (i) optimization of an objective function for wild type strain, gene/catalyst/reaction knock-out/knock-down analysis using flux balance analysis. (ii) flux variability analysis (iii) chemical species participation (iv) cycles and extreme paths identification and (v) choke point reaction analysis to facilitate identification of potential drug targets. The platform is built using custom scripts along with the open-source Galaxy workflow and Systems Biology Research Tool as components. Pre-defined workflows are available for common processes, and an exhaustive list of over 50 functions are provided for user defined workflows. MetaNET, available at http://metanet.osdd.net , provides a user-friendly rich interface allowing the analysis of genome-scale metabolic networks under various genetic and environmental conditions. The framework permits the storage of previous results, the ability to repeat analysis and share results with other users over the internet as well as run different tools simultaneously using pre-defined workflows, and user-created custom workflows.

  5. Measuring the Gap Between Car and Transit Accessibility : Estimating Access Using a High-Resolution Transit Network Geographic Information System

    NARCIS (Netherlands)

    Benenson, I.; Martens, C.J.C.M.; Rofé, Y.

    2010-01-01

    Accessibility is increasingly identified in the academic literature and in planning practice as a key criterion to assess transport policies and urban land use development. This paper contributes in two respects to the growing body of literature on accessibility and accessibility measurement. First,

  6. Competitive Status Signaling in Peer-to-Peer File-Sharing Networks

    Directory of Open Access Journals (Sweden)

    Henry F. Lyle

    2007-04-01

    Full Text Available Internet peer-to-peer file sharing is a contemporary example of asymmetrical sharing in which “altruists” (file uploaders share unconditionally with non-reciprocating “free riders” (file downloaders. Those who upload digital media files over the Internet risk prosecution for copyright infringement, and are more vulnerable to computer hackers and viruses. In an analysis of file-sharing behavior among university undergraduates (N=331, we found that significantly more males than females engaged in risky file uploading. Contrary to expectations, uploaders were not concerned about their reputation online and file sharers were not interested in identifying or chatting with uploaders while online. Among uploaders, males were more likely than females to be identified as uploaders by friends, to discuss uploading and to upload in the presence of peers. We interpret these results using costly-signaling theory, and argue that uploading is a costly signal in which males engage in avoidable risk taking as a means to compete for status among peers in social contexts other than the Internet.

  7. An Effective Massive Sensor Network Data Access Scheme Based on Topology Control for the Internet of Things

    Directory of Open Access Journals (Sweden)

    Meng Yi

    2016-11-01

    Full Text Available 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.

  8. Fiber-Wireless (FiWi Broadband Access Networks in an Age of Convergence: Past, Present, and Future

    Directory of Open Access Journals (Sweden)

    Martin Maier

    2014-01-01

    Full Text Available After describing the beginnings and state of the art of integrated fiber-wireless (FiWi broadband access networks in great detail, we briefly review recent progress and point to various ongoing research activities, including the design of energy-efficient “green” FiWi access networks, advanced survivability techniques, and integration of wireless and fiber optic sensors, towards realizing adaptable, dependable, and ecoconscious future-proof broadband access networks based on both wireless and shared passive fiber media. Furthermore, we discuss service, application, business, and operation related aspects, which motivate access technology to move into a substantially different direction in the long run than continued capacity provisioning. Given that most 4G cellular mobile network researches so far have been focusing on the achievable performance gains in the wireless front-end only without looking into the details of backhaul implementations and possible backhaul bottlenecks, we identify open key research challenges for FiWi broadband access networks. We explore ways of how they can be deployed across relevant economic sectors other than telecommunications per se, taking major paradigm shifts such as the Third Industrial Revolution, Energy Internet, smart grid, and explosion of mobile data traffic in today’s cellular networks into account.

  9. Beyond the Hypercube: Evolutionary Accessibility of Fitness Landscapes with Realistic Mutational Networks

    Science.gov (United States)

    Zagorski, Marcin; Burda, Zdzislaw; Waclaw, Bartlomiej

    2016-01-01

    Evolutionary pathways describe trajectories of biological evolution in the space of different variants of organisms (genotypes). The probability of existence and the number of evolutionary pathways that lead from a given genotype to a better-adapted genotype are important measures of accessibility of local fitness optima and the reproducibility of evolution. Both quantities have been studied in simple mathematical models where genotypes are represented as binary sequences of two types of basic units, and the network of permitted mutations between the genotypes is a hypercube graph. However, it is unclear how these results translate to the biologically relevant case in which genotypes are represented by sequences of more than two units, for example four nucleotides (DNA) or 20 amino acids (proteins), and the mutational graph is not the hypercube. Here we investigate accessibility of the best-adapted genotype in the general case of K > 2 units. Using computer generated and experimental fitness landscapes we show that accessibility of the global fitness maximum increases with K and can be much higher than for binary sequences. The increase in accessibility comes from the increase in the number of indirect trajectories exploited by evolution for higher K. As one of the consequences, the fraction of genotypes that are accessible increases by three orders of magnitude when the number of units K increases from 2 to 16 for landscapes of size N ∼ 106 genotypes. This suggests that evolution can follow many different trajectories on such landscapes and the reconstruction of evolutionary pathways from experimental data might be an extremely difficult task. PMID:27935934

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

    KAUST Repository

    Radaydeh, Redha M.

    2016-03-28

    © 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 that closed-access small cells (i.e., femtocells) can not reuse available channels, and can serve only active authorized user equipments (UEs). On the other hand, the macrocell base station can unconditionally reuse available channels to serve active macrocell UEs. The analysis characterizes UEs identities, their likelihoods of being active, and their likelihoods of initiating interference. Moreover, it quantifies interference sources observed from effective femtocells considering their over-loaded and under-loaded cell scenarios. The developed results to characterize an active UE performance and the impact of the number of available channels are thoroughly examined. The obtained results are generally applicable for any performance measure and any network channel models. Numerical and simulation examples are presented to clarify the main outcomes of this paper.

  11. 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.

  12. Connectivity and conditional models of access and abundance of species in stream networks.

    Science.gov (United States)

    Chelgren, Nathan D; Dunham, Jason B

    2015-07-01

    Barriers to passage of aquatic organisms at stream road crossings are a major cause of habitat fragmentation in stream networks. Accordingly, large investments have been made to restore passage at these crossings, but often without estimation of population-level benefits. Here, we describe a broad-scale approach to quantifying the effectiveness of passage restoration in terms interpretable at population levels, namely numbers of fish and length of stream gained through restoration, by sampling abundance in a study design that accounts for variable biogeographic species pools, variable stream and barrier configurations, and variable probabilities of capture and detectability for multiple species. We modified an existing zero-inflated negative-binomial model to estimate the probability of site access, abundance conditional on access, and capture probability of individual fish. Therein, we modeled probability of access as a function of gradient, stream road-crossing type, and downstream access by fish simultaneously with a predictive model for abundance at sites accessible to fish. Results indicated that replacement of barriers with new crossing designs intended to allow for greater movement was associated with dramatically higher probability of access for all fishes, including migratory Pacific salmon, trout, sculpin, and lamprey. Conversely, existing non-replaced crossings negatively impacted fish distributions. Assuming no downstream constraints on access, we estimated the potential length of stream restored by the program ranged between 7.33 (lamprey) and 15.28 km (small coastal cutthroat and rainbow trout). These contributions represented a fraction of the total length available upstream (187 km) of replaced crossings. When limited ranges of species were considered, the estimated contributions of culvert replacement were reduced (1.65-km range, for longnose dace to 12.31 km for small coastal cutthroat and rainbow trout). Numbers of fish contributed ranged from

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Layer-specific chromatin accessibility landscapes reveal regulatory networks in adult mouse visual cortex

    Science.gov (United States)

    Gray, Lucas T; Yao, Zizhen; Nguyen, Thuc Nghi; Kim, Tae Kyung; Zeng, Hongkui; Tasic, Bosiljka

    2017-01-01

    Mammalian cortex is a laminar structure, with each layer composed of a characteristic set of cell types with different morphological, electrophysiological, and connectional properties. Here, we define chromatin accessibility landscapes of major, layer-specific excitatory classes of neurons, and compare them to each other and to inhibitory cortical neurons using the Assay for Transposase-Accessible Chromatin with high-throughput sequencing (ATAC-seq). We identify a large number of layer-specific accessible sites, and significant association with genes that are expressed in specific cortical layers. Integration of these data with layer-specific transcriptomic profiles and transcription factor binding motifs enabled us to construct a regulatory network revealing potential key layer-specific regulators, including Cux1/2, Foxp2, Nfia, Pou3f2, and Rorb. This dataset is a valuable resource for identifying candidate layer-specific cis-regulatory elements in adult mouse cortex. DOI: http://dx.doi.org/10.7554/eLife.21883.001 PMID:28112643

  19. 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.

  20. Non-Orthogonal Multiple Access for Large-Scale 5G Networks: Interference Aware Design

    KAUST Repository

    Ali, Konpal S.

    2017-09-18

    Non-orthogonal multiple access (NOMA) is promoted as a key component of 5G cellular networks. As the name implies, NOMA operation introduces intracell interference (i.e., interference arising within the cell) to the cellular operation. The intracell interference is managed by careful NOMA design (e.g., user clustering and resource allocation) along with successive interference cancellation. However, most of the proposed NOMA designs are agnostic to intercell interference (i.e., interference from outside the cell), which is a major performance limiting parameter in 5G networks. This article sheds light on the drastic negative-impact of intercell interference on the NOMA performance and advocates interference-aware NOMA design that jointly accounts for both intracell and intercell interference. To this end, a case study for fair NOMA operation is presented and intercell interference mitigation techniques for NOMA networks are discussed. This article also investigates the potential of integrating NOMA with two important 5G transmission schemes, namely, full duplex and device-to-device communication. This is important since the ambitious performance defined by the 3rd Generation Partnership Project (3GPP) for 5G is foreseen to be realized via seamless integration of several new technologies and transmission techniques.

  1. 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.

  2. 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

  3. 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

  4. Medium access control and hardware prototype designs for low-energy wireless sensor networks

    Energy Technology Data Exchange (ETDEWEB)

    Kohvakka, M.

    2009-07-01

    A Wireless Sensor Network (WSN) is an emerging technology consisting of small, cheap, and ultra-low energy sensor nodes, which cooperatively monitor physical quantities, actuate, and perform data processing tasks. A deployment may comprise thousands of randomly distributed autonomous nodes, which must self-configure and create a multi-hop network topology.This thesis focuses on low-energy WSNs targeting to long network lifetime. The main research problem is the combination of adaptive and scalable multi-hop networking with constrained energy budget, processing power, and communication bandwidth. The research problem is approached by energy-efficient protocols and low-power sensor node platforms. The main contribution of this thesis is an energy-efficient Medium Access Control (MAC) design for TUTWSN (Tampere University of Technology Wireless Sensor Network). The design comprises channel access and networking mechanisms, which specify data exchange, link synchronization, network self-configuration, and neighbor discovery operations. The second outcome are several low-power sensor node platforms, which have been designed and implemented to evaluate the performance of the MAC design and hardware components in real deployments. The third outcome are the performance models and analysis of several MAC designs including TUTWSN, IEEE 802.15.4, and the most essential research proposals.The results and conclusion of this Thesis indicate that it is possible to implement multi-hop WSNs in harsh and dynamic operation conditions with years of lifetime using current low-cost components and batteries. Energy analysis results indicate that the lowest energy consumption is achieved by using simple and high data-rate transceivers. It is also critical to minimize sleep mode power consumption of all components and to use accurate wake-up timers. However, the selection of components constitutes only a minor part of the solution, and an energy-efficient MAC layer design being able to

  5. 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. PMID:23691194

  6. Radiofrequency exposure near an attocell as part of an ultra-high density access network.

    Science.gov (United States)

    Thielens, Arno; Vermeeren, Günter; Caytan, Olivier; Torfs, Guy; Demeester, Piet; Bauwelinck, Johan; Rogier, Hendrik; Martens, Luc; Joseph, Wout

    2017-05-01

    In the future, wireless radiofrequency (RF) telecommunications networks will provide users with gigabit-per-second data rates. Therefore, these networks are evolving toward hybrid networks, which will include commonly used macro- and microcells in combination with local ultra-high density access networks consisting of so-called attocells. The use of attocells requires a proper compliance assessment of exposure to RF electromagnetic radiation. This paper presents, for the first time, such a compliance assessment of an attocell operating at 3.5 GHz with an input power of 1 mW, based on both root-mean-squared electric field strength (Erms ) and peak 10 g-averaged specific absorption rate (SAR10g ) values. The Erms values near the attocell were determined using finite-difference time-domain (FDTD) simulations and measurements by a tri-axial probe. They were compared to the International Commission on Non-Ionizing Radiation Protection's (ICNIRP) reference levels. All measured and simulated Erms values above the attocell were below 5.9 V/m and lower than reference levels. The SAR10g values were measured in a homogeneous phantom, which resulted in an SAR10g of 9.7 mW/kg, and used FDTD simulations, which resulted in an SAR10g of 7.2 mW/kg. FDTD simulations of realistic exposure situations were executed using a heterogeneous phantom, which yielded SAR10g values lower than 2.8 mW/kg. The studied dosimetric quantities were in compliance with ICNIRP guidelines when the attocell was fed an input power <1 mW. The deployment of attocells is thus a feasible solution for providing broadband data transmission without drastically increasing personal RF exposure. Bioelectromagnetics. 38:295-306, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  7. Design of Active Queue Management for Robust Control on Access Router for Heterogeneous Networks

    Directory of Open Access Journals (Sweden)

    Åhlund Christer

    2011-01-01

    Full Text Available The Internet architecture is a packet switching technology that allows dynamic sharing of bandwidth among different flows with in an IP network. Packets are stored and forwarded from one node to the next until reaching their destination. Major issues in this integration are congestion control and how to meet different quality of service requirements associated with various services. In other words streaming media quality degrades with increased packet delay and jitter caused by network congestion. To mitigate the impact of network congestion, various techniques have been used to improve multimedia quality and one of those techniques is Active Queue Management (AQM. Access routers require a buffer to hold packets during times of congestion. A large buffer can absorb the bursty arrivals, and this tends to increase the link utilizations but results in higher queuing delays. Traffic burstiness has a considerable negative impact on network performance. AQM is now considered an effective congestion control mechanism for enhancing transport protocol performance over wireless links. In order to have good link utilization, it is necessary for queues to adapt to varying traffic loads. This paper considers a particular scheme which is called Adaptive AQM (AAQM and studies its performance in the presence of feedback delays and its ability to maintain a small queue length as well as its robustness in the presence of traffic burstiness. The paper also presents a method based on the well-known Markov Modulated Poisson Process (MPP to capture traffic burstiness and buffer occupancy. To demonstrate the generality of the presented method, an analytic model is described and verified by extensive simulations of different adaptive AQM algorithms. The analysis and simulations show that AAQM outperforms the other AQMs with respect to responsiveness and robustness.

  8. Informatics in radiology: integration of the medical imaging resource center into a teaching hospital network to allow single sign-on access.

    Science.gov (United States)

    Prevedello, Luciano M; Andriole, Katherine P; Khorasani, Ryan Roobian Ramin

    2009-01-01

    The RSNA Medical Imaging Resource Center (MIRC) software is an open-source program that allows users to identify, index, and retrieve images, teaching files, and other radiologic data that share a common underlying structure. The software is being continually improved as new challenges and different needs become apparent. Although version T30 is easily installed on a stand-alone computer, its implementation at healthcare enterprises with complex network architecture may be challenging with respect to security because users cannot log on by using a standard enterprise-wide authentication protocol. Instead, authentication takes place through the local MIRC database, creating security concerns and potential organizational problems. In this setting, the Lightweight Directory Access Protocol (LDAP) can be used to provide a single sign-on environment and increase authentication security. A commercial directory service using LDAP has been successfully integrated with MIRC in a large multifacility enterprise to provide single sign-on capability compatible with the institutional networking policies for password security. Copyright RSNA, 2009

  9. System and Network Security Acronyms and Abbreviations

    Science.gov (United States)

    2009-09-01

    Systems Agency DLL dynamic link library DMA direct memory access DMZ demilitarized zone DN distinguished name DN domain name DNP Distributed...NetBIOS Network Basic Input/Output System NetBT NetBIOS over TCP/IP NFAT network forensic analysis tool NFC near field communication NFS network file...Software Reference Library NSS Network Security Services NSTB National SCADA Test Bed NSTISSC National Security Telecommunications and Information

  10. 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.

  11. 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.

