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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. Outline. Introduction to cognitive radio in ultra wideband AIC algorithm Simulation Conclusion.
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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
Outline • Introduction to cognitive radio in ultra wideband • AIC algorithm • Simulation • Conclusion
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
Employ multi-band orthogonal frequency division multiplexing (MB-OFDM)
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
“Cognitive Radio” Task 1) Radio-scene analysis 2) Channel-state estimation and predictive modeling 3) Transmit-power control and dynamic spectrum management => feedback
Interference avoidance method • Non-rectangular windows • Active interference canceling (AIC)
turning off the interfering tones: the inter-carrier interference may limit the notch depth to 5-10 dB • AIC (active interference cancellation tones)
Over-sampling • Why over-sampling • MB-OFDM based • interference • Over-sampling rate = r
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
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
Axis explanation: • X-axis : sub-carrier index ( over-sampling ) • Y-axis: power spectrum • Input : • QPSK ( a + j*b ) • Random • Number of fft =128
Parameter: • over-sampling rate ( r ) • protect-band sub-carriers • AIC number
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
Protected spectrum 3 sub-carriers • R=2 • Turn-off
Protected spectrum 3 sub-carriers • R=2 • AIC
With using 5 tones of AIC, It reaches the best performance. • more than 5 tones, e.g. 7 tones, performance goes back.
Protected spectrum 3 sub-carriers • R=3 • Turn-off
Protected spectrum 3 sub-carriers • R=3 • AIC
With using 7 tones of AIC, It reaches the best performance. • more than 7 tones, e.g. 9 tones, performance goes back.
Protected spectrum 3 sub-carriers • R=4 • AIC
With using 9 tones of AIC, It reaches the best performance. • more than 9 tones, e.g. 11 tones, performance goes back.
Protected spectrum 3 sub-carriers AIC R=5 best in 9 tones Protected spectrum 3 sub-carriers AIC R=6 best in 9 tones
Protected spectrum 3 sub-carriers AIC R=7 best in 9 tones Protected spectrum 3 sub-carriers AIC R=8 best in 11 tones
Protected spectrum 3 sub-carriers AIC R=50 best in 11 tones Protected spectrum 3 sub-carriers AIC R=100 best in 11 tones
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