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A Dead-End Free Topology Maintenance Protocol for Geographic Forwarding in Wireless Sensor Networks. 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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A Dead-End Free Topology Maintenance Protocol for Geographic Forwarding in Wireless Sensor Networks Chih-Hsun Anthony Chou1, Kuo-Feng Ssu2, Hewijin Christine Jiau2, Wei-Tong Wang2 and Chao Wang2 1Institute for Information Industry, Taiwan 2National Cheng Kung University, Taiwan IEEE Transactions on Computers, vol. 60, no. 11, November2011
Outline • Introduction • Assumptions and Background • Dead-End Free Topology Maintenance (DFTM) Protocol • Discussions and Analysis • Experimental Results • Conclusion
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)
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
Introduction • Dead-End Node Problem • This paper proposes a topology maintenance scheme • for the construction of dead-end free topologies in WSNs.
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.
DFTM Scheme • Dead-End Free Verification • Dead-End Free Topology Construction • Dead-End Free Topology Maintenance
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 Node Nsatisfies the LDF condition. Node Ndoes not satisfy the LDF condition. N A Transmission range Sleeping neighbors Active neighbors
Dead-End Free Topology Construction Active Neighbor Set (ANS) F A B C C E N A Tentative Neighbor Set (TNS) D E F D Transmission range B Sleeping neighbors Node Ndoes not satisfy the LDF condition. Active neighbors Undecided neighbors Active Node Selection Algorithm
Dead-End Free Topology Construction Active Neighbor Set (ANS) F F A B C F C E N A Tentative Neighbor Set (TNS) D E D Transmission range B Sleeping neighbors Active neighbors Undecided neighbors
Active Node Selection Algorithm • Ruled • The distance between the candidate node and the initiator F F C E N A D B
Active Node Selection Algorithm • Rules • The length of the new covered segment F F C N E A D B
Active Node Selection Algorithm • Preference weighting rules ruled i: initiator r: the node’s transmission range ncsa: the length of the new covered segment of node a : the distance from node i to node a
Dead-End Free Topology Maintenance • Global Topology Maintenance • For energy balancing • All nodes change modes to undecided every Tglobal seconds. • The sink node randomly chooses a node to be the initiator. • Every node has an equal probability of becoming an active node.
Dead-End Free Topology Maintenance • Local Topology Maintenance • Some of the active nodes may suddenly become unavailable. • Wake up sleeping nodes • Each active node periodically exchanges messages with its active neighbors. • When a node fails to receive an ACK message from a specific neighbor • The neighbor will be removed from the Active Neighbor Set. • Execute the dead-end free topology construction process.
Dead-End Free Topology Maintenance • Local Topology Maintenance • Some of the active nodes may suddenly become unavailable. F C E E N A D B
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.
Discussions and Analysis • Analysis • The total number of active nodes required in GAF and DFTM. GAF
Discussions and Analysis • Analysis • The total number of active nodes required in GAF and DFTM. DFTM – Best Case
Discussions and Analysis • Analysis • The total number of active nodes required in GAF and DFTM. DFTM – Worst Case
Discussions and Analysis • Analysis • The total number of active nodes required in GAF and DFTM. d
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
Number of Active Nodes 75 nodes 50 nodes 100 nodes
Number of Survived Nodes 75 nodes 50 nodes 100 nodes
Packet Delivery Ratio 75 nodes 50 nodes 100 nodes
Comparison for Dead-End Occurrence 100 nodes 50 nodes
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.
