Performance analysis of IMS based LTE and WIMAX integration architectures

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A. Bagubali

2016-12-01

Full Text Available In the current networking field many research works are going on regarding the integration of different wireless technologies, with the aim of providing uninterrupted connectivity to the user anywhere, with high data rates due to increased demand. However, the number of objects like smart devices, industrial machines, smart homes, connected by wireless interface is dramatically increasing due to the evolution of cloud computing and internet of things technology. This Paper begins with the challenges involved in such integrations and then explains the role of different couplings and different architectures. This paper also gives further improvement in the LTE and Wimax integration architectures to provide seamless vertical handover and flexible quality of service for supporting voice, video, multimedia services over IP network and mobility management with the help of IMS networks. Evaluation of various parameters like handover delay, cost of signalling, packet loss,, is done and the performance of the interworking architecture is analysed from the simulation results. Finally, it concludes that the cross layer scenario is better than the non cross layer scenario.

System-Level Model for OFDM WiMAX Transceiver in Radiation Environment

International Nuclear Information System (INIS)

Abdel Alim, O.; Elboghdadly, N.; Ashour, M.M.; Elaskary, A.M.

2008-01-01

WiMAX (Worldwide Inter operability for Microwave Access), an evolving standard for point-to-multipoint wireless networking, works for the l ast mile c onnections for replacing optical fiber technology network but with no need for adding more infra structure within crowded areas. Optical fiber technology is seriously considered for communication and monitoring applications in space and around nuclear reactors. Space and nuclear environments are characterized, in particular, by the presence of ionizing radiation fields. Therefore the influence of radiation on such networks needs to be investigated. This paper has the objective of building a System level model for a WiMAX OFDM (Orthogonal Frequency Division Multiplexing) based transceiver. Modeling irradiation noise as an external effect added to the Additive White Gaussian noise (AWGN). Then analyze, discuss the results based on qualitatively performance evaluation using BER calculations for radiation environment

Applying FDTD to the Coverage Prediction of WiMAX Femtocells

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Valcarce Alvaro

2009-01-01

Full Text Available Femtocells, or home base stations, are a potential future solution for operators to increase indoor coverage and reduce network cost. In a real WiMAX femtocell deployment in residential areas covered by WiMAX macrocells, interference is very likely to occur both in the streets and certain indoor regions. Propagation models that take into account both the outdoor and indoor channel characteristics are thus necessary for the purpose of WiMAX network planning in the presence of femtocells. In this paper, the finite-difference time-domain (FDTD method is adapted for the computation of radiowave propagation predictions at WiMAX frequencies. This model is particularly suitable for the study of hybrid indoor/outdoor scenarios and thus well adapted for the case of WiMAX femtocells in residential environments. Two optimization methods are proposed for the reduction of the FDTD simulation time: the reduction of the simulation frequency for problem simplification and a parallel graphics processing units (GPUs implementation. The calibration of the model is then thoroughly described. First, the calibration of the absorbing boundary condition, necessary for proper coverage predictions, is presented. Then a calibration of the material parameters that minimizes the error function between simulation and real measurements is proposed. Finally, some mobile WiMAX system-level simulations that make use of the presented propagation model are presented to illustrate the applicability of the model for the study of femto- to macrointerference.

High-resolution, low-delay, and error-resilient medical ultrasound video communication using H.264/AVC over mobile WiMAX networks.

Science.gov (United States)

Panayides, Andreas; Antoniou, Zinonas C; Mylonas, Yiannos; Pattichis, Marios S; Pitsillides, Andreas; Pattichis, Constantinos S

2013-05-01

In this study, we describe an effective video communication framework for the wireless transmission of H.264/AVC medical ultrasound video over mobile WiMAX networks. Medical ultrasound video is encoded using diagnostically-driven, error resilient encoding, where quantization levels are varied as a function of the diagnostic significance of each image region. We demonstrate how our proposed system allows for the transmission of high-resolution clinical video that is encoded at the clinical acquisition resolution and can then be decoded with low-delay. To validate performance, we perform OPNET simulations of mobile WiMAX Medium Access Control (MAC) and Physical (PHY) layers characteristics that include service prioritization classes, different modulation and coding schemes, fading channels conditions, and mobility. We encode the medical ultrasound videos at the 4CIF (704 × 576) resolution that can accommodate clinical acquisition that is typically performed at lower resolutions. Video quality assessment is based on both clinical (subjective) and objective evaluations.

Downlink Coexistence Performance Assessment and Techniques for WiMAX Services from High Altitude Platform and Terrestrial Deployments

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Grace D

2008-01-01

Full Text Available Abstract We investigate the performance and coexistence techniques for worldwide interoperability for microwave access (WiMAX delivered from high altitude platforms (HAPs and terrestrial systems in shared 3.5 GHz frequency bands. The paper shows that it is possible to provide WiMAX services from individual HAP systems. The coexistence performance is evaluated by appropriate choice of parameters, which include the HAP deployment spacing radius, directive antenna beamwidths based on adopted antenna models for HAPs and receivers. Illustrations and comparisons of coexistence techniques, for example, varying the antenna pointing offset, transmitting and receiving antenna beamwidth, demonstrate efficient ways to enhance the HAP system performance while effectively coexisting with terrestrial WiMAX systems.

Sending Safety Video over WiMAX in Vehicle Communications

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Jun Steed Huang

2013-10-01

Full Text Available This paper reports on the design of an OPNET simulation platform to test the performance of sending real-time safety video over VANET (Vehicular Adhoc NETwork using the WiMAX technology. To provide a more realistic environment for streaming real-time video, a video model was created based on the study of video traffic traces captured from a realistic vehicular camera, and different design considerations were taken into account. A practical controller over real-time streaming protocol is implemented to control data traffic congestion for future road safety development. Our driving video model was then integrated with the WiMAX OPNET model along with a mobility model based on real road maps. Using this simulation platform, different mobility cases have been studied and the performance evaluated in terms of end-to-end delay, jitter and visual experience.

Downlink Coexistence Performance Assessment and Techniques for WiMAX Services from High Altitude Platform and Terrestrial Deployments

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D. Grace

2008-11-01

Full Text Available We investigate the performance and coexistence techniques for worldwide interoperability for microwave access (WiMAX delivered from high altitude platforms (HAPs and terrestrial systems in shared 3.5 GHz frequency bands. The paper shows that it is possible to provide WiMAX services from individual HAP systems. The coexistence performance is evaluated by appropriate choice of parameters, which include the HAP deployment spacing radius, directive antenna beamwidths based on adopted antenna models for HAPs and receivers. Illustrations and comparisons of coexistence techniques, for example, varying the antenna pointing offset, transmitting and receiving antenna beamwidth, demonstrate efficient ways to enhance the HAP system performance while effectively coexisting with terrestrial WiMAX systems.

Deficit Round Robin with Fragmentation Scheduling to Achieve Generalized Weighted Fairness for Resource Allocation in IEEE 802.16e Mobile WiMAX Networks

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Chakchai So-In

2010-10-01

Full Text Available Deficit Round Robin (DRR is a fair packet-based scheduling discipline commonly used in wired networks where link capacities do not change with time. However, in wireless networks, especially wireless broadband networks, i.e., IEEE 802.16e Mobile WiMAX, there are two main considerations violate the packet-based service concept for DRR. First, the resources are allocated per Mobile WiMAX frame. To achieve full frame utilization, Mobile WiMAX allows packets to be fragmented. Second, due to a high variation in wireless channel conditions, the link/channel capacity can change over time and location. Therefore, we introduce a Deficit Round Robin with Fragmentation (DRRF to allocate resources per Mobile WiMAX frame in a fair manner by allowing for varying link capacity and for transmitting fragmented packets. Similar to DRR and Generalized Processor Sharing (GPS, DRRF achieves perfect fairness. DRRF results in a higher throughput than DRR (80% improvement while causing less overhead than GPS (8 times less than GPS. In addition, in Mobile WiMAX, the quality of service (QoS offered by service providers is associated with the price paid. This is similar to a cellular phone system; the users may be required to pay air-time charges. Hence, we have also formalized a Generalized Weighted Fairness (GWF criterion which equalizes a weighted sum of service time units or slots, called temporal fairness, and transmitted bytes, called throughput fairness, for customers who are located in a poor channel condition or at a further distance versus for those who are near the base stations, or have a good channel condition. We use DRRF to demonstrate the application of GWF. These fairness criteria are used to satisfy basic requirements for resource allocation, especially for non real-time traffic. Therefore, we also extend DRRF to support other QoS requirements, such as minimum reserved traffic rate, maximum sustained traffic rate, and traffic priority. For real

Wifi, WiMax and LTE multi-hop mesh networks basic communication protocols and application areas

CERN Document Server

Wei, Hung-Yu; Dixit, Sudhir

2013-01-01

Wifi, WiMAX, and Cellular Multihop Networks presents an overview of WiFi-based and WiMAX-based multihop relay networks. As the first text to cover IEEE 802.16j multihop hop relay technology, this revolutionary resource explores the latest advances in multi-hop and ad-hoc networking. Not only does this reference provide the technological aspects, but also the applications for the emerging technology and architectural issues. Ranging from introductory material to advanced topics, this guidebook, plus PowerPoint slides, is essential for engineers, researchers, and students interested in

Capacity Evaluation for IEEE 802.16e Mobile WiMAX

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Chakchai So-In

2010-01-01

Full Text Available We present a simple analytical method for capacity evaluation of IEEE 802.16e Mobile WiMAX networks. Various overheads that impact the capacity are explained and methods to reduce these overheads are also presented. The advantage of a simple model is that the effect of each decision and sensitivity to various parameters can be seen easily. We illustrate the model by estimating the capacity for three sample applications—Mobile TV, VoIP, and data. The analysis process helps explain various features of IEEE 802.16e Mobile WiMAX. It is shown that proper use of overhead reducing mechanisms and proper scheduling can make an order of magnitude difference in performance. This capacity evaluation method can also be used for validation of simulation models.

Analisis Kinerja Subscriber Station WiMAX di Urban Area Bandung

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DWI ARYANTA

2017-06-01

Full Text Available ABSTRAK   Teknologi komunikasi wireless semakin pesat mengalami perkembangan. WiMAX  merupakan suatu teknologi broadband yang didukung oleh standar IEEE 802.16d (802.16-2004 yang mampu memberikan layanan data berkecepatan tinggi hingga 75 Mbps dalam radius maksimal 40-50 km pada bandwidth 20 MHz. Alokasi frekuensi yang dipakai Indonesia untuk jaringan WiMAX  ini ialah 3,3 – 3,4 GHz. Penelitian ini dilakukan dengan melakukan proses pengukuran kinerja perangkat radio WiMAX  yaitu HiMax 331-SS. Proses pengukuran dilakukan antara CPE dan base station dengan antenna sektoral 1200 pada ketinggian 45 m. Lokasi pengukuran dilakukan di beberapa area kota Bandung yang telah ditentukan sebelumnya. Hasil pengukuran memperlihatkan nilai CINR tertinggi adalah 31 dB dengan modulasi 64 QAM – ¾ dan terendah nilai 10 dB dengan modulasi BPSK 1/2. Nilai RSSI tertinggi -54 dBm berada dan nilai RSSI terendah -89 dBm. Nilai throughput tertinggi untuk layanan streaming video sebesar  1000,8 kbps (downlink dengan modulasi 64 QAM – ¾. Nilai delay terendah sebesar 56,247 ms pada kondisi LOS dan tertinggi sebesar 139,5 ms pada kondisi NLOS. Nilai terbesar packet loss sebesar 20% yaitu pada lokasi pengukuran terjauh 14,3 km. Kata Kunci : delay, packet loss, RSSI, CINR, throughput, CPE, WiMAX .   ABSTRACT   Wireless communication technologies have evolved more rapidly. WiMAX  is a broadband technology that is supported by the IEEE standard 802.16-2004/d which is able to provide high speed data services of up to 75 Mbps within a radius of 40-50 km at a maximum bandwidth of 20 MHz. Indonesia frequency allocation used for the WiMAX  network is 3.3 to 3.4 GHz. This study was conducted with the performance measurement process that is Himax 331 WiMAX  radio - SS. Process measurement is made between the CPE and base station sector antennas at a height of 45 m in 1200. Locations measurements performed in several areas of Bandung predetermined. The measurement

RLAM: A Dynamic and Efficient Reinforcement Learning-Based Adaptive Mapping Scheme in Mobile WiMAX Networks

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M. Louta

2014-01-01

Full Text Available WiMAX (Worldwide Interoperability for Microwave Access constitutes a candidate networking technology towards the 4G vision realization. By adopting the Orthogonal Frequency Division Multiple Access (OFDMA technique, the latest IEEE 802.16x amendments manage to provide QoS-aware access services with full mobility support. A number of interesting scheduling and mapping schemes have been proposed in research literature. However, they neglect a considerable asset of the OFDMA-based wireless systems: the dynamic adjustment of the downlink-to-uplink width ratio. In order to fully exploit the supported mobile WiMAX features, we design, develop, and evaluate a rigorous adaptive model, which inherits its main aspects from the reinforcement learning field. The model proposed endeavours to efficiently determine the downlink-to-uplinkwidth ratio, on a frame-by-frame basis, taking into account both the downlink and uplink traffic in the Base Station (BS. Extensive evaluation results indicate that the model proposed succeeds in providing quite accurate estimations, keeping the average error rate below 15% with respect to the optimal sub-frame configurations. Additionally, it presents improved performance compared to other learning methods (e.g., learning automata and notable improvements compared to static schemes that maintain a fixed predefined ratio in terms of service ratio and resource utilization.

Investigation of a new handover approach in LTE and WiMAX.

Science.gov (United States)

Hindia, Mohammad Nour; Reza, Ahmed Wasif; Noordin, Kamarul Ariffin

2014-01-01

Nowadays, one of the most important challenges in heterogeneous networks is the connection consistency between the mobile station and the base stations. Furthermore, along the roaming process between the mobile station and the base station, the system performance degrades significantly due to the interferences from neighboring base stations, handovers to inaccurate base station and inappropriate technology selection. In this paper, several algorithms are proposed to improve mobile station performance and seamless mobility across the long-term evolution (LTE) and Worldwide Interoperability for Microwave Access (WiMAX) technologies, along with a minimum number of redundant handovers. Firstly, the enhanced global positioning system (GPS) and the novel received signal strength (RSS) prediction approaches are suggested to predict the target base station accurately. Then, the multiple criteria with two thresholds algorithm is proposed to prioritize the selection between LTE and WiMAX as the target technology. In addition, this study also covers the intercell and cochannel interference reduction by adjusting the frequency reuse ratio 3 (FRR3) to work with LTE and WiMAX. The obtained results demonstrate high next base station prediction efficiency and high accuracy for both horizontal and vertical handovers. Moreover, the received signal strength is kept at levels higher than the threshold, while maintaining low connection cost and delay within acceptable levels. In order to highlight the combination of the proposed algorithms' performance, it is compared with the existing RSS and multiple criteria handover decision algorithms.

Fair Adaptive Bandwidth and Subchannel Allocation in the WiMAX Uplink

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Antoni Morell

2009-01-01

Full Text Available In some modern communication systems, as it is the case of WiMAX, it has been decided to implement Demand Assignment Multiple Access (DAMA solutions. End-users request transmission opportunities before accessing the system, which provides an efficient way to share system resources. In this paper, we briefly review the PHY and MAC layers of an OFDMA-based WiMAX system, and we propose to use a Network Utility Maximization (NUM framework to formulate the DAMA strategy foreseen in the uplink of IEEE 802.16. Utility functions are chosen to achieve fair solutions attaining different degrees of fairness and to further support the QoS requirements of the services in the system. Moreover, since the standard allocates resources in a terminal basis but each terminal may support several services, we develop a new decomposition technique, the coupled-decompositions method, that obtains the optimal service flow allocation with a small number of iterations (the improvement is significant when compared to other known solutions. Furthermore, since the PHY layer in mobile WiMAX has the means to adapt the transport capacities of the links between the Base Station (BS and the Subscriber Stations (SSs, the proposed PHY-MAC cross-layer design uses this extra degree of freedom in order to enhance the network utility.

Zero-forcing pre-coding for MIMO WiMAX transceivers: Performance analysis and implementation issues

Science.gov (United States)

Cattoni, A. F.; Le Moullec, Y.; Sacchi, C.

Next generation wireless communication networks are expected to achieve ever increasing data rates. Multi-User Multiple-Input-Multiple-Output (MU-MIMO) is a key technique to obtain the expected performance, because such a technique combines the high capacity achievable using MIMO channel with the benefits of space division multiple access. In MU-MIMO systems, the base stations transmit signals to two or more users over the same channel, for this reason every user can experience inter-user interference. This paper provides a capacity analysis of an online, interference-based pre-coding algorithm able to mitigate the multi-user interference of the MU-MIMO systems in the context of a realistic WiMAX application scenario. Simulation results show that pre-coding can significantly increase the channel capacity. Furthermore, the paper presents several feasibility considerations for implementation of the analyzed technique in a possible FPGA-based software defined radio.

Resource management framework for QoS scheduling in IEEE 802.16 WiMAX networks

DEFF Research Database (Denmark)

Wang, Hua; Dittmann, Lars

2009-01-01

IEEE 802.16, also known as WiMAX, has received much attention recently for its capability to support multiple types of applications with diverse Quality-of-Service (QoS) requirements. Beyond what the standard has defined, radio resource management (RRM) still remains an open issue, which plays...... an important role in QoS provisioning for different types of services. In this chapter, we propose a downlink resource management framework for QoS scheduling in OFDMA based WiMAX systems. Our framework consists of a dynamic resource allocation (DRA) module and a connection admission control (CAC) module...

Downlink resource management for QoS scheduling in IEEE 802.16 WiMAX networks

DEFF Research Database (Denmark)

Wang, Hua; Dittmann, Lars

2010-01-01

IEEE 802.16, also known as WiMAX, has received much attention recently for its capability to support multiple types of applications with diverse Quality-of-Service (QoS) requirements. Beyond what the standard has defined, radio resource management (RRM) still remains an open issue, which plays...... an important role in QoS provisioning for different types of services. In this paper, we propose a downlink resource management framework for QoS scheduling in OFDMA based WiMAX systems. Our framework consists of a dynamic resource allocation (DRA) module and a connection admission control (CAC) module. A two...

A smart city application: a fully controlled street lighting isle based on Raspberry-Pi card, a ZigBee sensor network and WiMAX.

Science.gov (United States)

Leccese, Fabio; Cagnetti, Marco; Trinca, Daniele

2014-12-18

A smart city application has been realized and tested. It is a fully remote controlled isle of lamp posts based on new technologies. It has been designed and organized in different hierarchical layers, which perform local activities to physically control the lamp posts and transmit information with another for remote control. Locally, each lamp post uses an electronic card for management and a ZigBee tlc network transmits data to a central control unit, which manages the whole isle. The central unit is realized with a Raspberry-Pi control card due to its good computing performance at very low price. Finally, a WiMAX connection was tested and used to remotely control the smart grid, thus overcoming the distance limitations of commercial Wi-Fi networks. The isle has been realized and tested for some months in the field.

A Smart City Application: A Fully Controlled Street Lighting Isle Based on Raspberry-Pi Card, a ZigBee Sensor Network and WiMAX

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Fabio Leccese

2014-12-01

Full Text Available A smart city application has been realized and tested. It is a fully remote controlled isle of lamp posts based on new technologies. It has been designed and organized in different hierarchical layers, which perform local activities to physically control the lamp posts and transmit information with another for remote control. Locally, each lamp post uses an electronic card for management and a ZigBee tlc network transmits data to a central control unit, which manages the whole isle. The central unit is realized with a Raspberry-Pi control card due to its good computing performance at very low price. Finally, a WiMAX connection was tested and used to remotely control the smart grid, thus overcoming the distance limitations of commercial Wi-Fi networks. The isle has been realized and tested for some months in the field.

Comparative Analysis between WiMAX and Fiber Optics Backhaul Network Deployment in Developing Countries - The Case of Ghana

DEFF Research Database (Denmark)

Adjin, Daniel Michael Okwabi; Williams, Idongesit

to deploy than mobile technologies. But in many developing countries, there is preference for the deployment of fiber optics rather than a broadband wireless solution for the deployment of broadband internet. Argument is made in this paper using the Expectation Confirmation Theory to reveal the level...... of satisfaction of mobile WiMAX compared to what Fiber optics would bring to rural areas in terms of broadband provisioning, Cost of access, Cost of deployment, Network accessibility and availability. The case of investigation is Northern Ghana due to the proliferation of rural areas in that region...

Analyzing mobile WiMAX base station deployment under different frequency planning strategies

Science.gov (United States)

Salman, M. K.; Ahmad, R. B.; Ali, Ziad G.; Aldhaibani, Jaafar A.; Fayadh, Rashid A.

2015-05-01

The frequency spectrum is a precious resource and scarce in the communication markets. Therefore, different techniques are adopted to utilize the available spectrum in deploying WiMAX base stations (BS) in cellular networks. In this paper several types of frequency planning techniques are illustrated, and a comprehensive comparative study between conventional frequency reuse of 1 (FR of 1) and fractional frequency reuse (FFR) is presented. These techniques are widely used in network deployment, because they employ universal frequency (using all the available bandwidth) in their base station installation/configuration within network system. This paper presents a network model of 19 base stations in order to be employed in the comparison of the aforesaid frequency planning techniques. Users are randomly distributed within base stations, users' resource mapping and their burst profile selection are based on the measured signal to interference plus-noise ratio (SINR). Simulation results reveal that the FFR has advantages over the conventional FR of 1 in various metrics. 98 % of downlink resources (slots) are exploited when FFR is applied, whilst it is 81 % at FR of 1. Data rate of FFR has been increased to 10.6 Mbps, while it is 7.98 Mbps at FR of 1. The spectral efficiency is better enhanced (1.072 bps/Hz) at FR of 1 than FFR (0.808 bps/Hz), since FR of 1 exploits all the Bandwidth. The subcarrier efficiency shows how many data bits that can be carried by subcarriers under different frequency planning techniques, the system can carry more data bits under FFR (2.40 bit/subcarrier) than FR of 1 (1.998 bit/subcarrier). This study confirms that FFR can perform better than conventional frequency planning (FR of 1) which made it a strong candidate for WiMAX BS deployment in cellular networks.

Optimizing WiMAX: Mitigating Co-Channel Interference for Maximum Spectral Efficiency

International Nuclear Information System (INIS)

Ansari, A.Q.; Memon, A.L.; Qureshi, I.A.

2016-01-01

The efficient use of radio spectrum is one of the most important issues in wireless networks because spectrum is generally limited and wireless environment is constrained to channel interference. To cope up and for increased usefulness of radio spectrum wireless networks use frequency reuse technique. The frequency reuse technique allows the use of same frequency band in different cells of same network considering inter-cell distance and resulting interference level. WiMAX (Worldwide Interoperability for Microwave Access) PHY profile is designed to use FRF (Frequency Reuse Factor) of one. When FRF of one is used it results in an improved spectral efficacy but also results in CCI (Co-Channel interference) at cell boundaries. The effect of interference is always required to be measured so that some averaging/ minimization techniques may be incorporated to keep the interference level up to some acceptable threshold in wireless environment. In this paper, we have analyzed, that how effectively CCI impact can be mitigated by using different subcarrier permutation types presented in IEEE 802.16 standard. A simulation based analysis is presented wherein impact of using same and different permutation base in adjacent cells in a WiMAX network on CCI, under varying load conditions is analyzed. We have further studied the effect of permutation base in environment where frequency reuse technique is used in conjunction with cell sectoring for better utilization of radio spectrum. (author)

Studi Perancangan Jaringan Worldwide Interoperability For Microwave Access (Wimax Di Area Banyumas

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Alfin Hikmaturokhman

2012-05-01

Full Text Available At present the need for higher internet connection along with the age which is growing so fast. Then there is the latest breakthrough in telecomunications that is WiMAX technology is a wireless broadband technology reffered the IEEE 802.16 standard. WiMAX technology comes with a network of excellence in aspects of data access speed, wide area coverage and the presence of QoS is can allocate frequencies in accordance with user needs using OFDM technology. WiMAX technology can reach area far as 50 kilometers, also allows user equipment (customer premise equipment or CPE to get a broadband connection without having a direct path (non line of sight, NLOS to the base station (BS and provides a total data rate of up to 75 Mbps. Results of this Final project assumed that the area where will be design is Banyumas district. Then final project results of the PRX -100.31 dB; the Total Margin of 23.56 dB; Path los of 134.5 dB; gamma (? of 4.375; Frequency correction factor (?PLf of 0,36; antenna correction factor (?PLh is -3,25; Radius Cells (d is approximately 1995 meters; area of cell is at 10,34010495 km2 and the number of cells 133

WiMAX security and quality of service an end-to-end perspective

CERN Document Server

Tang, Seok-Yee; Sharif, Hamid

2010-01-01

WiMAX is the first standard technology to deliver true broadband mobility at speeds that enable powerful multimedia applications such as Voice over Internet Protocol (VoIP), online gaming, mobile TV, and personalized infotainment. WiMAX Security and Quality of Service, focuses on the interdisciplinary subject of advanced Security and Quality of Service (QoS) in WiMAX wireless telecommunication systems including its models, standards, implementations, and applications. Split into 4 parts, Part A of the book is an end-to-end overview of the WiMAX architecture, protocol, and system requirements.

WiMAX OFDM system simulation and sub-system FPGA implementation

International Nuclear Information System (INIS)

Elaskary, A.M.F.

2009-01-01

Orthogonal frequency division multiplexing (OFDM) has been used in many wireless communication systems also it is gaining a lot of attention for the next generations of mobile communication systems. OFDM is considered a good candidate for wireless systems because it has high bandwidth efficiency and can transmit at very high data rate in multi path, interference , and fading environment. in general OFDM has widely been studied and implemented to combat transmission channel impairments, but some challenges still facing OFDM in transmission system implementation especially for recent and future applications. One of these important applications is the worldwide interoperability for microwave access (WiMAX) system. According to the IEEE 802.16 standards, WiMAX is considered as a good solution for last mile connection at crowded areas and a high-speed internet connection to mobile vehicles with speed of up to 300 km/h. This thesis studies OFDM system in details and proposes simulink models for simulating OFDM impairments and its effects on system performance. This study has been used for building up system level and end to end WiMAX OFDM transmitter/receiver which follows published specifications in IEEE 802.16 standards using mat lab/simulink.

Rectangular Ring Antenna Excited by Circular Disc Monopole for WiMAX System

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Souphanna Vongsack

2014-01-01

Full Text Available This research presents a rectangular ring antenna excited by a circular disc monopole (CDM mounted in front of a square reflector. The proposed antenna is designed to cover a frequency range of 2.300–5.825 GHz and thereby is suitable for WiMAX applications. Multiple parametric studies were carried out using the CST Microwave Studio simulation program. A prototype antenna was fabricated and experimented. The measurements were taken and compared with the simulation results, which indicates good agreement between both results. The prototype antenna produces an impedance bandwidth (|S11| < −10 dB that covers the WiMAX frequency range and a constant unidirectional radiation pattern (θ=0° and ∅=90°. The minimum and maximum gains are 3.7 and 8.7 dBi, respectively. The proposed antenna is of compact size and has good unidirectional radiation performance. Thus, it is very suitable for a multitude of WiMAX applications.

Design and Development of Basic Physical Layer WiMAX Network Simulation Models

Science.gov (United States)

2009-01-01

Wide Web . The third software version was developed during the period of 22 August to 4 November, 2008. The software version developed during the...researched on the Web . The mathematics of some fundamental concepts such as Fourier transforms, convolutional coding techniques were also reviewed...Mathworks Matlab users’ website. A simulation model was found, entitled Estudio y Simulacion de la capa Jisica de la norma 802.16 ( Sistema WiMAX) developed

Evaluasi Kinerja Layanan IPTV pada Jaringan Testbed WiMAX Berbasis Standar IEEE 802.16-2004

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Prasetiyono Hari Mukti

2015-09-01

Full Text Available In this paper, a performance evaluation for IPTV Services over WiMAX testbed based on IEEE Standard 802.16-2004 will be described. The performance of the proposed system is evaluated in terms of delay, jitter, throughput and packet loss. Service performance evaluations are conducted on network topology of point-to-point in the variation of background traffic with different scheduling types. Background traffic is injected into the system to give the sense that the proposed system has variation traffic load. Scheduling type which are used in this paper are Best Effort (BE, Non-Real-Time Polling Service (nrtPS, Real-Time Polling Service (rtPS and Unsolicited Grant Service (UGS. The expemerintal results of IPTV service performance over the testbed network show that the maximum average of delay, jitter, packet loss and jitter are 16.581 ms, 58.515 ms, 0.67 Mbps dan 10.96%, respectively.

Analisis Unjuk Kerja Horizontal Handover Mobile Wimax Mendukung Layanan Mobile TV

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Ammatia Risty

2016-05-01

Full Text Available IEEE 802.16e-2005 teknologi mobile WiMAX merupakan salah satu alternatif yang dapat memberikan datarate 15 Mbps yang lebih baik daripada teknologi 3G, WLAN, dan lain-lain. Mobile WiMAX juga memberikan cakupan area yang luas. Oleh karena itu, WiMAX mampu memberikan layanan berbagai macam aplikasi multimedia seperti VoIP, IPTV, Video conferencing. dan aplikasi real-time lainnya. Selain itu, Mobile WiMAX juga mendukung mobility secara portable, mobile, dan nomadic. Saat ini IPTV muncul pada mobile phone, yang dinamakan mobile TV dimana layanan IPTV akan dapat diakses dalam keadaan bergerak. Hal itu membutuhkan suatu teknologi yang mendukung mobility namun tetap dapat menerima layanan IPTV dengan baik. Teknologi mobile WiMAX adalah teknologi yang cocok untuk mendukung layanan IPTV khususnya untuk user yang sedang bergerak. Akibat dari user yang bergerak maka memungkinkan user tersebut melakukan handover. Penelitian ini menganalisis parameter unjuk kerja yang mempengaruhi pada mobile TV saat user melakukan  handover  pada jaringan mobile WiMAX seperti jitter, end to end delay, throughput, handover delay dengan skenario perbedaan kecepatan dan perubahan jumlah user dalam satu cakupan area. Berdasarkan hasil simulasi untuk skenario perbedaan kecepatan (maksimum 100 km/jam diperoleh nilai end to end delay sebesar 23.234 ms, jitter sebesar 0.047 ms, throughput sebesar 637.723 Kbps. Sedangkan skenario jumlah user diperoleh nilai end to end delay 27.218 ms, jitter sebesar 0.057 ms, throughput sebesar 558.881 Kbps. Hasil dari kedua skenario menunjukkan bahwa saat kecepatan dan jumlah user naik maka parameter kualitas layanan turun namun masih memenuhi syarat kualitas layanan Mobile TV (IPTV.

Experimental evaluation of high speed impulse radio UWB interference on WiMAX narrowband systems

DEFF Research Database (Denmark)

Yu, Xianbin; Yin, Xiaoli; Tafur Monroy, Idelfonso

2010-01-01

Interference of high speed impulse radio ultrawideband (IR-UWB) on 5.735GHz single carrier 64/256-QAM WiMAX narrowband signals is experimentally investigated. The experimental results indicate that the coexistence of 625Mbps and 2Gbps IR-UWB signals causes penalties of 3dB and 0.5dB respectively...... to the WiMAX channel. At higher bit rates, IR-UWB technology is therefore expected to reduce its interference on WiMAX signals. This work serves as further motivation for the exploration of IR-UWB systems with higher speed and higher capacity....

A Rectangular Ring, Open-Ended Monopole Antenna with Two Symmetric Strips for WLAN and WiMAX Applications

Directory of Open Access Journals (Sweden)

Joong-Han Yoon

2013-01-01

Full Text Available A triple-band rectangular ring, open-ended monopole antenna with symmetric L strips for wireless local area network (WLAN/Worldwide Interoperability of Microwave Access (WiMAX applications is proposed. The proposed antenna consists of two symmetric folded arms and L strips. Based on the concept, a prototype of the proposed triple antenna has been designed, fabricated, and tested. The numerical and experimental results demonstrated that the proposed antenna satisfied the −10 dB impedance bandwidth requirement while simultaneously covering the WLAN and WiMAX bands. Furthermore, this paper presented and discussed the 2D radiation patterns and 3D gains according to the results of the experiment. The proposed antenna’s peak gain varied between 2.17 and 4.93 dBi, and its average gain varied between −2.97 and −0.53 dBi.

WIRELESS FIDELITY (Wi-Fi) BROADBAND NETWORK ...

African Journals Online (AJOL)

ES Obe

broadband speed and coverage, while Wi-Fi can be integrated with WiMAX networks to provide Internet ... Microwave Access (WiMAX), IEEE 802.11 standards. 1.0 INTRODUCTION .... These 2G systems provided circuit- switched data ...

Pemodelan dan Verifikasi Formal Pengaruh Mobility pattern Terhadap Handoff Latency pada Jaringan WiMAX

Directory of Open Access Journals (Sweden)

I Nym Saputra Wahyu Wijaya

2016-01-01

Full Text Available In order to decrease handoff latency and increase the successful of HHO conventional scheme, a development of handover scheme is done in standard protocol WiMAX IEEE 802.16e by adding mobility pattern. The superiority of handover scheme with mobility pattern can reduce handoff latency up to 50%, mean while the weakness of this scheme is a wrong act in determining target base station are often happen. Simulation can not showing the cause of that error. So, we do formal verification in to hard handover model with mobility pattern.             In this research, behaviour system is modeled with continuous-time Markov chain (CTMC. The model is foccused to aproximating the influence of mobility pattern in to handoff latency from WiMAX hard handover mechanism. In order to set up a series markov chain models handover system can follow steps, such as: represents the state space, give a number in all transitions, generate the rate transition matrix (infinitesimal generator.             Probabilistic model checking in the research are using quantitative properties and qualitative properties. Formal verification concerning properties has relation with handover in WiMAX network showing that 70% from mobile station which doing scanning with mobility pattern are success doing handover. 24% of them doing scanning conventional as a result of wrongness in act determining target base station, so handoff latency which is pictured will bigger than a system that is only use conventional scanning method.

Emerging wireless networks concepts, techniques and applications

CERN Document Server

Makaya, Christian

2011-01-01

An authoritative collection of research papers and surveys, Emerging Wireless Networks: Concepts, Techniques, and Applications explores recent developments in next-generation wireless networks (NGWNs) and mobile broadband networks technologies, including 4G (LTE, WiMAX), 3G (UMTS, HSPA), WiFi, mobile ad hoc networks, mesh networks, and wireless sensor networks. Focusing on improving the performance of wireless networks and provisioning better quality of service and quality of experience for users, it reports on the standards of different emerging wireless networks, applications, and service fr

Minimum decoding trellis length and truncation depth of wrap-around Viterbi algorithm for TBCC in mobile WiMAX

Directory of Open Access Journals (Sweden)

Liu Yu-Sun

2011-01-01

Full Text Available Abstract The performance of the wrap-around Viterbi decoding algorithm with finite truncation depth and fixed decoding trellis length is investigated for tail-biting convolutional codes in the mobile WiMAX standard. Upper bounds on the error probabilities induced by finite truncation depth and the uncertainty of the initial state are derived for the AWGN channel. The truncation depth and the decoding trellis length that yield negligible performance loss are obtained for all transmission rates over the Rayleigh channel using computer simulations. The results show that the circular decoding algorithm with an appropriately chosen truncation depth and a decoding trellis just a fraction longer than the original received code words can achieve almost the same performance as the optimal maximum likelihood decoding algorithm in mobile WiMAX. A rule of thumb for the values of the truncation depth and the trellis tail length is also proposed.

UMA/GAN network architecture analysis

Science.gov (United States)

Yang, Liang; Li, Wensheng; Deng, Chunjian; Lv, Yi

2009-07-01

This paper is to critically analyze the architecture of UMA which is one of Fix Mobile Convergence (FMC) solutions, and also included by the third generation partnership project(3GPP). In UMA/GAN network architecture, UMA Network Controller (UNC) is the key equipment which connects with cellular core network and mobile station (MS). UMA network could be easily integrated into the existing cellular networks without influencing mobile core network, and could provides high-quality mobile services with preferentially priced indoor voice and data usage. This helps to improve subscriber's experience. On the other hand, UMA/GAN architecture helps to integrate other radio technique into cellular network which includes WiFi, Bluetooth, and WiMax and so on. This offers the traditional mobile operators an opportunity to integrate WiMax technique into cellular network. In the end of this article, we also give an analysis of potential influence on the cellular core networks ,which is pulled by UMA network.

Dynamic subframe allocation for mobile broadband m-health using IEEE 802.16j mobile multihop relay networks.

Science.gov (United States)

Alinejad, Ali; Istepanian, R S H; Philip, N

2012-01-01

The concept of 4G health will be one of the key focus areas of future m-health research and enterprise activities in the coming years. WiMAX technology is one of the constituent 4G wireless technologies that provides broadband wireless access (BWA). Despite the fact that WiMAX is able to provide a high data rate in a relatively large coverage; this technology has specific limitations such as: coverage, signal attenuation problems due to shadowing or path loss, and limited available spectrum. The IEEE 802.16j mobile multihop relay (MMR) technology is a pragmatic solution designed to overcome these limitations. The aim of IEEE 802.16j MMR is to expand the IEEE 802.16e's capabilities with multihop features. In particular, the uplink (UL) and downlink (DL) subframe allocation in WiMAX network is usually fixed. However, dynamic frame allocation is a useful mechanism to optimize uplink and downlink subframe size dynamically based on the traffic conditions through real-time traffic monitoring. This particular mechanism is important for future WiMAX based m-health applications as it allows the tradeoff in both UL and DL channels. In this paper, we address the dynamic frame allocation issue in IEEE 802.16j MMR network for m-health applications. A comparative performance analysis of the proposed approach is validated using the OPNET Modeler(®). The simulation results have shown an improved performance of resource allocation and end-to-end delay performance for typical medical video streaming application.

On-the-field performance of quintuple-play long-reach OFDM-based WDM-PON optical access networks.

Science.gov (United States)

Llorente, Roberto; Morant, Maria; Pellicer, Eloy; Herman, Milan; Nagy, Zsolt; Alves, Tiago; Cartaxo, Adolfo; Herrera, Javier; Correcher, Jose; Quinlan, Terence; Walker, Stuart; Rodrigues, Cláudio; Cluzeaud, Pierre; Schmidt, Axel; Piesiewicz, Radoslaw; Sambaraju, Rakesh

2014-03-24

In this paper the on-the-field performance of a WDM-PON optical access providing quintuple-play services using orthogonal frequency division multiplexing (OFDM) modulation is evaluated in a real fiber-to-the-home (FTTH) network deployed by Towercom operator in Bratislava (Slovakia). A bundle of quintuple-play services comprising full-standard OFDM-based signals (LTE, WiMAX, UWB and DVB-T) and an ad-hoc OFDM-GbE signal is transmitted in coexistence per single user. Both downstream and upstream transmission performances are evaluated in different on-the-field long-reach optical link distance configurations. Four wavelength multi-user transmission of quintuple-play OFDM services is demonstrated exceeding 60.8 km reach in standard single mode fiber.

Flexible Macroblock Ordering for Context-Aware Ultrasound Video Transmission over Mobile WiMAX

Science.gov (United States)

Martini, Maria G.; Hewage, Chaminda T. E. R.

2010-01-01

The most recent network technologies are enabling a variety of new applications, thanks to the provision of increased bandwidth and better management of Quality of Service. Nevertheless, telemedical services involving multimedia data are still lagging behind, due to the concern of the end users, that is, clinicians and also patients, about the low quality provided. Indeed, emerging network technologies should be appropriately exploited by designing the transmission strategy focusing on quality provision for end users. Stemming from this principle, we propose here a context-aware transmission strategy for medical video transmission over WiMAX systems. Context, in terms of regions of interest (ROI) in a specific session, is taken into account for the identification of multiple regions of interest, and compression/transmission strategies are tailored to such context information. We present a methodology based on H.264 medical video compression and Flexible Macroblock Ordering (FMO) for ROI identification. Two different unequal error protection methodologies, providing higher protection to the most diagnostically relevant data, are presented. PMID:20827292

Developing an active emergency medical service system based on WiMAX technology.

Science.gov (United States)

Li, Shing-Han; Cheng, Kai-An; Lu, Wen-Hui; Lin, Te-Chang

2012-10-01

The population structure has changed with the aging of population. In the present, elders account for 10.63% of the domestic population and the percentage is still gradually climbing. In other words, the demand for emergency services among elders in home environment is expected to grow in the future. In order to improve the efficiency and quality of emergency care, information technology should be effectively utilized to integrate medical systems and facilities, strengthen human-centered operation designs, and maximize the overall performance. The improvement in the quality and survival rate of emergency care is an important basis for better life and health of all people. Through integrated application of medical information systems and information communication technology, this study proposes a WiMAX-based emergency care system addressing the public demands for convenience, speed, safety, and human-centered operation of emergency care. This system consists of a healthcare service center, emergency medical service hospitals, and emergency ambulances. Using the wireless transmission capability of WiMAX, patients' physiological data can be transmitted from medical measurement facilities to the emergency room and emergency room doctors can provide immediate online instructions on emergency treatment via video and audio transmission. WiMAX technology enables the establishment of active emergency medical services.

Cross-Layer Design of the Inter-RAT Handover between UMTS and WiMAX

Directory of Open Access Journals (Sweden)

Bertin Philippe

2010-01-01

Full Text Available In future mobile networks, different radio access technologies will have to coexist. IEEE 802.21 MIH (Media-Independent Handover provides primitive mechanisms that ease the implementation of a seamless vertical handover (inter-RAT handover between different radio access technologies. However, it does not specify any handover execution mechanism. The first objective of this paper is to propose a novel MIHF (Media-Independent Handover Function variant, which is renamed interworking (IW sublayer. IW sublayer provides a seamless inter-RAT handover procedure between UMTS and WiMAX systems. It relies on a new intersystem retransmission mechanism with cross-layer interaction ability providing lossless handover while keeping acceptable delays. The second objective of this paper is to design a new TCP snoop agent (TCP Snoop, which interacts with the IW layer in order to mitigate BDP (Bandwidth Delay Product mismatch and to solve spurious RTO (Retransmission TimeOut problems. The cross-layer effects on the handover performance are evaluated by simulations. Our results show that cross-layer interaction between IW layer and TCP Snoop smoothes the handover procedure for TCP traffics. Additionally, this novel inter-RAT cross-layer scheme has the merit of keeping existing TCP protocol stacks unchanged.

SNR Improvement Employing Dynamics Beamforming Based on Angle of Arrival for Mobile WiMax IEEE 802.16e

OpenAIRE

Yuwono, T

2014-01-01

The development of telecommunicationtechnology and services is very rapid. One oftelecommunication technology that is beingdeveloped is WiMax (Worldwide Interoperabilityfor Microwave Access). The advantages of WiMaxis it possess much range and can operate in non -LOS conditions. So it fits implemented inIndonesia to accelerate the internet penetration.Some features of WiMax technology is higherbandwidth and further range/area. SNRImprovement is The effort to increase the rangeand improve the ...

Ultrawideband Vivaldi Antenna for DVB-T, WLAN, and WiMAX Applications

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Dalia M. Elsheakh

2014-01-01

Full Text Available Compact Vivaldi patch antenna with a parasitic meander line is presented in this paper. A PIN diode switch is used to connect and disconnect ultrahigh frequency band (UHF with ultrawide bandwidth (UWB. The operating frequencies can be switched among different services, depending on the switching states (ON/OFF to add the lower band when required. This antenna is suitable for portable DVB-T which extended from 450 MHz to 850 MHz receiver applications and the WLAN (Wireless Local Area Network IEEE 802.11b,g (5.1–5.8 GHz frequency bands and WiMAX band (3.3–3.8 GHz. The measured reflection coefficient of the proposed antenna is compared with the simulated one; good agreement is observed. Also, simulated radiation pattern of the antenna is presented. All simulations are carried out using the EM commercial simulator, high frequency structure simulator (HFSS ver.13.

