Download - TGn Sync Complete Proposal
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 1
doc.: IEEE 802.11-04/888r7
Submission
TGn Sync Complete Proposal
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.
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Date: 2005-01-15
Author
Name Company Address Phone Email
Syed Aon Mujtaba Agere Systems
555 Union Blvd.,Allentown, PA 18109, USA
+1 610 712 6616 [email protected]
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Submission
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]
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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[email protected] IncorporatedJohn Ketchum
[email protected] Mitsubishi Electric CorporationJin Zhang
[email protected] SemiconductorPeter Loc
[email protected] Philips ElectronicsPen Li
[email protected] ElectronicsPaul Feinberg
[email protected] NetworksOsama Aboul-Magd
[email protected] van Waes
[email protected] Philips ElectronicsMonisha Gosh
[email protected] CorporationMasahiro Takagi
[email protected] SystemsMary Cramer
[email protected] SystemsLuke Qian
[email protected] for Infocomm ResearchLi Yuan
[email protected] Kobayashi
[email protected] Electronics Co LtdJon Rosdahl
[email protected] CorporationJohn Sadowsky
[email protected] Philips ElectronicsJorg Habetha
[email protected] CorporationJoe Pitarresi
[email protected] Philips ElectronicsJob Oostveen
[email protected] CommunicationsJeff Gilbert
[email protected] Jokela
January 2005
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[email protected] IncorporatedSubra Dravida
[email protected] IncorporatedSanjiv nanda
[email protected] Electric Co LtdYasuhiro Tanaka
[email protected] CorporationYasuhiko Tanabe
[email protected] SystemsXiaowen Wang
[email protected] CommunicationsWon-Joon Choi
[email protected] Stolpman
[email protected] CorporationTsuguhide Aoki
[email protected] CorporationTomoya Yamaura
[email protected] CorporationTomoko Adachi
[email protected] Philips ElectronicsTeik-Kheong (TK) Tan
[email protected] CorporationTakushi Kunihiro
[email protected] Fukugawa
[email protected] Electronics Co LtdTaekon Kim
[email protected] for Infocomm ResearchSumei Sun
[email protected] CorporationStephen Shellhammer
[email protected] CommunicationsSheung Li
[email protected] Electric Co LtdSeigo Nakao
[email protected] Phiips ElectronicsRonald Rietman
January 2005
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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]
January 2005
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Abstract This document describes the TGn Sync
complete proposal submission to IEEE 802.11 TGn
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New TGn Sync Members Infocomm Mitsubishi Electric Corporation Qualcomm Incorporated Sharp Corporation Tohoku University Wavebreaker/ATcrc Wavion
January 2005
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TGn Sync Mission Statement Develop a scalable architecture to support
present and emerging applications
Foster a broad industry representation across market segments
January 2005
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Broad Industry Representation OEM / System Vendors
■ Cisco■ Mitsubishi Electric■ Nokia■ Nortel■ Panasonic■ Samsung■ Sanyo■ Sharp■ Sony■ Toshiba■ Wavebreaker/ATcrc■ Wavion
Semi Vendors■ Agere■ Atheros■ Intel■ Marvell■ Philips■ Qualcomm
PC
Enterprise
Consumer Electronics
Asia
Pac
ific
/ Eur
ope
/ Nor
th A
mer
ica
Semiconductor
Handset
Public Access
Academia Academia
■ Infocomm■ Tohoku University
January 2005
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Scalable Architecture across several dimensions
Performance Over Time
Market Segments
Regulatory Domains North America
EuropeAsia Pacific
140 / 243Mbps315Mbps 630Mbps
ResidentialEnterprisePublic AccessPortable Devices
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… And a well-defined Core
Mandatory Features:■ Two antennas■ 20 / 40MHz
140 / 243 Mbps
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PHY Summary of TGn Sync Proposal Mandatory Features:
■ 1 or 2 Spatial Streams■ 20MHz and 40MHz* channelization■ 1/2, 2/3, 3/4, and 7/8 channel coding rates■ RX assisted Rate Control■ Optimized Interleaver for 20 & 40MHz■ 400ns & 800ns Guard Interval■ Full & seamless interoperability with a/b/g
Optional Features:■ Transmit Beamforming■ Low Density Parity Check (LDPC) Coding
• Completed merger process with LDPC partial proposals ■ support for 3 or 4 spatial streams
*Not required in regulatory domains where prohibited.
