doc.: IEEE 802.11-03/838r0
November 2003
Validation of 802.11n Channel
Models
Qinghua Li
Communications Technology Lab
Intel Corporation
November 2003
Submission
Slide 1
Qinghua Li, Intel Corporation
doc.: IEEE 802.11-03/838r0
November 2003
Outline
•
•
•
•
•
Overview of 802.11n Channel Model
Overview of Intel’s measurements
RMS delay spread
Capacity comparison
Conclusion
Submission
Slide 2
Qinghua Li, Intel Corporation
doc.: IEEE 802.11-03/838r0
November 2003
Vinko’s Model
• Developed in a special committee within IEEE 802.11 HTSG
• Extended from Medbo’s SISO models for HIPERLAN/2
• Three companies are doing validation [1—3].
Medbo’s SISO model
Cluster decomposition and angle assignment
Angular power delay profile for all taps
Integration over all angles for each tap
Correlation matrixes seen from Rx and Tx for each tap
Kronecker product of Rx and Tx correlation matrixes
Correlation matrix for channel matrix entries and for each tap
Cholesky decomposition
Generate channel matrix from i.i.d. Gaussian random variables for each tap
Submission
Slide 3
Qinghua Li, Intel Corporation
Multipath profile seen from receiver
doc.: IEEE 802.11-03/838r0
November 2003
Power angular spectrum of Rx
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0.6
0.4
0.2
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Submission
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-250
Slide 4
Qinghua Li, Intel Corporation
Multipath profile seen from transmitter
doc.: IEEE 802.11-03/838r0
November 2003
Power angular spectrum of Tx
1
0.5
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100
50
0
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-150
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Submission
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Slide 5
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Qinghua Li, Intel Corporation
doc.: IEEE 802.11-03/838r0
November 2003
Correlation matrix on transmit (receive) side
• 4x4 MIMO channel transmit and receive correlation
matrices are
 1

Rtx   tx 21
 tx 31

 tx 41
 1

Rrx   rx 21
  rx 31

  rx 41
tx12 * tx13 * tx14 *
1
tx 23 * tx 24 *
tx 32
1
tx 34 *

tx 42
tx 43
1 
 rx12 *  rx13 *  rx14 *
1
 rx 23 *  rx 24 *
 rx 32
1
 rx 34 *

 rx 42
 rx 43
1 
Correlation matrix of channel matrix entries and its approximation

R  E hh
H
 ; R 
T
tx
  Rrx 
where h = vec[ H ]
Submission
Slide 6
Qinghua Li, Intel Corporation
doc.: IEEE 802.11-03/838r0
November 2003
Channel Matrix for Each Tap
• Channel matrix H for one tap
H   Rrx 
1/ 2
 H iid  Rtx 
1/ 2
• It can be shown that
vec  H  
 R
tx

