Measurement Procedures in Reverberation Chambers€¦ · Reverberation chambers are being used for...

1

MIMO and other Wireless Measurements in

Reverberation Chambers at NIST

Presented by: William Young

C. L. Holloway, K.A. Remley, J. Ladbury, G. Koepke, W.F. Young,

R. Pirkl, E. Genender, S. Floris, H. Fielitz

National Institute of Standards and Technology

Electromagnetics Division

Boulder, Colorado

303-497-3471, email: [email protected]

July 2011, SPOKANE, WA

Content

• Basics of Radio Frequency Reverberation

Chambers

• Key Reverberation Chambers Characteristics for

Wireless Measurements

• Creating Realistic Environments for Testing

Wireless Devices

• Reverberation Chamber Test Environments for

MIMO Systems

2

BASICS OF RADIO

FREQUENCY

REVERBERATION CHAMBERS

OPEN AREA TEST SITES (OATS)

Problems:Ambients

Reflections

Scanning

Interference

Positioning

3

ANECHOIC CHAMBER

Problems:Low Frequencies

Reflections

Positioning

Directional Antennas

REVERBERATION CHAMBER

Why use a reverberation chamber?

1) Relatively inexpensive

2) Relatively fast

3) Multipath environment- useful

for MIMO testing

4

Commercial Solutions…

• Stirrer

• Turntable

Reverberation chambers are being used for a

wide range of EM and EMC measurements.

Reverberation Chamber

D-U-TTransmit Antenna

Receive AntennaProbe(s)

Transmit Instrumentation:

Signal Generator

Amplifier

Directional coupler

Power Meter(s)

etc.

Motor Control

Control and Monitoring

Instrumentation for

Device-under-test

Receive Instrumentation:

Spectrum Analyzer

Receiver, Scopes

Probe System

etc.

5

Fields in a Metal Box (A Shielded Room)

•In a metal box, the fields have well defined modal field distributions.

Locations in the chamber with very high field values

Locations in the chamber with very low field values

Frozen Food

Fields in a Metal Box with Small Scatterer

(Paddle)

In a metal box, the fields have well defined modal field distributions.

Small changes in locations where very high field values occur

Small changes in locations where very low field values occur

6

Fields in a Metal Box with Large Scatterer (Paddle)

Large changes in locations where very high field values occur

Large changes in locations where very low field values occur

In fact, after one fan rotation, all locations in the chamber will have nearly the

same maxima and minima fields.

Stirring MethodTIME DOMAIN

Click to play paddle

rotation

750MHz

Paddle

7

Reverberation Chamber: All Shape and Sizes

Large Chamber

Small Chamber

Moving walls

Huge ChamberNASA: Glenn Research Center

Original Applications

• Radiated Immunity

components

large systems

• Radiated Emissions

• Shielding

cables

connectors

materials

• Antenna efficiency

• Calibrate rf probes

• RF/MW Spectrograph

absorption properties

• Material heating

• Biological effects

• Conductivity and

material properties

8

KEY REVERBERATION

CHAMBER

CHARACTERISTICS FOR

WIRELESS MEASUREMENTS

Wireless Applications

• Radiated power of mobile phones

• Antenna efficiency measurements

• Measurements of receiver sensitivity of mobile terminals

• Investigating biological effects of cell-phone base-station RF exposure

• Device testing in emulated Rayleigh multipath environments

• Device testing in emulated Rician multipath environments

• Gain obtained by using diversity antennas in fading environments

• Measurements on multiple-input multiple-output (MIMO) systems

9

Standardization of Wireless Measurements

Can we use a reverberation chamber as a reliable and

repeatable test facility that has the capability of simulating

key multipath environments for the testing of wireless

communications devices?

If so, such a test facility will be useful in wireless

measurement standards.

Testing Application: Total Radiated Power

from Cell-PhonesData from CTIA working group on total radiated power (TRP) testing:

TRP Comparison, Free Space, Slider Open, W-CDMA Band II

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

Low Mid High

Reference Channel

Re

lati

ve

TR

P

Anechoic Lab A Band II

Anechoic Lab B Band II

Anechoic Lab C Band II

Reverb Lab A Band II

Reverb Lab B Band II

Reverb Lab C Band II

Reverb Lab D Band II

Reverb Lab E Band II

TRP Comparison, Free Space, Slider Open GSM850

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

Low Mid High

Channel

Re

lati

ve

TR

P

Anechoic Lab A GSM850

Anechoic Lab B GSM850

Anechoic Lab C GSM850

Reverb Lab A GSM850

Reverb Lab B GSM850

Reverb Lab C GSM850

Reverb Lab D GSM850

Reverb Lab E GSM850

Reverb chamber

data has less

variability than

the anechoic data!

