The Experts below are selected from a list of 76851 Experts worldwide ranked by ideXlab platform
Qian Zhang - One of the best experts on this subject based on the ideXlab platform.
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opportunity based Topology Control in wireless sensor networks
IEEE Transactions on Parallel and Distributed Systems, 2010Co-Authors: Yunhuai Liu, Qian ZhangAbstract:Topology Control is an effective method to improve the energy efficiency of wireless sensor networks (WSNs). Traditional approaches are based on the assumption that a pair of nodes is either "connected" or "disconnected." These approaches are called connectivity-based Topology Control. In real environments, however, there are many intermittently connected wireless links called lossy links. Taking a succeeded lossy link as an advantage, we are able to construct more energy-efficient topologies. Toward this end, we propose a novel opportunity-based Topology Control. We show that opportunity-based Topology Control is a problem of NP-hard. To address this problem in a practical way, we design a fully distributed algorithm called CONREAP based on reliability theory. We prove that CONREAP has a guaranteed performance. The worst running time is O(\vert E\vert ), where E is the link set of the original Topology, and the space requirement for individual nodes is O(d), where d is the node degree. To evaluate the performance of CONREAP, we design and implement a prototype system consisting of 50 Berkeley Mica2 motes. We also conducted comprehensive simulations. Experimental results show that compared with the connectivity-based Topology Control algorithms, CONREAP can improve the energy efficiency of a network up to six times.
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opportunity based Topology Control in wireless sensor networks
International Conference on Distributed Computing Systems, 2008Co-Authors: Yunhuai Liu, Qian ZhangAbstract:Topology Control is an effective method to improve the energy efficiency of wireless sensor networks (WSNs). Traditional approaches are based on the assumption that a pair of nodes is either "connected" or "disconnected". These approaches are called connectivity-based Topology Control. In real environments however, there are many intermittently connected wireless links called lossy links. Taking a succeeded lossy link as an advantage, we are able to construct more energy-efficient topologies. Towards this end, we propose a novel opportunity-based Topology Control. We show that opportunity-based Topology Control is a problem of NPhard. To address this problem in a practical way, we design a fully distributed algorithm called CONREAP based on reliability theory. We prove that CONREAP has a guaranteed performance. The worst running time is O(jEj) where E is the link set of the original Topology, and the space requirement for individual nodes is O(d) where d is the node degree. To evaluate the performance of CONREAP, we design and implement a prototype system consisting of 50 BerkeleyMica2 motes. We also conducted comprehensive simulations. Experimental results show that compared with the connectivity-based Topology Control algorithms, CONREAP can improve the energy efficiency of a network up to 6 times.
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joint Topology Control and routing in ieee 802 11 based multiradio multichannel mesh networks
IEEE Transactions on Vehicular Technology, 2007Co-Authors: Lin Chen, Qian Zhang, Weijia JiaAbstract:Due to low cost, ease of deployment, increased coverage, and enhanced capacity, multiradio mesh networks that utilize inexpensive and readily available Institute of Electrical and Electronics Engineers (IEEE) 802.11 wireless interfaces are touted as the new frontier of wireless networking. In a multihop mesh system, the close interaction between Topology Control and routing selection affects the system throughput of a wireless network. This paper proposes a novel joint Topology Control and routing (JTCR) protocol for a multiradio multichannel wireless mesh network to exploit both channel diversity and spatial reusability. It resides between medium access Control and the network layer and aims to improve the network throughput by coordinating transmission power, channel assignment, and route selection among multiple nodes in a distributed way. JTCR jointly coordinates the transmission power at each node, the channel selection on each wireless interface, and the route selection among interfaces based on the traffic information that is measured and exchanged among two-hop neighbor nodes. An equivalent channel air time metric (ECATM) is presented to quantify the difference of various adjustment candidates. This protocol achieves the efficient utilization of available channels by selecting a feasible adjustment candidate with the smallest EC ATM value and coordinating affected nodes to realize the adjustment. Our NS-2-based simulation results show that the network throughput can be significantly improved by using our proposed solution.
