Jean Carle, Antoine Gallais and David Simplot-Ryl IRCICA/LIFL, Univ. Lille 1, INRIA Futurs, France

1. Preserving Area Coverage in Wireless Sensor Networks by using Surface Coverage Relay Dominating Sets Jean Carle, Antoine Gallais and David Simplot-Ryl IRCICA/LIFL, Univ. Lille 1, INRIA Futurs, France ISCC 2005 Speaker：Shih-Yun, Hsu

2. Outline • Introduction • Assumption • Related works • Surface Coverage Relays - Connected Area Dominating Set (SCR-CADS) Algorithm • Relay Selection Phase • Decision Phase • Experimental Results • Conclusions

3. Introduction • Sensor nodes are low-cost, low-power, and multi-functional devices • Sensor nodes are deployed over hostile or remote environments to monitor a target area • Sensor nodes could monitor the whole environment • The network lifetime is important • Connected Area Dominating Set (CADS)

4. Introduction • Dominating sets • Dominating Set (DS) • Connected Dominating Set (CDS) • Area Dominating Set (ADS) • Connected Area Dominating Set (CADS)

5. Introduction A C B F E D G H

6. Dominating Set (DS) A C B F E D G H

7. Connected Dominating Set (CDS) A C B F E D G H

8. Area Dominating Set (ADS) A C B F E D G H

9. Connected Area Dominating Set (CADS) A C B F E D G H

10. Assumption • Sensing range is equal to communication range • Each node has a unique priority • Battery state • Identifier • Sensor nodes know their respective position • Positioning issue has already been addressed in other papers

11. Related works • A Coverage-Preserving Node Scheduling Scheme for Large Wireless Sensor Networks • WSNA workshop 2002 • Propose a scheduling scheme which allows nodes to sleep or to remain active without compromising the network monitoring task • Blind point

12. Related works Blind Point B E A D F C

13. Related works B A D C

14. Surface Coverage Relays - Connected Area Dominating Set (SCR-CADS) Algorithm • Relay Selection Phase • Decision Phase

15. Relay Selection Phase • Computing connected dominated sets with multipoint relays • INRIA, Tech. Rep. 4597, Oct. 2002. • MultiPoint Relay (MPR) • Each two hop neighbor of the nodes has a neighbor in MPR set

16. Relay Selection Phase C F B A D E Sort(A)={C, E, F, D} Sort(A)={C, E} Sort(A)={NULL} Sort(A)={C, E, F} Sort(A)={C}

17. Relay Selection Phase • The node collects information of its neighbors • The node computes its own SCR set • The node broadcasts it to its neighbors

18. Decision Phase B B A A D E E C C F F Sort(A)={B, C, E, D} Sort(C)={…., F}

19. Decision Phase • The node collects relay sets and priorities of its neighbors • The node decides to be active if it has the highest priority or if its identifier is in the relay set of the neighbor with highest priority

20. Experimental Results • Experimental field：50 × 50 • Sensing range = communication range = 10 • Battery：100 units

21. Experimental Results

22. Experimental Results

23. Experimental Results

24. Conclusions • Surface Coverage Relays - Connected Area Dominating Set (SCR-CADS) • Without complex computation • Sensing range and communication are equal • Saves energy and prolongs the network lifetime • This provides energy savings and so prolongs the • network lifetime.

25. Thank You!!