1. doc.: IEEE 802.11-02/180r0 Submission March 2002 Monisha Ghosh, et al., Philips Slide 1 On The Use Of Multiple Antennae For 802.11 Monisha Ghosh, Xuemei Ouyang, Guido Dolmans Philips Research.

2. doc.: IEEE 802.11-02/180r0 Submission March 2002 Monisha Ghosh, et al., Philips Slide 2 Goal Of Next Generation WLANS? Increased robustness. (-> fewer errors -> less retransmission -> higher throughput) Increased data rate in terms of raw Mbps. Backward compatibility through headers.

3. doc.: IEEE 802.11-02/180r0 Submission March 2002 Monisha Ghosh, et al., Philips Slide 3 Exploiting Channel Diversity Frequency diversity: Bit interleaved coded modulation. Space diversity: Multiple antennae. Question: In an indoor situation, is there sufficient diversity among closely spaced antennae? Answer: Preliminary measurements in 5 gHz indicate that there is.

4. doc.: IEEE 802.11-02/180r0 Submission March 2002 Monisha Ghosh, et al., Philips Slide 4 Channel Measurements At 5gHz

5. doc.: IEEE 802.11-02/180r0 Submission March 2002 Monisha Ghosh, et al., Philips Slide 5 Multiple Antennae Well studied topic for the last few years. OFDM is very well suited for use with multiple antennae. (802.16 has an optional mode using multiple antennae.) Many (all?) 802.11 receivers already have 2 antennae, using switched diversity. Additional component required for exploiting full diversity is an additional RF front-end. Recent advances in RF technology will make this cost effective in the near future.

6. doc.: IEEE 802.11-02/180r0 Submission March 2002 Monisha Ghosh, et al., Philips Slide 6 Higher (> 100 Mbps) Data Rate Options For 802.11 Larger Constellation: 54Mbps already uses 64 QAM. Can a wireless system support a larger constellation? Turbo-coding: Requires at least 3 or 4 iterations for good performance. Double bandwidth: Inefficient use of bandwidth. Multiple antenna: Cost is in the additional antenna and RF front end, the DSP does not add much complexity to existing receivers.

7. doc.: IEEE 802.11-02/180r0 Submission March 2002 Monisha Ghosh, et al., Philips Slide 7 Possible Configurations For 2x2 system 1 Tx/2 Rx: same data rate, increased robustness, backward compatible. 2 Tx/1 Rx, space-time coded (e.g. Alamouti): same data rate, increased robustness, backward compatiblity through header. 2 Tx/2Rx, space-time coded: same data rate, increased robustness, backward compatibility through header. 2 Tx/2 Rx, MIMO: Increased data rate and robustness.

8. doc.: IEEE 802.11-02/180r0 Submission March 2002 Monisha Ghosh, et al., Philips Slide 8 1 Tx, 2 Rx System Performance

9. doc.: IEEE 802.11-02/180r0 Submission March 2002 Monisha Ghosh, et al., Philips Slide 9 2 Tx, 1 Rx System Performance

10. doc.: IEEE 802.11-02/180r0 Submission March 2002 Monisha Ghosh, et al., Philips Slide 10 2 Antennae At AP

11. doc.: IEEE 802.11-02/180r0 Submission March 2002 Monisha Ghosh, et al., Philips Slide 11 2 Tx/2 Rx MIMO Performance

12. doc.: IEEE 802.11-02/180r0 Submission March 2002 Monisha Ghosh, et al., Philips Slide 12 2 Antennae At AP, 1 Antenna At Mobile Use transmit diversity from AP to mobile: would require a change to allow for Alamouti encoding. Gives 2 to 4 dB gain over 1 Tx/1 Rx. Use receive diversity for mobile to AP. Gives 4 to 6 dB over 1 Tx/1 Rx. Simple way to increase robustness for all mobiles by the addition of a single extra antenna and RF unit at the AP.

13. doc.: IEEE 802.11-02/180r0 Submission March 2002 Monisha Ghosh, et al., Philips Slide 13 Conclusions A simple 2 x 2 antennae system can improve both robustness and bit-rate. Various options possible, depending on level of complexity desired. Backward compatibility easily maintained through header.