1. Prolonging the Lifetime of Wireless Sensor Networks via Unequal Clustering Stanislava Soro Wendi B. Heinzelman University of Rochester IPDPS 2005

2. Outline Introduction Network Model Theoretical Analysis Simulations Conclusions

3. Introduction Important issues in WSN Energy Network lifetime Cluster Enables the efficient utilization of the limited energy resources of the deployed sensor nodes

4. Introduction Equal Cluster Size While in multi-hop communication, the nodes closest to the base station are burdened with a heavy relay traffic load and die first Network partition Motivation Maintain more uniform energy consumption among the cluster heads, so that the total energy dissipated for every cluster head is similar

5. Environment N sensor nodes A smaller number of more powerful Nodes are deployed to serve as C.H. Nodes with pre-determined locations

6. Network Model Data aggregation Perfect aggregation Nonperfect aggregation The position of cluster heads The energy consumed in each cluster of each layer

7. Network Model --aggregation Perfect aggregation Cluster head compresses all the data received from its cluster into one outgoing packet Nonperfect aggregation Cluster head sends more than one outgoing packet toward the base station

8. Network Model --cluster header Overall energy consumption of nodes that belong the C.H. Keep the energy within in the C.H. as small as possible

9. Network Model --energy consumption P: p-bit packet e1,e2 : Transmission/Amplifier e3: aggregation consume Ni: sensor in cluster i

10. Theoretical analysis Present the evaluation of the energy consumption for two clustered models Equal Clustering Size (ECS) Unequal Clustering Size (UCS) Compare the total energy consumed between ECS and UCS models, if the network is dimensioned to last at least T rounds

11. ECS For ECS, the radius of each layer is : Energy spent of C.H. in layer 1 : Energy spent of C.H. in layer 2

12. ECS The battery of sensor nodes The furthest node from its cluster head Every node has to be equipped

13. UCS Energy spent of cluster header Sensor node has to be equipped

14. Simulation Simulator : MATLAB Ra: 200 m Deploy node :400 nodes R1: Ra[0.2, 0.9]

15. Simulation Ratio of the total energy spent on batteries for the entire network for UCS and ECS Every cluster head sends 1 aggregated packet.

16. Simulation Ratio of the total energy spent on batteries for the entire network for UCS and ECS The cluster heads perform aggregation with efficiency α = 0.1.

17. Simulation Ratio of the total energy spent on batteries for the entire network for UCS and ECS The cluster heads perform aggregation with efficiency α = 1.

18. Simulation Maximum number of rounds for UCS and ECS.

19. Simulation The ratio of average number of nodes in clusters in layer 1 and 2.

20. Simulation Consider 3 layers of clusters around the base station The ratio of the number of nodes in clusters of layer 1 and 2, and ratio of layer 2 and 3 is approximately equal to 1

21. Conclusions We analyze an approach for the hierarchical organization of wireless sensor networks where, in order to balance the energy consumption of cluster head nodes, unequal size clusters are formed