Analysis of Active Interference Cancellation for Cognitive Radio MB-OFDM UWB

1. Analysis of Active Interference Cancellation for Cognitive Radio MB-OFDM UWB Speaker: 王貞傑 Professor: 吳仁銘教授 date: 2007. 06. 01

2. Outline • Introduction to cognitive radio in ultra wideband • AIC algorithm • Simulation • Conclusion

3. Introduction to cognitive radio

4. Spectrum utilization

5. Resource :spectrum • UWB : 3.1-10.6 GHz Wimax : 3.3-3.8 GHz ,5.4-5.825 GHz IEEE802.11a : 4.9 -5.85 GHz

6. Employ multi-band orthogonal frequency division multiplexing (MB-OFDM)

7. Cognitive Radio object 1) highly reliable communication 2) efficient utilization of the radio spectrum • “Cognitive Radio” does what? 1) sense the spectral environment over a wide available band 2) use the spectrum only if communication does not interfere with licensed user. multiple signal dimensions :time, frequency, physical space, and user networks

8. “Cognitive Radio” Task 1) Radio-scene analysis 2) Channel-state estimation and predictive modeling 3) Transmit-power control and dynamic spectrum management => feedback

9. Interference avoidance method • Non-rectangular windows • Active interference canceling (AIC)

10. AIC algorithm

11. turning off the interfering tones: the inter-carrier interference may limit the notch depth to 5-10 dB • AIC (active interference cancellation tones)

12. Over-sampling • Why over-sampling • MB-OFDM based • interference • Over-sampling rate = r

15. Minimization

16. MIMO AIC

18. Minimization

24. 唯一解:利用錯開頻帶，來消除所要干擾主要頻帶的訊號，頻帶間不重複利用，否則det =0 • 頻帶間有重複(overlap)，則造成有無限多組解

25. Simulation

26. Picture parameter • Axis explanation & Input • Parameter • re-sampling rate Vs AIC number • Turn-off Vs AIC with different re-sampling rate • Comparison in different re-sampling rate • Different protected sub-carriers • MIMO AIC

27. Axis explanation: • X-axis : sub-carrier index ( over-sampling ) • Y-axis: power spectrum • Input : • QPSK ( a + j*b ) • Random • Number of fft =128

28. Parameter: • over-sampling rate ( r ) • protect-band sub-carriers • AIC number

29. Picture parameter • Axis explanation & Input • Parameter • re-sampling rate Vs AIC number • Turn-off Vs AIC with different re-sampling rate • Comparison in different re-sampling rate • Different protected sub-carriers • MIMO AIC

30. Protected spectrum 3 sub-carriers • R=2 • Turn-off

32. Protected spectrum 3 sub-carriers • R=2 • AIC

34. With using 5 tones of AIC, It reaches the best performance. • more than 5 tones, e.g. 7 tones, performance goes back.

35. Protected spectrum 3 sub-carriers • R=3 • Turn-off

37. Protected spectrum 3 sub-carriers • R=3 • AIC

39. With using 7 tones of AIC, It reaches the best performance. • more than 7 tones, e.g. 9 tones, performance goes back.

40. Protected spectrum 3 sub-carriers • R=4 • AIC

42. With using 9 tones of AIC, It reaches the best performance. • more than 9 tones, e.g. 11 tones, performance goes back.

43. Protected spectrum 3 sub-carriers AIC R=5 best in 9 tones Protected spectrum 3 sub-carriers AIC R=6 best in 9 tones

44. Protected spectrum 3 sub-carriers AIC R=7 best in 9 tones Protected spectrum 3 sub-carriers AIC R=8 best in 11 tones

45. Protected spectrum 3 sub-carriers AIC R=50 best in 11 tones Protected spectrum 3 sub-carriers AIC R=100 best in 11 tones

47. Picture parameter • Axis explanation & Input • Parameter • re-sampling rate Vs AIC number • Turn-off Vs AIC with different re-sampling rate • Comparison in different re-sampling rate • Different protected sub-carriers • MIMO AIC

48. Comparison in different re-sampling rate(1/4) R=2 R=3

49. Comparison in different re-sampling rate(2/4) R= 4 R=5

50. Comparison in different re-sampling rate(3/4) R=6 R=7