NTU Confidential 1 Introduction of TGnSync 802.11n proposal Speaker:Zih-Yin Ding Professor: Tzi-Dar Chiueh September 27 th, 2004.

NTU Confidential 1

Introduction of TGnSync 802.11n proposaIntroduction of TGnSync 802.11n proposall

Speaker:Zih-Yin DingProfessor: Tzi-Dar Chiueh

September 27th, 2004

2

OutlineOutline

• Introduction of 802.11nIntroduction of 802.11n– MotivationMotivation– Functional RequirementFunctional Requirement– Primary Schedule Milestones

• Introduction of the TGnSync 802.11n ProposalIntroduction of the TGnSync 802.11n Proposal– PHY Enhancement Techniques– Operation ModesOperation Modes– Packet formatPacket format

• ConclusionConclusion• ReferenceReference

3

MotivationMotivation• High throughput drives the demand for

802.11n

[3]

4

Project Authorization Project Authorization Request (PAR)Request (PAR)

• 802.11n PAR scope:– To define standardized modifications to

both the 802.11 physical layers (PHY) and the 802.11 Medium Access Control Layer (MAC) so that modes of operation can be enabled that are capable of much higher throughputs, with a maximum throughput of at least 100Mbps, as measured at the MAC data service access point (SAP).

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Functional RequirementFunctional Requirement

FR1: Link throughput of 100Mbps at the top of the MAC SAP

FR2: 20MHz channel (per device)FR3: Supports 5GHz bands FR4, 5: 802.11a & .11g backwards compatibility FR6: AP controls the support for legacy STA

FR7: Supports .11e QOS

FR8: Spectral efficiency of at least 3 bps/Hz for the PSDU

FR9: Compliance to PAR

6

PrimaryPrimary Schedule Schedule MilestonesMilestones

Issue First Letter Ballot on Draft 1.0 July 2005

Issue First Sponsor Ballot Mar 2006

Complete Sponsor ballot - accepted by ExCom Nov 2006

Publish Mar 2007

NTU Confidential 7

An Introduction of An Introduction of the Proposal of TGnSyncthe Proposal of TGnSync

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TGnSyncTGnSync

• Some of TGnSync members include: Agere Systems Inc. Atheros Communications Inc. Cisco Systems, Inc. Intel Corporation Marvell Semiconductor, Inc. Nokia Corporation Nortel Networks Corporation Panasonic (Matsushita Electric Industrial Co. Ltd.) Royal Philips Electronics N.V. Samsung Electronics Co. Ltd. SANYO Electric Co. Ltd. Sony Corporation Toshiba Corporation

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PHY PHY EnhancementEnhancement Techniques Techniques (1/2)(1/2)

• High Throughput Enhancement involved– Spatial Multiplexing using MIMO– Increasing the channel bandwidth – Reducing the guard interval overhead– Increasing the coding rate

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PHY PHY Enhancement Enhancement Techniques Techniques (2/2)(2/2)

• Link Robustness Enhancement Techniques– Keep the client low cost and low power – Transmitter beamforming– Advanced transmitter beamforming techniques

• Water-filling concept• Unequal power ratios and different choice of modulatio

n-coding schemes on various spatial streams– Advanced channel coding

• Low density parity code (LDPC)• CC+RS

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PHY FeaturesPHY Features

• MIMO evolution of 802.11 OFDM PHY – up to 4 spatial streams

• 20 and 40MHz channels • 2x2 architecture – 140Mbps in 20MHz and

315Mbps in 40MHz• Preamble allows seamless interoperability

with legacy 802.11a/g• Optional enhancements

– Transmit beamforming with negligible overhead at the client

– Advanced channel coding techniques (RS, LDPC)– 1/2 guard interval (i.e. 400ns)– 7/8 coding rate

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MIMO Transmission MIMO Transmission ModesModes

• Basic MIMO Mode (Mandatory)– Nss=NTX

• Basic MIMO with TX Beamforming (optional) : BF-MIMO

– Nss<= NTX

– All spatial stream have identical MCS and power level• Advanced MIMO with TX Beamforming (optional): AB

F-MIMO– Nss<= NTX

– MCS and power level in each spatial stream can be different

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TX Arch: Spatial Division TX Arch: Spatial Division MultiplexingMultiplexing

e.g.e.g. 2 Spatial streams with 2 TX antennas 2 Spatial streams with 2 TX antennas (mandatory)(mandatory)