  12. Isolated user security enhancement in optical code division multiple access network against eavesdropping

    Science.gov (United States)

    Jyoti, Vishav; Kaler, Rajinder Singh

    2012-09-01

    A novel virtual user system is modeled for enhancing the security of an optical code division multiple access (OCDMA) network. Although the OCDMA system implementing code shift keying (CSK) is secure against a conventional power detector, it is susceptible to differential eavesdropping. An analytical framework is developed for the CSK-OCDMA system to show eavesdropper's code interception performance for a single transmitting user in the presence of a virtual user. It is shown that the eavesdropper's probability of correct bit interception decreases from 7.1×10-1 to 1.85×10-5 with the inclusion of the virtual user. Furthermore, the results confirm that the proposed virtual user scheme increases the confidentiality of the CSK-OCDMA system and outperforms the conventional OCDMA scheme in terms of security.

  13. Enhancing the Performance of Random Access Networks with Random Packet CDMA and Joint Detection

    Directory of Open Access Journals (Sweden)

    Behrouz Farhang-Boroujeny

    2008-09-01

    Full Text Available Random packet CDMA (RP-CDMA is a recently proposed random transmission scheme which has been designed from the beginning as a cross-layer method to overcome the restrictive nature of the Aloha protocol. Herein, we more precisely model its performance and investigate throughput and network stability. In contrast to previous works, we adopt the spread Aloha model for header transmission, and the performance of different joint detection methods for the payload data is investigated. Furthermore, we introduce performance measures for multiple access systems based on the diagonal elements of a modified multipacket reception matrix, and show that our measures describe the upper limit of the vector of stable arrival rates for a finite number of users. Finally, we simulate queue sizes and throughput characteristics of RP-CDMA with various receiver structures and compare them to spread Aloha.

  14. NRZ versus RZ over Absolute Added Correlative coding in optical metro-access networks

    Science.gov (United States)

    Dong-Nhat, Nguyen; Elsherif, Mohamed A.; Le Minh, Hoa; Malekmohammadi, Amin

    2017-03-01

    This paper comparatively investigates the transmission performance of absolute added correlative coding (AACC) using non-return-to-zero (NRZ) and return-to-zero (RZ) pulse shapes with a binary intensity modulation direct detection receiver in 40 Gb/s optical metro-access networks operating at 1550 nm. It is shown that, for AACC transmission, the NRZ impulse shaping is superior in comparison to RZ in spectral efficiency, dispersion tolerance, residual dispersion and self-phase modulation (SPM) tolerance. However, RZ-AACC experiences a 1-2 dB advantage in receiver sensitivity over NRZ-AACC for back-to-back configuration as well as after 300-km single-mode fiber delivery.

  15. Enhancing the Performance of Random Access Networks with Random Packet CDMA and Joint Detection

    Science.gov (United States)

    Kempter, Roland; Amini, Peiman; Farhang-Boroujeny, Behrouz

    2008-12-01

    Random packet CDMA (RP-CDMA) is a recently proposed random transmission scheme which has been designed from the beginning as a cross-layer method to overcome the restrictive nature of the Aloha protocol. Herein, we more precisely model its performance and investigate throughput and network stability. In contrast to previous works, we adopt the spread Aloha model for header transmission, and the performance of different joint detection methods for the payload data is investigated. Furthermore, we introduce performance measures for multiple access systems based on the diagonal elements of a modified multipacket reception matrix, and show that our measures describe the upper limit of the vector of stable arrival rates for a finite number of users. Finally, we simulate queue sizes and throughput characteristics of RP-CDMA with various receiver structures and compare them to spread Aloha.

  16. The Impact of Mobile Offloading on Energy Consumption and Capacity of Radio Access Networks – Case of Finland

    Directory of Open Access Journals (Sweden)

    Michail Katsigiannis

    2015-08-01

    Full Text Available The Finnish Mobile Operators face two main challenges: (i mobile data subscriptions penetration and traffic are experiencing rapid growth; and (ii government intervenes in the market to attain contradictory goals related to extensive high-speed mobile networks and energy consumption reduction. The mobile operators have to increase the capacity in their networks, taking energy efficiency into account. The reduction of energy consumption in mobile networks results to the reducing carbon emissions, and possibly to cost savings. The purpose of this study is to investigate the wide-to-local area offloading in urban regions in Finland and examine the impact of such a network on the wide area access network in terms of energy and capacity. The results show that the capacity relief ranges from 9.7 to 38.7 %, depending on the penetration of local area service, but the energy savings in macro cellular network are negligible.

  17. Real-time Measurements of an Optical Reconfigurable Radio Access Unit for 5G Wireless Access Networks

    DEFF Research Database (Denmark)

    Rodríguez, Sebastián; Morales Vicente, Alvaro; Rommel, Simon

    2017-01-01

    A reconfigurable radio access unit able to switch wavelength, RF carrier frequency and optical path is experimentally demonstrated. The system is able to do the switching processes correctly, while achieving BER values below FEC limit.......A reconfigurable radio access unit able to switch wavelength, RF carrier frequency and optical path is experimentally demonstrated. The system is able to do the switching processes correctly, while achieving BER values below FEC limit....

  18. [Access and comprehensiveness: the viewpoint of users of a mental health network].

    Science.gov (United States)

    de Oliveira, Raimunda Félix; de Andrade, Luiz Odorico Monteiro; Goya, Neusa

    2012-11-01

    This article analyzes user viewpoints regarding mental health care, with a focus on comprehensiveness and access at Psychosocial Care Centers (PCCs). It is a qualitative study with theoretical and methodological references of the Fourth Generation Evaluation and application of the Hermeneutic Dialectic Circle technique. Twelve users of ten mental health services in Fortaleza were interviewed from March to May 2011. Themes of the study were grouped from the narratives, with the hermeneutics of Paul Ricoeur as the benchmark for analysis. The thematic categories were: viewpoints on mental healthcare; conflicts between supply and the subjective need to receive; similarities and differences: from tutelage to autonomy; absence and belonging: open PCCs and non-community centers; between stigma and humanization. The main findings are: the PCCs are seen as spaces for conviviality able to establish affective and social networks; stigma, prejudice and tutelage are present in the services, in their families and in the community; asylum practices persist in alternative services; the humanization of care extends access and bonding in the services; the trajectory of users of the Unified Health System occurs due to their social and health needs.

  19. Directional Medium Access Control (MAC Protocols in Wireless Ad Hoc and Sensor Networks: A Survey

    Directory of Open Access Journals (Sweden)

    David Tung Chong Wong

    2015-06-01

    Full Text Available This survey paper presents the state-of-the-art directional medium access control (MAC protocols in wireless ad hoc and sensor networks (WAHSNs. The key benefits of directional antennas over omni-directional antennas are longer communication range, less multipath interference, more spatial reuse, more secure communications, higher throughput and reduced latency. However, directional antennas lead to single-/multi-channel directional hidden/exposed terminals, deafness and neighborhood, head-of-line blocking, and MAC-layer capture which need to be overcome. Addressing these problems and benefits for directional antennas to MAC protocols leads to many classes of directional MAC protocols in WAHSNs. These classes of directional MAC protocols presented in this survey paper include single-channel, multi-channel, cooperative and cognitive directional MACs. Single-channel directional MAC protocols can be classified as contention-based or non-contention-based or hybrid-based, while multi-channel directional MAC protocols commonly use a common control channel for control packets/tones and one or more data channels for directional data transmissions. Cooperative directional MAC protocols improve throughput in WAHSNs via directional multi-rate/single-relay/multiple-relay/two frequency channels/polarization, while cognitive directional MAC protocols leverage on conventional directional MAC protocols with new twists to address dynamic spectrum access. All of these directional MAC protocols are the pillars for the design of future directional MAC protocols in WAHSNs.

  20. 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.

  1. MAC-Layer Active Dropping for Real-Time Video Streaming in 4G Access Networks

    KAUST Repository

    She, James

    2010-12-01

    This paper introduces a MAC-layer active dropping scheme to achieve effective resource utilization, which can satisfy the application-layer delay for real-time video streaming in time division multiple access based 4G broadband wireless access networks. When a video frame is not likely to be reconstructed within the application-layer delay bound at a receiver for the minimum decoding requirement, the MAC-layer protocol data units of such video frame will be proactively dropped before the transmission. An analytical model is developed to evaluate how confident a video frame can be delivered within its application-layer delay bound by jointly considering the effects of time-varying wireless channel, minimum decoding requirement of each video frame, data retransmission, and playback buffer. Extensive simulations with video traces are conducted to prove the effectiveness of the proposed scheme. When compared to conventional cross-layer schemes using prioritized-transmission/retransmission, the proposed scheme is practically implementable for more effective resource utilization, avoiding delay propagation, and achieving better video qualities under certain conditions.

  2. Energy Efficiency in TDMA-Based Next-Generation Passive Optical Access Networks

    KAUST Repository

    Dhaini, Ahmad R.

    2014-06-01

    Next-generation passive optical network (PON) has been considered in the past few years as a cost-effective broadband access technology. With the ever-increasing power saving concern, energy efficiency has been an important issue in its operations. In this paper, we propose a novel sleep-time sizing and scheduling framework for the implementation of green bandwidth allocation (GBA) in TDMA-PONs. The proposed framework leverages the batch-mode transmission feature of GBA to minimize the overhead due to frequent ONU on-off transitions. The optimal sleeping time sequence of each ONU is determined in every cycle without violating the maximum delay requirement. With multiple ONUs possibly accessing the shared media simultaneously, a collision may occur. To address this problem, we propose a new sleep-time sizing mechanism, namely Sort-And-Shift (SAS), in which the ONUs are sorted according to their expected transmission start times, and their sleep times are shifted to resolve any possible collision while ensuring maximum energy saving. Results show the effectiveness of the proposed framework and highlight the merits of our solutions.

  3. 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.

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

    KAUST Repository

    Douik, Ahmed

    2017-07-17

    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 devices to the frames’ radio resources blocks (RRBs) of the single-antenna base-stations (BSs), adjusting the transmit power levels, and for synchronizing the transmit frames across the connected BSs. Previous studies show that the jointly coordinated scheduling and power control problem in the considered CRAN can be solved using an approach that scales exponentially with the number of BSs, devices, and RRBs, which makes the practical implementation infeasible for reasonably sized networks. This paper instead proposes a low-complexity solution to the problem, under the constraints that each device cannot be served by more than one BS but can be served by multiple RRBs within each BS frame, and under the practical assumption that the channel is constant during the duration of each frame. The paper utilizes graph-theoretical based techniques and shows that constructing a single power control graph is sufficient to obtain the optimal solution with a complexity that is independent of the number of RRBs. Simulation results reveal the optimality of the proposed solution for slow-varying channels, and show that the solution performs near-optimal for highly correlated channels.

  5. Strategies for P2P connectivity in reconfigurable converged wired/wireless access networks.

    Science.gov (United States)

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

    2010-12-06

    This paper presents different strategies to define the architecture of a Radio-Over-Fiber (RoF) Access networks enabling Peer-to-Peer (P2P) functionalities. The architectures fully exploit the flexibility of a wavelength router based on the feedback configuration of an Arrayed Waveguide Grating (AWG) and an optical switch to broadcast P2P services among diverse infrastructures featuring dynamic channel allocation and enabling an optical platform for 3G and beyond wireless backhaul requirements. The first architecture incorporates a tunable laser to generate a dedicated wavelength for P2P purposes and the second architecture takes advantage of reused wavelengths to enable the P2P connectivity among Optical Network Units (ONUs) or Base Stations (BS). While these two approaches allow the P2P connectivity in a one at a time basis (1:1), the third architecture enables the broadcasting of P2P sessions among different ONUs or BSs at the same time (1:M). Experimental assessment of the proposed architecture shows approximately 0.6% Error Vector Magnitude (EVM) degradation for wireless services and 1 dB penalty in average for 1 x 10(-12) Bit Error Rate (BER) for wired baseband services.

  6. 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).

  7. 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.

  8. Joint Distributed Access Point Selection and Power Allocation in Cognitive Radio Networks

    CERN Document Server

    Hong, Mingyi; Alviar, Jorge

    2011-01-01

    Spectrum management has been identified as a crucial step towards enabling the technology of the cognitive radio network (CRN). Most of the current works dealing with spectrum management in the CRN focus on a single task of the problem, e.g., spectrum sensing, spectrum decision, spectrum sharing or spectrum mobility. In this work, we argue that for certain network configurations, jointly performing several tasks of the spectrum management improves the spectrum efficiency. Specifically, we study the uplink resource management problem in a CRN where there exist multiple cognitive users (CUs) and access points (APs), with each AP operates on a set of non-overlapping channels. The CUs, in order to maximize their uplink transmission rates, have to associate to a suitable AP (spectrum decision), and to share the channels belong to this AP with other CUs (spectrum sharing). These tasks are clearly interdependent, and the problem of how they should be carried out efficiently and distributedly is still open in the lit...

  9. Arkansas Special Populations Access Network perception versus reality--cancer screening in primary care clinics.

    Science.gov (United States)

    Rutledge, William; Gibson, Regina; Siegel, Eric; Duke, Kelly; Jones, Rise; Rucinski, Diane; Nunn, Gary; Torrence, W Alvin; Lewellen-Williams, Charlotte; Stewart, Chara; Blann, Kimberly; Belleton, Larry; Fincher, Lindsey; Klimberg, V Suzanne; Greene, Paul; Thomas, Billy; Erwin, Deborah; Henry-Tillman, Ronda

    2006-10-15

    The origin of cancer health disparities and mortality in Arkansas is multifactorial. In response to a cooperative agreement with the National Cancer Institute's Center to Reduce Cancer Health Disparities, the Arkansas Special Populations Access Network (ASPAN) was developed to reduce these disparities. ASPAN's partnership with local primary care physicians of the Arkansas Medical, Dental, and Pharmaceutical Association through the Cancer Education Awareness Program is the focus of this article. A quasi-experimental intervention, the Community Cancer Education Awareness Program, was employed that included 1) physician education to increase awareness of risk factors and cancer screening; and 2) patient education to increase screening, and 3) patient-generated screening questionnaires to prompt discussion of cancer risk and screening recommendations between patients and physicians. Two urban and 2 rural clinics were targeted during a 12-month period with interval intervention assessments. Baseline review of records (n = 200) from patients >/=40 were utilized to assess the rate of breast, prostate, and colorectal screenings among clinics. For the patient education intervention, patients (n = 120) were interviewed via a 34-item assessment. Physician awareness of cancer risk factors and screening recommendations significantly increased. Statistically significant increases were seen for prostate (P = .028), breast (P = .036), and colorectal (P change agent, the ASPAN provider network successfully enhanced cancer screening awareness of minority physicians and their patients. Cancer 2006. (c) 2006 American Cancer Society.

  10. A Spectrum Access Based on Quality of Service (QoS) in Cognitive Radio Networks.

    Science.gov (United States)

    Zhai, Linbo; Wang, Hua; Gao, Chuangen

    2016-01-01

    The quality of service (QoS) is important issue for cognitive radio networks. In the cognitive radio system, the licensed users, also called primary users (PUs), are authorized to utilize the wireless spectrum, while unlicensed users, also called secondary users (SUs), are not authorized to use the wireless spectrum. SUs access the wireless spectrum opportunistically when the spectrum is idle. While SUs use an idle channel, the instance that PUs come back makes SUs terminate their communications and leave the current channel. Therefore, quality of service (QoS) is difficult to be ensured for SUs. In this paper, we first propose an analysis model to obtain QoS for cognitive radio networks such as blocking probability, completed traffic and termination probability of SUs. When the primary users use the channels frequently, QoS of SUs is difficult to be ensured, especially the termination probability. Then, we propose a channel reservation scheme to improve QoS of SUs. The scheme makes the terminated SUs move to the reserved channels and keep on communications. Simulation results show that our scheme can improve QoS of SUs especially the termination probability with a little cost of blocking probability in dynamic environment.

  11. Formats and Network Protocols for Browser Access to 2D Raster Data

    Science.gov (United States)

    Plesea, L.

    2015-12-01

    Tiled web maps in browsers are a major success story, forming the foundation of many current web applications. Enabling tiled data access is the next logical step, and is likely to meet with similar success. Many ad-hoc approaches have already started to appear, and something similar is explored within the Open Geospatial Consortium. One of the main obstacles in making browser data access a reality is the lack of a well-known data format. This obstacle also represents an opportunity to analyze the requirements and possible candidates, applying lessons learned from web tiled image services and protocols. Similar to the image counterpart, a web tile raster data format needs to have good intrinsic compression and be able to handle high byte count data types including floating point. An overview of a possible solution to the format problem, a 2D data raster compression algorithm called Limited Error Raster Compression (LERC) will be presented. In addition to the format, best practices for high request rate HTTP services also need to be followed. In particular, content delivery network (CDN) caching suitability needs to be part of any design, not an after-thought. Last but not least, HTML 5 browsers will certainly be part of any solution since they provide improved access to binary data, as well as more powerful ways to view and interact with the data in the browser. In a simple but relevant application, digital elevation model (DEM) raster data is served as LERC compressed data tiles which are used to generate terrain by a HTML5 scene viewer.

