2-Channel Option for 11g (proposal) Rishi Mohindra MAXIM Integrated Products Rishi_Mohindra@maximhq.com Rishi Mohindra, MAXIM

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 Rishi Mohindra, MAXIM

Existing 3-channels in 11g 22 MHz 25 MHz 25 MHz 21.5 MHz 3 to 6 dB FCC forbidden band FCC forbidden band 2412 MHz (#1) 2437 MHz (#6) 2462 MHz (#11) Drawbacks for 11g: Adjacent channel interference: above 11b levels for OFDM (25 MHz channel spacing) Transmit Power Reduction: up to 6 dB less OFDM transmit power at outer channels in order to be FCC compliant Rishi Mohindra, MAXIM

2-channel Scenario Improvements for 11g: 32 MHz 30 MHz 31.5 MHz FCC forbidden band FCC forbidden band 2422 MHz (#3) 2452 MHz (#9) Improvements for 11g: Adjacent channel interference at 11b levels (30 MHz channel spacing) No Transmit Power Reduction in order to be FCC compliant (11a spectral mask sufficient) Rishi Mohindra, MAXIM

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. Rishi Mohindra, MAXIM

Tighter Spectral Mask ? Drawbacks for tighter spectral mask: 2412 MHz (#1) 2437 MHz (#6) 2462 MHz (#11) FCC forbidden band 22 MHz 25 MHz 21.5 MHz -3 to -6 dB -1.5 dB Drawbacks for tighter spectral mask: All channels with reduced power: 1.5 dB for center channel 3 to 6 dB for outer channels Rishi Mohindra, MAXIM

Channel Occupancy Issue Currently “Center” channel is occupied by the first installed network 2nd network (11g based) forced to “Outer” channel, and must operate at lower power (FCC compliant) with reduced network capacity Very Low probability of 3 channels operating in same area Why penalise the 2nd network? Adopt 2-channel as an option: both networks can operate at full power (dictated by 11a EVM and spectral mask) Rishi Mohindra, MAXIM

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. Rishi Mohindra, MAXIM

APPENDIX Rishi Mohindra, MAXIM

Simulation Model Used Rapps model 2400 MHz 2400 MHz OFDM source Power Time domain Power measurement Rapps model 2400 MHz Power 2400 MHz OFDM source BW=20 MHz 2422 MHz No spectrum analyzer used avoids frequency leakage avoids errors due to Windowing Power Noise BW=1 MHz Elliptic (N=6, 0.5dB ripple BW of 1 MHz, 85 dB rejection) Rishi Mohindra, MAXIM

Results Rapps model for Transmitter: Reference Case for BPSK OFDM: 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) Rishi Mohindra, MAXIM

Effect of Increased Backoff From Psat (dB) Output Power (dBm) Power at 22MHz (dBm/MHz) Increase in backoff (dB) BPSK 4.29 19 -30.3 0 (reference) 8.3 15.7 -42.3 4 9.3 14.7 -46 5 64 QAM 7 16.8 -37 2.7 9 15 -43.4 4.7 10 14 -47.8 5.7 Rishi Mohindra, MAXIM

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 Rishi Mohindra, MAXIM

Real PA Modulated Gain In Cartesian Plane Shows: AM/AM AM/PM Memory Effects Area enclosed = memory effects Rishi Mohindra, MAXIM

2-channel impact on FCC forbidden band Distance from forbidden band increases from 22 to 32 MHz Emission level decreases by 14 dB (see spectrum next page) Effective reduction in backoff up to 7 dB (for 2:1 slope of ACPR:Backoff) Rishi Mohindra, MAXIM

Simulated Spectrum 22 MHz (fails FCC) 14 dB 31.5 MHz (passes FCC) Rishi Mohindra, MAXIM