Post on 21-Dec-2015
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
Introduction to cognitive radio
Spectrum utilization
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 object1) 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” Task1) 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)
AIC algorithm
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
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MIMO AIC
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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
Simulation
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
]1,1[, ba
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
160 165 170 175 180 185 190 195 200
10
20
30
40
50
60
Power spectrum of 3 -tone cancellation
150 155 160 165 170 175 180 185 190 19510
20
30
40
50
60
70
Power spectrum of 5 -tone cancellation
120 140 160 180 200 220
-20
0
20
40
60
80
100
120Power spectrum of 7 -tone cancellation
155 160 165 170 175 180 185 190 195 200
10
20
30
40
50
60
Power spectrum of 9 -tone cancellation
Protected spectrum 3 sub-carriers R=2 AIC
0 50 100 150 200 250 300-10
0
10
20
30
40
50
60Power spectrum after AIC of 3 tones
0 50 100 150 200 250 300-300
-250
-200
-150
-100
-50
0
50
100Power spectrum after AIC of 5 tones
0 50 100 150 200 250 300-350
-300
-250
-200
-150
-100
-50
0
50
100Power spectrum after AIC of 7 tones
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
240 250 260 270 280 290
10
20
30
40
50
60
70Power spectrum of 3 -tone cancellation
240 250 260 270 280 290
30
40
50
60
70
80
Power spectrum of 5 -tone cancellation
240 250 260 270 280 290
10
20
30
40
50
60
Power spectrum of 7 -tone cancellation
230 240 250 260 270 280 290
0
10
20
30
40
50
Power spectrum of 9 -tone cancellation
Protected spectrum 3 sub-carriers R=3 AIC
0 50 100 150 200 250 300 350 40015
20
25
30
35
40
45
50
55Power spectrum after AIC of 3 tones
0 50 100 150 200 250 300 350 400-30
-20
-10
0
10
20
30
40
50
60Power spectrum after AIC of 5 tones
0 50 100 150 200 250 300 350 400-300
-250
-200
-150
-100
-50
0
50
100Power spectrum after AIC of 7 tones
0 50 100 150 200 250 300 350 400-300
-250
-200
-150
-100
-50
0
50
100Power spectrum after AIC of 9 tones
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
0 100 200 300 400 500 6005
10
15
20
25
30
35
40
45
50
55Power spectrum after AIC of 3 tones
0 100 200 300 400 500 600-20
-10
0
10
20
30
40
50
60Power spectrum after AIC of 5 tones
0 100 200 300 400 500 600-80
-60
-40
-20
0
20
40
60Power spectrum after AIC of 7 tones
0 100 200 300 400 500 600-250
-200
-150
-100
-50
0
50
100Power spectrum after AIC of 9 tones
0 100 200 300 400 500 600-250
-200
-150
-100
-50
0
50
100Power spectrum after AIC of 11 tones
With using 9 tones of AIC, It reaches the best performance.
more than 9 tones, e.g. 11 tones, performance goes back.
