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IEEE Conference on Wireless communications and Networking

作者： Tianyu Wang Lingyang Song Zhu Han Walid Saad State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electrical Engineering and Computer Science Peking University China Electrical and Computer Engineering Department University of Houston Houston TX USA Electrical and Computer Engineering Department University of Miami Coral Gables FL USA

ISBN: (纸本)9781467359382

Collaborative spectrum sensing (CSS) has been shown to be able to highly improve the performance of spectrum sensing in cognitive radio networks. However, most existing works focused on either centralized approaches that rely on a global fusion center, thus requiring significant overhead, or on distributed approaches that rely on disjoint coalitions of secondary users (SUs) in which an SU can only cooperate with a single, selected coalition, hence limiting the performance gains of CSS. In this paper, a novel, coalition-based approach to CSS is proposed in which an SU can share its sensing results with more than one coalition. The problem is formulated using a novel class of cooperative games, known as overlapping coalitional games, which enables the SUs to decide, in a distributed manner, on the number of coalitions in which they wish to cooperate, depending on the associated benefit and cost tradeoffs. To solve this game, a novel, distributed algorithm is proposed using which the SUs can self-organize into a stable overlapping coalitional structure. Simulation results show that our proposed algorithm significantly improves the performance in terms of both the average probability of misdetection and the convergence time, relative to the noncooperative case and the state-of-art cooperative CSS with non-overlapping coalitions.

关键词： Sensors Cascading style sheets Games Partitioning algorithms Collaboration Fading Educational institutions

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Dynamic bandwidth allocation& guarantee for virtualized networks in cloud

Dynamic bandwidth allocation& guarantee for virtualized netw...

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International Conference on Information, communications and Signal Processing

作者： Xuan Luo Pengfei Zhang Tong Ye Yaohui Jin Jianping Wang Network and Information Center Shanghai Jiaotong University State Key Laboratory of Advanced Optical Communication Systems & Networks Shanghai Jiaotong University Department of Computer Science City University of Hong Kong

ISBN: (纸本)9781479904327

Among all SLAs(Service Level Agreements) about network resources in the cloud, a critical problem would be achieving bandwidth guarantee under all communication environment (e.g., when misbehaved VMs exist) while keeping acceptable bandwidth utility and system scalability. In this paper, we present an architecture of dynamic bandwidth allocation and guarantee on resource fairness, to provide network performance isolation and protocol independent bandwidth guarantees. In this paper, we first discuss the business model of bandwidth guarantee for Infrastructure-as-a-Service (IaaS) cloud, and a bandwidth allocation algorithm based on redefined fairness model is proposed and realized under the novel architecture, and finally experiment shows satisfying results under various communication scenarios.

关键词： Bandwidth Switches Protocols Integrated circuits

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Lecture Notes in computer science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics): Preface

Lecture Notes in Computer Science (including subseries Lectu...

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Lecture Notes in computer science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2013年 8166 LNCS卷 V-VI页

作者： Gorbenko, Anatoliy Romanovsky, Alexander Kharchenko, Vyacheslav National Aerospace University Department of Computer Systems and Networks 17 Chkalov Street 61070 Kharkiv Ukraine Newcastle University School of Computing Science Claremont Tower Newcastle upon Tyne NE1 7RU United Kingdom

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Superradiant Laser with Ultra-Narrow Linewidth Based on 40Ca

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Chinese Physics Letters 2012年第7期29卷 84-86页

作者： WANG Yan-Fei CHEN Jing-Biao State Key Laboratory of Advanced Optical Communication Systems and Networks Institute of Quantum ElectronicsSchool of Electronics Engineering&Computer SciencePeking UniversityBeijing 100871

An experiment setup for narrow linewidth superradiant laser based on the mechanism of an active optical clock is proposed with optical lattice trapped 40 *** obtain the threshold pumping rate analytically and deduce the linewidth of the superradiant laser in a bad cavity *** proposed laser has an extremely narrow linewidth at millihertz level and a power level of order 10^(-9) W.

关键词： pumping narrow regime

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To crash or not to crash: Estimating its likelihood and potentials of beacon-based IVC systems

To crash or not to crash: Estimating its likelihood and pote...

