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Submission Greg Breit, Qualcomm, et al.
TGac Channel Model Update
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 1
Greg Breit, [email protected] Hemanth Sampath, [email protected] Sameer Vermani, [email protected] Richard Van Nee, [email protected]
Minho Cheong, [email protected] Kwak, [email protected] Don Kim, [email protected]
Jae Joon Park, [email protected] Honma, [email protected]
Takatori Yasushi, [email protected] Yongho Seok, [email protected]
Seyeong Choi, [email protected] Phillipe Chambelin, [email protected]
John Benko, [email protected] Laurent Cariou, [email protected]
VK Jones, [email protected] Allert Van Zelst, [email protected]
Lin Yang, [email protected] Kenney, [email protected]
Eldad Perahia, [email protected] Erceg, [email protected]
Note: The author list will grow to reflect those providing explicit contributions and review comments
Submission Greg Breit, Qualcomm, et al.
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., 802.11-09/0308r1), and represented in the latest Rev 3.
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 2
Submission Greg Breit, Qualcomm, et al.
General Changes
• Removal of supporting data and detailed justifications– Revs 1 and 2 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 3 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.
– Rev 3 now references 09/0569r0 and other supporting documents
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 3
Submission Greg Breit, Qualcomm, et al.
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 4
MODIFICATIONS FOR LARGE SYSTEM BANDWIDTH
Submission Greg Breit, Qualcomm, et al.
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
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 5
40log2
2W
ceiling
System Bandwidth W Channel Sampling Rate Expansion Factor
Channel Tap Spacing
W ≤ 40 MHz 1 10 ns40 MHz < W ≤ 80 MHz 2 5 ns
80 MHz < W ≤ 160 MHz 4 2.5 ns160 MHz < W ≤ 320 MHz 8 1.25 ns320 MHz < W ≤ 640 MHz 16 625 ps640 MHz < W ≤ 1.28 GHz 32 312.5 ps
Submission Greg Breit, Qualcomm, et al.
Proposed Method for Tap InterpolationFor 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 assigned to each new tap shall be determined by dB-linear interpolation of the TGn-defined PDP tap powers 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.
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 6
TGn Tap i
TGn Tap (i+1)
20ns
10ns/k = 2.5ns
10ns/k = 2.5ns
10ns/k = 2.5ns
Example for k=4
Submission Greg Breit, Qualcomm, et al.
Performance of Tap Interpolation Scheme
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
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 7
Delay Spread (ns) for Models B-F
B(K=1)
C(K=1)
D(K=2)
E(K=4)
F(K=4)
11n 0.986 1.031 2.036 4.087 3.980
11ac
1.012 1.048 1.912 3.873 4.060
Ricean K factor (linear) calculated from generated channels using the method of Greenstein et al.
Submission Greg Breit, Qualcomm, et al.
Performance of Tap Interpolation Scheme
• 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
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 8
B C D E F F (QPSK ¾)
PER=10% 0.1 0.0 0.0 0.0 0.25 0.0
PER=1% 0.1 0.2 0.05 0.1 1.0 0.5
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)
Submission Greg Breit, Qualcomm, et al.
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 9
HIGHER ORDER MIMO
Submission Greg Breit, Qualcomm, et al.
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.
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 10
Submission Greg Breit, Qualcomm, et al.
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 11
EXTENSIONS FOR MULTI-USER MIMO
Submission Greg Breit, Qualcomm, et al.
MU-MIMO Channel Model• 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 LOS tap AoD and AoA.– 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.
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 12
Submission Greg Breit, Qualcomm, et al.
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
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 13
Submission Greg Breit, Qualcomm, et al.
DOPPLER-RELATED CHANGES
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 14
Submission Greg Breit, Qualcomm, et al.
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 4.7.3 of TGn channel model document) are absent.
• New text included in channel addendum document:
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 15
TGac shall use the Doppler model specified in the TGn channel model document, with the following modifications:
• In Section 4.7.1 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 4.7.3 of [(TGn channel model doc)], shall not be included
Submission Greg Breit, Qualcomm, et al.
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 16
MODEL EXTENSIONS FOR DUAL-POLARIZED ANTENNAS
Submission Greg Breit, Qualcomm, et al.
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.
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 17
Submission Greg Breit, Qualcomm, et al.
Normalization of Channel MatricesIncorporating 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
May 2009 doc.:IEEE 802.11-09/0575r0
Slide 18
Submission Greg Breit, Qualcomm, et al.
References1. Breit, G. et al. “TGac Channel Model Addendum Supporting Material.” Doc. IEEE802.11-
09/0569r0
2. Erceg, V. et al. “TGn Channel Models.” Doc. IEEE802.11-03/940r4.
3. 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, 2002. The 13th IEEE International Symposium on , vol.2, no., pp. 587-592 vol.2, 15-18 Sept. 2002.
4. Jian-Guo Wang; Mohan, A.S.; Aubrey, T.A., "Angles-of-arrival of multipath signals in indoor environments,"Vehicular Technology Conference, 1996. 'Mobile Technology for the Human Race,’ IEEE 46th , vol.1, no., pp.155-159 vol.1, 28 Apr-1 May 1996.
5. 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, 2008. SPAWC 2008. IEEE 9th Workshop on , vol., no., pp.580-584, 6-9 July 2008
6. 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. 1999.
7. Kwak, B.-J. et al., “Measured Channel Capacity and AoD Estimation for Multi-User MIMO Scenarios.” Doc IEEE802.11-09/543r0
8. Yasushi, T. et al., “Measured Doppler Frequency in Indoor Office Environment,” Doc. IEEE802.11-09/537r0
May 2009 doc.:IEEE 802.11-09/0575r0
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