1. WWiSE Pilot Scheme Performance
January 2005
doc.: IEEE /1616r0
January 2005
WWiSE Pilot Scheme Performance
Date:
Authors:
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Allert van Zelst, Airgo Networks
Allert van Zelst, Airgo Networks

2. January 2005
doc.: IEEE /1616r0
January 2005
Abstract
The goal of this presentation is to show that the pilot scheme proposed by WWiSE outperforms the pilot scheme of a.
This is shown by comparing the performance loss due to timing, frequency offset estimation, and pilot processing of a with that of WWiSE for the same average SNR per receive antenna. Furthermore, to only consider the effect of the pilot processing, the post-processing SNRs of the pilot processing of a and WWiSE are compared.
It is concluded that the pilot scheme of WWiSE in its mandatory configuration outperforms the pilot scheme of a.
Allert van Zelst, Airgo Networks
Allert van Zelst, Airgo Networks

3. January 2005
Introduction
The goal of this presentation is to show that the pilot scheme proposed by WWiSE outperforms the pilot scheme of a.
Since the pilot scheme of a is standardized, its performance is considered acceptable. So, WWiSE has selected it as reference.
Allert van Zelst, Airgo Networks

4. January 2005
802.11a Pilot Scheme
The pilot scheme of a is Tone Symb.1 Symb.2 Symb.3 Etc
Note that above notation does not include the pseudo random sequence pn as defined in Section of IEEE Std a-1999.
Allert van Zelst, Airgo Networks

5. January 2005
WWiSE Pilot Scheme
The pilot scheme of WWiSE for the 2 transmitter (TX) 20 MHz mode is ([1]) For TX1: Tone Symb.1 Symb.2 Symb.3 Etc For TX2: Tone Symb.1 Symb.2 Symb.3 Etc
Note that above notation does not include the pseudo random sequence pn as defined in Section of IEEE Std a-1999.
Allert van Zelst, Airgo Networks

6. 802.11a PER Performance 0.7 dB January 2005 802.11a 24 Mbps mode SISO
48 data subcarriers
4 pilot tones
16-QAM
Coding rate ½
Channel Model D
1000 byte packets
Without and with TGn impairments
Pilot processing: coherent combining
Allert van Zelst, Airgo Networks

7. WWiSE PER Performance January 2005 WWiSE 54 Mbps mode
2  2 MIMO, 20 MHz
MMSE detection
54 data subcarriers
2 pilot tones
16-QAM, rate ½
Channel Model D
1000 byte packets
Without and with TGn impairments
Pilot processing: coherent combining
Performance loss compared to ideal sync.: maximal 0.5 dB
Allert van Zelst, Airgo Networks

8. Post-Processing SNR of Pilot Processing
January 2005
Post-Processing SNR of Pilot Processing
Channel Model D
Average SNR per RX antenna = 20 dB
Pilot processing: coherent combining
Note that the shapes of these curves do not depend on the average SNR per RX antenna
Allert van Zelst, Airgo Networks

9. Post-Processing SNR of Pilot Processing
January 2005
Post-Processing SNR of Pilot Processing
Channel Model B
Average SNR per RX antenna = 20 dB
Pilot processing: coherent combining
Note that the shapes of these curves do not depend on the average SNR per RX antenna
Allert van Zelst, Airgo Networks

10. January 2005
Conclusions
For a 2  2 antenna configuration (which is the minimal requirement to support the mandatory modes of WWiSE (and other proposals)), the WWiSE pilot mapping outperforms the 11a pilot mapping, while having the same tracking bandwidth.
If one decides to not fully comply with the mandatory modes by, e.g., designing a 2  1 system, the 11a pilot processing can still be outperformed when the pilot processing for the WWiSE pilot mapping is averaged over two symbols.
Allert van Zelst, Airgo Networks

11. January 2005
References
[1] IEEE / n, “WWiSE Proposal: High throughput extension to the Standard,” C. Hansen, B. Edwards, et al.
Allert van Zelst, Airgo Networks

12. January 2005
Backup Slides
Allert van Zelst, Airgo Networks

13. Post-Processing SNR of Pilot Processing
January 2005
Post-Processing SNR of Pilot Processing
Channel Model D
Average SNR per RX antenna = 0 dB
Pilot processing: coherent combining
Allert van Zelst, Airgo Networks