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This document explores the impact of non-contiguous channel spectrum on the performance of 802.11ac power amplifiers (PAs), specifically focusing on EVM requirements, low EVM and DEVM floors, efficiency, and gain flatness.
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80-MHz Non-Contiguous Channel Spectrum Authors: Date: 2011-01-17 Tian-Wei Huang, NTU and Peter Gammel, SiGe
802.11ac SiGe Roadmap Present Status Following IEEE standards on TX requirements No clear requirement on PAPR (channel out phasing proposed) Spectral flatness and Mask spec not finalized (+4, -6dB flatness to roll off edge subcarriers will improve spectral regrowth) Will there be need for non-contiguous channels? Performing spectral measurements on impact of wider modulation Evaluating 5GHz PA for improved EVM floor (estimating EVM requirement <2% max) 2011 Plan Purchase Test Equipment as soon as available for EVM and Signal Generation. Look at improved PA biasing schemes to improve linearity and EVM for the higher rate modes. Provide first samples of optimized 11ac 5GHz PA in SiGe. January 2011 Tian-Wei Huang, NTU and Peter Gammel, SiGe
802.11ac Impact to PA performance Expect EVM requirement ~1% Impact of low EVM and DEVM floor over V and T Efficiency impact due to increased backoff Gain Flatness across channel concerns Band Edge impact January 2011 Tian-Wei Huang, NTU and Peter Gammel, SiGe
Proposed VHT 20/40/80/160 Spectral Flatness Noncontiguous 160 MHz devices may transmit a contiguous 160 MHz waveform by placing its two 80 MHz segments adjacent to each other. It would be difficult for such transmissions to meet the +4/-4 dB requirement near the center of the contiguous 160 MHz waveform Two non-contiguous 80MHz transmissions shall use the 80MHz mask in each 80MHz transmission January 2011 • doc.: IEEE 802.11-10/1109r1 September 2010 - Proposed relaxation to spectral flatness spec to improve Band Edge and Spectral Mask Slide 4 Tian-Wei Huang, NTU and Peter Gammel, SiGe
Proposed VHT 20/40/80/160MHz Mask January 2011 • doc.: IEEE 802.11-10/1109r1 September 2010 - Proposed Spectral Mask requirement (relaxed over 11n) Slide 5 Tian-Wei Huang, NTU and Peter Gammel, SiGe
80 MHz Channelization • Propose to follow the same approach as in 40 MHz • Consists of two adjacent IEEE 40 MHz channels • Do not partially overlap with each other • Justification • Not necessary to come up with coexistence rules for partially overlapping channels • Sufficient number of 80 MHz channels • 5 non-overlapping 80 MHz channels in US • 4 non-overlapping 80 MHz channels in Europe January 2011 July 2010 • doc.: IEEE 802.11-10/0773r0 5170 MHz 5330 MHz 5490 MHz 5710 MHz 5735 MHz 5835 MHz 36 40 44 48 52 56 60 64 100 104 108 112 116 120 124 128 132 136 140 149 153 157 161 165 IEEE channel # 20 MHz 40 MHz Proposed 80 MHz channels for US Youhan Kim, et al. Slide 6 Tian-Wei Huang, NTU and Peter Gammel, SiGe
80MHz Mask measured with 2xHT40 signals January 2011 Mask1 Mask2 Mask3 Mask4
OOB impact with 80MHz channel January 2011 Restricted band
OOB impact with non-contiguous 80MHz channel January 2011 Restricted band
Straw Poll #1 • Do you support adding the amplitude tracking function as an optional specification in spec frame work? Tian-Wei Huang, NTU and Peter Gammel, SiGe