Energy-Efficient Shortest Path Self-Stabilizing Multicast Protocol for Mobile Ad Hoc Networks

1. Energy-Efficient Shortest Path Self-Stabilizing Multicast Protocol for Mobile Ad Hoc Networks Ganesh Sridharan Ganesh.Sridharan@asu.edu

2. Outline • Introduction • Goals • System Model • Cost metric • Simulation & Implementation • Conclusion

3. Introduction • Mobile Ad Hoc Networks (MANETs) • No infrastructure • Limited transmission range • Energy constrained • Multicasting in MANETs • Why multicast as opposed to multiple unicast? • Less number of messages • Less energy spent

4. Introduction • Issues in MANET Multicasting • Dynamic Topology • Energy constrained • Possible solution –flooding • Suffers from redundant rebroadcast • Increase in collision and contention • Energy inefficient • Tree or Mesh Structure • Examples: MAODV, ODMRP etc.

5. Shortest Path Self-Stabilizing ProtocolSS-SPST • Shortest path spanning tree from root • Pro active tree construction • Tree includes both multicast group and non-group nodes • Faults • Change in topology caused by mobility • SS-SPST is self-stabilizing • Converge to a global legitimate state from an illegitimate state • Fault-tolerant solution • SS-SPST is distributed • Uses only local knowledge

6. Self-Stabilization • Properties • Convergence • Closure • Inter-communication • Share memory • Message passing • Beaconing • Time complexity • Rounds • Round definition in a lossy medium • A round is defined to be the time period in which each node in the system receives at least one beacon message from each of its neighbors and performs computation based on the information it has received.

7. SS-SPST Cost metric • Multicast tree is constructed to optimize the cost metric • Currently hop count is the cost metric • Goal: To optimize energy • An energy-efficient cost metric is required to minimize total energy consumption

8. Wireless Multicast Advantage X PXY PXZ Y PXZ > PXY Z

9. Motivation - example R NG 2 1 NG NG X Total discard energy = 3 * Reception energy

10. Problem Statement • Propose energy-efficient cost metric • Simulation based performance comparison with MAODV and ODMRP • Comparison of different cost metrics

11. MAODV & ODMRP • MAODV properties • Tree based • On-demand • Route request and route reply phase • ODMRP properties • Mesh based • On-demand • Many routes to the receivers

12. System Model - Assumptions • Unique identification • Periodic beaconing • Soft-state neighbors • Cost metric computation • Dynamic transmission range • Active mode • Single source multicasting

13. Energy Model ETx = Eelec . K + Eamp . K . d2 ERx = Eelec . K Eelec = Fixed energy Eamp = Amplification energy K = Number of bits d = distance

14. SS-SPST - Algorithm If (root) Dist-to-root = 0 Parent = -1 else Dist-to-root = Shortest distance to root through any neighbor node ‘i’ Parent = i

15. SS-SPST An Example R NG 2 1 NG NG X

16. R NG NG NG 1 2 X SS-SPST An Example Round 1 Round 2 Round 3

17. Motivation - example R NG 2 1 NG NG X Total discard energy = 3 * Reception energy

18. Cost metric • Hop count • Cij = 1 • Transmission Energy • Cij = Tij • Transmission Energy based on farthest node • Cij = (Tij + R) if j is the farthest node from i = Rotherwise

19. Cost metric • Transmission Energy based on farthest node with discard energy • Cij = (Tij+R+Li) if j is the farthest node from i = Rotherwise • Li = R * (#neighborsi - #tree childreni)

20. 0 1 6 2 3 4 5 7 8 9 An Example 120.1 120.06 120.02 75.27 120.36 200.03 120.56 120.04 75.37 120.45 120.34 75.49 75.48

21. 0 1 6 2 3 4 5 9 8 7 Hop count metric – SS-SPST Round 1 1 Round 2 1 1 1 1 Round 3 1 1 1 1 • Stabilization time = 3 rounds • Energy consumed / bit = 5.95 micro J

22. 0 1 6 2 3 4 5 7 8 9 Transmission Energy metric –SS-SPST-T Round 1 1.492 Round 2 1.491 1.49 0.617 4.051 Round 3 1.4909 Round 4 1.5 0.618 0.6199 0.619 • Stabilization time = 4 rounds • Energy consumed / bit = 4.72 micro J

23. 0 1 6 2 3 4 5 7 8 9 Max Transmission Energy metric –SS-SPST-F Round 1 1.542 0.05 Round 2 0.05 0.05 0.617 4.101 Round 3 0.05 Round 4 0.05 1.55 Round 5 0.05 0.05 • Stabilization time = 5 rounds • Energy consumed / bit = 3.392 micro J

24. 0 1 6 2 3 4 5 7 8 9 Max Transmission Energy + Discard Energy metric – SS-SPST-E Round 1 1.542 0.05 Round 2 0.05 0.05 0.657 4.101 Round 3 1.55 0.05 0.05 Round 4 Round 5 0.05 0.05 • Stabilization time = 5 rounds • Energy consumed / bit = 3.29 micro J

25. Summary

26. Simulation Environment • Simulator - NS-2 • Simulation area - 750 x 750 • Simulation time - 1800 seconds • # nodes - 50 • Traffic rate – 64 Kbps • # group nodes - 20

27. Performance Metrics • Packet delivery ratio • #pkts received/#pkts transmitted • Energy consumed per packet delivered • Total energy consumption/pkts received • End-to-end delay • Total delay per packet/#received nodes • Unavailability ratio • Service interrupt time/simulation time

28. Energy Spent – Different cost metrics

29. Packet Delivery Ratio – Different cost metrics

30. Unavailability Ratio – Different cost metrics

31. Packet Delivery Ratio – Different protocols

32. Energy Spent – Different protocols

33. Control Byte Overhead – Different protocols

34. Delay – Different protocols

35. Implementation • To check the correctness of the protocols • Implementation testing with 3 laptops working in ad hoc mode • Emulation – mobility, energy and bit error rate

36. Implementation Utility Classes SS-SPST Event Handler Packet Handler Packet Listener Send Receive

37. Conclusion & Future work • Energy saving using proposed cost metric • Cost of saving energy • Nodes operating in sleep mode • Testing real implementation with many nodes

38. Questions? Thank you!