Power Variations with WWiSE Cyclic Preamble Structures January 2005 doc.: IEEE 802.11-05/1581r0 January 2005 Power Variations with WWiSE Cyclic Preamble Structures Date: 2005-01-05 Authors: Notice: This document has been prepared to assist IEEE 802.11. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures <http:// ieee802.org/guides/bylaws/sb-bylaws.pdf>, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair <stuart.kerry@philips.com> as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at <patcom@ieee.org>. Dave Hedberg, Conexant Systems Dave Hedberg, Conexant Systems

January 2005 doc.: IEEE 802.11-05/1581r0 Abstract January 2005 This presentation shows simulation plots of the power variation statistics (as seen at the receiver antennas) between short training preamble segments, which are used by a receiver to set AGC levels, and long training preamble and payload data segments for the WWiSE cyclic shifted preamble structures. Cases examined include both Greenfield and Mixed-mode preamble modes for 20 MHz and 40 MHz multi-antenna transmission modes. In each case, statistics are shown with TGn B, D, and E NLOS channel models. In each case, the power variation for a single antenna (SISO) signal is compared with that of the multiple antenna WWiSE transmission that includes associated cyclic shifts in the preambles. The analysis does not include specific AGC algorithm performance, but only basic signal power variation behavior arising from the different channel statistics.   The results show that the relatively long cyclic shifts employed in the WWiSE Greenfield multi-antenna preambles have well-behaved power variations (e.g. on the order of 0.5 dB rms and close to SISO for the 2-antenna modes). Variations are larger in 3 and 4 antenna modes, but not substantial compared with typical AGC error budget factors. For the legacy preamble portion of mixed-mode signals, the variations of legacy LTS and SF segments can be greater because of the shorter cyclic shifts employed. Laboratory testing has shown that legacy devices can reliably detect these mixed mode legacy signal fields. Dave Hedberg, Conexant Systems Dave Hedberg, Conexant Systems

Outline Introduction 2-Tx Ant 20 MHz Greenfield Modes January 2005 Outline Introduction 2-Tx Ant 20 MHz Greenfield Modes 3-Tx and 4-Tx Ant 20 MHz Greenfield Modes 2-Tx Ant 40 MHz Greenfield Modes Mixed-mode Preamble Modes Conclusions Dave Hedberg, Conexant Systems

January 2005 Introduction We examine power variations of the STS power (used for AGC) relative to LTS power and to average power in 100 random payload data symbols SISO vs. MIMO (multi-antenna transmission) are compared for each mode Power variation CDFs plotted for 2000 channel instances TGn channel models B, D, and E, NLOS Dave Hedberg, Conexant Systems

Back-up Slide ADC Dynamic Range January 2005 Back-up Slide ADC Dynamic Range 9.0 ENOB  55.9 dB + 3 dB (2x OSR) = 58.9 dB total +58.9 dB Max peak with headroom for adjacent channel interference +58.0 dB Max peak level (including PAPR) for max MIMO signal with max peaks +48.0 dB Max signal power including AGC & channel variations 40 dB available signal dynamic range +8.0 dB Nominal Rx thermal noise floor (small signal) 0.0 dBr ADC quantization noise floor (relative to filtered signal) 10 dB additional PAPR headroom 35 dB Max MIMO average SNR +/-2 dB noise AGC uncertainty Dave Hedberg, Conexant Systems

STS to LTS Power Variation - 2-Tx GF20 January 2005 STS to LTS Power Variation - 2-Tx GF20 Ch B, NLOS Ch E, NLOS Ch D, NLOS Dave Hedberg, Conexant Systems

STS to Data Power Variation - 2-Tx GF20 January 2005 STS to Data Power Variation - 2-Tx GF20 Ch B, NLOS Ch E, NLOS Data power in 100 random SISO or 2-stream MIMO symbols Ch D, NLOS Dave Hedberg, Conexant Systems

January 2005 3-Tx and 4-Tx GF20 Modes Dave Hedberg, Conexant Systems

STS to LTS, Data Power Variations - 3-Tx GF20 January 2005 STS to LTS, Data Power Variations - 3-Tx GF20 Ch B, NLOS LTS Data Ch D, NLOS Dave Hedberg, Conexant Systems

STS to LTS, Data Power Variations - 4-Tx GF20 January 2005 STS to LTS, Data Power Variations - 4-Tx GF20 Ch B, NLOS LTS Data Ch D, NLOS Dave Hedberg, Conexant Systems

STS to LTS Power Variation - 2-Tx GF40 January 2005 STS to LTS Power Variation - 2-Tx GF40 Ch B, NLOS Ch E, NLOS Ch D, NLOS Dave Hedberg, Conexant Systems

STS to Data Power Variation - 2-Tx GF40 January 2005 STS to Data Power Variation - 2-Tx GF40 Ch B, NLOS Ch E, NLOS Ch D, NLOS Dave Hedberg, Conexant Systems

Mixed Mode 20 MHz Structure January 2005 Mixed Mode 20 MHz Structure Legacy portion of the preamble (20 us) is utilized for legacy signal field decoding only STS portion of preamble sets the AGC, and is the same in both mixed-mode and Greenfield mode formats Dave Hedberg, Conexant Systems

STS to L-LTS/SF Power Variation - 2-Tx MM20 January 2005 STS to L-LTS/SF Power Variation - 2-Tx MM20 Ch B, NLOS Ch E, NLOS Ch D, NLOS Dave Hedberg, Conexant Systems

January 2005 Summary The relatively long cyclic shifts employed in the WWiSE Greenfield preambles result in well behaved STS power statistics Variations for 2-Tx antenna cases (with 400 ns shift in the STS) track closely the variations seen in legacy SISO modes The power variation statistics for mixed mode receptions of 11n signals are the same as for Greenfield modes -- since the STS portion of the two preamble types is the same The legacy portion of mixed mode preambles employ shorter cyclic shifts for the legacy LTS/SF portion – and consequently exhibit larger variations This part of the preamble is used only for legacy signal field detection Extensive testing of legacy device detection capability with this format is documented in IEEE 802.11-05/1590r0 Dave Hedberg, Conexant Systems

January 2005 References IEEE 802.11/04-0886-06-000n, “WWiSE Proposal: High throughput extension to the 802.11 Standard,” C. Hansen, B. Edwards et al. IEEE 802.11/04-00935-04-000n, “WWiSE IEEE 802.11n Proposal,” S. Coffey et al., Nov. 16, 2004 IEEE 802.11/05-1590-00-000n, “Short Training Sequence Compatibility with Legacy Devices”, Tushar Moorti, et. al. Dave Hedberg, Conexant Systems