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Access point selection in heterogeneous wireless networks using belief propagation

Science China(Information Sciences) 2014年第6期57卷 103-112页

作者： HOU RongHui LI JianDong SHENG Min YANG ChunGang State Key Lab of Integrated Service Networks Xidian University

The next generation wireless network will be composed by various heterogenous wireless access networks,such as cellular network,worldwide interoperability for microwave access(WiMAX),wireless local area network(WLAN),*** access networks cooperatively provide high-bandwidth connectivity with bandwidth *** paper proposes a utility-based access point selection scheme,which selects an accessible point for each user,such that the bandwidth requirement of each user is satisfied,and also the defined utility function is *** to the NP-complete nature of the problem,the existing proposals apply the greedy method to find a *** find that belief propagation is an efficient tool to solve this problem,and thus,we derive the same optimization objective in a new way,and then draw a factor graph representation which describes our combinatorial optimization ***,we develop the belief propagation algorithm,and show that our algorithm ***,we conduct numerical experiments to evaluate the convergency and accuracy of the belief propagation in load balancing problem.

关键词： heterogeneous wireless network QoS admission control belief propagation distributed algorithm

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Cross-layer optimization for performance trade-off in network code-based wireless multi-hop networks

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COMPUTER COMMUNICATIONS 2014年 52卷 89-101页

作者： Liu, Jain-Shing Lin, Chun-Hung Richard Providence Univ Dept Comp Sci & Informat Engn Taichung Taiwan Natl Sun Yat Sen Univ Dept Comp Sci & Engn Kaohsiung Taiwan

Maximizing network lifetime and optimizing aggregate system utility are important but usually conflict goals in wireless multi-hop networks. For the trade-off particularly for such networks equipped with the capability of network coding, we introduce a cross-layer optimization approach that can seamlessly accommodate routing, scheduling and stream control to simultaneously meet the diverse objectives with the aid of network utility maximization. Specifically, by taking into account both intra- and inter-session network coding and cross-layer formalization, the algorithms resulted are considered to be more general than those obtained from, e.g., poison-remedy based methods that focus on the methodology of network coding itself. In particular, along with a Markov Chain Monte Carlo method and a CSMA approximation, these algorithnis can dynamically approach the optimal solution while solving the scheduling subproblem involved, which is NP-hard in general, in a distributed manner. Finally, we present numerical results for the insight that can be gained from the cross-layer optimization and show that this work is capable on achieving an optimal trade-off between the lifetime and utility. (c) 2014 Elsevier B.V. All rights reserved.

关键词： Cross-layer optimization distributed algorithm Network coding Lifetime-utility tradeoff Markov approximation

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Cross-layer resource allocation in wireless multi-hop networks with outdated channel state information

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Journal of Zhejiang University-Science C(Computers and Electronics) 2014年第5期15卷 337-350页

作者： Wei FENG Sui-li FENG Yue-hua DING Xin HUANG School of Electronic and Information Engineering South China University of Technology School of Physics and Telecommunication Engineering South China Normal University

The cross-layer resource allocation problem in wireless multi-hop networks(WMHNs)has been extensively studied in the past few *** of these studies assume that every node has the perfect channel state information(CSI)of other *** practical settings,however,the networks are generally dynamic and CSI usually becomes outdated when it is used,due to the time-variant channel and feedback *** deal with this issue,we study the cross-layer resource allocation problem in dynamic WMHNs with outdated CSI under channel conditions where there is correlation between the outdated CSI and current *** major contributions are made in this work:(1)a closed-form expression of conditional average capacity is derived under the signal-to-interferenceplus-noise ratio(SINR)model;(2)a joint optimization problem of congestion control,power control,and channel allocation in the context of outdated CSI is formulated and solved in both centralized and distributed *** results show that the network utility can be improved significantly using our proposed algorithm.

关键词： Wireless multi-hop networks Outdated channel state information Cross-layer resource allocation distributed algorithm

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Xheal: a localized self-healing algorithm using expanders

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distributed COMPUTING 2014年第1期27卷 39-54页

作者： Pandurangan, Gopal Trehan, Amitabh Nanyang Technol Univ Div Math Sci Singapore 637371 Singapore Brown Univ Dept Comp Sci Providence RI 02912 USA Technion Israel Inst Technol Fac Ind Engn & Management IL-32000 Haifa Israel

We consider the problem of self-healing in reconfigurable networks e.g., peer-to-peer and wireless mesh networks. For such networks under repeated attack by an omniscient adversary, we propose a fully distributed algorithm, Xheal, that maintains good expansion and spectral properties of the network, while keeping the network connected. Moreover, Xheal does this while allowing only low stretch and degree increase per node. The algorithm heals global properties like expansion and stretch while only doing local changes and using only local information. We also provide bounds on the second smallest eigenvalue of the Laplacian which captures key properties such as mixing time, conductance, congestion in routing etc. Xheal has low amortized latency and bandwidth requirements. Our work improves over the self-healing algorithms Forgiving tree [PODC 2008] and Forgiving graph [PODC 2009] in that we are able to give guarantees on degree and stretch, while at the same time preserving the expansion and spectral properties of the network.