10

Can we model multipath environments in a

reverberation chamber?

Reverberation Chambers are

Natural Multipath Environments

11

Reverberation Chamber Provides a

Statistically Uniform Channel

21

1.5 GHz 2.5 GHz

• At a single frequency, observed received power is not uniformly distributed over azimuth.

Power vs. Azimuth Angle

Channel is Frequency Dependent

22

Power vs. Azimuth Angle: Paddle Configuration A

• Strong frequency dependence is indicative of an isotropic scattering environment.

• Constructive and destructive interference cause peaks and nulls.

12

Power vs. Azimuth Angle: 3.6 MHz BW

1.5 GHz 2.5 GHz

23

• Received power is distributed more uniformly when observed over some bandwidth.

Multipath Environments

Extensive measurements have shown that when light of sight (LOS) path is present

the radio multipath environment is well approximated by a Ricean channel, and

when no LOS is present the channel is well approximated by a Rayleigh channel:

The Amplitude of E is either Rayleigh or Ricean depending if a LOS path is present.

Urban Environment Rural Environment

13

Ricean K-factor

componentsscattered

componentdirectk or K = 10Log(k)

K=10 dBK=4 dB

K=1 dBK= -∞ dB

(Rayleigh)

K-factor:

Typical Reverberation Chamber Set-up

Antenna pointing away from probe (DUT)

Paddle

Transmitting Antenna

metallic walls

DUT

a

a

A Rayleigh test environment

Can we generate a Ricean environment?

14

Chamber Set-up for Ricean Environment

Antenna pointing toward (DUT)

We will show that by varying the characteristics of the reverberation

chamber and/or the antenna configurations in the chamber, any desired

Rician K-factor can be obtained.

Paddle

DUT

Transmitting Antenna

metallic walls

Reverberation Chamber Ricean Environment

Calculating the Ricean K-factor in a reverberation chamber [1]

• K is proportional to D. This suggests that if an antenna with a well defined antenna

pattern is used, it can be rotated with respect to the DUT, thereby changing the K-factor.

•If r is large, K is small (approaching a Rayleigh environment)

•If r is small, K is large. This suggests that if the separation distance between the antenna

and the DUT is varied, then the K-factor can also be changed to some desired value.

•By varying Q (the chamber quality factor), the K-factor can be changed.

• If K becomes small, the distribution approaches Rayleigh.

Thus, varying all these different quantities in a judicious manner can result in

controllable K-factor over a reasonably large range.

15

Measured K-factor for Chamber Loading

The thick black curve running over each data set represents the K-factor obtained

by using d determined in the anechoic chamber.

1.0E-02

1.0E-01

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1000 2000 3000 4000 5000 6000 7000

Frequency (MHz)

K-f

ac

tor

2 pcs absorber

6 pcs absorber

0 pcs absorber

Simulating Propagation Environments

with Different Impulse Responses and RMS Delay Spreads

0 1000 2000 3000

2

4

6

8

10x 10

-12

Delay (ns)

PD

P (

linear)

Rx8rms

= 105 ns

Ground Plane

Transmitting

antenna

tripods

62 inches

VNA

Port 1 Port 4

200 m

Optical

Fiber

Receiving

antenna

Fiber Optic

Receiver

OpticalRF

Fiber Optic

Transmitter

OpticalRF

0 1000 2000 3000

1

2

3

4

5

6

7

x 10-13

Delay (ns)

PD

P (

linear)

Rx12rms

= 232 ns

16

S21 Measurements: Loading the Chamber

Impulse Responses and Power Delay Profiles

Loading the Chamber

Power Delay Profile:

where h(t) is the Fourier transform of S21(w)

17

RMS Delay Spreads from Q measurements

where K is the K-factor and a threshold.