140Mbps in 20MHz
243Mbps in 40MHz
NEW
NEW
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MAC Summary of TGn Sync Proposal Mandatory Features:
■ MAC level aggregation ENHANCED■ RX assisted link adaptation■ QoS support (802.11e)■ MAC header compression■ Block ACK compression■ Legacy compatible protection■ 20/40 MHz channel management
Optional Features:■ Bi-directional data flow■ MIMO RX Power management
January 2005
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PHY
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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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 7/8■ Support for RX assisted Rate Control■ Guard Interval: 400ns and 800ns
Optional robustness & throughput enhancement:■ Transmit beamforming■ Advanced coding (LDPC)■ SDM with 3 or 4 spatial streams
Max Mandatory rate in 20MHz = 140 Mbps Max Mandatory rate in 40MHz = 243 Mbps
(with 2x2 architecture using 2 spatial streams)
with the option to scale to 630Mbps
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Modifications to PHY Arch after San Antonio
Optimized specification for interleaver for both 20 MHz and 40 MHz channelizations
Completed the merger process with LDPC partial proposals■ Detailed specification of LDPC encoding can
be found in 889r2 (TGn Sync Technical Specification)
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Scalable PHY Architecture
Open Loop SDM
RX assisted Rate Control
2 Spatial Streams
20 MHz
Regulatory Constraints
40 MHz
Low Cost & Robust
140 Mbps 243 Mbps
Robustness Enhancement
Closed Loop TX BF
4 Spatial Streams
ThroughputEnhancement
Conv. Coding LDPC
Robustness Enhancement
630 Mbps
Mandatory Optional
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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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
■ Due to per spatial stream training, no change is needed at the RX to support optional techniques
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Parameters in Link Adaptation
Basic MIMO Beamformed MIMO
Stream Control No YesRate (MCS) Control Yes Yes (per
stream)GI selection Yes YesTX Per-Tone Steering Matrix No YesPer Stream Power Loading No Yes
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Mandatory PHY Features
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TX Arch: Spatial Division Multiplexinge.g. 2 Spatial streams with 2 TX antennas
Cha
nnel
Enc
oder
Pun
ctur
er
FrequencyInterleaver
ConstellationMapper
iFFTModulator
insertGI
windowsymbols
Pilots
Preamble
Scr
ambl
edM
PD
U
FrequencyInterleaver
ConstellationMapper
iFFTModulator
insertGI
windowsymbols
Pilots
Preamble
Spa
tial p
arse
r
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Tone Design for 20 and 40 MHz
-58 -6 +6 +58-64 +63
-53 -25 -11 +11 +25 +53
-2 +2-32 +32
Legacy 20 MHz inLower Sub-Channel
Legacy 20 MHz inUpper Sub-Channel
-26 +26-1 +1-21 -7 +7 +21
20 MHz:• Identical to 802.11a• 64 point FFT• 48 data tones• 4 pilot tones
40 MHz:• 128 point FFT• 108 data tones• 6 pilot tones
Tone Fill in the Guard Band
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Syed Aon Mujtaba, Agere Systems, et. al.
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‡ Duplicate format, BPSK R = ½ provides 6 Mbps for 40 MHz channels½ GI applies to all data rates in 20MHz
Scalable Basic MCS SetModulation Code Rate
Data Rates 20 MHz (Mbps)(1,2,3,4 spatial streams)
Data Rates 40 MHz (Mbps)(1,2,3,4 spatial streams)
BPSK 1/2 6, 12, 18, 24 6‡, 13.5, 27, 45.5, 54
QPSK 1/2 12, 24, 36, 48 27, 54, 81, 108
QPSK 3/4 18, 36, 54, 72 40.5, 81, 121.5, 162
16 QAM 1/2 24, 48, 72, 96 54, 108, 162, 216
16 QAM 3/4 36, 72, 108, 144 81, 162, 243, 324
64 QAM 2/3 48, 96, 144, 192 108, 216, 324, 432
64 QAM 3/4 54, 108, 162, 216 121.5, 243, 364.5, 486
64 QAM 7/8 63, 126, 189, 252 141.7, 283.5, 425.2, 567
64 QAM 7/8 with ½ GI 70, 140, 210, 280 157.5, 315, 472.5, 630
Mandatory MCSOptional MCS
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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HT-PPDU Format in 20MHz20
MH
z
AN
T_1
LegendL- Legacy HT- High ThroughputSTF Short Training FieldLTF Long Training FieldSIG Signal Field
Legacy CompatibleCan be decoded by anylegacy 802.11a or g compliant device for interoperability
L-STF L-LTF L-SIG HT-SIG HT-DATA
L-STF L-LTF L-SIG HT-SIG HT-DATA
Legacy Compatible Preamble HT-specific Preamble
HTSTF
HTLTF-1
HTLTF-2
20M
Hz
AN
T_2
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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HT-PPDU Format in 40MHz
