TGnSync 802.11 TGn Proposal - IEEE Standards Association

TGnSync 802.11 TGn Proposal - IEEE Standards Association

March 20 05 doc.: IEEE 802.11-04/888r9 TGn Sync Complete Proposal Date: 2005-03-04 Author Name Company Address Phone Email Syed Aon Mujtaba Agere Systems 555 Union Blvd., Allentown, PA 18109, USA +1 610 712 6616 [email protected] 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 IEEEs name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEEs 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 , 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 [email protected]> 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 . Submission Slide 1 Syed A on Muj

March 20 05 doc.: IEEE 802.11-04/888r9 Additional Authors: Name Company email Adrian P. Stephens Intel Corporation [email protected] Alek Purkovic Nortel Networks [email protected] Andrew Myles Cisco Systems [email protected] Andy Molisch Mitsubishi Electric Corporation [email protected] Brian Hart Cisco Systems [email protected] Brian Johnson Nortel Networks [email protected] Chiu Ngo Samsung Electronics Co Ltd

[email protected] Daisuke Takeda Toshiba Corporation [email protected] Daqing Gu Mitsubishi Electric Corporation [email protected] Darren McNamara Toshiba Corporation [email protected] Dongjun (DJ) Lee Samsung Electronic Co Ltd [email protected] David Bagby Calypso Consulting [email protected] Eldad Perahia Cisco Systems [email protected] Hiroshi Oguma Tohoku University [email protected] Hiroyuki Nakase Tohoku University [email protected]

Huanchun Ye Atheros Communications [email protected] Hui-Ling Lou Marvell Semiconductor [email protected] Isaac Lim Wei Lih Panasonic [email protected] James Chen Marvell Semiconductor [email protected] J. Mike Wilson Intel Corporation [email protected] Submission Slide 2 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Jari Jokela Nokia [email protected] Jeff Gilbert Atheros Communications

[email protected] Jin Zhang Mitsubishi Electric Corporation [email protected] Job Oostveen Royal Philips Electronics [email protected] Joe Pitarresi Intel Corporation [email protected] Jorg Habetha Royal Philips Electronics [email protected] John Ketchum Qualcomm Incorporated [email protected] John Sadowsky Intel Corporation [email protected] Jon Rosdahl Samsung Electronics Co Ltd [email protected] Kiyotaka Kobayashi Panasonic [email protected]

Li Yuan Institute for Infocomm Research [email protected] Luke Qian Cisco Systems [email protected] Mary Cramer Agere Systems [email protected] Masahiro Takagi Toshiba Corporation [email protected] Monisha Gosh Royal Philips Electronics [email protected] Nico van Waes Nokia [email protected] Osama Aboul-Magd Nortel Networks [email protected] Paul Feinberg Sony Electronics [email protected] Pen Li Royal Philips Electronics

[email protected] Peter Loc Marvell Semiconductor [email protected] Submission Slide 3 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Ronald Rietman Royal Phiips Electronics [email protected] Sanjiv nanda Qualcomm Incorporated [email protected] Seigo Nakao Sanyo Electric Co Ltd [email protected] Sheung Li Atheros Communications [email protected] Stephen Shellhammer Intel Corporation [email protected]

Subra Dravida Qualcomm Incorporated [email protected] Sumei Sun Institute for Infocomm Research [email protected] Taekon Kim Samsung Electronics Co Ltd [email protected] Takashi Fukugawa Panasonic [email protected] Takushi Kunihiro Sony Corporation [email protected] Teik-Kheong (TK) Tan Royal Philips Electronics [email protected] Tomoko Adachi Toshiba Corporation [email protected] Tomoya Yamaura Sony Corporation [email protected] Tsuguhide Aoki Toshiba Corporation

[email protected] Victor Stolpman Nokia [email protected] Won-Joon Choi Atheros Communications [email protected] Xiaowen Wang Agere Systems [email protected] Yasuhiko Tanabe Toshiba Corporation [email protected] Yasuhiro Tanaka Sanyo Electric Co Ltd [email protected] Submission Slide 4 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Yoshiharu Doi Sanyo Electric Co Ltd [email protected]

Youngsoo Kim Samsung Electronic Co Ltd [email protected] Yuichi Morioka Sony Corporation [email protected] Yukimasa Nagai Mitsubishi Electric Corporation [email protected] Submission Slide 5 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Abstract This document describes the TGn Sync complete proposal submission to IEEE 802.11 TGn Submission Slide 6 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 TGn Sync Mission Statement Develop

a scalable architecture to support present and emerging applications Foster a broad industry representation across market segments Submission Slide 7 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Broad Industry Representation OEM / System Vendors Asia Pacific / Europe / North America Consumer Electronics

Public Access Agere Atheros Intel Marvell Philips Qualcomm Handset Semiconductor Academia Submission Enterprise Semi Vendors PC Cisco InterDigital (NEW) Mitsubishi Electric Nokia Nortel Panasonic Samsung Sanyo Sharp Sony Toshiba Wavebreaker/ATcrc Wavion Academia Infocomm Tohoku University Slide 8 Syed A on Muj March 20

05 doc.: IEEE 802.11-04/888r9 Scalable Architecture across several dimensions Market Segment s Residential Enterprise Public Access Portable Devices 144Mbps Asia Pacific Regulatory Domains Submission Europe North America Slide 9 300Mbps 600Mbps Performanc e Over Time Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 PHY Summary of TGn Sync Proposal Mandatory Features: 1 or 2 Spatial Streams 20MHz Channelization