Modeling and Simulation of Handover Scheme in Integrated EPON-WiMAX Networks

DEFF Research Database (Denmark)

Yan, Ying; Dittmann, Lars

2011-01-01

In this paper, we tackle the seamless handover problem in integrated optical wireless networks. Our model applies for the convergence network of EPON and WiMAX and a mobilityaware signaling protocol is proposed. The proposed handover scheme, Integrated Mobility Management Scheme (IMMS), is assisted...... by enhancing the traditional MPCP signaling protocol, which cooperatively collects mobility information from the front-end wireless network and makes centralized bandwidth allocation decisions in the backhaul optical network. The integrated network architecture and the joint handover scheme are simulated using...... OPNET modeler. Results show validation of the protocol, i.e., integrated handover scheme gains better network performances....

Bandwidth enhancement of monopole antenna with DGS for SHF and reconfigurable structure for WiMAX, WLAN and C-band applications

Science.gov (United States)

Beigi, P.; Mohammadi, P.

2017-11-01

In this study a reconfigurable antenna for WiMAX, WLAN, C-bands and SHF applications has been presented. The main body of antenna includes rectangular and L-shaped slotted ground plane and a rectangular patch with slotted feed line, for impedance bandwidth enhancement. In the proposed antenna, a PIN diode is used to adjust the frequency band to SHF, WiMAX, WLAN and C-bands applications. When PIN diode is forward-biased, the antenna covers the 3.5-31 GHz frequency range (i.e. a 160% bandwidth) and when the PIN diode is in its off-state, it operates between 3.4-5.8 GHz. The designed antenna, with a very small size of 12 × 18 × 1.6 mm3, has been fabricated and tested. The radiation pattern is approximately omnidirectional. Simulations and experimental results are in a good agreement with each other and suggest good performance for the presented antenna.

Connecting Land-Based Networks to Ships

Science.gov (United States)

2013-06-01

multipoint wireless broadband systems, and WiMAX networks were initially deployed for fixed and nomadic (portable) applications. These standards...CAPABILITIES OF SHIP-TO-SHORE COMMUNICATIONS A. US Navy Automated Digital Network System (ADNS) The U.S. Navy’s Automated Digital Network System (ADNS...submit digitally any necessary documents to the terminal operators, contact their logistics providers, access tidal information and receive

On the Modelling of the Mobile WiMAX (IEEE 802.16e Uplink Scheduler

Directory of Open Access Journals (Sweden)

Darmawaty Mohd Ali

2010-01-01

Full Text Available Packet scheduling has drawn a great deal of attention in the field of wireless networks as it plays an important role in distributing shared resources in a network. The process involves allocating the bandwidth among users and determining their transmission order. In this paper an uplink (UL scheduling algorithm for the Mobile Worldwide Interoperability for Microwave Access (WiMAX network based on the cyclic polling model is proposed. The model in this study consists of five queues (UGS, ertPS, rtPS, nrtPS, and BE visited by a single server. A threshold policy is imposed to the nrtPS queue to ensure that the delay constraint of real time traffic (UGS, ertPS, and rtPS is not violated making this approach original in comparison to the existing contributions. A mathematical model is formulated for the weighted sum of the mean waiting time of each individual queues based on the pseudo-conservation law. The results of the analysis are useful in obtaining or testing approximation for individual mean waiting time especially when queues are asymmetric (where each queue may have different stochastic characteristic such as arrival rate and service time distribution and when their number is large (more than 2 queues.

Dynamic ad hoc networks

CERN Document Server

Rashvand, Habib

2013-01-01

Motivated by the exciting new application paradigm of using amalgamated technologies of the Internet and wireless, the next generation communication networks (also called 'ubiquitous', 'complex' and 'unstructured' networking) are changing the way we develop and apply our future systems and services at home and on local, national and global scales. Whatever the interconnection - a WiMAX enabled networked mobile vehicle, MEMS or nanotechnology enabled distributed sensor systems, Vehicular Ad hoc Networking (VANET) or Mobile Ad hoc Networking (MANET) - all can be classified under new networking s

Effective Scheme of Channel Tracking and Estimation for Mobile WiMAX DL-PUSC System

Directory of Open Access Journals (Sweden)

Phuong Thi Thu Pham

2010-01-01

Full Text Available This paper introduces an effective joint scheme of channel estimation and tracking for downlink partial usage of subchannel (DL-PUSC mode of mobile WiMAX system. Based on the pilot pattern of this particular system, some channel estimation methods including conventional interpolations and a more favorable least-squares line fitting (LSLF technique are comparatively studied. Besides, channel estimation performance can be remarkably improved by taking advantage of channel tracking derived from the preamble symbol. System performances in terms of packet error rate (PER and user link throughput are investigated in various channels adopted from the well-known ITU models for mobile environments. Simulation results show a significant performance enhancement when the proposed joint scheme is utilized, at least 5 dB, compared to only commonly used channel estimation approaches.

A subjective scheduler for subjective dedicated networks

Science.gov (United States)

Suherman; Fakhrizal, Said Reza; Al-Akaidi, Marwan

2017-09-01

Multiple access technique is one of important techniques within medium access layer in TCP/IP protocol stack. Each network technology implements the selected access method. Priority can be implemented in those methods to differentiate services. Some internet networks are dedicated for specific purpose. Education browsing or tutorial video accesses are preferred in a library hotspot, while entertainment and sport contents could be subjects of limitation. Current solution may use IP address filter or access list. This paper proposes subjective properties of users or applications are used for priority determination in multiple access techniques. The NS-2 simulator is employed to evaluate the method. A video surveillance network using WiMAX is chosen as the object. Subjective priority is implemented on WiMAX scheduler based on traffic properties. Three different traffic sources from monitoring video: palace, park, and market are evaluated. The proposed subjective scheduler prioritizes palace monitoring video that results better quality, xx dB than the later monitoring spots.

Simultaneous transmission of 256-QAM WIMAX at 5.7GHz and optically generated impulse radio UWB over fiber for indoor wireless multi-services

DEFF Research Database (Denmark)

Yu, Xianbin; Yin, Xiaoli; Gibbon, Timothy Braidwood

2010-01-01

Fiber transmission of simultaneous optically generated FCC compliant 625Mbps impulse radio UWB and 80Mbps 256-QAM IEEE 802.16 WIMAX signals is experimentally demonstrated by using a single directly modulated light source.......Fiber transmission of simultaneous optically generated FCC compliant 625Mbps impulse radio UWB and 80Mbps 256-QAM IEEE 802.16 WIMAX signals is experimentally demonstrated by using a single directly modulated light source....

Performance evaluation of cognitive radio in advanced metering infrastructure communication

Science.gov (United States)

Hiew, Yik-Kuan; Mohd Aripin, Norazizah; Din, Norashidah Md

2016-03-01

Smart grid is an intelligent electricity grid system. A reliable two-way communication system is required to transmit both critical and non-critical smart grid data. However, it is difficult to locate a huge chunk of dedicated spectrum for smart grid communications. Hence, cognitive radio based communication is applied. Cognitive radio allows smart grid users to access licensed spectrums opportunistically with the constraint of not causing harmful interference to licensed users. In this paper, a cognitive radio based smart grid communication framework is proposed. Smart grid framework consists of Home Area Network (HAN) and Advanced Metering Infrastructure (AMI), while AMI is made up of Neighborhood Area Network (NAN) and Wide Area Network (WAN). In this paper, the authors only report the findings for AMI communication. AMI is smart grid domain that comprises smart meters, data aggregator unit, and billing center. Meter data are collected by smart meters and transmitted to data aggregator unit by using cognitive 802.11 technique; data aggregator unit then relays the data to billing center using cognitive WiMAX and TV white space. The performance of cognitive radio in AMI communication is investigated using Network Simulator 2. Simulation results show that cognitive radio improves the latency and throughput performances of AMI. Besides, cognitive radio also improves spectrum utilization efficiency of WiMAX band from 5.92% to 9.24% and duty cycle of TV band from 6.6% to 10.77%.

A multi-attribute vertical handoff scheme for heterogeneous wireless networks

Directory of Open Access Journals (Sweden)

JI Xiaolong

2014-04-01

Full Text Available In order to meet the user demand for different services as well as to mitigate the Ping-pong effect caused by vertical handoff for wireless network,a multi-attribute vertical handoff scheme for heterogeneous wireless network is proposed.In the algorithm,a fuzzy logic method is used to make pre-decision.The optimal handoff target network is selected by a cost function of network which uses an Analytic Hierarchy Process to calculate the weights of SNR,delay,cost and user preference in different business scenarios.Simulation is performed in the environment which is overlapped by WiMAX and UMTS networks.Results show that the proposed approach can effectively reduce the number of handoff and power consumption in a condition to satisfy the user needs.

Energy-signal quality trade-offs in a WiMAX mobile station with a booster amplifier

Science.gov (United States)

Suherman; Mubarakah, N.; Wiranata, O.; Kasim, S. T.

2018-02-01

Worldwide Interoperability for Microwave Access (WiMAX) is a broadband wireless access technology that is able to provide high bit rate mobile internet services. Battery endurance remains a problem in current mobile communication. On the other hand, signal quality determines the successful run of the mobile applications. Energy consumption optimization cannot sacrifice the signal level required by the application to run smoothly. On the contrary, the application should consider battery life time. This paper examines the tradeoffs between energy and signal quality in WiMAX subscriber station by adjusting signal level using a booster amplifier. Simulation evaluations show that an increment of 0.00000104% energy consumption on using amplifier adaptively produces 16.411% signal to noise ratio (SNR) increment and 10.7% bit error rate (BER) decrement. By keeping the amplifier turned on, energy consumption increases up to 0.00000136%, causing the SNR rises to 17.2638% and BER drops to 11.13%. The evaluated application is video streaming, other application may behave differently.

Integración de las redes ópticas pasivas Ethernet EPON/GPON con la tecnología WiMAX . (Artículo)

OpenAIRE

Logroño Gómez, Jorge Israel

2009-01-01

El presente proyecto está orientado al estudio de las redes EPON/GPON y su integración con la tecnología WiMAX. Este artículo inicia con un estudio de las características generales sobre la Convergencia Fijo-Móvil (CFM), sus razones en este proceso de continuo cambio en las telecomunicaciones y de manera general las características del desarrollo de la tecnología WiMAX (Worldwide Interoperability for Microwave Access) como tecnología de acceso de banda ancha inalámbrica. Posteriormente se inc...

The promise of downlink MU-MIMO for high-capacity next generation mobile broadband networks based on IEEE 802.16 m

OpenAIRE

Papathanassiou Apostolos; Davydov Alexei

2011-01-01

Abstract The dramatic increase of the demand for mobile broadband services poses stringent requirements on the performance evolution of currently deployed mobile broadband networks, such as Mobile WiMAX Release 1 and 3GPP LTE Release 8. Although the combination of single-user multiple-input multiple-output (SU-MIMO) and orthogonal frequency division multiple access (OFDMA) provide the appropriate technologies for improving the downlink performance of third generation (3G) code division multip...

Hierarchical Downlink Resource Management Framework for OFDMA based WiMAX Systems

DEFF Research Database (Denmark)

Wang, Hua; Iversen, Villy Bæk

2008-01-01

IEEE 802.16, known as WiMAX, has received much attention for its capability to support multiple types of applications with diverse QoS requirements. Beyond what the standard has defined, radio resource management (RRM) still remains an open issue. In this paper, we propose a hierarchical downlink...... belonging to different service classes with the objective of increasing the spectral efficiency while satisfying the diverse QoS requirements in each service class. CAC highlights how to limit the number of ongoing connections preventing the system capacity from being overused. Through system...

Public Safety Broadband Network Architecture Description

Science.gov (United States)

2013-08-01

could be used to add an in-app purchase to the user’s mobile phone bill. Major operators , such as AT& T , Deutsche Telekom, Orange, Telefonica and...3GPP technologies such as CDMA2000 and WiMAX networks. MME Mobility Managemen t Entity The MME is the key control-node for the LTE access-network... operator ( operator -managed small cells, etc.) or provides sufficient security (authentication, encryption, etc.). See Figure D3. Figure D3: ITU- T

Video Classification and Adaptive QoP/QoS Control for Multiresolution Video Applications on IPTV

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Huang Shyh-Fang

2012-01-01

Full Text Available With the development of heterogeneous networks and video coding standards, multiresolution video applications over networks become important. It is critical to ensure the service quality of the network for time-sensitive video services. Worldwide Interoperability for Microwave Access (WIMAX is a good candidate for delivering video signals because through WIMAX the delivery quality based on the quality-of-service (QoS setting can be guaranteed. The selection of suitable QoS parameters is, however, not trivial for service users. Instead, what a video service user really concerns with is the video quality of presentation (QoP which includes the video resolution, the fidelity, and the frame rate. In this paper, we present a quality control mechanism in multiresolution video coding structures over WIMAX networks and also investigate the relationship between QoP and QoS in end-to-end connections. Consequently, the video presentation quality can be simply mapped to the network requirements by a mapping table, and then the end-to-end QoS is achieved. We performed experiments with multiresolution MPEG coding over WIMAX networks. In addition to the QoP parameters, the video characteristics, such as, the picture activity and the video mobility, also affect the QoS significantly.

A Compact Frequency Reconfigurable Hybrid DRA for LTE/Wimax Applications

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Sajid Aqeel

2017-01-01

Full Text Available A compact hybrid antenna structure with frequency reconfiguration capabilities is presented in this article. The proposed design employs a combination of a rectangular DR element and a coupling slot on the structure’s ground plane (GP. The slot shifts the fundamental DRA mode by introducing a slow wave effect and its resonant behavior helps to achieve an omnidirectional pattern at low frequencies. The slot is loaded with a series of PIN diode switches whose ON/OFF combinations alter the effective slot length. Slot loading with PIN diodes results in frequency reconfiguration of the proposed structure with a large tuning range of 76.2% (between 1.73 and 3.86 GHz. A parametric analysis was performed to investigate the effects of slot length, width, and position on the reflection coefficients of the proposed structure. A prototype of the proposed design was fabricated and results were measured. The measured results show a close agreement with the simulated ones. The proposed design is suitable for DCS 1800 MHz, PCS 1900 MHZ, UMTS, LTE 2500–2700 MHz, and Wimax 3.5 GHz.

A Reconfigurable WiMAX Antenna for Directional and Broadside Application

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M. Jusoh

2013-01-01

Full Text Available A novel reconfigurable compact patch array antenna for directional and broadside application is proposed. The presented antenna has successfully been able to function for directional beam at 320° or 35° and divisive broadside beam at 43° and 330°. This is realized in the unique form of aperture coupled spiral feeding technique and positioning of the radiating elements at 0°, 90,° and 180°. The switchable feature is effectively performed by the configuration of three PIN diodes. All PIN diodes are positioned at the specific location of the aperture coupled structure. It is discovered in simulation that the switches can be represented with a copper strip line or touchstone (TS block . The proposed antenna design operates at 2.37 GHz to 2.41 GHz and has a maximum gain of 6.4 dB and efficiency of 85.97%. Such antenna produces a broadside HPBW with a wider bandwidth covering from −90° to 90° compared to the normal microstrip antenna which could only provide HPBW of −50° to 50°. Moreover, the proposed antenna has small physical dimension of 100 mm by 100 mm. The simulation and measurement results have successfully exhibited the idea of the presented antenna performance. Therefore, the antenna is sufficiently competent in the smart WiMAX antenna application.

Planning of Efficient Wireless Access with IEEE 802.16 for Connecting Home Network to the Internet

Directory of Open Access Journals (Sweden)

Pichet Ritthisoonthorn

2010-01-01

Full Text Available The emergence of IEEE802.16 wireless standard technology (WiMAX has significantly increased the choice to operators for the provisioning of wireless broadband access network. WiMAX is being deployed to compliment with xDSL in underserved or lack of the broadband network area, in both developed and developing countries. Many incumbent operators in developing countries are considering the deployment of WiMAX as part of their broadband access strategy. This paper presents an efficient and simple method for planning of broadband fixed wireless access (BFWA with IEEE802.16 standard to support home connection to Internet. The study formulates the framework for planning both coverage and capacity designs. The relationship between coverage area and access rate from subscriber in each environment area is presented. The study also presents the throughput and channel capacity of IEEE802.16 in different access rates. An extensive analysis is performed and the results are applied to the real case study to demonstrate the practicality of using IEEE 802.16 for connecting home to Internet. Using empirical data and original subscriber traffic from measurement, it is shown that the BFWA with IEEE802.16 standard is a capacity limited system. The capacity of IEEE802.16 is related to different factors including frequency bandwidth, spectrum allocation, estimation of traffic per subscriber, and choice of adaptive modulation from subscriber terminal. The wireless access methods and procedures evolved in this research work and set out in this paper are shown to be well suited for planning BFWA system based on IEEE802.16 which supports broadband home to Internet connections.

Analysis of Blocking Rate and Bandwidth Usage of Mobile IPTV Services in Wireless Cellular Networks

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Mingfu Li

2014-01-01

Full Text Available Mobile IPTV services over wireless cellular networks become more and more popular, owing to the significant growth in access bandwidth of wireless cellular networks such as 3G/4G and WiMAX. However, the spectrum resources of wireless cellular networks is rare. How to enhance the spectral efficiency of mobile networks becomes an important issue. Unicast, broadcast, and multicast are the most important transport schemes for offering mobile IPTV services over wireless cellular networks. Therefore, bandwidth usages and blocking rates of unicast, broadcast, and multicast IPTV services were analyzed and compared in this paper. Simulations were also conducted to validate the analytical results. Numerical results demonstrate that the presented analysis is correct, and multicast scheme achieves the best bandwidth usage and blocking rate performance, relative to the other two schemes.

Analysis of blocking rate and bandwidth usage of mobile IPTV services in wireless cellular networks.

Science.gov (United States)

Li, Mingfu

2014-01-01

Mobile IPTV services over wireless cellular networks become more and more popular, owing to the significant growth in access bandwidth of wireless cellular networks such as 3G/4G and WiMAX. However, the spectrum resources of wireless cellular networks is rare. How to enhance the spectral efficiency of mobile networks becomes an important issue. Unicast, broadcast, and multicast are the most important transport schemes for offering mobile IPTV services over wireless cellular networks. Therefore, bandwidth usages and blocking rates of unicast, broadcast, and multicast IPTV services were analyzed and compared in this paper. Simulations were also conducted to validate the analytical results. Numerical results demonstrate that the presented analysis is correct, and multicast scheme achieves the best bandwidth usage and blocking rate performance, relative to the other two schemes.

Wavelet networks for reducing the envelope fluctuations in WirelessMan–OFDM systems

Directory of Open Access Journals (Sweden)

Radouane Iqdour

2016-05-01

Full Text Available The IEEE 802.16d standard specified Orthogonal Frequency Division Multiplexing (OFDM modulation for the Worldwide Interoperability for Microwave Access (WiMAX physical layer. However, the main weakness of OFDM is the high Peak-to-Average Power Ratio (PAPR. In this paper, we present two new approaches based on Wavelet Networks (WNs for reducing the PAPR in the fixed WiMAX system. The training data is obtained from the ACE-AGP algorithm. The results of the simulations show the effectiveness of the proposed schemes even for high order modulation such as 64-QAM. Furthermore, the proposals allow reduction in the complexity and convergence time in comparison with other methods.

On the Verification of a WiMax Design Using Symbolic Simulation

Directory of Open Access Journals (Sweden)

Gabriela Nicolescu

2013-07-01

Full Text Available In top-down multi-level design methodologies, design descriptions at higher levels of abstraction are incrementally refined to the final realizations. Simulation based techniques have traditionally been used to verify that such model refinements do not change the design functionality. Unfortunately, with computer simulations it is not possible to completely check that a design transformation is correct in a reasonable amount of time, as the number of test patterns required to do so increase exponentially with the number of system state variables. In this paper, we propose a methodology for the verification of conformance of models generated at higher levels of abstraction in the design process to the design specifications. We model the system behavior using sequence of recurrence equations. We then use symbolic simulation together with equivalence checking and property checking techniques for design verification. Using our proposed method, we have verified the equivalence of three WiMax system models at different levels of design abstraction, and the correctness of various system properties on those models. Our symbolic modeling and verification experiments show that the proposed verification methodology provides performance advantage over its numerical counterpart.

Driven-Walking for Visually Impaired/Blind People through WiMAX

Directory of Open Access Journals (Sweden)

Panagiotis GIOANNIS

2010-03-01

Full Text Available It is known that people who are blind/visually impaired find it difficult to move, especially in unknown places. Usually the only help they have is their walking stick (white cane, a guide dog and sometimes special warning sounds or road signals at specific positions. Material and Method: In this paper we are trying to find a solution on how to build an appropriate navigating system for blind people. Results: Based on benefits of powerful properties of mobile WiMAX standard we suggest an important navigate application which can translate a digital visual environment properly for blind/visually impaired users through a plethora of combinations such as voice, brain or tongue signals. Conclusions: We believe that such an idea will be an initial point for a plethora of applications which will eliminate walking disabilities of blind/visually people.

Multistandard wireless transmission over SSMF and large-core POF for access and in-home networks

NARCIS (Netherlands)

Shi, Y.; Morant, M.; Okonkwo, C.M.; Llorente, R.; Tangdiongga, E.; Koonen, A.M.J.

2012-01-01

An end-to-end transmission of coexisting multistandard radio (LTE, WiMAX, and UWB) signals is demonstrated for the first time with the transmission over a combined access and in-home networks consisting of 25-km SSMF, 25-m large-core diameter polymethylmethacrylate graded-index plastic optical fiber

Modeling Multistandard Wireless Networks in OPNET

DEFF Research Database (Denmark)

Zakrzewska, Anna; Berger, Michael Stübert; Ruepp, Sarah Renée

2011-01-01

Future wireless communication is emerging towards one heterogeneous platform. In this new environment wireless access will be provided by multiple radio technologies that are cooperating and complementing one another. The paper investigates the possibilities of developing such a multistandard sys...... system using OPNET Modeler. A network model consisting of LTE interworking with WLAN and WiMAX is considered from the radio resource management perspective. In particular, implementing a joint packet scheduler across multiple systems is discussed more in detail....

Optimal Pricing Strategy for Wireless Social Community Networks

OpenAIRE

Mazloumian, Amin; Manshaei, Mohammad Hossein; Felegyhazi, Mark; Hubaux, Jean-Pierre

2008-01-01

The increasing number of mobile applications fuels the demand for affordable and ubiquitous wireless access. The traditional wireless network technologies such as EV-DO or WiMAX provide this service but require a huge upfront investment in infrastructure and spectrum. On the contrary, as they do not have to face such an investment, social community operators rely on subscribers who constitute a community of users. The pricing strategy of the provided wireless access is an open problem for thi...

The Audacity of Fiber-Wireless (FiWi) Networks

Science.gov (United States)

Maier, Martin; Ghazisaidi, Navid; Reisslein, Martin

A plethora of enabling optical and wireless technologies have been emerging that can be used to build future-proof bimodal fiber-wireless (FiWi) broadband access networks. After overviewing key enabling radio-over-fiber (RoF) and radio-and-fiber (R&F) technologies and briefly surveying the state of the art of FiWi networks, we introduce an Ethernet-based access-metro FiWi network, called SuperMAN, that integrates next-generation WiFi and WiMAX networks with WDM-enhanced EPON and RPR networks. Throughout the paper we pay close attention to the technical challenges and opportunities of FiWi networks, but also elaborate on their societal benefits and potential to shift the current research focus from optical-wireless networking to the exploitation of personal and in-home computing facilities to create new unforeseen services and applications as we are about to enter the Petabyte age.

Simulasi dan Analisis Transmisi Multihop Mobile WiMAX Dengan Metode Hybrid

Directory of Open Access Journals (Sweden)

Muhamad Asvial

2016-06-01

Full Text Available Makalah ini membahas tentang pengembangan relay station untuk transmisi downlink Mobile WiMAX dengan menggunakan metode hybrid, yaitu metode transmisi yang menggunakan tiga buah transmisi. Ketiga transmisi tersebut yaitu dua buah transmisi yang melewati relay station terlebih dahulu baru ke receiver dan satu buah transmisi langsung dari pengirim ke penerima. Pada relay station ada dua kondisi yang berlaku, yaitu Decode and Forward (DF dan Amplify and Forward (AF. Hasil simulasi menunjukkan bahwa ketika Relay Station dalam mode forwarding Amplify and Forward (AF akan memperoleh BER yang kecil sehingga throughput besar dan merupakan perfomansi yang terbaik. Ketika masing-masing relay station diatur agar menggunakan mode forwarding yang berbeda, misalnya AF pada relay station 1 dan DF pada Relay Station 2 atau sebaliknya akan memperoleh hasil yang sama. Sedangkan ketika kedua relay station diatur untuk menggunakan mode forwarding Decode and Forward (DF, maka BER yang dihasilkan besar dan throughput-nya pun kecil, dan kondisi ini merupakan yang terburuk.

Regressive Prediction Approach to Vertical Handover in Fourth Generation Wireless Networks

Directory of Open Access Journals (Sweden)

Abubakar M. Miyim

2014-11-01

Full Text Available The over increasing demand for deployment of wireless access networks has made wireless mobile devices to face so many challenges in choosing the best suitable network from a set of available access networks. Some of the weighty issues in 4G wireless networks are fastness and seamlessness in handover process. This paper therefore, proposes a handover technique based on movement prediction in wireless mobile (WiMAX and LTE-A environment. The technique enables the system to predict signal quality between the UE and Radio Base Stations (RBS/Access Points (APs in two different networks. Prediction is achieved by employing the Markov Decision Process Model (MDPM where the movement of the UE is dynamically estimated and averaged to keep track of the signal strength of mobile users. With the help of the prediction, layer-3 handover activities are able to occur prior to layer-2 handover, and therefore, total handover latency can be reduced. The performances of various handover approaches influenced by different metrics (mobility velocities were evaluated. The results presented demonstrate good accuracy the proposed method was able to achieve in predicting the next signal level by reducing the total handover latency.

Modified weighted fair queuing for packet scheduling in mobile WiMAX networks

Science.gov (United States)

Satrya, Gandeva B.; Brotoharsono, Tri

2013-03-01

The increase of user mobility and the need for data access anytime also increases the interest in broadband wireless access (BWA). The best available quality of experience for mobile data service users are assured for IEEE 802.16e based users. The main problem of assuring a high QOS value is how to allocate available resources among users in order to meet the QOS requirement for criteria such as delay, throughput, packet loss and fairness. There is no specific standard scheduling mechanism stated by IEEE standards, which leaves it for implementer differentiation. There are five QOS service classes defined by IEEE 802.16: Unsolicited Grant Scheme (UGS), Extended Real Time Polling Service (ertPS), Real Time Polling Service (rtPS), Non Real Time Polling Service (nrtPS) and Best Effort Service (BE). Each class has different QOS parameter requirements for throughput and delay/jitter constraints. This paper proposes Modified Weighted Fair Queuing (MWFQ) scheduling scenario which was based on Weighted Round Robin (WRR) and Weighted Fair Queuing (WFQ). The performance of MWFQ was assessed by using above five QoS criteria. The simulation shows that using the concept of total packet size calculation improves the network's performance.

Network survivability performance

Science.gov (United States)

1993-11-01

This technical report has been developed to address the survivability of telecommunications networks including services. It responds to the need for a common understanding of, and assessment techniques for network survivability, availability, integrity, and reliability. It provides a basis for designing and operating telecommunications networks to user expectations for network survivability and a foundation for continuing industry activities in the subject area. This report focuses on the survivability of both public and private networks and covers a wide range of users. Two frameworks are established for quantifying and categorizing service outages, and for classifying network survivability techniques and measures. The performance of the network survivability techniques is considered; however, recommended objectives are not established for network survivability performance.

A CPW-fed Triple-band Antenna for WLAN and WiMAX Applications

Directory of Open Access Journals (Sweden)

X.L.Yang

2014-12-01

Full Text Available In this letter, a compact printed antenna fed by coplanar waveguide for triple-band is presented. The proposed antenna consists of two rectangular metallic loops in front and a slit square ring on the backside. Tri-band has been achieved, which can be easily tuned by adjusting the sizes of the rectangles. An analysis of equal lumped circuit mechanism as well the triple band operation is provided. Key parameters to tune the resonant frequencies have been identified. The overall dimension of the proposed antenna is 30×26 mm^2. Simulated results show that the presented antenna can cover three separated impedance bandwidths of ～13% at 300 MHz (2.2–2.5 GHz, ～14% at 500 MHz (3.3–3.8 GHz, and ～15% at 800 MHz (5.1–5.9 GHz, which are well applied for both 2.4/5.2/5.8-GHz WLAN bands and 3.5/5.5-GHz WiMAX bands.

An Adaptive Power Efficient Packet Scheduling Algorithm for Wimax Networks

OpenAIRE

R Murali Prasad; P. Satish Kumar

2010-01-01

Admission control schemes and scheduling algorithms are designed to offer QoS services in 802.16/802.16e networks and a number of studies have investigated these issues. But the channel condition and priority of traffic classes are very rarely considered in the existing scheduling algorithms. Although a number of energy saving mechanisms have been proposed for the IEEE 802.16e, to minimize the power consumption of IEEE 802.16e mobile stations with multiple real-time connections has not yet be...

High-Performance Networking

CERN Multimedia

CERN. Geneva

2003-01-01

The series will start with an historical introduction about what people saw as high performance message communication in their time and how that developed to the now to day known "standard computer network communication". It will be followed by a far more technical part that uses the High Performance Computer Network standards of the 90's, with 1 Gbit/sec systems as introduction for an in depth explanation of the three new 10 Gbit/s network and interconnect technology standards that exist already or emerge. If necessary for a good understanding some sidesteps will be included to explain important protocols as well as some necessary details of concerned Wide Area Network (WAN) standards details including some basics of wavelength multiplexing (DWDM). Some remarks will be made concerning the rapid expanding applications of networked storage.

UWB Monopole Antenna with Band Notched Characteristics Mitigating Interference with WiMAX

Directory of Open Access Journals (Sweden)

A. A. Ibrahim

2017-06-01

Full Text Available Compact asymmetric coplanar strip (ACS - fed monopole antenna is presented in this paper for operation in ultra wide-band (UWB applications. The antenna is composed of a semi-elliptical monopole and lateral coplanar ground plane to operate in the UWB range. It occupies a very small size of 28 × 11.5 mm 2 and is mounted on low cost FR4 substrate of 1.6 mm thickness and dielectric constant of 4.4. Band notched structure is applied to the proposed antenna to assure the rejection of WiMAX frequency band centered at 3.5 GHz to minimize the interference of the communication system with this service. The radiation characteristics of the proposed ACS-fed monopole antenna is nearly omnidirectional with moderate gain over the entire UWB frequency range. The measurements of the fabricated model confirm the designed behavior. The compactness in size, cheap cost and simple feeding technique make it as a good candidate to be integrated within the portable devices for wireless communication.

REDISTRIBUTION OF BASE STATIONS LOAD IN MOBILE COMMUNICATION NETWORKS

Directory of Open Access Journals (Sweden)

Igor Ruban

2017-09-01

Full Text Available The subject matter of the article is the processes of load distribution in mobile communication networks. The object of research is the handover. The goal is to develop a method for redistributing the load between neighboring areas for mobile nodes. The considered base stations are supposed to have the signal-to-noise ratios that are equal or close. The methods that are used: methods of system analysis, methods of digital signal processing. The following results are obtained. The method that allows mobile nodes, whose signal-to-noise ratios are equal or close, to switch to a less loaded base station. This method allows the base station to launch the handover process enabling more even distribution of the load from mobile nodes among neighboring base stations in wireless and mobile networks. In the suggested modification of the method, the function assessing the bandwidth of the uplink channel is added to the base stations, as well a threshold value for using its bandwidth. Thus, when the current value of bandwidth reaches the threshold, the base station starts sending out a message to all mobile nodes and verifies free neighboring areas for switching over mobile nodes. If there are adjacent areas with a lower load, the base station notifies all potential candidates about the necessity of their switching over. The handover process is launched when the available bandwidth of the base station decreases below a certain threshold. Therefore, it is possible to optimize the operation of the WiMAX network with respect to the criterion of the total bandwidth capacity of the base stations. Besides, the results of the comparative analysis of the handover process in networks based on the WiMAX technology that are obtained using the OpNet simulation environment are presented. Conclusions.The suggested approach can be used to improve the basic software of mobile communication networks. When moving a node from one area to another one in access servers, the

Diagnosing Anomalous Network Performance with Confidence

Energy Technology Data Exchange (ETDEWEB)

Settlemyer, Bradley W [ORNL; Hodson, Stephen W [ORNL; Kuehn, Jeffery A [ORNL; Poole, Stephen W [ORNL

2011-04-01

Variability in network performance is a major obstacle in effectively analyzing the throughput of modern high performance computer systems. High performance interconnec- tion networks offer excellent best-case network latencies; how- ever, highly parallel applications running on parallel machines typically require consistently high levels of performance to adequately leverage the massive amounts of available computing power. Performance analysts have usually quantified network performance using traditional summary statistics that assume the observational data is sampled from a normal distribution. In our examinations of network performance, we have found this method of analysis often provides too little data to under- stand anomalous network performance. Our tool, Confidence, instead uses an empirically derived probability distribution to characterize network performance. In this paper we describe several instances where the Confidence toolkit allowed us to understand and diagnose network performance anomalies that we could not adequately explore with the simple summary statis- tics provided by traditional measurement tools. In particular, we examine a multi-modal performance scenario encountered with an Infiniband interconnection network and we explore the performance repeatability on the custom Cray SeaStar2 interconnection network after a set of software and driver updates.

2011 Special Operations Forces Industry Conference

Science.gov (United States)

2011-05-19

Fixed Operators Wateen : First nationwide WiMAX 4G deployment in the world (Nov 2008) UNCLASSIFIED UNCLASSIFIED 13 Mobile WiMax Phones Samsung (Korea...Currently 582 operators in 150 countries • $1.2 B investment planned for 2011 (China, US, Taiwan, Korea, Malaysia ) • Coverage of 823 mil persons end of 2010...Steam! • January 2010 – First public LTE network operational in Stockholm/Oslo – Uses Samsung devices, Ericsson network core – 50 Mbps download, 20

WIRELESS TECHNOLOGIES for LOCATION-BASED SERVICES

Directory of Open Access Journals (Sweden)

Dewi Wirastuti

2012-06-01

Full Text Available This paper presents an overview of wireless technologies that support location-based services (LBS. Satellite and cellular networks have exploited their communication infrastructure to offer LBS. The rapid deployment of mobile broadband wireless networks has offered another appealing application area. Key to the realisation of LBS is an efficient and accurate positioning technique with various methods and offering different performance levels. So far, Global Positioning System (GPS has offered the best accuracy at a low cost but it is challenged by poor indoor coverage. With the rapid deployment of broadband wireless access ubiquitously, Mobile WiMAX (Worldwide Interoperability for Microwave Access is seen as a potential positioning option for LBS. Some key features of WiMAX, i.e., broadband benefit, high speed and large coverage area; it will be exploited to provide LBS.

Uplink scheduling and adjacent-channel coupling loss analysis for TD-LTE deployment.

Science.gov (United States)

Yeo, Woon-Young; Moon, Sung Ho; Kim, Jae-Hoon

2014-01-01

TD-LTE, one of the two duplexing modes in LTE, operates in unpaired spectrum and has the advantages of TDD-based technologies. It is expected that TD-LTE will be more rapidly deployed in near future and most of WiMax operators will upgrade their networks to TD-LTE gradually. Before completely upgrading to TD-LTE, WiMax may coexist with TD-LTE in an adjacent frequency band. In addition, multiple TD-LTE operators may deploy their networks in adjacent bands. When more than one TDD network operates in adjacent frequency bands, severe interference may happen due to adjacent channel interference (ACI) and unsynchronized operations. In this paper, coexistence issues between TD-LTE and other systems are analyzed and coexistence requirements are provided. This paper has three research objectives. First, frame synchronization between TD-LTE and WiMax is discussed by investigating possible combinations of TD-LTE and WiMax configurations. Second, an uplink scheduling algorithm is proposed to utilize a leakage pattern of ACI in synchronized operations. Third, minimum requirements for coexistence in unsynchronized operations are analyzed by introducing a concept of adjacent-channel coupling loss. From the analysis and simulation results, we can see that coexistence of TD-LTE with other TDD systems is feasible if the two networks are synchronized. For the unsynchronized case, some special cell-site engineering techniques may be required to reduce the ACI.

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 successfull...... 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....

Multistandard Radio Systems: State of the Art and Research Issues

DEFF Research Database (Denmark)

Zakrzewska, Anna; Berger, Michael Stübert; Ruepp, Sarah Renée

2010-01-01

Integration of various wireless standards and building one consistent and compatible broadband system is a trend in wireless communication nowadays. This work focuses on multistandard networks enabling the cooperation between LTE and WiMAX systems. It presents the general vision on multistandard ...... systems and current possibilities of such integration. Furthermore, key features and challenges of developing this kind of network are discussed along with the proposed solutions and their performance benefits....

performance performance analysis of gsm networks in minna

African Journals Online (AJOL)

eobe

in terms of key performance indicators (KPI) based on statistics performance indicators ... in this study. Keywords: GSM Network, Drive Test, KPI and Radio Frequency Network Optimization. 1. .... message (SMS) traffic or in scenarios where so.

Network performance analysis

CERN Document Server

Bonald, Thomas

2013-01-01

The book presents some key mathematical tools for the performance analysis of communication networks and computer systems.Communication networks and computer systems have become extremely complex. The statistical resource sharing induced by the random behavior of users and the underlying protocols and algorithms may affect Quality of Service.This book introduces the main results of queuing theory that are useful for analyzing the performance of these systems. These mathematical tools are key to the development of robust dimensioning rules and engineering methods. A number of examples i

Method of modeling the cognitive radio using Opnet Modeler

OpenAIRE

Yakovenko, I. V.; Poshtarenko, V. M.; Kostenko, R. V.

2012-01-01

This article is a review of the first wireless standard based on cognitive radio networks. The necessity of wireless networks based on the technology of cognitive radio. An example of the use of standard IEEE 802.22 in Wimax network through which was implemented in the simulation software environment Opnet Modeler. Schedules to check the performance of HTTP and FTP protocols CR network. Simulation results justify the use of standard IEEE 802.22 in wireless networks. Ця стаття являє собою о...

An investigation and comparison on network performance analysis

OpenAIRE

Lanxiaopu, Mi

2012-01-01

This thesis is generally about network performance analysis. It contains two parts. The theory part summarizes what network performance is and inducts the methods of doing network performance analysis. To answer what network performance is, a study into what network services are is done. And based on the background research, there are two important network performance metrics: Network delay and Throughput should be included in network performance analysis. Among the methods of network a...

High Dynamic Range RF Front End with Noise Cancellation and Linearization for WiMAX Receivers

Directory of Open Access Journals (Sweden)

J.-M. Wu

2012-06-01

Full Text Available This research deals with verification of the high dynamic range for a heterodyne radio frequency (RF front end. A 2.6 GHz RF front end is designed and implemented in a hybrid microwave integrated circuit (HMIC for worldwide interoperability for microwave access (WiMAX receivers. The heterodyne RF front end consists of a low-noise amplifier (LNA with noise cancellation, an RF bandpass filter (BPF, a downconverter with linearization, and an intermediate frequency (IF BPF. A noise canceling technique used in the low-noise amplifier eliminates a thermal noise and then reduces the noise figure (NF of the RF front end by 0.9 dB. Use of a downconverter with diode linearizer also compensates for gain compression, which increases the input-referred third-order intercept point (IIP3 of the RF front end by 4.3 dB. The proposed method substantially increases the spurious-free dynamic range (DRf of the RF front end by 3.5 dB.

Social Networks and Sales Performance

Directory of Open Access Journals (Sweden)

Danny Pimentel Claro

2011-05-01

Full Text Available This paper argues that an informal network can itself be a basis for the increase in a sales manager’s performance. Informal networks create a structure that surpasses the formal hierarchical structure defined by the firm. We concentrated on the advice network and considered two different views of network structure that claim to have impact on performance. To explore this claim, we examined whether sales managers develop either a highly cohesive network structure (i.e. Coleman’s view or one containing structural holes (i.e. Burt’s view in order to achieve higher sales. We also investigated the matter of tie strength put forward by Granovetter in his seminal 1973 work. Census data was collected from about 500 personnel from an agricultural input retailer having 23 divisions. Estimates from a sample of 101 sales managers showed the importance of a highly cohesive structure (degree centrality for the three measures of sales manager’s performance. The strong ties have a positive impact on performance, suggesting the importance of building up strong bonds with network contacts. Sales managers’ age, time within the retailer and education also influence performance. These results imply that firms should stimulate contacts among personnel to spread technical and commercial information.

Network Performance Improvement under Epidemic Failures in Optical Transport Networks

DEFF Research Database (Denmark)

Fagertun, Anna Manolova; Ruepp, Sarah Renée

2013-01-01

In this paper we investigate epidemic failure spreading in large- scale GMPLS-controlled transport networks. By evaluating the effect of the epidemic failure spreading on the network, we design several strategies for cost-effective network performance improvement via differentiated repair times....... First we identify the most vulnerable and the most strategic nodes in the network. Then, via extensive simulations we show that strategic placement of resources for improved failure recovery has better performance than randomly assigning lower repair times among the network nodes. Our OPNET simulation...... model can be used during the network planning process for facilitating cost- effective network survivability design....

Numerical evaluation of human exposure to WiMax patch antenna in tablet or laptop.

Science.gov (United States)

Siervo, Beatrice; Morelli, Maria Sole; Landini, Luigi; Hartwig, Valentina

2018-04-30

The use of wireless communication devices, such as tablets or laptops, is increasing among children. Only a few studies assess specific energy absorption rate (SAR) due to exposure from wireless-enabled tablets and laptops, in particular with Worldwide Interoperability for Microwave Access (WiMax) technology. This paper reports the estimation of the interaction between an E-shaped patch antenna (3.5 GHz) and human models, by means of finite-difference time-domain (FDTD) method. Specifically, four different human models (young adult male, young adult female, pre-teenager female, male child) in different exposure conditions (antenna at different distances from the human model, in different positions, and orientations) were considered and whole-body, 10 and 1 g local SAR and magnetic field value (Bmax) were evaluated. From our results, in some worst-case scenarios involving male and female children's exposure, the maximum radiofrequency energy absorption (hot spots) is located in more sensitive organs such as eye, genitals, and breast. Bioelectromagnetics. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Analysis of Network Parameters Influencing Performance of Hybrid Multimedia Networks

Directory of Open Access Journals (Sweden)

Dominik Kovac

2013-10-01

Full Text Available Multimedia networks is an emerging subject that currently attracts the attention of research and industrial communities. This environment provides new entertainment services and business opportunities merged with all well-known network services like VoIP calls or file transfers. Such a heterogeneous system has to be able satisfy all network and end-user requirements which are increasing constantly. Therefore the simulation tools enabling deep analysis in order to find the key performance indicators and factors which influence the overall quality for specific network service the most are highly needed. This paper provides a study on the network parameters like communication technology, routing protocol, QoS mechanism, etc. and their effect on the performance of hybrid multimedia network. The analysis was performed in OPNET Modeler environment and the most interesting results are discussed at the end of this paper

A Wideband High-Gain Dual-Polarized Slot Array Patch Antenna for WiMAX Applications in 5.8 GHz

Directory of Open Access Journals (Sweden)

Amir Reza Dastkhosh

2012-01-01

Full Text Available A low-cost, easy-to-fabricate, wideband and high-gain dual-polarized array antenna employing an innovative microstrip slot patch antenna element is designed and fabricated. The design parameters of the antenna are optimized using commercial softwares (Microwave Office and Zeland IE3D to get the suitable -parameters and radiation patterns. Finally, the simulation results are compared to the experimental ones and a good agreement is demonstrated. The antenna has an approximately bandwidth of 14% (5.15–5.9 GHz which covers Worldwide Interoperability Microwave Access (WiMAX/5.8. It also has the peak gain of 26 dBi for both polarizations and high isolation between two ports over a wide bandwidth.

