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A distributed TRANSPORTATION SIMPLEX APPLIED TO A CONTENT DISTRIBUTION NETWORK PROBLEM

RAIRO-OPERATIONS RESEARCH 2014年第2期48卷 189-210页

作者： Coutinho, Rafaelli de C. Drummond, Lucia M. A. Frota, Yuri Univ Fed Fluminense Inst Comp BR-24220000 Niteroi RJ Brazil

A Content Distribution Network (CDN) can be defined as an overlay system that replicates copies of contents at multiple points of a network, close to the final users, with the objective of improving data access. CDN technology is widely used for the distribution of large-sized contents, like in video streaming. In this paper we address the problem of finding the best server for each customer request in CDNs, in order to minimize the overall cost. We consider the problem as a transportation problem and a distributed algorithm is proposed to solve it. The algorithm is composed of two independent phases: a distributed heuristic finds an initial solution that may be later improved by a distributed transportation simplex algorithm. It is compared with the sequential version of the transportation simplex and with an auction-based distributed algorithm. Computational experiments carried out on a set of instances adapted from the literature revealed that our distributed approach has a performance similar or better to its sequential counterpart, in spite of not requiring global information about the contents requests. Moreover, the results also showed that the new method outperforms the based-auction distributed algorithm.

关键词： CDN transportation simplex algorithm distributed algorithm

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distributed Deployment algorithms for Efficient Coverage in a Network of Mobile Sensors With Nonidentical Sensing Capabilities

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2014年第8期63卷 3998-4016页

作者： Mahboubi, Hamid Moezzi, Kaveh Aghdam, Amir G. Sayrafian-Pour, Kamran McGill Univ Dept Elect & Comp Engn Montreal PQ H3A 0E9 Canada AKKA Tech Montreal PQ H3B 1X9 Canada Concordia Univ Dept Elect & Comp Engn Montreal PQ H3G 1M8 Canada NIST Informat Technol Lab Gaithersburg MD 20899 USA Voyan Technol Santa Clara CA USA Univ Toronto Syst Control Grp Toronto ON M5S 1A1 Canada Concordia Univ Montreal PQ H3G 1M8 Canada Zagros Networks Inc Rockville MD USA Univ Maryland College Pk MD USA

In this paper, efficient deployment algorithms are proposed for a mobile sensor network to improve the coverage area. The proposed algorithms find the target position of each sensor iteratively, based on the existing coverage holes in the network. The multiplicatively weighted Voronoi (MW-Voronoi) diagram is used to discover the coverage holes corresponding to different sensors with different sensing ranges. Three sensor deployment algorithms are provided, which tend to either move sensors out of densely packed areas or place them in proper positions with respect to the boundaries of the MW-Voronoi regions. Under the proposed procedures, the sensors move in such a way that the coverage holes in the target field are reduced. Simulations confirm the effectiveness of the deployment algorithms proposed in this paper.

关键词： Coverage distributed algorithm mobile sensor networks

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distributed Lifetime and Data Rate Optimization with Dynamic Approximation in Wireless Networks

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WIRELESS PERSONAL COMMUNICATIONS 2014年第1期75卷 179-194页

作者： Liu, Jain-Shing Providence Univ Dept Comp Sci & Informat Engn Taichung Taiwan

In this paper, we study the problem of jointly maximizing network lifetime and data rate in wireless networks. For this problem, we introduce a general network utility maximization (NUM) cross-layer formulation that accommodates routing, scheduling and stream control from different layers of network with relevant constraints. In particular, based on both Lagrangian approach and Markov Chain Monte Carlo method, we extend our programming model to distributed algorithms that can dynamically approximate the optimal solution to this problem. Finally, we present computational results for the insight that can be gained from the cross-layer optimization and the distributed algorithms.

关键词： Cross-layer design distributed algorithm CSMA approximation Performance optimization

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distributed User Association and Femtocell Allocation in Heterogeneous Wireless Networks

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IEEE TRANSACTIONS ON COMMUNICATIONS 2014年第8期62卷 3027-3043页

作者： Bayat, Siavash Louie, Raymond H. Y. Han, Zhu Vucetic, Branka Li, Yonghui Sharif Univ Technol Elect Res Inst Tehran 14588 Iran Hong Kong Univ Sci & Technol Dept Elect & Comp Engn Hong Kong Hong Kong Peoples R China Univ Houston Dept Elect & Comp Engn Houston TX 77204 USA Univ Sydney Sch Elect & Informat Engn Ctr Excellence Telecommun Sydney NSW 2006 Australia

Deployment of low-power low-cost small access points such as femtocell access points (FAPs) constitute an attractive solution for improving the existing macrocell access points' (MAPs) capacity, reliability, and coverage. However, FAP deployment faces challenging problems such as interference management and the lack of flexible frameworks for deploying the FAPs by the service providers (SPs). In this paper, we propose a novel solution that jointly associates the user equipment (UE) to the APs, and allocates the FAPs to the SPs such that the the total satisfaction of the UEs in an uplink OFDMA network is maximized. We model the competitive behaviors among the UEs, FAPs, and SPs as a dynamic matching game and we propose distributed algorithms to find the optimal UE association and FAP allocations. We show analytically that the matching algorithms converge to the optimal and stable outcomes after a small number of iterations. Simulations and analytical results show the proposed mechanism is arbitrarily close to the global optimal solution by setting a design parameter (step number) but has significantly reduced overhead and complexity over the centralized algorithm.