0 100 200 300 400 500 600 700-120
-100
-80
-60
-40
-20
0
20
40
60
80Power spectrum after AIC of 9 tones
Protected spectrum 3 sub-carriersAICR=5 best in 9 tones
Protected spectrum 3 sub-carriersAICR=6 best in 9 tones
0 100 200 300 400 500 600 700 800-140
-120
-100
-80
-60
-40
-20
0
20
40
60Power spectrum after AIC of 9 tones
Protected spectrum 3 sub-carriersAICR=7 best in 9 tones
Protected spectrum 3 sub-carriersAICR=8 best in 11 tones
0 100 200 300 400 500 600 700 800 900-100
-80
-60
-40
-20
0
20
40
60Power spectrum after AIC of 9 tones
0 200 400 600 800 1000 1200-150
-100
-50
0
50
100Power spectrum after AIC of 11 tones
1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000-100
-80
-60
-40
-20
0
20
40
60
80
Power spectrum after AIC of 11 tones
Protected spectrum 3 sub-carriersAICR=100 best in 11 tones
Protected spectrum 3 sub-carriersAICR=50 best in 11 tones
4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000
-140
-120
-100
-80
-60
-40
-20
0
20
40
Power spectrum after AIC of 11 tones
#AIC 3 5 7 9 11
r 1 2 3 4 8
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
Comparison in different re-sampling rate(1/4)
R=2 R=3
0 50 100 150 200 250 300-300
-250
-200
-150
-100
-50
0
50
100Power spectrum after AIC of 5 tones
0 50 100 150 200 250 300 350 400-300
-250
-200
-150
-100
-50
0
50
100Power spectrum after AIC of 7 tones
Comparison in different re-sampling rate(2/4)
R= 4 R=5
0 100 200 300 400 500 600-250
-200
-150
-100
-50
0
50
100Power spectrum after AIC of 9 tones
0 100 200 300 400 500 600 700-120
-100
-80
-60
-40
-20
0
20
40
60
80Power spectrum after AIC of 9 tones
Comparison in different re-sampling rate(3/4)
R=6 R=7
0 100 200 300 400 500 600 700 800-140
-120
-100
-80
-60
-40
-20
0
20
40
60Power spectrum after AIC of 9 tones
0 100 200 300 400 500 600 700 800 900-100
-80
-60
-40
-20
0
20
40
60Power spectrum after AIC of 9 tones
Comparison in different re-sampling rate(4/4)
R=8
0 200 400 600 800 1000 1200-150
-100
-50
0
50
100Power spectrum after AIC of 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
0 100 200 300 400 500 600-250
-200
-150
-100
-50
0
50
100Power spectrum after AIC of 9 tones
100 150 200 250 300 350 400 450 500 550
-80
-60
-40
-20
0
20
40
60
80
100Power spectrum after AIC of 13 tones
Protected spectrum 3 sub-carriersAICR=4
Protected spectrum 5 sub-carriersAICR=4
Protected spectrum 7 sub-carriersAICR=4
Protected spectrum 9 sub-carriersAICR=4
0 100 200 300 400 500 600-100
-80
-60
-40
-20
0
20
40
60
80Power spectrum after AIC of 15 tones
150 200 250 300 350 400 450 500 550
-120
-100
-80
-60
-40
-20
0
20
40
60
Power spectrum after AIC of 19 tones
Protected spectrum 11 sub-carriersAICR=4
Protected spectrum 13 sub-carriersAICR=4
0 100 200 300 400 500 600-120
-100
-80
-60
-40
-20
0
20
40
60
80Power spectrum after AIC of 21 tones
0 100 200 300 400 500 600-100
-80
-60
-40
-20
0
20
40
60
80Power spectrum after AIC of 23 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
2Tx AIC
Protected spectrum 4 sub-carriers R=4 AIC 6 sub-carriers
Channel?
No
2Tx AIC
250 300 350 400 450
-20
0
20
40
60
80
100
120
250 300 350 400 450
-40
-20
0
20
40
60
80
100
300 350 400-60
-40
-20
0
20
40
60
300 350 400
-60
-40
-20
0
20
40
60
Conclusion
AIC 壓縮能力大約 100 ~ 130 dB AIC sub-carrier 不是越多越好，適用即可。越遠
的 sub-carrier 影響越小。
Reference
Hirohisa Yamaguchi ,“ Active Interference Cancellation Technique for MB-OFDM Cognitive Radio” 2004
Danijela Cabric, Shridhar Mubaraq Mishra, Robert W. Brodersen, “ Implementation Issues in Spectrum Sensing for Cognitive Radios”
J. Mitola III, “Cognitive radio for flexible mobile multimedia communications,” in 1999 IEEE International Workshop on Mobile Multimedia Communications, 15-17 Nov. 1999, pp. 3-10.
J. Mitola III, “Cognitive radio an integrated agent architecture for software defined radio,” PHD thesis, KTH Royal Institute of Technology, Stockholm, Sweden, 2000.
Federal Communications Commission, “ Spectrum Policy Task Force ,”Rep. ET Docket no. 02-135, Nov. 2002.
Simon Haykin , “Cognitive Radio: Brain-Empowered Wireless Communications” IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL. 23, NO. 2, FEBRUARY 2005