Evaluate Data Center Network Performance

DEFF Research Database (Denmark)

Pilimon, Artur

through a data center network, which is usually built with layer 2 switches and layer 3 routers. The topology of the data center network is crucial for latency in the data communication to and from the data center and between servers in the data center. Tests can be conducted to measure latency and other...... Engineering, scientists evaluate data center network topologies with an SDN-based (Software-Defined Networking) control framework measuring network performance – primarily latency. This can be used to plan data center scaling by testing how a new topology will function before changes are made. Data center...... performance parameters for different data center network topologies. It is however important that tests can be repeated and reproduced to have comparable information from the tests. There are, of course, many topologies that can be used for data center networks. At DTU Fotonik, Department of Photonics...

Multi-Criteria Vertical Handover Comparison between Wimax and Wifi

Directory of Open Access Journals (Sweden)

Maroua Drissi

2015-07-01

Full Text Available In next generation wireless networks, the most tempting feature is the ability of the user to move smoothly over different access networks regardless of the network access technology. In this paper we study the benefit of Multiple Attribute Decision Making (MADM strategies for network selection. We compare three of these methods naming Simple Additive Weighting (SAW, Multiplicative Exponential Weighting (MEW and Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS in a realtime ns-3 simulation. Analytic Hierarchy Process (AHP provides the weights of attributes which allow the comparison in different types of applications. Therefore, we propose a performance evaluation model with a reconfiguration of AHP parameters used in the literature. Simulation results show that the proposed parameters provide an improvement of Delay and offer allowable Packet loss in different types of applications.

Artificial Astrocytes Improve Neural Network Performance

Science.gov (United States)

Porto-Pazos, Ana B.; Veiguela, Noha; Mesejo, Pablo; Navarrete, Marta; Alvarellos, Alberto; Ibáñez, Oscar; Pazos, Alejandro; Araque, Alfonso

2011-01-01

Compelling evidence indicates the existence of bidirectional communication between astrocytes and neurons. Astrocytes, a type of glial cells classically considered to be passive supportive cells, have been recently demonstrated to be actively involved in the processing and regulation of synaptic information, suggesting that brain function arises from the activity of neuron-glia networks. However, the actual impact of astrocytes in neural network function is largely unknown and its application in artificial intelligence remains untested. We have investigated the consequences of including artificial astrocytes, which present the biologically defined properties involved in astrocyte-neuron communication, on artificial neural network performance. Using connectionist systems and evolutionary algorithms, we have compared the performance of artificial neural networks (NN) and artificial neuron-glia networks (NGN) to solve classification problems. We show that the degree of success of NGN is superior to NN. Analysis of performances of NN with different number of neurons or different architectures indicate that the effects of NGN cannot be accounted for an increased number of network elements, but rather they are specifically due to astrocytes. Furthermore, the relative efficacy of NGN vs. NN increases as the complexity of the network increases. These results indicate that artificial astrocytes improve neural network performance, and established the concept of Artificial Neuron-Glia Networks, which represents a novel concept in Artificial Intelligence with implications in computational science as well as in the understanding of brain function. PMID:21526157

Artificial astrocytes improve neural network performance.

Directory of Open Access Journals (Sweden)

Ana B Porto-Pazos

Full Text Available Compelling evidence indicates the existence of bidirectional communication between astrocytes and neurons. Astrocytes, a type of glial cells classically considered to be passive supportive cells, have been recently demonstrated to be actively involved in the processing and regulation of synaptic information, suggesting that brain function arises from the activity of neuron-glia networks. However, the actual impact of astrocytes in neural network function is largely unknown and its application in artificial intelligence remains untested. We have investigated the consequences of including artificial astrocytes, which present the biologically defined properties involved in astrocyte-neuron communication, on artificial neural network performance. Using connectionist systems and evolutionary algorithms, we have compared the performance of artificial neural networks (NN and artificial neuron-glia networks (NGN to solve classification problems. We show that the degree of success of NGN is superior to NN. Analysis of performances of NN with different number of neurons or different architectures indicate that the effects of NGN cannot be accounted for an increased number of network elements, but rather they are specifically due to astrocytes. Furthermore, the relative efficacy of NGN vs. NN increases as the complexity of the network increases. These results indicate that artificial astrocytes improve neural network performance, and established the concept of Artificial Neuron-Glia Networks, which represents a novel concept in Artificial Intelligence with implications in computational science as well as in the understanding of brain function.

Artificial astrocytes improve neural network performance.

Science.gov (United States)

Porto-Pazos, Ana B; Veiguela, Noha; Mesejo, Pablo; Navarrete, Marta; Alvarellos, Alberto; Ibáñez, Oscar; Pazos, Alejandro; Araque, Alfonso

2011-04-19

Compelling evidence indicates the existence of bidirectional communication between astrocytes and neurons. Astrocytes, a type of glial cells classically considered to be passive supportive cells, have been recently demonstrated to be actively involved in the processing and regulation of synaptic information, suggesting that brain function arises from the activity of neuron-glia networks. However, the actual impact of astrocytes in neural network function is largely unknown and its application in artificial intelligence remains untested. We have investigated the consequences of including artificial astrocytes, which present the biologically defined properties involved in astrocyte-neuron communication, on artificial neural network performance. Using connectionist systems and evolutionary algorithms, we have compared the performance of artificial neural networks (NN) and artificial neuron-glia networks (NGN) to solve classification problems. We show that the degree of success of NGN is superior to NN. Analysis of performances of NN with different number of neurons or different architectures indicate that the effects of NGN cannot be accounted for an increased number of network elements, but rather they are specifically due to astrocytes. Furthermore, the relative efficacy of NGN vs. NN increases as the complexity of the network increases. These results indicate that artificial astrocytes improve neural network performance, and established the concept of Artificial Neuron-Glia Networks, which represents a novel concept in Artificial Intelligence with implications in computational science as well as in the understanding of brain function.

Performance modeling of network data services

Energy Technology Data Exchange (ETDEWEB)

Haynes, R.A.; Pierson, L.G.

1997-01-01

Networks at major computational organizations are becoming increasingly complex. The introduction of large massively parallel computers and supercomputers with gigabyte memories are requiring greater and greater bandwidth for network data transfers to widely dispersed clients. For networks to provide adequate data transfer services to high performance computers and remote users connected to them, the networking components must be optimized from a combination of internal and external performance criteria. This paper describes research done at Sandia National Laboratories to model network data services and to visualize the flow of data from source to sink when using the data services.

Cross Deployment Networking and Systematic Performance Analysis of Underwater Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Zhengxian Wei

2017-07-01

Full Text Available Underwater wireless sensor networks (UWSNs have become a new hot research area. However, due to the work dynamics and harsh ocean environment, how to obtain an UWSN with the best systematic performance while deploying as few sensor nodes as possible and setting up self-adaptive networking is an urgent problem that needs to be solved. Consequently, sensor deployment, networking, and performance calculation of UWSNs are challenging issues, hence the study in this paper centers on this topic and three relevant methods and models are put forward. Firstly, the normal body-centered cubic lattice to cross body-centered cubic lattice (CBCL has been improved, and a deployment process and topology generation method are built. Then most importantly, a cross deployment networking method (CDNM for UWSNs suitable for the underwater environment is proposed. Furthermore, a systematic quar-performance calculation model (SQPCM is proposed from an integrated perspective, in which the systematic performance of a UWSN includes coverage, connectivity, durability and rapid-reactivity. Besides, measurement models are established based on the relationship between systematic performance and influencing parameters. Finally, the influencing parameters are divided into three types, namely, constraint parameters, device performance and networking parameters. Based on these, a networking parameters adjustment method (NPAM for optimized systematic performance of UWSNs has been presented. The simulation results demonstrate that the approach proposed in this paper is feasible and efficient in networking and performance calculation of UWSNs.

Wireless networked music performance

CERN Document Server

Gabrielli, Leonardo

2016-01-01

This book presents a comprehensive overview of the state of the art in Networked Music Performance (NMP) and a historical survey of computer music networking. It introduces current technical trends in NMP and technical issues yet to be addressed. It also lists wireless communication protocols and compares these to the requirements of NMP. Practical use cases and advancements are also discussed.

The promise of downlink MU-MIMO for high-capacity next generation mobile broadband networks based on IEEE 802.16 m

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Papathanassiou Apostolos

2011-01-01

Full Text Available Abstract The dramatic increase of the demand for mobile broadband services poses stringent requirements on the performance evolution of currently deployed mobile broadband networks, such as Mobile WiMAX Release 1 and 3GPP LTE Release 8. Although the combination of single-user multiple-input multiple-output (SU-MIMO and orthogonal frequency division multiple access (OFDMA provide the appropriate technologies for improving the downlink performance of third generation (3G code division multiple access (CDMA-based mobile radio systems and, thus, address the current mobile internet requirements, a fundamental paradigm shift is required to cope with the constantly increasing mobile broadband data rate and spectral efficiency requirements. Among the different technologies available for making the paradigm shift from current to next-generation mobile broadband networks, multiuser MIMO (MU-MIMO constitutes the most promising technology because of its significant performance improvement advantages. In this article, we analyze the performance of MU-MIMO under a multitude of deployment scenarios and system parameters through extensive system-level simulations which are based on widely used system-level evaluation methodologies. The target mobile broadband system used in the simulations is IEEE 802.16 m which was recently adopted by ITU-R as an IMT-Advanced technology along with 3GPP LTE-Advanced. The results provide insights into different aspects of MU-MIMO with respect to system-level performance, parameter sensitivity, and deployment scenarios, and they can be used by the mobile broadband network designer for maximizing the benefits of MU-MIMO in a scenario with specific deployment requirements and goals.

Performance Evaluation Of Mobile Cellular Networks In Nigeria

OpenAIRE

Shoewu, O.O

2018-01-01

The aim of this paper is to evaluate the performance of mobile networks such as MTN, GLO, and ETISALAT in Nigeria and suggest ways the performance of digital cellular networks can improve to minimize some of its present short comings or limitations. This paper discusses the performance improvement of digital cellular networks. A non- CDMA cellular network is use in an overall wireless environment for the purpose of this paper. This paper also discusses the performance assessment of three mobi...

ANÁLISIS DE DESEMPEÑO DE CALIDAD DE SERVICIO SOBRE REDES INALÁMBRICAS BASADAS EN TECNOLOGÍA WIMAX

Directory of Open Access Journals (Sweden)

Ruben Dario Gomez Tovar

2012-05-01

Full Text Available Actualmente el uso de redes inalámbricas se encuentra en un punto de alta demanda, debido a su flexibilidad y bajos costos en la implementación de las mismas. A  partir de la construcción de la norma IEEE 802.16 (WiMAX  y de las necesidades actuales en campos médicos, educativos, entre otros por acceder a la información y en general por poder establecer comunicaciones confiables se permite que la industria y los centros de investigación fortalezcan la implementación de estas tecnologías.Para satisfacer estas necesidades se hace importante garantizar un servicio que cumpla con los requerimientos solicitados, en este orden de ideas es importante, analizar el funcionamiento de este tipo de tecnologías a través de la evaluación del desempeño incluyendo parámetros de calidad de servicio (QoS basados en la norma IEEE 802.16.

Network performance for graphical control systems

International Nuclear Information System (INIS)

Clout, P.; Geib, M.; Westervelt, R.

1992-01-01

Vsystem is a toolbox for building graphically-based control systems. The real-tiem database component, Vaccess, includes all the networking support necessary to build multi-computer control systems. Vaccess has two modes of database access, synchronous and asynchronous. Vdraw is another component of Vsystem that allows developers and users to develop control screens and windows by drawing rather than programming. Based on X-windows, Vsystem provides the possibility of running Vdraw either on the workstation with the graphics or on the computer with the database. We have made some measurements on the cpu loading, elapsed time and the network loading to give some guidance in system configuration performance. It will be seen that asynchronous network access gives large performance increases and that the network database change notification protocol can be either more or less efficient than the X-window network protocol, depending on the graphical representation of the data. (author)

Virtual Networking Performance in OpenStack Platform for Network Function Virtualization

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Franco Callegati

2016-01-01

Full Text Available The emerging Network Function Virtualization (NFV paradigm, coupled with the highly flexible and programmatic control of network devices offered by Software Defined Networking solutions, enables unprecedented levels of network virtualization that will definitely change the shape of future network architectures, where legacy telco central offices will be replaced by cloud data centers located at the edge. On the one hand, this software-centric evolution of telecommunications will allow network operators to take advantage of the increased flexibility and reduced deployment costs typical of cloud computing. On the other hand, it will pose a number of challenges in terms of virtual network performance and customer isolation. This paper intends to provide some insights on how an open-source cloud computing platform such as OpenStack implements multitenant network virtualization and how it can be used to deploy NFV, focusing in particular on packet forwarding performance issues. To this purpose, a set of experiments is presented that refer to a number of scenarios inspired by the cloud computing and NFV paradigms, considering both single tenant and multitenant scenarios. From the results of the evaluation it is possible to highlight potentials and limitations of running NFV on OpenStack.

Topology influences performance in the associative memory neural networks

International Nuclear Information System (INIS)

Lu Jianquan; He Juan; Cao Jinde; Gao Zhiqiang

2006-01-01

To explore how topology affects performance within Hopfield-type associative memory neural networks (AMNNs), we studied the computational performance of the neural networks with regular lattice, random, small-world, and scale-free structures. In this Letter, we found that the memory performance of neural networks obtained through asynchronous updating from 'larger' nodes to 'smaller' nodes are better than asynchronous updating in random order, especially for the scale-free topology. The computational performance of associative memory neural networks linked by the above-mentioned network topologies with the same amounts of nodes (neurons) and edges (synapses) were studied respectively. Along with topologies becoming more random and less locally disordered, we will see that the performance of associative memory neural network is quite improved. By comparing, we show that the regular lattice and random network form two extremes in terms of patterns stability and retrievability. For a network, its patterns stability and retrievability can be largely enhanced by adding a random component or some shortcuts to its structured component. According to the conclusions of this Letter, we can design the associative memory neural networks with high performance and minimal interconnect requirements

Diversity Performance Analysis on Multiple HAP Networks

Science.gov (United States)

Dong, Feihong; Li, Min; Gong, Xiangwu; Li, Hongjun; Gao, Fengyue

2015-01-01

One of the main design challenges in wireless sensor networks (WSNs) is achieving a high-data-rate transmission for individual sensor devices. The high altitude platform (HAP) is an important communication relay platform for WSNs and next-generation wireless networks. Multiple-input multiple-output (MIMO) techniques provide the diversity and multiplexing gain, which can improve the network performance effectively. In this paper, a virtual MIMO (V-MIMO) model is proposed by networking multiple HAPs with the concept of multiple assets in view (MAV). In a shadowed Rician fading channel, the diversity performance is investigated. The probability density function (PDF) and cumulative distribution function (CDF) of the received signal-to-noise ratio (SNR) are derived. In addition, the average symbol error rate (ASER) with BPSK and QPSK is given for the V-MIMO model. The system capacity is studied for both perfect channel state information (CSI) and unknown CSI individually. The ergodic capacity with various SNR and Rician factors for different network configurations is also analyzed. The simulation results validate the effectiveness of the performance analysis. It is shown that the performance of the HAPs network in WSNs can be significantly improved by utilizing the MAV to achieve overlapping coverage, with the help of the V-MIMO techniques. PMID:26134102

Diversity Performance Analysis on Multiple HAP Networks

Directory of Open Access Journals (Sweden)

Feihong Dong

2015-06-01

Full Text Available One of the main design challenges in wireless sensor networks (WSNs is achieving a high-data-rate transmission for individual sensor devices. The high altitude platform (HAP is an important communication relay platform for WSNs and next-generation wireless networks. Multiple-input multiple-output (MIMO techniques provide the diversity and multiplexing gain, which can improve the network performance effectively. In this paper, a virtual MIMO (V-MIMO model is proposed by networking multiple HAPs with the concept of multiple assets in view (MAV. In a shadowed Rician fading channel, the diversity performance is investigated. The probability density function (PDF and cumulative distribution function (CDF of the received signal-to-noise ratio (SNR are derived. In addition, the average symbol error rate (ASER with BPSK and QPSK is given for the V-MIMO model. The system capacity is studied for both perfect channel state information (CSI and unknown CSI individually. The ergodic capacity with various SNR and Rician factors for different network configurations is also analyzed. The simulation results validate the effectiveness of the performance analysis. It is shown that the performance of the HAPs network in WSNs can be significantly improved by utilizing the MAV to achieve overlapping coverage, with the help of the V-MIMO techniques.

Building and measuring a high performance network architecture

Energy Technology Data Exchange (ETDEWEB)

Kramer, William T.C.; Toole, Timothy; Fisher, Chuck; Dugan, Jon; Wheeler, David; Wing, William R; Nickless, William; Goddard, Gregory; Corbato, Steven; Love, E. Paul; Daspit, Paul; Edwards, Hal; Mercer, Linden; Koester, David; Decina, Basil; Dart, Eli; Paul Reisinger, Paul; Kurihara, Riki; Zekauskas, Matthew J; Plesset, Eric; Wulf, Julie; Luce, Douglas; Rogers, James; Duncan, Rex; Mauth, Jeffery

2001-04-20

Once a year, the SC conferences present a unique opportunity to create and build one of the most complex and highest performance networks in the world. At SC2000, large-scale and complex local and wide area networking connections were demonstrated, including large-scale distributed applications running on different architectures. This project was designed to use the unique opportunity presented at SC2000 to create a testbed network environment and then use that network to demonstrate and evaluate high performance computational and communication applications. This testbed was designed to incorporate many interoperable systems and services and was designed for measurement from the very beginning. The end results were key insights into how to use novel, high performance networking technologies and to accumulate measurements that will give insights into the networks of the future.

Performance Monitoring Techniques Supporting Cognitive Optical Networking

DEFF Research Database (Denmark)

Caballero Jambrina, Antonio; Borkowski, Robert; Zibar, Darko

2013-01-01

High degree of heterogeneity of future optical networks, such as services with different quality-of-transmission requirements, modulation formats and switching techniques, will pose a challenge for the control and optimization of different parameters. Incorporation of cognitive techniques can help...... to solve this issue by realizing a network that can observe, act, learn and optimize its performance, taking into account end-to-end goals. In this letter we present the approach of cognition applied to heterogeneous optical networks developed in the framework of the EU project CHRON: Cognitive...... Heterogeneous Reconfigurable Optical Network. We focus on the approaches developed in the project for optical performance monitoring, which enable the feedback from the physical layer to the cognitive decision system by providing accurate description of the performance of the established lightpaths....

Optical Networks Solutions planning - performances - management

DEFF Research Database (Denmark)

Fenger, Christian

2002-01-01

It has been a decisive goal in the compilation of this thesis to make us capable of realizing the future national and regional telecommunication networks in an efficient and resource optimal way. By future telecommunication network is assumed an all optical network where the information in transit...... are kept optical and not converted into the optical domain. The focus is on the scientific results achieved throughout the Ph.D. period. Five subjects – all increasing the understanding of optical networks – are studied. Static wavelength routed optical networks are studied. Management on terms...... of lightpath allocation and design is considered. By using statistical models (simultaneous analysis of many networks) the correspondence between parameters determining the network topology and the performance of the optical network is found. These dependencies are important knowledge in the process...

Optical interconnection networks for high-performance computing systems

International Nuclear Information System (INIS)

Biberman, Aleksandr; Bergman, Keren

2012-01-01

Enabled by silicon photonic technology, optical interconnection networks have the potential to be a key disruptive technology in computing and communication industries. The enduring pursuit of performance gains in computing, combined with stringent power constraints, has fostered the ever-growing computational parallelism associated with chip multiprocessors, memory systems, high-performance computing systems and data centers. Sustaining these parallelism growths introduces unique challenges for on- and off-chip communications, shifting the focus toward novel and fundamentally different communication approaches. Chip-scale photonic interconnection networks, enabled by high-performance silicon photonic devices, offer unprecedented bandwidth scalability with reduced power consumption. We demonstrate that the silicon photonic platforms have already produced all the high-performance photonic devices required to realize these types of networks. Through extensive empirical characterization in much of our work, we demonstrate such feasibility of waveguides, modulators, switches and photodetectors. We also demonstrate systems that simultaneously combine many functionalities to achieve more complex building blocks. We propose novel silicon photonic devices, subsystems, network topologies and architectures to enable unprecedented performance of these photonic interconnection networks. Furthermore, the advantages of photonic interconnection networks extend far beyond the chip, offering advanced communication environments for memory systems, high-performance computing systems, and data centers. (review article)

Experimental performance evaluation of software defined networking (SDN) based data communication networks for large scale flexi-grid optical networks.

Science.gov (United States)

Zhao, Yongli; He, Ruiying; Chen, Haoran; Zhang, Jie; Ji, Yuefeng; Zheng, Haomian; Lin, Yi; Wang, Xinbo

2014-04-21

Software defined networking (SDN) has become the focus in the current information and communication technology area because of its flexibility and programmability. It has been introduced into various network scenarios, such as datacenter networks, carrier networks, and wireless networks. Optical transport network is also regarded as an important application scenario for SDN, which is adopted as the enabling technology of data communication networks (DCN) instead of general multi-protocol label switching (GMPLS). However, the practical performance of SDN based DCN for large scale optical networks, which is very important for the technology selection in the future optical network deployment, has not been evaluated up to now. In this paper we have built a large scale flexi-grid optical network testbed with 1000 virtual optical transport nodes to evaluate the performance of SDN based DCN, including network scalability, DCN bandwidth limitation, and restoration time. A series of network performance parameters including blocking probability, bandwidth utilization, average lightpath provisioning time, and failure restoration time have been demonstrated under various network environments, such as with different traffic loads and different DCN bandwidths. The demonstration in this work can be taken as a proof for the future network deployment.

Performance testing framework for smart grid communication network

International Nuclear Information System (INIS)

Quang, D N; See, O H; Chee, L L; Xuen, C Y; Karuppiah, S

2013-01-01

Smart grid communication network is comprised of different communication mediums and technologies. Performance evaluation is one of the main concerns in smart grid communication system. In any smart grid communication implementation, to determine the performance factor of the network, a testing of an end-to-end process flow is required. Therefore, an effective and coordinated testing procedure plays a crucial role in evaluating the performance of smart grid communications. In this paper, a testing framework is proposed as a guideline to analyze and assess the performance of smart grid communication network.

Academic Performance and the Use of Social Networks

Directory of Open Access Journals (Sweden)

Jéssica Ribeiro Rangel

2016-08-01

Full Text Available This study aimed to investigate whether the use of social networks influences on the academic performance of students in the undergraduate program in accounting. Data were collected from 322 students of the course of a federal University of the State of Minas Gerais, Brazil. The regression results show that the variables "gender", "motivation" and "classification in the University entrance examination" are significant in explaining students' academic performance measured by the Grade Point Average (GPA. The results show that the performance of male students is lower than that of female students at the level of 5%. Also was identified that the greater the student's motivation level, the greater your academic performance (at the level of 1 percent. Finally, it was observed that the best ranked students in the University entrance examination, the higher their academic performance. However, none of the variables relating to the use of social networks ("familiarity with technological resources", "hours", "Internet hours on social networks" and "use of social networks to study" presented relation with academic performance. In other words, these results show that the use of social networks does not have positive or negative impacts directly on academic performance. We can conclude for the sample analyzed, that use of social networks during the academic period does not influence significantly the performance of the students. However, you can verify that the motivation is directly related to the academic performance of the Accounting student with regard to perception of motivation, to familiarity with technological resources and the use of applications.

Social Networking and Academic Performance: A Review

Science.gov (United States)

Doleck, Tenzin; Lajoie, Susanne

2018-01-01

The ubiquitous use of social networking sites by students and the potential impacts of such use on academic performance are of both theoretical and practical importance. Hence, this paper addresses the question: how does the use of social networking sites influence academic performance? The present review synthesizes the empirical findings of the…

The Homogeneity Research of Urban Rail Transit Network Performance

Directory of Open Access Journals (Sweden)

Wang Fu-jian

2016-01-01

Full Text Available Urban Rail Transit is an important part of the public transit, it is necessary to carry out the corresponding network function analysis. Previous studies mainly about network performance analysis of a single city rail transit, lacking of horizontal comparison between the multi-city, it is difficult to find inner unity of different Urban Rail Transit network functions. Taking into account the Urban Rail Transit network is a typical complex networks, so this paper proposes the application of complex network theory to research the homogeneity of Urban Rail Transit network performance. This paper selects rail networks of Beijing, Shanghai, Guangzhou as calculation case, gave them a complex network mapping through the L, P Space method and had a static topological analysis using complex network theory, Network characteristics in three cities were calculated and analyzed form node degree distribution and node connection preference. Finally, this paper studied the network efficiency changes of Urban Rail Transit system under different attack mode. The results showed that, although rail transport network size, model construction and construction planning of the three cities are different, but their network performance in many aspects showed high homogeneity.

In-Network Performance of Handheld Mobile Terminals

DEFF Research Database (Denmark)

Nielsen, Jesper Ødum; Pedersen, Gert Frølund

2006-01-01

are compared with the equivalent performance obtained in a live GSM network using data from the Abis network interface. This method does not require altering of the handsets and the testing uses normal calls in the network. The investigation is based on measurements with four different commercially available...

Secure and Efficient Data Transmission over Body Sensor and Wireless Networks

Directory of Open Access Journals (Sweden)

Madhur Sikri

2008-09-01

Full Text Available This paper addresses the transmission of medical and context-aware data from mobile patients to healthcare centers over heterogeneous wireless networks. A handheld device, called personal wireless hub (PWH, of each mobile patient first gathers and aggregates the vital sign and context-aware data for various telemedicine applications. PWH transmits the aggregated data to the remote healthcare center over multiple wireless interfaces such as cellular, WLAN, and WiMAX. The aggregated data contain both periodic data and those nonperiodic unpredictable emergency messages that are sporadic and delayintolerant. This paper addresses the problem of providing QoS (e.g., minimum delay, sufficient data rate, acceptable blocking, and/or dropping rate by designing a packet scheduling and channel/network allocation algorithm over wireless networks. The proposed resource-efficient QoS mechanism is simple and collaborates with an adaptive security algorithm. The QoS and security are achieved mainly with the collaboration of differentiator, delay monitor, data classifier, and scheduler modules within the PWH. This paper also discusses secure data transmission over body sensor networks by introducing key establishment and management algorithms. Simulation results show that the proposed framework achieves low-blocking probability, meets delay requirements, and provides energy-efficient secure communication for the combination of vital signs and context-aware data.

Secure and Efficient Data Transmission over Body Sensor and Wireless Networks

Directory of Open Access Journals (Sweden)

Challa Narasimha

2008-01-01

Full Text Available Abstract This paper addresses the transmission of medical and context-aware data from mobile patients to healthcare centers over heterogeneous wireless networks. A handheld device, called personal wireless hub (PWH, of each mobile patient first gathers and aggregates the vital sign and context-aware data for various telemedicine applications. PWH transmits the aggregated data to the remote healthcare center over multiple wireless interfaces such as cellular, WLAN, and WiMAX. The aggregated data contain both periodic data and those nonperiodic unpredictable emergency messages that are sporadic and delayintolerant. This paper addresses the problem of providing QoS (e.g., minimum delay, sufficient data rate, acceptable blocking, and/or dropping rate by designing a packet scheduling and channel/network allocation algorithm over wireless networks. The proposed resource-efficient QoS mechanism is simple and collaborates with an adaptive security algorithm. The QoS and security are achieved mainly with the collaboration of differentiator, delay monitor, data classifier, and scheduler modules within the PWH. This paper also discusses secure data transmission over body sensor networks by introducing key establishment and management algorithms. Simulation results show that the proposed framework achieves low-blocking probability, meets delay requirements, and provides energy-efficient secure communication for the combination of vital signs and context-aware data.

Network performance of a wireless sensor network for temperature monitoring in vineyards

DEFF Research Database (Denmark)

Liscano, Ramiro; Jacoub, John Khalil; Dersingh, Anand

2011-01-01

Wireless sensor networks (WSNs) are an emerging technology which can be used for outdoor environmental monitoring. This paper presents challenges that arose from the development and deployment of a WSN for environmental monitoring as well as network performance analysis of this network. Different...... components in our sensor network architecture are presented like the physical nodes, the sensor node code, and two messaging protocols; one for collecting sensor and network values and the other for sensor node commands. An information model for sensor nodes to support plug-and-play capabilities in sensor...... networks is also presented....

Structure of Small World Innovation Network and Learning Performance

Directory of Open Access Journals (Sweden)

Shuang Song

2014-01-01

Full Text Available This paper examines the differences of learning performance of 5 MNCs (multinational corporations that filed the largest number of patents in China. We establish the innovation network with the patent coauthorship data by these 5 MNCs and classify the networks by the tail of distribution curve of connections. To make a comparison of the learning performance of these 5 MNCs with differing network structures, we develop an organization learning model by regarding the reality as having m dimensions, which denotes the heterogeneous knowledge about the reality. We further set n innovative individuals that are mutually interactive and own unique knowledge about the reality. A longer (shorter distance between the knowledge of the individual and the reality denotes a lower (higher knowledge level of that individual. Individuals interact with and learn from each other within the small-world network. By making 1,000 numerical simulations and averaging the simulated results, we find that the differing structure of the small-world network leads to the differences of learning performance between these 5 MNCs. The network monopolization negatively impacts and network connectivity positively impacts learning performance. Policy implications in the conclusion section suggest that to improve firm learning performance, it is necessary to establish a flat and connective network.

Scholastic performance and functional connectivity of brain networks in children.

Directory of Open Access Journals (Sweden)

Laura Chaddock-Heyman

Full Text Available One of the keys to understanding scholastic success is to determine the neural processes involved in school performance. The present study is the first to use a whole-brain connectivity approach to explore whether functional connectivity of resting state brain networks is associated with scholastic performance in seventy-four 7- to 9-year-old children. We demonstrate that children with higher scholastic performance across reading, math and language have more integrated and interconnected resting state networks, specifically the default mode network, salience network, and frontoparietal network. To add specificity, core regions of the dorsal attention and visual networks did not relate to scholastic performance. The results extend the cognitive role of brain networks in children as well as suggest the importance of network connectivity in scholastic success.

Enhancing neural-network performance via assortativity

International Nuclear Information System (INIS)

Franciscis, Sebastiano de; Johnson, Samuel; Torres, Joaquin J.

2011-01-01

The performance of attractor neural networks has been shown to depend crucially on the heterogeneity of the underlying topology. We take this analysis a step further by examining the effect of degree-degree correlations - assortativity - on neural-network behavior. We make use of a method recently put forward for studying correlated networks and dynamics thereon, both analytically and computationally, which is independent of how the topology may have evolved. We show how the robustness to noise is greatly enhanced in assortative (positively correlated) neural networks, especially if it is the hub neurons that store the information.

Networks, Micro Small Enterprises (MSE'S) and Performance: the ...

African Journals Online (AJOL)

Networks, Micro Small Enterprises (MSE'S) and Performance: the Case of Kenya. ... It adopts the network perspective theoretical approach. Empirically, the ... entrepreneurial personal network as a copying strategy in the process of global

Impact Of Firewall On Network Performance

Directory of Open Access Journals (Sweden)

Francis Kwadzo Agbenyegah

2017-03-01

Full Text Available This research work investigated the firewall security and performance relationship for distributed systems. Internet connectivity is growing with most enterprises migrating to the use of web based services for services provision. As organization grab the Internet as another business tool whether to sell to team up or to communicate - web applications have turned into the new weakest connection in the organizations security technique. Firewalls provide a mechanism for protecting these enterprises from the less secure internet over which customers or collaborating partners transfer packets destined for the corporate network. The connection between the security and execution proficiency is exhibited through distinctive scenarios and the relationship between security and performance in firewalls is assessed. We demonstrated distinctive networks with and without firewalls and diverse firewall functionality and simulated such systems with an eye on their performance. The simulation was done for 300 work stations and simulated in a way that all the 300 work stations access an email and web application under three different scenarios. Attention is on the relationship between system security and performance the impacts of firewalls on system execution. Different scenarios were assessed through simulations utilizing OPNET IT Guru Academic Edition 9.1 to demonstrate the impacts of firewalls on system performance. The result shows that maintaining security which involves the utilization of numerous applications and the use of firewall has an effect on network performance.

Network Signaling Channel for Improving ZigBee Performance in Dynamic Cluster-Tree Networks

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D. Hämäläinen

2008-03-01

Full Text Available ZigBee is one of the most potential standardized technologies for wireless sensor networks (WSNs. Yet, sufficient energy-efficiency for the lowest power WSNs is achieved only in rather static networks. This severely limits the applicability of ZigBee in outdoor and mobile applications, where operation environment is harsh and link failures are common. This paper proposes a network channel beaconing (NCB algorithm for improving ZigBee performance in dynamic cluster-tree networks. NCB reduces the energy consumption of passive scans by dedicating one frequency channel for network beacon transmissions and by energy optimizing their transmission rate. According to an energy analysis, the power consumption of network maintenance operations reduces by 70%–76% in dynamic networks. In static networks, energy overhead is negligible. Moreover, the service time for data routing increases up to 37%. The performance of NCB is validated by ns-2 simulations. NCB can be implemented as an extension on MAC and NWK layers and it is fully compatible with ZigBee.

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.

Wireless Local Area Network Performance Inside Aircraft Passenger Cabins

Science.gov (United States)

Whetten, Frank L.; Soroker, Andrew; Whetten, Dennis A.; Whetten, Frank L.; Beggs, John H.

2005-01-01

An examination of IEEE 802.11 wireless network performance within an aircraft fuselage is performed. This examination measured the propagated RF power along the length of the fuselage, and the associated network performance: the link speed, total throughput, and packet losses and errors. A total of four airplanes: one single-aisle and three twin-aisle airplanes were tested with 802.11a, 802.11b, and 802.11g networks.

Ethernet image communication performance in a multimodal PACS network

International Nuclear Information System (INIS)

Lou, S.L.; Valentino, D.J.; Chan, K.K.; Huang, H.K.

1989-01-01

The authors have evaluated the performance of an Ethernet network in a multimodal picture archiving and communications system (PACS) environment. The study included measurements between Sun workstations and PC- AT computers running communication software at the TCP level. First they initiated image transfers between two workstations, a server and a client. Next, they successively added clients to transfer images to the server and they measured degradation in network performance. Finally, they initiated image transfers between pairs of workstations and again measured performance degradation. The results of the authors' experiments indicate that Ethernet is suitable for image communication only in limited network situations. They discuss how to maximize network performance given these constraints

Coexistencia e integracion de comunicaciones inalambricas en sistemas de transmision opticos

Science.gov (United States)

Perez Soler, Joaquin

protection margins in order to ensure the coexistence between both technologies. The obtained protection margins are of great interest for the development of advanced interference mitigation techniques such as DAA (Detect-and-Avoid), in the framework of future cognitive radio technologies. In a second step, the wireless coexistence of MB-OFDM UWB and WiMAX technologies is analyzed from the point of view of access networks based on RoF systems. Two experimental field trials are here carried out. In the first one, the wireless convergence is evaluated in a multi-mode fibre RoF system, whereas in the second one, the RoF system is based on a standard single-mode fibre. These experimental results provide relevant fibre link transmission distances to enable the deployment of RoF networks. Moreover, a new optical transmission technique based on polarization division multiplexing is proposed and experimentally evaluated in order to ensure the wireless coexistence in RoF systems. Finally, the impact of the electro-optical Mach-Zehnder modulator is analyzed, since the dynamic range of this device limits the performance of the RoF system. Moreover, a new optical linearization technique for Mach-Zehnder modulators is proposed and evaluated in order to overcome this limitation.

Design and Co-simulation of Hierarchical Architecture for Demand Response Control and Coordination

DEFF Research Database (Denmark)

Bhattarai, Bishnu Prasad; Lévesque, Martin; Bak-Jensen, Birgitte

2017-01-01

and coordinate the performance of various DR categories such that the operation of every DR category is backed-up by time delayed action of the others. A reliable, cost-effective communication infrastructure based on ZigBee, WiMAX, and fibers is designed to facilitate the HDRA execution. The performance...... of the proposed HDRA is demonstrated from the power system and communication perspectives in a co-simulation environment applied to a 0.4 kV/400 kVA real distribution network considering electric vehicles as a potential DR resource. The power simulation is performed employing a real time digital simulator (RTDS...

Building a sustainable research & HCD eco-system: Case study of two wireless communication eco systems

CSIR Research Space (South Africa)

Mekuria, F

2013-05-01

Full Text Available Sensor Networks (M2M, Energy Efficient & Smart Adhoc Sensor Networks) (Emerging) Energy & Spectrum Efficient Wireless Mesh Network (Existing) Next Generation Wireless Networking (e.g. White Spaces, Femto-cells, Cellular ± 4G, LTE, WiMAX) (Co... applications, M2M and the Internet of Things, (3) wireless cognitive radio network laboratory for spectrum and energy efficient network development, (4) Future wireless cellular networking research with MIMO based LTE applications. The wireless mesh...

Performance of networks of artificial neurons: The role of clustering

International Nuclear Information System (INIS)

Kim, Beom Jun

2004-01-01

The performance of the Hopfield neural network model is numerically studied on various complex networks, such as the Watts-Strogatz network, the Barabasi-Albert network, and the neuronal network of Caenorhabditis elegans. Through the use of a systematic way of controlling the clustering coefficient, with the degree of each neuron kept unchanged, we find that the networks with the lower clustering exhibit much better performance. The results are discussed in the practical viewpoint of application, and the biological implications are also suggested

Force10 networks performance in world's first transcontinental 10 gigabit ethernet network verified by Ixia

CERN Multimedia

2003-01-01

Force10 Networks, Inc., today announced that the performance of the Force10 E-Series switch/routers deployed in a transcontinental network has been verified as line-rate 10 GE throughput by Ixia, a leading provider of high-speed, network performance and conformance analysis systems. The network, the world's first transcontinental 10 GE wide area network, consists of a SURFnet OC-192 lambda between Geneva and the StarLight facility in Chicago via Amsterdam and another OC-192 lambda between this same facility in Chicago and Carleton University in Ottawa, Canada provided by CANARIE and ORANO (1/2 page).

Network performance and fault analytics for LTE wireless service providers

CERN Document Server

Kakadia, Deepak; Gilgur, Alexander

2017-01-01

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

Hamlet, Performance and Chaotic Cultural Networks

Directory of Open Access Journals (Sweden)

Emil Rybczak

2015-10-01

Full Text Available Since the 1960s, chaos theory has become an important but controversial tool used by scientists and mathematicians to describe physical or theoretical systems or networks. It explains how the simple can generate the complex. Its central tenets can also provide an alternative language and means of literary interpretation. This article will explore how the principles of chaos theory can be used to close read and systematise various aspects of the language and performance of Shakespeare. The argument is built upon an analysis of Hamlet, in an effort to understand the play and its reproduction as the evolution of interconnected complex networks. Various aspects of the text will be discussed, including its language, structural and character patterning, and its reproduction through performance and cinematic adaptation. Each of these topics, and the characters, devices or ideas they discuss, constitute nodes of the complex network of Hamlet as both text and idea. Responding to the cultural analysis of other scholars, this article uses Hamlet as an ideal example of how the appropriation of scientific language can defamiliarise a particular literary or dramatic artefact. This allows fresh interpretation and understanding of its location within the broader networks of theatre and culture. I suggest the possibilities of close reading literary works through the lens of chaos and suggest how they might be applied and developed in conjunction with other texts, media or performances.

Performance Analysis of IIUM Wireless Campus Network

International Nuclear Information System (INIS)

Latif, Suhaimi Abd; Masud, Mosharrof H; Anwar, Farhat

2013-01-01

International Islamic University Malaysia (IIUM) is one of the leading universities in the world in terms of quality of education that has been achieved due to providing numerous facilities including wireless services to every enrolled student. The quality of this wireless service is controlled and monitored by Information Technology Division (ITD), an ISO standardized organization under the university. This paper aims to investigate the constraints of wireless campus network of IIUM. It evaluates the performance of the IIUM wireless campus network in terms of delay, throughput and jitter. QualNet 5.2 simulator tool has employed to measure these performances of IIUM wireless campus network. The observation from the simulation result could be one of the influencing factors in improving wireless services for ITD and further improvement

Multiplex network analysis of employee performance and employee social relationships

Science.gov (United States)

Cai, Meng; Wang, Wei; Cui, Ying; Stanley, H. Eugene

2018-01-01

In human resource management, employee performance is strongly affected by both formal and informal employee networks. Most previous research on employee performance has focused on monolayer networks that can represent only single categories of employee social relationships. We study employee performance by taking into account the entire multiplex structure of underlying employee social networks. We collect three datasets consisting of five different employee relationship categories in three firms, and predict employee performance using degree centrality and eigenvector centrality in a superimposed multiplex network (SMN) and an unfolded multiplex network (UMN). We use a quadratic assignment procedure (QAP) analysis and a regression analysis to demonstrate that the different categories of relationship are mutually embedded and that the strength of their impact on employee performance differs. We also use weighted/unweighted SMN/UMN to measure the predictive accuracy of this approach and find that employees with high centrality in a weighted UMN are more likely to perform well. Our results shed new light on how social structures affect employee performance.

Enhanced Seamless Handover Algorithm for WiMAX and LTE Roaming

Directory of Open Access Journals (Sweden)

HINDIA, M. N.

2014-11-01

Full Text Available With the ever evolving mobile communication technology, achieving a high quality seamless mobility access across mobile networks is the present challenge to research and development engineers. Existing algorithms are used to make handover while a mobile station is roaming between cells. Such algorithms have some handover instability due to method of making handover decision. This paper proposes an enhanced handover algorithm that substantially reduces the handover redundancy in vertical and horizontal handovers. Also, it enables users to select the most appropriate target network technology based on their preferences even in the worst case where the mobile station roams between cell boundaries, and has high ability to have efficient performance in the critical area full of interferences. The proposed algorithm uses additional quality of service criteria, such as cost, delay, available bandwidth and network condition with two handover thresholds to achieve a better seamless handover process. After developing and testing this algorithm, the simulation results show a major reduction in the redundant handover, so high accuracy of horizontal and vertical handovers obtained. Moreover, the signal strength is kept at a level higher than the threshold during the whole simulation period, while maintaining low delay and connection cost compared to other two algorithms in both scenarios.

Analysis of interference performance of tactical radio network

Science.gov (United States)

Nie, Hao; Cai, Xiaoxia; Chen, Hong

2017-08-01

Mobile Ad hoc network has a strong military background for its development as the core technology of the backbone network of US tactical Internet. And which tactical radio network, is the war in today's tactical use of the Internet more mature form of networking, mainly used in brigade and brigade following forces. This paper analyzes the typical protocol AODV in the tactical radio network, and then carries on the networking. By adding the interference device to the whole network, the battlefield environment is simulated, and then the throughput, delay and packet loss rate are analyzed, and the performance of the whole network and the single node before and after the interference is obtained.

Modeling the Effect of Bandwidth Allocation on Network Performance

African Journals Online (AJOL)

... The proposed model showed improved performance for CDMA networks, but further increase in the bandwidth did not benefit the network; (iii) A reliability measure such as the spectral efficiency is therefore useful to redeem the limitation in (ii). Keywords: Coverage Capacity, CDMA, Mobile Network, Network Throughput ...

User-Location Aware Downlink Performance Analysis of LTE Networks

OpenAIRE

Olaifa, John Olorunfemi

2016-01-01

In order to evaluate the performance of Long Term Evolution (LTE) networks, system-level simulation with detailed focus on network related effects such as mobility, scheduling and interference management must be emphasized. Existing studies evaluate user throughput and dimension LTE networks usually assuming uniform distribution of users within the cell. These studies report average user throughputs over the cell and the 5th percentile throughputs as estimates of the performance of the users ...

