1. 1 Core-PC: A Class of Correlative Power Control Algorithms for Single Channel Mobile Ad Hoc Networks Jun Zhang and Brahim Bensaou The Hong Kong University of Science and Technology TWC 07

2. Outline Introduction Correlative Power Constraints Core-PC Performance Evaluation Conclusion

3. Introduction The energy supply in wireless devices is limited by their battery capacity. From measurements in real systems, – Packet processing only consumes a small fraction – The energy is consumed by the transmission reception listening to the channels

4. Introduction It is important to design power control algorithms that – Improving network throughput – Reducing energy consumption

5. Goal To design power controlled MAC protocols – Throughput better than IEEE 802.11 – Energy consumption smaller than IEEE 802.11

6. Introduction All previous works on power control only consider the assignment of the transmission power of each frame separately.

7. Introduction The authors derive a set of equations that correlate the transmission powers of RTS, CTS, DATA and ACK frames. The authors derive a class of adaptive power control algorithms (Core-PC).

8. Correlative Power Constraints -- Basic Framework and Definitions The transmission zone – The received power level of a frame from node i in its transmission zone is higher than or equal to κ. The carrier sensing zone – The received power level of a frame from node i in its carrier sensing zone is higher than or equal to η.

9. Correlative Power Constraints -- Noise Level Estimation When node A is receiving the CTS reply from a node B, we assume – The channel at node A is idle. – The node’s NAV is always set and the node is silenced whenever it is in the transmission zone. – The thermal noise level is negligible. – The propagation model is the two ray ground propagation model. Path loss

10. Correlative Power Constraints -- Noise Level Estimation R avg : average transmission range P avg : average transmission power Δ : the density of simultaneous transmitters outside A’s transmission zone Δ is upper bounded by

11. Correlative Power Constraints -- Noise Level Estimation According to the two ray ground propagation model

12. Correlative Power Constraints -- Requirements on Power Assignment for Frame Reception The received power of RTS from node A to node B at location B The received power of the CTS at node A must also fulfill the SIR requirement. SIR threshold The transmission power of CTS from node B to node A AB RTS CTS

13. Correlative Power Constraints -- Requirements on Power Assignment for Frame Reception AB

14. To simplify the notation,

15. Correlative Power Constraints -- Requirements on Power Assignment for Frame Reception

16. Correlative Power Constraints -- Feasibility of Power Assignment

17. The minimal possible power assignment for a DATA frame in a successful 4-way handshake is

18. Core-PC

19. In Algorithm 1, different combination of (P RTS,P avg ) lead to different power assignment algorithms.

20. Core-PC Three alternative approaches may be adopted for setting the P RTS. – (a) Simple scenario P RTS =P max – (b) Symmetric scenario P RTS =P CTS – (c) Minimum power scenario The RTS frame is transmitted at a power level such that the DATA transmission power is minimized.

21. Core-PC Similarly, there are different ways of choosing the value of P avg. – (A) Worst case scenario P avg =P max – (B) Node-related adaptive scenario (i) initially P avg =P max (ii) all other nodes transmit their DATA frame at the same power level – (C) Network-related adaptive scenario P avg =0.9P avg +0.1P t transmission power of a captured frame

22. Core-PC (a)(A)(b)(A)(c)(A)

23. Core-PC

24. Performance Evaluation Simulator: NS-2 Routes: AODV Data rate: 11Mbps κ: 3.652e-10 Watts η: 1.559e-11 Watts ζ: 10dB P max : 0.2818 Watts R max : 250m

25. Performance Evaluation -- Single Hop Scenario 50m (I) 200m (II) 150m CBR traffic is generated and carried in UDP datagrams with a packet size of 512 bytes Two packet sending rate: – 200 packets/s per sender – 400 packets/s per sender

26. Performance Evaluation -- Single Hop Scenario Rate = 200 PKT/SECEND200m

27. Performance Evaluation -- Single Hop Scenario Rate = 400 PKT/SECEND200m

28. Performance Evaluation -- Single Hop Scenario Rate = 400 PKT/SECEND150m

29. Performance Evaluation -- Multi-Hop Static Scenario 49 nodes 400*400 m 2 area 7 flows are set between randomly chosen end-to-end source-destination pairs Packet size is 512 bytes

30. Performance Evaluation -- Multi-Hop Static Scenario

32. Performance Evaluation -- Multi-Hop Scenario With Mobility 5 m/s

33. Performance Evaluation -- Multi-Hop Scenario With Mobility

34. Conclusion The correlations among the required transmission power of RTS/CTS/DATA/ACK – derived constraints that ensure the correct delivery Using these constraints – The authors developed a class of correlative power control algorithms Simulations have shown the algorithm achieves – Higher throughput – Lesser energy consumption

35. Thank you