关键词： Self-healing Reconfigurable networks Peer-to-peer Local versus global Expansion Spectral properties distributed algorithm Randomized algorithm

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Joint Beamforming and Power Splitting for MISO Interference Channel With SWIPT: An SOCP Relaxation and Decentralized algorithm

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2014年第23期62卷 6194-6208页

作者： Shi, Qingjiang Xu, Weiqiang Chang, Tsung-Hui Wang, Yongchao Song, Enbing Zhejiang Sci Tech Univ Sch Informat Sci & Technol Hangzhou 310018 Zhejiang Peoples R China Xidian Univ State Key Lab Integrated Serv Networks Xian 710071 Peoples R China Natl Taiwan Univ Sci & Technol Dept Elect & Comp Engn Taipei 10607 Taiwan Sichuan Univ Coll Math Chengdu 610064 Sichuan Peoples R China

This paper considers a power splitting-based MISO interference channel for simultaneous wireless information and power transfer (SWIPT), where each single antenna receiver splits the received signal into two streams of different power for decoding information and harvesting energy separately. We aim to minimize the total transmission power by joint beamforming and power splitting (JBPS) under both the signal-to-interference-plus-noise ratio (SINR) constraints and energy harvesting (EH) constraints. The JBPS problem is nonconvex and has not yet been well addressed in the literature. Moreover, decentralized algorithm design for JBPS based on local channel state information (CSI) and limited information exchange remains open. In this paper, we first propose a novel relaxation method named second-order cone programming (SOCP) relaxation to address the JBPS problem. We formulate the relaxed problem as an SOCP and present two sufficient conditions under which the SOCP relaxation is tight. For the case when the SOCP solution is not necessarily optimal to the JBPS problem, a closed-form feasible-solution-recovery method is provided. Then, we develop a distributed algorithm for the JBPS problem based on primal-decomposition (PD) method. The PD-based distributed algorithm consists of a master problem and a set of subproblems. The former is solved by using subgradient method while the latter are solved using coordinate descent method. Finally, numerical results validates the efficiency of the proposed algorithms.

关键词： Beamforming distributed algorithm dynamic power splitting MISO interference channel simultaneous wireless information and power transfer SOCP

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Optimal Energy Scheduling for Residential Smart Grid with Centralized Renewable Energy Source

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IEEE SYSTEMS JOURNAL 2014年第2期8卷 562-576页

作者： Wu, Yuan Lau, Vincent K. N. Tsang, Danny H. K. Qian, Li Ping Meng, Limin Hong Kong Univ Sci & Technol Hong Kong Hong Kong Peoples R China Zhejiang Univ Technol Coll Informat Engn Hangzhou Zhejiang Peoples R China Nanjing Univ State Key Lab Novel Software Technol Nanjing Jiangsu Peoples R China Hong Kong Univ Sci & Technol Dept Elect & Comp Engn Hong Kong Hong Kong Peoples R China Zhejiang Univ Technol Coll Comp Sci & Technol Hangzhou Zhejiang Peoples R China

Future smart grids will be featured by flexible supply-demand management and great penetration of renewable energy to enable efficient and economical grid operations. While the renewable energy offers a cheaper and cleaner energy supply, it introduces supply uncertainty due to the volatility of renewable source. It is therefore of practical importance to investigate the optimal exploitation of renewable energy based on the supply-demand framework of future smart grids, where the energy-providers (or the energy-users) adaptively adjust their energy-provisioning (or energy-demands) according to some system state information that takes into account the volatility of renewable energy. Specifically, we consider cost-efficient energy scheduling for residential smart grids equipped with a centralized renewable energy source. Our scheduling problem aims at: 1) quantifying the optimal utilization of renewable energy that achieves the tradeoff between the system-wide benefit from exploiting the renewable energy and the associated cost due to its volatility;and 2) evaluating how the volatility of renewable energy influences its optimal exploitation. We also propose computationally efficient and distributed algorithms to determine the optimal exploitation of renewable energy as well as the associated energy scheduling decisions.