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energy efficient localized Topology Control algorithms in ieee 802 15 4 based sensor networks
IEEE Transactions on Parallel and Distributed Systems, 2007Co-Authors: Min Gao, Qian ZhangAbstract:Sensor networks have emerged as a promising technology with various applications, where power efficiency is one of the critical requirements. The recent IEEE 802.15.4 standard offers a promising platform for wireless sensor networks. Since each node can act as a coordinator or a device in the IEEE 802.15.4 standard, 802.15.4-based sensor networks have various possible network topologies. To reduce power consumption, in this paper, we try to construct network topologies with a small number of coordinators while still maintaining network connectivity. By reducing the number of coordinators, the average duty cycle is reduced and the battery life is prolonged. Three Topology Control algorithms are proposed in this paper. Self-pruning (SP) is the simplest one with O(1) running time and provides the shortest path to the sink node. Ordinal pruning (OP) can significantly improve SP in terms of power saving with O(n) running time. Layered pruning (LP) is a trade off between the first two pruning algorithms with O(radicn) running time and has a slightly higher power consumption than OP. Furthermore, all three algorithms are independent of the physical radio propagation characteristics. Extensive simulations have been performed to verify the effectiveness of the proposed Topology Control schemes
Quansheng Guan - One of the best experts on this subject based on the ideXlab platform.
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joint Topology Control and authentication design in mobile ad hoc networks with cooperative communications
IEEE Transactions on Vehicular Technology, 2012Co-Authors: Quansheng Guan, Shengming Jiang, Victor C. M. LeungAbstract:Security is the main concern and bottleneck for widely deployed wireless applications due to the fact that wireless channels are vulnerable to attacks and that wireless bandwidth is a constrained resource. In this sense, it is desirable to adaptively achieve security according to the available resource. In particular, mobile ad hoc networks (MANETs) based on cooperative communication (CC) present significant challenges to security issues, as well as issues of network performance and management. In this paper, we focus on authentication and Topology Control issues. Although authentication and Topology Control are separately studied in most existing works, they are, in fact, closely correlated in MANETs. For example, both authentication and Topology Control schemes have significant impacts on throughput. In this paper, we jointly consider authentication and Topology Control. Specifically, we analyze the effective throughput with upper layer authentication schemes and physical-layer schemes related to channel conditions and relay selections for CCs. A joint authentication and Topology Control (JATC) scheme is proposed to improve the throughput. JATC is formulated as a discrete stochastic optimization problem, which does not require prior perfect channel status but only channel estimate. We also mathematically prove the tracking convergence property and the convergence rate of the discrete stochastic optimization approach in this paper. Simulation results show that our scheme can substantially improve throughput in MANETs with CC.
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capacity optimized Topology Control for manets with cooperative communications
IEEE Transactions on Wireless Communications, 2011Co-Authors: Quansheng Guan, Shengming Jiang, Victor C. M. LeungAbstract:Cooperative communications can significantly enhance transmission reliability and bandwidth efficiency in wireless networks. However, many upper layer aspects of cooperative communications merit further research. In this paper, we investigate its impacts on network Topology and network capacity, which is determined by considerable aspects, such as physical layer capacity, interference, path length, etc. Since cooperative communications enhance physical layer capacity and relay selection impacts network Topology directly, we present a Capacity-Optimized COoperative (COCO) Topology Control scheme for mobile ad hoc networks (MANETs) with cooperative communications. We consider both upper layer network capacity and physical layer relay selections in the proposed scheme. In addition, only the channel estimate, not the perfect channel status, is assumed to be known in our scheme. The Topology Control problem in MANETs is then formulated as a discrete stochastic optimization problem, which can be solved using a stochastic approximation approach. Further, an improved COCO is presented to reconfigure network Topology to track the changing mobile environment dynamically. Simulation results are presented to show the effectiveness of the proposed scheme.
