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

Outline Introduction Goals System Model Cost metric Simulation & Implementation Conclusion

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

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.

Shortest Path Self-Stabilizing Protocol SS-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

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.

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

Wireless Multicast Advantage X Y Z P XZ P XY P XZ > P XY

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

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

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

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

Energy Model E Tx = E elec. K + E amp. K. d 2 E Rx = E elec. K E elec = Fixed energy E amp = Amplification energy K = Number of bits d = distance

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

R 1 2 NG X SS-SPST An Example

R 1 2 NG X Round 1 Round 2 Round 3

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

Cost metric Hop count C ij = 1 Transmission Energy C ij = T ij Transmission Energy based on farthest node C ij = (T ij + R) if j is the farthest node from i = R otherwise

Cost metric Transmission Energy based on farthest node with discard energy C ij = (T ij +R+L i ) if j is the farthest node from i = R otherwise L i = R * (#neighbors i - #tree children i )

An Example

Hop count metric – SS-SPST Stabilization time = 3 rounds Energy consumed / bit = 5.95 micro J Round 1 Round 2 Round 3

Transmission Energy metric – SS-SPST-T Stabilization time = 4 rounds Energy consumed / bit = 4.72 micro J Round 1 Round 2 Round Round 4

Max Transmission Energy metric – SS-SPST-F Stabilization time = 5 rounds Energy consumed / bit = micro J Round 1 Round 2 Round 3 Round Round

Max Transmission Energy + Discard Energy metric – SS-SPST-E Stabilization time = 5 rounds Energy consumed / bit = 3.29 micro J Round 1 Round 2 Round 3 Round Round

Summary Metric# roundsEnergy in micro J SS-SPST SS-SPST-T SS-SPST-F SS-SPST-E

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

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

Energy Spent – Different cost metrics

Packet Delivery Ratio – Different cost metrics

Unavailability Ratio – Different cost metrics

Packet Delivery Ratio – Different protocols

Energy Spent – Different protocols

Control Byte Overhead – Different protocols

Delay – Different protocols

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

Implementation Utility Classes Packet Listener Event Handler SS-SPST Packet Handler SendReceive

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

Questions? Thank you!