Assessing the implications of cellular network performance on mobile content access

DEFF Research Database (Denmark)

Kaup, Fabian; Michelinakis, Foivos; Bui, Nicola

2016-01-01

Mobile applications such as VoIP, (live) gaming, or video streaming have diverse QoS requirements ranging from low delay to high throughput. The optimization of the network quality experienced by end-users requires detailed knowledge of the expected network performance. Also, the achieved service...... of cellular network measurements, focused on analyzing root causes of mobile network performance variability. Measurements conducted on a 4G cellular network in Germany show that management and configuration decisions have a substantial impact on the performance. Specifically, it is observed...

Optical Performance Monitoring and Signal Optimization in Optical Networks

DEFF Research Database (Denmark)

Petersen, Martin Nordal

2006-01-01

The thesis studies performance monitoring for the next generation optical networks. The focus is on all-optical networks with bit-rates of 10 Gb/s or above. Next generation all-optical networks offer large challenges as the optical transmitted distance increases and the occurrence of electrical-optical......-electrical regeneration points decreases. This thesis evaluates the impact of signal degrading effects that are becoming of increasing concern in all-optical high-speed networks due to all-optical switching and higher bit-rates. Especially group-velocity-dispersion (GVD) and a number of nonlinear effects will require...... enhanced attention to avoid signal degradations. The requirements for optical performance monitoring features are discussed, and the thesis evaluates the advantages and necessity of increasing the level of performance monitoring parameters in the physical layer. In particular, methods for optical...

Statistical modelling of networked human-automation performance using working memory capacity.

Science.gov (United States)

Ahmed, Nisar; de Visser, Ewart; Shaw, Tyler; Mohamed-Ameen, Amira; Campbell, Mark; Parasuraman, Raja

2014-01-01

This study examines the challenging problem of modelling the interaction between individual attentional limitations and decision-making performance in networked human-automation system tasks. Analysis of real experimental data from a task involving networked supervision of multiple unmanned aerial vehicles by human participants shows that both task load and network message quality affect performance, but that these effects are modulated by individual differences in working memory (WM) capacity. These insights were used to assess three statistical approaches for modelling and making predictions with real experimental networked supervisory performance data: classical linear regression, non-parametric Gaussian processes and probabilistic Bayesian networks. It is shown that each of these approaches can help designers of networked human-automated systems cope with various uncertainties in order to accommodate future users by linking expected operating conditions and performance from real experimental data to observable cognitive traits like WM capacity. Practitioner Summary: Working memory (WM) capacity helps account for inter-individual variability in operator performance in networked unmanned aerial vehicle supervisory tasks. This is useful for reliable performance prediction near experimental conditions via linear models; robust statistical prediction beyond experimental conditions via Gaussian process models and probabilistic inference about unknown task conditions/WM capacities via Bayesian network models.

Switching performance of OBS network model under prefetched real traffic

Science.gov (United States)

Huang, Zhenhua; Xu, Du; Lei, Wen

2005-11-01

Optical Burst Switching (OBS) [1] is now widely considered as an efficient switching technique in building the next generation optical Internet .So it's very important to precisely evaluate the performance of the OBS network model. The performance of the OBS network model is variable in different condition, but the most important thing is that how it works under real traffic load. In the traditional simulation models, uniform traffics are usually generated by simulation software to imitate the data source of the edge node in the OBS network model, and through which the performance of the OBS network is evaluated. Unfortunately, without being simulated by real traffic, the traditional simulation models have several problems and their results are doubtable. To deal with this problem, we present a new simulation model for analysis and performance evaluation of the OBS network, which uses prefetched IP traffic to be data source of the OBS network model. The prefetched IP traffic can be considered as real IP source of the OBS edge node and the OBS network model has the same clock rate with a real OBS system. So it's easy to conclude that this model is closer to the real OBS system than the traditional ones. The simulation results also indicate that this model is more accurate to evaluate the performance of the OBS network system and the results of this model are closer to the actual situation.

High Performance Networks for High Impact Science

Energy Technology Data Exchange (ETDEWEB)

Scott, Mary A.; Bair, Raymond A.

2003-02-13

This workshop was the first major activity in developing a strategic plan for high-performance networking in the Office of Science. Held August 13 through 15, 2002, it brought together a selection of end users, especially representing the emerging, high-visibility initiatives, and network visionaries to identify opportunities and begin defining the path forward.

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

Copercolating Networks: An Approach for Realizing High-Performance Transparent Conductors using Multicomponent Nanostructured Networks

Directory of Open Access Journals (Sweden)

Das Suprem R.

2016-06-01

Full Text Available Although transparent conductive oxides such as indium tin oxide (ITO are widely employed as transparent conducting electrodes (TCEs for applications such as touch screens and displays, new nanostructured TCEs are of interest for future applications, including emerging transparent and flexible electronics. A number of twodimensional networks of nanostructured elements have been reported, including metallic nanowire networks consisting of silver nanowires, metallic carbon nanotubes (m-CNTs, copper nanowires or gold nanowires, and metallic mesh structures. In these single-component systems, it has generally been difficult to achieve sheet resistances that are comparable to ITO at a given broadband optical transparency. A relatively new third category of TCEs consisting of networks of 1D-1D and 1D-2D nanocomposites (such as silver nanowires and CNTs, silver nanowires and polycrystalline graphene, silver nanowires and reduced graphene oxide have demonstrated TCE performance comparable to, or better than, ITO. In such hybrid networks, copercolation between the two components can lead to relatively low sheet resistances at nanowire densities corresponding to high optical transmittance. This review provides an overview of reported hybrid networks, including a comparison of the performance regimes achievable with those of ITO and single-component nanostructured networks. The performance is compared to that expected from bulk thin films and analyzed in terms of the copercolation model. In addition, performance characteristics relevant for flexible and transparent applications are discussed. The new TCEs are promising, but significant work must be done to ensure earth abundance, stability, and reliability so that they can eventually replace traditional ITO-based transparent conductors.

The performance analysis of linux networking - packet receiving

Energy Technology Data Exchange (ETDEWEB)

Wu, Wenji; Crawford, Matt; Bowden, Mark; /Fermilab

2006-11-01

The computing models for High-Energy Physics experiments are becoming ever more globally distributed and grid-based, both for technical reasons (e.g., to place computational and data resources near each other and the demand) and for strategic reasons (e.g., to leverage equipment investments). To support such computing models, the network and end systems, computing and storage, face unprecedented challenges. One of the biggest challenges is to transfer scientific data sets--now in the multi-petabyte (10{sup 15} bytes) range and expected to grow to exabytes within a decade--reliably and efficiently among facilities and computation centers scattered around the world. Both the network and end systems should be able to provide the capabilities to support high bandwidth, sustained, end-to-end data transmission. Recent trends in technology are showing that although the raw transmission speeds used in networks are increasing rapidly, the rate of advancement of microprocessor technology has slowed down. Therefore, network protocol-processing overheads have risen sharply in comparison with the time spent in packet transmission, resulting in degraded throughput for networked applications. More and more, it is the network end system, instead of the network, that is responsible for degraded performance of network applications. In this paper, the Linux system's packet receive process is studied from NIC to application. We develop a mathematical model to characterize the Linux packet receiving process. Key factors that affect Linux systems network performance are analyzed.

Addressing the Influence of Hidden State on Wireless Network Optimizations using Performance Maps

DEFF Research Database (Denmark)

Højgaard-Hansen, Kim; Madsen, Tatiana Kozlova; Schwefel, Hans-Peter

2015-01-01

be used to optimize the use of the wireless net- work by predicting future network performance and scheduling the net- work communication for certain applications on mobile devices. However, other important factors influence the performance of the wireless communication such as changes in the propagation...... environment and resource sharing. In this work we extend the framework of performance maps for wireless networks by introducing network state as an abstraction for all other factors than location that influence the performance. Since network state might not always be directly observable the framework......Performance of wireless connectivity for network client devices is location dependent. It has been shown that it can be beneficial to collect network performance metrics along with location information to generate maps of the location dependent network performance. These performance maps can...

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...

Real-time video streaming in mobile cloud over heterogeneous wireless networks

Science.gov (United States)

Abdallah-Saleh, Saleh; Wang, Qi; Grecos, Christos

2012-06-01

Recently, the concept of Mobile Cloud Computing (MCC) has been proposed to offload the resource requirements in computational capabilities, storage and security from mobile devices into the cloud. Internet video applications such as real-time streaming are expected to be ubiquitously deployed and supported over the cloud for mobile users, who typically encounter a range of wireless networks of diverse radio access technologies during their roaming. However, real-time video streaming for mobile cloud users across heterogeneous wireless networks presents multiple challenges. The network-layer quality of service (QoS) provision to support high-quality mobile video delivery in this demanding scenario remains an open research question, and this in turn affects the application-level visual quality and impedes mobile users' perceived quality of experience (QoE). In this paper, we devise a framework to support real-time video streaming in this new mobile video networking paradigm and evaluate the performance of the proposed framework empirically through a lab-based yet realistic testing platform. One particular issue we focus on is the effect of users' mobility on the QoS of video streaming over the cloud. We design and implement a hybrid platform comprising of a test-bed and an emulator, on which our concept of mobile cloud computing, video streaming and heterogeneous wireless networks are implemented and integrated to allow the testing of our framework. As representative heterogeneous wireless networks, the popular WLAN (Wi-Fi) and MAN (WiMAX) networks are incorporated in order to evaluate effects of handovers between these different radio access technologies. The H.264/AVC (Advanced Video Coding) standard is employed for real-time video streaming from a server to mobile users (client nodes) in the networks. Mobility support is introduced to enable continuous streaming experience for a mobile user across the heterogeneous wireless network. Real-time video stream packets

Performance Analysis of Congestion Control Mechanism in Software Defined Network (SDN

Directory of Open Access Journals (Sweden)

Rahman M. Z. A.

2017-01-01

Full Text Available In the near future, the traditional networks architecture will be difficult to be managed. Hence, Software Defined Network (SDN will be an alternative in the future of programmable networks to replace the conventional network architecture. The main idea of SDN architecture is to separate the forwarding plane and control plane of network system, where network operators can program packet forwarding behaviour to improve the network performance. Congestion control is important mechanism for network traffic to improve network capability and achieve high end Quality of Service (QoS. In this paper, extensive simulation is conducted to analyse the performance of SDN by implementing Link Layer Discovery Protocol (LLDP under congested network. The simulation was conducted on Mininet by creating four different fanout and the result was analysed based on differences of matrix performance. As a result, the packet loss and throughput reduction were observed when number of fanout in the topology was increased. By using LLDP protocol, huge reduction in packet loss rate has been achieved while maximizing percentage packet delivery ratio.

Wireless ad hoc and sensor networks management, performance, and applications

CERN Document Server

He, Jing

2013-01-01

Although wireless sensor networks (WSNs) have been employed across a wide range of applications, there are very few books that emphasize the algorithm description, performance analysis, and applications of network management techniques in WSNs. Filling this need, Wireless Ad Hoc and Sensor Networks: Management, Performance, and Applications summarizes not only traditional and classical network management techniques, but also state-of-the-art techniques in this area. The articles presented are expository, but scholarly in nature, including the appropriate history background, a review of current

Classification of Company Performance using Weighted Probabilistic Neural Network

Science.gov (United States)

Yasin, Hasbi; Waridi Basyiruddin Arifin, Adi; Warsito, Budi

2018-05-01

Classification of company performance can be judged by looking at its financial status, whether good or bad state. Classification of company performance can be achieved by some approach, either parametric or non-parametric. Neural Network is one of non-parametric methods. One of Artificial Neural Network (ANN) models is Probabilistic Neural Network (PNN). PNN consists of four layers, i.e. input layer, pattern layer, addition layer, and output layer. The distance function used is the euclidean distance and each class share the same values as their weights. In this study used PNN that has been modified on the weighting process between the pattern layer and the addition layer by involving the calculation of the mahalanobis distance. This model is called the Weighted Probabilistic Neural Network (WPNN). The results show that the company's performance modeling with the WPNN model has a very high accuracy that reaches 100%.

Estimating cellular network performance during hurricanes

International Nuclear Information System (INIS)

Booker, Graham; Torres, Jacob; Guikema, Seth; Sprintson, Alex; Brumbelow, Kelly

2010-01-01

Cellular networks serve a critical role during and immediately after a hurricane, allowing citizens to contact emergency services when land-line communication is lost and serving as a backup communication channel for emergency responders. However, due to their ubiquitous deployment and limited design for extreme loading events, basic network elements, such as cellular towers and antennas are prone to failures during adverse weather conditions such as hurricanes. Accordingly, a systematic and computationally feasible approach is required for assessing and improving the reliability of cellular networks during hurricanes. In this paper we develop a new multi-disciplinary approach to efficiently and accurately assess cellular network reliability during hurricanes. We show how the performance of a cellular network during and immediately after future hurricanes can be estimated based on a combination of hurricane wind field models, structural reliability analysis, Monte Carlo simulation, and cellular network models and simulation tools. We then demonstrate the use of this approach for assessing the improvement in system reliability that can be achieved with discrete topological changes in the system. Our results suggest that adding redundancy, particularly through a mesh topology or through the addition of an optical fiber ring around the perimeter of the system can be an effective way to significantly increase the reliability of some cellular systems during hurricanes.

Performance Analysis of RF-FSO Multi-Hop Networks

KAUST Repository

Makki, Behrooz

2017-05-12

We study the performance of multi-hop networks composed of millimeter wave (MMW)-based radio frequency (RF) and free-space optical (FSO) links. The results are obtained in the cases with and without hybrid automatic repeat request (HARQ). Taking the MMW characteristics of the RF links into account, we derive closed-form expressions for the network outage probability. We also evaluate the effect of various parameters such as power amplifiers efficiency, number of antennas as well as different coherence times of the RF and the FSO links on the system performance. Finally, we present mappings between the performance of RF- FSO multi-hop networks and the ones using only the RF- or the FSO-based communication, in the sense that with appropriate parameter settings the same outage probability is achieved in these setups. The results show the efficiency of the RF-FSO setups in different conditions. Moreover, the HARQ can effectively improve the outage probability/energy efficiency, and compensate the effect of hardware impairments in RF-FSO networks. For common parameter settings of the RF-FSO dual- hop networks, outage probability 10^{-4} and code rate 3 nats-per-channel-use, the implementation of HARQ with a maximum of 2 and 3 retransmissions reduces the required power, compared to the cases with no HARQ, by 13 and 17 dB, respectively.

Hospital network performance: a survey of hospital stakeholders' perspectives.

Science.gov (United States)

Bravi, F; Gibertoni, D; Marcon, A; Sicotte, C; Minvielle, E; Rucci, P; Angelastro, A; Carradori, T; Fantini, M P

2013-02-01

Hospital networks are an emerging organizational form designed to face the new challenges of public health systems. Although the benefits introduced by network models in terms of rationalization of resources are known, evidence about stakeholders' perspectives on hospital network performance from the literature is scanty. Using the Competing Values Framework of organizational effectiveness and its subsequent adaptation by Minvielle et al., we conducted in 2009 a survey in five hospitals of an Italian network for oncological care to examine and compare the views on hospital network performance of internal stakeholders (physicians, nurses and the administrative staff). 329 questionnaires exploring stakeholders' perspectives were completed, with a response rate of 65.8%. Using exploratory factor analysis of the 66 items of the questionnaire, we identified 4 factors, i.e. Centrality of relationships, Quality of care, Attractiveness/Reputation and Staff empowerment and Protection of workers' rights. 42 items were retained in the analysis. Factor scores proved to be high (mean score>8 on a 10-item scale), except for Attractiveness/Reputation (mean score 6.79), indicating that stakeholders attach a higher importance to relational and health care aspects. Comparison of factor scores among stakeholders did not reveal significant differences, suggesting a broadly shared view on hospital network performance. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Environmental investment and firm performance: A network approach

International Nuclear Information System (INIS)

Bostian, Moriah; Färe, Rolf; Grosskopf, Shawna; Lundgren, Tommy

2016-01-01

This study examines the role of investment in environmental production practices for both environmental performance and energy efficiency over time. We employ a network DEA approach that links successive production technologies through intertemporal investment decisions with a period by period estimation. This allows us to estimate energy efficiency and environmental performance separately, as well as productivity change and its associated decompositions into efficiency change and technology change. Incorporating a network model also allows us to account for both short-term environmental management practices and long-term environmental investments in each of our productivity measures. We apply this framework to a panel of detailed plant-level production data for Swedish manufacturing firms covering the years 2002–2008. - Highlights: • We use a network DEA model to account for intertemporal environmental investment decisionsin measures of firm productivity. • We apply our network technology model to a panel of firms in Sweden's pulp and paperindustry for the years 2002 - 2008. • We model environmental investments and expenditures separately from other productionoriented inputs. • We find evidence of positive relationships between energy efficiency, environmental performance, and firm productivity.

The Sandblaster Software-Defined Radio Platform for Mobile 4G Wireless Communications

Directory of Open Access Journals (Sweden)

V. Surducan

2009-01-01

Full Text Available We present a tier 2 Software Defined-Radio platform (SDR, built around the latest Sandbridge Technologies' multithreaded Digital Signal Processor (DSP SB3500, along with the description of major design steps taken to ensure the best radio link and computational performance. This SDR platform is capable of executing 4G wireless communication standards such as WiMAX Wave 2, WLAN 802.11 g, and LTE. Performance results for WiMAX are presented in the conclusion section.

A Performance Evaluation Model for Mobile Ad Hoc Networks and Sensor Networks

Directory of Open Access Journals (Sweden)

Heng LUO

2014-03-01

Full Text Available Potential applications in areas such as military sites and disaster relief fields that are characterized by absence of prefixed infrastructure justify the development of mobile ad hoc networks (MANETs and wireless sensor networks (WSNs. However, unfavorable wireless links and dynamic topology are still challenging, leading to the proposal of a collection of routing protocols for MANETs and WSNs. Nevertheless the performance of algorithms may vary with deployment scenario due to the application dependent philosophy behind algorithms. In this paper, the performance evaluation problem for MANETs and WSNs is investigated and a novel performance ranking model, termed AHP-SAW, is proposed. For simplicity but without loss of generality, the performance of two routing protocols DSDV and DSR are studies based on which ranking results are provided. Extensive simulations show that an overall 37.2 %, at most, gain may be achieved based on the AHP-SAW model.

Topological Effects and Performance Optimization in Transportation Continuous Network Design

Directory of Open Access Journals (Sweden)

Jianjun Wu

2014-01-01

Full Text Available Because of the limitation of budget, in the planning of road works, increased efforts should be made on links that are more critical to the whole traffic system. Therefore, it would be helpful to model and evaluate the vulnerability and reliability of the transportation network when the network design is processing. This paper proposes a bilevel transportation network design model, in which the upper level is to minimize the performance of the network under the given budgets, while the lower level is a typical user equilibrium assignment problem. A new solution approach based on particle swarm optimization (PSO method is presented. The topological effects on the performance of transportation networks are studied with the consideration of three typical networks, regular lattice, random graph, and small-world network. Numerical examples and simulations are presented to demonstrate the proposed model.

Performance evaluation of packet video transfer over local area networks

OpenAIRE

Lu, Jie

1993-01-01

This research investigates the implementation and performance of packet video transfer over local area networks. A network architecture is defined for packet video such that most of the processing is performed by the higher layers of the Open Systems Interconnection (OSI) reference model, while the lower layers provide real-time services. Implementation methods are discussed for coding schemes, including data compression, the network interface unit, and the underlying local are...

A Mathematical Model to Improve the Performance of Logistics Network

Directory of Open Access Journals (Sweden)

Muhammad Izman Herdiansyah

2012-01-01

Full Text Available The role of logistics nowadays is expanding from just providing transportation and warehousing to offering total integrated logistics. To remain competitive in the global market environment, business enterprises need to improve their logistics operations performance. The improvement will be achieved when we can provide a comprehensive analysis and optimize its network performances. In this paper, a mixed integer linier model for optimizing logistics network performance is developed. It provides a single-product multi-period multi-facilities model, as well as the multi-product concept. The problem is modeled in form of a network flow problem with the main objective to minimize total logistics cost. The problem can be solved using commercial linear programming package like CPLEX or LINDO. Even in small case, the solver in Excel may also be used to solve such model.Keywords: logistics network, integrated model, mathematical programming, network optimization

Evaluation of Techniques to Detect Significant Network Performance Problems using End-to-End Active Network Measurements

Energy Technology Data Exchange (ETDEWEB)

Cottrell, R.Les; Logg, Connie; Chhaparia, Mahesh; /SLAC; Grigoriev, Maxim; /Fermilab; Haro, Felipe; /Chile U., Catolica; Nazir, Fawad; /NUST, Rawalpindi; Sandford, Mark

2006-01-25

End-to-End fault and performance problems detection in wide area production networks is becoming increasingly hard as the complexity of the paths, the diversity of the performance, and dependency on the network increase. Several monitoring infrastructures are built to monitor different network metrics and collect monitoring information from thousands of hosts around the globe. Typically there are hundreds to thousands of time-series plots of network metrics which need to be looked at to identify network performance problems or anomalous variations in the traffic. Furthermore, most commercial products rely on a comparison with user configured static thresholds and often require access to SNMP-MIB information, to which a typical end-user does not usually have access. In our paper we propose new techniques to detect network performance problems proactively in close to realtime and we do not rely on static thresholds and SNMP-MIB information. We describe and compare the use of several different algorithms that we have implemented to detect persistent network problems using anomalous variations analysis in real end-to-end Internet performance measurements. We also provide methods and/or guidance for how to set the user settable parameters. The measurements are based on active probes running on 40 production network paths with bottlenecks varying from 0.5Mbits/s to 1000Mbit/s. For well behaved data (no missed measurements and no very large outliers) with small seasonal changes most algorithms identify similar events. We compare the algorithms' robustness with respect to false positives and missed events especially when there are large seasonal effects in the data. Our proposed techniques cover a wide variety of network paths and traffic patterns. We also discuss the applicability of the algorithms in terms of their intuitiveness, their speed of execution as implemented, and areas of applicability. Our encouraging results compare and evaluate the accuracy of our

Use of communication architecture test bed to evaluate data network performance

International Nuclear Information System (INIS)

Clapp, N.E. Jr.; Swail, B.K.; Naser, J.A.

1994-01-01

Local area networks (LANs) are becoming more prevalent in nuclear power plants. Traditionally, LANs were only used as information highways, providing office automation services. LANs are now being used as data highways for applications in plant data acquisition and control systems. A communication architecture test bed, which contains network simulators, is needed to allow network performance studies and to resolve design issues prior to equipment purchase. Two levels of granularity of simulation are needed to provide the dynamic information about network performance. A coarse-grain simulator is used to estimate the dynamic performance of the network due to major resources such as workstations, gateways, and data acquisition systems. A fine-grain simulator allows a greater level of detail about the underlying network protocol and resources to be simulated. The combination of coarse-grain and fine-grain simulation packages provides the network designer with the required tools to thoroughly understand the behavior of the modeled network. This paper describes the development of a communication architecture test bed using commercial network simulation packages. Network simulators allow the resolution of major design issues in software without the expense of purchasing costly hardware components

Optimisation of Software-Defined Networks Performance Using a Hybrid Intelligent System

Directory of Open Access Journals (Sweden)

Ann Sabih

2017-06-01

Full Text Available This paper proposes a novel intelligent technique that has been designed to optimise the performance of Software Defined Networks (SDN. The proposed hybrid intelligent system has employed integration of intelligence-based optimisation approaches with the artificial neural network. These heuristic optimisation methods include Genetic Algorithms (GA and Particle Swarm Optimisation (PSO. These methods were utilised separately in order to select the best inputs to maximise SDN performance. In order to identify SDN behaviour, the neural network model is trained and applied. The maximal optimisation approach has been identified using an analytical approach that considered SDN performance and the computational time as objective functions. Initially, the general model of the neural network was tested with unseen data before implementing the model using GA and PSO to determine the optimal performance of SDN. The results showed that the SDN represented by Artificial Neural Network ANN, and optmised by PSO, generated a better configuration with regards to computational efficiency and performance index.

Performance Analysis of On-Demand Routing Protocols in Wireless Mesh Networks

Directory of Open Access Journals (Sweden)

Arafatur RAHMAN

2009-01-01

Full Text Available Wireless Mesh Networks (WMNs have recently gained a lot of popularity due to their rapid deployment and instant communication capabilities. WMNs are dynamically self-organizing, self-configuring and self-healing with the nodes in the network automatically establishing an adiej hoc network and preserving the mesh connectivity. Designing a routing protocol for WMNs requires several aspects to consider, such as wireless networks, fixed applications, mobile applications, scalability, better performance metrics, efficient routing within infrastructure, load balancing, throughput enhancement, interference, robustness etc. To support communication, various routing protocols are designed for various networks (e.g. ad hoc, sensor, wired etc.. However, all these protocols are not suitable for WMNs, because of the architectural differences among the networks. In this paper, a detailed simulation based performance study and analysis is performed on the reactive routing protocols to verify the suitability of these protocols over such kind of networks. Ad Hoc On-Demand Distance Vector (AODV, Dynamic Source Routing (DSR and Dynamic MANET On-demand (DYMO routing protocol are considered as the representative of reactive routing protocols. The performance differentials are investigated using varying traffic load and number of source. Based on the simulation results, how the performance of each protocol can be improved is also recommended.

Advanced Multimode Radio for Wireless & Mobile Broadband Communication

DEFF Research Database (Denmark)

Kardaras, Georgios; Lanzani, Christian

2009-01-01

Distributed base station architectures represent the new trend that operators follow in order to resolve cost, performance and efficiency challenges when deploying 4G networks. Main components of such architectures are multimode radios capable of operating according to GSM, HSPA, WiMAX and LTE...... of a digital predistortion (DPD) block is emphasized and an adaptive polynomial approach based on cartesian to polar conversion is then proposed. Such radio architecture has successfully been implemented on a low-cost FPGA family meeting the WiMAX/LTE spectrum and Error Vector Magnitude (EVM) requirements....

Evaluation of high-performance network technologies for ITER

International Nuclear Information System (INIS)

Zagar, K.; Hunt, S.; Kolaric, P.; Sabjan, R.; Zagar, A.; Dedic, J.

2010-01-01

For the fast feedback plasma controllers, ITER's Control, Data Access and Communication system (CODAC) will need to provide a mechanism for hard real-time communication between its distributed nodes. In particular, the ITER CODAC team identified four types of high-performance communication applications. Synchronous Databus Network (SDN) is to provide an ability to distribute parameters of plasma (estimated to about 5000 double-valued signals) across the system to allow for 1 ms control cycles. Event Distribution Network (EDN) and Time Communication Network (TCN) are to allow synchronization of node I/O operations to 10 ns. Finally, the Audio-Video Network (AVN) is to provide sufficient bandwidth for streaming of surveillance and diagnostics video at a high resolution (1024 x 1024) and frame rate (30 Hz). In this article, we present some combinations of common-off-the-shelf (COTS) technologies that allow the above requirements to be met. Also, we present the performances achieved in a practical (though small scale) technology demonstrator, which involved a real-time Linux operating running on National Instruments' PXI platform, UDP communication implemented directly atop the Ethernet network adapter, CISCO switches, Micro Research Finland's timing and event solution, and GigE audio-video streaming.

An Analysis of Network and Sensor Performance Within IEEE 802.X Wireless MESH Networks in the Tactical Network Topology (TNT)

National Research Council Canada - National Science Library

Davis, Joseph A., Sr

2005-01-01

.... Specifically, this thesis will attempt establish the foundation for the development of wireless MESH "network health" models by examining the performance of sensors operating within a MESH network...

A Step towards Developing a Sustainability Performance Measure within Industrial Networks

Directory of Open Access Journals (Sweden)

Samaneh Shokravi

2014-04-01

Full Text Available Despite the plethora of literature in sustainability and supply chain management in the recent years, a quantitative tool that measures the sustainability performance of an industrial supply network, considering the uncertainties of existing data, is hard to find. This conceptual paper is aimed at establishing a quantitative measure for the sustainability performance of industrial supply networks that considers aleatory and epistemic uncertainties in its environmental performance evaluation. The measure is built upon economic, environmental and social performance evaluation models. These models address a number of shortcomings in the literature, such as incomplete and inaccurate calculation of environmental impacts, as well as the disregard for aleatory and epistemic uncertainties in the input data and, more importantly, the scarce number of quantitative social sustainability measures. Dyadic interactions are chosen for the network, while the network members have a revenue-sharing relationship. This relationship promotes sharing of the required information for the use of the proposed model. This measure provides an approach to quantify the environmental, social and economic sustainability performances of a supply network. Moreover, as this measure is not specifically designed for an industrial sector, it can be employed over an evolving and diverse industrial network.

High Performance Networks From Supercomputing to Cloud Computing

CERN Document Server

Abts, Dennis

2011-01-01

Datacenter networks provide the communication substrate for large parallel computer systems that form the ecosystem for high performance computing (HPC) systems and modern Internet applications. The design of new datacenter networks is motivated by an array of applications ranging from communication intensive climatology, complex material simulations and molecular dynamics to such Internet applications as Web search, language translation, collaborative Internet applications, streaming video and voice-over-IP. For both Supercomputing and Cloud Computing the network enables distributed applicati

Integrated healthcare networks' performance: a growth curve modeling approach.

Science.gov (United States)

Wan, Thomas T H; Wang, Bill B L

2003-05-01

This study examines the effects of integration on the performance ratings of the top 100 integrated healthcare networks (IHNs) in the United States. A strategic-contingency theory is used to identify the relationship of IHNs' performance to their structural and operational characteristics and integration strategies. To create a database for the panel study, the top 100 IHNs selected by the SMG Marketing Group in 1998 were followed up in 1999 and 2000. The data were merged with the Dorenfest data on information system integration. A growth curve model was developed and validated by the Mplus statistical program. Factors influencing the top 100 IHNs' performance in 1998 and their subsequent rankings in the consecutive years were analyzed. IHNs' initial performance scores were positively influenced by network size, number of affiliated physicians and profit margin, and were negatively associated with average length of stay and technical efficiency. The continuing high performance, judged by maintaining higher performance scores, tended to be enhanced by the use of more managerial or executive decision-support systems. Future studies should include time-varying operational indicators to serve as predictors of network performance.

Topology design and performance analysis of an integrated communication network

Science.gov (United States)

Li, V. O. K.; Lam, Y. F.; Hou, T. C.; Yuen, J. H.

1985-01-01

A research study on the topology design and performance analysis for the Space Station Information System (SSIS) network is conducted. It is begun with a survey of existing research efforts in network topology design. Then a new approach for topology design is presented. It uses an efficient algorithm to generate candidate network designs (consisting of subsets of the set of all network components) in increasing order of their total costs, and checks each design to see if it forms an acceptable network. This technique gives the true cost-optimal network, and is particularly useful when the network has many constraints and not too many components. The algorithm for generating subsets is described in detail, and various aspects of the overall design procedure are discussed. Two more efficient versions of this algorithm (applicable in specific situations) are also given. Next, two important aspects of network performance analysis: network reliability and message delays are discussed. A new model is introduced to study the reliability of a network with dependent failures. For message delays, a collection of formulas from existing research results is given to compute or estimate the delays of messages in a communication network without making the independence assumption. The design algorithm coded in PASCAL is included as an appendix.

Performance verification of network function virtualization in software defined optical transport networks

Science.gov (United States)

Zhao, Yongli; Hu, Liyazhou; Wang, Wei; Li, Yajie; Zhang, Jie

2017-01-01

With the continuous opening of resource acquisition and application, there are a large variety of network hardware appliances deployed as the communication infrastructure. To lunch a new network application always implies to replace the obsolete devices and needs the related space and power to accommodate it, which will increase the energy and capital investment. Network function virtualization1 (NFV) aims to address these problems by consolidating many network equipment onto industry standard elements such as servers, switches and storage. Many types of IT resources have been deployed to run Virtual Network Functions (vNFs), such as virtual switches and routers. Then how to deploy NFV in optical transport networks is a of great importance problem. This paper focuses on this problem, and gives an implementation architecture of NFV-enabled optical transport networks based on Software Defined Optical Networking (SDON) with the procedure of vNFs call and return. Especially, an implementation solution of NFV-enabled optical transport node is designed, and a parallel processing method for NFV-enabled OTN nodes is proposed. To verify the performance of NFV-enabled SDON, the protocol interaction procedures of control function virtualization and node function virtualization are demonstrated on SDON testbed. Finally, the benefits and challenges of the parallel processing method for NFV-enabled OTN nodes are simulated and analyzed.

Planning Multitechnology Access Networks with Performance Constraints

Science.gov (United States)

Chamberland, Steven

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

Evaluation of High-Performance Network Technologies for ITER

Energy Technology Data Exchange (ETDEWEB)

Zagar, K.; Kolaric, P.; Sabjan, R.; Zagar, A. [Cosylab d.d., Ljubljana (Slovenia); Hunt, S. [Alceli Hunt Beratung, Meisterschwanden (Switzerland)

2009-07-01

To facilitate fast feedback control of plasma, ITER's Control, Data Access and Communication system (CODAC) will need to provide a mechanism for hard real-time communication between its distributed nodes. In particular, four types of high-performance communication have been identified. Synchronous Databus Network (SDN) is to provide an ability to distribute parameters of plasma (estimated to about 5000 double-valued signals) across the system to allow for 1 ms control cycles. Event Distribution Network (EDN) and Time Communication Network (TCN) are to allow synchronization of node I/O operations to 10 ns. Finally, the Audio Video Network (AVN) is to provide sufficient bandwidth for streaming of surveillance and diagnostics video at a high resolution (1024*1024) and frame rate (30 Hz). In this article, we present some combinations of common off-the-shelf (COTS) technologies that allow the above requirements to be met. Also, we present the performances achieved in a practical (though small scale) technology demonstrator, which involved a real-time LINUS operating running on National Instruments' PXI platform, UDP communication implemented directly atop the Ethernet network adapter, CISCO switches, Micro Research Finland's timing and event solution, and GigE audio-video streaming. This document is composed of an abstract followed by the presentation transparencies. (authors)

Evaluation of high-performance network technologies for ITER

Energy Technology Data Exchange (ETDEWEB)

Zagar, K., E-mail: klemen.zagar@cosylab.co [Cosylab d.d., 1000 Ljubljana (Slovenia); Hunt, S. [Alceli Hunt Beratung, 5616 Meisterschwanden (Switzerland); Kolaric, P.; Sabjan, R.; Zagar, A.; Dedic, J. [Cosylab d.d., 1000 Ljubljana (Slovenia)

2010-07-15

For the fast feedback plasma controllers, ITER's Control, Data Access and Communication system (CODAC) will need to provide a mechanism for hard real-time communication between its distributed nodes. In particular, the ITER CODAC team identified four types of high-performance communication applications. Synchronous Databus Network (SDN) is to provide an ability to distribute parameters of plasma (estimated to about 5000 double-valued signals) across the system to allow for 1 ms control cycles. Event Distribution Network (EDN) and Time Communication Network (TCN) are to allow synchronization of node I/O operations to 10 ns. Finally, the Audio-Video Network (AVN) is to provide sufficient bandwidth for streaming of surveillance and diagnostics video at a high resolution (1024 x 1024) and frame rate (30 Hz). In this article, we present some combinations of common-off-the-shelf (COTS) technologies that allow the above requirements to be met. Also, we present the performances achieved in a practical (though small scale) technology demonstrator, which involved a real-time Linux operating running on National Instruments' PXI platform, UDP communication implemented directly atop the Ethernet network adapter, CISCO switches, Micro Research Finland's timing and event solution, and GigE audio-video streaming.

Testing the Feasibility of a Low-Cost Network Performance Measurement Infrastructure

Energy Technology Data Exchange (ETDEWEB)

Chevalier, Scott [Indiana Univ., Bloomington, IN (United States). International Networks; Schopf, Jennifer M. [Indiana Univ., Bloomington, IN (United States). International Networks; Miller, Kenneth [Pennsylvania State Univ., University Park, PA (United States). Telecommunications and Networking Services; Zurawski, Jason [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Energy Sciences Network

2016-07-01

Todays science collaborations depend on reliable, high performance networks, but monitoring the end-to-end performance of a network can be costly and difficult. The most accurate approaches involve using measurement equipment in many locations, which can be both expensive and difficult to manage due to immobile or complicated assets. The perfSONAR framework facilitates network measurement making management of the tests more reasonable. Traditional deployments have used over-provisioned servers, which can be expensive to deploy and maintain. As scientific network uses proliferate, there is a desire to instrument more facets of a network to better understand trends. This work explores low cost alternatives to assist with network measurement. Benefits include the ability to deploy more resources quickly, and reduced capital and operating expenditures. Finally, we present candidate platforms and a testing scenario that evaluated the relative merits of four types of small form factor equipment to deliver accurate performance measurements.

The Effects of Nonperforming Loans on Dynamic Network Bank Performance

Directory of Open Access Journals (Sweden)

Day-Yang Liu

2017-01-01

Full Text Available This paper is to explore the relationship between banks’ performance and their nonperforming loans (NPLs. The banks’ performance through a network production process structure with NPLs is developed. With increasing NPLs in recent years, the quality of lending assets is a key significant and influencing factor for banks’ operational risk. The research methodology is to integrate the radial and nonradial measures of efficiency into the network production process framework with NPLs; this study utilizes network epsilon-based measure model to evaluate the banking industry performance. In addition, the key characteristics of the bank industry including those of financial holding companies and privatized government banks are needed to be figured out and to provide insight into what causes imperfectly competitive conditions for some banks. The results demonstrate that the banking sector grew consistently in three aspects of operation: operating performance, profitability performance, and risk management in the last five years of the subject period. These results showed that the overall banking sector was capable of pursuing growth in both operations and profits while accounting for risk management. The potential applications and strengths of network data envelopment analysis in assessing financial organizations are also highlighted.

Optical Switching for Dynamic Distribution of Wireless-Over-Fiber Signals in Active Optical Networks

DEFF Research Database (Denmark)

Vegas Olmos, Juan José; Rodes, Guillermo; Tafur Monroy, Idelfonso

2012-01-01

In this paper, we report on an experimental validation of dynamic distribution of wireless-over-fiber by employing optical switching using semiconductor optical amplifiers; we also provide a channel distribution scheme and a generic topology for such an optical switch. The experiment consists...... of a four wavelength-division-multiplexed channel system operating on a WiMax frequency band and employing an orthogonal-frequency-division-multiplexing modulation at 625 Mbits/s per channel, transmission of the data over 20 km of optical fiber, and active switching in a 1 × 16 active optical switch....... The results show a negligible power penalty on each channel for both the best and the worst case in terms of inter-channel crosstalk. The presented system is highly scalable both in terms of port count and throughput, a desirable feature in highly branched access networks, and is modulation- and frequency...

Network meta-analyses performed by contracting companies and commissioned by industry

NARCIS (Netherlands)

Schuit, Ewoud; Ioannidis, John P A

2016-01-01

Background: Industry commissions contracting companies to perform network meta-analysis for health technology assessment (HTA) and reimbursement submissions. Our objective was to estimate the number of network meta-analyses performed by consulting companies contracted by industry, to assess whether

Network analysis of patient flow in two UK acute care hospitals identifies key sub-networks for A&E performance.

Science.gov (United States)

Bean, Daniel M; Stringer, Clive; Beeknoo, Neeraj; Teo, James; Dobson, Richard J B

2017-01-01

The topology of the patient flow network in a hospital is complex, comprising hundreds of overlapping patient journeys, and is a determinant of operational efficiency. To understand the network architecture of patient flow, we performed a data-driven network analysis of patient flow through two acute hospital sites of King's College Hospital NHS Foundation Trust. Administration databases were queried for all intra-hospital patient transfers in an 18-month period and modelled as a dynamic weighted directed graph. A 'core' subnetwork containing only 13-17% of all edges channelled 83-90% of the patient flow, while an 'ephemeral' network constituted the remainder. Unsupervised cluster analysis and differential network analysis identified sub-networks where traffic is most associated with A&E performance. Increased flow to clinical decision units was associated with the best A&E performance in both sites. The component analysis also detected a weekend effect on patient transfers which was not associated with performance. We have performed the first data-driven hypothesis-free analysis of patient flow which can enhance understanding of whole healthcare systems. Such analysis can drive transformation in healthcare as it has in industries such as manufacturing.

IMPACT OF SOCIAL NETWORK STRUCTURE ON EMPLOYEE PERFORMANCE: A COMPARATIVE STUDY

Directory of Open Access Journals (Sweden)

Claudio Lira Meirelles

2013-12-01

Full Text Available This research sought to understand the relationship between the position of the central actor and the performance of a network, checking the influence of the central actor's performance over other actors. Among the specific objectives, we sought to describe the transactional content, the nature of the connections and the structural characteristics of the network. Data were collected through a questionnaire and analyzed with the help of software UCINET 6.0 and Excel. The results suggest that the performance of the actors with the highest levels of centrality is related to the performance of the actors of the 1st step of sub-networks of these central actors.

Design, deployment and performance of 4G-LTE networks a practical approach

CERN Document Server

ElNashar, Ayman; Sherif, Mahmoud

2014-01-01

This book provides an insight into the key practical aspects and best practice of 4G-LTE network design, performance, and deployment Design, Deployment and Performance of 4G-LTE Networks addresses the key practical aspects and best practice of 4G networks design, performance, and deployment. In addition, the book focuses on the end-to-end aspects of the LTE network architecture and different deployment scenarios of commercial LTE networks. It describes the air interface of LTE focusing on the access stratum protocol layers: PDCP, RLC, MAC, and Physical Layer. The air interface described in this book covers the concepts of LTE frame structure, downlink and uplink scheduling, and detailed illustrations of the data flow across the protocol layers. It describes the details of the optimization process including performance measurements and troubleshooting mechanisms in addition to demonstrating common issues and case studies based on actual field results. The book provides detailed performance analysis of key fe...

Mitigating the controller performance bottlenecks in Software Defined Networks

DEFF Research Database (Denmark)

Caba, Cosmin Marius; Soler, José

2016-01-01

The centralization of the control plane decision logic in Software Defined Networking (SDN) has raised concerns regarding the performance of the SDN Controller (SDNC) when the network scales up. A number of solutions have been proposed in the literature to address these concerns. This paper...

Performance analysis and improvement of WPAN MAC for home networks.

Science.gov (United States)

Mehta, Saurabh; Kwak, Kyung Sup

2010-01-01

The wireless personal area network (WPAN) is an emerging wireless technology for future short range indoor and outdoor communication applications. The IEEE 802.15.3 medium access control (MAC) is proposed to coordinate the access to the wireless medium among the competing devices, especially for short range and high data rate applications in home networks. In this paper we use analytical modeling to study the performance analysis of WPAN (IEEE 802.15.3) MAC in terms of throughput, efficient bandwidth utilization, and delay with various ACK policies under error channel condition. This allows us to introduce a K-Dly-ACK-AGG policy, payload size adjustment mechanism, and Improved Backoff algorithm to improve the performance of the WPAN MAC. Performance evaluation results demonstrate the impact of our improvements on network capacity. Moreover, these results can be very useful to WPAN application designers and protocol architects to easily and correctly implement WPAN for home networking.

Performance Analysis and Improvement of WPAN MAC for Home Networks

Directory of Open Access Journals (Sweden)

Saurabh Mehta

2010-03-01

Full Text Available The wireless personal area network (WPAN is an emerging wireless technology for future short range indoor and outdoor communication applications. The IEEE 802.15.3 medium access control (MAC is proposed to coordinate the access to the wireless medium among the competing devices, especially for short range and high data rate applications in home networks. In this paper we use analytical modeling to study the performance analysis of WPAN (IEEE 802.15.3 MAC in terms of throughput, efficient bandwidth utilization, and delay with various ACK policies under error channel condition. This allows us to introduce a K-Dly-ACK-AGG policy, payload size adjustment mechanism, and Improved Backoff algorithm to improve the performance of the WPAN MAC. Performance evaluation results demonstrate the impact of our improvements on network capacity. Moreover, these results can be very useful to WPAN application designers and protocol architects to easily and correctly implement WPAN for home networking.

Performance evaluation of a high-speed switched network for PACS

Science.gov (United States)

Zhang, Randy H.; Tao, Wenchao; Huang, Lu J.; Valentino, Daniel J.