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prediction based Topology Control and routing in cognitive radio mobile ad hoc networks
IEEE Transactions on Vehicular Technology, 2010Co-Authors: Quansheng Guan, Shengming Jiang, Gang WeiAbstract:Recent research activities on cognitive radio (CR) have mainly focussed on opportunistic spectrum access and spectrum utilization. However, CR technology will have a significant impact on upper layer performance in wireless networks, particularly in mobile ad hoc networks (MANETs). In this paper, we study Topology Control and routing issues in CR-MANETs and propose a distributed prediction-based cognitive Topology Control (PCTC) scheme to provision cognition capability to routing in CR-MANETs. PCTC is a middleware-like cross-layer module residing between CR module and routing. It uses cognitive link availability prediction, which is aware of the interference to primary users and user mobility, to predict the available duration of links. Based on the link prediction, PCTC captures the dynamic changes of the Topology and constructs an efficient and reliable Topology, which is aimed at mitigating rerouting frequency and improving end-to-end network performance such as throughput and delay. Simulation results are presented to show the effectiveness of the proposed scheme.
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prediction based Topology Control and routing in cognitive radio mobile ad hoc networks
Conference on Computer Communications Workshops, 2010Co-Authors: Quansheng Guan, Shengming JiangAbstract:Cognitive radio (CR) technology will have significant impacts on upper layer performance in mobile ad hoc networks (MANETs). In this paper, we study Topology Control and routing in CR-MANETs. We propose a distributed Prediction-based Cognitive Topology Control (PCTC) scheme to provision cognition capability to routing in CR-MANETs. PCTC is a midware-like cross-layer module residing between CR module and routing. The proposed PCTC scheme uses cognitive link availability prediction, which is aware of the interference to primary users, to predict the available duration of links in CR-MANETs. Based on the link prediction, PCTC constructs an efficient and reliable Topology, which is aimed at mitigating re-routing frequency and improving end-to-end network performance such as throughput and delay. Simulation results are presented to show the effectiveness of the proposed scheme.
Shengming Jiang - One of the best experts on this subject based on the ideXlab platform.
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joint Topology Control and authentication design in mobile ad hoc networks with cooperative communications
IEEE Transactions on Vehicular Technology, 2012Co-Authors: Quansheng Guan, Shengming Jiang, Victor C. M. LeungAbstract:Security is the main concern and bottleneck for widely deployed wireless applications due to the fact that wireless channels are vulnerable to attacks and that wireless bandwidth is a constrained resource. In this sense, it is desirable to adaptively achieve security according to the available resource. In particular, mobile ad hoc networks (MANETs) based on cooperative communication (CC) present significant challenges to security issues, as well as issues of network performance and management. In this paper, we focus on authentication and Topology Control issues. Although authentication and Topology Control are separately studied in most existing works, they are, in fact, closely correlated in MANETs. For example, both authentication and Topology Control schemes have significant impacts on throughput. In this paper, we jointly consider authentication and Topology Control. Specifically, we analyze the effective throughput with upper layer authentication schemes and physical-layer schemes related to channel conditions and relay selections for CCs. A joint authentication and Topology Control (JATC) scheme is proposed to improve the throughput. JATC is formulated as a discrete stochastic optimization problem, which does not require prior perfect channel status but only channel estimate. We also mathematically prove the tracking convergence property and the convergence rate of the discrete stochastic optimization approach in this paper. Simulation results show that our scheme can substantially improve throughput in MANETs with CC.