AN
T_1
AN
T_2
40M
Hz
40M
Hz
Legacy Compatible Preamble HT-specific Preamble
HTSTF
HTLTF-1
HTLTF-2
L-STF L-LTF L-SIG HT-SIG
HT-DATA
DuplicateL-STF
DuplicateL-LTF
Dup.L-SIG
DuplicateHT-SIG
L-STF L-LTF L-SIG HT-SIG
HT-DATA
DuplicateL-STF
DuplicateL-LTF
Dup.L-SIG
DuplicateHT-SIG
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Spoofing
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■ max MSDU length = 2304 Bytes spoofing duration up to ~3 msec
L-STF L-LTF L-SIG HT-SIG HT LTF HT LTF Data
Legacy RATE and LENGTH fields => Packet Length in OFDM Symbols
HTSTF
January 2005
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HT PPDU Detection
Auto-detection 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
L-STF L-LTF L-SIG HT-SIG
L-STF L-LTF L-SIG
orLegacyDATA
Legacy Compatible Preamble
January 2005
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MIMO AGC
Tone interleaving the L-STF leads to perfect decorrelation■ 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
L-STF L-LTF L-SIG HT-SIG HT-DATA
single spatial stream multiple spatial streams
powermeasurement
AGC locked
*
1
_ _TXN
j ji jii
Power RX Power TX h h
Accurate measurement of MIMO channel power
requires uncorrelated STFs
*( ) ( ) 0i jE STF f STF f
January 2005
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Power Fluctuation of L-STF w.r.t Data
-7 -6 -5 -4 -3 -2 -1 0 1 2 30
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
x = Power fluctuation of AGC setting w.r.t. data power (dB)
STF = Tone InterleavedSTF = Cyclic Delay
CD
F(x)
Power fluctuation with tone interleaving is within 1dB of the data power
Data power
Introduce a dedicated STF for MIMO that is tone interleaved
Reduces 1 bit in the ADC cost & power savings
2x2, TGn Channel DSNR = 30dB
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Power Fluctuation of HT-LTF w.r.t. Data
-10 -8 -6 -4 -2 0 2 40
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
x = Power fluctuation of HT-LTF w.r.t. data (dB)
CD
F(x)
HT-LTF = Tone Interleaved
HT-LTF = Walsh + Cyclic Delay
2x2, TGn Channel DSNR = 30dB
Data power
Large deviation of HT-LTF power wrt data power will result in higher channel estimation error
HT-LTF should be tone interleaved
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Tone Interleaved HT Training Fields
HT-STF■ 2nd AGC measurement is used to fine-tune MIMO reception
HT-LTF■ Used for MIMO channel estimation■ Additional frequency or time alignment
HT SIG 2 LTS1 LTS2 DATA
DATA
DATA
HT LTF
HT SIG 2
HT SIG 2
HTSTS
HTSTS
HTSTS
LTS1 LTS2
LTS1 LTS2
LTS1 LTS2
LTS1 LTS2
LTS1 LTS2
HT LTFHTSTF
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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
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Legacy Interoperability of PreambleCross Correlation with STS
0
0.001
0.002
0.003
0.004
0.005
0.006
0.007
0.008
0.009
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
Abs
olut
e Va
lue
of C
ross
Cor
rela
tion
Cross Correlation with STS
0
0.001
0.002
0.003
0.004
0.005
0.006
0.007
0.008
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
Abs
olut
e Va
lue
of C
ross
Cor
rela
tion
Cross-correlation of L-STS (TGn Sync)
Cross-correlation of L-STS (WWiSE)
Period = 800ns
Period = 400ns
Potential issues with cross-correlation receivers with WWiSE preamble
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Transmitted Signal
Tx2
Tx1
L-STF L-LTF L-SIG L-DAT
L-STF(400n) L-LTF(3100n) L-SIG(3100n) L-DAT(3100n)
Tx1
Tx2
L-STF
.11a preamble (as used by TGn Sync)L-LTF L-SIG L-DATTx1
WWiSE preamble
Packetgenerator
TGnChannel model
Tx1
Tx2
C simulator Agilent E4438C
Single inputsingle output
signal generator
January 2005
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Submission
Measurement Setup
Compare the RATE and LENGTH
TGn simulator
WLAN cardunder test
Aeropeek NX
Agilent E4438CEnhanced Signal Generator (ESG)
Wireless
5.19GHz10cm apartOmni transmit antenna
RATELENGTH RATE
LENGTH
January 2005
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WWiSE preamble performance with Autocorrelation RX
Laboratory Test with a legacy autocorrelation RX
"Autocorrelation Vendor" (Channel D)
1.0E-03
1.0E-02
1.0E-01
1.0E+00
-30 -25 -20 -15 -10 -5 0
Relative Tx power [dBm]
Mea
sure
d SI
G F
ER
Legacy w/o CDDLegacy w/ CDD (400nsec)
January 2005
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Submission
WWiSE preamble performance with Crosscorrelation RX
FER Floor!FER Floor!
