doc.: IEEE 802.11-09/0161r1

Submission

Doc.:IEEE 802.11-09/0537r0May 11th, 2009

Slide 1

Measured Doppler Frequency in Indoor Office Environment

Date: 2009-05-11

Name Affiliations Address Phone email

Kentaro Nishimori NTT Corporation Hikarino-oka Yokosuka-shi Japan

+81 468 59 8266

nishimori.kentaro@lab.ntt.co.jp

Yasushi Takatori NTT Corporation Hikarino-oka Yokosuka-shi Japan

+81 468 59 8596

taktori.yasushi@lab.ntt.co.jp

Wataru Yamada NTT Corporation Hikarino-oka Yokosuka-shi Japan

+81 468 59 3321

Wataru-y@ansl.ntt.co.jp

Authors:

doc.:IEEE 802.11-09/0537r0

doc.: IEEE 802.11-09/0161r1

Submission

Doc.:IEEE 802.11-09/0537r0

Purpose of this measurement• Although there is a model for Doppler frequency in IEEE802.11n, we could not find other reliable papers for Doppler frequency effect in indoor environment. • Since SDMA performance may be vulnerable to the channel variation compared to single user MIMO, Doppler frequency should

be carefully considered in IEEE802.11ac.

We conducted measurements to show actual Doppler frequencyeffects in a typical office room. The followings are the measured two scenarios.(1) Influence of fluorescent light: Measured environment is shown in page5-6(2) Comparison between LOS and NLOS environment: Measured environment is shown in page7-8.

doc.: IEEE 802.11-09/0161r1

Submission

Doc.:IEEE 802.11-09/0537r0

Measurement equipment

10MHz L.O.

Signal Generator

Transmitter site

Wireless Communication Analyzer

(Base band real-timespectrum analyzer)

Receiver site

LNA

Sleeve antenna

(Omni-directional)

Sleeve antenna

(Omni-directional)

doc.: IEEE 802.11-09/0161r1

Submission

Doc.:IEEE 802.11-09/0537r0

Measurement parameter

• Frequency 4.85GHz

• Signal CW

• Transmit power 0 dBm

• Number of FFT 1024

• Frequency span 100 Hz

• Antenna height (Mes.1) 1.7m (Tx), 0.7m (Rx)

• Antenna height (Mes.2) 2.7m (Tx), 0.7m (Rx)

doc.: IEEE 802.11-09/0161r1

Submission

Doc.:IEEE 802.11-09/0537r0

Measurement place (A)

B

C

A

E

F

D

H

I

G

#1

#16

#1

#16

12.1 m

17.6 m4.3 mShelf (2m) Shelf (2m)

Desk (0.8m)

Tx Rx

Partition

Partition

Desk (0.8m)

Desk (0.8m)

2.5 m 2.5 m

Height = 3 m

In this measurement, the receive antenna is located

at the position B.

Influence of fluorescent light is evaluated.

doc.: IEEE 802.11-09/0161r1

Submission

Doc.:IEEE 802.11-09/0537r0

Photo of measurement place (A)

Transmit antenna

Receive

antenna

There is no people between the transmit and receive antennas.

doc.: IEEE 802.11-09/0161r1

Submission

Doc.:IEEE 802.11-09/0537r0

Measurement place (B)

女子更衣室

男子更衣室

書庫 /倉庫ｽﾍﾟｰｽ

円卓 円卓円卓

円卓円卓円卓

P P P P P

＋専用 FAX

脇机+ 書庫書庫

COPY

P

P

COPY COPY FAX FAX冷・ﾚﾝｼﾞ TV

ﾄﾞｱﾄﾞｱ

ﾄﾞｱ

ﾄﾞｱ

ﾄﾞｱ

ﾄﾞｱ

ﾄﾞｱ

第

2

会議室

第

1

会議室 第

3

会議室

たな　たなしょが しょが

しょが

ﾄﾞｱ紙置場

LANスペース

ﾄﾞｱﾄﾞｱ

富士山側

Tx2

Rx1Rx1

Window

LOSNLOS

LOS (Line of sight) and NLOS (Non LOS) are assumed.

doc.: IEEE 802.11-09/0161r1

Submission

Doc.:IEEE 802.11-09/0537r0

Photo of measurement place (B)

Tx2(1.2m)-Rx1(0.75m)

Transmit antenna

Spectrum

analyzer

0.7m2.7m

Receive

antenna

Sometime, people walk

between the transmitter

and receiver.

doc.: IEEE 802.11-09/0161r1

Submission

Doc.:IEEE 802.11-09/0537r0

In our measurement, the measured Doppler frequency was not affected by the fluorescent condition, i.e. light was on or off. As can be seen in the slide, the bell shape curve fits to the measured Doppler frequency while fd is around 0.10Hz but not 1Hz

Influence of fluorescent light

-140

-120

-100

-80

-60

-40

-20

-25 -20 -15 -10 -5 0 5 10 15 20 25

Rec

eive

d P

ower

[dB

]

Frequency [Hz]

ONOFF

1Hz

0.1Hz

doc.: IEEE 802.11-09/0161r1

Submission

Doc.:IEEE 802.11-09/0537r0

-120

-100

-80

-60

-40

-20

-25 -20 -15 -10 -5 0 5 10 15 20 25

Rec

eive

d P

ower

[dB

]

Frequency [Hz]

• In the channel model of IEEE802.11n, 0 Hz component was removed from the measured Doppler frequency not to include the direct path component. • However, we found that 0 Hz component still existed even in the LOS environment. fd was around 0.05~0.2 Hz so the Doppler frequency in a typical office may be lower than that in IEEE802.11n channel model.

Comparison between LOS and NLOS

NLOS

fd=0.05Hz

-120

-100

-80

-60

-40

-20

-25 -20 -15 -10 -5 0 5 10 15 20 25

Rec

eive

d P

ower

[dB

]

Frequency [Hz]

LOS

fd=0.05Hz

doc.: IEEE 802.11-09/0161r1

Submission

Doc.:IEEE 802.11-09/0537r0

CDF of Measured Doppler Frequency

0.01 0.1 10

20

40

60

80

100

Doppler frequency [Hz]

Cum

mul

ativ

e D

ensi

ty F

unct

ion

[%]

The measured Doppler frequency are around 0.1Hz and Doppler frequency variation is small in each measurement.

1st mes.2nd mes.3rd mes.4th mes

Interval of the measurement: 10 minutes

Time duration for each measurement: 30 seconds

doc.: IEEE 802.11-09/0161r1

Submission

Doc.:IEEE 802.11-09/0537r0

Conclusion

• Dependency on the fluorescent condition was not observed in our measurement. The estimated fd from the measured data was around 0.05~0.2Hz which was much lower than that of IEEE802.11n channel model.

• Ignoring 0 Hz component may not be a reasonable way to evaluate fd because high level of 0Hz component was observed even in NLOS environment.

• Doppler frequency variation is small in infoor office environment.