1. RELAX : An Energy Efficient Multipath Routing Protocol for Wireless Sensor Networks Bashir Yahya, Jalel Ben-Othman University of Versailles, France ICC 2010

2. Outline Introduction Related Work RELAX Protocol Performance Evaluation Conclusion

3. Introduction Routing in sensor networks is a very challenging task and different from routing in either wired or other wireless networks

4. Introduction Routing techniques can be classified according to the protocol operation into ◦ Negotiation based ◦ Query based ◦ QoS based ◦ Multipath based

5. Introduction Routing techniques can be classified according to the protocol operation into ◦ Negotiation based  Have the objective to eliminate the redundant data ◦ Query based ◦ QoS based ◦ Multipath based

6. Introduction Routing techniques can be classified according to the protocol operation into ◦ Negotiation based ◦ Query based  Sink broadcast a query for data over the network ◦ QoS based ◦ Multipath based

7. Introduction Routing techniques can be classified according to the protocol operation into ◦ Negotiation based ◦ Query based ◦ QoS based  Make a tradeoff between the energy consumption and some QoS metrics before delivering ◦ Multipath based

8. Introduction Routing techniques can be classified according to the protocol operation into ◦ Negotiation based ◦ Query based ◦ QoS based ◦ Multipath based  Improve the network performance in terms of reliability and robustness

9. Introduction Classical multipath routing has been explored for two reasons ◦ Load balance  Disjoint paths  Longer lifetime ◦ Increase reliable data delivery

10. Related Work Directed Diffusion ◦ Maintain an interest cache ◦ Selecting good paths Drawback ◦ Requires periodic interest broadcast ◦ More energy consumption in control traffic C. Intanagonwiwat, R. Govindan, D. Estrin “Directed Diffusion: A Scalable and Robust Communication Paradigm for Sensor Networking.”, ACM MobiCom 2000.

11. Related Work N-to-1 ◦ Finds different node-disjoint paths ◦ Spanning tree structure ◦ Distribute the traffic in order to improve the reliability and security of the data transmission Drawback ◦ Not consider the node’s energy level ◦ Lacks of an efficient load balancing mechanism to distribute the traffic in an energy efficient manner W. Lou, “An efficient N-to-1 mutlipath routing protocol in wireless sensor networks”, MASS 2005.

12. Motivation Improving energy efficiency in routing protocols mainly is based on ◦ Reducing the overhead caused by  Control traffic during construction and maintenance phase  Selecting good routes that reduce energy through an appropriate cost function

13. Goal Minimize the energy consumption through distributing and balancing the load across the multiple paths

14. RELAX Protocol Assumption ◦ N identical sensor nodes ◦ Distributed randomly ◦ Multihop ◦ Same transmission range ◦ Two alkaline batteries(15 mins) ◦ Each node compute its  Residual energy  Available duffer size  Link quality between itself and its neighboring node’s SNR

15. RELAX Protocol Battery Issues ◦ Capacity 、 Recovery(Relaxation Phenomenon) : Battery capacity (245,910) : non-linear battery behavior during charging and discharging periods(4,034) : Battery lifetime : Discharging current D. Rakhmatov, S. Vrudhula, “An Analytical High Level Battery Model for Use in Energy Management of Portable Electronic Systems,” ICCAD, 2001.

16. RELAX Protocol Initialization phase ◦ Hello message ◦ Cost function ◦ RREQ message ◦ Total cost The set of neighbors of x Current residual energy of y Available buffer size of y SNR for the link xy Y. M. Lu, V. W. S. Wong, “An energy multipath routing protocol for wireless sensor networks”, International Journal of communication system, 2007. (SNR) nodeslink costs

17. RELAX Protocol Path discovery phase ◦ Accept only one RREQ message

18. RELAX Protocol Route Refreshing ◦ Source periodically floods a KEEPALIVE message Next-Hop-ID

19. RELAX Protocol Traffic allocation and Data Transmission ◦ A subset of the available paths(N paths) to transfer the message in order to  Distribute the load  Avoid the fast battery drains

20. RELAX Protocol Traffic allocation and Data Transmission ◦ Paths Selection S. Dulman, T. Nieberg, J. Wu, P. Havinga, “Trade-off between Traffic Overhead and Reliability in Multipath Routing for Wireless Sensor Networks”, WCNC-2003.

21. RELAX Protocol Traffic allocation and Data Transmission ◦ Message Segmentation and FEC Codes Generation (where M < k) Z. Xiong; Z. Yang; W. Liu; Z. Feng, “A Lightweight FEC Algorithm for Fault Tolerant Routing in Wireless Sensor Networks”, WiCOM 2006.

22. RELAX Protocol Message Forwarding and Recovery

23. Performance Evaluation

24. Average Energy Consumption

25. Performance Evaluation Average Delivery Ratio

26. Performance Evaluation Average Delay

27. Performance Evaluation Average Node Lifetime

28. Performance Evaluation Average Energy Consumption

29. Performance Evaluation Average Delivery Ratio

30. Performance Evaluation Average Delay

31. Performance Evaluation Average Node Lifetime

32. Conclusion RELAX protocol utilizes the relaxation effect of the battery to increase the overall lifetime of the sensor network Simulation results show that RELAX protocol achieves more energy savings, lower average delay, higher delivery ratio, and long node lifetime duration than other protocols