关键词： Femtocell allocation user association open access resource allocation distributed algorithm

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distributed Compressed Sensing for Static and Time-Varying Networks

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2014年第19期62卷 4931-4946页

作者： Patterson, Stacy Eldar, Yonina C. Keidar, Idit Rensselaer Polytech Inst Dept Comp Sci Troy NY 12180 USA Technion Israel Inst Technol Dept Elect Engn IL-32000 Haifa Israel

We consider the problem of in-network compressed sensing from distributed measurements. Every agent has a set of measurements of a signal, and the objective is for the agents to recover from their collective measurements using only communication with neighbors in the network. Our distributed approach to this problem is based on the centralized Iterative Hard Thresholding algorithm (IHT). We first present a distributed IHT algorithm for static networks that leverages standard tools from distributed computing to execute in-network computations with minimized bandwidth consumption. Next, we address distributed signal recovery in networks with time-varying topologies. The network dynamics necessarily introduce inaccuracies to our in-network computations. To accommodate these inaccuracies, we show how centralized IHT can be extended to include inexact computations while still providing the same recovery guarantees as the original IHT algorithm. We then leverage these new theoretical results to develop a distributed version of IHT for time-varying networks. Evaluations show that our distributed algorithms for both static and time-varying networks outperform previously proposed solutions in time and bandwidth by several orders of magnitude.

关键词： Compressed sensing distributed algorithm distributed consensus iterative hard thresholding sparse recovery

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Game-Theoretic Approach to Self-Stabilizing distributed Formation of Minimal Multi-Dominating Sets

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IEEE TRANSACTIONS ON PARALLEL AND distributed SYSTEMS 2014年第12期25卷 3201-3210页

作者： Yen, Li-Hsing Chen, Zong-Long Natl Univ Kaohsiung Dept Comp Sci & Informat Engn Kaohsiung 811 Taiwan

Dominating set is a subset of nodes called dominators in a graph such that every non-dominator nodes (called dominatee) is adjacent to at least one dominator. This paper considers a more general multi-dominating problem where each node i, dominator or dominatee, is required to have at least k(i) neighboring dominators, and different node can have different ki value. We first propose a game design toward this problem. This game is self-stabilizing (i.e., it always ends up with a legitimate state regardless of its initial configuration). The obtained result is guaranteed minimal (i.e., it contains no proper subset that is also a multi-dominating set) and Pareto optimal (we cannot increase the payoff of some player without sacrificing the payoff of any other). We then point out challenges when turning the design into a distributed algorithm using guarded commands. We present an algorithm that is proved weakly stabilizing. Simulation results show that the proposed game and algorithm produce smaller dominating sets, k-dominating sets, and multi-dominating sets in various network topologies when compared with prior approaches.

关键词： Dominating set self-stabilization distributed algorithm game theory

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Optimal distributed Malware Defense in Mobile Networks with Heterogeneous Devices

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IEEE TRANSACTIONS ON MOBILE COMPUTING 2014年第2期13卷 377-391页

作者： Li, Yong Hui, Pan Jin, Depeng Su, Li Zeng, Lieguang Tsinghua Univ Dept Elect Engn TNLIST State Key Lab Microwave & Digital Commun Beijing 100084 Peoples R China Hong Kong Univ Sci & Technol Dept Comp Sci & Engn Hong Kong Hong Kong Peoples R China Aalto Univ Espoo Finland

As malware attacks become more frequently in mobile networks, deploying an efficient defense system to protect against infection and to help the infected nodes to recover is important to prevent serious spreading and outbreaks. The technical challenges are that mobile devices are heterogeneous in terms of operating systems, the malware infects the targeted system in any opportunistic fashion via local and global connectivity, while the to-be-deployed defense system on the other hand would be usually resource limited. In this paper, we investigate the problem of how to optimally distribute the content-based signatures of malware, which helps to detect the corresponding malware and disable further propagation, to minimize the number of infected nodes. We model the defense system with realistic assumptions addressing all the above challenges that have not been addressed in previous analytical work. Based on the framework of optimizing the system welfare utility, which is the weighted summation of individual utility depending on the final number of infected nodes through the signature allocation, we propose an encounter-based distributed algorithm based on Metropolis sampler. Through theoretical analysis and simulations with both synthetic and realistic mobility traces, we show that the distributed algorithm achieves the optimal solution, and performs efficiently in realistic environments.

