March 12, 2009 doc.:IEEE 802.11-09/0303 Effect of SDMA in 802 · March 12, 2009 doc.:IEEE...

doc.:IEEE 802.11-09/0303March 12, 2009

Effect of SDMA in 802.11acA thAuthors:

Name Affiliations Address Phone email Naoki Honma NTT Corp. 1-1 Hirkarinooka, Yokosuka-shi,

Kanagawa, Japan, 239-0847+81-46-859-5107 [email protected]

Kentaro Nishimori NTT Corp. 1-1 Hirkarinooka, Yokosuka-shi, Kanagawa, Japan, 239-0847

+81-46-859-8266 [email protected]

Riichi Kudo NTT Corp. 1-1 Hirkarinooka, Yokosuka-shi, Kanagawa Japan 239-0847

+81-46-859-3140 [email protected] Kanagawa, Japan, 239 0847

Yasushi Takatori NTT Corp. 1-1 Hirkarinooka, Yokosuka-shi, Kanagawa, Japan, 239-0847

+81-46-859-8596 [email protected]

Submission NTT CorporationSlide 1

doc.:IEEE 802.11-09/0303March 12, 2009

Contents

1. Introduction1. Introduction

1 Evaluation of SDMA effect1. Evaluation of SDMA effect

1 Effect of time variant channel1. Effect of time-variant channel

1 C l i1. Conclusion


doc.:IEEE 802.11-09/0303March 12, 2009

Introduction• In PAR of TGac, more than 1 Gbps throughput must

be achieved with multiple STAs.

• MIMO-SDMA can be a key technology to reach this y gyvery high throughput.

• The feasibility of MIMO-SDMA is evaluated in an actual indoor office environment which can be aactual indoor office environment, which can be a typical scenario in 802.11ac.


doc.:IEEE 802.11-09/0303March 12, 2009

Contents






doc.:IEEE 802.11-09/0303March 12, 2009

Measurement SetupAP

D/AMapper Up convIFFT D/AMapper Up convIFFTer

#1

STA 1 STA 4

D/A

D/A

D/A

Mapper

Mapper

M

Up conv.

Up conv.

Up convIFFT

IFFT

IFFT

D/A

D/A

D/A

Mapper

Mapper

M

Up conv.

Up conv

Up conv.IFFT

IFFT

IFFTmul

tiple

xe #2

#3STA-1

STA 2

STA-4D/A

D/A

Mapper Up conv

Up conv.IFFT

IFFT

D/A

D/A

Mapper Up conv.

Up conv.

IFFT-W

eigh

t m

IFFTS/P #4

MapperMapper

STA-3STA-2.

Inter -

D/AMapper

Conv.

.

Inter -Inter -

IFFTTx-

#16

Tx-

Up conv

16 16 MIMO h l t d d t ectio

n FFT

FFT oder

mapperDe-

De-ectio

n FFT

FFT oder

mapperDe-

mapperDe-

-conv.Down

Down AGC/

AGCA/D

#1

#2

leaver encoderleaverleaver data

•16x16 MIMO channel measurements and data transmission at 5GHz with 20MHz BW were conducted at a typical office room in NTT lab.

min

g de

te FFT

FFT

SDM

dec

o mapper

mapperDe-

Dmin

g de

te FFT

FFT

SDM

dec

o mapper

mapperDe-

D

S/P-conv.

-conv.Down

D

A/D

AGC

AGCA/D

#3

#4•Downlink performances were evaluated for up to 8 STAs in static and time variant channels.

Tim

FFT

S

lDe-inter

mapperDe-Ti

m

FFT

S

De-inter

mapperDe-

ViterbiD

-conv.Down AGC

A/D#4

Rx-d


0leaverDec.data

doc.:IEEE 802.11-09/0303D l d M t S t

March 12, 2009Developed Measurement System

Transmit antennas

Rx site1.7 m

Transmitters (16)

Receivers (16)

Tx site

( )

Received antennas

LNAs0.7 m


doc.:IEEE 802.11-09/0303March 12, 2009

Transmission ParametersSignal format based on IEEE802.11n is used.

Number of antennas (Tx) 16 (Element spacing: 1λ) N b f t (R ) 2 3 4 (El t i 0 5λ)

g

Number of antennas (Rx) 2, 3, 4 (Element spacing: 0.5λ)Transmit power Max. 6 dBm (Total) Packet length 100 coded OFDM signalPacket length 100 coded OFDM signalNumber of subcarriers 48 ( Pilot 4) Pilot signal 6 20 34 48Pilot signal 6, 20, 34, 48Bit error Less than 10-7

Bandwidth 20 MHzBandwidth 20 MHzSampling rate 40 MHzModulation scheme QPSK, 16QAM, 64QAM,Modulation scheme QPSK, 16QAM, 64QAM,

256QAM, and 1024QAMCoding rate 1/2, 2/3, 3/4, 5/6, and 7/8


Cod g ate / , /3, 3/ , 5/6, a d 7/8

doc.:IEEE 802.11-09/0303March 12, 2009

Achieved over 42.8 bits/s/Hz (@SNR=30 dB)

STA-1(9.8 bit/s/Hz (196Mbps), R=5/6)

STA-2(11 bit/s/Hz (220Mbps), R=7/8) ( ( p ) )

STA-4(11 bit/s/Hz (220Mbps), R=7/8)