关键词： distributed algorithm monotonic optimization stochastic dominance supply uncertainty supply-demand response management volatility of renewable energy

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Managing performance and power consumption tradeoff for multiple heterogeneous servers in cloud computing

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CLUSTER COMPUTING-THE JOURNAL OF NETWORKS SOFTWARE TOOLS AND APPLICATIONS 2014年第3期17卷 943-955页

作者： Tian, Yuan Lin, Chuang Li, Keqin Tsinghua Univ Comp Sci & Technol Dept Beijing 100084 Peoples R China SUNY Coll New Paltz Dept Comp Sci New Paltz NY 12561 USA

There are typically multiple heterogeneous servers providing various services in cloud computing. High power consumption of these servers increases the cost of running a data center. Thus, there is a problem of reducing the power cost with tolerable performance degradation. In this paper, we optimize the performance and power consumption tradeoff for multiple heterogeneous servers. We consider the following problems: (1) optimal job scheduling with fixed service rates;(2) joint optimal service speed scaling and job scheduling. For problem (1), we present the Karush-Kuhn-Tucker (KKT) conditions and provide a closed-form solution. For problem (2), both continuous speed scaling and discrete speed scaling are considered. In discrete speed scaling, the feasible service rates are discrete and bounded. We formulate the problem as an MINLP problem and propose a distributed algorithm by online value iteration, which has lower complexity than a centralized algorithm. Our approach provides an analytical way to manage the tradeoff between performance and power consumption. The simulation results show the gain of using speed scaling, and also prove the effectiveness and efficiency of the proposed algorithms.

关键词： Cloud computing Convex optimization distributed algorithm Heterogeneous server Performance and power tradeoff Power consumption Response time

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Non-cooperative games with minmax objectives

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COMPUTATIONAL OPTIMIZATION AND APPLICATIONS 2014年第1-2期59卷 85-112页

作者： Facchinei, Francisco Pang, Jong-Shi Scutari, Gesualdo Univ Roma La Sapienza Dept Comp Control & Management Engn Antonio Ruber I-00185 Rome Italy Univ So Calif Deptartment Ind & Syst Engn Los Angeles CA USA SUNY Buffalo Dept Elect Engn Buffalo NY 14260 USA

We consider noncooperative games where each player minimizes the sum of a smooth function, which depends on the player, and of a possibly nonsmooth function that is the same for all players. For this class of games we consider two approaches: one based on an augmented game that is applicable only to a minmax game and another one derived by a smoothing procedure that is applicable more broadly. In both cases, centralized and, most importantly, distributed algorithms for the computation of Nash equilibria can be derived.

关键词： Nash equilibrium problem Nondifferentiable objective function distributed algorithm Smoothing

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Segmentation of colon tissue sample images using multiple graphics accelerators

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COMPUTERS IN BIOLOGY AND MEDICINE 2014年 51卷 93-103页

作者： Szenasi, Sandor Obuda Univ John von Neumann Fac Informat H-1034 Budapest Hungary

Nowadays, processing medical images is increasingly done through using digital imagery and custom software solutions. The distributed algorithm presented in this paper is used to detect special tissue parts, the nuclei on haematoxylin and eosin stained colon tissue sample images. The main aim of this work is the development of a new data-parallel region growing algorithm that can be implemented even in an environment using multiple video accelerators. This new method has three levels of parallelism: (a) the parallel region growing itself, (b) starting more region growing in the device, and (c) using more than one accelerator. We use the split-and-merge technique based on our already existing data-parallel cell nuclei segmentation algorithm extended with a fast, backtracking-based, non-overlapping cell filter method. This extension does not cause significant degradation of the accuracy;the results are practically the same as those of the original sequential region growing method. However, as expected, using more devices usually means that less time is needed to process the tissue image;in the case of the configuration of one central processing unit and two graphics cards, the average speed-up is about 4-6 x. The implemented algorithm has the additional advantage of efficiently processing very large images with high memory requirements. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Medical image segmentation Cell nuclei detection Data parallel algorithm distributed algorithm GPGPU CUDA

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A strengthened analysis of a local algorithm for the minimum dominating set problem in planar graphs

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INFORMATION PROCESSING LETTERS 2014年第3期114卷 94-98页

作者： Wawrzyniak, Wojciech Adam Mickiewicz Univ Fac Math & Comp Sci Poznan Poland

In recent years growing interest in local distributed algorithms has widely been observed. This results from their high resistance to errors and damage, as well as from their good performance, which is independent of the size of the network. A local deterministic distributed algorithm finding an approximation of a Minimum Dominating Set in planar graphs has been presented by Lenzen et al., and they proved that the algorithm returns a 130-approximation of the Minimum Dominating Set. In this article we will show that the algorithm is two times more effective than was previously assumed, and we prove that the algorithm by Lenzen et al. outputs a 52-approximation to a Minimum Dominating Set. Therefore the gap between the lower bound and the approximation ratio of the best yet local deterministic distributed algorithm is reduced by half. (C) 2013 Published by Elsevier B.V.

关键词： Approximation algorithms distributed algorithm Local algorithm Dominating set Planar graph

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