1/2, 2/3, 3/4, and 5/6 channel coding rates RX assisted Rate Control 400ns & 800ns Guard Interval Full & seamless interoperability with a/b/g 144 Mbps in 20MHz Optional Features: 40MHz channelization Transmit Beamforming Low Density Parity Check (LDPC) Coding support for 3 or 4 spatial streams *Not required in regulatory domains where prohibited. Submission Slide 10 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 MAC Summary of TGn Sync Proposal Mandatory Features: MAC level aggregation RX assisted link adaptation QoS support (802.11e)

Block ACK compression Legacy compatible protection 20/40 MHz channel management Optional Features: Bi-directional data flow MIMO RX Power management Submission Slide 11 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 PHY Submission Slide 12 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 PHY Architectural Features

Mandatory features: Spatial division multiplexing (SDM) of 2 Spatial Streams Interoperable 20MHz and 40MHz channelizations Channel Coding Rates: 1/2, 2/3, 3/4, and 5/6 Support for RX assisted Rate Control Guard Interval: 400ns and 800ns Max Mandatory rate in 20MHz = 144 Mbps (with 2x2 architecture using 2 spatial streams) Optional robustness & throughput enhancement: 40 MHz channelizations Transmit beamforming Advanced coding (LDPC) SDM with 3 or 4 spatial streams with the option to scale to 600Mbps Submission Slide 13 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 PHY Modifications after Monterey (Jan 05) 40MHz operation made optional Expanded data tones from 48 to 52 in 20MHz

previously it was 7/8 Reduced the HT-LENGTH field indicator from 19 bits to 12 bits Adopted a format for sounding packets total is 56 tones now Number of Pilots stay at 4 Dropped highest coding rate to 5/6 previously it was mandatory sounding packets are those in which NSS NTX sounding packets enable complete antenna-to-antenna channel estimation Removed option for unequal power loading in TX Beamforming Introduced a new extended MCS set for TX Beamforming constant code rate with variable modulation levels Submission Slide 14 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Scalable PHY Architecture

Mandatory Open Loop SDM Conv. Coding RX assisted Rate Control 2 Spatial Streams 20 MHz Robustness Enhancement Robustness Enhancement Throughput Enhancement Throughput Enhancement 144 Mbps Submission Optional Closed Loop TX BF LDPC 4 Spatial Streams 40 MHz 600 Mbps Slide 15 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Mapping Spatial Streams to Multiple Antennas Number of spatial streams = Number of TX antennas

Direct map 1 spatial stream to 1 antenna Spatial division multiplexing Equal rates on all spatial streams Number of spatial streams Number of TX antennas Each spatial stream mapped to all transmit antennas Optional transmit beamforming Optimal technique for realizing array and diversity gains Requires channel state info at the TX Supports unequal rates on different spatial streams Optional orthogonal spatial spreading Exploits all transmit antennas No channel state info at TX required Submission Due to per spatial stream training, no change is needed at the RX to support optional techniques Slide 16 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Parameters in Link Adaptation Basic MIMO Beamformed MIMO Stream Control Yes Yes Rate (MCS) Control

Yes Yes (per stream) GI selection Yes Yes TX Per-Tone Steering Matrix No Yes Per Stream Power Loading No No Submission Slide 17 NEW Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Mandatory PHY Features Submission Slide 18 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9

TX Arch: Spatial Division Multiplexing e.g. 2 Spatial streams with 2 TX antennas Preamble Pilots Spatial parser Puncturer Channel Encoder Scrambled MPDU Frequency Interleaver insert GI window symbols insert GI window symbols Constellation Mapper Preamble Pilots Frequency Interleaver Submission iFFT Modulator iFFT Modulator Constellation Mapper Slide 19

Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Tone Design for 20MHz 52 data tones (2 extra on each side) 4 pilot tones -28 Submission -26 -21 -7 -1 +1 Slide 20 +7 +21 +26 +28 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Mandatory MCS Set Modulation Data Rates 20 MHz (Mbps) Code Rate 1 Spatial Stream

2 Spatial Streams BPSK 1/2 7.22 14.44 QPSK 1/2 14.44 28.88 QPSK 3/4 21.67 43.34 16 QAM 1/2 28.89 57.78 16 QAM 3/4 43.33 86.66 64 QAM 2/3 57.78 115.56

64 QAM 3/4 65 130 64 QAM 5/6 72.22 144.44 GI applies to all data rates in 20MHz Submission Slide 21 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 HT-PPDU Format in 20MHz HT LTF-2 20MHz HT LTF-1 L-STF L-LTF L-SIG HT-SIG HT-DATA 20MHz ANT_2

ANT_1 HT STF L-STF L-LTF L-SIG HT-SIG HT-DATA Legacy Compatible Preamble Legend LHTSTF LTF SIG Submission HT-specific Preamble Legacy Compatible Can be decoded by any legacy 802.11a or g compliant device for interoperability Legacy High Throughput Short Training Field Long Training Field Signal Field Slide 22 Syed A on Muj March 20 05 L-STF doc.: IEEE 802.11-04/888r9 Spoofing L-LTF LSIG

