May 2009 doc.:IEEE 802.11-09/0543r0

Measured Channel Capacity and AoD Estimation for Multi-User MIMOEstimation for Multi User MIMO

ScenariosName Affiliations Address Phone emailByung-Jae Kwak ETRI 138 Gajeongno, Yuseong-gu,

Daejeon, 305-700, Korea +82-42-860-6618 bjkwak@etri.re.kr

Jae Joon Park ETRI 138 Gajeongno, Yuseong-gu,

Daejeon, 305-700, Korea +82-42-860-3958 jjpark@etri.re.kr

Myung Don Kim ETRI 138 Gajeongno, Yuseong-gu,

Daejeon, 305-700, Korea+82-42-860-6178 mdkim@etri.re.kr

Daejeon, 305 700, KoreaMinho Cheong ETRI 138 Gajeongno, Yuseong-gu,

Daejeon, 305-700, Korea +82-42-860-5635 minho@etri.re.kr

Inkyung Choi ETRI 138 Gajeongno, Yuseong-gu,

Daejeon, 305-700, Korea +82-42-860-5242 ikchoi@etri.re.kr

Hyun Kyu Chung ETRI 138 Gajeongno, Yuseong-gu, Daejeon, 305-700, Korea

+82-42-860-6140 hkchung@etri.re.kr Daejeon, 305 700, Korea

Sok-Kyu Lee ETRI 138 Gajeongno, Yuseong-gu, Daejeon, 305-700, Korea

+82-42-860-5919 sk-lee@etri.re.kr

Gregory Breit Qualcomm 5775 Morehouse Dr., San Diego, CA

+1-858-651-3809 gbreit@qualcomm.com

Hemanth Sampath Qualcomm 5775 Morehouse Dr., San Diego, CA

+1-858-658-1848 hsampath@qualcomm.com CA

Submission Byung-Jae Kwak et al., ETRISlide 1

I t d tiMay 2009 doc.:IEEE 802.11-09/0543r0

IntroductionDuring the TGac channel model addendum document discussion in Vancouver meeting, there was interest in studying the AoD spectrum variation as a function of client location and orientationorientation.

This presentation describes measurement results performed at p pETRI to address the following issues:

Sensitivity of SDMA channel capacity to Transmit and Receive antenna orientationorientation.Variation of SDMA DL AoD spectrum as a function of client location.

Submission Byung-Jae Kwak et al., ETRISlide 2

M t S iMay 2009 doc.:IEEE 802.11-09/0543r0

Measurement Scenario1 Tx AP (8 antennas) and 6 Rx STAs (2 antennas each)(8 a e as) a d 6 S s ( a e as eac )Antenna Configurations

Uniform Linear Antenna: 8x2Tx Ant Orientation: -30o ~ +30o in 10o stepsRx Ant Orientation: -180o ~ +180o in 30o steps

Measurement SiteOffice environment1st floor, bldg. #7, ETRI3 LOS, 3 NLOS

Submission Byung-Jae Kwak et al., ETRISlide 3

May 2009 doc.:IEEE 802.11-09/0543r0

Floor Map of the Meas rement SiteFloor Map of the Measurement Site

1

TxRx

13m

Concretewall

28m

(LoS)

(LoS)

3

4concrete wall concrete pillar

13m

18m

15m11m

(LoS)(NLoS)

steel wall

Tx antorientation:-30o~30o in 10o steps

6

5 partition

desks

steelpartition

(NLoS)

(NLoS)Rx ant orientation:180o 180o i 30o t

Submission Byung-Jae Kwak et al., ETRISlide 4

-180o~180o in 30o steps

May 2009 doc.:IEEE 802.11-09/0543r0

Th M t SitThe Measurement Site

T

Tx antenna height = 2mRx antenna height = 90cm

Tx

Tx Ant System gTx Ant System

LOS Non-LOS

R

Tx

Rx

Rx

Submission Byung-Jae Kwak et al., ETRISlide 5

May 2009 doc.:IEEE 802.11-09/0543r0

Sensitivity to Antenna Orientation (NLOS)Sensitivity to Antenna Orientation (NLOS)Sensitivity to Antenna Orientation (NLOS)Sensitivity to Antenna Orientation (NLOS)Capacity is calculated by using MMSE post-SINR