1998-07-01

We have replaced our shared-media Ethernet and FDDI network with a multi-tiered, switched network using OC-12 (622 Mbps) ATM for the network backbone, OC3 (155 Mbps) connections to high-end servers and display workstations, and switched 100/10 Mbps Ethernet for workstations and desktop computers. The purpose of this research was to help PACS designers and implementers understand key performance factors in a high- speed switched network by characterizing and evaluating its image delivery performance, specifically, the performance of socket-based TCP (Transmission Control Protocol) and DICOM 3.0 communications. A test network within the UCLA Clinical RIS/PACS was constructed using Sun UltraSPARC-II machines with ATM, Fast Ethernet, and Ethernet network interfaces. To identify performance bottlenecks, we evaluated network throughput for memory to memory, memory to disk, disk to memory, and disk to disk transfers. To evaluate the effect of file size, tests involving disks were further divided using sizes of small (514 KB), medium (8 MB), and large (16 MB) files. The observed maximum throughput for various network configurations using the TCP protocol was 117 Mbps for memory to memory and 88 MBPS for memory to disk. For disk to memory, the peak throughput was 98 Mbps using small files, 114 Mbps using medium files, and 116 Mbps using large files. The peak throughput for disk to disk became 64 Mbps using small files and 96 Mbps using medium and large files. The peak throughput using the DICOM 3.0 protocol was substantially lower in all categories. The measured throughput varied significantly among the tests when TCP socket buffer was raised above the default value. The optimal buffer size was approximately 16 KB or the TCP protocol and around 256 KB for the DICOM protocol. The application message size also displayed distinctive effects on network throughput when the TCP socket buffer size was varied. The throughput results for Fast Ethernet and Ethernet were expectedly

Sustainable Performance in Energy Harvesting - Wireless Sensor Networks

DEFF Research Database (Denmark)

Fafoutis, Xenofon; Di Mauro, Alessio; Dragoni, Nicola

2013-01-01

In this practical demo we illustrate the concept of "sustainable performance" in Energy-Harvesting Wireless Sensor Networks (EH-WSNs). In particular, for different classes of applications and under several energy harvesting scenarios, we show how it is possible to have sustainable performance when...

Improvement of Networked Control Systems Performance Using a New Encryption Algorithm

Directory of Open Access Journals (Sweden)

Seyed Ali Mesbahifard

2014-07-01

Full Text Available Networked control systems are control systems which controllers and plants are connected via telecommunication network. One of the most important challenges in networked control systems is the problem of network time delay. Increasing of time delay may affect on control system performance extremely. Other important issue in networked control systems is the security problems. Since it is possible that unknown people access to network especially Internet, the probability of terrible attacks such as deception attacks is greater, therefore presentation of methods which could decrease time delay and increase system immunity are desired. In this paper a symmetric encryption with low data volume against deception attacks is proposed. This method has high security and low time delay rather than the other encryption algorithms and could improve the control system performance against deception attacks.

Performance modeling, stochastic networks, and statistical multiplexing

CERN Document Server

Mazumdar, Ravi R

2013-01-01

This monograph presents a concise mathematical approach for modeling and analyzing the performance of communication networks with the aim of introducing an appropriate mathematical framework for modeling and analysis as well as understanding the phenomenon of statistical multiplexing. The models, techniques, and results presented form the core of traffic engineering methods used to design, control and allocate resources in communication networks.The novelty of the monograph is the fresh approach and insights provided by a sample-path methodology for queueing models that highlights the importan

PERFORMANCE COMPARISON FOR INTRUSION DETECTION SYSTEM USING NEURAL NETWORK WITH KDD DATASET

Directory of Open Access Journals (Sweden)

S. Devaraju

2014-04-01

Full Text Available Intrusion Detection Systems are challenging task for finding the user as normal user or attack user in any organizational information systems or IT Industry. The Intrusion Detection System is an effective method to deal with the kinds of problem in networks. Different classifiers are used to detect the different kinds of attacks in networks. In this paper, the performance of intrusion detection is compared with various neural network classifiers. In the proposed research the four types of classifiers used are Feed Forward Neural Network (FFNN, Generalized Regression Neural Network (GRNN, Probabilistic Neural Network (PNN and Radial Basis Neural Network (RBNN. The performance of the full featured KDD Cup 1999 dataset is compared with that of the reduced featured KDD Cup 1999 dataset. The MATLAB software is used to train and test the dataset and the efficiency and False Alarm Rate is measured. It is proved that the reduced dataset is performing better than the full featured dataset.

Accés per Multiplexació de Freqüències Ortogonals per Xarxes Òptiques Passives: una aproximació práctica

OpenAIRE

Peralta Gallardo, Ángel

2012-01-01

OFDMA applied for future optical networks [ANGLÈS] Research activities for new alternatives in ultra fast transmission over optical fiber networks are looking towards Orthogonal Frequency Division Multiplexing (OFDM) which is used in different modern communication systems such as LTE, WiFi or WiMax because of the following reasons: tolerance to channel limitations, better spectral exploitation, scalability, flexibility and implementation feasibility with state of the art electronics. These...

THE USE OF NEURAL NETWORK TECHNOLOGY TO MODEL SWIMMING PERFORMANCE

Directory of Open Access Journals (Sweden)

António José Silva

2007-03-01

Full Text Available The aims of the present study were: to identify the factors which are able to explain the performance in the 200 meters individual medley and 400 meters front crawl events in young swimmers, to model the performance in those events using non-linear mathematic methods through artificial neural networks (multi-layer perceptrons and to assess the neural network models precision to predict the performance. A sample of 138 young swimmers (65 males and 73 females of national level was submitted to a test battery comprising four different domains: kinanthropometric evaluation, dry land functional evaluation (strength and flexibility, swimming functional evaluation (hydrodynamics, hydrostatic and bioenergetics characteristics and swimming technique evaluation. To establish a profile of the young swimmer non-linear combinations between preponderant variables for each gender and swim performance in the 200 meters medley and 400 meters font crawl events were developed. For this purpose a feed forward neural network was used (Multilayer Perceptron with three neurons in a single hidden layer. The prognosis precision of the model (error lower than 0.8% between true and estimated performances is supported by recent evidence. Therefore, we consider that the neural network tool can be a good approach in the resolution of complex problems such as performance modeling and the talent identification in swimming and, possibly, in a wide variety of sports

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

NARCIS (Netherlands)

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

2014-01-01

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

Towards a Social Networks Model for Online Learning & Performance

Science.gov (United States)

Chung, Kon Shing Kenneth; Paredes, Walter Christian

2015-01-01

In this study, we develop a theoretical model to investigate the association between social network properties, "content richness" (CR) in academic learning discourse, and performance. CR is the extent to which one contributes content that is meaningful, insightful and constructive to aid learning and by social network properties we…

A Framework to Implement IoT Network Performance Modelling Techniques for Network Solution Selection.

Science.gov (United States)

Delaney, Declan T; O'Hare, Gregory M P

2016-12-01

No single network solution for Internet of Things (IoT) networks can provide the required level of Quality of Service (QoS) for all applications in all environments. This leads to an increasing number of solutions created to fit particular scenarios. Given the increasing number and complexity of solutions available, it becomes difficult for an application developer to choose the solution which is best suited for an application. This article introduces a framework which autonomously chooses the best solution for the application given the current deployed environment. The framework utilises a performance model to predict the expected performance of a particular solution in a given environment. The framework can then choose an apt solution for the application from a set of available solutions. This article presents the framework with a set of models built using data collected from simulation. The modelling technique can determine with up to 85% accuracy the solution which performs the best for a particular performance metric given a set of solutions. The article highlights the fractured and disjointed practice currently in place for examining and comparing communication solutions and aims to open a discussion on harmonising testing procedures so that different solutions can be directly compared and offers a framework to achieve this within IoT networks.

A Framework to Implement IoT Network Performance Modelling Techniques for Network Solution Selection

Directory of Open Access Journals (Sweden)

Declan T. Delaney

2016-12-01

Full Text Available No single network solution for Internet of Things (IoT networks can provide the required level of Quality of Service (QoS for all applications in all environments. This leads to an increasing number of solutions created to fit particular scenarios. Given the increasing number and complexity of solutions available, it becomes difficult for an application developer to choose the solution which is best suited for an application. This article introduces a framework which autonomously chooses the best solution for the application given the current deployed environment. The framework utilises a performance model to predict the expected performance of a particular solution in a given environment. The framework can then choose an apt solution for the application from a set of available solutions. This article presents the framework with a set of models built using data collected from simulation. The modelling technique can determine with up to 85% accuracy the solution which performs the best for a particular performance metric given a set of solutions. The article highlights the fractured and disjointed practice currently in place for examining and comparing communication solutions and aims to open a discussion on harmonising testing procedures so that different solutions can be directly compared and offers a framework to achieve this within IoT networks.

Predicting Expressive Dynamics in Piano Performances using Neural Networks

NARCIS (Netherlands)

van Herwaarden, Sam; Grachten, Maarten; de Haas, W. Bas

2014-01-01

This paper presents a model for predicting expressive accentuation in piano performances with neural networks. Using Restricted Boltzmann Machines (RBMs), features are learned from performance data, after which these features are used to predict performed loudness. During feature learning, data

A Fluid Model for Performance Analysis in Cellular Networks

Directory of Open Access Journals (Sweden)

Coupechoux Marceau

2010-01-01

Full Text Available We propose a new framework to study the performance of cellular networks using a fluid model and we derive from this model analytical formulas for interference, outage probability, and spatial outage probability. The key idea of the fluid model is to consider the discrete base station (BS entities as a continuum of transmitters that are spatially distributed in the network. This model allows us to obtain simple analytical expressions to reveal main characteristics of the network. In this paper, we focus on the downlink other-cell interference factor (OCIF, which is defined for a given user as the ratio of its outer cell received power to its inner cell received power. A closed-form formula of the OCIF is provided in this paper. From this formula, we are able to obtain the global outage probability as well as the spatial outage probability, which depends on the location of a mobile station (MS initiating a new call. Our analytical results are compared to Monte Carlo simulations performed in a traditional hexagonal network. Furthermore, we demonstrate an application of the outage probability related to cell breathing and densification of cellular networks.

Deep Recurrent Convolutional Neural Network: Improving Performance For Speech Recognition

OpenAIRE

Zhang, Zewang; Sun, Zheng; Liu, Jiaqi; Chen, Jingwen; Huo, Zhao; Zhang, Xiao

2016-01-01

A deep learning approach has been widely applied in sequence modeling problems. In terms of automatic speech recognition (ASR), its performance has significantly been improved by increasing large speech corpus and deeper neural network. Especially, recurrent neural network and deep convolutional neural network have been applied in ASR successfully. Given the arising problem of training speed, we build a novel deep recurrent convolutional network for acoustic modeling and then apply deep resid...

A general framework for performance guaranteed green data center networking

OpenAIRE

Wang, Ting; Xia, Yu; Muppala, Jogesh; Hamdi, Mounir; Foufou, Sebti

2014-01-01

From the perspective of resource allocation and routing, this paper aims to save as much energy as possible in data center networks. We present a general framework, based on the blocking island paradigm, to try to maximize the network power conservation and minimize sacrifices of network performance and reliability. The bandwidth allocation mechanism together with power-aware routing algorithm achieve a bandwidth guaranteed tighter network. Besides, our fast efficient heuristics for allocatin...

LTE Adaptation for Mobile Broadband Satellite Networks

Directory of Open Access Journals (Sweden)

Bastia Francesco

2009-01-01

Full Text Available One of the key factors for the successful deployment of mobile satellite systems in 4G networks is the maximization of the technology commonalities with the terrestrial systems. An effective way of achieving this objective consists in considering the terrestrial radio interface as the baseline for the satellite radio interface. Since the 3GPP Long Term Evolution (LTE standard will be one of the main players in the 4G scenario, along with other emerging technologies, such as mobile WiMAX; this paper analyzes the possible applicability of the 3GPP LTE interface to satellite transmission, presenting several enabling techniques for this adaptation. In particular, we propose the introduction of an inter-TTI interleaving technique that exploits the existing H-ARQ facilities provided by the LTE physical layer, the use of PAPR reduction techniques to increase the resilience of the OFDM waveform to non linear distortion, and the design of the sequences for Random Access, taking into account the requirements deriving from the large round trip times. The outcomes of this analysis show that, with the required proposed enablers, it is possible to reuse the existing terrestrial air interface to transmit over the satellite link.

Social networks and small businesses performance in West African border regions

DEFF Research Database (Denmark)

Kuépié, Mathias; Tenikue, Michel; Walther, Olivier

2016-01-01

burden that leads to a negative economic impact. Testing the effect of social networks between small traders and three categories of actors, we find that the most well-connected actors are also the most successful in terms of monthly profit. The effects of social networks are, however, dependent...... with traditional religious leaders has a negative effect on economic performance. Our work has two implications: first, collecting data on social networks remains challenging due to endogeneity. Second, network-enhancing policies should aim at improving both the internal connectivity of economic actors......This paper studies the link between economic performance and social networks in West Africa. Using data collected about 358 small-scale traders in five border markets, we show that social network can simultaneously be a resource which positively contributes to labor market outcomes and a social...

A performance analysis of DS-CDMA and SCPC VSAT networks

Science.gov (United States)

Hayes, David P.; Ha, Tri T.

1990-01-01

Spread-spectrum and single-channel-per-carrier (SCPC) transmission techniques work well in very small aperture terminal (VSAT) networks for multiple-access purposes while allowing the earth station antennas to remain small. Direct-sequence code-division multiple-access (DS-CDMA) is the simplest spread-spectrum technique to use in a VSAT network since a frequency synthesizer is not required for each terminal. An examination is made of the DS-CDMA and SCPC Ku-band VSAT satellite systems for low-density (64-kb/s or less) communications. A method for improving the standardf link analysis of DS-CDMA satellite-switched networks by including certain losses is developed. The performance of 50-channel full mesh and star network architectures is analyzed. The selection of operating conditions producing optimum performance is demonstrated.

Investigation of road network features and safety performance.

Science.gov (United States)

Wang, Xuesong; Wu, Xingwei; Abdel-Aty, Mohamed; Tremont, Paul J

2013-07-01

The analysis of road network designs can provide useful information to transportation planners as they seek to improve the safety of road networks. The objectives of this study were to compare and define the effective road network indices and to analyze the relationship between road network structure and traffic safety at the level of the Traffic Analysis Zone (TAZ). One problem in comparing different road networks is establishing criteria that can be used to scale networks in terms of their structures. Based on data from Orange and Hillsborough Counties in Florida, road network structural properties within TAZs were scaled using 3 indices: Closeness Centrality, Betweenness Centrality, and Meshedness Coefficient. The Meshedness Coefficient performed best in capturing the structural features of the road network. Bayesian Conditional Autoregressive (CAR) models were developed to assess the safety of various network configurations as measured by total crashes, crashes on state roads, and crashes on local roads. The models' results showed that crash frequencies on local roads were closely related to factors within the TAZs (e.g., zonal network structure, TAZ population), while crash frequencies on state roads were closely related to the road and traffic features of state roads. For the safety effects of different networks, the Grid type was associated with the highest frequency of crashes, followed by the Mixed type, the Loops & Lollipops type, and the Sparse type. This study shows that it is possible to develop a quantitative scale for structural properties of a road network, and to use that scale to calculate the relationships between network structural properties and safety. Copyright © 2013 Elsevier Ltd. All rights reserved.

Interactive multicentre teleconferences using open source software in a team of thoracic surgeons.

Science.gov (United States)

Ito, Kazuhiro; Shimada, Junichi; Katoh, Daishiro; Nishimura, Motohiro; Yanada, Masashi; Okada, Satoru; Ishihara, Shunta; Ichise, Kaori

2012-12-01

Real-time consultation between a team of thoracic surgeons is important for the management of difficult cases. We established a system for interactive teleconsultation between multiple sites, based on open-source software. The graphical desktop-sharing system VNC (virtual network computing) was used for remotely controlling another computer. An image-processing package (OsiriX) was installed on the server to share the medical images. We set up a voice communication system using Voice Chatter, a free, cross-platform voice communication application. Four hospitals participated in the trials. One was connected by gigabit ethernet, one by WiMAX and one by ADSL. Surgeons at three of the sites found that it was comfortable to view images and consult with each other using the teleconferencing system. However, it was not comfortable using the client that connected via WiMAX, because of dropped frames. Apart from the WiMAX connection, the VNC-based screen-sharing system transferred the clinical images efficiently and in real time. We found the screen-sharing software VNC to be a good application for medical image interpretation, especially for a team of thoracic surgeons using multislice CT scans.

A performance study of unmanned aerial vehicle-based sensor networks under cyber attack

Science.gov (United States)

Puchaty, Ethan M.

In UAV-based sensor networks, an emerging area of interest is the performance of these networks under cyber attack. This study seeks to evaluate the performance trade-offs from a System-of-Systems (SoS) perspective between various UAV communications architecture options in the context two missions: tracking ballistic missiles and tracking insurgents. An agent-based discrete event simulation is used to model a sensor communication network consisting of UAVs, military communications satellites, ground relay stations, and a mission control center. Network susceptibility to cyber attack is modeled with probabilistic failures and induced data variability, with performance metrics focusing on information availability, latency, and trustworthiness. Results demonstrated that using UAVs as routers increased network availability with a minimal latency penalty and communications satellite networks were best for long distance operations. Redundancy in the number of links between communication nodes helped mitigate cyber-caused link failures and add robustness in cases of induced data variability by an adversary. However, when failures were not independent, redundancy and UAV routing were detrimental in some cases to network performance. Sensitivity studies indicated that long cyber-caused downtimes and increasing failure dependencies resulted in build-ups of failures and caused significant degradations in network performance.

On the Tradeoff between Performance and Programmability for Software Defined WiFi Networks

Directory of Open Access Journals (Sweden)

Tausif Zahid

2018-01-01

Full Text Available WiFi has become one of the major network access networks due to its simple technical implementation and high-bandwidth provisioning. In this paper, we studied software defined WiFi networks (SDWN against traditional WiFi networks to understand the potential benefits, such as the ability of SDWN to effectively hide the handover delay between access points (AP of the adoption of the SDWN architecture on WiFi networks and identify representative application scenarios where such SDWN approach could bring additional benefits. This study delineated the performance bottlenecks such as the throughput degradation by around 50% compared with the conventional WiFi networks. In addition, our study also shed some insights into performance optimization issues. All of the performance measurements were conducted on a network testbed consisting of a single basic service set (BSS and an extended service set (ESS managed by a single SDN controller deployed with various laboratory settings. Our evaluation included the throughput performance under different traffic loads with different number of nodes and packet sizes for both TCP and UDP traffic flows. Handover delays were measured during the roaming phase between different APs against the traditional WiFi networks. Our results have demonstrated the tradeoff between performance and programmability of software defined APs.

Is functional integration of resting state brain networks an unspecific biomarker for working memory performance?

Science.gov (United States)

Alavash, Mohsen; Doebler, Philipp; Holling, Heinz; Thiel, Christiane M; Gießing, Carsten

2015-03-01

Is there one optimal topology of functional brain networks at rest from which our cognitive performance would profit? Previous studies suggest that functional integration of resting state brain networks is an important biomarker for cognitive performance. However, it is still unknown whether higher network integration is an unspecific predictor for good cognitive performance or, alternatively, whether specific network organization during rest predicts only specific cognitive abilities. Here, we investigated the relationship between network integration at rest and cognitive performance using two tasks that measured different aspects of working memory; one task assessed visual-spatial and the other numerical working memory. Network clustering, modularity and efficiency were computed to capture network integration on different levels of network organization, and to statistically compare their correlations with the performance in each working memory test. The results revealed that each working memory aspect profits from a different resting state topology, and the tests showed significantly different correlations with each of the measures of network integration. While higher global network integration and modularity predicted significantly better performance in visual-spatial working memory, both measures showed no significant correlation with numerical working memory performance. In contrast, numerical working memory was superior in subjects with highly clustered brain networks, predominantly in the intraparietal sulcus, a core brain region of the working memory network. Our findings suggest that a specific balance between local and global functional integration of resting state brain networks facilitates special aspects of cognitive performance. In the context of working memory, while visual-spatial performance is facilitated by globally integrated functional resting state brain networks, numerical working memory profits from increased capacities for local processing

Network Congestion and Performance Management

OpenAIRE

Shewmaker, Andrew Glenn

2016-01-01

We increasingly depend on well-behaved networks in the course of every-day activities for business, community, government, science, and recreation. And with more people demanding a greater variety of services comes sharp disagreement about which needs are most important. Unfortunately, today’s technology is inadequate to guarantee the performance of dynamic and diverse workloads in such a way that we are prevented from hurting each other’s goals.No one likes waiting in traffic, whether on a r...

Performance evaluation of spatial vector routing protocol for wireless sensor networks

International Nuclear Information System (INIS)

Baloch, J.; Jokhio, I.

2012-01-01

WSNs (Wireless Sensor Networks) is an emerging area of research. Researchers worldwide are working on the issues faced by sensor nodes. Communication has been a major issue in wireless networks and the problem is manifolds in WSN s because of the limited resources. The routing protocol in such networks plays a pivotal role, as an effective routing protocol could significantly reduce the energy consumed in transmitting and receiving data packets throughout a network. In this paper the performance of SVR (Spatial Vector Routing) an energy efficient, location aware routing protocol is compared with the existing location aware protocols. The results from the simulation trials show the performance of SVR. (author)

Performance Evaluation of Spatial Vector Routing Protocol for Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Javed Ali Baloch

2012-10-01

Full Text Available WSNs (Wireless Sensor Networks is an emerging area of research. Researchers worldwide are working on the issues faced by sensor nodes. Communication has been a major issue in wireless networks and the problem is manifolds in WSNs because of the limited resources. The routing protocol in such networks plays a pivotal role, as an effective routing protocol could significantly reduce the energy consumed in transmitting and receiving data packets throughout a network. In this paper the performance of SVR (Spatial Vector Routing an energy efficient, location aware routing protocol is compared with the existing location aware protocols. The results from the simulation trials show the performance of SVR.

Effects of the bipartite structure of a network on performance of recommenders

Science.gov (United States)

Wang, Qing-Xian; Li, Jian; Luo, Xin; Xu, Jian-Jun; Shang, Ming-Sheng

2018-02-01

Recommender systems aim to predict people's preferences for online items by analyzing their historical behaviors. A recommender can be modeled as a high-dimensional and sparse bipartite network, where the key issue is to understand the relation between the network structure and a recommender's performance. To address this issue, we choose three network characteristics, clustering coefficient, network density and user-item ratio, as the analyzing targets. For the cluster coefficient, we adopt the Degree-preserving rewiring algorithm to obtain a series of bipartite network with varying cluster coefficient, while the degree of user and item keep unchanged. Furthermore, five state-of-the-art recommenders are applied on two real datasets. The performances of recommenders are measured by both numerical and physical metrics. These results show that a recommender's performance is positively related to the clustering coefficient of a bipartite network. Meanwhile, higher density of a bipartite network can provide more accurate but less diverse or novel recommendations. Furthermore, the user-item ratio is positively correlated with the accuracy metrics but negatively correlated with the diverse and novel metrics.

Performance of highly connected photonic switching lossless metro-access optical networks

Science.gov (United States)

Martins, Indayara Bertoldi; Martins, Yara; Barbosa, Felipe Rudge

2018-03-01

The present work analyzes the performance of photonic switching networks, optical packet switching (OPS) and optical burst switching (OBS), in mesh topology of different sizes and configurations. The "lossless" photonic switching node is based on a semiconductor optical amplifier, demonstrated and validated with experimental results on optical power gain, noise figure, and spectral range. The network performance was evaluated through computer simulations based on parameters such as average number of hops, optical packet loss fraction, and optical transport delay (Am). The combination of these elements leads to a consistent account of performance, in terms of network traffic and packet delivery for OPS and OBS metropolitan networks. Results show that a combination of highly connected mesh topologies having an ingress e-buffer present high efficiency and throughput, with very low packet loss and low latency, ensuring fast data delivery to the final receiver.

Communication, opponents, and clan performance in online games: a social network approach.

Science.gov (United States)

Lee, Hong Joo; Choi, Jaewon; Kim, Jong Woo; Park, Sung Joo; Gloor, Peter

2013-12-01

Online gamers form clans voluntarily to play together and to discuss their real and virtual lives. Although these clans have diverse goals, they seek to increase their rank in the game community by winning more battles. Communications among clan members and battles with other clans may influence the performance of a clan. In this study, we compared the effects of communication structure inside a clan, and battle networks among clans, with the performance of the clans. We collected battle histories, posts, and comments on clan pages from a Korean online game, and measured social network indices for communication and battle networks. Communication structures in terms of density and group degree centralization index had no significant association with clan performance. However, the centrality of clans in the battle network was positively related to the performance of the clan. If a clan had many battle opponents, the performance of the clan improved.

Applying a social network analysis (SNA) approach to understanding radiologists' performance in reading mammograms

Science.gov (United States)

Tavakoli Taba, Seyedamir; Hossain, Liaquat; Heard, Robert; Brennan, Patrick; Lee, Warwick; Lewis, Sarah

2017-03-01

Rationale and objectives: Observer performance has been widely studied through examining the characteristics of individuals. Applying a systems perspective, while understanding of the system's output, requires a study of the interactions between observers. This research explains a mixed methods approach to applying a social network analysis (SNA), together with a more traditional approach of examining personal/ individual characteristics in understanding observer performance in mammography. Materials and Methods: Using social networks theories and measures in order to understand observer performance, we designed a social networks survey instrument for collecting personal and network data about observers involved in mammography performance studies. We present the results of a study by our group where 31 Australian breast radiologists originally reviewed 60 mammographic cases (comprising of 20 abnormal and 40 normal cases) and then completed an online questionnaire about their social networks and personal characteristics. A jackknife free response operating characteristic (JAFROC) method was used to measure performance of radiologists. JAFROC was tested against various personal and network measures to verify the theoretical model. Results: The results from this study suggest a strong association between social networks and observer performance for Australian radiologists. Network factors accounted for 48% of variance in observer performance, in comparison to 15.5% for the personal characteristics for this study group. Conclusion: This study suggest a strong new direction for research into improving observer performance. Future studies in observer performance should consider social networks' influence as part of their research paradigm, with equal or greater vigour than traditional constructs of personal characteristics.

Full-Duplex MIMO Small-Cell Networks: Performance Analysis

OpenAIRE

Atzeni, Italo; Kountouris, Marios

2015-01-01

Full-duplex small-cell relays with multiple antennas constitute a core element of the envisioned 5G network architecture. In this paper, we use stochastic geometry to analyze the performance of wireless networks with full-duplex multiple-antenna small cells, with particular emphasis on the probability of successful transmission. To achieve this goal, we additionally characterize the distribution of the self-interference power of the full-duplex nodes. The proposed framework reveals useful ins...

Artificial neural network simulation of battery performance

Energy Technology Data Exchange (ETDEWEB)

O`Gorman, C.C.; Ingersoll, D.; Jungst, R.G.; Paez, T.L.

1998-12-31

Although they appear deceptively simple, batteries embody a complex set of interacting physical and chemical processes. While the discrete engineering characteristics of a battery such as the physical dimensions of the individual components, are relatively straightforward to define explicitly, their myriad chemical and physical processes, including interactions, are much more difficult to accurately represent. Within this category are the diffusive and solubility characteristics of individual species, reaction kinetics and mechanisms of primary chemical species as well as intermediates, and growth and morphology characteristics of reaction products as influenced by environmental and operational use profiles. For this reason, development of analytical models that can consistently predict the performance of a battery has only been partially successful, even though significant resources have been applied to this problem. As an alternative approach, the authors have begun development of a non-phenomenological model for battery systems based on artificial neural networks. Both recurrent and non-recurrent forms of these networks have been successfully used to develop accurate representations of battery behavior. The connectionist normalized linear spline (CMLS) network has been implemented with a self-organizing layer to model a battery system with the generalized radial basis function net. Concurrently, efforts are under way to use the feedforward back propagation network to map the {open_quotes}state{close_quotes} of a battery system. Because of the complexity of battery systems, accurate representation of the input and output parameters has proven to be very important. This paper describes these initial feasibility studies as well as the current models and makes comparisons between predicted and actual performance.

Evaluating Flight Crew Performance by a Bayesian Network Model

Directory of Open Access Journals (Sweden)

Wei Chen

2018-03-01

Full Text Available Flight crew performance is of great significance in keeping flights safe and sound. When evaluating the crew performance, quantitative detailed behavior information may not be available. The present paper introduces the Bayesian Network to perform flight crew performance evaluation, which permits the utilization of multidisciplinary sources of objective and subjective information, despite sparse behavioral data. In this paper, the causal factors are selected based on the analysis of 484 aviation accidents caused by human factors. Then, a network termed Flight Crew Performance Model is constructed. The Delphi technique helps to gather subjective data as a supplement to objective data from accident reports. The conditional probabilities are elicited by the leaky noisy MAX model. Two ways of inference for the BN—probability prediction and probabilistic diagnosis are used and some interesting conclusions are drawn, which could provide data support to make interventions for human error management in aviation safety.

NetBench. Automated Network Performance Testing

CERN Document Server

Cadeddu, Mattia

2016-01-01

In order to evaluate the operation of high performance routers, CERN has developed the NetBench software to run benchmarking tests by injecting various traffic patterns and observing the network devices behaviour in real-time. The tool features a modular design with a Python based console used to inject traffic and collect the results in a database, and a web user

Outage and ser performance of an opportunistic multi-user underlay cognitive network

KAUST Repository

Khan, Fahd Ahmed

2012-10-01

Consider a multi-user underlay cognitive network where multiple cognitive users concurrently share the spectrum with a primary network and a single secondary user is selected for transmission. The channel is assumed to have independent but not identical Nakagami-m fading. Closed form expressions for the outage performance and the symbol-error-rate performance of the opportunistic multi-user secondary network are derived when a peak interference power constraint is imposed on the secondary network in addition to the limited peak transmit power of each secondary user. © 2012 IEEE.

Coexistence: Threat to the Performance of Heterogeneous Network

Science.gov (United States)

Sharma, Neetu; Kaur, Amanpreet

2010-11-01

Wireless technology is gaining broad acceptance as users opt for the freedom that only wireless network can provide. Well-accepted wireless communication technologies generally operate in frequency bands that are shared among several users, often using different RF schemes. This is true in particular for WiFi, Bluetooth, and more recently ZigBee. These all three operate in the unlicensed 2.4 GHz band, also known as ISM band, which has been key to the development of a competitive and innovative market for wireless embedded devices. But, as with any resource held in common, it is crucial that those technologies coexist peacefully to allow each user of the band to fulfill its communication goals. This has led to an increase in wireless devices intended for use in IEEE 802.11 wireless local area networks (WLANs) and wireless personal area networks (WPANs), both of which support operation in the crowded 2.4-GHz industrial, scientific and medical (ISM) band. Despite efforts made by standardization bodies to ensure smooth coexistence it may occur that communication technologies transmitting for instance at very different power levels interfere with each other. In particular, it has been pointed out that ZigBee could potentially experience interference from WiFi traffic given that while both protocols can transmit on the same channel, WiFi transmissions usually occur at much higher power level. In this work, we considered a heterogeneous network and analyzed the impact of coexistence between IEEE 802.15.4 and IEEE 802.11b. To evaluate the performance of this network, measurement and simulation study are conducted and developed in the QualNet Network simulator, version 5.0.Model is analyzed for different placement models or topologies such as Random. Grid & Uniform. Performance is analyzed on the basis of characteristics such as throughput, average jitter and average end to end delay. Here, the impact of varying different antenna gain & shadowing model for this

Topology and computational performance of attractor neural networks

International Nuclear Information System (INIS)

McGraw, Patrick N.; Menzinger, Michael

2003-01-01

To explore the relation between network structure and function, we studied the computational performance of Hopfield-type attractor neural nets with regular lattice, random, small-world, and scale-free topologies. The random configuration is the most efficient for storage and retrieval of patterns by the network as a whole. However, in the scale-free case retrieval errors are not distributed uniformly among the nodes. The portion of a pattern encoded by the subset of highly connected nodes is more robust and efficiently recognized than the rest of the pattern. The scale-free network thus achieves a very strong partial recognition. The implications of these findings for brain function and social dynamics are suggestive

The Impact of Social Networks on Students’ Performance

Directory of Open Access Journals (Sweden)

Jusuf Zekiri

2016-11-01

Full Text Available The objective of this study is to determine the impact of using social media and its impact on students’ performance and success. This research tries to identify the relationship between students’ use of social networks and their success in their studies. It tries also to find out whether time spent impacts students’ performance and success. Whether students use social media more for entertainment or for teaching and information sharing purposes. The paper uses a quantitative approach for collecting the primary data. The data was collected by surveying 255 respondents from South East European University. The data analyses were done by SPSS so" ware program. Cronbach alpha is used for testing the validity and reliability of variables used in this study. The hypotheses were tested using One Simple T-test. The obtained empirical results show that a great number of students are aware of advantages and disadvantages by the social media. Thus, due to a great percent of times spent on social networking activities, the performance and the success of students suffer setbacks which could lead to a poor performance and they might fail to create a balance between the social media and academic activities. Furthermore, it is about their addiction, the loss of time leading to consequences in their academic development, and they are also influenced to a great extent negatively by the social networking sites, because their attention is focused on chatting and music while their academic activities are neglected. Finally, based on the results of survey, we can conclude that impact of social media on the academic performance of students should focus more on the positive side than on the negative side to achieve balance. Hence, creating more pages for research and academic activities will enable students to improve their performance, thereby avoiding a distraction which leads to deviation from their academic work.

Performers and performance : how to investigate the contribution of the operational network to operational performance

NARCIS (Netherlands)

Wijngaard, J.; Vries, J. de; Nauta, A.

2006-01-01

Purpose This paper seeks to explore the question of how to investigate the contribution of the operational network (comprising sales service, logistics, planning, production, etc.) to operational performance. In doing so, the paper aims to link concepts from organisational and social psychology to

Performers and performance : How to investigate the contribution of the operational network to operational performance

NARCIS (Netherlands)

Wijngaard, J.; de Vries, J.; Nauta, Aukje

2006-01-01

Purpose - This paper seeks to explore the question of how to investigate the contribution of the operational network (comprising sales service, logistics, planning, production, etc.) to operational performance. In doing so, the paper aims to link concepts from organisational and social psychology to

Performance analysis of WS-EWC coded optical CDMA networks with/without LDPC codes

Science.gov (United States)

Huang, Chun-Ming; Huang, Jen-Fa; Yang, Chao-Chin

2010-10-01

One extended Welch-Costas (EWC) code family for the wavelength-division-multiplexing/spectral-amplitude coding (WDM/SAC; WS) optical code-division multiple-access (OCDMA) networks is proposed. This system has a superior performance as compared to the previous modified quadratic congruence (MQC) coded OCDMA networks. However, since the performance of such a network is unsatisfactory when the data bit rate is higher, one class of quasi-cyclic low-density parity-check (QC-LDPC) code is adopted to improve that. Simulation results show that the performance of the high-speed WS-EWC coded OCDMA network can be greatly improved by using the LDPC codes.

Performance in wireless networks and industrial wireless networks on control processes in real time under industrial environments

Directory of Open Access Journals (Sweden)

Juan F. Monsalve-Posada

2015-01-01

Full Text Available The growing use of Ethernet networks on the industrial automation pyramid has led many companies to develop new devices to operate in requirements of this level, nowadays it is called Industrial Ethernet network, on the market there are various sensors and actuators to industrial scale equipped with this technology, many of these devices are very expensive. In this paper, the performance of two wireless networks is evaluated, the first network has conventional Ethernet devices, and the second network has Industrial Ethernet devices. For the process we vary four parameters such as distance, number of bytes, the signal to noise ratio, and the packet error rate, and then we measure delays and compare with metric statistics results, Box Plot graphs were used for the analysis. Finally, we conclude that under the parameters and conditions tested, wireless networks can serve as a communication system in control applications with allowable delays of up to 50 ms, in addition, the results show a better performance of Industrial Ethernet networks over conventional networks, with differences in the RTT of milliseconds. Therefore, it is recommended to establish what risk is for the process to control these delays to determine if the equipment conventional applies, since under certain features like humidity and temperature can operate properly for a considerable time and at lower cost than devices to Industrial Ethernet.

The performance evaluation of a new neural network based traffic management scheme for a satellite communication network

Science.gov (United States)

Ansari, Nirwan; Liu, Dequan

1991-01-01

A neural-network-based traffic management scheme for a satellite communication network is described. The scheme consists of two levels of management. The front end of the scheme is a derivation of Kohonen's self-organization model to configure maps for the satellite communication network dynamically. The model consists of three stages. The first stage is the pattern recognition task, in which an exemplar map that best meets the current network requirements is selected. The second stage is the analysis of the discrepancy between the chosen exemplar map and the state of the network, and the adaptive modification of the chosen exemplar map to conform closely to the network requirement (input data pattern) by means of Kohonen's self-organization. On the basis of certain performance criteria, whether a new map is generated to replace the original chosen map is decided in the third stage. A state-dependent routing algorithm, which arranges the incoming call to some proper path, is used to make the network more efficient and to lower the call block rate. Simulation results demonstrate that the scheme, which combines self-organization and the state-dependent routing mechanism, provides better performance in terms of call block rate than schemes that only have either the self-organization mechanism or the routing mechanism.

Evaluation of knowledge management performances in NULIFE network

International Nuclear Information System (INIS)

Nitoi, Mirela; Cojan, Mihai; Pavelescu, Margarit

2009-01-01

One of the objectives of Nuclear Plant Life Prediction (NULIFE) network is the identification of experts and resources which can be used in the future. The major challenge is to use these competent personnel in an efficient manner, in the network. The paper presents the necessity of developing the knowledge management strategy for networks of excellence, as the specific issues of NULIFE network. In order to highlight the progress during the project operating, the developed indicators of performance are specified. The developed questionnaires evaluate the quality of knowledge management (development, use and distribution of knowledge), type of knowledge which is considered important for organization (at present and in future) and the benefits of knowledge transfer (immediate and in perspective). The developed questionnaires permit along with the evaluation of others groups activities, an auto-evaluation for the activity of the group where the subject is involved. (authors)

An evaluation of current high-performance networks

Energy Technology Data Exchange (ETDEWEB)

Bell, Christian; Bonachea, Dan; Cote, Yannick; Duell, Jason; Hargrove, Paul; Husbands, Parry; Iancu, Costin; Welcome, Michael; Yelick, Katherine

2003-01-25

High-end supercomputers are increasingly built out of commodity components, and lack tight integration between the processor and network. This often results in inefficiencies in the communication subsystem, such as high software overheads and/or message latencies. In this paper we use a set of microbenchmarks to quantify the cost of this commoditization, measuring software overhead, latency, and bandwidth on five contemporary supercomputing networks. We compare the performance of the ubiquitous MPI layer to that of lower-level communication layers, and quantify the advantages of the latter for small message performance. We also provide data on the potential for various communication-related optimizations, such as overlapping communication with computation or other communication. Finally, we determine the minimum size needed for a message to be considered 'large' (i.e., bandwidth-bound) on these platforms, and provide historical data on the software overheads of a number of supercomputers over the past decade.

Multicast Performance Analysis for High-Speed Torus Networks

National Research Council Canada - National Science Library

Oral, S; George, A

2002-01-01

... for unicast-based and path-based multicast communication on high-speed torus networks. Software-based multicast performance results of selected algorithms on a 16-node Scalable Coherent Interface (SCI) torus are given...

78 FR 9605 - Operation of Wireless Communications Services in the 2.3 GHz Band; Establishment of Rules and...

Science.gov (United States)

2013-02-11

... should be measured over a 5 ms frame; for WCS networks using LTE technology, the duty cycle should be measured over a 10 ms frame. For TDD technologies other than LTE and WiMAX, the duty cycle should be... Long Term Evolution (3GPP LTE); Denied a petition requesting further restrictions on WCS mobile and...

Performance and complexity of tunable sparse network coding with gradual growing tuning functions over wireless networks

OpenAIRE

Garrido Ortiz, Pablo; Sørensen, Chres W.; Lucani Roetter, Daniel Enrique; Agüero Calvo, Ramón

2016-01-01

Random Linear Network Coding (RLNC) has been shown to be a technique with several benefits, in particular when applied over wireless mesh networks, since it provides robustness against packet losses. On the other hand, Tunable Sparse Network Coding (TSNC) is a promising concept, which leverages a trade-off between computational complexity and goodput. An optimal density tuning function has not been found yet, due to the lack of a closed-form expression that links density, performance and comp...

Visualizing weighted networks: a performance comparison of adjacency matrices versus node-link diagrams

Science.gov (United States)

McIntire, John P.; Osesina, O. Isaac; Bartley, Cecilia; Tudoreanu, M. Eduard; Havig, Paul R.; Geiselman, Eric E.

2012-06-01

Ensuring the proper and effective ways to visualize network data is important for many areas of academia, applied sciences, the military, and the public. Fields such as social network analysis, genetics, biochemistry, intelligence, cybersecurity, neural network modeling, transit systems, communications, etc. often deal with large, complex network datasets that can be difficult to interact with, study, and use. There have been surprisingly few human factors performance studies on the relative effectiveness of different graph drawings or network diagram techniques to convey information to a viewer. This is particularly true for weighted networks which include the strength of connections between nodes, not just information about which nodes are linked to other nodes. We describe a human factors study in which participants performed four separate network analysis tasks (finding a direct link between given nodes, finding an interconnected node between given nodes, estimating link strengths, and estimating the most densely interconnected nodes) on two different network visualizations: an adjacency matrix with a heat-map versus a node-link diagram. The results should help shed light on effective methods of visualizing network data for some representative analysis tasks, with the ultimate goal of improving usability and performance for viewers of network data displays.

The enhancing impact of friendship networks on sales managers' performance

OpenAIRE

Claro, Danny Pimentel; Laban Neto, Silvio Abrahão; Claro, Priscila Borin de Oliveira

2013-01-01

This paper examines how relationships with friends moderate the impact of professional networks on sales performance. Based on a sample of 204 sales managers in a professional service company, this study presents evidence that friendship networks amplify the effect of sales forces’ professional networks on new product sales as well as on prospecting and converting new deals. Our results offer important insights into the socio-cognitive perspective of sales management literature and suggest th...

Evaluating the Impact of Communication Network Performance on Supervisory Supermarket Control

DEFF Research Database (Denmark)

Madsen, Jacob Theilgaard; Minko, Tomasz; Madsen, Tatiana Kozlova

2017-01-01

This paper addresses the evaluation of the impact of non-ideal communication networks on system performance of hierarchical control systems. It develops a stepwise evaluation approach that is applied to the example scenario of a supervisory controller for supermarket temperature control, addressing...... of communication network performance on the supermarket refrigeration control and resulting energy costs using simulation models. The results show that the controller is resilient to downstream information delays, however upstream delays or up- and downstream information loss can cause significant performance...

LEARNING ALGORITHM EFFECT ON MULTILAYER FEED FORWARD ARTIFICIAL NEURAL NETWORK PERFORMANCE IN IMAGE CODING

Directory of Open Access Journals (Sweden)

OMER MAHMOUD

2007-08-01

Full Text Available One of the essential factors that affect the performance of Artificial Neural Networks is the learning algorithm. The performance of Multilayer Feed Forward Artificial Neural Network performance in image compression using different learning algorithms is examined in this paper. Based on Gradient Descent, Conjugate Gradient, Quasi-Newton techniques three different error back propagation algorithms have been developed for use in training two types of neural networks, a single hidden layer network and three hidden layers network. The essence of this study is to investigate the most efficient and effective training methods for use in image compression and its subsequent applications. The obtained results show that the Quasi-Newton based algorithm has better performance as compared to the other two algorithms.

