802.11ac Channel Modeling

1. 802.11ac Channel Modeling Authors: Names

2. Topics • Introduction • TGn Channel Model Applicability to TGac • Conclusions & Next Steps • Questions ? Names

3. Introduction • TGn has developed a comprehensive MIMO Broadband Channel Model • TGac can re-use the TGn channel models as a baseline with some minor changes to address possiblenew technology components such as • Higher order MIMO (> 4x4) • Spatial Division Multiple Access (SDMA) with > 4 AP antennas • Distributed MIMO • Higher Bandwidth (> 40 MHz) • OFDMA - Use multiple 20 MHz channels across multiple users. Names

4. Topics • Introduction • TGn Channel Model Applicability to TGac • Conclusions & Next Steps • Questions ? Names

5. Measurement Literature • Many studies of higher order indoor MIMO measurements found in literature. Examples include: • E. Bonek Ove, “Experimental validation of analytical MIMO channel models”, Vienna University of Technology, June 2005. • Ozcelik, H.; Herdin, M.; Hofstetter, H.; Bonek, E., "A comparison of measured 8 × 8 MIMO systems with a popular stochastic channel model at 5.2 GHz," Telecommunications, 2003. ICT 2003. 10th International Conference on , vol.2, no., pp. 1542-1546 vol.2, 23 Feb.-1 March 2003 • Nielsen, J.O.; Anderson, J.B., “Indoor MIMO Channel Measurement and Modeling,” WPMC / IWS Conference, pp. 479-483, September 2005. • Qualcomm is also conducting 8x8 and 16x16 indoor channel measurements using a MIMO channel sounding system Names

6. Measurement Setup • Indoor 8x8 and 16x16 MIMO 20 MHz channel measurements at 5.17 GHz performed at Qualcomm • Used a channel sounder built from off the shelf components • A mix of LOS and NLOS locations were chosen • Two independent channel measurements at each location (STA rotated 90°) Names

7. Example Antenna Configurations Used 8 Slot Antenna Array Two V-H and two ±45° pairs λ/2 separation between slot pairs 16 Linear Dipole Antenna Array λ/2 separation between elements Names

8. Cross-Pol Antenna Array Radiation Pattern Names

9. Applicability to SDMA, Distributed MIMO & OFDMA • Measurements indicate that users separated by a few l experience uncorrelated fading. • Spatial correlation coefficients across clients in the 0-0.2 range. • We welcome additional measurement results to validate this observation. • Recommend re-using the TGn channel models with the following notes: • Distributed MIMO, OFDMA: Use independent TGn MIMO channel realizations across links. • SDMA: Use zero spatial correlations for antennas corresponding to different clients. Names

10. Changes to Bandwidth, Delay Spread & Doppler Spread Parameters • TGn channel models are valid up to 100 MHz bandwidth. • TGac systems can use TGn models if system bandwidth <= 100 MHz. • If TGac systems include non-contiguous channels with total span > 100 MHz, then channel tap spacing needs to be decreased accordingly. • Example: Need 1ns channel tap spacing to accommodate 1 GHz. Recall that TGn channel tap spacing is 10nsec. • Need wider bandwidth channel measurements to validate channel models. • Measurements in literature do not invalidate TGn Delay spread model and Doppler spread models. • Suggest preserving these parameters, unless new measurements indicate otherwise. Names

11. TGn Channel Capacity vs. Measured Capacity • 8x8 channel measurements indicate most locations have capacity CDFs that are bounded between 11n channel models B & D. • Assumed uniform linear isotropic antenna array (l/2 spacing) at AP and client. • Capacity calculation was performed as follows: • Calculate MMSE post-processing SINR at each tone, assuming 24 dB SNR per Rx antenna. • Convert SINR at each tone to capacity. • Average capacities across all tones across 20 MHz BW Each CDF curve reflects a different test location/orientation Names

12. TGn Channel Capacity vs. Measured Capacity • 16x16 channel measurements indicate most locations have capacity CDFs that are bounded between 11n channel models B & D. • Assumed uniform linear isotropic antenna array (l/2 spacing) at AP and client. • Capacity calculation was performed as follows: • Calculate MMSE post-processing SINR at each tone, assuming 24 dB SNR per Rx antenna. • Convert SINR at each tone to capacity. • Average capacities across all tones across 20 MHz BW Each CDF curve reflects a different test location/orientation Names

13. Cross-Polarized antennas • To minimize real estate and to improve LOS MIMO performance, OEMs may also use cross-polarized antennas, as shown in the below figure for 8 antennas • TGac may need to specify channel models that include dual-polarized antennas • Need to specify XPD, correlations between cross-polarized antennas etc. • Recall that TGn provided only a brief description of dual polarized antennas, but didn’t explicitly include dual pol channel models • TGac needs to agree on whether we need to include dual-pol antennas for proposal comparison /evaluation Names

14. TGn Channel Capacity vs. Measured Capacity • 8x8 cross-pol channel measurements show tightening of capacity CDF bounds across all locations and significant capacity improvement in LOS scenarios, w.r.t the linear dipole array measurements. • TGn channel models assume XPD = 3 dB and correlation between cross-pol antennas = 0. • Capacity calculation was performed as follows: • Calculate MMSE post-processing SINR at each tone, assuming 24 dB SNR per antenna. • Convert SINR at each tone to capacity. • Average capacities across all tones across 20 MHz BW Each CDF curve reflects a different test location/orientation Names

15. TGn Channel Capacity vs. Measured Capacity • 16x16 cross-pol channel measurements show tightening of capacity CDF bounds across all locations and significant capacity improvement in LOS scenarios, w.r.t the linear dipole array measurements. • TGn channel models assume XPD = 3 dB and correlation between cross-pol antennas = 0. • Capacity calculation was performed as follows: • Calculate MMSE post-processing SINR at each tone, assuming 24 dB SNR per antenna. • Convert SINR at each tone to capacity. • Average capacities across all tones across 20 MHz BW • Conclusions & Next Steps Each CDF curve reflects a different test location/orientation Names

16. Topics • Introduction • TGn Channel Model Applicability to TGac • Conclusions & Next Steps • Questions ? Names

17. Conclusions • TGac can re-use the TGn channel models as a baseline. • TGn channel models seems to accurately bound the 8x8 and 16x16 channel capacities measured in enterprise environment. • Use of cross-polarized antennas improves system performance for 8x8 and 16x16. • TGac channel models may introduce Dual Pol channel models in addition to current models. • Need to agree on XPD, antenna correlation etc. Names

18. Next Steps • Plan to submit a first-cut TGac channel model addendum document in March 2009 meeting. • Envision that the addendum and modifications thereof can be used as a supplement to TGn channel models for simulations. • We encourage participants to collaborate with us on: • Measurement results • TGac channel model addendum document. Names

19. Questions ? Names