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Lightweight Clustering Scheme for Disaster Relief Wireless Sensor Network1

Hanshin-Awaji earthquake survival rates versus rescue time2

ContentsIntroductionLightweight Clustering schemePerformance evaluationExperimental resultsConclusion

3IntroductionLifetime maximization is very important when designing WSN especially in disaster relief WSNs.Several studies on reducing battery power consumption and extending network lifetimeSensor node with sleep Mode : SMAC, TMAC, DMAC Not practical for rescue operationsClustering: LEACH, LEACH-C, WCA, HEED..So complicated.Need a lightweight clustering scheme with a simple algorithm for rescue operations.

4LiCS did not require exact location information of sensor nodesNo need localization module result in low cost of sensor node and no energy for localization moduleHaving no complex localization algorithmsEfficient and effective way for maximizing the lifetime of a network and the number of communicable sensor nodes.

5Lightweight Clustering scheme

Network and system modelAll sensor nodes are stationary and uniformly distributed in a fieldOnly one SINK node in the wireless sensor networknot have an energy constraint Cluster head cannot change its state to sleep modeCluster heads are elected by a time intervalInitially, each sensor node has the same energy capacity

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Lightweight Clustering scheme

Cluster Head Election Algorithm7

Lightweight Clustering scheme

The target of this clustering scheme is a wireless sensor network that elects cluster heads autonomously. At the first roundCluster head election depends on the sensor node starting time. At the start of a round each sensor node calculates its cluster head announcement (CHA) time. The CHA time is decide by the amount of energy remaining in the sensor node.

Low remaining energy will have a later CHA time.8

The SINK node is just a data collectorNot a network construction coordinator. No parameters have to be sent to the SINK nodeSINK node does not need to calculate which node will be a cluster head in the next round based only on a parameter that has been sent from sensor nodes.

Equation1indicates that a sensor node with low remaining energy will have a later CHA time.

Earlier CHA time become cluster heads, and broadcast CHASensor nodes check any cluster heads around before announcing they are cluster heads. Any cluster heads among their neighbor nodesdo not announce they are cluster heads, and join the nearest cluster as a cluster member. Sensor node that has become a cluster member checks for new cluster heads until an election phase timeout.

9Sensor nodes that have an earlier CHA time become cluster heads, and broadcast their CHA message and end time of round. Sensor nodes check whether any cluster heads around before announcing they are cluster heads. Any cluster heads among their neighbor nodesdo not announce they are cluster heads, and join the nearest cluster as a cluster member. A sensor node that has become a cluster member checks for new cluster heads until an election phase timeout. When a new cluster head is nearer (has a stronger RSSI) than the current cluster head appears, end sensor nodes change their cluster head to the new one. However, if there is no cluster head among its neighbor nodes, a sensor node announces that it is a cluster head. After a round, sensor nodes will start a new election phase and elect cluster heads of the wireless sensor network. Changing their cluster head to the new one has stronger RSSINo cluster head among its neighbor nodes, a sensor node announces that it is a cluster head. After a round, sensor nodes will start a new election phase and elect cluster heads of the wireless sensor network.

10Performance evaluation

Simulation Outline and ParametersEnergy consumption of the wireless sensor node

Energy consumption of a cluster head

Energy consumption of a cluster member

Energy consumption of sensor nodes without a cluster head

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Energy consumption per second of a cluster head in the data collection phase

Energy consumption per second of a cluster head in the cluster head election phase

Energy consumption per second of a cluster member in the data collection phase

Energy consumption per second of a cluster member in the cluster head election phase13

Performance evaluation

Simulation parameters Simulation topology 14

Experimental resultsNumber of communicable nodes

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Performance of LiCS was better than that of LEACHLiCS has the same drop in the numbers of communicable nodes as HEEDLow density network reduces the effectiveness of LEACH, LiCS and HEEDHigh-density pointLEACH: increases the energy consumption of sensor nodes.LiCS and HEED: need more cluster heads were needed makes the node lifetime short.

16Experimental resultsNumber of CHA messages17

LiCS and Heed have the same lifetime. LiCS cover all sensor nodes with fewer CHs than HEED.Transmission frequency of the CHA messages in the election phase decreases A lighter selection algorithm resulted in LiCS having fewer CHA messages than HEED.18ConclusionA simple clustering scheme to increase the lifetime of wireless sensor networks and maximize the number of communicable sensor nodes.The performance of LiCS with a dynamic communication range caused by a radio irregularity will be evaluated in future.

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