  12. 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

  13. Energy latency tradeoffs for medium access and sleep scheduling in wireless sensor networks

    Science.gov (United States)

    Gang, Lu

    Wireless sensor networks are expected to be used in a wide range of applications from environment monitoring to event detection. The key challenge is to provide energy efficient communication; however, latency remains an important concern for many applications that require fast response. The central thesis of this work is that energy efficient medium access and sleep scheduling mechanisms can be designed without necessarily sacrificing application-specific latency performance. We validate this thesis through results from four case studies that cover various aspects of medium access and sleep scheduling design in wireless sensor networks. Our first effort, DMAC, is to design an adaptive low latency and energy efficient MAC for data gathering to reduce the sleep latency. We propose staggered schedule, duty cycle adaptation, data prediction and the use of more-to-send packets to enable seamless packet forwarding under varying traffic load and channel contentions. Simulation and experimental results show significant energy savings and latency reduction while ensuring high data reliability. The second research effort, DESS, investigates the problem of designing sleep schedules in arbitrary network communication topologies to minimize the worst case end-to-end latency (referred to as delay diameter). We develop a novel graph-theoretical formulation, derive and analyze optimal solutions for the tree and ring topologies and heuristics for arbitrary topologies. The third study addresses the problem of minimum latency joint scheduling and routing (MLSR). By constructing a novel delay graph, the optimal joint scheduling and routing can be solved by M node-disjoint paths algorithm under multiple channel model. We further extended the algorithm to handle dynamic traffic changes and topology changes. A heuristic solution is proposed for MLSR under single channel interference. In the fourth study, EEJSPC, we first formulate a fundamental optimization problem that provides tunable

  14. Inadvertent Exposure to Pornography on the Internet: Implications of Peer-to-Peer File-Sharing Networks for Child Development and Families

    Science.gov (United States)

    Greenfield, P.M.

    2004-01-01

    This essay comprises testimony to the Congressional Committee on Government Reform. The Committee's concern was the possibility of exposure to pornography when children and teens participate in peer-to-peer file-sharing networks, which are extremely popular in these age groups. A review of the relevant literature led to three major conclusions:…

  15. Pharma Pricing & Market Access Europe 2016--Health Network Communications' Tenth Annual Conference (February 23-25, 2016--London, UK).

    Science.gov (United States)

    D'Souza, P

    2016-03-01

    Tighter national budgets and escalating drug prices continue to present challenges for pharmaceutical market access strategies and societal cost of care. As pharmaceutical companies and medical governmental advisory organizations enter tougher negotiations, hospital trusts and other dispensary firms face barriers to receiving the best medical treatment, and as a result patient access is limited. The 2016 HealthNetwork Communications' Pharma Pricing & Market Access Europe meeting brought together pharmaceutical, medical governmental advisory and stakeholders and market access/pricing consultants, to encourage discussions and negotiations into how to improve the drug pricing system and consequential market access strategies while achieving the respective reimbursement and affordability objectives. Copyright 2016 Prous Science, S.A.U. or its licensors. All rights reserved.

  16. 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.

  17. Book Review - V Pogoretskyy, Freedom of Transit and Access to Gas Pipeline Networks Under WTO Law (Cambridge University Press, 2017)

    NARCIS (Netherlands)

    Marhold, Anna

    2017-01-01

    In Freedom of Transit and Access to Pipeline Networks under WTO Law, the author appropriately introduces the topic by stating that energy is featuring increasingly prominently as a topic in international trade law. Indeed, while being a dormant issue in the World Trade Organization (“WTO” forum for

  18. 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

    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...

  19. Performance of Non-Orthogonal Multiple Access (NOMA) in mmWave wireless communications for 5G networks

    DEFF Research Database (Denmark)

    Marcano, Andrea; Christiansen, Henrik Lehrmann

    2017-01-01

    Among the key technologies that have been identified as capacity boosters for fifth generation - 5G - mobile networks, are millimeter wave (mmWave) transmissions and non-orthogonal multiple access (NOMA). The large amount of spectrum available at mmWave frequencies combined with a more effective...

  20. Providing access to research data, publications and current research information at Data Archiving and Networked Services - DANS

    NARCIS (Netherlands)

    Dijk, E.M.S.; Doorn, P.K.

    2014-01-01

    Data Archiving and Networked Services (DANS) promotes sustained access to digital research data in the Netherlands. Researchers can deposit their data through the online archiving system EASY. Via the portal NARCIS the research data are shown in context, namely in relation to publications, and other

  1. Access to Grey Literature in the Netherlands : Grey Literature at Data Archiving and Networked Services – DANS

    NARCIS (Netherlands)

    Dijk, E.M.S.; Doorn, P.K.

    Data Archiving and Networked Services (DANS) is the national Dutch organization for permanent access to research data, with a focus on the humanities and social sciences. DANS offers three services to the scholarly community: DataverseNL, EASY, and NARCIS. DataverseNL is intended to support data

  2. The U.S. Culture Collection Network Responding to the Requirements of the Nagoya Protocol on Access and Benefit Sharing

    Science.gov (United States)

    Kevin McCluskey; Katharine B. Barker; Hazel A. Barton; Kyria Boundy-Mills; Daniel R. Brown; Jonathan A. Coddington; Kevin Cook; Philippe Desmeth; David Geiser; Jessie A. Glaeser; Stephanie Greene; Seogchan Kang; Michael W. Lomas; Ulrich Melcher; Scott E. Miller; David R. Nobles; Kristina J. Owens; Jerome H. Reichman; Manuela da Silva; John Wertz; Cale Whitworth; David Smith; Steven E. Lindow

    2017-01-01

    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...

  3. Improving Accessibility for Seniors in a Life-Long Learning Network: A Usability Study of Learning Websites

    Science.gov (United States)

    Gu, Xiaoqing; Ding, Rui; Fu, Shirong

    2011-01-01

    Senior citizens are comparatively vulnerable in accessing learning opportunities offered on the Internet due to usability problems in current web design. In an effort to build a senior-friendly learning web as a part of the Life-long Learning Network in Shanghai, usability studies of two websites currently available to Shanghai senior citizens…

  4. The PrePRINT Network: A New Dynamic in Information Access from the U.S. Department of Energy.

    Science.gov (United States)

    Traylor, Terry Dennis

    2001-01-01

    Describes the PrePRINT Network, initiated by the Department of Energy to provide access to online preprints and reprints in the sciences and some areas of technological development. Discusses posting preprints on the Internet to improve scientific communication; and explains other Web-based products created to provide scientists with professional…

  5. 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…

  6. The US Culture Collection Network responding to the requirements of the Nagoya Protocol on Access and Benefit Sharing

    Science.gov (United States)

    The US Culture Collection Network held a meeting to share information about how 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 Bio...

  7. Functional classification of the Gauteng provincial road network using the South African road classification and access management manual (TRH26)

    CSIR Research Space (South Africa)

    Veramoothea, P

    2015-08-01

    Full Text Available classification of the Gauteng provincial road network using the South African Road Classification and Access Management Manual (TRH26) as a guideline. In combination with high resolution up-to-date satellite reference imagery, dwelling and building inventories...

  8. Value-Based File Retention: File Attributes as File Value and Information Waste Indicators

    NARCIS (Netherlands)

    Wijnhoven, Alphonsus B.J.M.; Amrit, Chintan Amrit; Dietz, Pim

    2014-01-01

    Several file retention policy methods propose that a file retention policy should be based on file value. Though such a retention policy might increase the value of accessible files, the method to arrive at such a policy is underresearched. This article discusses how one can arrive at a method for

  9. Evaluating the Impact of China’s Rail Network Expansions on Local Accessibility: A Market Potential Approach

    Directory of Open Access Journals (Sweden)

    Wenjie Wu

    2016-05-01

    Full Text Available This paper uses a market potential approach to examine the evolution of the rail transport network of China and its spatial distributional impacts on local accessibility, with a particular focus on high-speed rail improvements. Accessibility is measured by using a “market potential” function that was derived from the general equilibrium model of the economic geography literature, and is empirically calculated based on Geographical Information System (GIS techniques. A key finding, albeit from a highly stylized model, is that rail improvements may help raise territorial polarizing patterns across counties. The results point to the profound implications of railroad network expansion on the accessibility dynamics in periphery regions relative to core regions.

  10. An Efficient Radio Access Control Mechanism for Wireless Network-On-Chip Architectures

    Directory of Open Access Journals (Sweden)

    Maurizio Palesi

    2015-03-01

    Full Text Available Modern systems-on-chip (SoCs today contain hundreds of cores, and this number is predicted to reach the thousands by the year 2020. As the number of communicating elements increases, there is a need for an efficient, scalable and reliable communication infrastructure. As technology geometries shrink to the deep submicron regime, however, the communication delay and power consumption of global interconnections become the major bottleneck. The network-on-chip (NoC design paradigm, based on a modular packet-switched mechanism, can address many of the on-chip communication issues, such as the performance limitations of long interconnects and integration of large number of cores on a chip. Recently, new communication technologies based on the NoC concept have emerged with the aim of improving the scalability limitations of conventional NoC-based architectures. Among them, wireless NoCs (WiNoCs use the radio medium for reducing the performance and energy penalties of long-range and multi-hop communications. As the radio medium can be accessed by a single transmitter at a time, a radio access control mechanism (RACM is needed. In this paper, we present a novel RACM, which allows one to improve both the performance and energy figures of the WiNoC. Experiments, carried out on both synthetic and real traffic scenarios, have shown the effectiveness of the proposed RACM. On average, a 30% reduction in communication delay and a 25% energy savings have been observed when the proposed RACM is applied to a known WiNoC architecture.

  11. Non-Orthogonal Random Access in MIMO Cognitive Radio Networks: Beamforming, Power Allocation, and Opportunistic Transmission.

    Directory of Open Access Journals (Sweden)

    Huifa Lin

    Full Text Available We study secondary random access in multi-input multi-output cognitive radio networks, where a slotted ALOHA-type protocol and successive interference cancellation are used. We first introduce three types of transmit beamforming performed by secondary users, where multiple antennas are used to suppress the interference at the primary base station and/or to increase the received signal power at the secondary base station. Then, we show a simple decentralized power allocation along with the equivalent single-antenna conversion. To exploit the multiuser diversity gain, an opportunistic transmission protocol is proposed, where the secondary users generating less interference are opportunistically selected, resulting in a further reduction of the interference temperature. The proposed methods are validated via computer simulations. Numerical results show that increasing the number of transmit antennas can greatly reduce the interference temperature, while increasing the number of receive antennas leads to a reduction of the total transmit power. Optimal parameter values of the opportunistic transmission protocol are examined according to three types of beamforming and different antenna configurations, in terms of maximizing the cognitive transmission capacity. All the beamforming, decentralized power allocation, and opportunistic transmission protocol are performed by the secondary users in a decentralized manner, thus resulting in an easy implementation in practice.

  12. Energy Efficiency and Capacity Tradeoff in Cloud Radio Access Network of High-Speed Railways

    Directory of Open Access Journals (Sweden)

    Shichao Li

    2017-01-01

    Full Text Available To meet the increasing demand of high-data-rate services of high-speed railway (HSR passengers, cloud radio access network (C-RAN is proposed. This paper investigates the tradeoff between energy efficiency (EE performance and capacity in C-RAN of HSR. Considering that the train location can be predicted, we propose a predictable path loss based time domain power allocation method (PPTPA to improve EE performance of HSR communication system. First, we consider that the communication system of HSR only bears the passenger information services (PISs. The energy-efficient power allocation problem with delay constraint is studied. The formulated problem is nonconvex. To deal with it, an equivalent convex problem is reformulated. Based on PPTPA, we propose an iterative algorithm to improve the EE performance. Second, we consider that the PISs and the train control services (TCSs are all bore. A capacity optimization problem with joint EE and services transmission delay constraints is formulated. Based on PPTPA, we propose a hybrid power allocation scheme to improve the capacity of the system. Finally, we analyze the effect of small-scale fading on EE performance. The effectiveness of the proposed power allocation algorithm is validated by HSR channel measurement trace based emulation results and extensive simulation results.

  13. Non-Orthogonal Random Access in MIMO Cognitive Radio Networks: Beamforming, Power Allocation, and Opportunistic Transmission.

    Science.gov (United States)

    Lin, Huifa; Shin, Won-Yong

    2017-01-01

    We study secondary random access in multi-input multi-output cognitive radio networks, where a slotted ALOHA-type protocol and successive interference cancellation are used. We first introduce three types of transmit beamforming performed by secondary users, where multiple antennas are used to suppress the interference at the primary base station and/or to increase the received signal power at the secondary base station. Then, we show a simple decentralized power allocation along with the equivalent single-antenna conversion. To exploit the multiuser diversity gain, an opportunistic transmission protocol is proposed, where the secondary users generating less interference are opportunistically selected, resulting in a further reduction of the interference temperature. The proposed methods are validated via computer simulations. Numerical results show that increasing the number of transmit antennas can greatly reduce the interference temperature, while increasing the number of receive antennas leads to a reduction of the total transmit power. Optimal parameter values of the opportunistic transmission protocol are examined according to three types of beamforming and different antenna configurations, in terms of maximizing the cognitive transmission capacity. All the beamforming, decentralized power allocation, and opportunistic transmission protocol are performed by the secondary users in a decentralized manner, thus resulting in an easy implementation in practice.

  14. An examination of electronic file transfer between host and microcomputers for the AMPMODNET/AIMNET (Army Material Plan Modernization Network/Acquisition Information Management Network) classified network environment

    Energy Technology Data Exchange (ETDEWEB)

    Hake, K.A.

    1990-11-01

    This report presents the results of investigation and testing conducted by Oak Ridge National Laboratory (ORNL) for the Project Manager -- Acquisition Information Management (PM-AIM), and the United States Army Materiel Command Headquarters (HQ-AMC). It concerns the establishment of file transfer capabilities on the Army Materiel Plan Modernization (AMPMOD) classified computer system. The discussion provides a general context for micro-to-mainframe connectivity and focuses specifically upon two possible solutions for file transfer capabilities. The second section of this report contains a statement of the problem to be examined, a brief description of the institutional setting of the investigation, and a concise declaration of purpose. The third section lays a conceptual foundation for micro-to-mainframe connectivity and provides a more detailed description of the AMPMOD computing environment. It gives emphasis to the generalized International Business Machines, Inc. (IBM) standard of connectivity because of the predominance of this vendor in the AMPMOD computing environment. The fourth section discusses two test cases as possible solutions for file transfer. The first solution used is the IBM 3270 Control Program telecommunications and terminal emulation software. A version of this software was available on all the IBM Tempest Personal Computer 3s. The second solution used is Distributed Office Support System host electronic mail software with Personal Services/Personal Computer microcomputer e-mail software running with IBM 3270 Workstation Program for terminal emulation. Test conditions and results are presented for both test cases. The fifth section provides a summary of findings for the two possible solutions tested for AMPMOD file transfer. The report concludes with observations on current AMPMOD understanding of file transfer and includes recommendations for future consideration by the sponsor.

  15. 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

  16. 77 FR 20810 - Combined Notice of Filings

    Science.gov (United States)

    2012-04-06

    ...: Big Sandy-EQT Capacity Release Waiver Request to be effective N/A. Filed Date: 3/30/12. Accession... and Sales Report of Rockies Express Pipeline LLC. Filed Date: 3/30/12. Accession Number: 20120330-5140.... Description: QEP 37657-15 Amendment to Negotiated Rate Agreement filing to be effective 4/1/2012. Filed Date...

  17. Virtual File System Mounting amp Searching With Network JVM For LAN

    Directory of Open Access Journals (Sweden)

    Nikita Kamble

    2015-08-01

    Full Text Available Computer technology has rapidly grown over past decades. Most of this can be attributed to the Internet as many computers now have a need to be networked together to establish an online connection. A local area network is a group of computers and associated devices that share a common communication line or wireless link to the service. Typically a LAN compasses computers and peripherals connected to a secure server within a small geographic area such as an office building or home computer and other mobile devices that share resources such as printer or network storage. A LAN is contrasted in principle to a wide area networkWANwhich covers a larger geographic distance and may involve leased telecom circuits while the media for LANs are locally managed. Ethernet are twisted pair cabling amp Wi-Fi are the two most common transmission technologies in use for LAN. The rise of virtualization has fueled the development of virtual LANWLANwhich allows network administrator to logically group network nodes amp partition their networks without the need for major infrastructure changes. In some situations a wireless LAN or Wi-Fi maybe preferable to a wired LAN because of its flexibility amp cost. Companies are asserting WLANs as a replacement for their wired infrastructure as the number of smart phones tablets amp other mobile devices proliferates.

