Proposed TGac Channel Model Revisions (for r6)

1. Proposed TGac Channel Model Revisions (for r6) Authors: Date: 2009-07-15 Greg Breit, Qualcomm Incorporated

2. Abstract Contribution IEEE 802.11-09/0308r5, “TGac Channel Model Addendum” was accepted as the baseline channel model at the May 2009 TGac meeting. This contribution proposes updates to that document reflecting recent experimental studies to resolve “TBDs” in r5 and other editorial activity. Pending approval of these changes by TGac, 09/0308r6 will supercede 09/0308r5 as the current TGac channel model. Greg Breit, Qualcomm Incorporated

3. General Editorial Changes • Appendix A added • “Generation of Pseudorandom Per-User AoA and AoD Offsets for MU-MIMO Channel Model” • Contents of IEEE 802.11-09/0680r0 • New references • Recent experimental studies • References from IEEE 802.11-09/0680r0 • Document reformatted into current IEEE template Greg Breit, Qualcomm Incorporated

4. Changes to Section 4 (Multi-User MIMO ) • Section title shortened to “Modifications to AoA and AoD for Multi-User MIMO” • Deleted phrase “with up to 16 AP Antennas” • “TBDs” for NLOS DL AoD and UL AoA diversity changed to “±180°” • Based on experimental findings presented in contributions 802.11-09/0543, 0699, and 0822 • Simplified text reads: • For each client: • Apply single random offset uniformly distributed over ±180° to the LOS tap AoA • Apply single random offset uniformly distributed over ±180° to the LOS tap AoD • Apply single random offset uniformly distributed over ±180° to the NLOS cluster AoAs • Apply single random offset uniformly distributed over ±180° to the NLOS cluster AoDs • Reference to Appendix A added Greg Breit, Qualcomm Incorporated

5. Changes to Section 5 (Doppler Model) • R5 text: • R6 text: Recent indoor channel measurements [4] indicate that the magnitude of Doppler assumed in the TGn channel model is too high. 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, may be reduced to TBD km/h. See [4] for supporting data. Recent indoor channel measurements [4, 8, 9, 10] indicate that the magnitude of Doppler assumed in the TGn channel model is too high. 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, may be reduced to 0.18 km/h. Greg Breit, Qualcomm Incorporated

6. Justification for Revision to Doppler Model • Doppler parameter refers to ambient environmental channel stirring due to human motion, etc. • AP and client are stationary • Bell-shaped Doppler spectrum centered on 0 Hz • Recent experimental studies in indoor conditions with deliberate pedestrian activity in the channel • DCN 784 (Intel) • 468-693ms median coherence time • 119-443ms 90%ile coherence time • DCN 828 (NTT) • 1.2s coherence time at 90%ile • Propose to assume 400ms channel coherence time • Conservative assumption based on measured data • Corresponds to Doppler spread (fd) of 0.83 Hz [1] • Environmental speed v0 = fdλ = 0.18 km/hr Greg Breit, Qualcomm Incorporated

7. Changes to Section 6 (Polarization Model) • Model revised to assume zero correlation for all orthogonally-polarized elements • True theoretical rho value for cross-polarized antennas • Model in r5 assumes 0.2 correlation for co-located orthogonally-polarized antennas (zero for non-colocated xpol elements) • Forcing a non-zero value (0.2) into the correlation matrix often produces matrices that are not positive definite • Matrices have negative eigenvalues • Cannot be used in the Kronecker channel model implementation • In actuality not physically realistic correlation matrices Greg Breit, Qualcomm Incorporated

8. Outstanding Item • Indoor corridor propagation model • Current text in document Introduction: • “The scope of this document is limited to extensions of the existing TGn channel model definitions (i.e., Models A-F). The introduction of a new model definition covering indoor corridor propagation is TBD.” • Formal presentation on corridor propagation model is expected from ETRI at September IEEE meeting according to IEEE 802.11-09/0823r0. Greg Breit, Qualcomm Incorporated

9. References • Erceg, V. et al., “TGn Channel Models.” Doc. IEEE802.11-03/940r4 • Breit, G. et al., “TGac Channel Model Addendum.” Doc. IEEE 802.11-09/0308r5 • Nishimori, K. et al., “Measured Doppler frequency in indoor office environment.” Doc. IEEE 802.11-09/0537r0 • Perahia, E., “Investigation into the 802.11n Doppler Model.” Doc. IEEE 802.11-09/0538r0 • Kwak, B.-J. et al., “Measured Channel Capacity and AoD Estimation for Multi-User MIMO Scenarios.” Doc. IEEE 802.11-09/0543r1 • Breit, G. et al., “Generation of Pseudorandom Per-User AoA and AoD Offsets for MU-MIMO Channel Model.” Doc. IEEE 802.11-09/0680r0. • Breit, G. et al., “Multi-User AoD Diversity Measurements.” Doc. IEEE 802.11-09/0699r5 • Perahia, E., “Channel Coherence Time.” Doc. IEEE 802.11-09/0784 • Kwak, B.J. et al., “AoD and AoA Estimation for TGac.” Doc. IEEE 802.11-09/0822r0 • Kwak, B.J. et al., “Progress Report for Corridor Channel Model for TGac.” Doc. IEEE 802.11-09/0823r0 • Yamada, W. et al., “Coherence Time Measurement in NTT Lab.” Doc. IEEE 802.11-09/0828r0 Greg Breit, Qualcomm Incorporated