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2012 IEEE Vehicular Networking Conference, VNC 2012

作者： Joerer, Stefan Segata, Michele Bloessl, Bastian Cigno, Renato Lo Sommer, Christoph Dressler, Falko Computer and Communication Systems Institute of Computer Science University of Innsbruck Austria Systems and Networks Dept. of Information Engineering and Computer Science University of Trento Italy

ISBN: (纸本)9781467349963

Is it possible to estimate some 'safety' metric to assess the effectiveness of Intelligent Transportation systems? In particular, we are interested in using Inter-Vehicle communication (IVC) beaconing for increasing drivers' safety at intersections. In the last couple of years, the vehicular networking community reported in several studies that simple network metrics are not sufficient to evaluate safety enhancing protocols and applications. We present a classification scheme that allows the quantification of such improvements by determining how many potential crashes happen or can be avoided by a specific IVC approach. Using a modified road traffic simulator that allowed selected vehicles to disregard traffic rules, we investigated the impact of safety messaging between cars approaching an intersection. We show that in suburban environments simple beaconing is not as effective as anticipated. Yet, simple one-hop-relaying, e.g., by vehicles parked close to an intersection, can improve drivers' safety substantially. Since the key purpose of IVC is safety, the paper closes the loop in the evaluation of the effectiveness of vehicular networks as defined today. © 2012 IEEE.

关键词： Vehicles

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How Shadowing Hurts Vehicular communications and How Dynamic Beaconing Can Help

How Shadowing Hurts Vehicular Communications and How Dynamic...

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IEEE INFOCOM Conference

作者： Christoph Sommer Stefan Joerer Michele Segata Ozan Tonguz Renato Lo Cigno Falko Dressler Computer and Communication Systems Institute of Computer Science University of Innsbruck Austria Electrical and Computer Engineering Dept. Carnegie Mellon University Pittsburgh PA Systems and Networks Dept. of Information Engineering and Computer Science University of Trento Italy

ISBN: (纸本)9781467359443

We study the effect of radio signal shadowing dynamics, caused by vehicles and by buildings, on the performance of beaconing protocols in Inter-Vehicular communication (IVC). Recent research indicates that beaconing, i.e., one hop message broadcast, shows excellent characteristics and can outperform other communication approaches for both safety and efficiency applications, which require low latency and wide area information dissemination, respectively. We show how shadowing dynamics of moving obstacles hurt IVC, reducing the performance of beaconing protocols. At the same time, shadowing also limits the risk of overloading the wireless channel. To the best of our knowledge, this is the first study identifying the problems and resulting possibilities of such dynamic radio shadowing. We demonstrate how these challenges and opportunities can be taken into account and outline a novel approach to dynamic beaconing. It provides low-latency communication (i.e., very short beaconing intervals), while ensuring not to overload the wireless channel. The presented simulation results substantiate our theoretical considerations.

关键词： beaconing Simulation results Shadowing (Histology) Moving obstacles communication Research

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Energy-Efficient LDPC Layered Decoder

Energy-Efficient LDPC Layered Decoder

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2013 IEEE 4th International Conference on Electronics Information and Emergency communication

作者： Jianjun Zhang Da Wang Ye Jin State Key Laboratory of Advanced Optical Communication Systems & Networks School of Electronics Engineering and Computer Science Peking University

ISBN: (纸本)9781467349345

It is very important to reduce the energy consumption of low-density parity-check (LDPC) decoders, especially for the intelligent and mobile terminals in green communications. This paper presents a novel energy-efficient layered decoder (EELD) to save the power consumption of quasi-cyclic LDPC (QC-LDPC) decoders based on the layered belief propagation (LBP) algorithm. The EELD forces a check-node process into asleep, when all the reliabilities of its neighboring variable nodes exceed the lazy threshold. The EELD also adopts the lower limit of the beliefs, rather than all the beliefs, of the neighboring variable nodes to compare with the lazy threshold in order to decide the state of check-node process. The EELD can skip the useless check-node processes to save energy consumption with slight additional complexity. Simulation results show that the EELD can improve the power efficiencies of the decoders by up to 28% for WiMAX codes without loss of error performances.