关键词： Security threat mobile malware distributed algorithm heterogeneous mobile networks

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distributed Channel Allocation Protocols for Wireless Sensor Networks

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IEEE TRANSACTIONS ON PARALLEL AND distributed SYSTEMS 2014年第9期25卷 2264-2274页

作者： Saifullah, Abusayeed Xu, You Lu, Chenyang Chen, Yixin Washington Univ Dept Comp Sci & Engn St Louis MO 63130 USA

Interference between concurrent transmissions can cause severe performance degradation in wireless sensor networks (WSNs). While multiple channels available in WSN technology such as IEEE 802.15.4 can be exploited to mitigate interference, channel allocation can have a significant impact on the performance of multi-channel communication. This paper proposes a set of distributed protocols for channel allocation in WSNs with theoretical bounds. We first consider the problem of minimizing the number of channels needed to remove interference in a WSN, and propose both receiver-based and link-based distributed channel allocation protocols. Then, for WSNs with an insufficient number of channels, we formulate a fair channel allocation problem whose objective is to minimize the maximum interference (MinMax) experienced by any transmission link in the network. We prove that MinMax channel allocation is NP-hard, and propose a distributed link-based MinMax channel allocation protocol. Finally, we propose a distributed protocol for link scheduling based on MinMax channel allocation that creates a conflict-free schedule for transmissions. The proposed decentralized protocols are efficient, scalable, and adaptive to channel condition and network dynamics. Simulations based on the topologies and data traces collected from a WSN testbed of 74 TelosB motes have shown that our channel allocation protocols significantly outperform a state-of-the-art channel allocation protocol.

关键词： Wireless sensor network multi-channel channel allocation distributed algorithm

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distributed PROXIMAL-GRADIENT METHOD FOR CONVEX OPTIMIZATION WITH INEQUALITY CONSTRAINTS

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ANZIAM JOURNAL 2014年第2期56卷 160-178页

作者： Li, Jueyou Wu, Changzhi Wu, Zhiyou Long, Qiang Wang, Xiangyu Chongqing Normal Univ Sch Math Chongqing 400047 Peoples R China Federat Univ Australia Sch SITE Ballarat Vic 3353 Australia Curtin Univ Sch Built Environm Australasian Joint Res Ctr Bldg Informat Modellin Bentley WA 6102 Australia Southwest Univ Sci & Technol Sch Sci Chengdu 621010 Sichuan Peoples R China Kyung Hee Univ Dept Housing & Interior Design Seoul South Korea

We consider a distributed optimization problem over a multi-agent network, in which the sum of several local convex objective functions is minimized subject to global convex inequality constraints. We first transform the constrained optimization problem to an unconstrained one, using the exact penalty function method. Our transformed problem has a smaller number of variables and a simpler structure than the existing distributed primal-dual subgradient methods for constrained distributed optimization problems. Using the special structure of this problem, we then propose a distributed proximal-gradient algorithm over a time-changing connectivity network, and establish a convergence rate depending on the number of iterations, the network topology and the number of agents. Although the transformed problem is nonsmooth by nature, our method can still achieve a convergence rate, O(1/k), after k iterations, which is faster than the rate, O(1/root k), of existing distributed subgradient-based methods. Simulation experiments on a distributed state estimation problem illustrate the excellent performance of our proposed method.

关键词： distributed algorithm proximal-gradient method exact penalty function method convex optimization

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An energy and memory-efficient distributed self-reconfiguration for modular sensor/robot networks

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JOURNAL OF SUPERCOMPUTING 2014年第2期69卷 908-929页

作者： Lakhlef, Hicham Mabed, Hakim Bourgeois, Julien UFC FEMTO ST UMR CNRS 6174 Montbeliard France

Self-reconfiguration for mobile microrobots currently needs a positioning system and a map of the target shape. Traditional positioning solutions, such as GPS or multilateration are not applicable in the micro-world, and maps sharing does not scale. In the literature, if we want a self-reconfiguration of microrobots to a target shape that consists of millions of positions, each microrobot should have a memory capacity of at least million positions. Therefore, this is not scalable. In this paper, nodes do not record any position. We present self-reconfiguration methods where nodes are unaware of their positions and where they do not have the final coordinates of each microrobot. In other words, nodes do not store the coordinates that build the target shape. Therefore, memory usage for each node is hugely reduced to and communications are limited to neighboring nodes. These algorithms aim to improve the logical topology of a set of microrobots by restructuring their physical topology. To that end, we consider here the case of restructuring a set of microrobots from a chain to a square and we study two algorithms: the first algorithm ensures the connectivity of the network at the end of the algorithm, where the second guarantees the connectivity of the network through the execution time. The paper presents both analytical and experimental assessments of the algorithms performances using the declarative language and executed under the Dynamic Physical Rendering Simulator (DPRSim).

关键词： distributed algorithm Self-reconfiguration Energy-efficiency Mobility MEMS microrobot

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