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capacity optimized Topology Control for manets with cooperative communications
IEEE Transactions on Wireless Communications, 2011Co-Authors: Quansheng Guan, Shengming Jiang, Victor C. M. LeungAbstract:Cooperative communications can significantly enhance transmission reliability and bandwidth efficiency in wireless networks. However, many upper layer aspects of cooperative communications merit further research. In this paper, we investigate its impacts on network Topology and network capacity, which is determined by considerable aspects, such as physical layer capacity, interference, path length, etc. Since cooperative communications enhance physical layer capacity and relay selection impacts network Topology directly, we present a Capacity-Optimized COoperative (COCO) Topology Control scheme for mobile ad hoc networks (MANETs) with cooperative communications. We consider both upper layer network capacity and physical layer relay selections in the proposed scheme. In addition, only the channel estimate, not the perfect channel status, is assumed to be known in our scheme. The Topology Control problem in MANETs is then formulated as a discrete stochastic optimization problem, which can be solved using a stochastic approximation approach. Further, an improved COCO is presented to reconfigure network Topology to track the changing mobile environment dynamically. Simulation results are presented to show the effectiveness of the proposed scheme.
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prediction based Topology Control and routing in cognitive radio mobile ad hoc networks
IEEE Transactions on Vehicular Technology, 2010Co-Authors: Quansheng Guan, Shengming Jiang, Gang WeiAbstract:Recent research activities on cognitive radio (CR) have mainly focussed on opportunistic spectrum access and spectrum utilization. However, CR technology will have a significant impact on upper layer performance in wireless networks, particularly in mobile ad hoc networks (MANETs). In this paper, we study Topology Control and routing issues in CR-MANETs and propose a distributed prediction-based cognitive Topology Control (PCTC) scheme to provision cognition capability to routing in CR-MANETs. PCTC is a middleware-like cross-layer module residing between CR module and routing. It uses cognitive link availability prediction, which is aware of the interference to primary users and user mobility, to predict the available duration of links. Based on the link prediction, PCTC captures the dynamic changes of the Topology and constructs an efficient and reliable Topology, which is aimed at mitigating rerouting frequency and improving end-to-end network performance such as throughput and delay. Simulation results are presented to show the effectiveness of the proposed scheme.
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prediction based Topology Control and routing in cognitive radio mobile ad hoc networks
Conference on Computer Communications Workshops, 2010Co-Authors: Quansheng Guan, Shengming JiangAbstract:Cognitive radio (CR) technology will have significant impacts on upper layer performance in mobile ad hoc networks (MANETs). In this paper, we study Topology Control and routing in CR-MANETs. We propose a distributed Prediction-based Cognitive Topology Control (PCTC) scheme to provision cognition capability to routing in CR-MANETs. PCTC is a midware-like cross-layer module residing between CR module and routing. The proposed PCTC scheme uses cognitive link availability prediction, which is aware of the interference to primary users, to predict the available duration of links in CR-MANETs. Based on the link prediction, PCTC constructs an efficient and reliable Topology, which is aimed at mitigating re-routing frequency and improving end-to-end network performance such as throughput and delay. Simulation results are presented to show the effectiveness of the proposed scheme.
J. C. Hou - One of the best experts on this subject based on the ideXlab platform.
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Topology Control for maintaining network connectivity and maximizing network capacity under the physical model
International Conference on Computer Communications, 2008Co-Authors: Yan Gao, J. C. Hou, Hoang NguyenAbstract:In this paper we study the issue of Topology Control under the physical signal-to-interference-noise-ratio (SINR) model, with the objective of maximizing network capacity. We show that existing graph-model-based Topology Control captures interference inadequately under the physical SINR model, and as a result, the interference in the Topology thus induced is high and the network capacity attained is low. Towards bridging this gap, we propose a centralized approach, called spatial reuse maximizer (MaxSR), that combines a power Control algorithm T2P with a Topology Control algorithm P2T. T2P optimizes the assignment of transmit power given a fixed Topology, where by optimality we mean that the transmit power is so assigned that it minimizes the average interference degree (defined as the number of interfering nodes that may interfere with the ongoing transmission on a link) in the Topology. P2T, on the other hand, constructs, based on the power assignment made in T2P, a new Topology by deriving a spanning tree that gives the minimal interference degree. By alternately invoking the two algorithms, the power assignment quickly converges to an operational point that maximizes the network capacity. We formally prove the convergence of MaxSR. We also show via simulation that the Topology induced by MaxSR outperforms that derived from existing Topology Control algorithms by 50%-110% in terms of maximizing the network capacity.
