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Introduction of TGnSync 802.11n proposal. Speaker:Zih-Yin Ding Professor: Tzi-Dar Chiueh September 27 th , 2004. Outline. Introduction of 802.11n Motivation Functional Requirement Primary Schedule Milestones Introduction of the TGnSync 802.11n Proposal PHY Enhancement Techniques - PowerPoint PPT Presentation
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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
8
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
9
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
10
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
11
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
12
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
13
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)
Ch
an
ne
l En
cod
er
Pu
nct
ure
r
FrequencyInterleaver
ConstellationMapper
iFFTModulator
insertGI
windowsymbols
Pilots
Preamble
Scr
am
ble
dM
PD
U
FrequencyInterleaver
ConstellationMapper
iFFTModulator
insertGI
windowsymbols
Pilots
Preamble
Sp
atia
l pa
rse
r
14
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
ha
nn
el E
nco
de
r
Pu
nct
ure
r
FrequencyInterleaver
ConstellationMapper
Pilots
HT LTF
Scr
am
ble
dM
PD
U
FrequencyInterleaver
ConstellationMapper
Pilots
Sp
atia
l Ste
erin
g (
TX
Be
am
form
ing
), o
rO
rth
og
on
al S
pa
tial S
pre
ad
ing
with
Cyc
lica
l De
lay
iFFTMod.
insertGI
win
do
w
iFFTMod.
insertGI
iFFTMod.
insertGI
win
do
ww
ind
ow
Sp
atia
l Pa
rse
r
HT LTF
15
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
r th
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
17
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
19
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)
20
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
21
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
22
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
23
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
25
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
26
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
27
Mandatory v.s. optionalMandatory v.s. optional
• Mandatory: 20MHz, spatial multiplexing• Optional: Beamforming, 20MHz or 40MHz cha
nnel bandwidth, LDPC
28
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
29
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
30
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