HT-SIG HT STF HT LTF HT LTF Data Legacy RATE and LENGTH fields => Packet Length in OFDM Symbols Spoofing is the use of the legacy RATE and LENGTH fields to keep the legacy STA off the air for a desired period of time The duration indicated in the L-SIG can exceed the actual duration in the HT-SIG MAC uses this as a protection mechanism For a HT-PPDU, L-SIG RATE is hard-coded at 6 Mbps Submission max MSDU length = 2304 Bytes spoofing duration up to ~3 msec Slide 23 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 HT PPDU Detection L-STF L-LTF L-SIG HT-SIG

or L-STF L-LTF L-SIG Legacy DATA Legacy Compatible Preamble Auto-detection Submission scheme on HT-SIG Q-BPSK modulation (BPSK w/ 90-deg rotation) Invert the polarity of the pilot tones Combined methods provide speed and reliability Slide 24 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 MIMO AGC single spatial stream L-STF power measurement L-LTF L-SIG multiple spatial streams HT-SIG HT-DATA AGC locked

Accurate measurement of MIMO channel power requires uncorrelated STFs NTX * Power _ RX j Power _ TX h ji h ji i 1 Tone interleaving the L-STF leads to perfect decorrelation E STFi ( f ) STF j* ( f ) 0 if L-STF is tone-interleaved, it will hurt legacy interoperability with cross-correlation RX Cyclic delay across the L-STF is nearly decorrelated however, large cyclic delay hurts interoperability with cross-correlation RX and, small cyclic delay suffers from inaccurate power estimation, as shown next Submission Slide 25 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Power Fluctuation of L-STF w.r.t Data Data power 1 0.9 STF = Tone Interleaved

STF = Cyclic Delay 0.8 2x2, TGn Channel D SNR = 30dB 0.7 CDF(x) Power fluctuation with tone interleaving is within 1dB of the data power 0.6 0.5 Introduce a dedicated STF for MIMO that is tone interleaved 0.4 0.3 0.2 0.1 0 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 Reduces 1 bit in the

ADC cost & power savings x = Power fluctuation of AGC setting w.r.t. data power (dB) Submission Slide 26 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Power Fluctuation of HT-LTF w.r.t. Data Data power 1 0.9 HT-LTF = Tone Interleaved 0.8 HT-LTF = Walsh + Cyclic Delay 0.7 CDF(x) Large deviation of HT-LTF power wrt data power will result in higher channel estimation error 2x2, TGn Channel D SNR = 30dB 0.6 0.5 0.4 0.3 0.2 HT-LTF should be tone interleaved

0.1 0 -10 Submission -8 -6 -4 -2 0 2 x = Power fluctuation of HT-LTF w.r.t. data (dB) Slide 27 4 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Tone Interleaved HT Training Fields HT SIG 2 HT STS LTS1 LTS2 LTS1 LTS2 DATA HT SIG 2 HT STS LTS1 LTS2 LTS1 LTS2

DATA HT SIG 2 HT STS LTS1 LTS2 LTS1 LTS2 DATA HT STF HT LTF HT-STF HT LTF 2nd AGC measurement is used to fine-tune MIMO reception HT-LTF Submission Used for MIMO channel estimation Additional frequency or time alignment Slide 28 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9

Spatial Stream Tone Interleaving 1 Spatial Stream 2 Spatial Streams 3 Spatial Streams 4 Spatial Streams Color indicates spatial stream Each HT-LTF has equal representation from all spatial streams Eliminates avg. power fluctuation across LTFs HT-LTS symbols are designed to minimize PAPR Distinct symbol designs for different number of spatial streams Submission Slide 29 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Summary of HT-LTF Robust design Tone interleaving reduces power fluctuation 2 symbols per field 3dB of channel estimation gain with baseline per-tone estimation Enables additional frequency offset estimation Per spatial stream training HT-LTF and HT-Data undergo same spatial transformation Number of HT-LTFs = Number of spatial streams

Submission Slide 30 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Preamble Format Comparison .11a preamble Tx1 L-STF L-LTF L-SIG TGn Sync preamble (2TX) Tx1 L-STF L-LTF L-SIG Tx2 L-STF(50ns) L-LTF(50ns) L-SIG(50ns) WWiSE preamble (2TX Mixed-mode) Tx1 L-STF Tx2 L-STF(400ns) L-LTF

L-SIG L-LTF(3100ns) L-SIG(3100ns) Values shown in brackets indicate the amount of CDD delay Submission Slide 31 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Legacy Interoperability of Preamble Cross-correlation of L-STS (TGn Sync) Cross Correlation with STS 0.009 0.008 Period = 800ns 0.006 0.005 0.004 0.003 0.002 Cross-correlation of L-STS (WWiSE) Cross Correlation with STS 0.001 0.008 0 0 0.5

1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 0.007 microseconds Absolute Value of Cross Correlation Absolute Value of Cross Correlation 0.007 Period = 400ns Potential issues with crosscorrelation receivers with WWiSE preamble Submission 0.006 0.005 0.004 0.003

0.002 0.001 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 microseconds Slide 32 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Test Setup Test packets generated in C simulator

TX signals are convolved with a simulated TGn channel Signal generator is used for up-conversion C simulator Tx1 Packet TGn generator Tx2 Channel model Agilent E4438C Rx1 Single input single output Normalized signal generator Slide 33 Syed A on Muj ref: IEEE doc. 802.11-05/0006r0 Submission March 20 05 doc.: IEEE 802.11-04/888r9 Measurement Setup TGn simulator Aeropeek NX Compare the RATE and LENGTH RATE LENGTH RATE LENGTH Wireless 5.19GHz 10cm apart Omni transmit antenna Agilent E4438C