T /2
  Rrx 
1/ 2
 vec  H
iid

• The model delivers time domain channel impulse response
for each Tx/Rx antenna pair.
Access
Point
Submission
Mobile
Station
Slide 7
Qinghua Li, Intel Corporation
doc.: IEEE 802.11-03/838r0
November 2003
Intel Measurements
•
•
•
•
•
One (typical) office environment
Distance 5-25 m and RMS delay 23-79 ns
Two 4-by-4 grids of positions are on both Tx and Rx
The transmit/receive antenna steps through 16 positions.
Channels in 5.15—5.4 GHz band are captured.
4'’
4'’
Submission
Slide 8
Qinghua Li, Intel Corporation
doc.: IEEE 802.11-03/838r0
November 2003
Measurement Locations
12m
7m
9m
5m
3m
25m
14m
18m
Submission
13m
Slide 9
Qinghua Li, Intel Corporation
doc.: IEEE 802.11-03/838r0
November 2003
Pair measurement and model by delay spread
• Mean and standard deviation of RMS delay spreads in
measurements
• RMS delay spreads in Vinko’s models
–
–
–
–
Model B: 15 ns
Model C: 30 ns
Model D: 50 ns
Model E: 100 ns
residential
small office
typical office
large office
S16
S15, S17
S6
S9
S6—
seq. 15
S7—
seq. 19
S8—
seq. 20
S9—
seq. 21
S10—
seq. 22
S15—
seq. 29
S16—
seq. 30
S17—
seq. 31
S18—seq.
32
Mean of τrms
(ns)
56.5
68.2
63.4
79.2
67.3
27.4
23.6
34.1
38.5
STD of τrms
(ns)
5.6
6.2
6.4
9.1
8.0
4.9
5.5
6.1
6.2
Submission
Slide 10
Qinghua Li, Intel Corporation
doc.: IEEE 802.11-03/838r0
November 2003
Compare capacity of for 4x4 channels
• 4x4 channel with 20 MHz bandwidth and 4’’ spacing
• Capacity mean and standard deviation at SNR 15dB
• Model error is less than 9%
Model B
Mean, STD
Model C
Mean, STD
Model D
Mean, STD
Model E
Mean, STD
IID
Channel
Mean, STD
Submission
Model Capacity
(mbps)
Measured Capacity
(mbps)
Relative Error (%)
256,
315,
324,
311,
281,
305,
312,
299,
8.8,
3.4,
3.9,
4.1,
17
18
17
13
21
23
18
24
17.8
23.4
3.3
46.8
325, 4
Slide 11
Qinghua Li, Intel Corporation
doc.: IEEE 802.11-03/838r0
November 2003
Compare 1x1 and 4x4 channel capacity
• 1x1 and 4x4 measured channels with 20 MHz bandwidth
• Capacity mean at SNR 15dB
• MIMO factor is about 3.5 for model C, D, E and their
corresponding measurements
Model B
Model C
Model D
Model E
IID Channel Model
Submission
1x1 Capacity (mbps)
measured, model
4x4 Capacity (mbps)
measured, model
4x4 Cap. / 1x1 Cap.
measured, model
89,
87,
87,
86,
87
281,
305,
312,
299,
325
3.1,
3.5,
3.6,
3.5,
3.7
95
88
86
87
Slide 12
256
315
324
311
2.7
3.6
3.7
3.6
Qinghua Li, Intel Corporation
doc.: IEEE 802.11-03/838r0
November 2003
•
•
•
•
•
•
•
Conclusion
Three office models (C,D,E) match measurements.
The residential model (B) doesn’t match measurement
well.
4x4 capacity is more than 3.5 times of 1x1’s for model C,
D, E and their corresponding measurements
The capacity means of model C,D,E are greater than the
measured by about 4%.
STDs of all models are about 20% smaller than the
measured.
Means for measured channels are less than that of IID
channel by less than 8%.
Model E (large office) has smaller capacity means than
model D (typical office).
Submission
Slide 13
Qinghua Li, Intel Corporation
doc.: IEEE 802.11-03/838r0
November 2003
References
• [1] V. Erceg, et al, “Indoor MIMO WLAN Channel Models,” IEEE
Doc. No. 802.11-03/161r2, Sept. 2003.
• [2] N. Tal, “Time Variable HT MIMO Channel Measurements,” IEEE
802.11-03/515r0, July 2003.
• [3] A. Jagannatham, V. Erceg, “Indoor MIMO Wireless Channel
Measurements and Modeling at 5.25 GHz,” Document in preparation,
Sept. 2003.
Submission
Slide 14
Qinghua Li, Intel Corporation
doc.: IEEE 802.11-03/838r0
November 2003
Backup
• CDF of 1x1 and 4x4 channel capacity for model B.
1
0.9
Prob. of capacity < abscissa
0.8
0.7
0.6
0.5
0.4
0.3
0.2
i.i.d.
measured, rms 23.6ns
model B, rms 15ns
0.1
0
Submission
0
50
100
150
200
250
300
4x4 Channel Capacity (Mbps)
Slide 15
350
400
450
Qinghua Li, Intel Corporation
doc.: IEEE 802.11-03/838r0
November 2003
Backup
• CDF of 1x1 and 4x4 channel capacity for model C.
1
0.9
Prob. of capacity < abscissa
0.8
0.7
0.6
0.5
0.4
0.3
0.2
i.i.d.
measured, rms 30.8ns
model C, rms 30ns
0.1
0
Submission
0
50
100
150
200
250
4x4 Channel Capacity (Mbps)
Slide 16
300
350
400
450
Qinghua Li, Intel Corporation
doc.: IEEE 802.11-03/838r0
November 2003
Backup
• CDF of 1x1 and 4x4 channel capacity for model D.
1
0.9
Prob. of capacity < abscissa
0.8
0.7
0.6
0.5
0.4
0.3
0.2
i.i.d.
measured, rms 56.5ns
model D, rms 50ns
0.1
0
Submission
0
50
100
150
200
250
4x4 Channel Capacity (Mbps)
Slide 17
300
350
400
450
Qinghua Li, Intel Corporation
doc.: IEEE 802.11-03/838r0
November 2003
Backup
• CDF of 1x1 and 4x4 channel capacity for model E.
1
0.9
Prob. of capacity < abscissa
0.8
0.7
0.6
0.5
0.4
0.3
0.2
i.i.d.
measured, rms 79.2ns
model E, rms 100ns
0.1
0
Submission
0
50
100
150
200
250
300
4x4 Channel Capacity (Mbps)
Slide 18
350
400
450
Qinghua Li, Intel Corporation