  18. Accessing Data Federations with CVMFS

    Science.gov (United States)

    Weitzel, Derek; Bockelman, Brian; Dykstra, Dave; Blomer, Jakob; Meusel, Ren

    2017-10-01

    Data federations have become an increasingly common tool for large collaborations such as CMS and Atlas to efficiently distribute large data files. Unfortunately, these typically are implemented with weak namespace semantics and a non-POSIX API. On the other hand, CVMFS has provided a POSIX-compliant read-only interface for use cases with a small working set size (such as software distribution). The metadata required for the CVMFS POSIX interface is distributed through a caching hierarchy, allowing it to scale to the level of about a hundred thousand hosts. In this paper, we will describe our contributions to CVMFS that merges the data scalability of XRootD-based data federations (such as AAA) with metadata scalability and POSIX interface of CVMFS. We modified CVMFS so it can serve unmodified files without copying them to the repository server. CVMFS 2.2.0 is also able to redirect requests for data files to servers outside of the CVMFS content distribution network. Finally, we added the ability to manage authorization and authentication using security credentials such as X509 proxy certificates. We combined these modifications with the OSGs StashCache regional XRootD caching infrastructure to create a cached data distribution network. We will show performance metrics accessing the data federation through CVMFS compared to direct data federation access. Additionally, we will discuss the improved user experience of providing access to a data federation through a POSIX filesystem.

  19. Challenges on network care considering the perceptions of preceptors of a Pet-Network regarding people with disabilities and at-risk infants: access, comprehensiveness and communication

    Directory of Open Access Journals (Sweden)

    Marta Aoki

    2017-09-01

    Full Text Available Introduction: Health Care Networks (HCN are seen as a possibility for articulating and coordinating actions, health services and is a priority in the health system. One strategy to assure their improvement is the Tutorial Education Program (PET-Redes in the health area. Within this context, it is important to understand the challenges and strengths for the effectiveness of HCN to the network care. Objective: To identify and analyze the perceptions of professionals who are preceptors of PET-Networks (Stork/at-risk infants Network and Disabled People Network about the configuration of the network care and the challenges of professional actions related to it. Method: Qualitative study conducted through two focus groups with professionals that are preceptors of the PET-Networks. Thematic analysis was used for data analysis. Results: Both networks presented the following categories related to the network care configuration: access, comprehensive health care and communication. For this care network configuration, some challenges mentioned include geographical and architectural barriers, lack of social support, lack of transportation, failure on care flow and discontinuities in the communicative process. To deal with these challenges, the following strategies were mentioned: implementation of electronic medical records and formulation of specific forums for debate and articulation of actions, among others. It is important to notice that these categories are intertwined and that more challenges than strategies to overcome them were pointed out by the participants. Conclusion: There are several challenges for effective HCN from different levels and the construction of strategies needs to be convened among all persons involved in the HCN

  20. RADB: Random Access with Differentiated Barring for Latency-Constrained Applications in NB-IoT Network

    OpenAIRE

    Miao, Yiming; Tian, Yuanwen; Cheng, Jingjing; Hossain, M. Shamim; Ghoneim, Ahmed

    2018-01-01

    With the development of LPWA (Low Power Wide Area) technology, the emerging NB-IoT (Narrowband Internet of Things) technology is becoming popular with wide area and low-data-rate services. In order to achieve objectives such as huge amount of connection and wide area coverage within NB-IoT, the problem of network congestion generated by random access of numerous devices should be solved. In this paper, we first introduce the background of NB-IoT and investigate the research on random access o...

  1. Third party access pricing to the network, secondary capacity market and economic optimum: the case of natural gas

    Energy Technology Data Exchange (ETDEWEB)

    David, L.; Percebois, J

    2002-09-01

    The gas deregulation process implies crucial choices concerning access to transportation networks. These choices deal with the nature, the structure and the level of access fees. This paper proposes an evaluation of different systems implemented both in Europe and North America, in relation to normative pricing references. The rules according to which shippers can buy or sell capacity represent another kind of choice that Regulators have to make. This paper proposes a simple model which demonstrates that secondary market prices should not be subject to a cap and emphasizes the need of a 'use-it-or-lose-it' rule on this market. (authors)

  2. National accessibility portal and social networking sites: how to make facebook and twitter work for you

    CSIR Research Space (South Africa)

    Butgereit, L

    2010-05-01

    Full Text Available The National Accessibility Portal (NAP) is a website specifically designed to give South Africans living with disabilities access to important information which may enhance their lives. This information includes lists of schools for children...

  3. 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....

  4. Morning REM Sleep Naps Facilitate Broad Access to Emotional Semantic Networks

    Science.gov (United States)

    Carr, Michelle; Nielsen, Tore

    2015-01-01

    Study Objectives: The goals of the study were to assess semantic priming to emotion and nonemotion cue words using a novel measure of associational breadth for participants who either took rapid eye movement (REM) or nonrapid eye movement (NREM) naps or who remained awake, and to assess the relation of priming to REM sleep consolidation and REM sleep inertia effects. Design: The associational breadth task was applied in both a priming condition, where cue words were signaled to be memorized prior to sleep (primed), and a nonpriming condition, where cue words were not memorized (nonprimed). Cue words were either emotional (positive, negative) or nonemotional. Participants were randomly assigned to either an awake (WAKE) or a sleep condition, which was subsequently split into NREM or REM groups depending on stage at awakening. Setting: Hospital-based sleep laboratory. Participants: Fifty-eight healthy participants (22 male) ages 18 to 35 y (mean age = 23.3 ± 4.08 y). Measurements and Results: The REM group scored higher than the NREM or WAKE groups on primed, but not nonprimed emotional cue words; the effect was stronger for positive than for negative cue words. However, REM time and percent correlated negatively with degree of emotional priming. Priming occurred for REM awakenings but not for NREM awakenings, even when the latter sleep episodes contained some REM sleep. Conclusions: Associational breadth may be selectively consolidated during REM sleep for stimuli that have been tagged as important for future memory retrieval. That priming decreased with REM time and was higher only for REM sleep awakenings is consistent with two explanatory REM sleep processes: REM sleep consolidation serving emotional downregulation and REM sleep inertia. Citation: Carr M, Nielsen T. Morning REM sleep naps facilitate broad access to emotional semantic networks. SLEEP 2015;38(3):433–443. PMID:25409100

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

    National Research Council Canada - National Science Library

    Willemen, Pieter; Laselva, Daniela; Wang, Yu; Kovács, Istvan; Djapic, Relja; Moerman, Ingrid

    2016-01-01

    ...) via controlled loading of these systems. In emerging heterogeneous networks characterized by different cell sizes and diverse WLAN deployments, automatic tuning of the network selection functionality plays a crucial role...

  6. 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

  7. Performance optimization for managing massive numbers of small files in distributed file systems

    OpenAIRE

    Fu, Songling; He, Ligang; Huang, Chenlin; Liao, Xiangke; Li, Kenli

    2014-01-01

    The processing of massive numbers of small files is a challenge in the design of distributed file systems. Currently, the combined-block-storage approach is prevalent. However, the approach employs the traditional file systems such as ExtFS and may cause inefficiency when accessing small files randomly located in the disk. This paper focuses on optimizing the performance of data servers in accessing massive numbers of small files. We present a Flat Lightweight File System (iFlatLFS) to manage...

  8. Power structure among the actors of financial support to the poor to access health services: Social network analysis approach.

    Science.gov (United States)

    Etemadi, Manal; Gorji, Hasan Abolghasem; Kangarani, Hannaneh Mohammadi; Ashtarian, Kioomars

    2017-12-01

    The extent of universal health coverage in terms of financial protection is worrisome in Iran. There are challenges in health policies to guarantee financial accessibility to health services, especially for poor people. Various institutions offer support to ensure that the poor have financial access to health services. The aim of this study is to investigate the relationship network among the institutions active in this field. This study is a policy document analysis. It evaluates the country's legal documents in the field of financial support to the poor for healthcare after the Islamic Revolution in Iran. The researchers looked for the documents on the related websites and referred to the related organizations. The social network analysis approach was chosen for the analysis of the documents. Block-modelling and multi-dimensional scaling (MDS) was used to determine the network structures. The UCINET software was employed to analyse the data. Most the main actors of this network are chosen from the government budget. There is no legal communication and cooperation among some of the actors because of their improper position in the network. Seven blocks have been clustered by CONCOR in terms of the actor's degree of similarity. The social distance among the actors of the seven blocks is very short. Power distribution in the field of financial support to the poor has a fragmented structure; however, it is mainly run by a dominant block consisting of The Supreme Council of Welfare and Social Security, Health Insurance Organization, and the Ministry of Health and Medical Education. The financial support for the poor network involves multiple actors. This variety has created a series of confusions in terms of the type, level, and scope of responsibilities among the actors. The weak presence legislative and regulatory institutions and also non-governmental institutions are the main weak points of this network. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Assessing the implications of cellular network performance on mobile content access

    DEFF Research Database (Denmark)

    Kaup, Fabian; Michelinakis, Foivos; Bui, Nicola

    2016-01-01

    quality is affected by a number of factors, including network operator and available technologies. However, most studies measuring the cellular network do not consider the performance implications of network configuration and management. To this end, this paper reports about an extensive data set...

  10. Accessibility, searchability, transparency and engagement of soil carbon data: The International Soil Carbon Network

    Science.gov (United States)

    Harden, Jennifer W.; Hugelius, Gustaf; Koven, Charlie; Sulman, Ben; O'Donnell, Jon; He, Yujie

    2016-04-01

    Soils are capacitors for carbon and water entering and exiting through land-atmosphere exchange. Capturing the spatiotemporal variations in soil C exchange through monitoring and modeling is difficult in part because data are reported unevenly across spatial, temporal, and management scales and in part because the unit of measure generally involves destructive harvest or non-recurrent measurements. In order to improve our fundamental basis for understanding soil C exchange, a multi-user, open source, searchable database and network of scientists has been formed. The International Soil Carbon Network (ISCN) is a self-chartered, member-based and member-owned network of scientists dedicated to soil carbon science. Attributes of the ISCN include 1) Targeted ISCN Action Groups which represent teams of motivated researchers that propose and pursue specific soil C research questions with the aim of synthesizing seminal articles regarding soil C fate. 2) Datasets to date contributed by institutions and individuals to a comprehensive, searchable open-access database that currently includes over 70,000 geolocated profiles for which soil C and other soil properties. 3) Derivative products resulting from the database, including depth attenuation attributes for C concentration and storage; C storage maps; and model-based assessments of emission/sequestration for future climate scenarios. Several examples illustrate the power of such a database and its engagement with the science community. First, a simplified, data-constrained global ecosystem model estimated a global sensitivity of permafrost soil carbon to climate change (g sensitivity) of -14 to -19 Pg C °C-1 of warming on a 100 years time scale. Second, using mathematical characterizations of depth profiles for organic carbon storage, C at the soil surface reflects Net Primary Production (NPP) and its allotment as moss or litter, while e-folding depths are correlated to rooting depth. Third, storage of deep C is highly

  11. The Cervix Cancer Research Network: Increasing Access to Cancer Clinical Trials in Low- and Middle-Income Countries

    OpenAIRE

    Suneja, Gita; Bacon, Monica; Small, William; Sang Y Ryu; Kitchener, Henry C; Gaffney, David K.

    2015-01-01

    Introduction: The burden of cervical cancer is large and growing in developing countries, due in large part to limited access to screening services and lack of human papillomavirus (HPV) vaccination. In spite of modern advances in diagnostic and therapeutic modalities, outcomes from cervical cancer have not markedly improved in recent years. Novel clinical trials are urgently needed to improve outcomes from cervical cancer worldwide. Methods: The Cervix Cancer Research Network (CCRN), a su...

  12. The Cervix Cancer Research Network (CCRN): Increasing access to cancer clinical trials in low- and middle-income countries

    OpenAIRE

    Gita eSuneja; Monica eBacon; William eSmall; Sang Y Ryu; Kitchener, Henry C; Gaffney, David K.

    2015-01-01

    Introduction: The burden of cervical cancer is large and growing in developing countries, due in large part to limited access to screening services and lack of human papillomavirus (HPV) vaccination. In spite of modern advances in diagnostic and therapeutic modalities, outcomes from cervical cancer have not markedly improved in recent years. Novel clinical trials are urgently needed to improve outcomes from cervical cancer worldwide. Methods: The Cervix Cancer Research Network (CCRN), a sub...

  13. VCSEL-based gigabit IR-UWB link for converged communication and sensing applications in optical metro-access networks

    DEFF Research Database (Denmark)

    Pham, Tien Thang; Gibbon, Timothy Braidwood; Tafur Monroy, Idelfonso

    2012-01-01

    We report on experimental demonstration of an impulse radio ultrawideband (IR-UWB) based converged communication and sensing system. A 1550-nm VCSEL-generated IR-UWB signal is used for 2-Gbps wireless data distribution over 800-m and 50-km single mode fiber links which present short-range in...... application, paving the way forward for the development and deployment of converged UWB VCSEL-based technologies in access and in-building networks of the future....

  14. Enabling technologies for millimeter-wave radio-over-fiber systems in next generation heterogeneous mobile access networks

    Science.gov (United States)

    Zhang, Junwen; Yu, Jianjun; Wang, Jing; Xu, Mu; Cheng, Lin; Lu, Feng; Shen, Shuyi; Yan, Yan; Cho, Hyunwoo; Guidotti, Daniel; Chang, Gee-kung

    2017-01-01

    Fifth-generation (5G) wireless access network promises to support higher access data rate with more than 1,000 times capacity with respect to current long-term evolution (LTE) systems. New radio-access-technologies (RATs) based on higher carrier frequencies to millimeter-wave (MMW) radio-over-fiber, and carrier-aggregation (CA) using multi-band resources are intensively studied to support the high data rate access and effectively use of frequency resources in heterogeneous mobile network (Het-Net). In this paper, we investigate several enabling technologies for MMW RoF systems in 5G Het-Net. Efficient mobile fronthaul (MFH) solutions for 5G centralized radio access network (C-RAN) and beyond are proposed, analyzed and experimentally demonstrated based on the analog scheme. Digital predistortion based on memory polynomial for analog MFH linearization are presented with improved EVM performances and receiver sensitivity. We also propose and experimentally demonstrate a novel inter-/intra- RAT CA scheme for 5G Het- Net. The real-time standard 4G-LTE signal is carrier-aggregated with three broadband 60GHz MMW signals based on proposed optical-domain band-mapping method. RATs based on new waveforms have also been studied here to achieve higher spectral-efficiency (SE) in asynchronous environments. Full-duplex asynchronous quasi-gapless carrier aggregation scheme for MMW ROF inter-/intra-RAT based on the FBMC is also presented with 4G-LTE signals. Compared with OFDM-based signals with large guard-bands, FBMC achieves higher spectral-efficiency with better EVM performance at less received power and smaller guard-bands.

  15. Flexible and Lightweight Access Control for Online Healthcare Social Networks in the Context of the Internet of Things

    Directory of Open Access Journals (Sweden)

    Zhen Qin

    2017-01-01

    Full Text Available Online healthcare social networks (OHSNs play an essential role in sharing information among medical experts and patients who are equipped with similar experiences. To access other patients’ data or experts’ diagnosis anywhere and anytime, it is necessary to integrate the OHSN into the Internet as part of the Internet of Things (IoT. Therefore, it is crucial to design an efficient and versatile access control scheme that can grant and revoke a user to access the OHSN. In this paper, we propose novel attribute-based encryption (ABE features with user revocation and verifiable decryption outsourcing to control the access privilege of the users. The security of the proposed ABE scheme is given in the well-studied random oracle model. With the proposed ABE scheme, the malicious users can be excluded from the system and the user can offload most of the overhead in the decryption to an untrusted cloud server in a verifiable manner. An access control scheme for the OHSN has been given in the context of the IoT based on the proposed ABE scheme. The simulation demonstrates that our access control mechanism is practical.

  16. Geographically weighted regression for modelling the accessibility to the public hospital network in Concepción Metropolitan Area, Chile.