Enhanced Signal Generator (ESG) Submission Slide 34 WLAN card under test Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Laboratory Measurement Results (Legacy AutoCorrelation RX) "Aut o Correl at i on Vendor" ( Channel D) Measured SI G error 1. 00E+00 1TX - . 11a 2TX - TGnSync ( 50ns) 2TX - WWiSE ( 400ns) 1. 00E- 01 1. 00E- 02 1. 00E- 03 - 30 Submission - 25 - 20 - 15 - 10 Normal i zed Tx power f romESG [ dB] Slide 35 -5 0 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9

Laboratory Measurement Results (legacy CrossCorrelation RX) "Cross Correl ati on Vendor" ( Channel D) Measured SI G error 1. 00E+00 Performance limitation with a WWiSE preamble 1. 00E- 01 1. 00E- 02 1TX - . 11a 2TX - TGnSync (50ns) 2TX - WWiSE ( 400ns) 1. 00E- 03 - 30 Submission - 25 Error Floor! - 20 - 15 - 10 Normal i zed Tx power f romESG [dB] Slide 36 -5 0 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Implication of using WWiSE preambles Legacy devices with a cross-correlation RX will not correctly decode a WWiSE preamble Hence, such legacy devices will not defer to a WWiSE HT transmission, potentially creating collisions in the BSS

BSS throughput would drop, and latency would increase WWiSE preamble is not legacy compatible Lab test reinforces TGn Syncs decision to use a 100% backwards compatible legacy preamble Submission Slide 37 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 TGn Sync enhanced interleaver SISO (11a/g) MIMO 2x 11a Bit interleaver, Permutation Operation 1 11a Bit interleaver, Permutation Operation 2 11a Bit interleaver, Permutation Operation 1 11a Bit interleaver, Permutation Operation 2 1st Spatial Stream 2nd, 3rd, or 4th Spatial Stream parser 11a Bit interleaver, Permutation Operation 1

11a Bit interleaver, Permutation Operation 2 Channelization 20MHz 40MHz Total # of Streams 1 2 3 4 1 2 3 4 1st stream 0 0 0 0 0 0 0 0 22 22

22 58 58 58 11 11 29 29 Frequency Rotation Submission Frequency Rotation nd 2 stream rd 3 stream th 33 4 stream Slide 38 87 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9

2 vs 4 pilots in MIMO The TGn Sync Proposal uses the full 4 pilots (like .11a/b/g) 2 pilots in WWiSE provide marginal data rate increase: < 4% Full CC67 sims to compare multi- and single-stream cases: Since data also will have diversity gain, and thus require less operating SNR, would the pilots now limit performance? Single stream modes important: CDD (TGn Sync) , STBC (WWiSE) Analysis must consider differences in 11n vs. 11a: Different preambles, antenna configurations Decoded data SNR improved due to MIMO (e.g, MRC, STBC) Thus pilot accuracy requirements also increase Comparing 11n pilot SNR to 11a is thus not sufficient Robustness to narrowband interference and impairments These both reduce effective number of pilots thus need margin Full details in doc. 11-05/1636r0 Submission Slide 39 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Dual Stream Performance 2 vs 4 Pilots with 2 streams, 2x2, E NLOS 1.E+00 2 streams, BPSK, 1/2, 2 pilots

Packet Error Rate 2 streams, BPSK, 1/2, 4 pilots 1.E-01 1.E-02 1 dB 1.E-03 5 10 15 20 Average SNR [dB] Submission Slide 40 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Single Stream Performance 2 vs 4 Pilots with single stream, 2x2, E NLOS 1.E+00 1 stream, BPSK, 1/2, 2 pilots Packet Error Rate 1 stream, BPSK, 1/2, 4 pilots 1.E-01 1.E-02 3.5 dB 1.E-03 5 10

15 20 Average SNR [dB] Submission Slide 41 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Summary of 2 vs 4 pilots Quantitative analyses show that using only 2 pilots causes significant performance degradation in many situations 4 vs 2 pilots compared for 2x2 basic MIMO channel E Dual stream: ~1dB loss Single stream: 1.5~3.5dB loss. Robustness Performance loss w/ narrow-band interference or impairments: 4 ~ 6dB loss with 2 pilots -> NOT ROBUST !! Performance penalty of using only 2 pilots is not justified by the less than 4% data rate increase Submission Slide 42 Syed A on Muj March 20 05

doc.: IEEE 802.11-04/888r9 Importance of Rate Feedback and Stream Control Throughput is maximized if there is rapid convergence to a good choice of stream count and MCS Receiver determines its preferred stream count and MCS Based on observation of received HT-LTF in sounding packet Sends this choice back to transmitter using MCS Feedback (MFB) Transmitter makes a rate choice based on the MCS selection at RX Initial MCS/stream selection Ongoing tracking and optimization Under some circumstances, e.g. pairwise spoofing, TX must adhere to MFB Important for Basic MIMO, Spatial Spreading and Beamforming Submission Slide 43 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Rate feedback in Basic MIMO

MRQ (MCS Request) is sent in sounding packet: RX gets estimate of full H matrix Channel quality estimates based on H matrix guide rate and stream selection MRQ payload in PHY sounding packet TX Ant1 RX h11 h12 h21 Ant2 h22 Full H matrix h11 H h12 Number of streams and coding rate carried in Slide 44 Submission MFB h21 h1 h22 h 2 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Stream/Rate Control Approaches SNR calculation performed at equalizer

output: Can provide stream count and MCS selection Includes impairments due to channel estimation errors SNR calculation performed by re-encoding decoded data and comparing it against decoder input: Submission allows MCS selection, but not stream count Slide 45 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Close Loop vs Open Loop Throughput Comparison Open loop vs closed loop comparison for 2x2 TxBf = Transmit Beamforming; SS=Spatial spreading Open vs. Closed loop 200 MAC throughput [Mbps] 180 160 140 TxBf 2% 120 SS closed loop 2% SS open loop 2%