Thus, once we have Q, we can estimate rms

Impulse Responses and RMS Delay Spreads

for Different Ricean K-factors

18

Same Absorber, Different PDPs

0 500 1000 1500 2000-130

-120

-110

-100

-90

-80

-70

-60

Mean Power Delay Profile (100 steps)

Delay (ns)

Po

we

r D

ela

y P

rofil

e (

dB

)

Horn Indirect 1, Absorber A


Horn Indirect 1, Absorber B


Horn Indirect 1, Absorber C


Horn Direct CoPol, Absorber B

Horn Direct XPol, Absorber B

0 500 1000 1500 2000-130

-120

-110

-100

-90

-80

-70

-60

Mean Power Delay Profile (100 steps)

Delay (ns)

Po

we

r D

ela

y P

rofil

e (

dB

)







Omni Direct CoPol, Absorber B

Omni Direct XPol, Absorber B

•Different antenna types can impact PDP, just as absorber can

Horns Omnis

Instantaneous Results Can Vary

0 20 40 60 80 1000

20

40

60

80

100

120

140

160

180

200

Paddle Position

RM

S D

ela

y S

pre

ad

(n

s)

RMS Delay Spread at Each Paddle Position

3 Abs Floor, Horn Pos 1

3 Abs Floor, Horn Pos 2

1 Abs Floor, 2 Abs Raised, Horn Pos 1

1 Abs Floor, 2 Abs Raised, Horn Pos 2

3 Abs Raised, Horn Pos 1

3 Abs Raised, Horn Pos 2

0 100 200 300 400 500 600 700 8000

2

4

6

8

10

12

14

16

18

20

Delay (ns)

Po

we

r D

ela

y P

rofil

e (

line

ar

un

its)

All PDPs, Antenna Position 2a, Abs Ht 2, Xpol

19

BER Measurements – setup*Agilent 4438C Vector Signal Generator

Agilent 89600 Vector Signal Analyzer

External trigger

Firewire connection

to control VSA

GPIB connection

to control VSG

Reverberation chamber

*Mention of products by name does not imply endorsement

by NIST. Other products may work as well or better.

BER Measurements*Calibration: determine delay between received external trigger and the first demodulated bit of the

pattern

This offset depends on the signal bit rate.

Measurement: VSG repeatedly transmits an a priori known bit pattern

VSA locks on the external trigger and stores the received bit pattern

VSA integrates the signal spectrum to find the received signal power

LabVIEW: receives the bits from the VSA

corrects for the determined offset

calculates the BER

Each measurement is

finished when the BER

has settled

This measurement is repeated

for a range of VSG transmit powers

0 0.5 1 1.5 2 2.5 3 3.5

x 106

0

0.01

0.02

0.03

0.04

0.05

0.06

Number of received bits [N]

BE

R

BER running average - 24.3 ksps BPSK with slow paddle speeds

VSG transmit power: -65 dBm



*Mention of products by name does not imply endorsement by NIST. Other products may work as well or better.

20

BER Measurements

BER for a 243 ksps BPSK signal

BER for a 786 ksps BPSK signal

CREATING REALISTIC

ENVIRONMENTS FOR

TESTING WIRELESS DEVICES

21

Difficult Radio Environments

NIST is measuring signal penetration and multipath in representative emergency response

environments to provide data for improved wireless device design, standards development,

and better channel models.

Apartment Building

Oil RefineryOffice Corridor

Subterranean Tunnels

Small Chamber = Large Structure?

•Omnidirectional antennas

•Instantaneous differences (even if mean characteristics match)

•Monotonic, exponential decay

•Decay time

0 1000 2000 3000

2

4

6

8

10x 10

-12

Delay (ns)

PD

P (

linear)

Rx8rms

= 105 ns

0 1000 2000 3000

1

2

3

4

5

6

7

x 10-13

Delay (ns)

PD

P (

linear)

Rx12rms

= 232 ns

22

Example: Denver High-Rise Building Tests

North

South

East

West1

2

35

4

67

8109

11121314

1516

21

20

19

18

17

VNA measurement test locations are in pink

Ground Plane

Transmitting

antenna

tripods

62 inches

VNA

Port 1 Port 4

200 m

Optical

Fiber

Receiving

antenna

Fiber Optic

Receiver

OpticalRF

Fiber Optic

Transmitter

OpticalRF

Can we replicate the Denver high-rise in a

reverberation chamber?

absorber

wireless device

antenna

mode stirrers

horn antenna

Reverberation chamber with absorbing material

and phantom head0 50 100 150 200 250 300 350 400 450 500

time (ns)

-70

-65

-60

-55

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

Po

we

r D

ela

y P

rofile

(d

B)

1 absorber: rms=187 ns



Large office biulding

rms=59 ns

23

Can the reverberation chamber simulate an oil

refinery?Power Delay Profile in an oil refinery.