Performance limitation with a WWiSE preamble
"Cross Correlation Vendor" (Channel model D)
1.0E-03
1.0E-02
1.0E-01
1.0E+00
-30 -25 -20 -15 -10 -5 0Relative Tx power [dBm]
Mea
sure
d SI
G F
ER
Legacy w/o CDDLegacy w/ CDD (400nsec)
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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 Sync’s decision to use a
100% backwards compatible legacy preamble
January 2005
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Submission
TGn Sync enhanced interleaver11a Bit interleaver,
PermutationOperation 1
parser
FrequencyRotation
SISO (11a/g)
MIMO 2x11a Bit interleaver,
PermutationOperation 1
11a Bit interleaver,PermutationOperation 2
11a Bit interleaver,PermutationOperation 2
11a Bit interleaver,PermutationOperation 1
11a Bit interleaver,PermutationOperation 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
2nd stream 22 22 22 58 58 58
3rd stream 11 11 29 29
Freq
uenc
y R
otat
ion
4th stream 33 87
1st Spatial Stream
2nd, 3rd, or 4th Spatial Stream
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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0 5 10 15 20 25 30 35 4010
-2
10-1
100
2x2x20MHz, Channel B-NLOS, MCS 8-15
SNR, dB
PE
R
Original interleaverUpdated interleaver
Enhanced Interleaver Results1 to 2dB gain
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Submission
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
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Dual Stream Performance2 vs 4 Pilots with 2 streams, 2x2, E NLOS
1.E-03
1.E-02
1.E-01
1.E+00
5 10 15 20Average SNR [dB]
Pac
ket E
rror
Rat
e
2 streams, BPSK, 1/2, 2 pilots
2 streams, BPSK, 1/2, 4 pilots
1 dB
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Submission
Single Stream Performance2 vs 4 Pilots with single stream, 2x2, E NLOS
1.E-03
1.E-02
1.E-01
1.E+00
5 10 15 20Average SNR [dB]
Pac
ket E
rror
Rat
e
1 stream, BPSK, 1/2, 2 pilots
1 stream, BPSK, 1/2, 4 pilots
3.5 dB
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Submission
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
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 45
doc.: IEEE 802.11-04/888r7
Submission
Importance of Rate Feedback and Stream Control
Throughput is maximized if there is rapid convergence to a good choice of stream count and MCS
■ Initial MCS/stream selection ■ Ongoing tracking and optimization
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
■ Under some circumstances, e.g. pairwise spoofing, TX must adhere to MFB
Important for Basic MIMO, Spatial Spreading and Beamforming
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 46
doc.: IEEE 802.11-04/888r7
Submission
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
TX RX
MRQ payload in PHY sounding packet
Full H matrix
Number of streams and coding rate carried in MFB
h11Ant1
Ant2
h12
h21
h22
2
1
2212
2111
hh
hhhh
H
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 47
doc.: IEEE 802.11-04/888r7
Submission
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:■ allows MCS selection, but not stream count
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 48
doc.: IEEE 802.11-04/888r7
Submission
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
0
20
40
60
80
100
120
140
160
180
200
10 15 20 25 30 35 40 45 50
SNR [dB]
MA
C th
roug
hput
[Mbp
s]
TxBf 2%SS closed loop 2%SS open loop 2%TxBf 10%SS closed loop 10%SS open loop 10%
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 49
doc.: IEEE 802.11-04/888r7
Submission
MSDU Delay CDFTarget PHY PER = 10%
SS open loop 10% PER
SS closed loop 10% PER
TxBf closed loop 10% PER
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 50
doc.: IEEE 802.11-04/888r7
Submission
Is 40MHz Mandatory? Both 20 MHz & 40 MHz capabilities are
mandatory■ With exceptions due to regulatory requirements
Capability depends on regulatory domain (just like channelization plans):■ 20/40 MHz capable devices■ 20 MHz only capable devices
Both types of devices are fully interoperable
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 51
doc.: IEEE 802.11-04/888r7
Submission
20/40 MHz Operation
20/40 MHz Region(e.g. in US/Europe)
20 MHz Region(e.g. in Japan)
20/40 MHz Capable Device
(e.g. in US/Europe)40 MHz Operation
(20 MHz Operation)20 MHz Operation;40 MHz disabled
20 MHz only Capable Device(e.g. in Japan)
Seamless 20 MHz operation in a 40
MHz BSS20 MHz Operation
Where Used
Where Bought
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 52
doc.: IEEE 802.11-04/888r7
Submission
Why 40MHz is Mandatory?
0
20
40
60
80
100
120
140
160
180
200
220
240
260
0 5 10 15 20 25 30 35
SNR (dB)
Ove
r the
Air
Thro
ughp
ut (M
bps)
2x2-40 MHz
4x4-20 MHz
2x2-20 MHz w/ short GI
2x3-20 MHz w/ short GI
2x2 – 40 MHz• Only 2 RF chains => Cost effective & low power• Lower SNR at same throughput => Enhanced robustness
Basic MIMO MCS setNo impairments1000 byte packetsTGn channel model B
Sweet spot for 100Mbps top-of-MAC
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 53
doc.: IEEE 802.11-04/888r7
Submission
20/40 MHz Interoperability 40 MHz PPDU into a 40 MHz receiver
■ Get 3dB processing gain – duplicate format allows combining the legacy compatible preamble and the HT-SIG in an MRC fashion
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■ 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
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 54
doc.: IEEE 802.11-04/888r7
Submission
Optional PHY Features
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 55
doc.: IEEE 802.11-04/888r7
Submission
Seamless Arch Extension for TX BFe.g. 2 Spatial Streams across 3 Transmit Antennas
Cha
nnel
Enc
oder
Pun
ctur
er
FrequencyInterleaver
ConstellationMapper
Pilots
HT LTF
Scr
ambl
edM
PD
U
FrequencyInterleaver
ConstellationMapper
Pilots
Spat
ial S
teer
ing
Mat
rix
Per Spatial Stream Processing:HT-LTF & HT-Data undergo same spatial transformation iFFT
Mod.insert
GI win
dow
iFFTMod.
insertGI
iFFTMod.
insertGI
win
dow
win
dow
Spa
tial P
arse
r
HT LTF
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 56
doc.: IEEE 802.11-04/888r7
Submission
0
20
40
60
80
100
120
140
160
0 5 10 15 20 25 30 35
SNR (dB)
Ove
r-th
e-A
ir Th
roug
hput
(Mbp
s)
2x2 - SDM
2x3 - SDM
2x2 - Advanced BF
3x2 - Advanced BF
4x2 - Advanced BF
Why introduce TX Beamforming?
