1. Deploying Sensors for Maximum Coverage in Sensor Network Ruay-Shiung Chang Shuo-Hung Wang National Dong Hwa University IEEE International Wireless Communications & Mobile Computing Conference 2007 (IWCMC 2007)

2. Outline Introduction Self-Deployment by Density Control (SDDC) Simulation Conclusion

3. Introduction In the Wireless Mobile Sensor Network  The application of survivors searching efficiently search quick deployment large search area  The deployment should be considered about the sensing coverage the network communication

4. Introduction ?

7. There is the problem of deciding the moving position  The network partition  The overlapping sensing coverage Goal  To deploy the sensor nodes with larger sensing coverage unconnected networks

8. Assumption Each Sensor  can get the data of obstacles positions  measures the free area  knows the neighbors’ distance and angle by [8]  the communication range > the sensing range Cx=2Sx  has one unique ID [8]Relaxation on a mesh: a formalism for generalized localization", Proceedings of the IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS01), pages 1055--1060, Wailea, Hawaii, Oct 2001 obstacle

9. Self-Deployment by Density Control At the initialization The node exchange the ID with the neighbors  To decide the cluster-header 1 3 2 obstacle Node id 123 Cluster status Node status Any pair of cluster headers are not in the communication range Undecided Not deployed Cluster header member

10. The cluster header  Divides the communication into k equal area  calculates the density in communication range The virtual force  the neighbor nodes  The obstacles Self-Deployment by Density Control 1 3 2 obstacle

11. Density K: the parameter of division the communication area K m : the measure of division of node’s communication area 1 3 2 obstacle area2 area3 area4 area5 area6 area7 area8 area1

12. The theoretical number is calculated by the related work. Density The Geometrical Foundation of Natural Structure: A Source Book of Design R. Williams Dover Pub. Inc., New York, 1979. If R=2r, k=8 N t =0.41 There are 3 neighbors in the communication

13. Density Ratio of actual number and theoretical number The ratio of occupied area measure is defined The free area The obstacle area ratio obstacle area

14. Virtual Force Each node calculates the force within it’s communication area 1 3 2 obstacle area2 area3 area4 area5 area6 area7 area8 area1 The Distance between the node i to nodes j The Distance between the node to obstacle FiFi FoFo

15. Self-Deployment by Density Control In the cluster each node calculate the virtual force

16. Self-Deployment by Density Control The node get the new position and angle from the virtual force The node  Node status : not deployment  Send the sug_msg to the neighbors New position and angle Wait a ask_msg from other neighbor If there is no ask_msg feedback, node still waits a random time interval.

17. Self-Deployment by Density Control Sensors change the node status “not deployment“ to “deployed”  adjust their position until the density lower than the N t  can not moving because the obstacle or other sensors  Moving distance is small than the threshold β

18. Self-Deployment by Density Control The cluster header will communicate with the neighbor cluster header  To compare with the cluster density ratio Density ratio > neighbor’s ratio All cluster move to the neighbor cluster Density ratio <threshold ε The cluster stop moving

19. Simulation Simulator : Stage multi-agent simulator Sensor nodes: 10-100 System parameter  Density ratio threshold : 0.125  Distance threshold: 1.25m The moving speed : 0.6m/s The detection distance of obstacle : 5m

20. Simulation

22. Simulation Results

23. Conclusion This paper proposes the Self-Deployment by Density Control (SDDC) algorithm which deploys the sensor node quickly. The simulation result shows that the algorithm is useful in spread the sensor nodes efficiently.