1. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 1 2-Channel Option for 11g (proposal) Rishi Mohindra MAXIM Integrated Products Rishi_Mohindra@maximhq.com

2. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 2 Motivation for 2-channel option Adjacent channel interference –Reduce ACI to 11b level –Not have to additionally backoff Transmit level by 1.5 dB relative to 11a FCC Forbidden Band Compliance. –Not have to backoff transmit level by 3 to 6 dB over 66% of channel capacity, to be FCC compliant (see appendix) –No range or network throughput penalty Low probability of all 3 non-overlapping channels being used

3. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 3 Existing 3-channels in 11g Drawbacks for 11g: 1.Adjacent channel interference: –above 11b levels for OFDM (25 MHz channel spacing) 2.Transmit Power Reduction: –up to 6 dB less OFDM transmit power at outer channels in order to be FCC compliant 2412 MHz (#1)2437 MHz (#6)2462 MHz (#11) FCC forbidden band FCC forbidden band 22 MHz25 MHz 21.5 MHz 3 to 6 dB

4. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 4 2-channel Scenario 2422 MHz (#3)2452 MHz (#9) FCC forbidden band FCC forbidden band 32 MHz30 MHz31.5 MHz Improvements for 11g: –Adjacent channel interference below 11b levels (10 dB ACR improvement with 30 MHz channel spacing) –No Transmit Power Reduction in order to be FCC compliant (11a spectral mask sufficient)

5. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 5 Tighter Spectral Mask Issue Proposed in 11-02-3471r1-G- Spectral_Control_Issues_for_TGg 1.5 dB penalty in Transmit Power for middle channel (BPSK, QPSK, 16QAM) Not relevant over 66% of channel capacity (two “Outer Channels”) as they already require 3 to 6 dB additional Transmit power backoff to be FCC compliant.

6. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 6 Tighter Spectral Mask ? Drawbacks for tighter spectral mask:  All channels with reduced power: 1.5 dB for center channel 3 to 6 dB for outer channels Degrades network throughput at all channels 2412 MHz (#1)2437 MHz (#6)2462 MHz (#11) FCC forbidden band FCC forbidden band 22 MHz25 MHz 21.5 MHz -3 to -6 dB -1.5 dB

7. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 7 Channel Occupancy Issue Currently “Center” channel is occupied by the first installed network 2 nd network (11g based) forced to “Outer” channel, and must operate at lower power (to be FCC compliant) with reduced network capacity leading to more expensive deployment (more # Aps) Very Low probability of 3 channels operating in same area Why penalize the 2 nd network? Adopt 2-channel as an option: both networks can operate at full power (dictated by 11a EVM and spectral mask)

8. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 8 Proposal to instruct editor Add the following text (shown underlined): 19.4.3.8.2 Operating Channel Frequencies Operating channel frequencies of 2422 MHz and 2452 MHz (channels 3 and 9) are preferred in order to a) maximize transmit power while being FCC compliant, and b) to reduce adjacent channel interference.

9. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 9 APPENDIX

10. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 10 Simulation Model Used 2400 MHz OFDM source Power Rapps model 2400 MHz 2422 MHz BW=20 MHz Noise BW=1 MHz Elliptic (N=6, 0.5dB ripple BW of 1 MHz, 85 dB rejection) Time domain Power measurement No spectrum analyzer used avoids frequency leakage avoids errors due to Windowing

11. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 11 Results Rapps model for Transmitter:  P = 2.3, Psaturation = 24.2 dBm Reference Case for BPSK OFDM:  Backoff = 4.29 dB  Output power = 19 dBm  Power at 22 MHz = -30.3 dBm/MHz (fails FCC) Reference Case for 64QAM OFDM:  Backoff = 7 dB  EVM = -25 dB  Output power = 16.8 dBm  Power at 22 MHz = -37 dBm/MHz (fails FCC)

12. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 12 Effect of Increased Backoff Backoff From Psat (dB) Output Power (dBm) Power at 22MHz (dBm/MHz) Increase in backoff (dB) BPSK4.2919-30.30 (reference) 8.315.7-42.34 9.314.7-465 64 QAM 716.8-372.7 915-43.44.7 1014-47.85.7

13. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 13 Real RF Power Amplifier Why is measured power at 22 MHz offset more than simulation results ? Rapps model is only AM/AM distortion –It does not model AM/PM distortion –It does not model MEMORY effects

14. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 14 Real PA Shows: a)AM/AM b)AM/PM c)Memory Effects AM/AM AM/PM Area enclosed = memory effects Gain Variation in Cartesian Plane Ref: Circuit & System Cosimulation for Transmitter Linearization, by Rishi Mohindra, Wireless Symposium Spring 1999 Conference

15. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 15 2-channel impact on FCC forbidden band Distance of forbidden band increases from 22 to 32 MHz Emission level decreases by 14 dB (see next page) No additional backoff from what is required for 11a spectral mask

16. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 16 Simulated Spectrum 22 MHz (fails FCC) 31.5 MHz (passes FCC) 14 dB

17. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 17 2-channel impact on Adjacent Channel Interference Channel spacing increases from 25 to 30 MHz Adjacent Channel Interference reduces by 10 dB (see next page), and is below 11b levels

18. July 2002doc.: IEEE 802.11-02/420r0 Submission Rishi Mohindra, MAXIMSlide 18 Adjacent Channel Ratio 10 dB 5 MHz