Lab-Based Test Method

North

South

East

West1

2

35

4

67

8109

11121314

1516

21

20

19

18

17

VNA measurement test locations are in pink

Location and

Notes

Test Point VNA Loss

Data (dB)

Path Loss

@700 MHz

(dB)

RMS Delay

Spread @700

MHz

(ns)

Republic

Notes:

- System 1

repeater at test

point 2.

1 7.23 68.6149 44.99

2 27.06 88.4449 39.52

3 38.15 99.5349 52.30

4 37.60 98.9849 133.41

5 37.18 98.5649 81.25

6 42.26 103.6449 102.78

7 46.04 107.4249 138.29

8 44.88 106.2649 104.69

9 48.30 109.6849 376.10

10 45.34 106.7249 338.17

11 50.25 111.6349 167.91

12 50.48 111.8649 231.57

13 50.98 112.3649 209.07

14 51.82 113.2049 192.25

15 49.60 110.9849 240.20

16 44.64 106.0249 377.45

17 29.28 90.6649 296.87

18 30.45 91.8349 161.75

19 42.24 103.6249 429.90

20 39.30 100.6849 333.25

21 47.07 108.4549 453.47

Compare wireless device performance measured in the field to performance in the

reverberation chamber

24

Adding More Realism to the PDP

T

T

R12

T1

T2

T3

R12

R9

R5

R10

•Mean of 27 NLOS

measurements made in Denver

urban canyon.

•Channel characterization and

PASS device measurements.

0 200 400 600 800 1000 1200

-170

-160

-150

-140

-130

-120

-110

-100

-90

Delay (ns)

PD

P (

dB

)

TX1 to RX5rms

= 115 ns

Noise Threshold = -116 dB

0 500 1000

-170

-160

-150

-140

-130

-120

-110

Delay (ns)P

DP

(dB

)

TX1 to RX9rms

= 39 ns

Noise Threshold = -116 dB

Clustering of Multipath is Common

0 100 200 300 400 500 600 700 800 900 10000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Delay [ns]

PD

P

fitted simulated data

measured Data Denver

RX

TX

Shortest path

Welton Street

17

th

Str

ee

t

Glenarm Pl

TX

RX

1

RX

2

RX

3

Transmitter Site

Parking lot

Mean of 27 NLOS

measurements

Clusters of

exponential

distributions off of

buildings

25

Channel Emulator (CE) and Vector Network

Analyzer (VNA) used with a Reverberation

Chamber

Generate a Complex Power Delay Profile [8]

26

REVERBERATION CHAMBER

TEST ENVIRONMENTS FOR

MIMO SYSTEMS

Motivation

Alternative transmit/receive

configurations can improve wireless

reception in weak-signal and multipath

environments

To verify performance of multiple

antenna algorithms, testing in a

multipath environment is desirable

We discuss methods for implementing

such test environments using

reverberation chambers

TX RX

TX RX

TX RX

TX RX

SISO

MISO

SIMO

MIMO

27

Measurement Set-up

VSG 1

VSA

LO in

LO out

I out

Q out

Event 1

RF out

VSG 2

LO in

LO out

I in

Q in

Event 1

RF out

Pattern sync.

LO in RF in

IEEE 1394

Firewire

GPIB

Reverberation chamber

Stirrer

GPIB

•Multiple TX simulated using 2

VSGs

•Vector signal analyzer provides

channel power and demodulated

data

•BPSK modulated signal;

random, equal distribution; 2048

bits

•Error correction only to recover

constellation after deep fade

•Paddle stepped

Test Methodology

INITInitialize the stirrer

Initialize the VSA

Beamforming?

Recording data

Stepping the stirrers

Switch antenna!Tells the user to switch to a

different antenna

Storing the data to file

Exiting the program

BeamformingShifting the phase until

maximum power is reached

at the receiver

Recording data

Switch antenna!Tells the user to switch to a

different antenna

Stepping the stirrers

All steps done?

All antennas

used?

