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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 Chou1, Kuo-Feng Ssu2, Hewijin Christine Jiau2, Wei-Tong Wang2 and Chao Wang2
1Institute for Information Industry, Taiwan2National 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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EA
Dead-End Free Topology Construction
N
Sleeping neighbors
Active neighbors
Transmission range
Undecided neighbors
B
C
D
FActive Neighbor Set (ANS)
A B C F
Tentative Neighbor Set (TNS)
D E
F
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Active Node Selection Algorithm
Ruled
The distance between the candidate node and the initiator
AN
B
C
D
F
E
F
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Active Node Selection Algorithm
Rules
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
r
d
r
ncs aia
1
drule 5.0
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 aid
srule 5.0ruledrules
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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.
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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.
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F
Dead-End Free Topology Maintenance
Local Topology Maintenance Some of the active nodes may suddenly become unavailable.
AN
B
C
D
EE
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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
5/15
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Number of Active Nodes50 nodes 75 nodes
100 nodes
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Number of Survived Nodes50 nodes 75 nodes
100 nodes
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Packet Delivery Ratio50 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 ~