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Localized fault-tolerant Topology Control in wireless ad hoc networks
IEEE Transactions on Parallel and Distributed Systems, 2006Co-Authors: N. Li, J. C. HouAbstract:Topology Control algorithms have been proposed to maintain network connectivity while improving energy efficiency and increasing network capacity. However, by reducing the number of links in the network, Topology Control algorithms actually decrease the degree of routing redundancy. As a result, the derived Topology is more susceptible to node failures or departures. In this paper, we resolve this problem by enforcing k-vertex connectivity in the Topology construction process. We propose a fully localized algorithm, fault-tolerant local spanning subgraph (FLSS), that can preserve k-vertex connectivity and is min-max optimal among all strictly localized algorithms (i.e., FLSS minimizes the maximum transmission power used in the network, among all strictly localized algorithms that preserve k-vertex connectivity). It can also be proved that FLSS outperforms two other existing localized algorithms in terms of reducing the transmission power. We also discuss how to relax several widely used assumptions in Topology Control to increase the practical utility of FLSS. Simulation results indicate that, compared with existing distributed/localized fault-tolerant Topology Control algorithms, FLSS not only has better power-efficiency, but also leads to higher network capacity. Moreover, FLSS is robust with respect to position estimation errors.
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localized Topology Control algorithms for heterogeneous wireless networks
IEEE ACM Transactions on Networking, 2005Co-Authors: J. C. HouAbstract:Most existing Topology Control algorithms assume homogeneous wireless networks with uniform maximal transmission power, and cannot be directly applied to heterogeneous wireless networks where the maximal transmission power of each node may be different. We present two localized Topology Control algorithms for heterogeneous networks: Directed Relative Neighborhood Graph (DRNG) and Directed Local Spanning Subgraph (DLSS). In both algorithms, each node independently builds its neighbor set by adjusting the transmission power, and defines the network Topology by using only local information. We prove that: 1) both DRNG and DLSS can preserve network connectivity; 2) the out-degree of any node in the resulting Topology generated by DRNG or DLSS is bounded by a constant; and 3) DRNG and DLSS can preserve network bi-directionality. Simulation results indicate that DRNG and DLSS significantly outperform existing Topology Control algorithms for heterogeneous networks in several aspects.
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flss a fault tolerant Topology Control algorithm for wireless networks
ACM IEEE International Conference on Mobile Computing and Networking, 2004Co-Authors: J. C. HouAbstract:Topology Control algorithms usually reduce the number of links in a wireless network, which in turn decreases the degree of connectivity. The resulting network Topology is more susceptible to system faults such as node failures and departures. In this paper, we consider k-vertex connectivity of a wireless network. We first present a centralized algorithm, Fault-tolerant Global Spanning Subgraph (FGSSk), which preserves k-vertex connectivity. FGSSk is min-max optimal, i.e., FGSSk minimizes the maximum transmission power used in the network, among all algorithms that preserve k-vertex connectivity. Based on FGSSk, we propose a localized algorithm, Fault-tolerant Local Spanning Subgraph (FLSSk). It is proved that FLSSk preserves k-vertex connectivity while maintaining bi-directionality of the network, and FLSSk is min-max optimal among all strictly localized algorithms. We then relax several widely used assumptions for Topology Control to enhance the practicality of FGSSk and FLSSk. Simulation results show that FLSSk is more power-efficient than other existing distributed/localized Topology Control algorithms.