100 TxBf 10% 80 SS closed loop 10% 60 SS open loop 10% 40 20 0 10 15 20 25 30 35 40 45 50 SNR [dB] Submission Slide 46 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 MSDU Delay CDF Target PHY PER = 10% TxBf closed loop 10% PER SS closed loop 10% PER

SS open loop 10% PER Submission Slide 47 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Optional PHY Features Submission Slide 48 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Tone Format in 40MHz Tone Fill in the Guard Band 40 MHz: 128 point FFT 108 data tones 6 pilot tones -25 -53 -64 -58 -32 -11 +11 -6

Legacy 20 MHz in Lower Sub-Channel Submission -2 +2 +6 +25 +53 +32 +58 +63 Legacy 20 MHz in Upper Sub-Channel Slide 49 Syed A on Muj 40MHz ANT_1 March 20 05 doc.: IEEE 802.11-04/888r9 HT-PPDU Format in 40MHz L-STF L-LTF L-SIG HT-SIG HT-DATA Duplicate Duplicate Dup. Duplicate L-STF L-LTF

L-SIG HT-SIG 40MHz ANT_2 HT STF L-STF L-LTF L-SIG HT LTF-1 HT LTF-2 HT-SIG HT-DATA Duplicate Duplicate Dup. Duplicate L-STF L-LTF L-SIG HT-SIG Legacy Compatible Preamble Submission HT-specific Preamble Slide 50 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 20/40 MHz Operation Where Used Where Bought 20/40 MHz Region (e.g. in US/Europe) 20/40 MHz Capable 40 MHz Operation Device

(20 MHz Operation) (e.g. in US/Europe) 20 MHz only Capable Device (e.g. in Japan) Submission Seamless 20 MHz operation in a 40 MHz BSS Slide 51 20 MHz Region (e.g. in Japan) 20 MHz Operation; 40 MHz disabled 20 MHz Operation Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 20/40 MHz Interoperability 40 MHz PPDU into a 40 MHz receiver 20 MHz PPDU into a 40 MHz receiver The active 20 MHz sub-channel is detected as the 20 MHz sub-channel with higher energy, cross-correlation or autocorrelation, etc. 40 MHz PPDU into a 20 MHz receiver

Get 3dB processing gain duplicate format allows combining the legacy compatible preamble and the HT-SIG in an MRC fashion One 20 MHz sub-channel is sufficient to decode the L-SIG and the HT-SIG 20 MHz RX (either HT or legacy) will defer properly to 40 MHz PPDU See MAC slides for additional information on 20/40 inter-op Submission Slide 52 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Benefit of 40MHz channelization 2x2 40 MHz Only 2 RF chains => Cost effective & low power Lower SNR at same throughput => Enhanced robustness 260 240 220 Over the Air Throughput (Mbps) 200 180 2x2-40 MHz 160 4x4-20 MHz Sweet spot for 100 Mbps top-of-MAC 2x3-20 MHz w/ short GI 140 2x2-20 MHz w/ short GI 120 100 80

60 Basic MIMO MCS set No impairments 1000 byte packets TGn channel model B 40 20 0 0 5 10 15 20 25 30 35 SNR (dB) Submission Slide 53 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Seamless Arch Extension for TX BF Spatial Parser Puncturer Channel Encoder Scrambled MPDU

Frequency Interleaver HT LTF Pilots Frequency Interleaver Submission Constellation Mapper Constellation Mapper Slide 54 insert GI iFFT Mod. insert GI iFFT Mod. insert GI window Pilots iFFT Mod. window HT LTF window Per Spatial Stream Processing: HT-LTF & HT-Data undergo same spatial transformation

Spatial Steering Matrix e.g. 2 Spatial Streams across 3 Transmit Antennas Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Why introduce TX Beamforming? 160 2x2 - SDM 140 2x3 - SDM 2x2 - Advanced BF 3x2 - Advanced BF Over-the-Air Throughput (Mbps) 120 4x2 - Advanced BF 100 1000 byte packets No impairment 20MHz, channel D 80 60 4 TX-antenna AP 2 RX-antenna client ~10 dB gain of 4x2-ABF over 2x2-SDM => cost effective client 40 20 0 0 5

10 15 20 25 30 35 SNR (dB) Submission Slide 55 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 WWiSE proposal can not support Tx Beamforming Problem Problem WWiSE channel estimation requires smoothing algorithms Channel smoothing is problematic with MIMO Beamforming WWiSE GF structure does not allow omni-directional transmission of SIG-N Result: Hidden node problems

ref: doc. 11-05/1635r1 Submission Slide 56 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Why smoothing is bad for MIMO BF? Smoothing requires high adjacent tone coherence However, we must estimate the combined channel Heffective = Hchannel * Vbeamforming Beamforming matrix has poor adjacent tone coherence Why? Eigen-channel rank reversals For each tone, eigen-channels are ranked by singular values Eigen-channels can reverse ranks on adjacent tones resulting in an adjacent tone swap of corresponding columns of BF matrix Result very low adjacent tone coherence Submission Slide 57 Syed A on Muj Singular Value (dB) March 20 05 doc.: IEEE 802.11-04/888r9 Example: 4x4, Channel D