Random AoD shifts all MU MIMO user Random AoA shifts per MU MIMO user

4 STAs: STA #3 (NLOS), #4 (LOS), #5 (NLOS), #6 (NLOS)Tx ant orientation: -30° ~ +30° in 10° steps (case1 ~ case7)Rx ant orientation: -180° ~ +180° in 30° steps (case1 ~ caseC)

0.8

0.9

1Random AoD shifts all MU-MIMO user

case1case2case3case4 0.8

0.9

1Random AoA shifts per MU-MIMO user

case1case2case3case4

0.5

0.6

0.7

CD

F

case5case6case7

0.5

0.6

0.7

CD

F

case5case6case7case8case9casea

0.2

0.3

0.4

0.2

0.3

0.4caseacasebcasec

20 22 24 26 28 30 32 34 36 38 400

0.1

Capacity [bps/Hz]20 22 24 26 28 30 32 34 36 38 40

0

0.1

Capacity [bps/Hz]

Tx ant orientation: 30° +30° Rx ant orientation: 180° 180°

Submission Byung-Jae Kwak et al., ETRISlide 6

Tx ant orientation: -30° ~ +30°Rx fixed at case 1

Rx ant orientation: -180° ~ 180°Rx fixed at case 1

May 2009 doc.:IEEE 802.11-09/0543r0

Sensitivity to Antenna Orientation (LOS)Sensitivity to Antenna Orientation (LOS)Sensitivity to Antenna Orientation (LOS)Sensitivity to Antenna Orientation (LOS)Capacity is calculated by using MMSE post-SINR

Random AoD shifts all MU MIMO user Random AoA shifts per MU MIMO user

4 STAs: STA #1 (LOS), #2 (LOS), #3 (NLOS), #4 (LOS)Tx ant orientation: -30° ~ +30° in 10° steps (case1 ~ case7)Rx ant orientation: -180° ~ +180° in 30° steps (case1 ~ caseC)

0.8

0.9

1Random AoD shifts all MU-MIMO user

case1case2case3case4 0.8

0.9

1Random AoA shifts per MU-MIMO user

case1case2case3case4

0.5

0.6

0.7

CD

F

case5case6case7

0.5

0.6

0.7

CD

F

case5case6case7case8case9caseA

0.2

0.3

0.4

0.2

0.3

0.4caseAcaseBcaseC

20 22 24 26 28 30 32 34 36 38 400

0.1

Capacity [bps/Hz]20 22 24 26 28 30 32 34 36 38 40

0

0.1

Capacity [bps/Hz]

Tx ant orientation: 30° +30° Rx ant orientation: 180° 180°

Submission Byung-Jae Kwak et al., ETRISlide 7

Tx ant orientation: -30° ~ +30°Rx fixed at case 1

Rx ant orientation: -180° ~ 180°Tx fixed at case 1

May 2009 doc.:IEEE 802.11-09/0543r0

Sensitivity to Antenna Orientation: ConclusionsSensitivity to Antenna Orientation: ConclusionsSensitivity to Antenna Orientation: ConclusionsSensitivity to Antenna Orientation: ConclusionsSDMA channel capacity is sensitive to the Tx and Rx antenna orientations

Capacity is more sensitive to the orientation of the Tx antenna array than that of the individual Rx client arrays. For example,

NLOS:32 ±3 bps/Hz when Tx ant. orientation changed (Δθ = 60o)31±2 bps/Hz when Rx ant orientation changed (Δθ = 360o)31 ±2 bps/Hz when Rx ant. orientation changed (Δθ = 360o)

Note: The absolute values of the capacities are not relevant. We h ld b f d h d/should be focused on the trend/pattern, etc

The above result indicates that TGac MU-MIMO channel models need to incorporate AoD variation across clients, to be realistic.