    Science.gov (United States)

    Martínez Bascuñán, Marcela; Rojas Quezada, Carolina

    2016-11-22

    Accessibility models in transport geography based on geographic information systems have proven to be an effective method in determining spatial inequalities associated with public health. This work aims to model the spatial accessibility from populated areas within the Concepción metropolitan area (CMA), the second largest city in Chile. The city's public hospital network is taken into consideration with special reference to socio-regional inequalities. The use of geographically weighted regression (GWR) and ordinary least squares (OLS) for modelling accessibility with socioeconomic and transport variables is proposed. The explanatory variables investigated are: illiterate population, rural housing, alternative housing, homes with a motorised vehicle, public transport routes, and connectivity. Our results identify that approximately 4.1% of the population have unfavourable or very unfavourable accessibility to public hospitals, which correspond to rural areas located south of CMA. Application of a local GWR model (0.87 R2 adjusted) helped to improve the settings over the use of traditional OLS methods (multiple regression) (0.67 R2 adjusted) and to find the spatial distribution of both coefficients of the explanatory variables, demonstrating the local significance of the model. Thus, accessibility studies have enormous potential to contribute to the development of public health and transport policies in turn to achieve equality in spatial accessibility to specialised health care.

  17. Geographically weighted regression for modelling the accessibility to the public hospital network in Concepción Metropolitan Area, Chile

    Directory of Open Access Journals (Sweden)

    Marcela Martínez Bascuñán

    2016-11-01

    Full Text Available Accessibility models in transport geography based on geographic information systems have proven to be an effective method in determining spatial inequalities associated with public health. This work aims to model the spatial accessibility from populated areas within the Concepción metropolitan area (CMA, the second largest city in Chile. The city’s public hospital network is taken into consideration with special reference to socio-regional inequalities. The use of geographically weighted regression (GWR and ordinary least squares (OLS for modelling accessibility with socioeconomic and transport variables is proposed. The explanatory variables investigated are: illiterate population, rural housing, alternative housing, homes with a motorised vehicle, public transport routes, and connectivity. Our results identify that approximately 4.1% of the population have unfavourable or very unfavourable accessibility to public hospitals, which correspond to rural areas located south of CMA. Application of a local GWR model (0.87 R2 adjusted helped to improve the settings over the use of traditional OLS methods (multiple regression (0.67 R2 adjusted and to find the spatial distribution of both coefficients of the explanatory variables, demonstrating the local significance of the model. Thus, accessibility studies have enormous potential to contribute to the development of public health and transport policies in turn to achieve equality in spatial accessibility to specialised health care.

  18. Requirements for a network storage service

    Science.gov (United States)

    Kelly, Suzanne M.; Haynes, Rena A.

    1992-01-01

    Sandia National Laboratories provides a high performance classified computer network as a core capability in support of its mission of nuclear weapons design and engineering, physical sciences research, and energy research and development. The network, locally known as the Internal Secure Network (ISN), was designed in 1989 and comprises multiple distributed local area networks (LAN's) residing in Albuquerque, New Mexico and Livermore, California. The TCP/IP protocol suite is used for inner-node communications. Scientific workstations and mid-range computers, running UNIX-based operating systems, compose most LAN's. One LAN, operated by the Sandia Corporate Computing Directorate, is a general purpose resource providing a supercomputer and a file server to the entire ISN. The current file server on the supercomputer LAN is an implementation of the Common File System (CFS) developed by Los Alamos National Laboratory. Subsequent to the design of the ISN, Sandia reviewed its mass storage requirements and chose to enter into a competitive procurement to replace the existing file server with one more adaptable to a UNIX/TCP/IP environment. The requirements study for the network was the starting point for the requirements study for the new file server. The file server is called the Network Storage Services (NSS) and is requirements are described in this paper. The next section gives an application or functional description of the NSS. The final section adds performance, capacity, and access constraints to the requirements.

  19. 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.

  20. A virtual seed file: the use of multispectral image analysis in the management of genebank seed accessions

    DEFF Research Database (Denmark)

    Adsetts Edberg Hansen, Michael; R. Hay, Fiona; Carstensen, Jens Michael

    2015-01-01

    We present a method for multispectral seed phenotyping as a fast and robust tool for managing genebank accessions. A multispectral vision system was used to take images of the seeds of 20 diverse varieties of rice (approximately 30 seeds for each variety). This was followed by extraction of feature...... information from the images. Multivariate analysis of the feature data was used to classify seed phenotypes according to accession. The proportion of correctly classified rice seeds was 93%. We conclude that the multispectral image analysis could play a role in comparing incoming seeds against existing...... accessions, identifying different seed types within a sample of seeds and/or in checking whether regenerated seeds match the original seeds....

  1. MODERATING EFFECT OF ENTREPRENEURIAL NETWORKING ON THE RELATIONSHIP BETWEEN ACCESS TO FINANCE AND PERFORMANCE OF MICRO AND SMALL ENTERPRISES

    Directory of Open Access Journals (Sweden)

    MUZAFFAR ASAD

    2016-04-01

    Full Text Available The study aim to find the impact of access to finance for improving the performance of MSEs in Punjab, Pakistan. The researchers also try to further estimate the moderating effect of entrepreneurial networking on the relationship between access to finance and performance of MSEs in Punjab, Pakistan. Survey research was employed to collect the data. The data for the study was collected with the help of a questionnaire adapted from the past studies. The reliability of the instrument that was used to collect data was ensured through Cronbach’s alpha and composite reliability. After ensuring the reliability of instrument, structural equation modeling was conducted by using PLS-3. The results of the study supported the arguments raised in the study that there is a positive relationship between access to finance and performance of MSEs in Punjab, Pakistan. The results also supported the argument of moderating effect of entrepreneurial networking on the relationship between access to finance and performance of MSEs in Punjab, Pakistan. The explained variation calculated through R2 has also shown that the overall model is explaining 47.1 % variation in the performance of MSEs in Punjab, Pakistan.

  2. 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.

  3. 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.

  4. Efficient Priority Access to the Shared Commercial Radio with Offloading for Public Safety in LTE Heterogeneous Networks

    Directory of Open Access Journals (Sweden)

    Chafika Tata

    2014-01-01

    Full Text Available This paper presents the algorithm Courteous Priority Access to the shared commercial radio with offloading (CPAwO, for public safety network (PSN over LTE heterogeneous networks (HetNets. We propose a solution for prioritization of PSN users with access to the commercial radio network resources. Our model offers additional radio resources to the PSN. Furthermore, it ensures a certain priority for commercial users by assigning quantities of additional radio resources through the courteous scheme. This allows delaying preemption and blocking bearers when the radio resources are limited. The other part of CPAwO model is to apply the principle of offloading in order to reduce the impact of the macrocell congestion. This technique is to switch the new bearers arriving at the LTE macrocells to small cells, in order to decrease the number of the blocked and interrupted bearers in the network. The results of the simulation showed that the allocation of radio resources via the courteous mechanism with offloading of new bearers to small cells reduces the rate of blocking bearers and delays the preemption of active bearers present in the LTE HetNets. It also reduces the cost of the end-to-end communications, thanks to the reallocation of free frequencies.

  5. Demonstration of flexible and reconfigurable WDM multicast scheme supporting downstream emergency multicast communication for WDM optical access network

    Science.gov (United States)

    Li, Ze; Zhang, Min; Wang, Danshi; Cui, Yue

    2017-09-01

    We propose a flexible and reconfigurable wavelength-division multiplexing (WDM) multicast scheme supporting downstream emergency multicast communication for WDM optical access network (WDM-OAN) via a multicast module (MM) based on four-wave mixing (FWM) in a semiconductor optical amplifier. It serves as an emergency measure to dispose of the burst, large bandwidth, and real-time multicast service with fast service provisioning and high resource efficiency. It also plays the role of physical backup in cases of big data migration or network disaster caused by invalid lasers or modulator failures. It provides convenient and reliable multicast service and emergency protection for WDM-OAN without modifying WDM-OAN structure. The strategies of an MM setting at the optical line terminal and remote node are discussed to apply this scheme to passive optical networks and active optical networks, respectively. Utilizing the proposed scheme, we demonstrate a proof-of-concept experiment in which one-to-six/eight 10-Gbps nonreturn-to-zero-differential phase-shift keying WDM multicasts in both strategies are successfully transmitted over single-mode fiber of 20.2 km. One-to-many reconfigurable WDM multicasts dealing with higher data rate and other modulation formats of multicast service are possible through the proposed scheme. It can be applied to different WDM access technologies, e.g., time-wavelength-division multiplexing-OAN and coherent WDM-OAN, and upgraded smoothly.

  6. Energy Analysis of Contention Tree-Based Access Protocols in Dense Machine-to-Machine Area Networks

    Directory of Open Access Journals (Sweden)

    Francisco Vázquez-Gallego

    2015-01-01

    Full Text Available Machine-to-Machine (M2M area networks aim at connecting an M2M gateway with a large number of energy-constrained devices that must operate autonomously for years. Therefore, attaining high energy efficiency is essential in the deployment of M2M networks. In this paper, we consider a dense M2M area network composed of hundreds or thousands of devices that periodically transmit data upon request from a gateway or coordinator. We theoretically analyse the devices’ energy consumption using two Medium Access Control (MAC protocols which are based on a tree-splitting algorithm to resolve collisions among devices: the Contention Tree Algorithm (CTA and the Distributed Queuing (DQ access. We have carried out computer-based simulations to validate the accuracy of the theoretical models and to compare the energy performance using DQ, CTA, and Frame Slotted-ALOHA (FSA in M2M area networks with devices in compliance with the IEEE 802.15.4 physical layer. Results show that the performance of DQ is totally independent of the number of contending devices, and it can reduce the energy consumed per device in more than 35% with respect to CTA and in more than 80% with respect to FSA.

  7. Next generation WLCG File Transfer Service (FTS)

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    LHC experiments at CERN and worldwide utilize WLCG resources and middleware components to perform distributed computing tasks. One of the most important tasks is reliable file replication. It is a complex problem, suffering from transfer failures, disconnections, transfer duplication, server and network overload, differences in storage systems, etc. To address these problems, EMI and gLite have provided the independent File Transfer Service (FTS) and Grid File Access Library (GFAL) tools. Their development started almost a decade ago, in the meantime, requirements in data management have changed - the old architecture of FTS and GFAL cannot keep support easily these changes. Technology has also been progressing: FTS and GFAL do not fit into the new paradigms (cloud, messaging, for example). To be able to serve the next stage of LHC data collecting (from 2013), we need a new generation of  these tools: FTS 3 and GFAL 2. We envision a service requiring minimal configuration, which can dynamically adapt to the...

  8. Overview of Sparse Graph for Multiple Access in Future Mobile Networks

    Science.gov (United States)

    Lei, Jing; Li, Baoguo; Li, Erbao; Gong, Zhenghui

    2017-10-01

    Multiple access via sparse graph, such as low density signature (LDS) and sparse code multiple access (SCMA), is a promising technique for future wireless communications. This survey presents an overview of the developments in this burgeoning field, including transmitter structures, extrinsic information transform (EXIT) chart analysis and comparisons with existing multiple access techniques. Such technique enables multiple access under overloaded conditions to achieve a satisfactory performance. Message passing algorithm is utilized for multi-user detection in the receiver, and structures of the sparse graph are illustrated in detail. Outlooks and challenges of this technique are also presented.

  9. Analysis of multiuser mixed RF/FSO relay networks for performance improvements in Cloud Computing-Based Radio Access Networks (CC-RANs)

    Science.gov (United States)

    Alimi, Isiaka A.; Monteiro, Paulo P.; Teixeira, António L.

    2017-11-01

    The key paths toward the fifth generation (5G) network requirements are towards centralized processing and small-cell densification systems that are implemented on the cloud computing-based radio access networks (CC-RANs). The increasing recognitions of the CC-RANs can be attributed to their valuable features regarding system performance optimization and cost-effectiveness. Nevertheless, realization of the stringent requirements of the fronthaul that connects the network elements is highly demanding. In this paper, considering the small-cell network architectures, we present multiuser mixed radio-frequency/free-space optical (RF/FSO) relay networks as feasible technologies for the alleviation of the stringent requirements in the CC-RANs. In this study, we use the end-to-end (e2e) outage probability, average symbol error probability (ASEP), and ergodic channel capacity as the performance metrics in our analysis. Simulation results show the suitability of deployment of mixed RF/FSO schemes in the real-life scenarios.

  10. Design considerations for medium access control in resource constrained embedded wireless networks

    OpenAIRE

    Ansari, Junaid

    2012-01-01

    Recent years have experienced a huge influx of daily life applications based on embedded wireless networks. While new applications with more demanding requirements and challenging deployment conditions are being explored, most of the existing networks suffer from communication deficiencies, inefficient use of resources, and inability to satisfy desired quality of service requirements. In order to carry on exploitation and exploration of embedded wireless networks in different daily life appli...

  11. Regional Labour Markets and Job Accessibility in City Network Systems in Germany

    OpenAIRE

    Reggiani, A; Bucci, P.; Russo, G.; Haas, A.; P. Nijkamp

    2011-01-01

    See also the article in the (2011). Volume 19, issue 4, pages 528-536. Commuting is, therefore, an important equilibrating vehicle in a city network constellation. Cities act as attractors of commuters, as most economic activity occurs in cities, thus providing a high share of attractive workplaces. Cities that are centrally connected in a network may act as both centripetal and centrifugal forces in the whole system. The present paper focuses on what is named the City Network (CN) approach. ...

  12. Reduced-complexity adaptive multi-channel assignment for shared access points in over-loaded small-cell networks

    KAUST Repository

    Radaydeh, Redha Mahmoud

    2013-06-01

    This paper proposes a reduced-complexity downlink multi-channel assignment scheme when feedback links are capacity-limited. The system model treats the case when multiple access points are allocated to serve scheduled users in over-loaded (i.e. dense) pico/femtocell networks. It assumes that the deployed access points can be shared simultaneously and employ isotropic antenna arrays of arbitrary sizes. Moreover, they transmit their data on a common physical channel and can not coordinate their transmissions. On the other hand, each scheduled user can be served by single transmit channel from each active access point at a time, and it lacks coordination with concurrent active users. The scheme operates according to the occupancy of available transmit channels, wherein extensively occupied access points are avoided adaptively, while reducing the load of processing. The operation is linked to a target performance via controlling the observed aggregate interference from the projected set of serving points. Through the analysis, results for the scheduled user outage performance, and the average number of active access points are presented. Numerical and simulations studies clarify the gains of the proposed scheme for different operating conditions. © 2013 IEEE.

  13. Traffic-Adaptive, Flow-Specific Medium Access for Wireless Networks

    Science.gov (United States)

    2009-09-01

    51 b. Carrier Sense Multiple Access (CSMA).................................52 c. MACA and MACAW...Figure 17. Comparison of collision avoidance techniques proposed in MACA , MACAW, and MACA -BI (From [132...low power listening lrd ......................long range dependent MAC .................medium access control MACA

  14. A Reinforcement Learning Approach to Access Management in Wireless Cellular Networks

    Directory of Open Access Journals (Sweden)

    Jihun Moon

    2017-01-01

    Full Text Available In smart city applications, huge numbers of devices need to be connected in an autonomous manner. 3rd Generation Partnership Project (3GPP specifies that Machine Type Communication (MTC should be used to handle data transmission among a large number of devices. However, the data transmission rates are highly variable, and this brings about a congestion problem. To tackle this problem, the use of Access Class Barring (ACB is recommended to restrict the number of access attempts allowed in data transmission by utilizing strategic parameters. In this paper, we model the problem of determining the strategic parameters with a reinforcement learning algorithm. In our model, the system evolves to minimize both the collision rate and the access delay. The experimental results show that our scheme improves system performance in terms of the access success rate, the failure rate, the collision rate, and the access delay.

  15. Network analysis reveals the relationship among wood properties, gene expression levels and genotypes of natural Populus trichocarpa accessions.