15 10 5 0 -5 -10 -15 -20 -10 -8 -6 -4 -2 0 2 4 6 8 10 2 4 6 8 10 Frequency (MHz) 1.00 abs( rho ) 0.95 0.90 0.85 0.80 0.75

-10 -8 -6 -4 -2 0 Frequency (MHz) Submission Slide 58 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Optional LDPC Capacity approaching FEC Strong performance in AWGN and fading channels Iterative decoding superior performance Typically 1.5-3 dB improvement over convolutional codes, depending on channel conditions Code structure enables low complexity architectures Layered belief propagation reduces memory requirements and improves convergence performance Submission

Slide 59 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Benefit of LDPC Coding CC67 simulation. LDPC (dashed), CC (solid) Submission Slide 60 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 PHY Summary Mandatory Rate of 144Mbps in 20MHz: Low Cost & Robust Throughput Enhancement: 2 Spatial Streams 52 data tones in 20MHz 5/6th rate coding 400ns Guard Interval RX assisted Rate Control Scalable to 300 Mbps in 40MHz with 2 Spatial Streams Optional Robustness/Throughput Enhancements:

Submission LDPC Coding Transmit Beamforming Scalable to 600Mbps with 4 spatial streams in 40MHz Slide 61 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 MAC Submission Slide 62 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Scalable MAC Architecture LEGACY INTEROP. Long NAV Pairwise Spoofing Single-Ended Spoofing BASELINE MAC Robust Aggregation QoS Support (802.11e) Rx assisted link adapt. ADDITIONAL EFFICIENCY Multi-Receiver Aggregation Bi-Directional Data Flow BA Enhancements Robust &

Scalable MAC Architecture CHANNEL MANAGEMENT 20/40 MHz Modes Submission Slide 63 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Modifications to MAC Arch January 2005 to March 2005 Removed TRMS Power-Saving MPDU Header Compression Added Precise TSF Synchronization support Max PSDU Length Capability Submission Slide 64 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Baseline MAC Features Submission

Slide 65 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 A-MPDU Aggregation Structure Robust Structure Aggregation is a purely-MAC function PHY has no knowledge of MPDU boundaries Simplest MAC-PHY interface Control and data MPDUs can be aggregated PSDU Submission Slide 66 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 A-MSDU Aggregation Structure Carrier MPDU Frame Control Dur / ID Address Address Address Seq Address QoS

1 2 3 Control 4 Control Efficient Structure MSDUs of the same TID can be aggregated MSDUs with differing SA/DA can be aggregated Submission AMSDU Subframe 1 Subframe 2 ... Subframe Header MSDU Pad 14 B 0-2304 B 0-3 B DA SA Len 6B 6B 2B Slide 67

FCS Subframe n Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 A-MPDU Aggregate Exchange Sequences A-MPDU Aggregate exchange sequences include single frames or groups of frames that are exchanged at the same time Allows effective use of Aggregate Feature Allows control and data to be sent in the same PPDU An initiator sends a PPDU and a responder may transmit a response PPDU Either PPDU can be an aggregate (Initiator / responder are new terms relating to roles in aggregate exchange protocol) Submission Slide 68 Syed A on Muj March 20 05 RTS/CTS Protocol Submission

doc.: IEEE 802.11-04/888r9 Basic Aggregate Exchange Implicit Block Ack Protocol Slide 69 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 RX Assisted Link Adaptation Protocol Support for PHY closed-loop modes with on-the-air signalling Request for training and feedback are carried in control frames Rate feedback supported Transmit beamforming training supported sounding packet calibration exchange Timing of response is not constrained permitting a wide range of implementation options Submission Slide 70 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 RX Assisted Link Adaptation Protocol

Submission Slide 71 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Features Providing Additional Efficiency Submission Slide 72 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Reverse Direction Data Flow Gives an opportunity for a responder to transmit data to an initiator during the initiators TXOP Aggregates data with response control MPDUs Reduces Contention Effective in increasing TCP/IP performance Submission Slide 73 Syed A on Muj Submission Agg PPDU Basic rate non-agg

Slide 74 Block Ack Data MPDU Data MPDU BAR MPDU RAC MPDU RAC MPDU (CTS+RDR) Responder Tx Activity PHY Tx MAC Tx RDG Duration Agg PPDU Agg PPDU Basic rate non-agg BA MPDU Data MPDU Data MPDU Data MPDU IAC MPDU Data MPDU Data MPDU Data MPDU Data MPDU IAC MPDU (RDG) IAC MPDU (RTS+ RDL) Initiator Tx Activity PHY Tx MAC Tx March 20

05 Reverse Direction Protocol doc.: IEEE 802.11-04/888r9 Reverse Direction Protocol Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Enhanced BA Mechanism The originator may omit the inclusion of a BAR frame in an aggregated frame (Implicit BAR). Defines a compressed variant of the 802.11e BA MPDU (Compressed BA). Support for non-fragmented BA. This reduces the bitmap size to 1 bit per MSDU. Truncation of the bitmap to reduce the number of MSDUs acknowledged in the bitmap. Aggregation frame MD Initiator D1 D2 D3 D4 SIFS Compressed BA Responder 1 128 Frame Control

