1. TGac Channel Model Update
Month Year
doc.: IEEE yy/xxxxr0
May doc.:IEEE /0575r1
TGac Channel Model Update
Greg Breit,
Hemanth Sampath,
Sameer Vermani,
Richard Van Nee,
Minho Cheong,
Byung-Jae
Myung Don Kim,
Jae Joon Park,
Naoki Honma,
Takatori Yasushi,
Yongho Seok,
Seyeong Choi,
Phillipe Chambelin,
John Benko,
Laurent Cariou,
VK Jones,
Allert Van Zelst,
Lin Yang,
Thomas Kenney,
Eldad Perahia,
Vinko Erceg,
Note: The author list will grow to reflect those providing explicit contributions and review comments
John Doe, Some Company

2. Month Year
doc.: IEEE yy/xxxxr0
May doc.:IEEE /0575r1
Introduction
The TGn task group has developed a comprehensive MIMO broadband channel models, with support for 40 MHz channelization and 4 antennas.
The TGac task group is targeting > 1 Gbps MAC SAP throughput using one or more of the following technologies:
Higher order MIMO (> 4x4)
Higher Bandwidth (> 40 MHz)
Multi-User MIMO with > 4 AP antennas
OFDMA
This contribution summarizes followup work since the March 2009 presentation of the draft TGac channel model addendum document (Breit et al., /0308r1), and represented in the latest Rev 4.
John Doe, Some Company

3. General Changes Removal of supporting data and detailed justifications
May doc.:IEEE /0575r1
General Changes
Removal of supporting data and detailed justifications
Earlier revs of 09/0308 contained large amounts of supporting simulation and measurement data as well as justification text for the various proposed channel model extensions
Rev 4 has been pared down to a direct statement of the model extensions
Supporting data and detailed justification text for 09/0308 are now contained in new contribution 09/0569r0.
09/0308r4 now references 09/0569r0 and other supporting documents

4. Modifications FOR Large System Bandwidth
May doc.:IEEE /0575r1
Modifications FOR Large System Bandwidth

5. Modifications For Large System BW
Month Year
doc.: IEEE yy/xxxxr0
May doc.:IEEE /0575r1
Modifications For Large System BW
TGn channel model addressed up to 40 MHz system bandwidth, assuming tap-spacing of 10 nsec.
For TGac systems with larger overall system bandwidth (W), we propose to decrease channel tap spacing by a factor of
Tap spacing reduction is accomplished by linear interpolation of the TGn-defined channel tap powers on a cluster-by-cluster basis
System Bandwidth W
Channel Sampling Rate Expansion Factor
Channel Tap Spacing
W ≤ 40 MHz 1
10 ns
40 MHz < W ≤ 80 MHz 2
5 ns
80 MHz < W ≤ 160 MHz 4
2.5 ns
160 MHz < W ≤ 320 MHz 8
1.25 ns
320 MHz < W ≤ 640 MHz 16
625 ps
640 MHz < W ≤ 1.28 GHz 32
312.5 ps
John Doe, Some Company

6. Proposed Method for Tap Interpolation
May doc.:IEEE /0575r1
Proposed Method for Tap Interpolation
For each cluster in the TGn-defined model, and assuming a channel sampling rate expansion factor k (new sampling rate = k*100MHz), a sequence of k-1 new PDP taps, spaced 10/k ns apart, shall be appended after each TGn-defined PDP tap. The first PDP tap in the sequence shall occur 10/k ns after the TGn-defined PDP tap. The power (in dB) assigned to each new tap shall be determined by linear interpolation of the TGn-defined PDP tap powers (in dB) immediately before and after the new PDP tap, in proportion to its position in time relative to the two TGn PDP taps. No new PDP taps shall be added after the final TGn PDP tap for each cluster.
Example for k=4

7. Performance of Tap Interpolation Scheme
May doc.:IEEE /0575r1
Performance of Tap Interpolation Scheme
Delay Spread (ns) for Models B-F B C D E F
11n
15.648
33.433
49.953
98.990
148.92
11ac
15.933
33.278
49.402
97.249
142.14
Ricean K factor (linear) calculated from generated channels using the method of Greenstein et al. B
(K=1) C D
(K=2) E
(K=4) F
11n
0.986
1.031
2.036
4.087
3.980
11ac
1.012
1.048
1.912
3.873
4.060

8. Performance of Tap Interpolation Scheme
May doc.:IEEE /0575r1
Performance of Tap Interpolation Scheme
Link performance comparison: 40 MHz TGn vs. 80 MHz TGac (interpolated)
1x1, 64QAM, 2/3, except last column
(Values represent dB difference in required SNR to achieve 1% and 10% PER) B C D E F
F (QPSK ¾)
PER=10%
0.1
0.0
0.25
PER=1%
0.2
0.05
1.0
0.5
Followup simulations performed for 4x4 MIMO
Same parameters as SISO simulations above
Models B and D only
PER curves agree within 0.1dB at 1% and 10% PER

