1. Centralized Transmission Power Scheduling in Wireless Sensor Networks Qin Wang Computer Depart., U. of Science & Technology Beijing Edward Y. Hua Wireless Network Laboratory, Cornell University

2. OPLAB @IM.NTU2 Outline  Introduction  Assumptions  RGOPC  Evaluation  Conclusion

3. OPLAB @IM.NTU3 Introduction - DTX Sink d1 d2

4. OPLAB @IM.NTU4 Introduction - MTX Sink Minimum transmission energy (MTE)

5. OPLAB @IM.NTU5 Assumptions  Network lifetime more than a fraction, e.g., 90%, of the nodes alive  Network Assumptions uniformly deployed sending data to the sink either directly or through multiple hops  transmit: sending packets generated by itself, forward: sending packets generated by others energy-constrained  power-control mechanism (transmission power is adjustable)  Radio Model Assumptions:

6. OPLAB @IM.NTU6 RGOPC - Issues  To find the global optimized power criteria (GOPC) in a squared network case and a circular network case  To integrate the GOPC into the routing protocol (RGOPC) without extra cost

7. OPLAB @IM.NTU7 GOPC - Squared

8. OPLAB @IM.NTU8 GOPC - LP of Squared > E Ti0

9. OPLAB @IM.NTU9 GOPC - Circular

10. OPLAB @IM.NTU10 GOPC - LP of Circular

11. OPLAB @IM.NTU11 Transmission Power-based Locating/Addressing  Addressing scheme  Measured by “ Power Level 1 ”  Power criterion configuration file Addressing: From sink to Z 1j, Z 1j to Z 2j, … Sink generates the GOPC by solving LP  sub-GOPC: nodes with the same n h  E low, E up to (sink, n 1, …,n h-1 )

12. OPLAB @IM.NTU12 sub-GOPC By X ij ?!

13. OPLAB @IM.NTU13 RGOPC  Setup phase protocol location information acquisition and GOPC generation  Communication phase protocol look up power criterion configuration file to find n h2  remaining energy level ( E c ) between E low, E up of n h2 transmitting RTS to subGOPC ( ) with power level P c = n h_cur – n h_next replying CTS with address and remaining energy node with maximum remaining energy is chosen transmitting data packet

14. OPLAB @IM.NTU14 sub-GOPC How to select?

15. OPLAB @IM.NTU15 Evaluation - Simulation Setting  Squared 100m×100m, sink is 40m away from the nearest node, basic hop distance d h is 10m, 100-500 sensor nodes are distributed uniformly, E Relec =0  Circular radius 100m, sink at the center, basic hop distance d h is 10m, 400-1000 nodes are distributed uniformly, E Relec =50nJ/bit  Every node generates 2000 bits of data  E Telec = 50nJ/bit, ε amp = 100 pJ / bit /m 2  40000nJ is the expired threshold

16. OPLAB @IM.NTU16 Simulation Result - Lifetime

17. OPLAB @IM.NTU17 Simulation Result - Lifetime (cont’d)

18. OPLAB @IM.NTU18 Simulation Result - Lifetime (cont’d)

19. OPLAB @IM.NTU19 Simulation Result - Network Density

20. OPLAB @IM.NTU20 Simulation Result - Network Density (cont’d)

21. OPLAB @IM.NTU21 Simulation Result - Distribution of Nodes * : alive (blue) +: expired (green)

22. OPLAB @IM.NTU22 Conclusion  Propose an energy-efficient scheme (RGOPC) that the lifetime of every node is almost the same  Simulation shows performance of RGOPC is superior density of network has no significant impact  No more overhead cost comparing with a location-based routing protocol