The Gain of Performance of Optical WDM Networks

Directory of Open Access Journals (Sweden)

Miroslav Bahleda

2008-01-01

Full Text Available We study the blocking probability and performance of single-fiber and multifiber optical networks with wavelength division multiplexing (WDM. We extend the well-known analytical blocking probability model by Barry and Humblet to the general model, which is proposed for both single-fiber and multifiber network paths with any kind of wavelength conversion (no, limited, or full wavelength conversion and for uniform and nonuniform link loads. We investigate the effect of the link load, wavelength conversion degree, and the number of wavelengths, fibers, and hops on blocking probability. We also extend the definition of the gain of wavelength conversion by Barry and Humblet to the gain of performance, which is fully general. Thanks to this definition and implementation of our model, we compare different WDM node architectures and present interesting results.

Performance of social network sensors during Hurricane Sandy.

Directory of Open Access Journals (Sweden)

Yury Kryvasheyeu

Full Text Available Information flow during catastrophic events is a critical aspect of disaster management. Modern communication platforms, in particular online social networks, provide an opportunity to study such flow and derive early-warning sensors, thus improving emergency preparedness and response. Performance of the social networks sensor method, based on topological and behavioral properties derived from the "friendship paradox", is studied here for over 50 million Twitter messages posted before, during, and after Hurricane Sandy. We find that differences in users' network centrality effectively translate into moderate awareness advantage (up to 26 hours; and that geo-location of users within or outside of the hurricane-affected area plays a significant role in determining the scale of such an advantage. Emotional response appears to be universal regardless of the position in the network topology, and displays characteristic, easily detectable patterns, opening a possibility to implement a simple "sentiment sensing" technique that can detect and locate disasters.

Performance of Social Network Sensors during Hurricane Sandy

Science.gov (United States)

Kryvasheyeu, Yury; Chen, Haohui; Moro, Esteban; Van Hentenryck, Pascal; Cebrian, Manuel

2015-01-01

Information flow during catastrophic events is a critical aspect of disaster management. Modern communication platforms, in particular online social networks, provide an opportunity to study such flow and derive early-warning sensors, thus improving emergency preparedness and response. Performance of the social networks sensor method, based on topological and behavioral properties derived from the “friendship paradox”, is studied here for over 50 million Twitter messages posted before, during, and after Hurricane Sandy. We find that differences in users’ network centrality effectively translate into moderate awareness advantage (up to 26 hours); and that geo-location of users within or outside of the hurricane-affected area plays a significant role in determining the scale of such an advantage. Emotional response appears to be universal regardless of the position in the network topology, and displays characteristic, easily detectable patterns, opening a possibility to implement a simple “sentiment sensing” technique that can detect and locate disasters. PMID:25692690

The Impact of Increases in Subsidiary Autonomy and Network Relationships on Performance

DEFF Research Database (Denmark)

Gammelgaard, Jens; McDonald, Frank; Stephan, Andreas

2012-01-01

This paper uses network approaches to subsidiary theory to investigate the performance impacts of interactions among the factors of autonomy, intra-organizational network relationships, and inter-organizational network relationships. The paper offers an analysis of both direct and indirect intera...

A Holistic Approach to ZigBee Performance Enhancement for Home Automation Networks

Directory of Open Access Journals (Sweden)

August Betzler

2014-08-01

Full Text Available Wireless home automation networks are gaining importance for smart homes. In this ambit, ZigBee networks play an important role. The ZigBee specification defines a default set of protocol stack parameters and mechanisms that is further refined by the ZigBee Home Automation application profile. In a holistic approach, we analyze how the network performance is affected with the tuning of parameters and mechanisms across multiple layers of the ZigBee protocol stack and investigate possible performance gains by implementing and testing alternative settings. The evaluations are carried out in a testbed of 57 TelosB motes. The results show that considerable performance improvements can be achieved by using alternative protocol stack configurations. From these results, we derive two improved protocol stack configurations for ZigBee wireless home automation networks that are validated in various network scenarios. In our experiments, these improved configurations yield a relative packet delivery ratio increase of up to 33.6%, a delay decrease of up to 66.6% and an improvement of the energy efficiency for battery powered devices of up to 48.7%, obtainable without incurring any overhead to the network.

A Holistic Approach to ZigBee Performance Enhancement for Home Automation Networks

Science.gov (United States)

Betzler, August; Gomez, Carles; Demirkol, Ilker; Paradells, Josep

2014-01-01

Wireless home automation networks are gaining importance for smart homes. In this ambit, ZigBee networks play an important role. The ZigBee specification defines a default set of protocol stack parameters and mechanisms that is further refined by the ZigBee Home Automation application profile. In a holistic approach, we analyze how the network performance is affected with the tuning of parameters and mechanisms across multiple layers of the ZigBee protocol stack and investigate possible performance gains by implementing and testing alternative settings. The evaluations are carried out in a testbed of 57 TelosB motes. The results show that considerable performance improvements can be achieved by using alternative protocol stack configurations. From these results, we derive two improved protocol stack configurations for ZigBee wireless home automation networks that are validated in various network scenarios. In our experiments, these improved configurations yield a relative packet delivery ratio increase of up to 33.6%, a delay decrease of up to 66.6% and an improvement of the energy efficiency for battery powered devices of up to 48.7%, obtainable without incurring any overhead to the network. PMID:25196004

A holistic approach to ZigBee performance enhancement for home automation networks.

Science.gov (United States)

Betzler, August; Gomez, Carles; Demirkol, Ilker; Paradells, Josep

2014-08-14

Wireless home automation networks are gaining importance for smart homes. In this ambit, ZigBee networks play an important role. The ZigBee specification defines a default set of protocol stack parameters and mechanisms that is further refined by the ZigBee Home Automation application profile. In a holistic approach, we analyze how the network performance is affected with the tuning of parameters and mechanisms across multiple layers of the ZigBee protocol stack and investigate possible performance gains by implementing and testing alternative settings. The evaluations are carried out in a testbed of 57 TelosB motes. The results show that considerable performance improvements can be achieved by using alternative protocol stack configurations. From these results, we derive two improved protocol stack configurations for ZigBee wireless home automation networks that are validated in various network scenarios. In our experiments, these improved configurations yield a relative packet delivery ratio increase of up to 33.6%, a delay decrease of up to 66.6% and an improvement of the energy efficiency for battery powered devices of up to 48.7%, obtainable without incurring any overhead to the network.

Strategy for tactical cellular connectivity

Science.gov (United States)

Carlson, Frederick R.

2011-06-01

This paper proposes a strategy to unify four disparate networks under an Internet Protocol (IP) umbrella. The first network is the Army Warfighter Information Network - Tactical (WIN-T) area common user system. The second network is an extension to the area common user system using the Mobile Ad Hoc Interoperability Networking Gateway (MAINGATE) system. The third network is the Worldwide Interoperability for Microwave Access (WiMax) based wireless access network and the forth network is the 802.11 WiFi Network. It is the intent of this paper to propose a skeletal wireless strategy that at its core will create everything over IP (EoIP) and "Everything over IEEE" ("EoIEEE") standards at the tactical level of the battlefield.

NM-Net Gigabit-based Implementation on Core Network Facilities and Performance Design Hierarchy

International Nuclear Information System (INIS)

Raja Murzaferi Raja Moktar; Mohd Fauzi Haris; Siti Nurbahyah Hamdan

2013-01-01

Nuclear Malaysia computing network or NM-net has been gradually developed since 1990s. Since then it has been the main backbone of inter networking on agency's IT infrastructure, serving users ranging from researchers to operational staffs. Main network operating center or NOC is situated in Block 15 and linkup via fiber or UTP cabling to adjacent main network blocks (18, 29, 11 and 44-Dengkil) and later to other blocks enabling network connections. In 2009 the main core network has been built up form several switches up link to form the main networking switch, while on the adjacent main block networks are mainly based on fast Ethernet technology . With current research and operational tasks highly dependent on IT infrastructure that is being enabled through NM-Net, the performance of the infrastructure are most critical. This paper will discuss NM-Net implementing gigabit-based networking system and performance network design hierarchy in order to achieve highest availability of inter networking services in the agency thus catalyzing Nuclear Malaysia future research initiative. (author)

The establishment of heterogeneous networks in performative spaces

DEFF Research Database (Denmark)

Suenson, Valinka; Harder, Henrik

2010-01-01

This paper presents an empirical research combining the Actor Network Theory with a development of RFID (Radio Frequency Identification) technology for tracking indoor movement behavior. The aim of the paper is to disucss the value of RFID technology as a method for observing heterogeneous networks...... and architecture through this theoretical perspective, it highlights the importance of the user involvement in the performative spaces where materiality becomes an actant on equal terms with the users. This paper discusses the use of RFID technology for tracking indoor movenment behavior as a method for examining...

Enhanced memory performance thanks to neural network assortativity

International Nuclear Information System (INIS)

Franciscis, S. de; Johnson, S.; Torres, J. J.

2011-01-01

The behaviour of many complex dynamical systems has been found to depend crucially on the structure of the underlying networks of interactions. An intriguing feature of empirical networks is their assortativity--i.e., the extent to which the degrees of neighbouring nodes are correlated. However, until very recently it was difficult to take this property into account analytically, most work being exclusively numerical. We get round this problem by considering ensembles of equally correlated graphs and apply this novel technique to the case of attractor neural networks. Assortativity turns out to be a key feature for memory performance in these systems - so much so that for sufficiently correlated topologies the critical temperature diverges. We predict that artificial and biological neural systems could significantly enhance their robustness to noise by developing positive correlations.

A visual analytics system for optimizing the performance of large-scale networks in supercomputing systems

Directory of Open Access Journals (Sweden)

Takanori Fujiwara

2018-03-01

Full Text Available The overall efficiency of an extreme-scale supercomputer largely relies on the performance of its network interconnects. Several of the state of the art supercomputers use networks based on the increasingly popular Dragonfly topology. It is crucial to study the behavior and performance of different parallel applications running on Dragonfly networks in order to make optimal system configurations and design choices, such as job scheduling and routing strategies. However, in order to study these temporal network behavior, we would need a tool to analyze and correlate numerous sets of multivariate time-series data collected from the Dragonfly’s multi-level hierarchies. This paper presents such a tool–a visual analytics system–that uses the Dragonfly network to investigate the temporal behavior and optimize the communication performance of a supercomputer. We coupled interactive visualization with time-series analysis methods to help reveal hidden patterns in the network behavior with respect to different parallel applications and system configurations. Our system also provides multiple coordinated views for connecting behaviors observed at different levels of the network hierarchies, which effectively helps visual analysis tasks. We demonstrate the effectiveness of the system with a set of case studies. Our system and findings can not only help improve the communication performance of supercomputing applications, but also the network performance of next-generation supercomputers. Keywords: Supercomputing, Parallel communication network, Dragonfly networks, Time-series data, Performance analysis, Visual analytics

Performance modeling, loss networks, and statistical multiplexing

CERN Document Server

Mazumdar, Ravi

2009-01-01

This monograph presents a concise mathematical approach for modeling and analyzing the performance of communication networks with the aim of understanding the phenomenon of statistical multiplexing. The novelty of the monograph is the fresh approach and insights provided by a sample-path methodology for queueing models that highlights the important ideas of Palm distributions associated with traffic models and their role in performance measures. Also presented are recent ideas of large buffer, and many sources asymptotics that play an important role in understanding statistical multiplexing. I

The Global Seismographic Network (GSN): Deployment of Next Generation VBB Borehole Sensors and Improving Overall Network Noise Performance

Science.gov (United States)

Hafner, K.; Davis, P.; Wilson, D.; Sumy, D.

2017-12-01

The Global Seismographic Network (GSN) recently received delivery of the next generation Very Broadband (VBB) borehole sensors purchased through funding from the DOE. Deployment of these sensors will be underway during the end of summer and fall of 2017 and they will eventually replace the aging KS54000 sensors at approximately one-third of the GSN network stations. We will present the latest methods of deploying these sensors in the existing deep boreholes. To achieve lower noise performance at some sites, emplacement in shallow boreholes might result in lower noise performance for the existing site conditions. In some cases shallow borehole installations may be adapted to vault stations (which make up two thirds of the network), as a means of reducing tilt-induced signals on the horizontal components. The GSN is creating a prioritized list of equipment upgrades at selected stations with the ultimate goal of optimizing overall network data availability and noise performance. For an overview of the performance of the current GSN relative to selected set of metrics, we are utilizing data quality metrics and Probability Density Functions (PDFs)) generated by the IRIS Data Management Centers' (DMC) MUSTANG (Modular Utility for Statistical Knowledge Gathering) and LASSO (Latest Assessment of Seismic Station Observations) tools. We will present our metric analysis of GSN performance in 2016, and show the improvements at GSN sites resulting from recent instrumentation and infrastructure upgrades.

Energetic Performance of Service-oriented Multi-radio Networks: Issues and Perspectives

OpenAIRE

Caporuscio , Mauro; Charlet , Damien; Issarny , Valérie; Navarra , Alfredo

2006-01-01

Wireless devices now hold multiple radio interfaces, allowing to switch from one network to another according to required connectivity and related quality. Still, the selection of the best radio interface for a specific connection is under the responsibility of the end-user in most cases. Integrated multi-radio network management so as to improve the overall performance of the network(s) has led to a number of research efforts over the last few years. However, several challenges remain due to...

Performance Analysis of RF-FSO Multi-Hop Networks

KAUST Repository

Makki, Behrooz; Svensson, Tommy; Brandt-Pearce, Maite; Alouini, Mohamed-Slim

2017-01-01

We study the performance of multi-hop networks composed of millimeter wave (MMW)-based radio frequency (RF) and free-space optical (FSO) links. The results are obtained in the cases with and without hybrid automatic repeat request (HARQ). Taking

Performance Analysis of Receive Diversity in Wireless Sensor Networks over GBSBE Models

Science.gov (United States)

Goel, Shivali; Abawajy, Jemal H.; Kim, Tai-hoon

2010-01-01

Wireless sensor networks have attracted a lot of attention recently. In this paper, we develop a channel model based on the elliptical model for multipath components involving randomly placed scatterers in the scattering region with sensors deployed on a field. We verify that in a sensor network, the use of receive diversity techniques improves the performance of the system. Extensive performance analysis of the system is carried out for both single and multiple antennas with the applied receive diversity techniques. Performance analyses based on variations in receiver height, maximum multipath delay and transmit power have been performed considering different numbers of antenna elements present in the receiver array, Our results show that increasing the number of antenna elements for a wireless sensor network does indeed improve the BER rates that can be obtained. PMID:22163510

Statistical performance evaluation of ECG transmission using wireless networks.

Science.gov (United States)

Shakhatreh, Walid; Gharaibeh, Khaled; Al-Zaben, Awad

2013-07-01

This paper presents simulation of the transmission of biomedical signals (using ECG signal as an example) over wireless networks. Investigation of the effect of channel impairments including SNR, pathloss exponent, path delay and network impairments such as packet loss probability; on the diagnosability of the received ECG signal are presented. The ECG signal is transmitted through a wireless network system composed of two communication protocols; an 802.15.4- ZigBee protocol and an 802.11b protocol. The performance of the transmission is evaluated using higher order statistics parameters such as kurtosis and Negative Entropy in addition to the common techniques such as the PRD, RMS and Cross Correlation.

Subjective Evaluation of Packet Service Performance in UMTS and Heterogeneous Networks

DEFF Research Database (Denmark)

Teyeb, Oumer Mohammed; Sørensen, Troels Bundgaard; Mogensen, Preben

2006-01-01

Quality of Service (QoS) in mobile telecommunication systems is usually identified by some basic performance metrics such as delay, throughput and jitter. However, the main impact of service quality is on the end user, and as such a detailed study of service performance should involve the end user......, users rated the perceived quality of the services under different network conditions. The users’ ratings are analyzed and the results showed clear trends with very few outliers. The objective and subjective measures also were found to be in line except for one case where a higher layer effect influenced....... In this paper, such an approach is taken where subjective performance evaluation is undertaken for web browsing and video streaming services in Universal Mobile Telecommunication System (UMTS) and a heterogeneous network comprised of UMTS and Wireless LAN (WLAN). Using a real-time network emulation testbed...

Performance and Complexity of Tunable Sparse Network Coding with Gradual Growing Tuning Functions over Wireless Networks

DEFF Research Database (Denmark)

Garrido, Pablo; Sørensen, Chres Wiant; Roetter, Daniel Enrique Lucani

2016-01-01

Random Linear Network Coding (RLNC) has been shown to be a technique with several benefits, in particular when applied over wireless mesh networks, since it provides robustness against packet losses. On the other hand, Tunable Sparse Network Coding (TSNC) is a promising concept, which leverages...... a trade-off between computational complexity and goodput. An optimal density tuning function has not been found yet, due to the lack of a closed-form expression that links density, performance and computational cost. In addition, it would be difficult to implement, due to the feedback delay. In this work...

Investigating And Evaluating Of Network Failures And Performance Over Distributed WAN In Application Protocol Layer

Directory of Open Access Journals (Sweden)

Enoch Okoh Kofi

2015-08-01

Full Text Available The Experiment was done to find out network failures and application performance relationship over distributed Wide Area Net WAN. In order to access related application over the cloud there must be an internet connectivity which will help the respective workstations to access the remote server for applications being deployed over the network. Bandwidth improvement helps in reducing utilization over the network and it also helps in improving Application Efficiency of these Applications in terms of Response Time. Routers were configured under Enhance Interior Gateway Routing Protocol EIGRP to reduce utilization and to ensure load sharing over the network. Three scenarios were modeled and their performance efficiency was evaluated. A modeled computer Network with and without a fail Router under different scenarios and such Network was simulated with emphasis on the Application Performance. The Experiment was done for fifty workstations under three scenarios and these three scenarios were accessed and evaluated on experimental basis using Riverbed modeler to show the Effect of Application Network performance. The performance results show that increasing the bandwidth reduces utilization and also with the failure of one communication bandwidth users can still access Network Application with a minimal cost.

OPTIMAL CONFIGURATION OF A COMMAND AND CONTROL NETWORK: BALANCING PERFORMANCE AND RECONFIGURATION CONSTRAINTS

Energy Technology Data Exchange (ETDEWEB)

L. DOWELL

1999-08-01

The optimization of the configuration of communications and control networks is important for assuring the reliability and performance of the networks. This paper presents techniques for determining the optimal configuration for such a network in the presence of communication and connectivity constraints. reconfiguration to restore connectivity to a data-fusion network following the failure of a network component.

Performance Analysis of Cluster Formation in Wireless Sensor Networks.

Science.gov (United States)

Montiel, Edgar Romo; Rivero-Angeles, Mario E; Rubino, Gerardo; Molina-Lozano, Heron; Menchaca-Mendez, Rolando; Menchaca-Mendez, Ricardo

2017-12-13

Clustered-based wireless sensor networks have been extensively used in the literature in order to achieve considerable energy consumption reductions. However, two aspects of such systems have been largely overlooked. Namely, the transmission probability used during the cluster formation phase and the way in which cluster heads are selected. Both of these issues have an important impact on the performance of the system. For the former, it is common to consider that sensor nodes in a clustered-based Wireless Sensor Network (WSN) use a fixed transmission probability to send control data in order to build the clusters. However, due to the highly variable conditions experienced by these networks, a fixed transmission probability may lead to extra energy consumption. In view of this, three different transmission probability strategies are studied: optimal, fixed and adaptive. In this context, we also investigate cluster head selection schemes, specifically, we consider two intelligent schemes based on the fuzzy C-means and k-medoids algorithms and a random selection with no intelligence. We show that the use of intelligent schemes greatly improves the performance of the system, but their use entails higher complexity and selection delay. The main performance metrics considered in this work are energy consumption, successful transmission probability and cluster formation latency. As an additional feature of this work, we study the effect of errors in the wireless channel and the impact on the performance of the system under the different transmission probability schemes.

Performance Analysis of Cluster Formation in Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Edgar Romo Montiel

2017-12-01

Full Text Available Clustered-based wireless sensor networks have been extensively used in the literature in order to achieve considerable energy consumption reductions. However, two aspects of such systems have been largely overlooked. Namely, the transmission probability used during the cluster formation phase and the way in which cluster heads are selected. Both of these issues have an important impact on the performance of the system. For the former, it is common to consider that sensor nodes in a clustered-based Wireless Sensor Network (WSN use a fixed transmission probability to send control data in order to build the clusters. However, due to the highly variable conditions experienced by these networks, a fixed transmission probability may lead to extra energy consumption. In view of this, three different transmission probability strategies are studied: optimal, fixed and adaptive. In this context, we also investigate cluster head selection schemes, specifically, we consider two intelligent schemes based on the fuzzy C-means and k-medoids algorithms and a random selection with no intelligence. We show that the use of intelligent schemes greatly improves the performance of the system, but their use entails higher complexity and selection delay. The main performance metrics considered in this work are energy consumption, successful transmission probability and cluster formation latency. As an additional feature of this work, we study the effect of errors in the wireless channel and the impact on the performance of the system under the different transmission probability schemes.

Value networks in manufacturing sustainability and performance excellence

CERN Document Server

Uusitalo, Teuvo

2017-01-01

This book highlights innovative solutions together with various techniques and methods that can help support the manufacturing sector to excel in economic, social, and environmental terms in networked business environments. The book also furthers understanding of sustainable manufacturing from the perspective of value creation in manufacturing networks, by capitalizing on the outcomes of the European ‘Sustainable Value Creation in Manufacturing Networks’ project. New dynamics and uncertainties in modern markets call for innovative solutions in the global manufacturing sector. While the manufacturing sector is traditionally driven by technology, it also requires other managerial and organizational solutions in terms of network governance, business models, sustainable solution development for products and services, performance management portals, etc., which can provide major competitive advantages for companies. At the same time, the manufacturing industry is subject to a change process, where business net...

Network Performance Evaluation of Abis Interface over DVB-S2 in the GSM over Satellite Network

Directory of Open Access Journals (Sweden)

S. B. Musabekov

2010-01-01

Full Text Available This paper deals with establishing a GSM link over Satellite. Abis interface, which is defined between Base Transceiver Station (BTS and Base Station Controller (BSC, in a GSM network is considered here to be routed over the Satellite. The satellite link enables a quick and cost-effective GSM link in meagerly populated areas. A different scenario comparison was done to understand the impact of Satellite environment on network availability comparing to terrestrial scenario. We have implemented an Abis interface over DVB S2 in NS2 and evaluated the performance over the high delay and loss satellite channel. Network performance was evaluated with respect to Satellite channel delay and DVB S2 encapsulation efficiency under different amount of user traffic and compared with the terrestrial scenario. The results clearly showed an increased amount of SDCCH and TCH channels required in the case of satellite scenario for the same amount of traffic in comparison to conventional terrestrial scenario. We have optimized the parameters based on the simulation results. Link budget estimation considering DVB-S2 platform was done to find satellite bandwidth and cost requirements for different network setups.

Performance Analysis of Receive Diversity in Wireless Sensor Networks over GBSBE Models

Directory of Open Access Journals (Sweden)

Tai-hoon Kim

2010-12-01

Full Text Available Wireless sensor networks have attracted a lot of attention recently. In this paper, we develop a channel model based on the elliptical model for multipath components involving randomly placed scatterers in the scattering region with sensors deployed on a field. We verify that in a sensor network, the use of receive diversity techniques improves the performance of the system. Extensive performance analysis of the system is carried out for both single and multiple antennas with the applied receive diversity techniques. Performance analyses based on variations in receiver height, maximum multipath delay and transmit power have been performed considering different numbers of antenna elements present in the receiver array, Our results show that increasing the number of antenna elements for a wireless sensor network does indeed improve the BER rates that can be obtained.

Factors Influencing the Performance of German Food SME Formal Networks

Directory of Open Access Journals (Sweden)

Jivka Deiters

2014-08-01

Full Text Available The food sector in Europe can be characterized as a complex, global and dynamically changing network of trade streams, food supply network relations and related product flows which offers a big spectrum for economic output and employment. Innovation is important for the competitiveness of the food industry that is to a large extent comprised of small and medium sized enterprises (SMEs. For them, innovation has grown extremely subordinate to interaction in networks. Network initiatives that could provide appropriate support involve social interaction and knowledge exchange, learning and competence development, and coordination (organization and management ofimplementation. This paper is designed to assess the factors that affect the performance of German food SME formal networks. It also addresses the consequences at the network and macro level. The analysis was explored by using the laddering technique based on the means‐end chain theory. The findings will help to build up a “network learning toolbox” that is adapted to the particular requirements of the different target groups such as of SMEs, network managers and policy makers. The “network learning toolbox” should improve network learning, which is adriver for improvements in innovation, economic growth and sustainable competitive advantage for food SMEs.

From Network to Research – Ten Years of Music Informatics, Performance and Aesthetics

DEFF Research Database (Denmark)

Frimodt-Møller, Søren R.; Grund, Cynthia M.; Jensen, Kristoffer

2011-01-01

This article briefly chronicles the history of the Nordic Network of Music Informatics, Performance and Aesthetics (NNIMIPA) and its roots in previous research networks and milieus. It explains how a cross-disciplinary network works and gives rise to research projects that bridge the gap between...... the disciplines involved. As examples, three thematically linked projects within NNIMIPA are presented. These projects all have performance interaction (between musicians and between musician and audience) as their nexus....

PERFORMANCE EVALUATION OF VARIANCES IN BACKPROPAGATION NEURAL NETWORK USED FOR HANDWRITTEN CHARACTER RECOGNITION

OpenAIRE

Vairaprakash Gurusamy *1 & K.Nandhini2

2017-01-01

A Neural Network is a powerful data modeling tool that is able to capture and represent complex input/output relationships. The motivation for the development of neural network technology stemmed from the desire to develop an artificial system that could perform "intelligent" tasks similar to those performed by the human brain.Back propagation was created by generalizing the Widrow-Hoff learning rule to multiple-layer networks and nonlinear differentiable transfer functions. The term back pro...

Externally induced frontoparietal synchronization modulates network dynamics and enhances working memory performance.

Science.gov (United States)

Violante, Ines R; Li, Lucia M; Carmichael, David W; Lorenz, Romy; Leech, Robert; Hampshire, Adam; Rothwell, John C; Sharp, David J

2017-03-14

Cognitive functions such as working memory (WM) are emergent properties of large-scale network interactions. Synchronisation of oscillatory activity might contribute to WM by enabling the coordination of long-range processes. However, causal evidence for the way oscillatory activity shapes network dynamics and behavior in humans is limited. Here we applied transcranial alternating current stimulation (tACS) to exogenously modulate oscillatory activity in a right frontoparietal network that supports WM. Externally induced synchronization improved performance when cognitive demands were high. Simultaneously collected fMRI data reveals tACS effects dependent on the relative phase of the stimulation and the internal cognitive processing state. Specifically, synchronous tACS during the verbal WM task increased parietal activity, which correlated with behavioral performance. Furthermore, functional connectivity results indicate that the relative phase of frontoparietal stimulation influences information flow within the WM network. Overall, our findings demonstrate a link between behavioral performance in a demanding WM task and large-scale brain synchronization.

IMPACT OF SOCIAL NETWORK STRUCTURE ON EMPLOYEE PERFORMANCE: A COMPARATIVE STUDY

OpenAIRE

Claudio Lira Meirelles; Thais Cereda Ravasi; Fabio Teixeira Arten; João Paulo Lara Siqueira

2013-01-01

This research sought to understand the relationship between the position of the central actor and the performance of a network, checking the influence of the central actor's performance over other actors. Among the specific objectives, we sought to describe the transactional content, the nature of the connections and the structural characteristics of the network. Data were collected through a questionnaire and analyzed with the help of software UCINET 6.0 and Excel. The results suggest tha...

A network application for modeling a centrifugal compressor performance map

Science.gov (United States)

Nikiforov, A.; Popova, D.; Soldatova, K.

2017-08-01

The approximation of aerodynamic performance of a centrifugal compressor stage and vaneless diffuser by neural networks is presented. Advantages, difficulties and specific features of the method are described. An example of a neural network and its structure is shown. The performances in terms of efficiency, pressure ratio and work coefficient of 39 model stages within the range of flow coefficient from 0.01 to 0.08 were modeled with mean squared error 1.5 %. In addition, the loss and friction coefficients of vaneless diffusers of relative widths 0.014-0.10 are modeled with mean squared error 2.45 %.

Ensemble of classifiers based network intrusion detection system performance bound

CSIR Research Space (South Africa)

Mkuzangwe, Nenekazi NP

2017-11-01

Full Text Available This paper provides a performance bound of a network intrusion detection system (NIDS) that uses an ensemble of classifiers. Currently researchers rely on implementing the ensemble of classifiers based NIDS before they can determine the performance...

Performance Analysis of TDMA Protocol in a Femtocell Network

Directory of Open Access Journals (Sweden)

Wanod Kumar

2014-07-01

Full Text Available In this paper, we evaluate the performance of TDMA (Time Division Multiple Access protocol using queuing theory in a femtocell network. The fair use of wireless channel among the users of network is carried out using TDMA protocol. The arrival of data packets from M communicating nodes becomes multiple Poisson process. The time slots of TDMA protocol represent c servers to communicate data packets coming from communicating nodes to the input of FAP (Femtocell Access Point. The service time of each server (time slot is exponentially distributed. This complete communication scenario using TDMA protocol is modeled using M/M/c queue. The performance of the protocol is evaluated in terms of mean number in system, average system delay and utilization for varying traffic intensity

Consensus group sessions are useful to reconcile stakeholders’ perspectives about network performance evaluation

Directory of Open Access Journals (Sweden)

Marie-Eve Lamontagne

2010-12-01

Full Text Available Background: Having a common vision among network stakeholders is an important ingredient to developing a performance evaluation process. Consensus methods may be a viable means to reconcile the perceptions of different stakeholders about the dimensions to include in a performance evaluation framework.Objectives: To determine whether individual organizations within traumatic brain injury (TBI networks differ in perceptions about the importance of performance dimensions for the evaluation of TBI networks and to explore the extent to which group consensus sessions could reconcile these perceptions.Methods: We used TRIAGE, a consensus technique that combines an individual and a group data collection phase to explore the perceptions of network stakeholders and to reach a consensus within structured group discussions.Results: One hundred and thirty-nine professionals from 43 organizations within eight TBI networks participated in the individual data collection; 62 professionals from these same organisations contributed to the group data collection. The extent of consensus based on questionnaire results (e.g. individual data collection was low, however, 100% agreement was obtained for each network during the consensus group sessions. The median importance scores and mean ranks attributed to the dimensions by individuals compared to groups did not differ greatly. Group discussions were found useful in understanding the reasons motivating the scoring, for resolving differences among participants, and for harmonizing their values.Conclusion: Group discussions, as part of a consensus technique, appear to be a useful process to reconcile diverging perceptions of network performance among stakeholders.

Performing particle image velocimetry using artificial neural networks: a proof-of-concept

Science.gov (United States)

Rabault, Jean; Kolaas, Jostein; Jensen, Atle

2017-12-01

Traditional programs based on feature engineering are underperforming on a steadily increasing number of tasks compared with artificial neural networks (ANNs), in particular for image analysis. Image analysis is widely used in fluid mechanics when performing particle image velocimetry (PIV) and particle tracking velocimetry (PTV), and therefore it is natural to test the ability of ANNs to perform such tasks. We report for the first time the use of convolutional neural networks (CNNs) and fully connected neural networks (FCNNs) for performing end-to-end PIV. Realistic synthetic images are used for training the networks and several synthetic test cases are used to assess the quality of each network’s predictions and compare them with state-of-the-art PIV software. In addition, we present tests on real-world data that prove ANNs can be used not only with synthetic images but also with more noisy, imperfect images obtained in a real experimental setup. While the ANNs we present have slightly higher root mean square error than state-of-the-art cross-correlation methods, they perform better near edges and allow for higher spatial resolution than such methods. In addition, it is likely that one could with further work develop ANNs which perform better that the proof-of-concept we offer.

Performance Modeling of Communication Networks with Markov Chains

CERN Document Server

Mo, Jeonghoon

2010-01-01

This book is an introduction to Markov chain modeling with applications to communication networks. It begins with a general introduction to performance modeling in Chapter 1 where we introduce different performance models. We then introduce basic ideas of Markov chain modeling: Markov property, discrete time Markov chain (DTMe and continuous time Markov chain (CTMe. We also discuss how to find the steady state distributions from these Markov chains and how they can be used to compute the system performance metric. The solution methodologies include a balance equation technique, limiting probab

Performance Analysis of Non-saturated IEEE 802.11 DCF Networks

Science.gov (United States)

Zhai, Linbo; Zhang, Xiaomin; Xie, Gang

This letter presents a model with queueing theory to analyze the performance of non-saturated IEEE 802.11 DCF networks. We use the closed queueing network model and derive an approximate representation of throughput which can reveal the relationship between the throughput and the total offered load under finite traffic load conditions. The accuracy of the model is verified by extensive simulations.

Changes in brain network efficiency and working memory performance in aging.

Science.gov (United States)

Stanley, Matthew L; Simpson, Sean L; Dagenbach, Dale; Lyday, Robert G; Burdette, Jonathan H; Laurienti, Paul J

2015-01-01

Working memory is a complex psychological construct referring to the temporary storage and active processing of information. We used functional connectivity brain network metrics quantifying local and global efficiency of information transfer for predicting individual variability in working memory performance on an n-back task in both young (n = 14) and older (n = 15) adults. Individual differences in both local and global efficiency during the working memory task were significant predictors of working memory performance in addition to age (and an interaction between age and global efficiency). Decreases in local efficiency during the working memory task were associated with better working memory performance in both age cohorts. In contrast, increases in global efficiency were associated with much better working performance for young participants; however, increases in global efficiency were associated with a slight decrease in working memory performance for older participants. Individual differences in local and global efficiency during resting-state sessions were not significant predictors of working memory performance. Significant group whole-brain functional network decreases in local efficiency also were observed during the working memory task compared to rest, whereas no significant differences were observed in network global efficiency. These results are discussed in relation to recently developed models of age-related differences in working memory.

Visualizing Network Traffic to Understand the Performance of Massively Parallel Simulations

KAUST Repository

Landge, A. G.

2012-12-01

The performance of massively parallel applications is often heavily impacted by the cost of communication among compute nodes. However, determining how to best use the network is a formidable task, made challenging by the ever increasing size and complexity of modern supercomputers. This paper applies visualization techniques to aid parallel application developers in understanding the network activity by enabling a detailed exploration of the flow of packets through the hardware interconnect. In order to visualize this large and complex data, we employ two linked views of the hardware network. The first is a 2D view, that represents the network structure as one of several simplified planar projections. This view is designed to allow a user to easily identify trends and patterns in the network traffic. The second is a 3D view that augments the 2D view by preserving the physical network topology and providing a context that is familiar to the application developers. Using the massively parallel multi-physics code pF3D as a case study, we demonstrate that our tool provides valuable insight that we use to explain and optimize pF3D-s performance on an IBM Blue Gene/P system. © 1995-2012 IEEE.

The company you keep: Effects of leader and teams network position on performance

NARCIS (Netherlands)

Vernet, A; Deichmann, D.; Moser, C.

2016-01-01

In this paper we argue that leaders positively influence team performance through their positions in a collaboration network. We propose also that the leader’s effect on team performance is moderated by the position of the team in the larger collaboration network. We distinguish between brokerage

A Public-Private Partnership Improves Clinical Performance In A Hospital Network In Lesotho.

Science.gov (United States)

McIntosh, Nathalie; Grabowski, Aria; Jack, Brian; Nkabane-Nkholongo, Elizabeth Limakatso; Vian, Taryn

2015-06-01

Health care public-private partnerships (PPPs) between a government and the private sector are based on a business model that aims to leverage private-sector expertise to improve clinical performance in hospitals and other health facilities. Although the financial implications of such partnerships have been analyzed, few studies have examined the partnerships' impact on clinical performance outcomes. Using quantitative measures that reflected capacity, utilization, clinical quality, and patient outcomes, we compared a government-managed hospital network in Lesotho, Africa, and the new PPP-managed hospital network that replaced it. In addition, we used key informant interviews to help explain differences in performance. We found that the PPP-managed network delivered more and higher-quality services and achieved significant gains in clinical outcomes, compared to the government-managed network. We conclude that health care public-private partnerships may improve hospital performance in developing countries and that changes in management and leadership practices might account for differences in clinical outcomes. Project HOPE—The People-to-People Health Foundation, Inc.

Ubiquitous Emergency Medical Service System Based on Wireless Biosensors, Traffic Information, and Wireless Communication Technologies: Development and Evaluation

Directory of Open Access Journals (Sweden)

Tan-Hsu Tan

2017-01-01

Full Text Available This study presents a new ubiquitous emergency medical service system (UEMS that consists of a ubiquitous tele-diagnosis interface and a traffic guiding subsystem. The UEMS addresses unresolved issues of emergency medical services by managing the sensor wires for eliminating inconvenience for both patients and paramedics in an ambulance, providing ubiquitous accessibility of patients’ biosignals in remote areas where the ambulance cannot arrive directly, and offering availability of real-time traffic information which can make the ambulance reach the destination within the shortest time. In the proposed system, patient’s biosignals and real-time video, acquired by wireless biosensors and a webcam, can be simultaneously transmitted to an emergency room for pre-hospital treatment via WiMax/3.5 G networks. Performances of WiMax and 3.5 G, in terms of initialization time, data rate, and average end-to-end delay are evaluated and compared. A driver can choose the route of the shortest time among the suggested routes by Google Maps after inspecting the current traffic conditions based on real-time CCTV camera streams and traffic information. The destination address can be inputted vocally for easiness and safety in driving. A series of field test results validates the feasibility of the proposed system for application in real-life scenarios.

Análisis de la calidad de servicio de las tecnologías CDMA 450 y Wimax para la comunicación en las parroquias rurales de los cantones Azogues, Cañar y Déleg brindado por la Corporación Nacional de Telecomunicaciones sucursal Cañar

OpenAIRE

Asitimbay Regalado, Mayra Yolanda; González Cabrera, Irene Priscila

2010-01-01

Este trabajo de tesis presenta el análisis de la calidad de servicio de telefonía brindado a través de la tecnología CDMA450, y del servicio de datos (Internet) prestados mediante la tecnología inalámbrica WiMAX por la Corporación Nacional de Telecomunicaciones (CNT) Sucursal Cañar, este análisis refleja la percepción que tienen los usuarios de estos servicios, así como de los datos obtenidos de sus equipos terminales.

Fuzzy Logic based Handoff Latency Reduction Mechanism in Layer 2 of Heterogeneous Mobile IPv6 Networks

Science.gov (United States)

Anwar, Farhat; Masud, Mosharrof H.; Latif, Suhaimi A.

2013-12-01

Mobile IPv6 (MIPv6) is one of the pioneer standards that support mobility in IPv6 environment. It has been designed to support different types of technologies for providing seamless communications in next generation network. However, MIPv6 and subsequent standards have some limitations due to its handoff latency. In this paper, a fuzzy logic based mechanism is proposed to reduce the handoff latency of MIPv6 for Layer 2 (L2) by scanning the Access Points (APs) while the Mobile Node (MN) is moving among different APs. Handoff latency occurs when the MN switches from one AP to another in L2. Heterogeneous network is considered in this research in order to reduce the delays in L2. Received Signal Strength Indicator (RSSI) and velocity of the MN are considered as the input of fuzzy logic technique. This technique helps the MN to measure optimum signal quality from APs for the speedy mobile node based on fuzzy logic input rules and makes a list of interfaces. A suitable interface from the list of available interfaces can be selected like WiFi, WiMAX or GSM. Simulation results show 55% handoff latency reduction and 50% packet loss improvement in L2 compared to standard to MIPv6.

Fuzzy Logic based Handoff Latency Reduction Mechanism in Layer 2 of Heterogeneous Mobile IPv6 Networks

International Nuclear Information System (INIS)

Anwar, Farhat; Masud, Mosharrof H; Latif, Suhaimi A

2013-01-01

Mobile IPv6 (MIPv6) is one of the pioneer standards that support mobility in IPv6 environment. It has been designed to support different types of technologies for providing seamless communications in next generation network. However, MIPv6 and subsequent standards have some limitations due to its handoff latency. In this paper, a fuzzy logic based mechanism is proposed to reduce the handoff latency of MIPv6 for Layer 2 (L2) by scanning the Access Points (APs) while the Mobile Node (MN) is moving among different APs. Handoff latency occurs when the MN switches from one AP to another in L2. Heterogeneous network is considered in this research in order to reduce the delays in L2. Received Signal Strength Indicator (RSSI) and velocity of the MN are considered as the input of fuzzy logic technique. This technique helps the MN to measure optimum signal quality from APs for the speedy mobile node based on fuzzy logic input rules and makes a list of interfaces. A suitable interface from the list of available interfaces can be selected like WiFi, WiMAX or GSM. Simulation results show 55% handoff latency reduction and 50% packet loss improvement in L2 compared to standard to MIPv6

A Hybrid Testbed for Performance Evaluation of Large-Scale Datacenter Networks

DEFF Research Database (Denmark)

Pilimon, Artur; Ruepp, Sarah Renée

2018-01-01

Datacenters (DC) as well as their network interconnects are growing in scale and complexity. They are constantly being challenged in terms of energy and resource utilization efficiency, scalability, availability, reliability and performance requirements. Therefore, these resource-intensive enviro......Datacenters (DC) as well as their network interconnects are growing in scale and complexity. They are constantly being challenged in terms of energy and resource utilization efficiency, scalability, availability, reliability and performance requirements. Therefore, these resource......-intensive environments must be properly tested and analyzed in order to make timely upgrades and transformations. However, a limited number of academic institutions and Research and Development companies have access to production scale DC Network (DCN) testing facilities, and resource-limited studies can produce...... misleading or inaccurate results. To address this problem, we introduce an alternative solution, which forms a solid base for a more realistic and comprehensive performance evaluation of different aspects of DCNs. It is based on the System-in-the-loop (SITL) concept, where real commercial DCN equipment...

High-performance, scalable optical network-on-chip architectures

Science.gov (United States)

Tan, Xianfang

The rapid advance of technology enables a large number of processing cores to be integrated into a single chip which is called a Chip Multiprocessor (CMP) or a Multiprocessor System-on-Chip (MPSoC) design. The on-chip interconnection network, which is the communication infrastructure for these processing cores, plays a central role in a many-core system. With the continuously increasing complexity of many-core systems, traditional metallic wired electronic networks-on-chip (NoC) became a bottleneck because of the unbearable latency in data transmission and extremely high energy consumption on chip. Optical networks-on-chip (ONoC) has been proposed as a promising alternative paradigm for electronic NoC with the benefits of optical signaling communication such as extremely high bandwidth, negligible latency, and low power consumption. This dissertation focus on the design of high-performance and scalable ONoC architectures and the contributions are highlighted as follow: 1. A micro-ring resonator (MRR)-based Generic Wavelength-routed Optical Router (GWOR) is proposed. A method for developing any sized GWOR is introduced. GWOR is a scalable non-blocking ONoC architecture with simple structure, low cost and high power efficiency compared to existing ONoC designs. 2. To expand the bandwidth and improve the fault tolerance of the GWOR, a redundant GWOR architecture is designed by cascading different type of GWORs into one network. 3. The redundant GWOR built with MRR-based comb switches is proposed. Comb switches can expand the bandwidth while keep the topology of GWOR unchanged by replacing the general MRRs with comb switches. 4. A butterfly fat tree (BFT)-based hybrid optoelectronic NoC (HONoC) architecture is developed in which GWORs are used for global communication and electronic routers are used for local communication. The proposed HONoC uses less numbers of electronic routers and links than its counterpart of electronic BFT-based NoC. It takes the advantages of

Throughput performance analysis of multirate, multiclass S-ALOHA OFFH-CDMA packet networks

DEFF Research Database (Denmark)

Raddo, Thiago R.; Sanches, Anderson L.; Borges, Ben Hur V

2015-01-01

In this paper, we propose a new throughput expression for multirate, multiclass slotted-ALOHA optical fast frequency hopping code-division multiple-access (OFFH-CDMA) packet networks considering a Poisson distribution for packet composite arrivals. We analyze the packet throughput performance...... of a three-class OFFH-CDMA network, where multirate transmissions are achieved via manipulation of the user's code parameters. It is shown that users transmitting at low rates interfere considerably in the performance of high rate users. Finally, we perform a validation procedure to demonstrate...