STA-3(11 bit/s/Hz (220Mbps), R=7/8) ( ( p ), )( ( ) )


doc.:IEEE 802.11-09/0303Transmission Rate vs Number of Receiving Antennas

March 12, 2009Transmission Rate vs. Number of Receiving Antennas

in a Static Office Environment60

50

60SDMA (NT =16, NT =NR x NU) (16x16x1)

(16x4x4)(16x8x2)

SDMA (NT =8, NT =NR x NU)

40

50

bit/s

/Hz] TDMA (NT =16, NT > NU) (16x2x8)

TDMA (NT = NR)

(16x4x4)

(16x8x1) (12 12 1)

( T , T R U)

30rate

[b (12x12x1)

(8x2x4)(8x4x2) - Spectrum efficiency strongly

depends on the number of20

mis

sion

(8x8x1)

(16x4x1)

(8x2x4) depends on the number ofantennas at AP.-Even with 2 or 4 antennas at

10 SNRave.

= 31dBTran

sm

(N x N x N )(4x4x1)

( 6 ) Even with 2 or 4 antennas ateach STA, 20bit/s/Hz (NR=8)and 40bit/s/Hz (NR=16) were

00 4 8 12 16

N b f i i t (N )

(NT x NR x NU) ( R )attained.


Number of receiving antennas (NR)

doc.:IEEE 802.11-09/0303March 12, 2009

Transmission Rate per STA vs. Number of STAs

12 MIMO-TDMATransmission rate becomess/

Hz]

(16x2)(SNR = 30 dB)

8

10 Rs / U.

TA [b

it/s

MIMO-SDMA(16x2)

U: Number of users

6

8

MIMO-SDMA yields aper S

TA

(16x2)

4

yhigher transmission ratethan MIMO-TDMA, whenon

rate

MIMO-TDMA11n(2x2)

2 the number of users isincreased.

nsm

issi

o (2x2)

11a(1x1)01 2 3 4 5 6 7 8

N b f

Tran 11a(1x1)


Number of users

doc.:IEEE 802.11-09/0303March 12, 2009

Contents






doc.:IEEE 802.11-09/0303March 12, 2009

Evaluation in time variant channel

Tx : 8 ele.h = 2 5m

Rx : 2ele.h 0 7

D/A Up-conv.

AP h = 2.5m h = 0.7m

D/AD/A

Up-conv.Up-conv.D/A

D/Ap

AGCA/DDown-conv

Up-conv.

D/ATCP-IP

Up-conv.A/DAGCA/D

Down-conv.

Down-conv.

Preamble generatorSTA

TCP-IPChannel estimator


doc.:IEEE 802.11-09/0303March 12, 2009

Environment for the measurements

1 2

CSI is obtained fromAP to P1~P8.

26AP

354

H1(t)~ H8(t) (0 ≤ t ≤ 100msec)

26 m7

86

8 1) Without personin front of each STA

2) Wi h40 m Height: 3 m

2) With personin front of each STA

AP position STA position DeskWallPartition 1Pillar Partition 2


p p

doc.:IEEE 802.11-09/0303March 12, 2009

Capacity in time variant channel (1) Without person in front of each STA

Eigen-mode transmission （MIMO-TDMA）

Without person in front of each STA.

MIMO-SDMA （2-STAs, 2-streams）（4-STAs, 2-streams）

（8-STAs, 1-stream）

5 0

6 0

ec/H

z]

- MIMO-SDMA attains 2.8-

3 0

4 0

rate

[bit/

se

2.8fold

fold improvement overMIMO-TDMA.

MIMO-SDMA

2 0

3 0

evab

le b

it r fold - Slight fall off in ABR is

observed with MIMO-MIMO TDMA

0

1 0

0 2 0 4 0 6 0 8 0 1 0 0

Ach

i

SDMA.MIMO-TDMA


0 0 0 6 0 8 0 1 0 0D e l a y t i m e [ m s e c ]

doc.:IEEE 802.11-09/0303March 12, 2009

Capacity for time variant channel (2) With person in front of each STAWith person in front of each STA.

Eigen-mode transmission （MIMO-TDMA）MIMO-SDMA （2-STAs, 2 streams）（4 STAs, 2 streams）（8 STAs, 1 stream）

5 0

6 0

c/H

z] - MIMO-SDMA attains2 5 2 8 f ld i t

3 0

4 0

ate

[bit/

sec

2.8fold

2.5fold

2.5-2.8 fold improvementover MIMO-TDMA.

Sli ht f ll ff i2 0

3 0

vabl

e bi

t ra fold fold

MIMO-SDMA- Slight fall off inachievable bit rate isobserved with MIMO

0

1 0

Ach

iev

MIMO-TDMAobserved with MIMO-SDMA.


0 2 0 4 0 6 0 8 0 1 0 00D e l a y t im e [ m s e c ]

doc.:IEEE 802.11-09/0303March 12, 2009

Contents






doc.:IEEE 802.11-09/0303March 12, 2009

Conclusions• SDMA can be important technology in TGac

– 40 bits/s/Hz frequency utilization efficiency was achieved i h 16 @ AP d 2 4 @ MTwith 16 antennas @ AP and 2 or 4 antennas @ MT.

– 20 bits/s/Hz frequency utilization efficiency was achieved with 8 antennas @ AP and 2 or 4 antennas @ MTwith 8 antennas @ AP and 2 or 4 antennas @ MT.

• Time-variant channel was measured: indoor environmentTime variant channel was measured: indoor environment– Small effect of the human body on the bit-rate was observed.– The bit-rate deterioration can be alleviated by reducing the number of y g

streams.

• TGac channel models may consider time-variant characteristics with spatially multiplexed STAs.


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