All steps done?

All antennas

used?

Yes

No

No

Yes

Yes

No

Yes

No

No

Yes

•One receiver is used: repeatability and

post processing are key

•Careful synchronization of

generators, receiver, paddles required

•Post processing implements diversity,

MIMO schemes

•System is automated to prompt user

for correct inputs

•System applicable for design (laptop

antennas, for example) and test of

algorithms

28

NIST Chamber Characteristics

•Chamber dimensions:

4.28m x 3.66m x 2.90m

•Two paddles: vertical

and horizontal

•Table shows Q, RMS

delay spread, and

coherence bandwidth

for various numbers of

absorbing blocks

Absorber Q τ RMS [ns] Δf [MHz]0 47130 3121.99 0.321 8505 563.38 1.772 3319 220.08 4.543 2051 136.01 7.354 1479 98.06 10.205 1407 93.32 10.716 1067 70.66 14.147 918 60.82 16.428 765 50.71 19.729 731 48.48 20.62

10 550 36.49 27.4011 551 36.55 27.3612 435 28.83 34.6813 399 26.47 37.7714 369 24.48 40.8415 340 22.57 44.3016 332 22.03 45.38

•No choice of received signal •Antenna orientation sets level of

direct vs. reflected signal in the

reverb chamber

SISO

Real life Simulation in reverberation chamber

Transmitter Receiver

Vector

Signal

Generator

Vector

Signal

Analyzer

Reverberation

chamber

Stirrer

29

•Also called Diversity

•Power meter monitors

received signal strength

•Strongest signal

demodulated by receiver •VSA provides channel power

•Data from strongest signal

chosen in post processing

SIMO



Vector

Signal

Generator

Vector

Signal

Analyzer

Reverberation

chamber

StirrerA

B

Antenna A receives strongest

signal

Switch

B

A

Data A RX Power A

Data B RX Power B

RX Power A is strongest

In post processing Data A is selected

•TX antennas phase adjusted

to maximize received signal

•Received signal strength

relayed to transmitter

•Strongest signal demodulated

by receiver

•VSGs are phase locked

• Phase swept 360°

•Strongest channel power

chosen in post processing

TX BEAMFORMING



Vector

Signal

Analyzer

Reverberation

chamber

Stirrer

Phase

Signal strength

Vector Signal

Generator 2

Phase

Vector Signal

Generator 1

Signal strength

30

•Phasing of RX antennas

adjusted based on received

signal strength

•Strongest signal demodulated

by receiver

RX BEAMFORMING

Real life


Phase

Not implemented in the

simulation yet

Various schemes:•Precoding (like beamforming)

•Spatial multiplexing (data

broken into multiple streams, TX

on uncorrelated channels)

•Diversity coding (identical data

streams TX using orthogonal

codes. RX decides which one to

use)

•MISO => MIMO using post

processing

MIMO



Vector

Signal

Generator 1

Vector

Signal

Analyzer

Reverberation

chamber

Stirrer

Switch

B

A

Data A-C RX Power A-C

Data A-D RX Power A-D

Data B-C RX Power B-C

Data B-D RX Power B-D

Vector

Signal

Generator 2

C

D

31

Simulation of various MIMO

schemes:•Precoding: TX beamforming

used.

•Spatial multiplexing: TX data

start time not sufficiently precise

for simultaneous transmit. One

TX, one RX used in multiple

combinations. Data recombined in

post processing.

•Diversity coding: One RX so

only one code implemented. VSA

reports channel power, strongest

path chosen.

MIMO



Vector

Signal

Generator 1

Vector

Signal

Analyzer

Reverberation

chamber

Stirrer

Switch

B

A

Data A-C RX Power A-C

Data A-D RX Power A-D

Data B-C RX Power B-C

Data B-D RX Power B-D

Vector

Signal

Generator 2

C

D

Measured Results:

Various Data Rates

Frequency = 2.4 GHz

Pout = -50 dBm

BPSK modulated signal

•Best performance:

RX diversity with TX beamforming

and MIMO

•Huge increase in BER for high data

rates may be affected by coherence

BW of chamber

0

5

10

15

20

25

30

768 ksps

1 Msps 2.5 Msps

3 Msps5 Msps 10 Msps

BER

[%

] SISO

Receive diversity (MISO)

