Legacy CSD Table for 11AC
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Legacy CSD Table for 11AC. Authors:. Date: 2010-11-8. Slide 1. Summary. Propose a methodology to design legacy CSD for 11ac Minimize the AGC error of the legacy portion of the frame Minimize the power fluctuation of the post AGC signal
Legacy CSD Table for 11AC
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Legacy CSD Table for 11AC Authors: Date: 2010-11-8 Slide 1 Jun Zheng, Broadcom
Summary • Propose a methodology to design legacy CSD for 11ac • Minimize the AGC error of the legacy portion of the frame • Minimize the power fluctuation of the post AGC signal • Propose to reuse the legacy CSD of 802.11n for NTX <= 4 • Optimization of legacy CSD for NTX > 5 • Propose the final legacy CSD tables for 11ac Jun Zheng, Broadcom
Legacy CSD for NTX <= 4 • Propose to reuse 802.11n legacy CSD for NTX <=4 Jun Zheng, Broadcom
Optimization of Legacy CSD • Assume CSDs are multiples of 25ns • Assume CSDs are within the range of [-200ns 0ns] • Minimize AGC error span of the legacy preamble, i.e. from 2.5% to 97.5% of the AGC error CDF of 11n channel model B/C/D/E • In order to capture the random initial phase offset of the TX chain, 2 cases are considered • 0 deg phase shift between even and odd TX antennas • 180 deg phase shift between even and odd TX antennas Jun Zheng, Broadcom
Optimized Legacy CSD for NTX > 4 • Observations: • AGC error of the legacy preamble is usually small • Optimal CSD combinations are not unique • There are more than one CSD combinations provide close to optimal performance in terms of minimizing the legacy AGC error • Power difference between L-STF and VHT-STF could be large Jun Zheng, Broadcom
Further Optimization of Legacy CSD • Assume CSDs are multiples of 25ns • Assume CSDs are within the range of [-200ns 0ns] • Only consider CSD combinations whose AGC error span of the legacy preamble is no greater than 0.1dB of the optimal CSD combination (provide in slide 5) • Minimize the 95 percentile of the absolute power difference between L-STF and VHT-STF for 11n channel model B/C/D/E • In order to capture the random initial phase offset of the TX chain, 2 cases are considered • 0 deg phase shift between even and odd TX antennas • 180 deg phase shift between even and odd TX antennas Jun Zheng, Broadcom
Further Optimized Legacy CSD for NTX > 4 Jun Zheng, Broadcom
Pre-Motion #1 802.11n Legacy CSD table • Do you support to use the following CSD table for legacy preamble and add the language provided in Appendix to Clause 3.2.3.1.1 of the IEEE Specification Framework for TGac ? Jun Zheng, Broadcom
Appendix • Cyclic shift definition: The cyclic shift values defined in this subclause apply to the L-STF, L-LTF, L-SIG, and VHT-SIG-A of the VHT format legacy preamble. The cyclic shift value for the portion of the packet before VHT-STF for transmitter out of total is shown in the following Table: Jun Zheng, Broadcom