    Science.gov (United States)

    Porth, Ilga; Klápště, Jaroslav; Skyba, Oleksandr; Friedmann, Michael C; Hannemann, Jan; Ehlting, Juergen; El-Kassaby, Yousry A; Mansfield, Shawn D; Douglas, Carl J

    2013-11-01

    High-throughput approaches have been widely applied to elucidate the genetic underpinnings of industrially important wood properties. Wood traits are polygenic in nature, but gene hierarchies can be assessed to identify the most important gene variants controlling specific traits within complex networks defining the overall wood phenotype. We tested a large set of genetic, genomic, and phenotypic information in an integrative approach to predict wood properties in Populus trichocarpa. Nine-yr-old natural P. trichocarpa trees including accessions with high contrasts in six traits related to wood chemistry and ultrastructure were profiled for gene expression on 49k Nimblegen (Roche NimbleGen Inc., Madison, WI, USA) array elements and for 28,831 polymorphic single nucleotide polymorphisms (SNPs). Pre-selected transcripts and SNPs with high statistical dependence on phenotypic traits were used in Bayesian network learning procedures with a stepwise K2 algorithm to infer phenotype-centric networks. Transcripts were pre-selected at a much lower logarithm of Bayes factor (logBF) threshold than SNPs and were not accommodated in the networks. Using persistent variables, we constructed cross-validated networks for variability in wood attributes, which contained four to six variables with 94-100% predictive accuracy. Accommodated gene variants revealed the hierarchy in the genetic architecture that underpins substantial phenotypic variability, and represent new tools to support the maximization of response to selection. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  16. The U.S. Culture Collection Network Responding to the Requirements of the Nagoya Protocol on Access and Benefit Sharing.

    Science.gov (United States)

    McCluskey, Kevin; Barker, Katharine B; Barton, Hazel A; Boundy-Mills, Kyria; Brown, Daniel R; Coddington, Jonathan A; Cook, Kevin; Desmeth, Philippe; Geiser, David; Glaeser, Jessie A; Greene, Stephanie; Kang, Seogchan; Lomas, Michael W; Melcher, Ulrich; Miller, Scott E; Nobles, David R; Owens, Kristina J; Reichman, Jerome H; da Silva, Manuela; Wertz, John; Whitworth, Cale; Smith, David

    2017-08-15

    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. 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.

  18. Regional Labour Markets and Job Accessibility in City Network Systems in Germany

    NARCIS (Netherlands)

    Reggiani, A.; Bucci, P; Russo, G.; de Haas, A.; Nijkamp, P.

    2011-01-01

    Spatial labour markets are subjected to the forces of regional economic activity and competing network effects. Commuting is, therefore, an important equilibrating vehicle in a City Network constellation. Cities act as attractors of commuters, as most economic activity occurs in cities, thus

  19. Sensors on speaking terms: Schedule-based medium access control protocols for wireless sensor networks

    NARCIS (Netherlands)

    van Hoesel, L.F.W.

    2007-01-01

    Wireless sensor networks make the previously unobservable, observable. The basic idea behind these networks is straightforward: all wires are cut in traditional sensing systems and the sensors are equipped with batteries and radio's to virtually restore the cut wires. The resulting sensors can be

  20. Densely Integrated Photonic Devices based on Microring Resonators in Access Networks

    NARCIS (Netherlands)

    Klein, E.J.; Driessen, A.

    2007-01-01

    The application of optical fibers has led to virtually lossless point to point data links in the core network with practically unlimited bandwidth. In response to increasing bandwidth demands of consumers the optical techniques employed in these networks are now gradually extended towards the

  1. Towards Bandwidth Scalable Transceiver Technology for Optical Metro-Access Networks

    DEFF Research Database (Denmark)

    Spolitis, Sandis; Bobrovs, Vjaceslavs; Wagner, Christoph

    2015-01-01

    Massive fiber-to-the-home network deployment is creating a challenge for telecommunications network operators: exponential increase of the power consumption at the central offices and a never ending quest for equipment upgrades operating at higher bandwidth. In this paper, we report on flexible...

  2. Access management in Safer Transportation Network Planning : safety principles, planning framework, and library information.

    NARCIS (Netherlands)

    Hummel, T.

    2001-01-01

    This report is one in a series of publications, used in the development of the network planning tool ‘Safer Transportation Network Planning’ (Safer-TNP). The publications were used to guide the development of planning structures, diagnostic tools, planning recommendations, and research information

  3. MCBS Access to Care PUF

    Data.gov (United States)

    U.S. Department of Health & Human Services — The MCBS 2013 Access to Care public use file (MCBS PUF) provides the first publically available MCBS file for researchers interested in the health, health care use,...

  4. Seamless Optical Fiber-Wireless Millimeter- Wave Transmission Link for Access Networks

    DEFF Research Database (Denmark)

    Pang, Xiaodan; Lebedev, Alexander; Vegas Olmos, Juan José

    2013-01-01

    This paper presents an experimental demonstration of a millimeter-wave wireless bridge in the W-band for transparent broadband fiber access in the sub-urban areas, where full fiber connections are impracticable....

  5. A New Regulatory Policy for FTTx-Based Next-Generation Access Networks

    Science.gov (United States)

    Makarovič, Boštjan

    2013-07-01

    This article critically assesses the latest European Commission policies in relation to next-generation access investment that put focus on regulated prices and relaxing of wholesale access obligations. Pointing at the vital socio-legal and economic arguments, it further challenges the assumptions of the current EU regulatory framework and calls for a more contractual utility-based model of regulation instead of the current system that overly relies on market-driven infrastructure-based competition.

  6. Telemetry Standards, RCC Standard 106-17, Chapter 27, RF Network Access Layer

    Science.gov (United States)

    2017-07-01

    GIF RPC, PAP, SSL, SQL TCP, UDP, NETBEUI 3. Network 2. Data Link 1. Physical Structuring and managing a multi-node network, including addressing...h0000) for transmission; ignored on reception. 27.5.5 Frame Check Sequence Field A 32-bit FCS shall be computed over the entire MAC frame...rate, LDPC codeblock size, LDPC preamble, ASM sizes, and the goal rate for mission data from the program . The light-pink boxes represent calculated

  7. Simulation and Modeling of a New Medium Access Control Scheme for Multi-Beam Directional Networking

    Science.gov (United States)

    2017-03-03

    implement our protocol in both simula- tion and a new Extendable Mobile Ad -hoc Network Emula- tor (EMANE) model that allows for real-time, high fidelity...issues, where the amount of data passed between the servers is too high, and 2) computation issues, where calculating the interference on the packets...developed a custom discrete event simulator in C++, and a new Ex- tendable Mobile Ad -hoc Network Emulator (EMANE) [10] model. These tools are used to both

  8. VA-Index: Quantifying Assortativity Patterns in Networks with Multidimensional Nodal Attributes (Open Access)

    Science.gov (United States)

    2016-01-27

    comparison. In this work we introduce a novel network metric, which we call VA-index, for quantify- ing the multi-dimensional assortativity. In a nutshell ...network randomization with statistical hypothesis testing. In a nutshell , the intuition of our approach is based on comparing the pairwise average...1)), we would need to normalize the VA-index with the maximum possible average similarity that Fig 2. The computation of VA-index in a nutshell . VA

  9. Predicting Social Networking Site Use and Online Communication Practices among Adolescents: The Role of Access and Device Ownership

    Directory of Open Access Journals (Sweden)

    Drew P. Cingel

    2014-06-01

    Full Text Available Given adolescents' heavy social media use, this study examined a number of predictors of adolescent social media use, as well as predictors of online communication practices. Using data collected from a national sample of 467 adolescents between the ages of 13 and 17, results indicate that demographics, technology access, and technology ownership are related to social media use and communication practices. Specifically, females log onto and use more constructive com-munication practices on Facebook compared to males. Additionally, adolescents who own smartphones engage in more constructive online communication practices than those who share regular cell phones or those who do not have access to a cell phone. Overall, results imply that ownership of mobile technologies, such as smartphones and iPads, may be more predictive of social networking site use and online communication practices than general ownership of technology.

  10. Predicting Social Networking Site Use and Online Communication Practices among Adolescents: The Role of Access and Device Ownership

    Directory of Open Access Journals (Sweden)

    Drew P. Cingel

    2014-01-01

    Full Text Available Given adolescents' heavy social media use, this study examined a number of predictors of adolescent social media use, as well as predictors of online communication practices. Using data collected from a national sample of 467 adolescents between the ages of 13 and 17, results indicate that demographics, technology access, and technology ownership are related to social media use and communication practices. Specifically, females log onto and use more constructive communication practices on Facebook compared to males. Additionally, adolescents who own smartphones engage in more constructive online communication practices than those who share regular cell phones or those who do not have access to a cell phone. Overall, results imply that ownership of mobile technologies, such as smartphones and iPads, may be more predictive of social networking site use and online communication practices than general ownership of technology.

  11. Massive Access Control Aided by Knowledge-Extraction for Co-Existing Periodic and Random Services over Wireless Clinical Networks.

    Science.gov (United States)

    Du, Qinghe; Zhao, Weidong; Li, Weimin; Zhang, Xuelin; Sun, Bo; Song, Houbing; Ren, Pinyi; Sun, Li; Wang, Yichen

    2016-07-01

    The prosperity of e-health is boosted by fast development of medical devices with wireless communications capability such as wearable devices, tiny sensors, monitoring equipments, etc., which are randomly distributed in clinic environments. The drastically-increasing population of such devices imposes new challenges on the limited wireless resources. To relieve this problem, key knowledge needs to be extracted from massive connection attempts dispersed in the air towards efficient access control. In this paper, a hybrid periodic-random massive access (HPRMA) scheme for wireless clinical networks employing ultra-narrow band (UNB) techniques is proposed. In particular, the proposed scheme towards accommodating a large population of devices include the following new features. On one hand, it can dynamically adjust the resource allocated for coexisting periodic and random services based on the traffic load learned from signal collision status. On the other hand, the resource allocation within periodic services is thoroughly designed to simultaneously align with the timing requests of differentiated services. Abundant simulation results are also presented to demonstrate the superiority of the proposed HPRMA scheme over baseline schemes including time-division multiple access (TDMA) and random access approach, in terms of channel utilization efficiency, packet drop ratio, etc., for the support of massive devices' services.

  12. Fencing network direct memory access data transfers in a parallel active messaging interface of a parallel computer

    Science.gov (United States)

    Blocksome, Michael A.; Mamidala, Amith R.

    2015-07-07

    Fencing direct memory access (`DMA`) data transfers in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI including data communications endpoints, each endpoint including specifications of a client, a context, and a task, the endpoints coupled for data communications through the PAMI and through DMA controllers operatively coupled to a deterministic data communications network through which the DMA controllers deliver data communications deterministically, including initiating execution through the PAMI of an ordered sequence of active DMA instructions for DMA data transfers between two endpoints, effecting deterministic DMA data transfers through a DMA controller and the deterministic data communications network; and executing through the PAMI, with no FENCE accounting for DMA data transfers, an active FENCE instruction, the FENCE instruction completing execution only after completion of all DMA instructions initiated prior to execution of the FENCE instruction for DMA data transfers between the two endpoints.

  13. Download this PDF file

    African Journals Online (AJOL)

    PROF. MADUKWE

    and network services at affordable rates. Keywords: ICT .... Many telephone, computer and network ... Table 1: Distribution of respondents according to level of rural farmers' access to ..... power supply, good road network, pipe borne water etc.

  14. WDM Optical Access Network for Full-Duplex and Reconfigurable Capacity Assignment Based on PolMUX Technique

    Directory of Open Access Journals (Sweden)

    Jose Mora

    2014-12-01

    Full Text Available We present a novel bidirectional WDM-based optical access network featuring reconfigurable capacity assignment. The architecture relies on the PolMUX technique allowing a compact, flexible, and bandwidth-efficient router in addition to source-free ONUs and color-less ONUs for cost/complexity minimization. Moreover, the centralized architecture contemplates remote management and control of polarization. High-quality transmission of digital signals is demonstrated through different routing scenarios where all channels are dynamically assigned in both downlink and uplink directions.

  15. 5G Radio Access Network Design - A Brief Overview on the 5G-PPP Project METIS-II

    OpenAIRE

    Marsch, Patrick; Queseth, Olav; El Ayoubi, Salah-Eddine; Maternia, Michał; Uusitalo, Mikko A.; Ruismaki, Rauno; Tesanovic, Milos; Kaloxylos, Alexandros; da Silva, Icaro; Boldi, Mauro

    2015-01-01

    Abstract—The METIS-II project will be an EU-funded project within the 5G Infrastructure Public Private Partnership (5G-PPP) that is dedicated towards an overall 5G radio access network (RAN) design. It will build strongly upon the METIS project, which has laid the foundation for 5G by identifying key scenarios and requirements and determining the most promising technology components and key system design characteristics. However, METIS-II will go significantly further than previous projects b...

  16. 1.25 Gbit/s bidirectional link in an access network employing a reconfigurable optical add/drop multiplexer and a reflective semiconductor optical amplifier

    NARCIS (Netherlands)

    Urban, P.J.; de Laat, M.M.; Klein, E.J.; Koonen, A.M.J.; Khoe, G.D.; de Waardt, H.; Marciniak, M.; Jaworski, M.; Zdabiwicz, M.

    2008-01-01

    In this paper, we demonstrate symmetrical bidirectional transmission of 1.25 Gbit/s wavelength channels in an access network link employing centralized light generation, colourless optical network unit (ONU) and a reconfigurable optical add/drop multiplexer (ROADM). The architecture of ONU is based

  17. 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

    Full Text Available Abstract Background Primary health care is essential in improving and maintaining the health of populations. It has the potential to accelerate achievement of the Millennium Development Goals and fulfill the “Health for All” doctrine of the Alma-Ata Declaration. Understanding the performance of the health system from a geographic perspective is important for improved health planning and evidence-based policy development. The aims of this study were to measure geographical accessibility, model spatial coverage of the existing primary health facility network, estimate the number of primary health facilities working under capacity and the population underserved in the Western Province of Rwanda. Methods This study uses health facility, population and ancillary data for the Western Province of Rwanda. Three different travel scenarios utilized by the population to attend the nearest primary health facility were defined with a maximum travelling time of 60 minutes: Scenario 1 – walking; Scenario 2 – walking and cycling; and Scenario 3 – walking and public transportation. Considering these scenarios, a raster surface of travel time between primary health facilities and population was developed. To model spatial coverage and estimate the number of primary health facilities working under capacity, the catchment area of each facility was calculated by taking into account population coverage capacity, the population distribution, the terrain topography and the travelling modes through the different land categories. Results Scenario 2 (walking and cycling has the highest degree of geographical accessibility followed by Scenario 3 (walking and public transportation. The lowest level of accessibility can be observed in Scenario 1 (walking. The total population covered differs depending on the type of travel scenario. The existing primary health facility network covers only 26.6% of the population in Scenario 1. In Scenario 2, the use of a bicycle

  18. Geographical accessibility and spatial coverage modeling of the primary health care network in the Western Province of Rwanda.

    Science.gov (United States)

    Huerta Munoz, Ulises; Källestål, Carina

    2012-09-17

    Primary health care is essential in improving and maintaining the health of populations. It has the potential to accelerate achievement of the Millennium Development Goals and fulfill the "Health for All" doctrine of the Alma-Ata Declaration. Understanding the performance of the health system from a geographic perspective is important for improved health planning and evidence-based policy development. The aims of this study were to measure geographical accessibility, model spatial coverage of the existing primary health facility network, estimate the number of primary health facilities working under capacity and the population underserved in the Western Province of Rwanda. This study uses health facility, population and ancillary data for the Western Province of Rwanda. Three different travel scenarios utilized by the population to attend the nearest primary health facility were defined with a maximum travelling time of 60 minutes: Scenario 1--walking; Scenario 2--walking and cycling; and Scenario 3--walking and public transportation. Considering these scenarios, a raster surface of travel time between primary health facilities and population was developed. To model spatial coverage and estimate the number of primary health facilities working under capacity, the catchment area of each facility was calculated by taking into account population coverage capacity, the population distribution, the terrain topography and the travelling modes through the different land categories. Scenario 2 (walking and cycling) has the highest degree of geographical accessibility followed by Scenario 3 (walking and public transportation). The lowest level of accessibility can be observed in Scenario 1 (walking). The total population covered differs depending on the type of travel scenario. The existing primary health facility network covers only 26.6% of the population in Scenario 1. In Scenario 2, the use of a bicycle greatly increases the population being served to 58% of inhabitants

  19. Impairments Computation for Routing Purposes in a Transparent-Access Optical Network Based on Optical CDMA and WDM

    Science.gov (United States)

    Musa, Ahmed

    2016-06-01

    Optical access networks are becoming more widespread and the use of multiple services might require a transparent optical network (TON). Multiplexing and privacy could benefit from the combination of wavelength division multiplexing (WDM) and optical coding (OC) and wavelength conversion in optical switches. The routing process needs to be cognizant of different resource types and characteristics such as fiber types, fiber linear impairments such as attenuation, dispersion, etc. as well as fiber nonlinear impairments such as four-wave mixing, cross-phase modulation, etc. Other types of impairments, generated by optical nodes or photonic switches, also affect the signal quality (Q) or the optical signal to noise ratio (OSNR), which is related to the bit error rate (BER). Therefore, both link and switch impairments must be addressed and somehow incorporated into the routing algorithm. However, it is not practical to fully integrate all photonic-specific attributes in the routing process. In this study, new routing parameters and constraints are defined that reflect the distinct characteristics of photonic networking. These constraints are applied to the design phase of TON and expressed as a cost or metric form that will be used in the network routing algorithm.

