daisuke.takeda@toshiba.co.jp noritaka.deguchi@toshiba.co.jp Month 2000 The sensitivity of performance to antenna element spacing when using the 802.11n Channel Model daisuke.takeda@toshiba.co.jp noritaka.deguchi@toshiba.co.jp Corporate Research & Development Center Toshiba Corporation Toshiba Corporation

Objective 802.11n channel model Month 2000 Objective 802.11n channel model Uniform linear array is mentioned in doc-940r1. D=2pd / l ( d: Antenna spacing, l: Wavelength ) In doc-940r1, angular spread is defined for each channel model. The minimum AS is less than 15 degree (Model B, 1st-cluster). The maximum AS is more than 50 degree (Model F, 2nd-cluster). Matlab channel model assumes 0.5l as typical example. (1) Toshiba Corporation

Objective (cont’d) Small AS case Large AS case Spatial Correlation Month 2000 Objective (cont’d) d d Small AS case Antenna distance is critical issue. (especially when antenna spacing d is small) Large AS case Antenna distance is not so critical. Spatial Correlation Spatial correlation is governed by Bessel Function. AS affects spatial correlation. (may not be pure Bessel Function) r J0(2p d /l) d How much does antenna spacing affect PER performance? Toshiba Corporation

Simulation Parameters Month 2000 Simulation Parameters Table 1 Simulation Parameters Data Rate (per antenna) 6Mbps, 54Mbps Number of Antenna 2x2, 3x3, 4x4 Antenna Shape Linear Array Antenna Spacing (0.3, 0.5, 1, 1.5, 5) x l Algorithm MMSE-BLAST Channel Model 802.11n (B,C,D,E) Channel Estimation Ideal Synchronization Toshiba Corporation

Fig.1 Channel Model B (LOS) Month 2000 Fig.1 Channel Model B (LOS) Toshiba Corporation

Fig.2 Channel Model D (LOS) Month 2000 Fig.2 Channel Model D (LOS) Toshiba Corporation

Performance Difference from 0.5l in Model B [dB] Month 2000 Table 2 Performance Difference from 0.5l in Model B [dB] at a PER of 10-2 0dB – 2dB 2dB – 4dB > 4dB Table 3 Performance Difference from 0.5l in Model C [dB] at a PER of 10-2 Toshiba Corporation

Performance Difference from 0.5l in Model D [dB] Month 2000 Table 4 Performance Difference from 0.5l in Model D [dB] at a PER of 10-2 0dB – 2dB 2dB – 4dB > 4dB Table 5 Performance Difference from 0.5l in Model E [dB] at a PER of 10-2 --- We have not got yet Toshiba Corporation

From Simulation Results Month 2000 From Simulation Results The performance difference is serious for Model B. Due to Narrow AS. The performance difference for 0.5l and 1.0l spacing is 6dB at a PER of 10-2. ( 54Mbps, 3x3 case ). Performance differences increase with the number of antennas. The difference increases with data rate. (54Mbps experiences large differences). In 54Mbps, Throughput performance will be seriously affected. Toshiba Corporation

Conclusions Performance varies appreciably with antenna spacing. Month 2000 Conclusions Performance varies appreciably with antenna spacing. It depends on channel models, data rate and number of antennas. The difference between 0.5l and 1.0l shows 6dB. The comparison criteria must specify antenna separation. A fair comparison of proposals can only occur if the same antenna geometry and spacing are employed by everyone. Hence, these parameters should be specified in the Comparison Criteria document for both the transmitter and receiver. Toshiba Corporation

Month 2000 End Toshiba Corporation

Fig.3 Channel Model C (LOS) Month 2000 Fig.3 Channel Model C (LOS) Toshiba Corporation

Fig.4 Channel Model E (LOS) Month 2000 Fig.4 Channel Model E (LOS) Toshiba Corporation

Spatial Correlation for Model B, Tap #3 Month 2000 Spatial Correlation for Model B, Tap #3 Toshiba Corporation