a compact tri-polarization antenna for mimo communication
TRANSCRIPT
UEC Tokyo
A Compact Tri-Polarization Antenna for MIMO Communication Systems
Yoshio KARASAWA & M. SHINOZAWA
Advanced Wireless Communication research Center (AWCC)
Univ. Electro-Communications (UEC Tokyo)
EMTS2007, OttawaJuly 27-28, 2007
UEC Tokyo
Contents of Presentation
1. MIMO Channel and its Capacity
2. Tri-Polarization Antenna
3. Hand-Made Radio Echoic Chamber
(Creation of Multipath-rich Environment)
4. Performance Characteristics
5. Conclusions
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MIMO Technologies
Tx signal Rx signal
Radiowave propagation
Tx arrayEncoding with time and space domain
Rx arrayDecoding with time and space domain
Multi-path propagation
Information theory and coding theory
Adaptive array and adaptive signalprocessing
MIMOcovers wide technical areas
Applications are from W-LAN to next-generation mobile wireless systems.
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Tx Rx
TX array
Eigen path #1
#2
#3
#4
RX array
Path profile (indoor)
MIMO Propagation Channel Model
Equivalent circuit modelbased on SVD
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Average Channel Capacity in iid Rayleigh Fading Environment
λλλγ dpN
mC unord
t
)(1log 0
201 ⎟⎟⎠
⎞⎜⎜⎝
⎛+= ∫
∞
⎟⎟⎠
⎞⎜⎜⎝
⎛+≈ λγ
tNm 0
2 1log
⎟⎠⎞
⎜⎝⎛ +=
mNm r0
2 1log γ
0CNr≈
( ) };1;1log{ 0020 rt NNC =>>+≡ γγ
Channel capacity is approximately proportional to the number of antennas when
(since <λ> = NtNr/m)
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Increase of Channel Capacity
Use of Dual-Polarization BranchesUse of Triple-Polarization Branches
Compact MIMO Antenna
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(H)(V)
HV
HV
Dual-Polarization antenna
Z
Z
(Z)
Triple-Polarization antenna
The tri-polarization antenna acts as a three-element MIMO antenna in the case of multipath-rich environment
N.K. Das et al., IEEE VTC2004 Fall, LA, Sep. 27-29, 2004.
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Creation of a Multipath-Rich Environment
Radio Echoic Chamber (Reverberation Chamber)as a Reference Environment
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Handmade Radio Echoic Chamber(Reverberation Chamber)
4m
2m
2m
Hutch
The chamber is enclosed with 20 aluminum plates (1mx2m plate)
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Radio-Echoic Chamber
Creation of an ideal multipath-rich environment
2m 4m
2m
The chamber is enclosed with 20 aluminum plates (1mx2m plate)
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-60 -50 -40 -30 -2010
-3
10-2
10-1
100
Received power (dB)
Cum
ulat
ive
prob
abili
ty
0 1 2 3 4-60
-55
-50
-45
-40
-35
-30
-25
-20
Delay (ms)
Pow
er (
dB)
5000 5020 5040 5060 5080 5100-60
-55
-50
-45
-40
-35
-30
-25
-20
Frequency (MHz)
Rec
eive
d po
wer
(dB
)
Tx pol . – Rx pol.V-V
στ = 430ns
Rayleighdist.
Measured Characteristics of Radio-Echoic Chamber
The characteristics are well represented by an outdoor multipath-rich environment!!
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-50 -45 -40 -35 -30 -25 -20
0
0.2
0.4
0.6
0.8
1
Received power when Tx power is 0dB [dB]
Cum
ulat
ive
prob
abili
ty
Radio Echoic Chamber(Multipath-rich environment)
ZV
Rx pol: Horizontal (H)
H H H
Z H
V H
CDF of Received Power for H-H, V-H, and Z-H
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-20 -15 -10 -5 0 5 100
0.2
0.4
0.6
0.8
1
Eigen value: λ1 [dB]
Cum
ulat
ive
prob
abili
ty
1 x 1(V-V)
2 x 2(V, H - V, H)
3 x 3(V, H, Z - V, H, Z)
The largest eigenvalue for multiple polarizations
(measured in a radio echoic chamber)
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1 10
0
0.2
0.4
0.6
0.8
1
Channel capacity [bit/s/Hz]
Cum
ulat
ive
prob
abili
ty
SNR=10dB
SNR=20dB
A B C D
A B C D
CDF of Channel Capacity
A: single pol. (1x1)
B: dual-pol. (2x2)
C: tri-pol. (3x3)
D: 3-antenna array(3x3)
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0
5
10
15
20
SNR = 10dBSNR = 20dB
Cha
nnel
cap
acity
(b/
s/H
z)
Case: A B C D
Average channel capacity when using multiple polarizations
A: single-pol. (V-V: 1x1)
B: dual-pol (V,H-V,H: 2x2)
C: tri-pol (V,H,Z-V,H,Z: 3x3)
D: three single-pol. antennas
by three single-pol. antennas
(V,V,V-V,V,V: 3x3)
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Conclusions
-Tri-polarization antenna, which is one of very compact antennas, showed a nearly the same performance of 3x3 single-pol MIMO array in multipath-rich environment.
We will evaluate the performance of the antenna in actual environments (both indoors and outdoors).