关键词： Low-density parity-check codes, energy efficient, layered belief propagation, WiMAX.

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Conversational quality as a function of delay and interactivity

Conversational quality as a function of delay and interactiv...

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2012 20th International Conference on Software, Telecommunications and computer networks, SoftCOM 2012

作者： Issing, Jochen Färber, Nikolaus Dept. Computer Science 7 Computer Networks and Communication Systems Friedrich-Alexander-University Erlangen Germany Multimedia Transport Group Fraunhofer IIS Erlangen Germany

ISBN: (纸本)9789532900347

The impact of mouth-to-ear delay on Conversational Quality (CQ) has been subject to manyfold research in the field of telecommunications. However, its dependency on Conversational Interactivity (CI) has not been studied explicitly in a quantitative way. To investigate the impact of both delay and CI, we conducted 48 tests with 96 different participants and controlled the interactivity through different tasks, namely natural conversation (flight), proof reading of text (text), and random number verification (rnv). The control of interactivity is proven to be effective and remains stable for delays from 100 ms to 800 ms. The Speaker Alternation Rate (SAR) is used as the metric for interactivity. It is shown to have a significant impact on CQ after 200ms delay and the effect does not alleviate until 800 ms. The hypothesis is proven using both graphical analysis and statistical evaluation based on a linear model and Analysis of Variance (ANOVA). © 2012 University of Split.

关键词： Analysis of variance (ANOVA)

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Metamaterial absorbers realized in an X-band rectangular waveguide

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Chinese Physics B 2012年第11期21卷 474-478页

作者：黄勇军文光俊李建钟靖平王平孙元华 O.Gordon 朱卫仁 Key Laboratory of Broadband Optical Fiber Transmission&Communication Networks School of Communication and Information EngineeringUniversity of Electronic Science and Technology of China Advanced Computing and Simulation Laboratory(AχL) Department of Electrical and Computer Systems EngineeringMonash University

In this paper, we demonstrate six types of metamaterial absorbers （MMAs） by measuring their absorptivities in an X-band （8 12 GHz） rectangular waveguide. Some of the MMAs have been demonstrated previously by using the free space measurement method, and the others are proposed firstly in this paper. The measured results show that all of the six MMAs exhibit high absorptivities above 98%, which have similar absorbing characteristics to those measured in the free space. The numerically obtained surface current densities for each MMA show that the absorbing mechanism is the same as that under the free space conditions. Such a demonstration method is superior to the conventional free space measurement method due to the small-scale test samples required, the simple measure device, and its low cost. Most importantly, the proposed method opens a way to enable MMAs to be used in microwave applications such as matched terminations.

关键词： metamaterial absorber electric resonator rectangular waveguide

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Autonomous community construction and coordination technology to achieve real-time transmission in multiple emergencies' situation

Autonomous community construction and coordination technolog...

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作者： Wei, Fan Haque, M. Emdadul Lu, Xiaodong Mori, Kinji Electronic Navigation Research Institute 7-42-23 Jindaiji-higashimachi Chofu Tokyo 182-0012 Japan School of Computer Science Xi'An Shiyou University No. 18 Dianzi 2nd Road Xi'an 710065 China Department of Information and Communication Engineering University of Rajshahi Rajshahi 6205 Bangladesh Green Computing Systems Research Organization Waseda University Waseda Bld. 40-305 27 Waseda Shinjuku Tokyo 162-0042 Japan

Wireless Sensor Network (WSN) is used in Emergency Management System (EMS). If emergency situation happens, real-timely transmitting emergency information in dynamically changing environment should be assured. But this requirement could not be satisfied by conventional approaches which are based on static situation and centralized management. In this paper, to satisfy this requirement, autonomous community construction technology is proposed for single emergency. Emergency information could be transmitted in community and protected from interference of other information's transmission. Moreover, autonomous coordination technology is proposed for multiple emergencies' information's transmission. Via this technology, each emergency could have its individual route to transmit emergency information. Each emergency information's transmission will not influence with each other. Evaluation results are provided to demonstrate the improvement. © 2013 Springer science+Business Media New York.

关键词： Wireless sensor networks

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