  20. Channel access delay and buffer distribution of two-user opportunistic scheduling schemes in wireless networks

    KAUST Repository

    Hossain, Md Jahangir

    2010-07-01

    In our earlier works, we proposed rate adaptive hierarchical modulation-assisted two-best user opportunistic scheduling (TBS) and hybrid two-user scheduling (HTS) schemes. The proposed schemes are innovative in the sense that they include a second user in the transmission opportunistically using hierarchical modulations. As such the frequency of information access of the users increases without any degradation of the system spectral efficiency (SSE) compared to the classical opportunistic scheduling scheme. In this paper, we analyze channel access delay of an incoming packet at the base station (BS) buffer when our proposed TBS and HTS schemes are employed at the BS. Specifically, using a queuing analytic model we derive channel access delay as well as buffer distribution of the packets that wait at BS buffer for down-link (DL) transmission. We compare performance of the TBS and HTS schemes with that of the classical single user opportunistic schemes namely, absolute carrier-to-noise ratio (CNR)-based single user scheduling (ASS) and normalized CNR-based single user scheduling (NSS). For an independent and identically distributed (i.i.d.) fading environment, our proposed scheme can improve packet\\'s access delay performance compared to the ASS. Selected numerical results in an independent but non-identically distributed (i.n.d.) fading environment show that our proposed HTS achieves overall good channel access delay performance. © 2010 IEEE.

  1. Threats and risks to information security: a practical analysis of free access wireless networks

    Science.gov (United States)

    Quirumbay, Daniel I.; Coronel, Iván. A.; Bayas, Marcia M.; Rovira, Ronald H.; Gromaszek, Konrad; Tleshova, Akmaral; Kozbekova, Ainur

    2017-08-01

    Nowadays, there is an ever-growing need to investigate, consult and communicate through the internet. This need leads to the intensification of free access to the web in strategic and functional points for the benefit of the community. However, this open access is also related to the increase of information insecurity. The existing works on computer security primarily focus on the development of techniques to reduce cyber-attacks. However, these approaches do not address the sector of inexperienced users who have difficulty understanding browser settings. Two methods can solve this problem: first the development of friendly browsers with intuitive setups for new users and on the other hand, by implementing awareness programs on essential security without deepening on technical information. This article addresses an analysis of the vulnerabilities of wireless equipment that provides internet service in the open access zones and the potential risks that could be found when using these means.

  2. Describing the Access Network by means of Router Buffer Modelling: A New Methodology

    Directory of Open Access Journals (Sweden)

    Luis Sequeira

    2014-01-01

    Full Text Available The behaviour of the routers’ buffer may affect the quality of service (QoS of network services under certain conditions, since it may modify some traffic characteristics, as delay or jitter, and may also drop packets. As a consequence, the characterization of the buffer is interesting, especially when multimedia flows are transmitted and even more if they transport information with real-time requirements. This work presents a new methodology with the aim of determining the technical and functional characteristics of real buffers (i.e., behaviour, size, limits, and input and output rate of a network path. It permits the characterization of intermediate buffers of different devices in a network path across the Internet.

  3. Accessing Data Transfer Reliability for Duty Cycled Mobile Wireless Sensor Network

    Directory of Open Access Journals (Sweden)

    Faisal Karim Shaikh

    2014-01-01

    Full Text Available Mobility in WSNs (Wireless Sensor Networks introduces significant challenges which do not arise in static WSNs. Reliable data transport is an important aspect of attaining consistency and QoS (Quality of Service in several applications of MWSNs (Mobile Wireless Sensor Networks. It is important to understand how each of the wireless sensor networking characteristics such as duty cycling, collisions, contention and mobility affects the reliability of data transfer. If reliability is not managed well, the MWSN can suffer from overheads which reduce its applicability in the real world. In this paper, reliability assessment is being studied by deploying MWSN in different indoor and outdoor scenarios with various duty cycles of the motes and speeds of the mobile mote. Results show that the reliability is greatly affected by the duty cycled motes and the mobility using inherent broadcast mechanisms.

  4. Untangling complex networks: risk minimization in financial markets through accessible spin glass ground states.

    Science.gov (United States)

    Lisewski, Andreas Martin; Lichtarge, Olivier

    2010-08-15

    Recurrent international financial crises inflict significant damage to societies and stress the need for mechanisms or strategies to control risk and tamper market uncertainties. Unfortunately, the complex network of market interactions often confounds rational approaches to optimize financial risks. Here we show that investors can overcome this complexity and globally minimize risk in portfolio models for any given expected return, provided the relative margin requirement remains below a critical, empirically measurable value. In practice, for markets with centrally regulated margin requirements, a rational stabilization strategy would be keeping margins small enough. This result follows from ground states of the random field spin glass Ising model that can be calculated exactly through convex optimization when relative spin coupling is limited by the norm of the network's Laplacian matrix. In that regime, this novel approach is robust to noise in empirical data and may be also broadly relevant to complex networks with frustrated interactions that are studied throughout scientific fields.

  5. Non-Orthogonal Multiple Access and Carrierless Amplitude Phase Modulation for 5G Mobile Networks

    DEFF Research Database (Denmark)

    Altabas, Jose A.; Rommel, Simon; Puerta Ramírez, Rafael

    2017-01-01

    A combined NOMA and multiCAP scheme is proposed for capacity enhancement of 5G mobile networks and experimentally tested over a W-band millimeter-wave radio-over-fiber system. The evaluated NOMA-CAP system provides an aggregated transmission rate of 30Gbps.......A combined NOMA and multiCAP scheme is proposed for capacity enhancement of 5G mobile networks and experimentally tested over a W-band millimeter-wave radio-over-fiber system. The evaluated NOMA-CAP system provides an aggregated transmission rate of 30Gbps....

  6. Distance-Based Access Modifiers Applied to Safety in Home Networks

    DEFF Research Database (Denmark)

    Mortensen, Kjeld Høyer; Schougaard, Kari Rye; Schultz, Ulrik Pagh

    2004-01-01

    Home networks and the interconnection of home appliances is a classical theme in ubiquitous computing research. Security is a recurring concern, but there is a lack of awareness of safety: preventing the computerized house from harming the inhabitants, even in a worst-case scenario where...... be performed within a physical proximity that ensures safety. We use a declarative approach integrated with an IDL language to express location-based restrictions on operations. This model has been implemented in a middleware for home audio-video devices, using infrared communication and a local-area network...

  7. World-wide interactive access to scientific databases via satellite and terrestrial data network

    Science.gov (United States)

    Sanderson, T. R.; Albrecht, M. A.; Ciarlo, A.; Brett, M.; Blank, K.; Hughes, P. M. T.; Wallum, G.; Hills, H. K.; Green, J. L.; Mcguire, R. E.; hide

    1990-01-01

    In order to demonstrate the possibilities for scientific networking and data transfer, a first temporary satellite network link was installed between Czecholovakia and the European space operations center in Darmstadt, during the meeting of the inter-agency consultative group for space science in Prague. Several experiments to show interactive nature of the facility and the capability of the system were carried out, and it was proven that, despite the temporary nature of the installation, the planned demonstrations could be conducted in real time. Demonstrations included electronic mail message, orbit prediction and solar X-ray data. The results of the experiment provided insight into possibilities of data exchange.

  8. On the Modeling and Analysis of Heterogeneous Radio Access Networks using a Poisson Cluster Process

    DEFF Research Database (Denmark)

    Suryaprakash, Vinay; Møller, Jesper; Fettweis, Gerhard P.

    processes, some of which are alluded to (later) in this paper. We model a heterogeneous network consisting of two types of base stations by using a particular Poisson cluster process model. The main contributions are two-fold. First, a complete description of the interference in heterogeneous networks...... is derived in the form of its Laplace functional. Second, using an asymptotic convergence result which was shown in our previous work, we derive the expressions for the mean and variance of the distribution to which the interference converges. The utility of this framework is discussed for both...

  9. 76 FR 45788 - Combined Notice of Filings

    Science.gov (United States)

    2011-08-01

    ...: Big Sandy LINK Implementation to be effective 9/1/2011. Filed Date: 07/14/2011. Accession Number...: ETNG Modifications for Big Sandy LINK Implementation to be effective 9/1/2011. Filed Date: 07/14/2011... Big Sandy LINK Implementation to be effective 9/1/2011. Filed Date: 07/14/2011. Accession Number...

  10. 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

  11. Page 1 r Stability of multiple access communication networks 379 de ...

    Indian Academy of Sciences (India)

    Mosely J. Humblet P A 1985 A class of efficient contention resolution algorithms for multiple access. IEEE Trans. Connur. COM-33: 45-5. Nelson R 1984 The stochastic cusp, swallowtail and hyperbolic umbilic catastrophes as manifest in a simple communications model. Performance'84 (Amsterdam: Elsevier Science ...

  12. 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...

  13. HACMAC: A reliable human activity-based medium access control for implantable body sensor networks

    NARCIS (Netherlands)

    Karuppiah Ramachandran, Vignesh Raja; Havinga, Paul J.M.; Meratnia, Nirvana

    Chronic care is an eminent application of implantable body sensor networks (IBSN). Performing physical activities such as walking, running, and sitting is unavoidable during the long-term monitoring of chronic-care patients. These physical activities cripple the radio frequency (RF) signal between

  14. 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, wav...

  15. Biobjective Optimization of Radio Access Technology Selection and Resource Allocation in Heterogeneous Wireless Networks

    DEFF Research Database (Denmark)

    Zakrzewska, Anna; D’Andreagiovanni, Fabio; Ruepp, Sarah Renée

    2013-01-01

    We propose a novel optimization model for resource assignment in heterogeneous wireless network. The model adopts two objective functions maximizing the number of served users and the minimum granted utility at once. A distinctive feature of our new model is to consider two consecutive time slots...

  16. Accessing English and Networks at an English-Medium Multicultural Church in East Canada: An Ethnography

    Science.gov (United States)

    Han, Huamei

    2014-01-01

    Drawing from a larger ethnography of skilled Chinese immigrants' language learning during settlement in Toronto, this article explores the role of informal interactions in facilitating immigrants learning English as a second language and settlement. Examining various activities and networks available at an English-medium multicultural church, this…

  17. Cross-layer design for radio resource allocation based on priority scheduling in OFDMA wireless access network

    Directory of Open Access Journals (Sweden)

    Chen Yen-Wen

    2011-01-01

    Full Text Available Abstract The orthogonal frequency-division multiple access (OFDMA system has the advantages of flexible subcarrier allocation and adaptive modulation with respect to channel conditions. However, transmission overhead is required in each frame to broadcast the arrangement of radio resources to all mobile stations within the coverage of the same base station. This overhead greatly affects the utilization of valuable radio resources. In this paper, a cross layer scheme is proposed to reduce the number of traffic bursts at the downlink of an OFDMA wireless access network so that the overhead of the media access protocol (MAP field can be minimized. The proposed scheme considers the priorities and the channel conditions of quality of service (QoS traffic streams to arrange for them to be sent with minimum bursts in a heuristic manner. In addition, the trade-off between the degradation of the modulation level and the reduction of traffic bursts is investigated. Simulation results show that the proposed scheme can effectively reduce the traffic bursts and, therefore, increase resource utilization.

  18. Stability Properties of Network Diversity Multiple Access with Multiple-Antenna Reception and Imperfect Collision Multiplicity Estimation

    Directory of Open Access Journals (Sweden)

    Ramiro Samano-Robles

    2013-01-01

    Full Text Available In NDMA (network diversity multiple access, protocol-controlled retransmissions are used to create a virtual MIMO (multiple-input multiple-output system, where collisions can be resolved via source separation. By using this retransmission diversity approach for collision resolution, NDMA is the family of random access protocols with the highest potential throughput. However, several issues remain open today in the modeling and design of this type of protocol, particularly in terms of dynamic stable performance and backlog delay. This paper attempts to partially fill this gap by proposing a Markov model for the study of the dynamic-stable performance of a symmetrical and non-blind NDMA protocol assisted by a multiple-antenna receiver. The model is useful in the study of stability aspects in terms of the backlog-user distribution and average backlog delay. It also allows for the investigation of the different states of the system and the transition probabilities between them. Unlike previous works, the proposed approach considers the imperfect estimation of the collision multiplicity, which is a crucial process to the performance of NDMA. The results suggest that NDMA improves not only the throughput performance over previous solutions, but also the average number of backlogged users, the average backlog delay and, in general, the stability of random access protocols. It is also shown that when multiuser detection conditions degrade, ALOHA-type backlog retransmission becomes relevant to the stable operation of NDMA.

  19. The Zika Contraception Access Network: a feasibility programme to increase access to contraception in Puerto Rico during the 2016-17 Zika virus outbreak.

    Science.gov (United States)

    Lathrop, Eva; Romero, Lisa; Hurst, Stacey; Bracero, Nabal; Zapata, Lauren B; Frey, Meghan T; Rivera, Maria I; Berry-Bibee, Erin N; Honein, Margaret A; Monroe, Judith; Jamieson, Denise J

    2018-02-01

    Prevention of unintended pregnancy is a primary strategy to reduce adverse pregnancy and birth outcomes related to Zika virus infection. The Zika Contraception Access Network (Z-CAN) aimed to build a network of health-care providers offering client-centred contraceptive counselling and the full range of reversible contraception at no cost to women in Puerto Rico who chose to prevent pregnancy during the 2016-17 Zika virus outbreak. Here, we describe the Z-CAN programme design, implementation activities, and baseline characteristics of the first 21 124 participants. Z-CAN was developed by establishing partnerships between federal agencies, territorial health agencies, private corporations, and domestic philanthropic and non-profit organisations in the continental USA and Puerto Rico. Private donations to the National Foundation for the Centers for Disease Control and Prevention (CDCF) secured a supply of reversible contraceptive methods (including long-acting reversible contraception), made available to non-sterilised women of reproductive age at no cost through provider reimbursements and infrastructure supported by the CDCF. To build capacity in contraception service provision, doctors and clinic staff from all public health regions and nearly all municipalities in Puerto Rico were recruited into the programme. All providers completed 1 day of comprehensive training in contraception knowledge, counselling, and initiation and management, including the insertion and removal of long-acting reversible contraceptives (LARCs). Z-CAN was announced through health-care providers, word of mouth, and a health education campaign. Descriptive characteristics of programme providers and participants were recorded, and we estimated the factors associated with choosing and receiving a LARC method. As part of a Z-CAN programme monitoring plan, participants were invited to complete a patient satisfaction survey about whether they had obtained free, same-day access to their chosen

  20. A Novel Approach to Reduce the Unicast Bandwidth of an IPTV System in a High-Speed Access Network

    Directory of Open Access Journals (Sweden)

    El Hassane Khabbiza

    2017-01-01

    Full Text Available Channel change time is a critical quality of experience (QOE metric for IP-based video delivery systems such as Internet Protocol Television (IPTV. An interesting channel change acceleration scheme based on peer-assisted delivery was recently proposed, which consists of deploying one FCC server (Fast Channel Change Server in the IP backbone in order to send the unicast stream to the STB (Set-Top Box before sending the normal multicast stream after each channel change. However, deploying such a solution will cause high bandwidth usage in the network because of the huge unicast traffic sent by the FCC server to the STBs. In this paper, we propose a new solution to reduce the bandwidth occupancy of the unicast traffic, by deploying the FCC server capabilities on the user STB. This means that, after each channel change request, the STB will receive the unicast traffic from another STB instead of the central server. By using this method, the unicast traffic will not pass through the IP network; it will be a peer-to-peer communication via the Access Network only. Extensive simulation results are presented to demonstrate the robustness of our new solution.

  1. Scalable Video Streaming for Single-Hop Wireless Networks Using a Contention-Based Access MAC Protocol

    Directory of Open Access Journals (Sweden)

    Monchai Lertsutthiwong

    2008-07-01

    Full Text Available Limited bandwidth and high packet loss rate pose a serious challenge for video streaming applications over wireless networks. Even when packet loss is not present, the bandwidth fluctuation, as a result of an arbitrary number of active flows in an IEEE 802.11 network, can significantly degrade the video quality. This paper aims to enhance the quality of video streaming applications in wireless home networks via a joint optimization of video layer-allocation technique, admission control algorithm, and medium access control (MAC protocol. Using an Aloha-like MAC protocol, we propose a novel admission control framework, which can be viewed as an optimization problem that maximizes the average quality of admitted videos, given a specified minimum video quality for each flow. We present some hardness results for the optimization problem under various conditions and propose some heuristic algorithms for finding a good solution. In particular, we show that a simple greedy layer-allocation algorithm can perform reasonably well, although it is typically not optimal. Consequently, we present a more expensive heuristic algorithm that guarantees to approximate the optimal solution within a constant factor. Simulation results demonstrate that our proposed framework can improve the video quality up to 26% as compared to those of the existing approaches.