1000 byte packetsNo impairment20MHz, channel D
4 TX-antenna AP 2 RX-antenna client ~10 dB gain of 4x2-ABF over 2x2-SDM => cost effective client
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 57
doc.: IEEE 802.11-04/888r7
Submission
WWiSE proposal can not support Tx Beamforming
Problem■ WWiSE channel estimation requires smoothing
algorithms■ Channel smoothing cannot be applied with MIMO
Beamforming
Problem■ WWiSE GF structure does not allow omni-directional
transmission of SIG-N■ Result: Hidden node problems
ref: doc. 11-05/1635r1
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 58
doc.: IEEE 802.11-04/888r7
Submission
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
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 59
doc.: IEEE 802.11-04/888r7
Submission
Example: 4x4, Channel D
-20
-15
-10
-5
0
5
10
15
-10 -8 -6 -4 -2 0 2 4 6 8 10Frequency (MHz)
Sing
ular
Val
ue (d
B)
0.75
0.80
0.85
0.90
0.95
1.00
-10 -8 -6 -4 -2 0 2 4 6 8 10
Frequency (MHz)
abs(
rho
)
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 60
doc.: IEEE 802.11-04/888r7
Submission
Optional LDPC Capacity approaching FEC
■ Iterative decoding superior performance Strong performance in AWGN and fading channels
■ Typically 2-4 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
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 61
doc.: IEEE 802.11-04/888r7
Submission
0
20
40
60
80
100
120
140
0 5 10 15 20 25 30 35
SNR (dB)
Thro
ughp
ut (M
bps)
Conv.
LDPC
Basic MIMO MCS SetNo Impairments1000 byte packets2x2, NLOS Channel EConstraint PER < 2%
Benefit of LDPC Coding
4 dB of coding gain
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 62
doc.: IEEE 802.11-04/888r7
Submission
PHY Summary Mandatory Rate of 140Mbps in 20MHz:
■ 2 Spatial Streams■ 7/8th rate coding■ 400ns Guard Interval■ RX assisted Rate Control
Low Cost & Robust Throughput Enhancement:■ Scalable to 243 Mbps in 40MHz
Optional Robustness/Throughput Enhancements:■ LDPC Coding■ Transmit Beamforming■ Scalable to 630Mbps with 4 spatial streams in 40MHz
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 63
doc.: IEEE 802.11-04/888r7
Submission
MAC
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 64
doc.: IEEE 802.11-04/888r7
Submission
Scalable MAC Architecture
BASELINE MAC•Robust Aggregation•QoS Support (802.11e)•Rx assisted link adapt.
ADDITIONAL EFFICIENCY•Header Compression•Multi-Receiver Aggregation•Bi-Directional Data Flow•BA Enhancements
LEGACY INTEROP.•Long NAV•Pairwise Spoofing•Single-Ended Spoofing
CHANNEL MANAGEMENT•20/40 MHz Modes
Robust&
ScalableMAC
Architecture
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 65
doc.: IEEE 802.11-04/888r7
Submission
Modifications to MAC Arch November 2004 to January 2005
■ Added A-MSDU aggregation
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 66
doc.: IEEE 802.11-04/888r7
Submission
Baseline MAC Features
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 67
doc.: IEEE 802.11-04/888r7
Submission
A-MPDU Aggregation StructureM
PD
UH
eade
r
Leng
thC
RC
MP
DU
Pay
load
FC
S
MP
DU
Hea
der
Leng
thC
RC
MP
DU
Pay
load
FC
S
MP
DU
Hea
der
Leng
thC
RC
MP
DU
Pay
load
FC
S
MP
DU
Del
imite
r
MP
DU
PSDU
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
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 68
doc.: IEEE 802.11-04/888r7
Submission
A-MSDU Aggregation Structure
FrameControl Dur / ID Address
1Address
2Address
3Seq
ControlQoS
ControlAddress
4A-
MSDU FCS
Subframe 1 Subframe 2 Subframe n...
