1. 1 Interplay of Spatial Reuse and SINR-determined Data Rates in CSMACA-based, Multi-hop, Multi- rate Wirless Networks Ting-Yu Lin and Jennifer C. Hou Department of Computer Science University of Illinois at Urbana-Champaign IEEE INFOCOM 2007

2. 2 Outline Introduction Network Model and Signal Propagation/Interference Model Network Capacity as A Function of Tcs, SINR and β[i] Validation of Analytic Model Conclusions

3. 3 Introduction How does the collision be avoided in CSMA-CA-based wireless network? Physical carrier sense Binary exponential back off mechanism Data rate adjustment Network throughput : 1. Transmission time 2. Spatial reuse

4. 4 Spatial reuse Tuning the carrier-sensing threshold Tcs Spatial reuse Computes the accumulated interference Tcs vs. Data rate Increase simultaneous transmissions Within carrier sense range

5. 5 Network Model and Signal Propagation/Interference Model Network Model Multi-hop Multi-rate Based on IEEE 802.11 DCF

6. 6 Network Assumption

7. 7 Virtual transmission time

8. 8 Network Capacity as A Function of Tcs, SINR and β[i]

9. 9 Attempt Probability is derived in Calí’s model Radio propagation

10. 10 Interference d pg d cs

11. 11 Interference Model 1st –tier interference nodes

12. 12 Signal Propagation SINR Model SINR of different data r i t ’ : concurrent transmitter

13. 13 SINR vs. β[i]

14. 14 Collision Zone Extra interference By simultaneous transmissions within the d cs SINR perceived at the receiver >β[i] Accumulative interference

15. 15 Revision all accumulated interference P rcv ≧ (I sim,dcz,dcs + I con,dcs,dpg +η) *β Spatial Reuse

16. 16 Numerical Results-1 Setting 500 nodes 500*500 m 2 1125 Bytes/packet D SR =50m d pg =302m dcs = 153m CW=64

17. 17 Numerical Results-2_1 200 nodes 500*500 m 2 dcs=153 m CW =64~128

18. 18 Numerical Results-2_2 62 nodes 500*500 m 2

19. 19 Numerical Results-2_3 10 nodes 500*500 m 2

20. 20 Experiments with Settings (Tcs, CW, r) Tcs : Optimal value r= 6 or 54 Number of nodes: 25 125 Field : 500*500 Single hop CBR connection (225Bytes)

21. 21 Validation of Analytic Model

22. 22 Conclusions In this paper Investigate Relation between PHY- and MAC-layer parameters Derive Analytic model about the characters of IEEE 802.11 DCF A corresponding SINR Achieve Spatial reuse Sustainable data rates