Network survivability performance (computer diskette)

Science.gov (United States)

1993-11-01

File characteristics: Data file; 1 file. Physical description: 1 computer diskette; 3 1/2 in.; high density; 2.0MB. System requirements: Mac; Word. This technical report has been developed to address the survivability of telecommunications networks including services. It responds to the need for a common understanding of, and assessment techniques for network survivability, availability, integrity, and reliability. It provides a basis for designing and operating telecommunication networks to user expectations for network survivability.

OPTIMAL CONFIGURATION OF A COMMAND AND CONTROL NETWORK: BALANCING PERFORMANCE AND RECONFIGURATION CONSTRAINTS

Energy Technology Data Exchange (ETDEWEB)

L. DOWELL

1999-07-01

The optimization of the configuration of communications and control networks is important for assuring the reliability and performance of the networks. This paper presents techniques for determining the optimal configuration for such a network in the presence of communication and connectivity constraints.

The Impact of Social Networks on Students’ Performance

OpenAIRE

Jusuf Zekiri

2016-01-01

The objective of this study is to determine the impact of using social media and its impact on students’ performance and success. This research tries to identify the relationship between students’ use of social networks and their success in their studies. It tries also to find out whether time spent impacts students’ performance and success. Whether students use social media more for entertainment or for teaching and information sharing purposes. The paper uses a quantitative approach for col...

An Efficient Scheme for Aggregation and Presentation of Network Performance in Distributed Brokering Systems

Directory of Open Access Journals (Sweden)

Gurhan Gunduz

2003-12-01

Full Text Available The Internet is presently being used to support increasingly complex interaction models as a result of more and more applications, services and frameworks becoming network centric. Efficient utilization of network and networkedresources is of paramount importance. Network performance gathering is a precursor to any scheme that seeks to provide adaptive routing capabilities for interactions. In this paper we present a network performance aggregation framework that is extensible and appropriate for distributed messaging systems that span multiple realms, disparate communication protocols and support different applications.

HPNAIDM: The High-Performance Network Anomaly/Intrusion Detection and Mitigation System

Energy Technology Data Exchange (ETDEWEB)

Chen, Yan [Northwesten University

2013-12-05

Identifying traffic anomalies and attacks rapidly and accurately is critical for large network operators. With the rapid growth of network bandwidth, such as the next generation DOE UltraScience Network, and fast emergence of new attacks/virus/worms, existing network intrusion detection systems (IDS) are insufficient because they: • Are mostly host-based and not scalable to high-performance networks; • Are mostly signature-based and unable to adaptively recognize flow-level unknown attacks; • Cannot differentiate malicious events from the unintentional anomalies. To address these challenges, we proposed and developed a new paradigm called high-performance network anomaly/intrustion detection and mitigation (HPNAIDM) system. The new paradigm is significantly different from existing IDSes with the following features (research thrusts). • Online traffic recording and analysis on high-speed networks; • Online adaptive flow-level anomaly/intrusion detection and mitigation; • Integrated approach for false positive reduction. Our research prototype and evaluation demonstrate that the HPNAIDM system is highly effective and economically feasible. Beyond satisfying the pre-set goals, we even exceed that significantly (see more details in the next section). Overall, our project harvested 23 publications (2 book chapters, 6 journal papers and 15 peer-reviewed conference/workshop papers). Besides, we built a website for technique dissemination, which hosts two system prototype release to the research community. We also filed a patent application and developed strong international and domestic collaborations which span both academia and industry.

Study on multiple-hops performance of MOOC sequences-based optical labels for OPS networks

Science.gov (United States)

Zhang, Chongfu; Qiu, Kun; Ma, Chunli

2009-11-01

In this paper, we utilize a new study method that is under independent case of multiple optical orthogonal codes to derive the probability function of MOOCS-OPS networks, discuss the performance characteristics for a variety of parameters, and compare some characteristics of the system employed by single optical orthogonal code or multiple optical orthogonal codes sequences-based optical labels. The performance of the system is also calculated, and our results verify that the method is effective. Additionally it is found that performance of MOOCS-OPS networks would, negatively, be worsened, compared with single optical orthogonal code-based optical label for optical packet switching (SOOC-OPS); however, MOOCS-OPS networks can greatly enlarge the scalability of optical packet switching networks.

The Enhancing Impact of Friendship Networks on Sales Managers’ Performance

Directory of Open Access Journals (Sweden)

Danny Pimentel Claro

2013-04-01

Full Text Available This paper examines how relationships with friends moderate the impact of professional networks on sales performance. Based on a sample of 204 sales managers in a professional service company, this study presents evidence that friendship networks amplify the effect of sales forces’ professional networks on new product sales as well as on prospecting and converting new deals. Our results offer important insights into the socio-cognitive perspective of sales management literature and suggest that firms should encourage managers to improve their friendships in order to access valuable information that will enhance customer knowledge and support their sales efforts.

172 Networks, Micro Small Enterprises (MSE'S) and Performance ...

African Journals Online (AJOL)

User

It is no doubt that the role of entrepreneurship in the emerging economies such like Kenya ... understand networking and small business performance as there is no single general ... solution for small firm development (Borg 1991, Donckels and Lambrecht. 1995 ..... Scandinavian Journal of Management , 31 (3/4), 83-99.

Distributed dynamic simulations of networked control and building performance applications.

Science.gov (United States)

Yahiaoui, Azzedine

2018-02-01

The use of computer-based automation and control systems for smart sustainable buildings, often so-called Automated Buildings (ABs), has become an effective way to automatically control, optimize, and supervise a wide range of building performance applications over a network while achieving the minimum energy consumption possible, and in doing so generally refers to Building Automation and Control Systems (BACS) architecture. Instead of costly and time-consuming experiments, this paper focuses on using distributed dynamic simulations to analyze the real-time performance of network-based building control systems in ABs and improve the functions of the BACS technology. The paper also presents the development and design of a distributed dynamic simulation environment with the capability of representing the BACS architecture in simulation by run-time coupling two or more different software tools over a network. The application and capability of this new dynamic simulation environment are demonstrated by an experimental design in this paper.

From Network to Research – Ten Years of Music Informatics, Performance and Aesthetics

DEFF Research Database (Denmark)

Frimodt-Møller, Søren; Grund, Cynthia M.; Jensen, Kristoffer

2011-01-01

This article briefly chronicles the history of the Nordic Network of Music Informatics, Performance and Aesthetics (NNIMIPA) and its roots in previous research networks and milieus. It explains how a cross-disciplinary network works and gives rise to research projects that bridge the gap between...

Advanced Communication Technology Satellite (ACTS) Very Small Aperture Terminal (VSAT) Network Control Performance

Science.gov (United States)

Coney, T. A.

1996-01-01

This paper discusses the performance of the network control function for the Advanced Communications Technology Satellite (ACTS) very small aperture terminal (VSAT) full mesh network. This includes control of all operational activities such as acquisition, synchronization, timing and rain fade compensation as well as control of all communications activities such as on-demand integrated services (voice, video, and date) connects and disconnects Operations control is provided by an in-band orderwire carried in the baseboard processor (BBP) control burst, the orderwire burst, the reference burst, and the uplink traffic burst. Communication services are provided by demand assigned multiple access (DAMA) protocols. The ACTS implementation of DAMA protocols ensures both on-demand and integrated voice, video and data services. Communications services control is also provided by the in-band orderwire but uses only the reference burst and the uplink traffic burst. The performance of the ACTS network control functions have been successfully tested during on-orbit checkout and in various VSAT networks in day to day operations. This paper discusses the network operations and services control performance.

Evaluation of the Performance of Feedforward and Recurrent Neural Networks in Active Cancellation of Sound Noise

Directory of Open Access Journals (Sweden)

Mehrshad Salmasi

2012-07-01

Full Text Available Active noise control is based on the destructive interference between the primary noise and generated noise from the secondary source. An antinoise of equal amplitude and opposite phase is generated and combined with the primary noise. In this paper, performance of the neural networks is evaluated in active cancellation of sound noise. For this reason, feedforward and recurrent neural networks are designed and trained. After training, performance of the feedforwrad and recurrent networks in noise attenuation are compared. We use Elman network as a recurrent neural network. For simulations, noise signals from a SPIB database are used. In order to compare the networks appropriately, equal number of layers and neurons are considered for the networks. Moreover, training and test samples are similar. Simulation results show that feedforward and recurrent neural networks present good performance in noise cancellation. As it is seen, the ability of recurrent neural network in noise attenuation is better than feedforward network.

Energy efficient mechanisms for high-performance Wireless Sensor Networks

Science.gov (United States)

Alsaify, Baha'adnan

2009-12-01

Due to recent advances in microelectronics, the development of low cost, small, and energy efficient devices became possible. Those advances led to the birth of the Wireless Sensor Networks (WSNs). WSNs consist of a large set of sensor nodes equipped with communication capabilities, scattered in the area to monitor. Researchers focus on several aspects of WSNs. Such aspects include the quality of service the WSNs provide (data delivery delay, accuracy of data, etc...), the scalability of the network to contain thousands of sensor nodes (the terms node and sensor node are being used interchangeably), the robustness of the network (allowing the network to work even if a certain percentage of nodes fails), and making the energy consumption in the network as low as possible to prolong the network's lifetime. In this thesis, we present an approach that can be applied to the sensing devices that are scattered in an area for Sensor Networks. This work will use the well-known approach of using a awaking scheduling to extend the network's lifespan. We designed a scheduling algorithm that will reduce the delay's upper bound the reported data will experience, while at the same time keeps the advantages that are offered by the use of the awaking scheduling -- the energy consumption reduction which will lead to the increase in the network's lifetime. The wakeup scheduling is based on the location of the node relative to its neighbors and its distance from the Base Station (the terms Base Station and sink are being used interchangeably). We apply the proposed method to a set of simulated nodes using the "ONE Simulator". We test the performance of this approach with three other approaches -- Direct Routing technique, the well known LEACH algorithm, and a multi-parent scheduling algorithm. We demonstrate a good improvement on the network's quality of service and a reduction of the consumed energy.

Performance Study of Earth Networks Total Lightning Network using Rocket-Triggered Lightning Data in 2014

Science.gov (United States)

Heckman, S.

2015-12-01

Modern lightning locating systems (LLS) provide real-time monitoring and early warning of lightningactivities. In addition, LLS provide valuable data for statistical analysis in lightning research. It isimportant to know the performance of such LLS. In the present study, the performance of the EarthNetworks Total Lightning Network (ENTLN) is studied using rocket-triggered lightning data acquired atthe International Center for Lightning Research and Testing (ICLRT), Camp Blanding, Florida.In the present study, 18 flashes triggered at ICLRT in 2014 were analyzed and they comprise of 78negative cloud-to-ground return strokes. The geometric mean, median, minimum, and maximum for thepeak currents of the 78 return strokes are 13.4 kA, 13.6 kA, 3.7 kA, and 38.4 kA, respectively. The peakcurrents represent typical subsequent return strokes in natural cloud-to-ground lightning.Earth Networks has developed a new data processor to improve the performance of their network. Inthis study, results are presented for the ENTLN data using the old processor (originally reported in 2014)and the ENTLN data simulated using the new processor. The flash detection efficiency, stroke detectionefficiency, percentage of misclassification, median location error, median peak current estimation error,and median absolute peak current estimation error for the originally reported data from old processorare 100%, 94%, 49%, 271 m, 5%, and 13%, respectively, and those for the simulated data using the newprocessor are 100%, 99%, 9%, 280 m, 11%, and 15%, respectively. The use of new processor resulted inhigher stroke detection efficiency and lower percentage of misclassification. It is worth noting that theslight differences in median location error, median peak current estimation error, and median absolutepeak current estimation error for the two processors are due to the fact that the new processordetected more number of return strokes than the old processor.

Performance analysis of multi-hop wireless packet networks

Directory of Open Access Journals (Sweden)

Lim J.-T.

1997-01-01

Full Text Available In this paper, a unified analytical framework for performance analysis of multi-hop wireless packet networks is developed. The effect of coupling between the hops on the degradation of the delay-throughput characteristics and the probability of blocking is investigated. The issue of hop decoupling is addressed.

Long-running telemedicine networks delivering humanitarian services: experience, performance and scientific output

Science.gov (United States)

Geissbuhler, Antoine; Jethwani, Kamal; Kovarik, Carrie; Person, Donald A; Vladzymyrskyy, Anton; Zanaboni, Paolo; Zolfo, Maria

2012-01-01

Abstract Objective To summarize the experience, performance and scientific output of long-running telemedicine networks delivering humanitarian services. Methods Nine long-running networks – those operating for five years or more– were identified and seven provided detailed information about their activities, including performance and scientific output. Information was extracted from peer-reviewed papers describing the networks’ study design, effectiveness, quality, economics, provision of access to care and sustainability. The strength of the evidence was scored as none, poor, average or good. Findings The seven networks had been operating for a median of 11 years (range: 5–15). All networks provided clinical tele-consultations for humanitarian purposes using store-and-forward methods and five were also involved in some form of education. The smallest network had 15 experts and the largest had more than 500. The clinical caseload was 50 to 500 cases a year. A total of 59 papers had been published by the networks, and 44 were listed in Medline. Based on study design, the strength of the evidence was generally poor by conventional standards (e.g. 29 papers described non-controlled clinical series). Over half of the papers provided evidence of sustainability and improved access to care. Uncertain funding was a common risk factor. Conclusion Improved collaboration between networks could help attenuate the lack of resources reported by some networks and improve sustainability. Although the evidence base is weak, the networks appear to offer sustainable and clinically useful services. These findings may interest decision-makers in developing countries considering starting, supporting or joining similar telemedicine networks. PMID:22589567

Centralized Routing and Scheduling Using Multi-Channel System Single Transceiver in 802.16d

Science.gov (United States)

Al-Hemyari, A.; Noordin, N. K.; Ng, Chee Kyun; Ismail, A.; Khatun, S.

This paper proposes a cross-layer optimized strategy that reduces the effect of interferences from neighboring nodes within a mesh networks. This cross-layer design relies on the routing information in network layer and the scheduling table in medium access control (MAC) layer. A proposed routing algorithm in network layer is exploited to find the best route for all subscriber stations (SS). Also, a proposed centralized scheduling algorithm in MAC layer is exploited to assign a time slot for each possible node transmission. The cross-layer optimized strategy is using multi-channel single transceiver and single channel single transceiver systems for WiMAX mesh networks (WMNs). Each node in WMN has a transceiver that can be tuned to any available channel for eliminating the secondary interference. Among the considered parameters in the performance analysis are interference from the neighboring nodes, hop count to the base station (BS), number of children per node, slot reuse, load balancing, quality of services (QoS), and node identifier (ID). Results show that the proposed algorithms significantly improve the system performance in terms of length of scheduling, channel utilization ratio (CUR), system throughput, and average end to end transmission delay.

A comparison of back propagation and generalized regression neural networks performance in neutron spectrometry

International Nuclear Information System (INIS)

Ortiz R, J. M.; Martinez B, M. R.; Solis S, L. O.; Castaneda M, R.; Vega C, H. R.

2015-10-01

The process of unfolding the neutron energy spectrum has been the subject of research for many years. Monte Carlo, iterative methods, the bayesian theory, the principle of maximum entropy are some of the methods used. The drawbacks associated with traditional unfolding procedures have motivated the need of complementary approaches. Back Propagation Neural Networks (BPNN), have been applied with success in the neutron spectrometry and dosimetry domains, however, the structure and the learning parameters are factors that contribute in a significant way in the networks performance. In artificial neural network domain, Generalized Regression Neural Network (GRNN) is one of the simplest neural networks in term of network architecture and learning algorithm. The learning is instantaneous, which mean require no time for training. Opposite to BPNN, a GRNN would be formed instantly with just a 1-pass training with the development data. In the network development phase, the only hurdle is to tune the hyper parameter, which is known as sigma, governing the smoothness of the network. The aim of this work was to compare the performance of BPNN and GRNN in the solution of the neutron spectrometry problem. From results obtained can be observed that despite the very similar results, GRNN performs better than BPNN. (Author)

A comparison of back propagation and generalized regression neural networks performance in neutron spectrometry

Energy Technology Data Exchange (ETDEWEB)

Ortiz R, J. M.; Martinez B, M. R.; Solis S, L. O.; Castaneda M, R. [Universidad Autonoma de Zacatecas, Unidad Academica de Ingenieria Electrica, Av. Ramon Lopez Velarde 801, Col. Centro, 98000 Zacatecas, Zac. (Mexico); Vega C, H. R., E-mail: morvymm@yahoo.com.mx [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico)

2015-10-15

The process of unfolding the neutron energy spectrum has been the subject of research for many years. Monte Carlo, iterative methods, the bayesian theory, the principle of maximum entropy are some of the methods used. The drawbacks associated with traditional unfolding procedures have motivated the need of complementary approaches. Back Propagation Neural Networks (BPNN), have been applied with success in the neutron spectrometry and dosimetry domains, however, the structure and the learning parameters are factors that contribute in a significant way in the networks performance. In artificial neural network domain, Generalized Regression Neural Network (GRNN) is one of the simplest neural networks in term of network architecture and learning algorithm. The learning is instantaneous, which mean require no time for training. Opposite to BPNN, a GRNN would be formed instantly with just a 1-pass training with the development data. In the network development phase, the only hurdle is to tune the hyper parameter, which is known as sigma, governing the smoothness of the network. The aim of this work was to compare the performance of BPNN and GRNN in the solution of the neutron spectrometry problem. From results obtained can be observed that despite the very similar results, GRNN performs better than BPNN. (Author)

On the TDD Subframe Structure for Beyond 4G Radio Access Network

DEFF Research Database (Denmark)

Lähetkangas, Eeva; Pajukoski, Kari; Tiirola, Esa

2013-01-01

The purpose of a Beyond 4G (B4G) radio access technology, is to cope with the expected exponential increase of mobile data traffic in local area (LA). The requirements related to physical layer control signaling latencies and to hybrid ARQ (HARQ) round trip time (RTT) are in the order of ~1ms...... requirement and significant control signaling latency reductions compared to existing LTE-Advanced and WiMAX technologies....

Performance evaluation of a burst-mode EDFA in an optical packet and circuit integrated network.

Science.gov (United States)

Shiraiwa, Masaki; Awaji, Yoshinari; Furukawa, Hideaki; Shinada, Satoshi; Puttnam, Benjamin J; Wada, Naoya

2013-12-30

We experimentally investigate the performance of burst-mode EDFA in an optical packet and circuit integrated system. In such networks, packets and light paths can be dynamically assigned to the same fibers, resulting in gain transients in EDFAs throughout the network that can limit network performance. Here, we compare the performance of a 'burst-mode' EDFA (BM-EDFA), employing transient suppression techniques and optical feedback, with conventional EDFAs, and those using automatic gain control and previous BM-EDFA implementations. We first measure gain transients and other impairments in a simplified set-up before making frame error-rate measurements in a network demonstration.

A comparison of back propagation and Generalized Regression Neural Networks performance in neutron spectrometry

International Nuclear Information System (INIS)

Martínez-Blanco, Ma. del Rosario

2016-01-01

The process of unfolding the neutron energy spectrum has been subject of research for many years. Monte Carlo, iterative methods, the bayesian theory, the principle of maximum entropy are some of the methods used. The drawbacks associated with traditional unfolding procedures have motivated the research of complementary approaches. Back Propagation Neural Networks (BPNN), have been applied with success in neutron spectrometry and dosimetry domains, however, the structure and learning parameters are factors that highly impact in the networks performance. In ANN domain, Generalized Regression Neural Network (GRNN) is one of the simplest neural networks in term of network architecture and learning algorithm. The learning is instantaneous, requiring no time for training. Opposite to BPNN, a GRNN would be formed instantly with just a 1-pass training on the development data. In the network development phase, the only hurdle is to optimize the hyper-parameter, which is known as sigma, governing the smoothness of the network. The aim of this work was to compare the performance of BPNN and GRNN in the solution of the neutron spectrometry problem. From results obtained it can be observed that despite the very similar results, GRNN performs better than BPNN.

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.

Design and implementation of a high performance network security processor

Science.gov (United States)

Wang, Haixin; Bai, Guoqiang; Chen, Hongyi

2010-03-01

The last few years have seen many significant progresses in the field of application-specific processors. One example is network security processors (NSPs) that perform various cryptographic operations specified by network security protocols and help to offload the computation intensive burdens from network processors (NPs). This article presents a high performance NSP system architecture implementation intended for both internet protocol security (IPSec) and secure socket layer (SSL) protocol acceleration, which are widely employed in virtual private network (VPN) and e-commerce applications. The efficient dual one-way pipelined data transfer skeleton and optimised integration scheme of the heterogenous parallel crypto engine arrays lead to a Gbps rate NSP, which is programmable with domain specific descriptor-based instructions. The descriptor-based control flow fragments large data packets and distributes them to the crypto engine arrays, which fully utilises the parallel computation resources and improves the overall system data throughput. A prototyping platform for this NSP design is implemented with a Xilinx XC3S5000 based FPGA chip set. Results show that the design gives a peak throughput for the IPSec ESP tunnel mode of 2.85 Gbps with over 2100 full SSL handshakes per second at a clock rate of 95 MHz.

Performance Analysis of Mobile Ad Hoc Unmanned Aerial Vehicle Communication Networks with Directional Antennas

Directory of Open Access Journals (Sweden)

Abdel Ilah Alshbatat

2010-01-01

Full Text Available Unmanned aerial vehicles (UAVs have the potential of creating an ad hoc communication network in the air. Most UAVs used in communication networks are equipped with wireless transceivers using omnidirectional antennas. In this paper, we consider a collection of UAVs that communicate through wireless links as a mobile ad-hoc network using directional antennas. The network design goal is to maximize the throughput and minimize the end-to-end delay. In this respect, we propose a new medium access control protocol for a network of UAVs with directional antennas. We analyze the communication channel between the UAVs and the effect of aircraft attitude on the network performance. Using the optimized network engineering tool (OPNET, we compare our protocol with the IEEE 802.11 protocol for omnidirectional antennas. The simulation results show performance improvement in end-to-end delay as well as throughput.

A Performance Analytical Strategy for Network-on-Chip Router with Input Buffer Architecture

Directory of Open Access Journals (Sweden)

WANG, J.

2012-11-01

Full Text Available In this paper, a performance analytical strategy is proposed for Network-on-Chip router with input buffer architecture. First, an analytical model is developed based on semi-Markov process. For the non-work-conserving router with small buffer size, the model can be used to analyze the schedule delay and the average service time for each buffer when given the related parameters. Then, the packet average delay in router is calculated by using the model. Finally, we validate the effectiveness of our strategy by simulation. By comparing our analytical results to simulation results, we show that our strategy successfully captures the Network-on-Chip router performance and it performs better than the state-of-art technology. Therefore, our strategy can be used as an efficiency performance analytical tool for Network-on-Chip design.

Delay performance of a broadcast spectrum sharing network in Nakagami-m fading

KAUST Repository

Khan, Fahd Ahmed; Tourki, Kamel; Alouini, Mohamed-Slim; Qaraqe, Khalid A.

2014-01-01

In this paper, we analyze the delay performance of a point-to-multipoint secondary network (P2M-SN), which is concurrently sharing the spectrum with a point-to-multipoint primary network (P2M-PN). The channel is assumed to be independent

Performance Analysis of Receive Diversity in Wireless Sensor Networks over GBSBE Models

OpenAIRE

Goel, Shivali; Abawajy, Jemal H.; Kim, Tai-hoon

2010-01-01

Wireless sensor networks have attracted a lot of attention recently. In this paper, we develop a channel model based on the elliptical model for multipath components involving randomly placed scatterers in the scattering region with sensors deployed on a field. We verify that in a sensor network, the use of receive diversity techniques improves the performance of the system. Extensive performance analysis of the system is carried out for both single and multiple antennas with the applied rece...

Classification of non-performing loans portfolio using Multilayer Perceptron artificial neural networks

Directory of Open Access Journals (Sweden)

Flávio Clésio Silva de Souza

2014-06-01

Full Text Available The purpose of the present research is to apply a Multilayer Perceptron (MLP neural network technique to create classification models from a portfolio of Non-Performing Loans (NPLs to classify this type of credit derivative. These credit derivatives are characterized as the amount of loans that were not paid and are already overdue more than 90 days. Since these titles are, because of legislative motives, moved by losses, Credit Rights Investment Funds (FDIC performs the purchase of these debts and the recovery of the credits. Using the Multilayer Perceptron (MLP architecture of Artificial Neural Network (ANN, classification models regarding the posterior recovery of these debts were created. To evaluate the performance of the models, evaluation metrics of classification relating to the neural networks with different architectures were presented. The results of the classifications were satisfactory, given the classification models were successful in the presented economics costs structure.

Performance of an opportunistic multi-user cognitive network with multiple primary users

KAUST Repository

Khan, Fahd Ahmed

2014-04-01

Consider a multi-user underlay cognitive network where multiple cognitive users, having limited peak transmit power, concurrently share the spectrum with a primary network with multiple users. The channel between the secondary network is assumed to have independent but not identical Nakagami-m fading. The interference channel between the secondary users and the primary users is assumed to have Rayleigh fading. The uplink scenario is considered where a single secondary user is selected for transmission. This opportunistic selection depends on the transmission channel power gain and the interference channel power gain as well as the power allocation policy adopted at the users. Exact closed form expressions for the momentgenerating function, outage performance and the symbol-error-rate performance are derived. The outage performance is also studied in the asymptotic regimes and the generalized diversity gain of this scheduling scheme is derived. Numerical results corroborate the derived analytical results.

Analyzing the Social Networks of High- and Low-Performing Students in Online Discussion Forums

Science.gov (United States)

Ghadirian, Hajar; Salehi, Keyvan; Ayub, Ahmad Fauzi Mohd

2018-01-01

An ego network is an individual's social network relationships with core members. In this study, the ego network parameters in online discussion spaces of high- and low-performing students were compared. The extent to which students' ego networks changed over the course were also analyzed. Participation in 7 weeks of online discussions were…

Error performance analysis in downlink cellular networks with interference management

KAUST Repository

Afify, Laila H.

2015-05-01

Modeling aggregate network interference in cellular networks has recently gained immense attention both in academia and industry. While stochastic geometry based models have succeeded to account for the cellular network geometry, they mostly abstract many important wireless communication system aspects (e.g., modulation techniques, signal recovery techniques). Recently, a novel stochastic geometry model, based on the Equivalent-in-Distribution (EiD) approach, succeeded to capture the aforementioned communication system aspects and extend the analysis to averaged error performance, however, on the expense of increasing the modeling complexity. Inspired by the EiD approach, the analysis developed in [1] takes into consideration the key system parameters, while providing a simple tractable analysis. In this paper, we extend this framework to study the effect of different interference management techniques in downlink cellular network. The accuracy of the proposed analysis is verified via Monte Carlo simulations.

Loss Performance Modeling for Hierarchical Heterogeneous Wireless Networks With Speed-Sensitive Call Admission Control

DEFF Research Database (Denmark)

Huang, Qian; Huang, Yue-Cai; Ko, King-Tim

2011-01-01

. This approach avoids unnecessary and frequent handoff between cells and reduces signaling overheads. An approximation model with guaranteed accuracy and low computational complexity is presented for the loss performance of multiservice traffic. The accuracy of numerical results is validated by comparing......A hierarchical overlay structure is an alternative solution that integrates existing and future heterogeneous wireless networks to provide subscribers with better mobile broadband services. Traffic loss performance in such integrated heterogeneous networks is necessary for an operator's network...

High Precision Testbed to Evaluate Ethernet Performance for In-Car Networks

DEFF Research Database (Denmark)

Revsbech, Kasper; Madsen, Tatiana Kozlova; Schiøler, Henrik

2012-01-01

Validating safety-critical real-time systems such as in-car networks often involves a model-based performance analysis of the network. An important issue performing such analysis is to provide precise model parameters, matching the actual equipment. One way to obtain such parameters is to derive...... them by measurements of the equipment. In this work we describe the design of a testbed enabling active measurements on up to 1 [Gb=Sec] Copper based Ethernet Switches. By use of the testbed it self, we conduct a series of tests where the precision of the testbed is estimated. We find a maximum error...

A comparison of back propagation and Generalized Regression Neural Networks performance in neutron spectrometry.

Science.gov (United States)

Martínez-Blanco, Ma Del Rosario; Ornelas-Vargas, Gerardo; Solís-Sánchez, Luis Octavio; Castañeda-Miranada, Rodrigo; Vega-Carrillo, Héctor René; Celaya-Padilla, José M; Garza-Veloz, Idalia; Martínez-Fierro, Margarita; Ortiz-Rodríguez, José Manuel

2016-11-01

The process of unfolding the neutron energy spectrum has been subject of research for many years. Monte Carlo, iterative methods, the bayesian theory, the principle of maximum entropy are some of the methods used. The drawbacks associated with traditional unfolding procedures have motivated the research of complementary approaches. Back Propagation Neural Networks (BPNN), have been applied with success in neutron spectrometry and dosimetry domains, however, the structure and learning parameters are factors that highly impact in the networks performance. In ANN domain, Generalized Regression Neural Network (GRNN) is one of the simplest neural networks in term of network architecture and learning algorithm. The learning is instantaneous, requiring no time for training. Opposite to BPNN, a GRNN would be formed instantly with just a 1-pass training on the development data. In the network development phase, the only hurdle is to optimize the hyper-parameter, which is known as sigma, governing the smoothness of the network. The aim of this work was to compare the performance of BPNN and GRNN in the solution of the neutron spectrometry problem. From results obtained it can be observed that despite the very similar results, GRNN performs better than BPNN. Copyright © 2016 Elsevier Ltd. All rights reserved.

International network connectivity and performance -- The challenge from high energy physics

Energy Technology Data Exchange (ETDEWEB)

Matthews, W.

2000-03-20

The requirements of the new generation of High Energy and Nuclear Physics (HENP) experiments such as the BaBar detector at the Stanford Linear Accelerator Center (SLAC), the Relativistic Heavy Ion Collider (RHIC) groups at the Brookhaven National Laboratory (BNL) and the LHC projects currently under development at the European Center for Particle Physics (CERN) are a huge challenge to networking. In order to increase understanding and to improve performance and connectivity by identifying bottlenecks and allocating resources, the HENP networking community has been actively monitoring the network for over five years.

Strategies for a better performance of RPL under mobility in wireless sensor networks

Science.gov (United States)

Latib, Z. A.; Jamil, A.; Alduais, N. A. M.; Abdullah, J.; Audah, L. H. M.; Alias, R.

2017-09-01

A Wireless Sensor Network (WSN) is usually stationary, which the network comprises of static nodes. The increase demand for mobility in various applications such as environmental monitoring, medical, home automation, and military, raises the question how IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) would perform under these mobility applications. This paper aims to understand performance of RPL and come out with strategies for a better performance of RPL in mobility scenarios. Because of this, this paper evaluates the performance of the RPL protocol under three different scenarios: sink and sensor nodes are static, static sink and mobile sensor nodes, and sink and sensor nodes are mobile. The network scenarios are implemented in Cooja simulator. A WSN consists of 25 sensor nodes and one sink node is configured in the simulation environment. The simulation is varied over different packet rates and ContikiMAC's Clear Channel Assessment (CCA) rate. As the performance metric, RPL is evaluated in term of packet delivery ratio (PDR), power consumption and packet rates. The simulation results show RPL provides a poor PDR in the mobility scenarios when compared to the static scenario. In addition, RPL consumes more power and increases duty-cycle rate to support mobility when compared to the static scenario. Based on the findings, we suggest three strategies for a better performance of RPL in mobility scenarios. First, RPL should operates at a lower packet rates when implemented in the mobility scenarios. Second, RPL should be implemented with a higher duty-cycle rate. Lastly, the sink node should be positioned as much as possible in the center of the mobile network.

Network embeddedness and organizational performance. The strength of strong ties in Dutch higher education

NARCIS (Netherlands)

Schalk, J.; Torenvlied, R.; Allen, J.P.

2010-01-01

With only few exceptions, current research in public management on the effects of inter-organizational networks on organizational performance focuses either on network activity or on the inter-organizational network structure. The present paper theoretically links both approaches and tests two

Organizing NPD networks for high innovation performance: the case of Dutch medical devices SMEs

NARCIS (Netherlands)

Pullen, A.J.J.; Groen, Arend J.; de Weerd-Nederhof, Petronella C.; Fisscher, O.A.M.

2010-01-01

This research examines which combination of network characteristics (the network configuration) leads to high innovation performance for small and medium sized companies (SMEs). Even though research has paid significant attention to the relation between the external network and the innovation

Performance Analysis of Space Information Networks with Backbone Satellite Relaying for Vehicular Networks

Directory of Open Access Journals (Sweden)

Jian Jiao

2017-01-01

Full Text Available Space Information Network (SIN with backbone satellites relaying for vehicular network (VN communications is regarded as an effective strategy to provide diverse vehicular services in a seamless, efficient, and cost-effective manner in rural areas and highways. In this paper, we investigate the performance of SIN return channel cooperative communications via an amplify-and-forward (AF backbone satellite relaying for VN communications, where we assume that both of the source-destination and relay-destination links undergo Shadowed-Rician fading and the source-relay link follows Rician fading, respectively. In this SIN-assisted VN communication scenario, we first obtain the approximate statistical distributions of the equivalent end-to-end signal-to-noise ratio (SNR of the system. Then, we derive the closed-form expressions to efficiently evaluate the average symbol error rate (ASER of the system. Furthermore, the ASER expressions are taking into account the effect of satellite perturbation of the backbone relaying satellite, which reveal the accumulated error of the antenna pointing error. Finally, simulation results are provided to verify the accuracy of our theoretical analysis and show the impact of various parameters on the system performance.

Performance of Implementation IBR-DTN and Batman-Adv Routing Protocol in Wireless Mesh Networks

Directory of Open Access Journals (Sweden)

Herman Yuliandoko

2016-03-01

Full Text Available Wireless mesh networks is a network which has high mobility and flexibility network. In Wireless mesh networks nodes are free to move and able to automatically build a network connection with other nodes. High mobility, heterogeneous condition and intermittent network connectivity cause data packets drop during wireless communication and it becomes a problem in the wireless mesh networks. This condition can happen because wireless mesh networks use connectionless networking type such as IP protocol which it is not tolerant to delay. To solve this condition it is needed a technology to keep data packets when the network is disconnect. Delay tolerant technology is a technology that provides store and forward mechanism and it can prevent packet data dropping during communication. In our research, we proposed a test bed wireless mesh networks implementation by using proactive routing protocol and combining with delay tolerant technology. We used Batman-adv routing protocol and IBR-DTN on our research. We measured some particular performance aspect of networking such as packet loss, delay, and throughput of the network. We identified that delay tolerant could keep packet data from dropping better than current wireless mesh networks in the intermittent network condition. We also proved that IBR-DTN and Batman-adv could run together on the wireless mesh networks. In The experiment throughput test result of IBR-DTN was higher than Current TCP on the LoS (Line of Side and on environment with obstacle. Keywords: Delay Tolerant, IBR-DTN, Wireless Mesh, Batman-adv, Performance

Copper nanofiber-networked cobalt oxide composites for high performance Li-ion batteries

Directory of Open Access Journals (Sweden)

Shim Hee-Sang

2011-01-01

Full Text Available Abstract We prepared a composite electrode structure consisting of copper nanofiber-networked cobalt oxide (CuNFs@CoO x . The copper nanofibers (CuNFs were fabricated on a substrate with formation of a network structure, which may have potential for improving electron percolation and retarding film deformation during the discharging/charging process over the electroactive cobalt oxide. Compared to bare CoO x thin-film (CoO x TF electrodes, the CuNFs@CoO x electrodes exhibited a significant enhancement of rate performance by at least six-fold at an input current density of 3C-rate. Such enhanced Li-ion storage performance may be associated with modified electrode structure at the nanoscale, improved charge transfer, and facile stress relaxation from the embedded CuNF network. Consequently, the CuNFs@CoO x composite structure demonstrated here can be used as a promising high-performance electrode for Li-ion batteries.

Comparison of Analytical and Measured Performance Results on Network Coding in IEEE 802.11 Ad-Hoc Networks

DEFF Research Database (Denmark)

Zhao, Fang; Médard, Muriel; Hundebøll, Martin

2012-01-01

CATWOMAN that can run on standard WiFi hardware. We present an analytical model to evaluate the performance of COPE in simple networks, and our results show the excellent predictive quality of this model. By closely examining the performance in two simple topologies, we observe that the coding gain results...

Predicting Subcontractor Performance Using Web-Based Evolutionary Fuzzy Neural Networks

Directory of Open Access Journals (Sweden)

Chien-Ho Ko

2013-01-01

Full Text Available Subcontractor performance directly affects project success. The use of inappropriate subcontractors may result in individual work delays, cost overruns, and quality defects throughout the project. This study develops web-based Evolutionary Fuzzy Neural Networks (EFNNs to predict subcontractor performance. EFNNs are a fusion of Genetic Algorithms (GAs, Fuzzy Logic (FL, and Neural Networks (NNs. FL is primarily used to mimic high level of decision-making processes and deal with uncertainty in the construction industry. NNs are used to identify the association between previous performance and future status when predicting subcontractor performance. GAs are optimizing parameters required in FL and NNs. EFNNs encode FL and NNs using floating numbers to shorten the length of a string. A multi-cut-point crossover operator is used to explore the parameter and retain solution legality. Finally, the applicability of the proposed EFNNs is validated using real subcontractors. The EFNNs are evolved using 22 historical patterns and tested using 12 unseen cases. Application results show that the proposed EFNNs surpass FL and NNs in predicting subcontractor performance. The proposed approach improves prediction accuracy and reduces the effort required to predict subcontractor performance, providing field operators with web-based remote access to a reliable, scientific prediction mechanism.

Predicting subcontractor performance using web-based Evolutionary Fuzzy Neural Networks.

Science.gov (United States)

Ko, Chien-Ho

2013-01-01

Subcontractor performance directly affects project success. The use of inappropriate subcontractors may result in individual work delays, cost overruns, and quality defects throughout the project. This study develops web-based Evolutionary Fuzzy Neural Networks (EFNNs) to predict subcontractor performance. EFNNs are a fusion of Genetic Algorithms (GAs), Fuzzy Logic (FL), and Neural Networks (NNs). FL is primarily used to mimic high level of decision-making processes and deal with uncertainty in the construction industry. NNs are used to identify the association between previous performance and future status when predicting subcontractor performance. GAs are optimizing parameters required in FL and NNs. EFNNs encode FL and NNs using floating numbers to shorten the length of a string. A multi-cut-point crossover operator is used to explore the parameter and retain solution legality. Finally, the applicability of the proposed EFNNs is validated using real subcontractors. The EFNNs are evolved using 22 historical patterns and tested using 12 unseen cases. Application results show that the proposed EFNNs surpass FL and NNs in predicting subcontractor performance. The proposed approach improves prediction accuracy and reduces the effort required to predict subcontractor performance, providing field operators with web-based remote access to a reliable, scientific prediction mechanism.

A novel nature inspired firefly algorithm with higher order neural network: Performance analysis

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Janmenjoy Nayak

2016-03-01

Full Text Available The applications of both Feed Forward Neural network and Multilayer perceptron are very diverse and saturated. But the linear threshold unit of feed forward networks causes fast learning with limited capabilities, while due to multilayering, the back propagation of errors exhibits slow training speed in MLP. So, a higher order network can be constructed by correlating between the input variables to perform nonlinear mapping using the single layer of input units for overcoming the above drawbacks. In this paper, a Firefly based higher order neural network has been proposed for data classification for maintaining fast learning and avoids the exponential increase of processing units. A vast literature survey has been conducted to review the state of the art of the previous developed models. The performance of the proposed method has been tested with various benchmark datasets from UCI machine learning repository and compared with the performance of other established models. Experimental results imply that the proposed method is fast, steady, reliable and provides better classification accuracy than others.

Dual Arm Work Package performance estimates and telerobot task network simulation

International Nuclear Information System (INIS)

Draper, J.V.

1997-01-01

This paper describes the methodology and results of a network simulation study of the Dual Arm Work Package (DAWP), to be employed for dismantling the Argonne National Laboratory CP-5 reactor. The development of the simulation model was based upon the results of a task analysis for the same system. This study was performed by the Oak Ridge National Laboratory (ORNL), in the Robotics and Process Systems Division. Funding was provided the US Department of Energy's Office of Technology Development, Robotics Technology Development Program (RTDP). The RTDP is developing methods of computer simulation to estimate telerobotic system performance. Data were collected to provide point estimates to be used in a task network simulation model. Three skilled operators performed six repetitions of a pipe cutting task representative of typical teleoperation cutting operations

Research Activity in Computational Physics utilizing High Performance Computing: Co-authorship Network Analysis

Science.gov (United States)

Ahn, Sul-Ah; Jung, Youngim

2016-10-01

The research activities of the computational physicists utilizing high performance computing are analyzed by bibliometirc approaches. This study aims at providing the computational physicists utilizing high-performance computing and policy planners with useful bibliometric results for an assessment of research activities. In order to achieve this purpose, we carried out a co-authorship network analysis of journal articles to assess the research activities of researchers for high-performance computational physics as a case study. For this study, we used journal articles of the Scopus database from Elsevier covering the time period of 2004-2013. We extracted the author rank in the physics field utilizing high-performance computing by the number of papers published during ten years from 2004. Finally, we drew the co-authorship network for 45 top-authors and their coauthors, and described some features of the co-authorship network in relation to the author rank. Suggestions for further studies are discussed.

Competitive Learning Neural Network Ensemble Weighted by Predicted Performance

Science.gov (United States)

Ye, Qiang

2010-01-01

Ensemble approaches have been shown to enhance classification by combining the outputs from a set of voting classifiers. Diversity in error patterns among base classifiers promotes ensemble performance. Multi-task learning is an important characteristic for Neural Network classifiers. Introducing a secondary output unit that receives different…

Road safety performance indicators for the interurban road network.

NARCIS (Netherlands)

Yannis, G. Weijermars, W.A.M. Gitelman, V. Vis, M. Chazirisa, A. Papadimitriou, E. & Lima Azevedo, C.

2013-01-01

Various road safety performance indicators (SPIs) have been proposed for different road safety research areas, mainly as regards driver behaviour (e.g. seat belt use, alcohol, drugs, etc.) and vehicles (e.g. passive safety); however, no SPIs for the road network and design have been developed. The

Integrated System for Performance Monitoring of ATLAS TDAQ Network

CERN Document Server

Savu, D; The ATLAS collaboration; Martin, B; Sjoen, R; Batraneanu, S; Stancu, S

2010-01-01

The ATLAS TDAQ Network consists of three separate networks spanning four levels of the experimental building. Over 200 edge switches and 5 multi-blade chassis routers are used to interconnect 2000 processors, adding up to more than 7000 high speed interfaces. In order to substantially speed-up ad-hoc and post mortem analysis, a scalable, yet flexible, integrated system for monitoring both network statistics and environmental conditions, processor parameters and data taking characteristics was required. For successful up-to-the-minute monitoring, information from many SNMP compliant devices, independent databases and custom APIs was gathered, stored and displayed in an optimal way. Easy navigation and compact aggregation of multiple data sources were the main requirements; characteristics not found in any of the tested products, either open-source or commercial. This paper describes how performance, scalability and display issues were addressed and what challenges the project faced during development and deplo...

Parameter Selection and Performance Comparison of Particle Swarm Optimization in Sensor Networks Localization.

Science.gov (United States)

Cui, Huanqing; Shu, Minglei; Song, Min; Wang, Yinglong

2017-03-01

Localization is a key technology in wireless sensor networks. Faced with the challenges of the sensors' memory, computational constraints, and limited energy, particle swarm optimization has been widely applied in the localization of wireless sensor networks, demonstrating better performance than other optimization methods. In particle swarm optimization-based localization algorithms, the variants and parameters should be chosen elaborately to achieve the best performance. However, there is a lack of guidance on how to choose these variants and parameters. Further, there is no comprehensive performance comparison among particle swarm optimization algorithms. The main contribution of this paper is three-fold. First, it surveys the popular particle swarm optimization variants and particle swarm optimization-based localization algorithms for wireless sensor networks. Secondly, it presents parameter selection of nine particle swarm optimization variants and six types of swarm topologies by extensive simulations. Thirdly, it comprehensively compares the performance of these algorithms. The results show that the particle swarm optimization with constriction coefficient using ring topology outperforms other variants and swarm topologies, and it performs better than the second-order cone programming algorithm.

