1. An Application-Specific Protocol Architecture for Wireless Microsensor Networks Wendi Rabiner Heinzelman, Anantha Chandrakasan, and Hari Balakrishnan (MIT) IEEE Transactions on Wireless Communications 2002 Bao-Hua Yang

2. Outline  Introduction  LEACH  LEACH-C  Simulation  Conclusion

3. Introduction  Sensor network Contain hundreds of cheap sensor nodes Monitor a remote/dangerous environment Sensor nodes  Limited energy

4. Introduction  Use the following metrics to evaluate the sensor network protocol Ease of deployment System lifetime Latency Quality

5. Introduction  Network model Base station: fixed, far away from the nodes Sensor node  Homogeneous, energy-constrained  one-hop from B.S  location information: GPS  Nodes located close to each other have correlated data

6. LEACH  LEACH (Low-Energy Adaptive Clustering Hierarchy)  Key feature of LEACH Distributed Randomized rotation of cluster head Local data fusion

7. LEACH BS

8. LEACH  Set-up phase Cluster formation  Steady-state phase Data transmission Time START Set-up Frame Round Steady-state

9. LEACH  Set-up phase Cluster head  Each node itself decides whether or not become a cluster head for current round  Using CSMA broadcast “ cluster-head-advertisement ” Other sensor nodes  Transmit a join-request message back to the chosen cluster head Cluster head broadcast TDMA schedule

10. LEACH P: the percentage of cluster heads G: the nodes that have not been cluster heads in the last 1/p rounds If p=0.05, N=100 r=0, T(n)=5%=0.05 r=1, T(n)=5%/95%=0.0526 r=2, T(n)=5%/90%=0.0556 …

11. LEACH  Steady-state phase Node i transmits once per frame Radio can be turn off until its slot Cluster formed175362 4 175362 4 Set-upSteady-state slot frame Time

12. LEACH-C  Main idea Set-up phase  A centralized algorithm to form cluster Steady-state phase  The same with LEACH

13. LEACH-C Time START Set-up Frame Round Steady-state 1.Each node send location and energy level to BS 2.BS using the simulated annealing algorithm to find K optimal clusters

14. Simulation  Compare Minimum Transmission Energy (MTE) Static cluster LEACH LEACH-C

15. Simulation Number of data signals received at the base station over time

16. Simulation Number of data signals received at the base station for a given amount of energy

17. Simulation

19. Conclusion  This paper develop LEACH and LEACH-C protocol to achieve good performance in terms of System lifetime latency