1. LORD: A Localized, Reactive and Distributed Protocol for Node Scheduling in Wireless Sensor Networks Arijit Ghosh and Tony Givargis Center for Embedded Computer Systems Department of Computer Science Design, Automation, and Test in Europe Conference and Exhibition (DATE’05)

2. Outline Introduction The LORD protocol SimulationConclusion

3. Introduction Energy is a major design bottleneck in wireless sensor network –System energy conservation by reduction of active nodes This paper propose a distributed node- scheduling protocol –Maintains coverage –The number of scheduled nodes is minimized

4. Introduction The node-scheduling problem is to identify a minimal subset C of The node-scheduling problem is to identify a minimal subset C of F that covers A. More specifically, compute C: F = {s 1,s 2,…,sŋ}

5. Introduction SiSi SjSj SkSk SmSm S m is a redundant sensor SlSl

6. The LORD protocol Set-up phase –All the sensors individually run a heuristic algorithm to decide their initial state The steady phase –All dying sensors run a localized heuristic algorithm and nominate the sleeping sensors that can cover for themselves

7. The LORD protocol ~set-up Each sensor first builds up its list of neighbors, s i.NL

8. The LORD protocol ~set-up s 1.NL={s 3,s 4.s 5 }

9. The LORD protocol ~set-up The sensor s i defers its decision on its intial state untilall sensors sj such that sj ∈ s i.NL and j < i have made their decisions

10. The LORD protocol ~set-up

11. Simulation 50m x 50m The sensing area of each is equal to its communication area and both are set to be a circle of radius 10m We deploy 80, 90, 100, 110, 120 and 130 sensors

12. The LORD protocol ~set-up To eliminate this redundancy, each ON sensor s i reevaluates its initial decision.

13. The LORD protocol ~set-up sleep

14. The LORD protocol ~steady

15. The LORD protocol ~set-up s 1.NL={s 3,s 4.s 5 }

16. Simulation ~System Lifetime

17. Simulation ~Communication

18. Simulation ~Communication overhead

19. Conclusion we have presented a distributed, localized and reactive protocol for node-scheduling in a sensor network. As future work, we intend to incorporate other system dependent parameters, like routing and communication, in our protocol.

20. Thank You!!