Parameter Selection and Performance Comparison of Particle Swarm Optimization in Sensor Networks Localization

Directory of Open Access Journals (Sweden)

Huanqing Cui

2017-03-01

Full Text Available Localization is a key technology in wireless sensor networks. Faced with the challenges of the sensors’ memory, computational constraints, and limited energy, particle swarm optimization has been widely applied in the localization of wireless sensor networks, demonstrating better performance than other optimization methods. In particle swarm optimization-based localization algorithms, the variants and parameters should be chosen elaborately to achieve the best performance. However, there is a lack of guidance on how to choose these variants and parameters. Further, there is no comprehensive performance comparison among particle swarm optimization algorithms. The main contribution of this paper is three-fold. First, it surveys the popular particle swarm optimization variants and particle swarm optimization-based localization algorithms for wireless sensor networks. Secondly, it presents parameter selection of nine particle swarm optimization variants and six types of swarm topologies by extensive simulations. Thirdly, it comprehensively compares the performance of these algorithms. The results show that the particle swarm optimization with constriction coefficient using ring topology outperforms other variants and swarm topologies, and it performs better than the second-order cone programming algorithm.

Análise da eficiência espectral para bandas licenciadas WiMAX considerando a duplexação e o perfil de tráfego

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Márcia Maria Savoine

2012-11-01

Full Text Available Este trabalho apresenta a comparação efetuada por meio de simulações de eventos discretos, realizadas com o software ARENA, das técnicas de Duplexação por Divisão no Tempo (TDD e Duplexação por Divisão da Freqüência (FDD, técnicas presentes no padrão IEEE 802.16 e utilizadas pelo WiMAX nos canais bidirecionais de uplink e downlink. O modelo de simulação considerou na fila de chegada dos serviços o conceito FIFO e as simulações foram realizadas considerando cinco aplicações (Streaming, Download, Web, E-mail e Small-Transaction para downlink e uplink. O parâmetro de eficiência considerado foi o número mínimo de canais necessário em cada um dos canais padrões. A análise efetuada permitiu identificar, dada estas condições de tráfego, qual das técnicas seria a mais indicada. Constatou-se ainda que em tráfego de dados assimétricos a técnica TDD se apresentou mais eficiente e, observou-se existir ociosidade de espectro na técnica FDD.

An enhanced performance through agent-based secure approach for mobile ad hoc networks

Science.gov (United States)

Bisen, Dhananjay; Sharma, Sanjeev

2018-01-01

This paper proposes an agent-based secure enhanced performance approach (AB-SEP) for mobile ad hoc network. In this approach, agent nodes are selected through optimal node reliability as a factor. This factor is calculated on the basis of node performance features such as degree difference, normalised distance value, energy level, mobility and optimal hello interval of node. After selection of agent nodes, a procedure of malicious behaviour detection is performed using fuzzy-based secure architecture (FBSA). To evaluate the performance of the proposed approach, comparative analysis is done with conventional schemes using performance parameters such as packet delivery ratio, throughput, total packet forwarding, network overhead, end-to-end delay and percentage of malicious detection.

Passive and Active Monitoring on a High Performance Research Network

International Nuclear Information System (INIS)

Matthews, Warren

2001-01-01

The bold network challenges described in ''Internet End-to-end Performance Monitoring for the High Energy and Nuclear Physics Community'' presented at PAM 2000 have been tackled by the intrepid administrators and engineers providing the network services. After less than a year, the BaBar collaboration has collected almost 100 million particle collision events in a database approaching 165TB (Tera=10 12 ). Around 20TB has been exported via the Internet to the BaBar regional center at IN2P3 in Lyon, France, for processing and around 40 TB of simulated events have been imported to SLAC from Lawrence Livermore National Laboratory (LLNL). An unforseen challenge has arisen due to recent events and highlighted security concerns at DoE funded labs. New rules and regulations suggest it is only a matter of time before many active performance measurements may not be possible between many sites. Yet, at the same time, the importance of understanding every aspect of the network and eradicating packet loss for high throughput data transfers has become apparent. Work at SLAC to employ passive monitoring using netflow and OC3MON is underway and techniques to supplement and possibly replace the active measurements are being considered. This paper will detail the special needs and traffic characterization of a remarkable research project, and how the networking hurdles have been resolved (or not) to achieve the required high data throughput. Results from active and passive measurements will be compared, and methods for achieving high throughput and the effect on the network will be assessed along with tools that directly measure throughput and applications used to actually transfer data

Passive and Active Monitoring on a High Performance Research Network.

Energy Technology Data Exchange (ETDEWEB)

Matthews, Warren

2001-05-01

The bold network challenges described in ''Internet End-to-end Performance Monitoring for the High Energy and Nuclear Physics Community'' presented at PAM 2000 have been tackled by the intrepid administrators and engineers providing the network services. After less than a year, the BaBar collaboration has collected almost 100 million particle collision events in a database approaching 165TB (Tera=10{sup 12}). Around 20TB has been exported via the Internet to the BaBar regional center at IN2P3 in Lyon, France, for processing and around 40 TB of simulated events have been imported to SLAC from Lawrence Livermore National Laboratory (LLNL). An unforseen challenge has arisen due to recent events and highlighted security concerns at DoE funded labs. New rules and regulations suggest it is only a matter of time before many active performance measurements may not be possible between many sites. Yet, at the same time, the importance of understanding every aspect of the network and eradicating packet loss for high throughput data transfers has become apparent. Work at SLAC to employ passive monitoring using netflow and OC3MON is underway and techniques to supplement and possibly replace the active measurements are being considered. This paper will detail the special needs and traffic characterization of a remarkable research project, and how the networking hurdles have been resolved (or not!) to achieve the required high data throughput. Results from active and passive measurements will be compared, and methods for achieving high throughput and the effect on the network will be assessed along with tools that directly measure throughput and applications used to actually transfer data.

Performance Analysis with Network-Enhanced Complexities: On Fading Measurements, Event-Triggered Mechanisms, and Cyber Attacks

Directory of Open Access Journals (Sweden)

Derui Ding

2014-01-01

Full Text Available Nowadays, the real-world systems are usually subject to various complexities such as parameter uncertainties, time-delays, and nonlinear disturbances. For networked systems, especially large-scale systems such as multiagent systems and systems over sensor networks, the complexities are inevitably enhanced in terms of their degrees or intensities because of the usage of the communication networks. Therefore, it would be interesting to (1 examine how this kind of network-enhanced complexities affects the control or filtering performance; and (2 develop some suitable approaches for controller/filter design problems. In this paper, we aim to survey some recent advances on the performance analysis and synthesis with three sorts of fashionable network-enhanced complexities, namely, fading measurements, event-triggered mechanisms, and attack behaviors of adversaries. First, these three kinds of complexities are introduced in detail according to their engineering backgrounds, dynamical characteristic, and modelling techniques. Then, the developments of the performance analysis and synthesis issues for various networked systems are systematically reviewed. Furthermore, some challenges are illustrated by using a thorough literature review and some possible future research directions are highlighted.

The impacts of network competence, knowledge sharing on service innovation performance: Moderating role of relationship quality

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Zaoquan Jian

2013-03-01

Full Text Available Purpose: To examine how network competence, knowledge sharing and relationship quality affect service innovation performanceDesign/methodology/approach: Empirical ResearchFindings: 1 Both enterprise’s network competence and knowledge sharing have distinct positive impact on SIP; (2 Knowledge sharing partially mediates the effect of network competence on SIP. (3 Relationship quality positively moderates the effect of network competence on knowledge sharing, and the effect of knowledge sharing on SIP. (4 Relationship quality does not positively moderate the effect of network competence on SIP.Originality/value: This study has enriched current understanding of the relationship among network competence, knowledge sharing, relationship quality and service innovation performance.

Performance evaluation of multi-stratum resources optimization with network functions virtualization for cloud-based radio over optical fiber networks.

Science.gov (United States)

Yang, Hui; He, Yongqi; Zhang, Jie; Ji, Yuefeng; Bai, Wei; Lee, Young

2016-04-18

Cloud radio access network (C-RAN) has become a promising scenario to accommodate high-performance services with ubiquitous user coverage and real-time cloud computing using cloud BBUs. In our previous work, we implemented cross stratum optimization of optical network and application stratums resources that allows to accommodate the services in optical networks. In view of this, this study extends to consider the multiple dimensional resources optimization of radio, optical and BBU processing in 5G age. We propose a novel multi-stratum resources optimization (MSRO) architecture with network functions virtualization for cloud-based radio over optical fiber networks (C-RoFN) using software defined control. A global evaluation scheme (GES) for MSRO in C-RoFN is introduced based on the proposed architecture. The MSRO can enhance the responsiveness to dynamic end-to-end user demands and globally optimize radio frequency, optical and BBU resources effectively to maximize radio coverage. The efficiency and feasibility of the proposed architecture are experimentally demonstrated on OpenFlow-based enhanced SDN testbed. The performance of GES under heavy traffic load scenario is also quantitatively evaluated based on MSRO architecture in terms of resource occupation rate and path provisioning latency, compared with other provisioning scheme.

Wireless network simulation - Your window on future network performance

NARCIS (Netherlands)

Fledderus, E.

2005-01-01

The paper describes three relevant perspectives on current wireless simulation practices. In order to obtain the key challenges for future network simulations, the characteristics of "beyond 3G" networks are described, including their impact on simulation.

High Performance Data mining by Genetic Neural Network

Directory of Open Access Journals (Sweden)

Dadmehr Rahbari

2013-10-01

Full Text Available Data mining in computer science is the process of discovering interesting and useful patterns and relationships in large volumes of data. Most methods for mining problems is based on artificial intelligence algorithms. Neural network optimization based on three basic parameters topology, weights and the learning rate is a powerful method. We introduce optimal method for solving this problem. In this paper genetic algorithm with mutation and crossover operators change the network structure and optimized that. Dataset used for our work is stroke disease with twenty features that optimized number of that achieved by new hybrid algorithm. Result of this work is very well incomparison with other similar method. Low present of error show that our method is our new approach to efficient, high-performance data mining problems is introduced.

On end-to-end performance of MIMO multiuser in cognitive radio networks

KAUST Repository

Yang, Yuli

2011-12-01

In this paper, a design for the multiple-input-multiple-output (MIMO) multiuser transmission in the cognitive radio network is developed and its end-to-end performance is investigated under spectrum-sharing constraints. Firstly, the overall average packet error rate is analyzed by considering the channel state information feedback delay and the multiuser scheduling. Then, we provide corresponding numerical results to measure the performance evaluation for several separate scenarios, which presents a convenient tool for the cognitive radio network design with multiple secondary MIMO users. © 2011 IEEE.

On end-to-end performance of MIMO multiuser in cognitive radio networks

KAUST Repository

Yang, Yuli; Aissa, Sonia

2011-01-01

In this paper, a design for the multiple-input-multiple-output (MIMO) multiuser transmission in the cognitive radio network is developed and its end-to-end performance is investigated under spectrum-sharing constraints. Firstly, the overall average packet error rate is analyzed by considering the channel state information feedback delay and the multiuser scheduling. Then, we provide corresponding numerical results to measure the performance evaluation for several separate scenarios, which presents a convenient tool for the cognitive radio network design with multiple secondary MIMO users. © 2011 IEEE.

Performance Evaluation of Moving Small-Cell Network with Proactive Cache

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Young Min Kwon

2016-01-01

Full Text Available Due to rapid growth in mobile traffic, mobile network operators (MNOs are considering the deployment of moving small-cells (mSCs. mSC is a user-centric network which provides voice and data services during mobility. mSC can receive and forward data traffic via wireless backhaul and sidehaul links. In addition, due to the predictive nature of users demand, mSCs can proactively cache the predicted contents in off-peak-traffic periods. Due to these characteristics, MNOs consider mSCs as a cost-efficient solution to not only enhance the system capacity but also provide guaranteed quality of service (QoS requirements to moving user equipment (UE in peak-traffic periods. In this paper, we conduct extensive system level simulations to analyze the performance of mSCs with varying cache size and content popularity and their effect on wireless backhaul load. The performance evaluation confirms that the QoS of moving small-cell UE (mSUE notably improves by using mSCs together with proactive caching. We also show that the effective use of proactive cache significantly reduces the wireless backhaul load and increases the overall network capacity.

High performance all-carbon composite transparent electrodes containing uniform carbon nanotube networks

Energy Technology Data Exchange (ETDEWEB)

Yun, Hyung Duk; Kwak, Jinsung; Kim, Se-Yang [School of Materials Science and Engineering & Low-Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 (Korea, Republic of); Seo, Han; Bang, In Cheol; Kim, Sung Youb [School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 (Korea, Republic of); Kang, Seoktae [Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141 (Korea, Republic of); Kwon, Soon-Yong, E-mail: sykwon@unist.ac.kr [School of Materials Science and Engineering & Low-Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 (Korea, Republic of); School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 (Korea, Republic of)

2016-08-05

Indium tin oxide-free, flexible transparent electrodes (TEs) are crucial for the future commercialization of flexible and wearable electronics. While carbon-based TEs containing carbon nanotube (CNT) networks show promise, they usually exhibit poor dispersion properties, limiting their performance and practicality. In this study, we report a highly efficient and bending durable all-carbon composite TE (ac-TE) that employs uniform CNT networks on a monolayer graphene/polyethylene terephthalate (PET) substrate via a simple air spray deposition method. The air-sprayed CNT/graphene assembly was free-standing on solution, making a polymer-free transfer of carbon composites to target substrates possible. The excellent performance of the ac-TEs was attributed to the uniformly networked CNTs on the polycrystalline graphene with a well-controlled density, effectively bridging the line defects and filling the tears/voids or folds necessarily existing in the as-processed graphene. The sheet resistance of the ac-TEs was increased only 6% from its original value at a bending radius of 2.7 mm, while that of the pristine graphene/PET assembly increased 237%. Mechanical bending of the ac-TEs worsened the electrical performance by only ∼1.7% after 2000 bending cycles at a bending radius of 2.5 mm. Degradation of the performance by the bending was the result of line defects formation in the graphene, demonstrating the potential of the uniform CNT networks to achieve more efficient and flexible carbon-based TEs. Furthermore, the chemically-doped ac-TEs showed commercially suitable electronic and optical properties with much enhanced thermal stability, closer to practical TEs in flexible devices. - Highlights: • Highly efficient and bending durable all-carbon composite transparent electrodes (TEs) are designed. • The performance was strongly dependent on morphology of CNT networks on graphene. • The mechanism relies on the defect reductions in graphene by uniform CNT coating

High performance all-carbon composite transparent electrodes containing uniform carbon nanotube networks

International Nuclear Information System (INIS)

Yun, Hyung Duk; Kwak, Jinsung; Kim, Se-Yang; Seo, Han; Bang, In Cheol; Kim, Sung Youb; Kang, Seoktae; Kwon, Soon-Yong

2016-01-01

Indium tin oxide-free, flexible transparent electrodes (TEs) are crucial for the future commercialization of flexible and wearable electronics. While carbon-based TEs containing carbon nanotube (CNT) networks show promise, they usually exhibit poor dispersion properties, limiting their performance and practicality. In this study, we report a highly efficient and bending durable all-carbon composite TE (ac-TE) that employs uniform CNT networks on a monolayer graphene/polyethylene terephthalate (PET) substrate via a simple air spray deposition method. The air-sprayed CNT/graphene assembly was free-standing on solution, making a polymer-free transfer of carbon composites to target substrates possible. The excellent performance of the ac-TEs was attributed to the uniformly networked CNTs on the polycrystalline graphene with a well-controlled density, effectively bridging the line defects and filling the tears/voids or folds necessarily existing in the as-processed graphene. The sheet resistance of the ac-TEs was increased only 6% from its original value at a bending radius of 2.7 mm, while that of the pristine graphene/PET assembly increased 237%. Mechanical bending of the ac-TEs worsened the electrical performance by only ∼1.7% after 2000 bending cycles at a bending radius of 2.5 mm. Degradation of the performance by the bending was the result of line defects formation in the graphene, demonstrating the potential of the uniform CNT networks to achieve more efficient and flexible carbon-based TEs. Furthermore, the chemically-doped ac-TEs showed commercially suitable electronic and optical properties with much enhanced thermal stability, closer to practical TEs in flexible devices. - Highlights: • Highly efficient and bending durable all-carbon composite transparent electrodes (TEs) are designed. • The performance was strongly dependent on morphology of CNT networks on graphene. • The mechanism relies on the defect reductions in graphene by uniform CNT coating

Strategies of Yota (Scartel - 4G Operator in Russian Federation

Directory of Open Access Journals (Sweden)

Netra Pal Singh

2013-12-01

Full Text Available Russian Federation is one of the high growth markets for telecom services which are expected to reach $48.5 billion by 2013.  With the granting of 4G LTE licenses, it is expected that 4G market in Russian Federation will be dominated by four cellular operators, i.e., MTS, Beeline, and MegaFon, Rostelecom along with two new startups, i.e., Osnova Telecom and Red Telecom (Iladi (2010. In addition, other companies such as Yota, Synterra, COMSTAR, Freshtel etc. are also operating in Russian WiMax & LTE telecom market to provide similar services. This paper is an attempt to analyze some of the parameters of LTE turn Yota WiMax Telecom Operator in Russian Federation. The paper covers current achievements of Yota, its reach in Russian Federation, its network size & technology, its services, expansion plans for future, strategies for survival (in question in a highly competitive market of big companies, and its ultimate fate.

Performance Evaluation of Hadoop-based Large-scale Network Traffic Analysis Cluster

Directory of Open Access Journals (Sweden)

Tao Ran

2016-01-01

Full Text Available As Hadoop has gained popularity in big data era, it is widely used in various fields. The self-design and self-developed large-scale network traffic analysis cluster works well based on Hadoop, with off-line applications running on it to analyze the massive network traffic data. On purpose of scientifically and reasonably evaluating the performance of analysis cluster, we propose a performance evaluation system. Firstly, we set the execution times of three benchmark applications as the benchmark of the performance, and pick 40 metrics of customized statistical resource data. Then we identify the relationship between the resource data and the execution times by a statistic modeling analysis approach, which is composed of principal component analysis and multiple linear regression. After training models by historical data, we can predict the execution times by current resource data. Finally, we evaluate the performance of analysis cluster by the validated predicting of execution times. Experimental results show that the predicted execution times by trained models are within acceptable error range, and the evaluation results of performance are accurate and reliable.

Structure-function relationships in elderly resting-state-networks : influence of age and cognitive performance

OpenAIRE

Jockwitz, Christiane

2016-01-01

The aim of this work was to investigate the structure-function relationship in cognitive resting state networks in a large population-based elderly sample. The first study characterized the functional connectivity in four cognitive resting state networks with respect to age, gender and cognitive performance: Default Mode Network (DMN), executive, and left and right frontoparietal resting state networks. The second study assessed the structural correlates of the functional reorganization of th...

Impact of Business Interoperability on the Performance of Complex Cooperative Supply Chain Networks: A Case Study

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Izunildo Cabral

2018-01-01

Full Text Available This paper proposes an agent-based model for evaluating the effect of business interoperability on the performance of cooperative supply chain networks. The model is based on insights from the Industrial Marketing and Purchasing network approach and the complex systems theory perspective. To demonstrate its applicability, an explanatory case study regarding a Portuguese reverse logistics cooperative supply chain network is presented. Face-to-face interviews and forms were used to collect data. The findings show that the establishment of appropriate levels of business interoperability has helped to reduce several non-value-added interaction processes and consequently improve the operational performance of the Valorpneu network. Regarding the research implications, this paper extends the current knowledge on business interoperability and an important problem in business: how business interoperability gaps in dyadic organizational relationships affect the network of companies that the two companies belong to—network effect. In terms of practical implications, managers can use the proposed model as a starting point to simulate complex interactions between supply chain network partners and understand better how the performance of their networks emerges from these interactions and from the adoption of different levels of business interoperability.

The Banat seismic network: Evolution and performance

International Nuclear Information System (INIS)

Oros, E.

2002-01-01

In the Banat Seismic Region, with its important seismogenic zones (Banat and Danube), operates today the Banat Seismic Network. This network has four short period seismic stations telemetered at the Timisoara Seismological Observatory (since 1995): Siria, Banloc, Buzias and Timisoara. The stations are equipped with short-period S13 seismometers (1 second). The data recorded by the short-period stations are telemetered to Timisoara where they are digitized at 50 samples per second, with 16 bit resolution. At Timisoara works SAPS, an automated system for data acquisition and processing, which performs real-time event detection (based on Allen algorithm), discrimination between local and teleseismic events, automatic P and S waves picking, location and magnitude determination for local events and teleseisms, 'feeding' of an Automatic Data Request Manager with phases, locations and waveforms, sending of earthquake information (as phases and location), by e-mail to Bucharest. The beginning of the seismological observations in Banat is in the 1880's (Timisoara Meteorological Observatory). The first seismograph was installed in Timisoara in 1901, and its systematic observations began in 1902. The World War I interrupted its work. In 1942 Prof. I. Curea founded the Seismic Station Timisoara, and since 1967 until today this station worked into a special building. After 1972 two stations with high amplification were installed in Retezat Mts (Gura Zlata) and on Nera Valey (Susara), as a consequence of the research results. Since 1982 Buzias station began to work completing the Banat Seismic Network. Therefore, the network could detect and locate any local seismic event with M > 2.2. Moreover, up to 20 km distance from each station any seismic event could be detected over M = 0.5. The paper also presents the quality of the locations versus different local seismic sources. (author)

Motor network structure and function are associated with motor performance in Huntington's disease.

Science.gov (United States)

Müller, Hans-Peter; Gorges, Martin; Grön, Georg; Kassubek, Jan; Landwehrmeyer, G Bernhard; Süßmuth, Sigurd D; Wolf, Robert Christian; Orth, Michael

2016-03-01

In Huntington's disease, the relationship of brain structure, brain function and clinical measures remains incompletely understood. We asked how sensory-motor network brain structure and neural activity relate to each other and to motor performance. Thirty-four early stage HD and 32 age- and sex-matched healthy control participants underwent structural magnetic resonance imaging (MRI), diffusion tensor, and intrinsic functional connectivity MRI. Diffusivity patterns were assessed in the cortico-spinal tract and the thalamus-somatosensory cortex tract. For the motor network connectivity analyses the dominant M1 motor cortex region and for the basal ganglia-thalamic network the thalamus were used as seeds. Region to region structural and functional connectivity was examined between thalamus and somatosensory cortex. Fractional anisotropy (FA) was higher in HD than controls in the basal ganglia, and lower in the external and internal capsule, in the thalamus, and in subcortical white matter. Between-group axial and radial diffusivity differences were more prominent than differences in FA, and correlated with motor performance. Within the motor network, the insula was less connected in HD than in controls, with the degree of connection correlating with motor scores. The basal ganglia-thalamic network's connectivity differed in the insula and basal ganglia. Tract specific white matter diffusivity and functional connectivity were not correlated. In HD sensory-motor white matter organization and functional connectivity in a motor network were independently associated with motor performance. The lack of tract-specific association of structure and function suggests that functional adaptation to structural loss differs between participants.

DASH-based network performance-aware solution for personalised video delivery systems

OpenAIRE

Rovcanin, Lejla

2016-01-01

Video content is an increasingly prevalent contributor of Internet traffic. The proliferation of available video content has been fuelled by both Internet expansion and the growing power and affordability of viewing devices. Such content can be consumed anywhere and anytime, using a variety of technologies. The high data rates required for streaming video content and the large volume of requests for such content degrade network performance when devices compete for finite network bandwidth. Th...

Performance Analysis of a Cluster-Based MAC Protocol for Wireless Ad Hoc Networks

Directory of Open Access Journals (Sweden)

Jesús Alonso-Zárate

2010-01-01

Full Text Available An analytical model to evaluate the non-saturated performance of the Distributed Queuing Medium Access Control Protocol for Ad Hoc Networks (DQMANs in single-hop networks is presented in this paper. DQMAN is comprised of a spontaneous, temporary, and dynamic clustering mechanism integrated with a near-optimum distributed queuing Medium Access Control (MAC protocol. Clustering is executed in a distributed manner using a mechanism inspired by the Distributed Coordination Function (DCF of the IEEE 802.11. Once a station seizes the channel, it becomes the temporary clusterhead of a spontaneous cluster and it coordinates the peer-to-peer communications between the clustermembers. Within each cluster, a near-optimum distributed queuing MAC protocol is executed. The theoretical performance analysis of DQMAN in single-hop networks under non-saturation conditions is presented in this paper. The approach integrates the analysis of the clustering mechanism into the MAC layer model. Up to the knowledge of the authors, this approach is novel in the literature. In addition, the performance of an ad hoc network using DQMAN is compared to that obtained when using the DCF of the IEEE 802.11, as a benchmark reference.

Is a Responsive Default Mode Network Required for Successful Working Memory Task Performance?

Science.gov (United States)

Čeko, Marta; Gracely, John L; Fitzcharles, Mary-Ann; Seminowicz, David A; Schweinhardt, Petra; Bushnell, M Catherine

2015-08-19

In studies of cognitive processing using tasks with externally directed attention, regions showing increased (external-task-positive) and decreased or "negative" [default-mode network (DMN)] fMRI responses during task performance are dynamically responsive to increasing task difficulty. Responsiveness (modulation of fMRI signal by increasing load) has been linked directly to successful cognitive task performance in external-task-positive regions but not in DMN regions. To investigate whether a responsive DMN is required for successful cognitive performance, we compared healthy human subjects (n = 23) with individuals shown to have decreased DMN engagement (chronic pain patients, n = 28). Subjects performed a multilevel working-memory task (N-back) during fMRI. If a responsive DMN is required for successful performance, patients having reduced DMN responsiveness should show worsened performance; if performance is not reduced, their brains should show compensatory activation in external-task-positive regions or elsewhere. All subjects showed decreased accuracy and increased reaction times with increasing task level, with no significant group differences on either measure at any level. Patients had significantly reduced negative fMRI response (deactivation) of DMN regions (posterior cingulate/precuneus, medial prefrontal cortex). Controls showed expected modulation of DMN deactivation with increasing task difficulty. Patients showed significantly reduced modulation of DMN deactivation by task difficulty, despite their successful task performance. We found no evidence of compensatory neural recruitment in external-task-positive regions or elsewhere. Individual responsiveness of the external-task-positive ventrolateral prefrontal cortex, but not of DMN regions, correlated with task accuracy. These findings suggest that a responsive DMN may not be required for successful cognitive performance; a responsive external-task-positive network may be sufficient. We studied the

Security measures effect over performance in service provider network

African Journals Online (AJOL)

pc

2018-03-05

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

Performance assessment and Self-Organisation of Virtual Sectorisation in a realistic LTE network

NARCIS (Netherlands)

Martinez, A.M.; Trichias, K.; Litjens, R.

2016-01-01

Active Antenna Systems (AAS) technology is one of several advanced features that enable a mobile network operator to cost-efficiently increase its network capacity to cope with the exponential mobile data traffic growth and the ever more demanding performance requirements. AAS can be exploited to

An ANP-based network to measure the impact of Lean production on organisational performance

Directory of Open Access Journals (Sweden)

José Luis Ruano Pérez

2018-04-01

Full Text Available Purpose: The main objective of this research is to design a decision-making network, based on the Analytic Network Process (ANP technique (Saaty, 1996, which will include the main elements to take into account when stating the effect that the application of LP techniques has got on the performance of an organisation, measured this through a Performance Measurement System (PMS. Design/methodology/approach: The authors have carried out a scientific literature search to state what the main LP techniques are –and how to group them into different clusters- and have then applied the ANP, its first phase, in order to design the decisional network. Findings: There is a gap in the literature when trying to identify and quantify to what extent the implementation of LP techniques affects to organisational performance. The ANP is an appropriate technique to do so due to the need of gathering and quantifying experts’ opinions. Originality/value: The designed ANP-based network to measure the impact of LP over organisational performance is a novel approach. This paper justifies its usage and paves the way to implement the rest of the ANP phases in future research work.

Network and User-Perceived Performance of Web Page Retrievals

Science.gov (United States)

Kruse, Hans; Allman, Mark; Mallasch, Paul

1998-01-01

The development of the HTTP protocol has been driven by the need to improve the network performance of the protocol by allowing the efficient retrieval of multiple parts of a web page without the need for multiple simultaneous TCP connections between a client and a server. We suggest that the retrieval of multiple page elements sequentially over a single TCP connection may result in a degradation of the perceived performance experienced by the user. We attempt to quantify this perceived degradation through the use of a model which combines a web retrieval simulation and an analytical model of TCP operation. Starting with the current HTTP/l.1 specification, we first suggest a client@side heuristic to improve the perceived transfer performance. We show that the perceived speed of the page retrieval can be increased without sacrificing data transfer efficiency. We then propose a new client/server extension to the HTTP/l.1 protocol to allow for the interleaving of page element retrievals. We finally address the issue of the display of advertisements on web pages, and in particular suggest a number of mechanisms which can make efficient use of IP multicast to send advertisements to a number of clients within the same network.

Think different? An investigation of network antecedents and performance consequences of creativity as deviation

OpenAIRE

Soda, Giuseppe; Bizzi, Lorenzo

2012-01-01

In this study, we investigate how network relations affect project performance through creativity. We challenge previous conceptualizations of creativity by proposing the idea that creative outcomes in project industries can be conceptualized as deviation from past projects and deviation from partners’ projects. While previous research has mostly assumed that network relations are beneficial to performance because they increase innovation and creativity, our conceptualization of creativity al...

VMware vSphere performance designing CPU, memory, storage, and networking for performance-intensive workloads

CERN Document Server

Liebowitz, Matt; Spies, Rynardt

2014-01-01

Covering the latest VMware vSphere software, an essential book aimed at solving vSphere performance problems before they happen VMware vSphere is the industry's most widely deployed virtualization solution. However, if you improperly deploy vSphere, performance problems occur. Aimed at VMware administrators and engineers and written by a team of VMware experts, this resource provides guidance on common CPU, memory, storage, and network-related problems. Plus, step-by-step instructions walk you through techniques for solving problems and shed light on possible causes behind the problems. Divu

Performance analysis of selective cooperation in underlay cognitive networks over Rayleigh channels

KAUST Repository

Hussain, Syed Imtiaz

2011-06-01

Underlay cognitive networks should follow strict interference thresholds to operate in parallel with primary networks. This constraint limits their transmission power and eventually the area of coverage. Therefore, it is very likely that the underlay networks will make use of relays to transmit signals to the distant secondary users. In this paper, we propose a secondary relay selection scheme which maximizes the end-to-end signal to noise ratio (SNR) for the secondary link while keeping the interference levels to the primary network below a certain threshold. We derive closed form expressions for the probability density function (PDF) of the SNR at the secondary destination, average bit error probability and outage probability. Analytical results are verified through simulations which also give insight about the benefits and tradeoffs of the selective cooperation in underlay cognitive networks. It is shown that, in contrast to non-cognitive selective cooperation, this scheme performs better in low SNR region for cognitive networks. © 2011 IEEE.

Entrepreneurial orientation and new venture performance : The mediating effect of network strategies

NARCIS (Netherlands)

Stam, Wouter; Elfring, T.

2006-01-01

While entrepreneurship scholars have generally examined the direct effects of entrepreneurial orientation (EO) on the performance of new ventures, we build on recent calls for a contingency framework and propose that ventures' network strategies intervene in the EO-performance relationship. Drawing

Performance evaluation of distributed wavelength assignment in WDM optical networks

Science.gov (United States)

Hashiguchi, Tomohiro; Wang, Xi; Morikawa, Hiroyuki; Aoyama, Tomonori

2004-04-01

In WDM wavelength routed networks, prior to a data transfer, a call setup procedure is required to reserve a wavelength path between the source-destination node pairs. A distributed approach to a connection setup can achieve a very high speed, while improving the reliability and reducing the implementation cost of the networks. However, along with many advantages, several major challenges have been posed by the distributed scheme in how the management and allocation of wavelength could be efficiently carried out. In this thesis, we apply a distributed wavelength assignment algorithm named priority based wavelength assignment (PWA) that was originally proposed for the use in burst switched optical networks to the problem of reserving wavelengths of path reservation protocols in the distributed control optical networks. Instead of assigning wavelengths randomly, this approach lets each node select the "safest" wavelengths based on the information of wavelength utilization history, thus unnecessary future contention is prevented. The simulation results presented in this paper show that the proposed protocol can enhance the performance of the system without introducing any apparent drawbacks.

Microwave synthesis of copper network onto lithium iron phosphate cathode materials for improved electrochemical performance

Energy Technology Data Exchange (ETDEWEB)

Hsieh, Chien-Te, E-mail: cthsieh@saturn.yzu.edu.tw [Department of Chemical Engineering and Materials Science, Yuan Ze University, Taoyuan 320, Taiwan (China); Liu, Juan-Ru [Department of Chemical Engineering and Materials Science, Yuan Ze University, Taoyuan 320, Taiwan (China); Juang, Ruey-Shin [Department of Chemical and Materials Engineering, Chang Gung University, Taoyuan 333, Taiwan (China); Lee, Cheng-En; Chen, Yu-Fu [Department of Chemical Engineering and Materials Science, Yuan Ze University, Taoyuan 320, Taiwan (China)

2015-03-01

Herein reported is an efficient microwave-assisted (MA) approach for growing Cu network onto LiFePO{sub 4} (LFP) powders as cathode materials for high-performance Li-ion batteries. The MA approach is capable of depositing highly-porous Cu network, fully covered the LFP powders. The electrochemical performance of Cu-coated LFP cathodes are well characterized by charge/discharge cycling and electrochemical impedance spectroscopy (EIS). The Cu network acts as the key role in improving the specific capacity, rate capability, electrode polarization, as compared to fresh LFP cathode without the Cu coating. The EIS incorporated with equivalent circuit reveals that the completed Cu network obviously suppresses the charge transfer resistance. This result can be attributed to the fact that the Cu network ensures the LFP crystals to get electron easily, alleviating the electrode polarization in view of one-dimensional Li{sup +} ion mobility in the olivine crystals. Based on the analysis of Randles plots, the relatively higher Li{sup +} diffusion coefficient reflects the more efficient Li{sup +} pathway in the LFP powders through the aid of porous Cu network. - Highlights: • An efficient route was used to prepare Cu/LiFePO{sub 4} (LFP) hybrid as cathode material. • The Cu/LFP cathodes exhibit an improved performance as compared to fresh LFP one. • The microwave approach can deposit Cu network, fully covered the LFP powders. • The Cu network ensures LFP to get electrons, alleviating electrode polarization.

Microwave synthesis of copper network onto lithium iron phosphate cathode materials for improved electrochemical performance

International Nuclear Information System (INIS)

Hsieh, Chien-Te; Liu, Juan-Ru; Juang, Ruey-Shin; Lee, Cheng-En; Chen, Yu-Fu

2015-01-01

Herein reported is an efficient microwave-assisted (MA) approach for growing Cu network onto LiFePO 4 (LFP) powders as cathode materials for high-performance Li-ion batteries. The MA approach is capable of depositing highly-porous Cu network, fully covered the LFP powders. The electrochemical performance of Cu-coated LFP cathodes are well characterized by charge/discharge cycling and electrochemical impedance spectroscopy (EIS). The Cu network acts as the key role in improving the specific capacity, rate capability, electrode polarization, as compared to fresh LFP cathode without the Cu coating. The EIS incorporated with equivalent circuit reveals that the completed Cu network obviously suppresses the charge transfer resistance. This result can be attributed to the fact that the Cu network ensures the LFP crystals to get electron easily, alleviating the electrode polarization in view of one-dimensional Li + ion mobility in the olivine crystals. Based on the analysis of Randles plots, the relatively higher Li + diffusion coefficient reflects the more efficient Li + pathway in the LFP powders through the aid of porous Cu network. - Highlights: • An efficient route was used to prepare Cu/LiFePO 4 (LFP) hybrid as cathode material. • The Cu/LFP cathodes exhibit an improved performance as compared to fresh LFP one. • The microwave approach can deposit Cu network, fully covered the LFP powders. • The Cu network ensures LFP to get electrons, alleviating electrode polarization

Attentional Performance is Correlated with the Local Regional Efficiency of Intrinsic Brain Networks

Directory of Open Access Journals (Sweden)

Junhai eXu

2015-07-01

Full Text Available Attention is a crucial brain function for human beings. Using neuropsychological paradigms and task-based functional brain imaging, previous studies have indicated that widely distributed brain regions are engaged in three distinct attention subsystems: alerting, orienting and executive control (EC. Here, we explored the potential contribution of spontaneous brain activity to attention by examining whether resting-state activity could account for individual differences of the attentional performance in normal individuals. The resting-state functional images and behavioral data from attention network test (ANT task were collected in 59 healthy subjects. Graph analysis was conducted to obtain the characteristics of functional brain networks and linear regression analyses were used to explore their relationships with behavioral performances of the three attentional components. We found that there was no significant relationship between the attentional performance and the global measures, while the attentional performance was associated with specific local regional efficiency. These regions related to the scores of alerting, orienting and EC largely overlapped with the regions activated in previous task-related functional imaging studies, and were consistent with the intrinsic dorsal and ventral attention networks (DAN/VAN. In addition, the strong associations between the attentional performance and specific regional efficiency suggested that there was a possible relationship between the DAN/VAN and task performances in the ANT. We concluded that the intrinsic activity of the human brain could reflect the processing efficiency of the attention system. Our findings revealed a robust evidence for the functional significance of the efficiently organized intrinsic brain network for highly productive cognitions and the hypothesized role of the DAN/ VAN at rest.

Reducing Communication Overhead by Scheduling TCP Transfers on Mobile Devices using Wireless Network Performance Maps

DEFF Research Database (Denmark)

Højgaard-Hansen, Kim; Madsen, Tatiana Kozlova; Schwefel, Hans-Peter

2012-01-01

The performance of wireless communication networks has been shown to have a strong location dependence. Measuring the performance while having accurate location information available makes it possible to generate performance maps. In this paper we propose a framework for the generation and use...... of such performance maps. We demonstrate how the framework can be used to reduce the retransmissions and to better utilise network resources when performing TCP-based file downloads in vehicular M2M communication scenarios. The approach works on top of a standard TCP stack hence has to map identified transmission...

Distributed dynamic simulations of networked control and building performance applications

NARCIS (Netherlands)

Yahiaoui, Azzedine

2018-01-01

The use of computer-based automation and control systems for smart sustainable buildings, often so-called Automated Buildings (ABs), has become an effective way to automatically control, optimize, and supervise a wide range of building performance applications over a network while achieving the

Entrepreneurial networking: A blessing or a curse?: Differential effects for low, medium and high performing franchisees

OpenAIRE

Croonen, Evelien; Brand, Maryse; Leenders, R.T.A.J.

2018-01-01

Recent studies have called for a better understanding of the link between networking and entrepreneurial performance. We provide such understanding in three ways: by focusing on a specific entrepreneurial context (franchise systems), by developing a multi-faceted theoretical framework and by highlighting a contingency that may affect the networking-performance link. We combine knowledge and learning perspectives with a networking perspective to develop and test a multi-faceted framework on th...

The Performance Evaluation of an IEEE 802.11 Network Containing Misbehavior Nodes under Different Backoff Algorithms

Directory of Open Access Journals (Sweden)

Trong-Minh Hoang

2017-01-01

Full Text Available Security of any wireless network is always an important issue due to its serious impacts on network performance. Practically, the IEEE 802.11 medium access control can be violated by several native or smart attacks that result in downgrading network performance. In recent years, there are several studies using analytical model to analyze medium access control (MAC layer misbehavior issue to explore this problem but they have focused on binary exponential backoff only. Moreover, a practical condition such as the freezing backoff issue is not included in the previous models. Hence, this paper presents a novel analytical model of the IEEE 802.11 MAC to thoroughly understand impacts of misbehaving node on network throughput and delay parameters. Particularly, the model can express detailed backoff algorithms so that the evaluation of the network performance under some typical attacks through numerical simulation results would be easy.

High-Performance Neural Networks for Visual Object Classification

OpenAIRE

Cireşan, Dan C.; Meier, Ueli; Masci, Jonathan; Gambardella, Luca M.; Schmidhuber, Jürgen

2011-01-01

We present a fast, fully parameterizable GPU implementation of Convolutional Neural Network variants. Our feature extractors are neither carefully designed nor pre-wired, but rather learned in a supervised way. Our deep hierarchical architectures achieve the best published results on benchmarks for object classification (NORB, CIFAR10) and handwritten digit recognition (MNIST), with error rates of 2.53%, 19.51%, 0.35%, respectively. Deep nets trained by simple back-propagation perform better ...

Network DEA: an application to analysis of academic performance

Science.gov (United States)

Saniee Monfared, Mohammad Ali; Safi, Mahsa

2013-05-01

As governmental subsidies to universities are declining in recent years, sustaining excellence in academic performance and more efficient use of resources have become important issues for university stakeholders. To assess the academic performances and the utilization of the resources, two important issues need to be addressed, i.e., a capable methodology and a set of good performance indicators as we consider in this paper. In this paper, we propose a set of performance indicators to enable efficiency analysis of academic activities and apply a novel network DEA structure to account for subfunctional efficiencies such as teaching quality, research productivity, as well as the overall efficiency. We tested our approach on the efficiency analysis of academic colleges at Alzahra University in Iran.

78 FR 56875 - Tribal Mobility Fund Phase I Auction Rescheduled for December 19, 2013; Notice and Filing...

Science.gov (United States)

2013-09-16

... of comparing bids and measuring the performance of Tribal Mobility Fund Phase I support recipients..., EV-DO Rev A, UMTS/HSPA, HSPA+, WiMAX, and LTE. If the Mosaik data did not show such coverage, the...

Improving Network Performance with Affinity based Mobility Model in Opportunistic Network

OpenAIRE

Suvadip Batabyal; Parama Bhaumik

2012-01-01

Opportunistic network is a type of Delay Tolerant Network which is characterized by intermittent connectivity amongst the nodes and communication largely depends upon the mobility of the participating nodes. The network being highly dynamic, traditional MANET protocols cannot be applied and the nodes must adhere to store-carry-forward mechanism. Nodes do not have the information about the network topology, number of participating nodes and the location of the destination node. Hence, message ...

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.

Networks of dissipative systems compositional certification of stability, performance, and safety

CERN Document Server

Arcak, Murat; Packard, Andrew

2016-01-01

This book addresses a major problem for today’s large-scale networked systems: certification of the required stability and performance properties using analytical and computational models. On the basis of illustrative case studies, it demonstrates the applicability of theoretical methods to biological networks, vehicle fleets, and Internet congestion control. Rather than tackle the network as a whole —an approach that severely limits the ability of existing methods to cope with large numbers of physical components— the book develops a compositional approach that derives network-level guarantees from key structural properties of the components and their interactions. The foundational tool in this approach is the established dissipativity theory, which is reviewed in the first chapter and supplemented with modern computational techniques. The book blends this theory with the authors’ recent research efforts at a level that is accessible to graduate students and practising engineers familiar with only th...

Planar C-Band Antenna with Electronically Controllable Switched Beams

Directory of Open Access Journals (Sweden)

Mariano Barba

2009-01-01

Full Text Available The design, manufacturing, and measurements of a switchable-beam antenna at 3.5 GHz for WLL or Wimax base station antennas in planar technology are presented. This antenna performs a discrete beam scan of a 60∘ sector in azimuth and can be easily upgraded to 5 or more steps. The switching capabilities have been implemented by the inclusion of phase shifters based on PIN diodes in the feed network following a strategy that allows the reduction of the number of switches compared to a classic design. The measurements show that the design objectives have been achieved and encourage the application of the acquired experience in antennas for space applications, such as X-band SAR and Ku-band DBS.