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Topology Control in heterogeneous wireless networks problems and solutions
International Conference on Computer Communications, 2004Co-Authors: J. C. HouAbstract:Previous work on Topology Control usually assumes homogeneous wireless nodes with uniform transmission ranges. In this paper, we propose two localized Topology Control algorithms for heterogeneous wireless multihop networks with nonuniform transmission ranges: directed relative neighborhood graph (DRNG) and directed local minimum spanning tree (DLMST). In both algorithms, each node selects a set of neighbors based on the locally collected information. We prove that (1) the topologies derived under DRNG and DLMST preserve the network connectivity; (2) the out degree of any node in the resulting Topology by DLMST is bounded; while the out degree of nodes in the Topology by DRNG is not bounded; and (3) the topologies generated by DRNG and DLMST preserve the network bi-directionality.
Victor C. M. Leung - One of the best experts on this subject based on the ideXlab platform.
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joint Topology Control and authentication design in mobile ad hoc networks with cooperative communications
IEEE Transactions on Vehicular Technology, 2012Co-Authors: Quansheng Guan, Shengming Jiang, Victor C. M. LeungAbstract:Security is the main concern and bottleneck for widely deployed wireless applications due to the fact that wireless channels are vulnerable to attacks and that wireless bandwidth is a constrained resource. In this sense, it is desirable to adaptively achieve security according to the available resource. In particular, mobile ad hoc networks (MANETs) based on cooperative communication (CC) present significant challenges to security issues, as well as issues of network performance and management. In this paper, we focus on authentication and Topology Control issues. Although authentication and Topology Control are separately studied in most existing works, they are, in fact, closely correlated in MANETs. For example, both authentication and Topology Control schemes have significant impacts on throughput. In this paper, we jointly consider authentication and Topology Control. Specifically, we analyze the effective throughput with upper layer authentication schemes and physical-layer schemes related to channel conditions and relay selections for CCs. A joint authentication and Topology Control (JATC) scheme is proposed to improve the throughput. JATC is formulated as a discrete stochastic optimization problem, which does not require prior perfect channel status but only channel estimate. We also mathematically prove the tracking convergence property and the convergence rate of the discrete stochastic optimization approach in this paper. Simulation results show that our scheme can substantially improve throughput in MANETs with CC.
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Topology Control in Mobile Ad Hoc Networks with Cooperative Communications
Ieee Wireless Communications, 2012Co-Authors: Q S Guan, F.r. Yu, S.m. Jiang, Victor C. M. Leung, Hamid MehrvarAbstract:Cooperative communication has received tremendous interest for wireless networks. Most existing works on cooperative communications are focused on link-level physical layer issues. Consequently, the impacts of cooperative communications on network-level upper layer issues, such as Topology Control, routing and network capacity, are largely ignored. In this article, we propose a Capacity-Optimized Cooperative (COCO) Topology Control scheme to improve the network capacity in MANETs by jointly considering both upper layer network capacity and physical layer cooperative communications. Through simulations, we show that physical layer cooperative communications have significant impacts on the network capacity, and the proposed Topology Control scheme can substantially improve the network capacity in MANETs with cooperative communications.
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capacity optimized Topology Control for manets with cooperative communications
IEEE Transactions on Wireless Communications, 2011Co-Authors: Quansheng Guan, Shengming Jiang, Victor C. M. LeungAbstract:Cooperative communications can significantly enhance transmission reliability and bandwidth efficiency in wireless networks. However, many upper layer aspects of cooperative communications merit further research. In this paper, we investigate its impacts on network Topology and network capacity, which is determined by considerable aspects, such as physical layer capacity, interference, path length, etc. Since cooperative communications enhance physical layer capacity and relay selection impacts network Topology directly, we present a Capacity-Optimized COoperative (COCO) Topology Control scheme for mobile ad hoc networks (MANETs) with cooperative communications. We consider both upper layer network capacity and physical layer relay selections in the proposed scheme. In addition, only the channel estimate, not the perfect channel status, is assumed to be known in our scheme. The Topology Control problem in MANETs is then formulated as a discrete stochastic optimization problem, which can be solved using a stochastic approximation approach. Further, an improved COCO is presented to reconfigure network Topology to track the changing mobile environment dynamically. Simulation results are presented to show the effectiveness of the proposed scheme.