SubframeHeader MSDU Pad
DA SA Len
0-2304 B 0-3 B14 B
6B 6B 2B
Carrier MPDU
•Efficient Structure
•MSDUs of the same TID can be aggregated
•MSDUs with differing SA/DA can be aggregated
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 69
doc.: IEEE 802.11-04/888r7
Submission
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)
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 70
doc.: IEEE 802.11-04/888r7
Submission
Dat
a M
PDU
Agg
PPD
UD
ata
MPD
U
Dat
a M
PDU
Initi
ator
Tx
Activ
ityPH
Y Tx
MAC
Tx
Res
pond
er T
x Ac
tivity
PHY
TxM
AC T
x
Non
-agg
PPD
UBl
ock
Ack
Basi
c ra
teno
n-ag
gR
TS
Basi
c ra
teno
n-ag
gC
TS
Dat
a M
PDU
Agg
PPD
UD
ata
MPD
U
Dat
a M
PDU
Non
-agg
PPD
UBl
ock
Ack
Dat
a M
PDU
Dat
a M
PDU
Dat
a M
PDU
Dat
a M
PDU
Dat
a M
PDU
Dat
a M
PDU
Implicit BlockAck Protocol
RTS/CTSProtocol
Dat
a M
PDU
Dat
a M
PDU
Basic Aggregate Exchange
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 71
doc.: IEEE 802.11-04/888r7
Submission
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
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 72
doc.: IEEE 802.11-04/888r7
Submission
RX Assisted Link Adaptation Protocol
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 73
doc.: IEEE 802.11-04/888r7
Submission
Features Providing Additional Efficiency
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 74
doc.: IEEE 802.11-04/888r7
Submission
Reverse Direction Data Flow Gives an opportunity for a responder to
transmit data to an initiator during the initiator’s TXOP
Aggregates data with response control MPDUs
Reduces Contention Effective in increasing TCP/IP performance
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 75
doc.: IEEE 802.11-04/888r7
Submission
Agg
PP
DU
Initi
ator
Tx
Act
ivity
PH
Y T
xM
AC
Tx
Res
pond
er T
x A
ctiv
ityP
HY
Tx
MA
C T
x
Bas
ic ra
teno
n-ag
gIA
C M
PD
U(R
TS+
RD
L)
Bas
ic ra
teno
n-ag
gR
AC
MP
DU
(CTS
+RD
R)
Dat
a M
PD
U
Agg
PP
DU
Dat
a M
PD
U
BA
MP
DU
Agg
PP
DU
Blo
ck A
ck
Dat
a M
PD
UD
ata
MP
DU
Dat
a M
PD
U
RA
C M
PD
U
IAC
MP
DU
(RD
G)
Reverse DirectionProtocol
BA
R M
PD
U
Dat
a M
PD
UD
ata
MP
DU
IAC
MP
DU
RD
GD
urat
ion
Dat
a M
PD
U
Dat
a M
PD
U
Reverse Direction Protocol
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 76
doc.: IEEE 802.11-04/888r7
Submission
Enhanced BA Mechanism
Aggregation frameM
D D1 D2 D3 D4Initiator
ResponderCompressed
BA
SIFS
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.
Compressed Non-Frag Num MSDU TID
1 – 128 Frame
ControlDuration/
ID RA TA BA Control
BA Starting Seq. Control BlockAckBitmap FCS
BA Bitmap size is fixed through BA setup.
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 77
doc.: IEEE 802.11-04/888r7
Submission
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
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 78
doc.: IEEE 802.11-04/888r7
Submission
Multiple ResponsesIAC:
OffsetDuration
IAC:Offset
Duration
IAC:Offset
Duration
Initiator’s PPDU
Response from RA2
Response from RA 3
Duration 1
Duration 3
Offset 1
Duration 2E
nd o
f PP
DU Offset 2
Offset 3
Response from RA1
MRA contains multiple IAC for ■ One per response■ At most one per receiver
IAC specifies response offset and duration
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 79
doc.: IEEE 802.11-04/888r7
Submission
Legacy Interoperability and Channel Management
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 80
doc.: IEEE 802.11-04/888r7
Submission
Protection Mechanisms LongNAV
■ 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
Pairwise Spoofing■ 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
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 81
doc.: IEEE 802.11-04/888r7
Submission
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
RAC(CTS)
IAC(RTS) Agg
Agg
Agg
Agg
CF-End
NAV Value
NAV Value
Nom
inal
End
of T
XO
P
Nav Timer Non-Zero
Resetsthe
NAV
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 82
doc.: IEEE 802.11-04/888r7
Submission
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
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 83
doc.: IEEE 802.11-04/888r7
Submission
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
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 84
doc.: IEEE 802.11-04/888r7
Submission
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 MHz-capable HT STA
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 85
doc.: IEEE 802.11-04/888r7
Submission
20 MHz-base Managed Mixed Mode
ch_a (control)
CTSself/Bcn
CF-End
tch_b (extension)
Bcn/ICB
CF-End
CF-End
tRCB
NAV
NAV
NAVNAV
NAVch_a
NAVch_b
NAVch_a+ch_b
20MHz
40MHz20MHz
CarrierSense(CS)
CS
CS
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 86
doc.: IEEE 802.11-04/888r7
Submission
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
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 87
doc.: IEEE 802.11-04/888r7
Submission
Selected System CC PerformanceCC# Name Result HCCA
2x2x20 2x2x40
CC3 List of goodput results for usage models 1, 4 and 6.
