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A Dead-End Free Topology Maintenance Protocol for Geographic Forwarding in Wireless Sensor Networks IEEE Transactions on Computers, vol. 60, no. 11, November 2011 Chih-Hsun Anthony Chou 1, Kuo-Feng Ssu 2, Hewijin Christine Jiau 2, Wei-Tong Wang 2 and Chao Wang 2 1 Institute for Information Industry, Taiwan 2 National Cheng Kung University, Taiwan
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Outline Introduction Assumptions and Background Dead-End Free Topology Maintenance (DFTM) Protocol Discussions and Analysis Experimental Results Conclusion
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Introduction Topology management schemes have emerged as a promising strategy for prolonging the lifetimes of wireless sensor networks. Several schemes construct a virtual communication backbone by turning off redundant sensor nodes. a connected dominating set (CDS)
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Introduction The CDS is constructed in such a way Each node is either a member of the subset or is a neighbor of one of the nodes in the subset. S D
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Introduction Dead-End Node Problem This paper proposes a topology maintenance scheme for the construction of dead-end free topologies in WSNs.
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Assumptions and Background There are many stationary sensors distributed over the monitoring region. The network is assumed to be sufficiently dense to construct a dead-end free topology. Each sensor can be in either an active mode or a sleep mode. Each sensor knows both its own and all its neighbors’ coordinates.
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DFTM Scheme Dead-End Free Verification Dead-End Free Topology Construction Dead-End Free Topology Maintenance
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Dead-End Free Verification Global Dead-End Free (GDF) Condition The dead-end situation does not occur at any node in the network Local Dead-End Free (LDF) Condition N A Sleeping neighbors Active neighbors Node N does not satisfy the LDF condition. Node N satisfies the LDF condition. Transmission range
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A Dead-End Free Topology Construction N Sleeping neighbors Active neighbors Transmission range Undecided neighbors B C D E Active Neighbor Set (ANS) A B C Tentative Neighbor Set (TNS) D E F F Node N does not satisfy the LDF condition. Active Node Selection Algorithm
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E A Dead-End Free Topology Construction N Sleeping neighbors Active neighbors Transmission range Undecided neighbors B C D F Active Neighbor Set (ANS) A B C F Tentative Neighbor Set (TNS) D E F
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Active Node Selection Algorithm Rule d The distance between the candidate node and the initiator A N B C D F E F
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Active Node Selection Algorithm Rule s The length of the new covered segment A N B C D F E F
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Active Node Selection Algorithm Preference weighting i: initiator r: the node’s transmission range ncs a : the length of the new covered segment of node a : the distance from node i to node a rule d rule s
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Dead-End Free Topology Maintenance Global Topology Maintenance For energy balancing All nodes change modes to undecided every T global seconds. The sink node randomly chooses a node to be the initiator. Every node has an equal probability of becoming an active node.
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F Dead-End Free Topology Maintenance Local Topology Maintenance Some of the active nodes may suddenly become unavailable. A N B C D E E
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Discussions and Analysis Discussions Lemma 1. A network topology is fully connected if it satisfies the Global Dead-End Free (GDF) condition. Theorem 1. A network topology constructed by the proposed DFTM scheme is fully connected.
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Discussions and Analysis Analysis The total number of active nodes required in GAF and DFTM. GAF
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Discussions and Analysis Analysis The total number of active nodes required in GAF and DFTM. DFTM – Best Case
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Discussions and Analysis Analysis The total number of active nodes required in GAF and DFTM. DFTM – Worst Case
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Discussions and Analysis Analysis The total number of active nodes required in GAF and DFTM. d
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Experimental Results ns2 Simulator 50, 75, or 100 static nodes were randomly distributed within a sensing area measuring 60*30 m. Transmission range of each node: 15 m. Comparisons: GPSR, GAF and SPAN The length of each GAF square was set to m. SPAN: backbone infrastructure
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Number of Active Nodes 50 nodes 75 nodes 100 nodes
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Number of Survived Nodes 50 nodes 75 nodes 100 nodes
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Packet Delivery Ratio 50 nodes 75 nodes 100 nodes
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Energy Consumption and Path Length
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Comparison for Dead-End Occurrence 50 nodes 100 nodes
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Conclusion This paper presented a distributed dead-end free topology maintenance protocol, namely DFTM. DFTM can be integrated with any geographic routing Low energy consumption A minimum number of dead-end events The performance of DFTM has been benchmarked against that of GAF and SPAN using the ns2 simulator.
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Thank You ~
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