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TX Arch: Spatial Division TX Arch: Spatial Division MultiplexingMultiplexing

e.g.e.g. 2 Spatial streams with 2 Spatial streams with 33 TX antennas ( TX antennas (optionaloptional))C

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BandBand Design for 20 and 40 MH Design for 20 and 40 MHzz

-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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Motivation for 40MHz Motivation for 40MHz ChannelizationChannelization

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

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e A

ir T

hro

ug

hp

ut

(Mb

ps)

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

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Basic MCS SetBasic MCS Set

Modulation 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 13.5, 27, 45.5, 54

QPSK 1/2 12, 24, 36, 48 27, 54, 81, 108

QPSK 3/4 18, 35, 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

* Optional short GI (400ns) increases rates by 11.1%

NTU Confidential 18

Packet formatPacket format

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Packet format Packet format (2 spatial stream)(2 spatial stream)

20M

Hz

AN

T_1

LegendL- Legacy HT- High ThroughputSTF Short Training FieldLTF Long Training FieldSIG Signal Field

L-STF L-LTF L-SIG HT-SIG HT-DATA

Legacy Compatible Preamble HT-specific Preamble

HTSTF

HTLTF-1

HTLTF-2

•The HT-SIG include Length, MCS, Advanced options and CRC(cyclic redundancy check)

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HT PHT Packetacket Detection Detection

• Auto-detection scheme on HT-SIG– Q-BPSK modulation – Invert the polarity

of the pilot tones

L-STF L-LTF L-SIG HT-SIG

L-STF L-LTF L-SIG

orLegacyDATA

Legacy Compatible Preamble

-1 +1

+1

-1

BPSK

Q-BPSK

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HT Training FieldsHT Training FieldsHT 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

• HT-STF– 2nd AGC measurement is used to fine-tune MIMO

reception• HT-LTF

– Used for MIMO channel estimation– Additional frequency or time alignment– The number of HT-LTF= The number of spatial stream

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ConclusionConclusion

• The proposal proposed by TGnSync is introduced.

• From this proposal, we can find some techniques that may be introduced in High Through WLAN are – MIMO technique, wider channel bandwidth, reduc

ed guard interval, increased coding rate and advanced coding

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ReferenceReference[1] TGnSync Website: http://www.tgnsync.org[2] TGnSync Present slide- DCN:11-04-0888-02-000n[3] http:// snrc.stanford.edu/events/industry- seminar/spring03/slides/t

aekon.pdf

NTU Confidential 24

Backup slidesBackup slides

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20/40 MHz 20/40 MHz InteroperabilityInteroperability

• 20 MHz PPDU into a 40 MHz receiver– The active 20 MHz sub-channel is detected

using energy measurement of the two sub-channels

– Inactive tones at the FFT output (i.e. 64 out of 128) are not used

• 40 MHz PPDU into a 20 MHz receiver– One 20 MHz sub-channel is sufficient to

decode the L-SIG and the HT-SIG

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Advanced techniqueAdvanced technique

• Beamforming

– To increase the antenna gain in the direction of an intended receiver

– One method to calculate V involves SVD of the channel transfer matrix H

– Channel state information is needed– Reciprocity is assumed – RF calibration is needed

11 SSSSNxTxT

NNN xVy

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Mandatory v.s. optionalMandatory v.s. optional

• Mandatory: 20MHz, spatial multiplexing• Optional: Beamforming, 20MHz or 40MHz cha

nnel bandwidth, LDPC

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Packet format in 20MHzPacket format in 20MHz20

MH

z

AN

T_1

LegendL- Legacy HT- High ThroughputSTF Short Training FieldLTF Long Training FieldSIG Signal Field

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

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Overview of key mandatory Overview of key mandatory featuresfeatures

• The WWiSE proposal’s mandatory modes are:– 2 transmit antennas– 20 MHz operation– 135 Mbps maximum PHY rate– 2x1 transmit diversity modes, 20 MHz– Mixed mode preambles enabling on-the-air legacy compati

bility– Efficient greenfield preambles – no increase in length over l

egacy– Enhanced efficiency MAC mechanisms– All components based on enhancement of existing COFDM P

HY

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Overview of key optional Overview of key optional featuresfeatures

• The WWiSE proposal’s optional modes are:– 3 and 4 transmit antennas– 40 MHz operation– Up to 540 Mbps PHY rate– 2x1, 3x2, 4x2, 4x3 transmit diversity modes– Advanced coding: Rate-compatible LDPC code