Duration/ ID Compressed Submission RA Non-Frag TA BA Control BA Starting Seq. Control Num MSDU Slide 75 TID BlockAckBitmap FCS BA Bitmap size is fixed through BA setup. Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Multiple Receiver Aggregation Aggregates can contain MPDUs addressed for multiple receiver addresses (MRA) MRA may be followed by multiple responses from the multiple receivers MRA is effective in improving throughput in applications where frames are buffered to many receiver addresses

Submission Slide 76 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Multiple Responses Initiators PPDU IAC: Offset Duration IAC: Offset Duration IAC: Offset Duration Offset 1 Duration 1 Response from RA1 Offset 2 Duration 2 Response from RA2 Offset 3 Duration 3 Response from RA 3 MRA contains multiple IAC for One per response At most one per receiver

IAC specifies response offset and duration Submission Slide 77 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Legacy Interoperability and Channel Management Submission Slide 78 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Protection Mechanisms LongNAV Pairwise Spoofing An entire sequence is protected by NAV set using MPDU duration field or during contention-free period CF-end packet at end of EDCA TXOP sequence may be used to return unused time by resetting NAV Protection of pairs of PPDUs sent between an initiator and a single responder

Uses Legacy PLCP header duration spoofing Single-ended Spoofing Protection of aggregate and any responses using legacy PLCP spoofing at the initiator only Can be used to protect multiple responses Submission Slide 79 Syed A on Muj March 20 05 LongNAV protection Provides protection of a sequence of multiple PPDUs Provides a solution for .11b Comes for free with polled TXOP Gives maximum freedom in use of TXOP by initiator NAV Value IAC (RTS) Agg RAC (CTS) CFEnd Agg Agg Agg Resets the NAV

Nominal End of TXOP doc.: IEEE 802.11-04/888r9 NAV Value Nav Timer Non-Zero Submission Slide 80 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Pairwise Spoofing Protection Protects pairs of PPDUs (current and following) Very low overhead, suitable for short exchanges, relies on robust PHY signaling Places Legacy devices into receiving mode for spoofed duration Spoofing is interpreted by HT devices as a NAV setting Submission Slide 81 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Single-Ended Spoofing Protection

Protects MRA and all responses Very low overhead, suitable for short exchanges Places legacy devices into receiving mode for spoofed duration Same level of protection as initiator CTS-to-Self Assuming CTS is sent at the lowest rate Submission Slide 82 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Operating Mode Selection BSS operating mode controls the use of protection mechanisms and 20/40 width switching by HT STA Supports mixed BSS of legacy + HT devices HT AP-managed modes If only the control channel is overlapped, managed mixed mode provides a low overhead alternative to mixed mode If both channels are overlapped, 20 MHz base mode allows an HT AP to dynamically switch channel width for 40 MHzcapable HT STA Submission Slide 83 Syed A on Muj March 20

05 doc.: IEEE 802.11-04/888r9 20 MHz-base Managed Mixed Mode ch_a (control) Carrier Sense (CS) Bcn/ ICB CS CTS self /Bcn CFEnd 40MHz CS RCB CFEnd CFEnd 20MHz t 20MHz t ch_b (extension) NAV ch_a NAV NAV ch_b NAV NAV ch_a+ch_b Submission

NAV NAV Slide 84 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 System Simulation Results Compliant to TGn FRCC requirements 3 independent MAC simulations 802.11-04/893 802.11-04/894 802.11-04/1359 FRCC Results and analysis of MAC features is presented in 802.11-04/892 Detailed description of MAC simulation methodology in 802.11-04/895 Submission Slide 85 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Selected System CC Performance CC# CC3 CC18

CC19 CC58 Name Result HCCA EDCA 2x2x20 2x2x40 2x2x20 2x2x40 SS1 (Mbps) 85 85 77 85 SS1 + 103 163 94 147 SS4 104 218 95 203 SS4 +

105 223 99 213 SS6 65 65 65 65 SS6 + 90 179 82 164 HT Usage Models Supported Non-QoS (Measured aggregate throughput/ offered aggregate throughput) SS1 (Mbps/ratio) 33/1.0 33/1.0 24/0.79 33/1.0 SS4 95/0.21 209/0.46

86/0.19 195/0.43 SS6 21/1.0 21/1.0 21/1.0 21/1.0 HT Usage Models Supported (number of QoS flows that meet their QoS requirements) SS1 17 of 17 17 of 17 17 of 17 17 of 17 SS4 18 of 18 18 of 18 18 of 18 18 of 18 SS6 39 of 39 39 of 39 39 of 39 39 of 39 bps/Hz

5.62 6.04 5.62 6.04 List of goodput results for usage models 1, 4 and 6. HT Spectral Efficiency Submission Slide 86 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Value of MAC Features Featur CondiValue tion e S1 (Mbps) S4 (Mbps) S6 (Mbps) TGn bis TGn bis TGn bis Pairwise

spoofing (vs LongNav) 610% Long NAV 70.25 - 71.57 - 49.92 - Pairwise Spoofing 77.52 - 78.64 - 53.06 - Enhanced BA 212% - 73.30 - 92.40 - 63.80

- + 75.40 - 103.3 - 65.10 - - 82.08 87.26 90.60 126.9 1 62.56 66.96 + 83.85 * 94.67 123.2 8 141.0 2 66.00 96.24 +Periodic RDR

- - 142.1 2 160.1 2 - - Reverse Direction Submission 536% 26 56% Slide 87 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 MAC Summary Baseline Features Additional MAC Efficiency Multi-Receiver Aggregation Bi-Directional Data Flow