  2. Reducing Latency in Internet Access Links with Mechanisms in Endpoints and within the Network

    OpenAIRE

    Khademi, Naeem

    2015-01-01

    Excessive and unpredictable end-to-end latency is a major problem for today’s Internet performance, affecting a range of applications from real-time multimedia to web traffic. This is mainly attributed to the interaction between the TCP congestion control mechanism and the unmanaged large buffers deployed across the Internet. This dissertation investigates transport and link layer solutions to solve the Internet’s latency problem on the access links. These solutions operate on the sender side...

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

    OpenAIRE

    Khloussy, Elissar; Jiang, Yuming

    2018-01-01

    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 ...

  4. Cross-layer Control for Adaptive Video Streaming over Wireless Access Networks

    OpenAIRE

    Abdallah AbouSheaisha, Abdallah Sabry

    2016-01-01

    Over the last decade, the wide deployment of wireless access technologies (e.g. WiFi, 3G, and LTE) and the remarkable growth in the volume of streaming video content have significantly altered the telecommunications field. These developments introduce new challenges to the research community including the need to develop new solutions (e.g. traffic models and transport protocols) to address changing traffic patterns and the characteristics of wireless links and the need for new evaluation me...

  5. Untangling complex networks: Risk minimization in financial markets through accessible spin glass ground states

    Science.gov (United States)

    Lisewski, Andreas Martin; Lichtarge, Olivier

    2010-08-01

    Recurrent international financial crises inflict significant damage to societies and stress the need for mechanisms or strategies to control risk and tamper market uncertainties. Unfortunately, the complex network of market interactions often confounds rational approaches to optimize financial risks. Here we show that investors can overcome this complexity and globally minimize risk in portfolio models for any given expected return, provided the margin requirement remains below a critical, empirically measurable value. In practice, for markets with centrally regulated margin requirements, a rational stabilization strategy would be keeping margins small enough. This result follows from ground states of the random field spin glass Ising model that can be calculated exactly through convex optimization when relative spin coupling is limited by the norm of the network’s Laplacian matrix. In that regime, this novel approach is robust to noise in empirical data and may be also broadly relevant to complex networks with frustrated interactions that are studied throughout scientific fields.

  6. Multiconnectivity for Mobility Robustness in Standalone 5G Ultra Dense Networks with Intrafrequency Cloud Radio Access

    Directory of Open Access Journals (Sweden)

    Fasil B. Tesema

    2017-01-01

    Full Text Available Capacity and ultra-reliable communication are some of the requirements for 5th generation (5G networks. One of the candidate technologies to satisfy capacity requirement is standalone Ultra Dense Network (UDN. However, UDNs are characterized by fast change of received signal strength that creates mobility challenges in terms of increased handovers and connection failures. In this paper, a low layer multiconnectivity scheme is presented for standalone UDN aiming at ultra-reliable communication that is free of interruptions from handover procedures and connection failures. Furthermore, the problem in managing of the set of serving cells, that are involved in multiconnectivity for each user, is formulated. By using numerical method, feasible scheme for management of the set of serving cells is derived. Performance of the proposed multiconnectivity scheme is evaluated and compared against single connectivity. It is shown that the proposed multiconnectivity scheme outperforms single connectivity considerably in terms of connection failures and cell-edge throughput.

  7. Bio-Inspired Dynamic Radio Access in Cognitive Networks based on Social Foraging Swarms

    OpenAIRE

    di Lorenzo, Paolo

    2012-01-01

    There is strong trend, in current research on communication and sensor networks, to study selforganizing, self-healing systems. This poses great challenges to the research on decentralized systems, but at the same offers great potentials for future developments, especially in view of the current trend towards miniaturized systems. Even if the development of self-organizing systems is probably at the beginning, biological systems offers many examples of self-organization and ...

  8. Simulation and Modeling of a Novel Medium Access Control Scheme for Multi-Beam Directional Networking

    Science.gov (United States)

    2017-03-03

    several novel MAC features are added that allow for robust communication, such as location tracking and tracking neighbor’s transmit or receive state. For...this paper, we implement this protocol in both simula- tion and a new Extendable Mobile Ad -hoc Network Emula- tor (EMANE) model that allows for real...infrastructure issues, where the amount of data passed between the servers is too high, and 2) computation issues, where calculating the interference on the

  9. Heterogeneous radio-over-fiber passive access network architecture to mitigate Rayleigh backscattering interferometric beat noise.

    Science.gov (United States)

    Yeh, C H; Chow, C W

    2011-03-28

    We propose and experimentally demonstrate a hybrid radio-over-fiber (ROF) wavelength division multiplexed and time division multiplexed passive optical network (WDM-TDM PON) architecture to mitigate Rayleigh backscattering (RB) interferometric beat noises. Here, only a single wavelength is needed at the central office (CO) to generate the downstream baseband data for optical wired application and optical millimeter-wave (mm-wave) signal for wireless application. The upstream signal is produced by remodulating the downstream signal. No optical filter is required at the optical network unit/remote antenna unit (ONU/RAU) to separate the optical wired and optical mm-wave signals. In the proposed network, 10 Gb/s differential phase shift keying (DPSK) signal is used for the downstream optical wired application and 2.5 Gb/s on-off keying (OOK) signal on 20 GHz carrier is used for the optical mm-wave signal. In each ONU, a reflective optical semiconductor amplifier (RSOA) is used to remodulate and produce a 2.5 Gb/s OOK format for upstream traffic. As the back-refection produced by the downstream DPSK signal and the upstream OOK signal is traveling in different fiber path, RB noise at the CO can be completely mitigated.

  10. An Authentication and Key Management Mechanism for Resource Constrained Devices in IEEE 802.11-based IoT Access Networks

    Directory of Open Access Journals (Sweden)

    Ki-Wook Kim

    2017-09-01

    Full Text Available Many Internet of Things (IoT services utilize an IoT access network to connect small devices with remote servers. They can share an access network with standard communication technology, such as IEEE 802.11ah. However, an authentication and key management (AKM mechanism for resource constrained IoT devices using IEEE 802.11ah has not been proposed as yet. We therefore propose a new AKM mechanism for an IoT access network, which is based on IEEE 802.11 key management with the IEEE 802.1X authentication mechanism. The proposed AKM mechanism does not require any pre-configured security information between the access network domain and the IoT service domain. It considers the resource constraints of IoT devices, allowing IoT devices to delegate the burden of AKM processes to a powerful agent. The agent has sufficient power to support various authentication methods for the access point, and it performs cryptographic functions for the IoT devices. Performance analysis shows that the proposed mechanism greatly reduces computation costs, network costs, and memory usage of the resource-constrained IoT device as compared to the existing IEEE 802.11 Key Management with the IEEE 802.1X authentication mechanism.

  11. An Authentication and Key Management Mechanism for Resource Constrained Devices in IEEE 802.11-based IoT Access Networks.

    Science.gov (United States)

    Kim, Ki-Wook; Han, Youn-Hee; Min, Sung-Gi

    2017-09-21

    Many Internet of Things (IoT) services utilize an IoT access network to connect small devices with remote servers. They can share an access network with standard communication technology, such as IEEE 802.11ah. However, an authentication and key management (AKM) mechanism for resource constrained IoT devices using IEEE 802.11ah has not been proposed as yet. We therefore propose a new AKM mechanism for an IoT access network, which is based on IEEE 802.11 key management with the IEEE 802.1X authentication mechanism. The proposed AKM mechanism does not require any pre-configured security information between the access network domain and the IoT service domain. It considers the resource constraints of IoT devices, allowing IoT devices to delegate the burden of AKM processes to a powerful agent. The agent has sufficient power to support various authentication methods for the access point, and it performs cryptographic functions for the IoT devices. Performance analysis shows that the proposed mechanism greatly reduces computation costs, network costs, and memory usage of the resource-constrained IoT device as compared to the existing IEEE 802.11 Key Management with the IEEE 802.1X authentication mechanism.

  12. 76 FR 30333 - Combined Notice of Filings

    Science.gov (United States)

    2011-05-25

    ... Report filings: Docket Numbers: RP11-2051-000. Applicants: Black Marlin Pipeline Company. Description: Report of Black Marlin Pipeline Company. Filed Date: 04/28/2011. Accession Number: 20110428-5219. Comment...

  13. Communication technology access, use, and preferences among primary care patients: from the Residency Research Network of Texas (RRNeT).

    Science.gov (United States)

    Hill, Jason H; Burge, Sandra; Haring, Anna; Young, Richard A

    2012-01-01

    The digital revolution is changing the manner in which patients communicate with their health care providers, yet many patients still lack access to communication technology. We conducted this study to evaluate access to, use of, and preferences for using communication technology among a predominantly low-income patient population. We determined whether access, use, and preferences were associated with type of health insurance, sex, age, and ethnicity. In 2011, medical student researchers administered questionnaires to patients of randomly selected physicians within 9 primary care clinics in the Residency Research Network of Texas. Surveys addressed access to and use of cell phones and home computers and preferences for communicating with health care providers. In this sample of 533 patients (77% response rate), 448 (84%) owned a cell phone and 325 (62%) owned computers. Only 48% reported conducting Internet searches, sending and receiving E-mails, and looking up health information on the Internet. Older individuals, those in government sponsored insurance programs, and individuals from racial/ethnic minority groups had the lowest levels of technology adoption. In addition, more than 60% of patients preferred not to send and receive health information over the Internet, by instant messaging, or by text messaging. Many patients in this sample did not seek health information electronically nor did they want to communicate electronically with their physicians. This finding raises concerns about the vision of the patient-centered medical home to enhance the doctor-patient relationship through communication technology. Our patients represent some of the more vulnerable populations in the United States and, as such, deserve attention from health care policymakers who are promoting widespread use of communication technology.

  14. Analytic Network Process on Financial Access of the Small and Medium Enterprise in Sharia Banking in Tasikmalaya City

    Directory of Open Access Journals (Sweden)

    Asep Suryanto

    2016-02-01

    Full Text Available Small and Medium Enterprise (SME has a significant role in national economic development. The increase of Small and Medium Enterprise is followed by the rise in employment absorbment and equity in income distribution. The capital constraint and the impedance of banking financial access have become the main problem to the Small and Medium entrepreneurs. The objectives of this research: 1 To identify the main factors as problems of Small and Medium Enterprises in having access to the financial institutions.2 To find the solutions of the research problems. This research used qualitative approach i.e. Analytic Network Process (ANP. For applying this method, it is expected to help the researchers in making measurement and sinthesis of some factors regarding the topic analyzed as well as finding the solution for problems faced by the SMEs. Data used in this research is primary data collected from questionaires and indepth interview with experts, practitioners, SMEs and regulators which then analyzed by structuringthe hierarchi into homogen clusters of the SMEs problems and solutions, measuring into ratio scale and building sinthesis. As the result, it becomes clear what factors impeding the financial access of the SMEs to banks. The results of this research shows that the difficulties of SMEs in accessing financial support in islamic financial institutions are internal problems of islamic banking i.e. 1 lack of financial assistance given to the SMEs, 2 the functions of islamic banking as business partners for SMEs is not optimal. Whereas the external problems in the SMEs is the disability in meeting the financial requirements asked by islamic banking that is collateral and business history. The solutions are: 1 internal solution; islamic banking should give business mentoring to SMEs that have received financial supports to minimalize the bad credits level. 2 external solution; the government should socialize islamic financial mechanism to SMEs as

  15. An Analytical Network Process on Financial Access of the Small and Medium Enterprise in Sharia Banking in Tasikmalaya City

    Directory of Open Access Journals (Sweden)

    Asep Suryanto

    2015-06-01

    Full Text Available Small and Medium Enterprise (SME is one of the significant roles in national economic development. It is seemly followed by the rise of employment absorbent and equity in income distribution. The capital constraint and the impedance of banking financial access have become the main problem to the Small and Medium entrepreneurs. The objectives of this research are to identify the main factors as problems of Small and Medium Enterprises in having access to the financial institutions, and also to find out the solutions of the research problems. This research uses qualitative approach i.e. Analytic Network Process (ANP. Through applying this method, it is expected to help the researchers in making measurement and synthesis of some factors regarding on the topic analyzed as well as finding the solution for problems faced by the SMEs. The resources of the data is derived from questionnaires and in-depth interview with experts, practitioners, SMEs and regulators which then analyzed by the structure and hierarchy into homogen clusters of the SMEs problems and solutions, measuring into ratio scale and building synthesis. As the result, it becomes clear what factors impeding the financial access of the SMEs to banks. The results of this research show that the difficulties of SMEs in accessing financial support in Islamic financial institutions are internal problems of Islamic banking i.e. lack of financial assistance given to the SMEs, the functions of Islamic banking as business partners for SMEs is not optimal. Whereas the external problems in the SMEs are the disability in meeting the financial requirements asked by Islamic banking that are collateral and business history. The internal solutions are Islamic banking must give business mentoring to SMEs that have received financial supports to minimalize the bad credits level. The external solution is the government must also socialize Islamic financial mechanism to SMEs as part of education efforts.

  16. Optimizing data access for wind farm control over hierarchical communication networks

    DEFF Research Database (Denmark)

    Madsen, Jacob Theilgaard; Findrik, Mislav; Madsen, Tatiana Kozlova

    2016-01-01

    delays and also by the choice of the time instances at which sensor information is accessed. In order to optimize the latter, we introduce an information quality metric and a mathematical model based on Markov chains, which are compared performance-wise to a heuristic approach for finding this parameter....... This information quality metric is called mismatch probability, mmPr, and is used to express quantitatively the information accuracy in a given scenario. Lastly measurements of different communication technologies have been performed in order to carry out the analysis in a practically relevant scenario...

  17. Dynamic spectrum access in wireless ad hoc networks: issues and possible solutions

    Science.gov (United States)

    Zhang, Zhensheng; Soni, Tarun

    2010-04-01

    In this paper, we present a brief overview on the recent development of the dynamical spectrum access (DSA) techniques, focusing on the following areas: characteristics of the available bandwidth of the primary users, sensing technologies and sensing intervals to detect white spaces, spectrum allocation and management, reliability of the secondary user, tradeoff between spectrum/performance gain versus additional overhead used in implementing DSA, and cross layer optimization in spectrum sharing. Some of tradeoff studies are presented in terms of price of anarchy, which is defined as the price that a decentralized system should pay for not being coordinated. We will also discuss some of the open issues in deploying DSA.

  18. 77 FR 47834 - Combined Notice of Filings

    Science.gov (United States)

    2012-08-10

    ..., LLC. Description: Big Sandy Fuel Filing effective 9-1-2012 to be effective 9/1/2012. Filed Date: 7/31... Negotiated Rate to be effective 8/ 1/2012. Filed Date: 7/31/12. Accession Number: 20120731-5120. Comments Due...: Compliance with CP12-5-000 to be effective 9/1/2012. Filed Date: 7/31/12. Accession Number: 20120731-5129...

  19. Cooperative Access Schemes for Efficient SWIPT Transmissions in Cognitive Radio Networks

    OpenAIRE

    Shafie, Ahmed El; Al-Dhahir, Naofal; Hamila, Ridha

    2016-01-01

    We investigate joint information and energy cooperative schemes in a slotted-time cognitive radio network with a primary transmitter-receiver pair and a set of secondary transmitter-receiver pairs. The primary transmitter is assumed to be an energy-harvesting node. We propose a three-stage cooperative transmission protocol. During the first stage, the primary user releases a portion of its time slot to the secondary nodes to send their data and to power the energy-harvesting primary transmitt...

  20. Study of converged 60 GHz radio over fiber with WDM-PON access networks

    OpenAIRE

    Shao, Tong

    2012-01-01

    Recently, convergence of 60 GHz radio over fiber (RoF) technique with wavelength division multiplexing (WDM) passive optical networks (PON) has raised great interests because it provides the possibility for simultaneous broadband 60 GHz signal generation and multi-gigabit per second wireline transmission. The objective of the thesis is to study the solutions for converged 60 GHz RoF and WDM-PON technique.In this thesis, we have made the following achievements for RoF technology and the integr...