MIMO without beamforming

0

5

10

15

20

25

30

768 ksps

1 Msps

2.5 Msps

3 Msps

5 Msps

10 Msps

BER

[%

] TX beamforming (SIMO)

Receive diversity with TX beamforming

MIMO

32

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

1 2 3 4 5 6 7 8 9

10

11

12

BE

R [

%]

Number of absorbers inside chamber

BER SISO

BER MISO

BER SIMO

BER MIMO no Beamforming

BER MIMO

Number of Absorbers

Frequency = 2.4 GHz

Pout = -50 dBm

BPSK modulated signal, 768 ksps

70%

Non-line-of-sight: Nested Reverberation Chamber

Line of sight,

no nested chamberLine of sight, with

nested chamber

No line of sight,

with nested chamber

1. The paddle in the outer

chamber is turned through

100 positions, over 360⁰.

2. Paddle in the nested chamber

is turned continuously.

33

Nested Chamber Wireless Environment

0

50

100

150

200

250

300

0 10 20 30 40 50 60 70 80

RM

S D

elay S

pre

ad (

ns)

Threshold (dB)

LOS, w/o nested chamber

LOS, w/ nested chamber, w/ small paddle

NLOS, w/nested chamber, w/o small paddle

NLOS, w/ nested chamber, w/ small paddle

1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6-21

-18

-15

-12

-9

-6

-3

0

mean K values: -4.3 -5.3 -6.9 -10.7

Frequency, (GHz)

K-F

acto

r, (

dB)

LOS, w/o nested chamber

LOS w/ nested chamber, small paddle

NLOS w/ nested chamber, w/o small paddle

NLOS w/ nested chamber, w/ small paddle

Nested Chamber

Network

Analyzer

Large, outer

Chamber

MIMO Antenna

(Ports 1 & 2)

MIMO Antenna

(Ports 3 & 4)

Measuring MIMO Channel Correlation using a Nested

Reverberation Chamber

1 2 3 40

0.2

0.4

0.6

0.8

1

Chamber Configuration

|S

#,S

#|

S42,S24

S42,S41

S41,S31

S42,S32

S41,S32

S31,S32

Low correlation in

S-parameters =

good MIMO channel

Chamber Configurations (2.4 GHz):

1) No stirring in small chamber

2) Stirring in both; no RF absorbers

3) Stirring in both, one RF absorber

4) Stirring in both, two RF

absorbers

34

Correlation in the Nested Chamber MIMO Channels

(2.4 GHz)Without small paddle stirring

S13 S14 S23 S24 S31 S32 S41 S42

S13

S14

S23

S24

S31

S32

S41

S42

With small paddle stirring

S13 S14 S23 S24 S31 S32 S41 S42

S13

S14

S23

S24

S31

S32

S41

S42


and one absorber

S13 S14 S23 S24 S31 S32 S41 S42

S13

S14

S23

S24

S31

S32

S41

S42


and two absorbers

S13 S14 S23 S24 S31 S32 S41 S42

S13

S14

S23

S24

S31

S32

S41

S42

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Reverberation Chamber Standards Proposed

Testing MethodsStandards

•International Standard IEC 61000-4-21: Testing and

measurement techniques – Reverberation chamber test methods

•3rd Generation Partnership Project (3GPP) RAN4

– R4-111690, “TP for 37.976: LTE MIMO OTA Test Plan for

Reverberation Chamber Based Methodologies”

Testing Methods•CTIA Certification Program Working Group Contribution

– RCSG090101, P.-S. Kildal and C. Orlenius, “TRP and TIS/AFS

Measurements of Mobile Stations in Reverberation Chambers (RC)”

• “Utilizing a channel emulator with a reverberation chamber to

create the optimal MIMO OTA test methodology”

– C. Wright, S. Basuki, [8]

35

Challenges and Opportunities in Reverberation

Chamber Wireless Testing

• Direct path with omnidirectional antennas

• Tuning decay times = field non-uniformity

• How to test devices with repeaters

• Creating complicated PDPs for wireless device test

• Automating PDP development

• Advanced transmission, multiple antenna systems

• Test methods (CTIA, 3GPP groups)

• Angle of arrival measurements

• Uncertainties

Conclusions and Observations

1. Reverberation chambers represent reliable and repeatable test facilities that have

the capability of simulating any multipath environment for the

testing of wireless communications devices.