Enhanced Block ACK Legacy Compatible Protection Mechanisms MAC Level A-MPDU and A-MSDU Aggregation QoS Support (802.11e) Receiver assisted link adaptation Long NAV Pairwise Spoofing Single Ended Spoofing Scalable Channel Management Submission 20/40 MHz Operating Modes Slide 88 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 List of References IEEE 802.11-04/887, "TGnSync Proposal Summary" IEEE 802.11-04/888, "TGnSync Proposal (This document)

IEEE 802.11-04/889, "TGnSync Proposal Technical Specification" IEEE 802.11-04/890, "TGnSync Proposal FRCC Compliance" IEEE 802.11-04/891, "TGnSync Proposal PHY Results" IEEE 802.11-04/892, "TGnSync Proposal MAC Results" IEEE 802.11-04/893, "TGnSync Proposal MAC1 Simulation Results" IEEE 802.11-04/894, "TGnSync Proposal MAC2 Simulation Results IEEE 802.11-04/1359, "TGnSync Proposal MAC3 Simulation Results IEEE 802.11-04/895, "TGnSync Proposal MAC Simulation Methodology" You may also direct questions to [email protected] For additional details, refer to http://www.tgnsync.org Submission Slide 89 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Modifications since Nov 2004 PHY MAC Made 40MHz optional Increased data tones to 52 in 20MHz Dropped highest coding rate to 5/6 Adopted constant code rate with variable modulation in TxBf Dropped unequal power loading option in TxBf Adopted format for sounding packet Adopted optimized definition of HTLENGTH field Submission Slide 90 Added

Precise TSF Synchronization Max PSDU Length capability Removed TRMS Power Saving mode MPDU Header Compression Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Scalable Architecture across several dimensions Market Segment s Residential Residential Enterprise Enterprise Public Access Access Public Portable Devices Tx Beamforming MRMRA Efficiency for isochronous clients (VoIP) Coverage throughout

MRAD Tx beamforming Reverse direction Lower Power Extended range for devices Hot Spot support for portable saving 802.11n rates Reverse direction assisted RX Range extension andAdaptation robustness for Increased efficiency for gaming Link Higher network handsets efficiency for bulk data transfer 144Mbps Higher throughput in congested MRMRA environments

Asia Pacific Regulatory Domains Submission the home Europe North America Slide 91 300Mbps Power savings and600Mbps robustness for handset mobility Performanc e Over Time Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Key Features Scalable PHY & MAC Architecture 20 and 40 MHz channels fully interoperable Data rate scalable to 600 Mbps Legacy interoperability all modes Robust preamble Transmit beamforming Robust frame aggregation Bi-directional data flow Fast link adaptation Submission Slide 92 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9

Glossary CRC Cyclic Redundancy Check MPDU Agg BA BAR BSS CHDATA CTS FCS Aggregate Block Ack Block Ack Request Basic service set Compressed header data Clear to send Frame checksum Hybrid controlled channel access Initiator aggregate control Medium access controller Modulation and coding MCS feedback MAC header MPDU MRAD MRQ MSDU NAV Non-Agg PPDU QoS MAC protocol data unit Multi-receiver aggregate descriptor MCS request MAC service data unit Network allocation vector Non-Aggregate PHY protocol data unit Quality of Service RAC RDG

RDL RDR RTS TXOP Responder aggregate control Reverse direction grant Reverse direction limit Reverse direction request Ready to send Transmit opportunity HCCA IAC MAC MCS MFB MHDR Submission Slide 93 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 MAC Backup Submission Slide 94 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 MAC Challenges in HT Environment HT requires an improvement in MAC Efficiency HT requires effective Rate Adaptation

HT requires Legacy Protection 80% MAC Efficiency 70% 60% 50% Basic Rate 54 Mbps 40% Basic Rate 6 Mbps 30% 20% 10% 0% 0 5 10 15 20 25 Packet Size (KB) Submission Slide 95 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Periodic Multi-Receiver Aggregation Submission Slide 96

Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Following Packet Descriptor (FPD) Protocol Spoofed Spoofed PLCP Length Spoofed Note, duration value of EIFS-DIFS which is NOT included in the spoofed PLCP Length FPD Protocol Spoofed Length Length / Rate Submission Spoofed Length Length / Rate Slide 97 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 Channel Selection Support 20/40 MHz and 20 MHz operating modes of whole BSS In 20/40 MHz mode, all legacy PPDUs are 20 MHz, all HT PPDUs exchanged between HT STA are either 40

MHz or 20 MHz depending on operating mode and STA capability Channel selection constraints Partial overlap between HT systems is not allowed Legacy STAs are only allowed in the control sub-channel except in 20 MHz-base managed mixed mode An HT AP responds to changes in environment to maintain channel selection constraints Submission Slide 98 Syed A on Muj March 20 05 doc.: IEEE 802.11-04/888r9 MAC Architecture Key Closed Loop Link Adaptation 802.11n 802.11n Indirect Rate Adaptation based on Missing Ack Transmit Opportunity RDG 802.11e 802.11 Aggregate Exchange Sequences IAC/ RDR/ RAC RDG EDCA

HCCA DCF RTS/CTS/Data/ACK exchange Sequences Link Management Channel Access Methods Frame Exchange Sequences Aggregation Format Aggregation Block Ack MRAD / IAC / RAC Submission RTS / CTS / DATA / Ack Slide 99 MPDU Formats Syed A on Muj

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