9. May doc.:IEEE /0575r1
Higher Order MIMO

10. Month Year
doc.: IEEE yy/xxxxr0
May doc.:IEEE /0575r1
Higher Order MIMO
Retain the TGn Kronecker models for TGac higher order MIMO channel model.
Recent measurements and analysis [1] show that
TGn channel models, with appropriately chosen cluster AoA and AoDs tightly bound and sweep the range of MIMO performance observed in real environments.
John Doe, Some Company

11. Extensions for Multi-User MIMO
May doc.:IEEE /0575r1
Extensions for Multi-User MIMO

12. MU-MIMO Channel Model May 2009 doc.:IEEE 802.11-09/0575r1
Assume TGn-defined cluster AoDs and AoAs as baseline.
For each client in the DL:
Apply single random offset of ±180° to the LOS tap AoD and AoA.
Apply single random offset of ±180° to the NLOS cluster AoA
Apply single random offset of ±TBD° to the NLOS cluster AoD.
For each client in the UL:
Apply single random offset of ±180° to the NLOS cluster AoD
Apply single random offset of ±TBD° to the NLOS cluster AoA.
Notes:
The ±TBD° value will be updated upon completion of analysis by ETRI [7].
The random offset can be determined by any well-known algorithm [TBD].
The appendix will specify the exact algorithm and example values.

13. Advantages of MU-MIMO Model
May doc.:IEEE /0575r1
Advantages of MU-MIMO Model
Physically realistic - Introduces statistical AoA/AoD variation across clients
Minimal change to TGn channel model
Simulation complexity increase is reasonable:
TX/RX correlation matrix need to be computed only once per client, for the entire simulation run

14. Doppler-Related Changes
May doc.:IEEE /0575r1
Doppler-Related Changes

15. Doppler-Related Changes
May doc.:IEEE /0575r1
Doppler-Related Changes
New measurement results by NTT [8] indicate the following:
The TGn assumptions for main temporal Doppler component (Section 4.7.1) is too high
The fluorescent light effects (mentioned in Section of TGn channel model document) are absent.
New text included in channel addendum document:
TGac shall use the Doppler model specified in the TGn channel model document, with the following modifications:
 In Section of TGn channel model document, the environmental speed, vo, shall be reduced to TBD km/h
 The effect of fluorescent lighting, as specified in Section of [(TGn channel model doc)], shall not be included

16. Model Extensions for DUAL-POLarized ANTENNAS
May doc.:IEEE /0575r1
Model Extensions for DUAL-POLarized ANTENNAS

17. Incorporating Dual Polarized Antennas
May doc.:IEEE /0575r1
Incorporating Dual Polarized Antennas
Dual-polarized antennas are likely to be employed in TGac devices
Reduces real-estate in devices.
Improves MIMO capacity, especially in LOS channel conditions
Retain the TGn Dual-Pol channel model for TGac higher order MIMO channel model, with the following parameters:
XPD value of 10 dB for the steering matrix HF,
XPD value of 3 dB for the variable matrix Hv.
0.2 correlation for co-located orthogonally-polarized antenna elements
Zero correlation for non-co-located orthogonally-polarized antenna elements
Recent measurements and analysis [1] show that
TGn dual-pol channel models, with appropriately chosen cluster AoA and AoDs tightly bound and sweep the range of MIMO performance observed in real environments.

18. Normalization of Channel Matrices Incorporating XPD
May doc.:IEEE /0575r1
Normalization of Channel Matrices Incorporating XPD
Modeled channels incorporating XPD should be normalized only to the norm of the co-polarized elements of the channel matrix
Note: Normalization to the Frobenius norm of the entire channel matrix will fail to account for the additional path loss due to transmitting and receiving on orthogonal polarizations

19. References May 2009 doc.:IEEE 802.11-09/0575r1
Breit, G. et al. “TGac Channel Model Addendum Supporting Material.” Doc. IEEE /0569r0
Erceg, V. et al. “TGn Channel Models.” Doc. IEEE /940r4.
Schumacher, L.; Pedersen, K.I.; Mogensen, P.E., "From antenna spacings to theoretical capacities - guidelines for simulating MIMO systems," Personal, Indoor and Mobile Radio Communications, The 13th IEEE International Symposium on , vol.2, no., pp vol.2, Sept
Jian-Guo Wang; Mohan, A.S.; Aubrey, T.A., "Angles-of-arrival of multipath signals in indoor environments,"Vehicular Technology Conference, 'Mobile Technology for the Human Race,’ IEEE 46th , vol.1, no., pp vol.1, 28 Apr-1 May 1996.
Kaltenberger, F.; Kountouris, M.; Cardoso, L.; Knopp, R.; Gesbert, D., "Capacity of linear multi-user MIMO precoding schemes with measured channel data," Signal Processing Advances in Wireless Communications, SPAWC IEEE 9th Workshop on , vol., no., pp , 6-9 July 2008
L. J. Greenstein, D. G. Michelson, and V. Erceg, “Moment-method estimation of the Ricean K-factor,” IEEE Commun. Lett., vol. 3, no. 6, pp. 175–176, Jun
Kwak, B.-J. et al., “Measured Channel Capacity and AoD Estimation for Multi-User MIMO Scenarios.” Doc IEEE /543r0
Yasushi, T. et al., “Measured Doppler Frequency in Indoor Office Environment,” Doc. IEEE /537r0