2. Such a test facility will be useful in the testing of the operation and

functionality of the new emerging wireless devices in the future.

3. Such a test facility will be useful in wireless measurements standards.

• Radiated power of mobile phones

• Receiver Sensitivity

• Gain obtained by using diversity antennas in fading environments

• Antenna efficiency measurements

• Measurements on multiple-input multiple-output (MIMO) systems

• Emulated channel testing in Rayleigh multipath environments

• Emulated channel testing in Rician multipath environments

• Measurements of receiver sensitivity of mobile terminals

• Investigating biological effects of cell-phone base-station RF exposure

36

References from NIST on Wireless Measurements

in Reverberation Chambers [1] C.L. Holloway, D.A. Hill, J.M. Ladbury, P. Wilson, G. Koepke, and J. Coder, “On the Use of Reverberation

Chambers to Simulate a Controllable Rician Radio Environment for the Testing of Wireless

Devices”, IEEE Transactions on Antennas and Propagation, Special Issue on Wireless

Communications, vol. 54, no. 11, pp. 3167-3177, Nov., 2006.

[2] E. Genender, C.L. Holloway, K.A. Remley, J.M. Ladbury, G. Koepke, and H, “Simulating the Multipath

Channel with a Reverberation Chamber: Application to Bit Error Rate Measurements,” IEEE

Transactions on EMC, vol. 52, no 4, pp. 766 – 777, Nov. 2010.

[3] E. Genender, C.L. Holloway, K.A. Remley, J. Ladbury, G. Koepke and H. Garbe, “Using Reverberation

Chamber to Simulate the Power Delay Profile of a Wireless Environment”, EMC Europe 2008,

Sept, 2008, Hamburg, Germany.

[4] H. Fielitz, K.A. Remley, C.L. Holloway, Q. Zhang, Q. Wu, and D. W. Matolak, “Reverberation-Chamber

Test Environment for Outdoor Urban Wireless Propagation Studies”, IEEE Antennas and Wireless

Propag. Lett., 2009.

[5] K.A. Remley, H. Fielitz, and C.L. Holloway, Q. Zhang, Q. Wu, and D. W. Matolak, “Simulation of a MIMO

system in a reverberation chamber”, IEEE EMC Symp. August 2011

[6] K.A. Remley, S.J. Floris, and C.L. Holloway, “Static and Dynamic Propagation-Channel Impairments in

Reverberation Chambers,” submitted to IEEE Transactions on EMC, 2010.

[7] D. Hill, “Electromagnetic Fields in Cavities: Deterministic and Statistical Theories” , IEEE Press, Copyright

© 2009.

Other References on Wireless Measurements

in Reverberation Chambers [8] C. Wright, S. Basuki, "Utilizing a channel emulator with a reverberation chamber to create the optimal

MIMO OTA test methodology," Mobile Congress (GMC), 2010 Global , vol., no., pp.1-5, 18-19

Oct. 2010.

[9] N. Serafimov, P.-S. Kildal, and T. Bolin, “Comparison between radiation efficiencies of phone antennas and

radiated power of mobile phones measured in anechoic chambers and reverberation chambers,”

in Proc. IEEE Antennas Propag. Int. Symp. 2002, Jun. 2002, vol. 2, pp.478–481.

[10] P.-S. Kildal, K. Rosengren, J. Byun, and J. Lee, “Definition of effective diversity gain and how to measure

it in a reverberation chamber,” Microwave Opt. Technol. Lett., vol. 34, no. 1, pp. 56–59, Jul. 2002.

[11] K. Rosengren and P.-S. Kildal, “Radiation efficiency, correlation, diversity gain, and capacity of a six

monopole antenna array for a MIMO system: Theory, simulation and measurement in reverberation

chamber,” Proc. Inst. Elect. Eng. Microwave, Antennas, Propag., vol. 152, no. 1, pp. 7–16, Feb.

2005.

[12] M. Lienard and P. Degauque, “Simulation of dual array multipath channels using mode-stirred

reverberation chambers,” Electron. Lett., vol. 40, no. 10, pp. 578–5790, May 2004.

[13] P.-S. Kildal and K. Rosengren, “Electromagnetic analysis of effective and apparent diversity gain of two

parallel dipoles,” IEEE Antennas Wireless Propag. Lett., vol. 2, pp. 9–13, 2003.

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