Submission Byung-Jae Kwak et al., ETRISlide 8

May 2009 doc.:IEEE 802.11-09/0543r0

AoD Estimation from Linear Array MeasurementsAoD Estimation from Linear Array Measurements

Th A D t i ti t d f li t bThe AoD spectrum is estimated from linear array measurements by the following method:

Assume:Antenna array length = NAntenna separation (relative to wavelength) = (d/λ)• Phase vector A(θ) = [1 ej2π(d/λ)sinθ ej4π(d/λ)sinθ ej(N-1)2π(d/λ)sinθ ]• Phase vector A(θ) = [1 ej ( ) ej ( ) …… ej( ) ( ) ]

where θ = AoDReceived channel vector for the j-th time-domain tap = hj

The AoD spectrum is obtained by plotting 20log10(|| hj A(θ)||) vs. θ.

For the purposes of this presentation, the AoD has been averaged across all time-domain taps.

Submission Byung-Jae Kwak et al., ETRISlide 9

May 2009 doc.:IEEE 802.11-09/0543r0

A D S t t E h STA (1/3)

Tx antenna orientation: case 7

AoD Spectrum at Each STA (1/3)

Tx antenna orientation: case 7Rx antenna orientation: case 1

90AoD Spectrum -- User 1

90AoD Spectrum -- User 2

30

60120

150

Ant1Ant2

30

60120

150

Ant1Ant2

-10 0180 0

gula

r Pow

er [d

B]

-10 0180 0

gula

r Pow

er [d

B]

-150 -30

Ang

-150 -30

Ang

-120

-90

-60

Angle [deg]

-120

-90

-60

Angle [deg]

Submission Byung-Jae Kwak et al., ETRISlide 10

User 1 User 2

May 2009 doc.:IEEE 802.11-09/0543r0

A D S t t E h STA (2/3)AoD Spectrum at Each STA (2/3)

Tx antenna orientation: case 7Tx antenna orientation: case 7Rx antenna orientation: case 1

90AoD Spectrum -- User 3

90AoD Spectrum -- User 4

30

60120

150

Ant1Ant2

30

60120

150

Ant1Ant2

-10 0180 0

gula

r Pow

er [d

B]

-10 0180 0

gula

r Pow

er [d

B]

-150 -30

Ang

-150 -30

Ang

-120

-90

-60

Angle [deg]

-120

-90

-60

Angle [deg]

Submission Byung-Jae Kwak et al., ETRISlide 11

User 3 User 4

May 2009 doc.:IEEE 802.11-09/0543r0

A D S t t E h STA (3/3)

Tx antenna orientation: case 7

AoD Spectrum at Each STA (3/3)

Tx antenna orientation: case 7Rx antenna orientation: case 1

90AoD Spectrum -- User 5

90AoD Spectrum -- User 6

30

60

90

120

150

Ant1Ant2

30

60

90

120

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Ant1Ant2

-10 0180 0

ular

Pow

er [d

B]

-10 0180 0

ular

Pow

er [d

B]

-150 -30

Ang

-150 -30

Ang

-120

-90

-60

Angle [deg]

-120

-90

-60

Angle [deg]

Submission Byung-Jae Kwak et al., ETRISlide 12

User 5 User 6

May 2009 doc.:IEEE 802.11-09/0543r0

V i ti f A D t C l iVariation of AoD spectrum: Conclusions

Measurements suggest considerable AoD variation across clientsMeasurements suggest considerable AoD variation across clients. Note: AoD range of approx ±30o was suggested for NLOS clusters in the TGac channel model addendum document.

Further analysis and measurements are underway to characterise AoD variation, on a cluster-by-cluster basis.

We recommend that the TGac channel model addendum document use a “TBD” value for AoD range, until the analysis is completed. va ue o o a ge, u t t e a a ys s s co p eted.

Submission Byung-Jae Kwak et al., ETRISlide 13