1. 802.11ac Channel Modeling Authors: Jan 19, 2009 Month Year
doc.: IEEE yy/xxxxr0
Jan 19, 2009
802.11ac Channel Modeling
Authors:
Names
John Doe, Some Company

2. Topics Introduction TGn Channel Model Applicability to TGac
Month Year
doc.: IEEE yy/xxxxr0
Jan 19, 2009
Topics
Introduction
TGn Channel Model Applicability to TGac
Questions ?
Names
John Doe, Some Company

3. Month Year
doc.: IEEE yy/xxxxr0
Jan 19, 2009
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 possible new 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
John Doe, Some Company

4. Topics Introduction TGn Channel Model Applicability to TGac
Month Year
doc.: IEEE yy/xxxxr0
Jan 19, 2009
Topics
Introduction
TGn Channel Model Applicability to TGac
Questions ?
Names
John Doe, Some Company

5. Measurement Literature
Month Year
doc.: IEEE yy/xxxxr0
Jan 19, 2009
Measurement Literature
Many published studies of higher order Indoor MIMO measurements 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, ICT th International Conference on , vol.2, no., pp vol.2, 23 Feb.-1 March 2003
Nielsen, J.O.; Anderson, J.B., “Indoor MIMO Channel Measurement and Modeling,” WPMC / IWS Conference, pp , September 2005.
Qualcomm is also conducting 8x8 and 16x16 indoor channel measurements using a MIMO channel sounding system
Names
John Doe, Some Company

6. Jan 19, 2009
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
Jan 19, 2009
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
Month Year
doc.: IEEE yy/xxxxr0
Jan 19, 2009
Cross-Pol Antenna Array Radiation Pattern
Names
John Doe, Some Company

9. Applicability to SDMA, Distributed MIMO & OFDMA
Month Year
doc.: IEEE yy/xxxxr0
Jan 19, 2009
Applicability to SDMA, Distributed MIMO & OFDMA
Measurements indicate that users separated by a few l experience uncorrelated fading.
Spatial correlation coefficients in the range.
We welcome additional measurement results to validate this observation.
Recommend using independent TGn NRx x NTx channels for links across multiple users
NTx is the number of AP antennas
NRx is the number of STA antennas.
Names
John Doe, Some Company

10. Changes to Bandwidth, Delay Spread & Doppler Spread Parameters
Month Year
doc.: IEEE yy/xxxxr0
Jan 19, 2009
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 to accommodate the total channel bandwidth span across all the used channels.
May need 1ns channel tap spacing to accommodate 1 GHz. Recall that TGn channel tap spacing is 10nsec.
Need wider bandwidth channel measurements to derive channel models for such large bandwidths.
Measurements in Literature do not invalidate TGn Delay spread model and Doppler spread models.
Suggest preserving these parameters, unless new measurements indicate otherwise.
Names
John Doe, Some Company

11. TGn Channel Capacity vs. Measured Capacity
Month Year
doc.: IEEE yy/xxxxr0
Jan 19, 2009
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
John Doe, Some Company

12. TGn Channel Capacity vs. Measured Capacity
Month Year
doc.: IEEE yy/xxxxr0
Jan 19, 2009
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
John Doe, Some Company

13. Cross-Polarized antennas
Month Year
doc.: IEEE yy/xxxxr0
Jan 19, 2009
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
John Doe, Some Company

14. TGn Channel Capacity vs. Measured Capacity
Month Year
doc.: IEEE yy/xxxxr0
Jan 19, 2009
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
John Doe, Some Company

15. TGn Channel Capacity vs. Measured Capacity
Month Year
doc.: IEEE yy/xxxxr0
Jan 19, 2009
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
Each CDF curve reflects a different test location/orientation
Names
John Doe, Some Company

16. Conclusions TGac can re-use the TGn channel models as a baseline.
Month Year
doc.: IEEE yy/xxxxr0
Jan 19, 2009
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 dramatically improves MIMO 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
John Doe, Some Company

17. Questions ? Jan 19, 2009 Month Year doc.: IEEE 802.11-yy/xxxxr0 Names
John Doe, Some Company