SS1 (Mbps) 84 84
SS1 + 87 135
SS4 90 160
SS4 + 98 189
SS6 66 66
SS6 + 85 166
CC18 HT Usage Models SupportedNon-QoS(Measured aggregate throughput / offered aggregate throughput)
SS1(Mbps/ratio)
31/1.0 31/1.0
SS4 81/18 151.033 SS6 21/1.0 21/1.0
CC19 HT Usage Models Supported
(number of QoS flows that meet their QoS requirements)
SS1 17 of 17 17 of 17
SS4 18 of 18 18 of 18
SS6 39 of 39 39 of 39
CC58 HT Spectral Efficiency bps/Hz 5.3 5.94
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 88
doc.: IEEE 802.11-04/888r7
Submission
Value of MAC FeaturesFeatur
e Value Condi-tion
S1 (Mbps) S4 (Mbps) S6 (Mbps)
TGn bis TGn bis TGn bis
Pairwise spoofing
(vs LongNav)6-
10%Long NAV 70.25 - 71.57 - 49.92 -Pairwise Spoofing 77.52 - 78.64 - 53.06 -
Enhanced BA
2 - 12%
- 73.30 - 92.40 - 63.80 -+ 75.40 - 103.3 - 65.10 -
Reverse Direction
5 - 36%
- 82.08 87.26 90.60 126.91 62.56 66.96
+ 83.85* 94.67 123.2
8 141.0
2 66.00 96.24
26 -56%
+Periodic RDR - - 142.1
2 160.1
2 - -
Header Compressio
n1-6%
- 82.08 87.26 90.60 126.91 62.56 66.96
+ 83.39* 87.98 96.79 127.9
8 62.72 68.56
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 89
doc.: IEEE 802.11-04/888r7
Submission
Comparison of TGnSync and WWiSE System Simulation results
References:11-04-892r3 – TGnSync MAC results11-04-877r8 – WWiSE MAC results
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 90
doc.: IEEE 802.11-04/888r7
Submission
System Simulation Results
“+” scenarios have all BE traffic offered load increased to 100 mbps (s-1) or 30 mbps (s-4,6)“*” - 1 QOS flow missed PLR targetThese results will improve when advanced beamforming, MRMRA and periodic RDR options are added
Blue = TGnSyncBlue = TGnSyncBlack = WWiSEBlack = WWiSE
CC# Name Scenario EDCA HCCACC3 Goodput 1 7575/67/67 8484/83/83
1+ 9595/71/71 135135/121/1214 142142/124/124
** 160160/178/1784+ 164164/127/127 189189/186/1866 6666/64/64 6666/65/65
6+ 8888/70/70 166166/105/105
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 91
doc.: IEEE 802.11-04/888r7
Submission
System Simulation Results
TGnSync MAC results significantly outperform WWiSE
MAC Goodput: EDCA
020406080
100120140160180
1+ 4+ 6+
TGnSync
WWiSE
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 92
doc.: IEEE 802.11-04/888r7
Submission
MAC Efficiency
Blue = TGnSyncBlue = TGnSyncBlack = WWiSEBlack = WWiSE
CC# Name Scenario EDCA HCCA
CC24 MAC Efficiency
11 3232/27/27 3232/33/331+1+ 3636/28/28 5151/47/4744 5050/47/47 5656/67/67
4+4+ 5858/48/48 6767/70/7066 2424/25/25 2424/25/25
6+6+ 3232/27/27 6262/40/40
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 93
doc.: IEEE 802.11-04/888r7
Submission
MAC Efficiency
TGnSync MAC efficiency significantly outperforms WWiSE
MAC Efficiency: EDCA
0
10
20
30
40
50
60
70
1+ 4+ 6+
TGnSync
WWiSE
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 94
doc.: IEEE 802.11-04/888r7
Submission
MAC Summary Baseline Features
■ MAC Level A-MPDU and A-MSDU Aggregation■ QoS Support (802.11e)■ Receiver assisted link adaptation
Additional MAC Efficiency■ Header Compression■ Multi-Receiver Aggregation■ Bi-Directional Data Flow■ Enhanced Block ACK
Legacy Compatible Protection Mechanisms■ Long NAV■ Pairwise Spoofing■ Single Ended Spoofing
Scalable Channel Management■ 20/40 MHz Operating Modes
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 95
doc.: IEEE 802.11-04/888r7
Submission
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
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Modifications since Nov 2004
Optimized■ interleaver specification for 20
MHz and 40 MHz channelizations
Completed merger process with LDPC partial proposals
Added■ A-MSDU aggregation
PHY MAC
January 2005
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Scalable Architecture across several dimensions
Performance Over Time
Market Segments
Regulatory Domains North America
EuropeAsia Pacific
140 / 243Mbps315Mbps 630Mbps
■ MRMRA• Efficiency for isochronous clients (VoIP)
■ MRAD • Power saving support for portable devices
■ Reverse direction • Higher network efficiency for bulk data transfer
Enterprise■ Lower 802.11n rates
• Range extension and robustness for handsets
■ MRMRA • Power savings and robustness for handset
mobility
Portable Devices
■ Tx beamforming • Extended range for Hot Spot
■ RX assisted Link Adaptation• Higher throughput in congested
environments
Public Access
Residential Tx Beamforming
■ Coverage throughout the home Reverse direction
■ Increased efficiency for gaming
ResidentialEnterprisePublic AccessPortable Devices
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Key Features Scalable PHY & MAC Architecture 20 and 40 MHz channels – fully interoperable Data rate scalable to 630 Mbps Legacy interoperability – all modes Robust preamble Transmit beamforming Robust frame aggregation Bi-directional data flow Fast link adaptation
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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GlossaryCRC Cyclic Redundancy Check MPDU MAC protocol data unit
Agg Aggregate MRADMulti-receiver aggregate descriptor
BA Block Ack MRQ MCS requestBAR Block Ack Request MSDU MAC service data unitBSS Basic service set NAV Network allocation vectorCHDATA Compressed header data Non-Agg Non-AggregateCTS Clear to send PPDU PHY protocol data unitFCS Frame checksum QoS Quality of Service
HCCAHybrid controlled channel access RAC Responder aggregate control
IAC Initiator aggregate control RDG Reverse direction grantMAC Medium access controller RDL Reverse direction limitMCS Modulation and coding RDR Reverse direction requestMFB MCS feedback RTS Ready to sendMHDR MAC header MPDU TXOP Transmit opportunity
January 2005
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MAC Backup
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Submission
MAC Challenges in HT Environment HT requires an improvement in MAC Efficiency HT requires effective Rate Adaptation HT requires Legacy Protection
0%
10%
20%
30%
40%
50%
60%
70%
80%
0 5 10 15 20 25
Packet Size (KB)
MAC
Effi
cien
cy
Basic Rate 54 Mbps
Basic Rate 6 Mbps
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Submission
MAC Header CompressionOctets: 2 2 6 6 6 1 1 2 4
Frame Control Duration Address 1 Address 2 Address 3 HID Reserved QoS
Control FCS
MAC Header
1
Octets: 2 2 1 1 n 4
Frame Control
Sequence Control HID Reserved Payload Data FCS
Compressed Header
1
MHDR MPDU carries repeated Header fields
CHDATA MPDU refers to previous MHDR MPDU■ HID field ties the two together■ Context only within current aggregate
January 2005
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Periodic Multi-Receiver Aggregation
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Following Packet Descriptor (FPD) Protocol
Agg
PPD
U
Initi
ator
Tx
Activ
ityPH
Y Tx
MAC
Tx
Res
pond
er T
x Ac
tivity
PHY
TxM
AC T
x
Dat
a M
PDU
FPDProtocol
Spoofed PLCP Length
Spoofed Length
Note, duration value ofEIFS-DIFS which is NOTincluded in the spoofed
PLCP LengthIAC
MPD
U(F
PD:L
engt
h)
Dat
a M
PDU
Dat
a M
PDU
Agg
PPD
UBl
ock
ACK
RAC
MPD
U(M
FB:R
ate)
Agg
PPD
U
IAC
MPD
U
Spoofed
Dat
a M
PDU
Dat
a M
PDU
Non
-Agg
PPD
UBl
ock
ACK
Non
-Agg
PPD
UIA
C M
PDU
(FPD
:Len
gth)
Non
-Agg
PPD
UR
AC M
PDU
(MFB
:Rat
e)
Spoofed Length
Spoofed
Length / Rate Length / Rate
Dat
a M
PDU
Dat
a M
PDU
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 105
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MIMO Power Management Timed Receive Mode Switching (TRMS) allows a STA to
operate with only 1 of its receive chains enabled most of the time
■ Switch to fully enabled when the STA transmits a frame■ Hold-on timer keeps the STA fully enabled for a known period of
time Good for bursty traffic
■ reduced latency compared to other methods of power saving
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 106
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Submission
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
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 107
doc.: IEEE 802.11-04/888r7
Submission
MAC Architecture
DCFHCCA
RDG
Aggregation
Aggregate ExchangeSequences
EDCA
RTS/CTS/Data/ACKexchange Sequences
MRAD / IAC / RAC /MHDR / CHDATA RTS / CTS / DATA / Ack MPDU Formats
Aggregation Format
ChannelAccess
MethodsFrame
ExchangeSequences
LinkManagement
Indirect RateAdaptation based on
Missing AckClosed Loop Link Adaptation
Transmit Opportunity802.11n
802.11e
802.11
Key
Block Ack
IAC/RAC
RDR/ RDG
802.11n
MHDR/CHDATA
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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PHY Backup Slides
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
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Spatial Stream Tone Interleaving1 SpatialStream
2 SpatialStreams
3 SpatialStreams
4 SpatialStreams
• 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
January 2005
Syed Aon Mujtaba, Agere Systems, et. al.
Slide 110
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Submission
HT-SIG Contents
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
MCS (6 bits)HTLENGTH (18 bits)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
SIGNAL TAIL (6 bits)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
MCS (6 bits)HTLENGTH (18 bits)
AD
V C
OD
ING
(1 b
it)
NU
MB
ER
HT-
LTF
(2 b
its)
SC
RA
MB
LER
INIT
(2 b
its)
CRC (8 bits) SIGNAL TAIL (6 bits)
HT-SIG1
Transmit Order
SO
UN
DIN
G P
AC
KE
T (1
bit)
SH
OR
T G
I (1
bit)
AG
GR
EG
ATE
(1 b
it)
20/4
0 B
W (
1 bi
t)
RE
SE
RV
ED
(1 b
it)
HT-SIG2