cell edge performance of cellular mobile · pdf file · 2011-06-27cell edge...
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Prof. Xiaohu You
National Mobile Comm. Research Lab., Southeast University
Shanghai Wireless Comm. Research Center
Cell Edge Performance of
Cellular Mobile Systems
� Introduction
� System Model
� Performance Metrics
� Single Cell Environment
� Multicell Environment
� Conclusion
�ational Mobile Communications Research Laboratory, Southeast University 2 / 31
� Introduction
� System Model
� Performance Metrics
� Single Cell Environment
� Multicell Environment
� Conclusion
�ational Mobile Communications Research Laboratory, Southeast University 3 / 31
� Future mobile communication systems should
provide high data rates and mass wireless access
services over a limited spectrum bandwidth
� Dramatic growth of wireless services: data, multimedia, broadband wireless Internet
� Radio spectrum becomes much more crowded than in the past
� Advanced transmission techniques improve the
spectrum efficiency
� Multiantenna techniques: Diversity, SDMA
� Multicarrier techniques: OFDM, GMC
�ational Mobile Communications Research Laboratory, Southeast University 4 / 31
东南大学移动通信国家重点实验室东南大学移动通信国家重点实验室东南大学移动通信国家重点实验室东南大学移动通信国家重点实验室（（（（�CRL@SEU）））） 2010年年年年9月月月月20日日日日 第第第第5页页页页
Conceptual description:
― Limitations of conventional cellular architecture
― The cell-edge problem
Very low spectral efficiency and power efficiency at cell boundary !!!
r
� Spectrum efficiency near the cell edge is still poor
� Cell edge users suffer from large path loss� Inter-cell interference
� The cell edge problem received much interests from
both academic and industry researchers. Some
countermeasures are proposed
� Interference management� Cooperation：CoMP or DAS、network MIMO
� But the cell edge performance, by itself, was not well-
studied in the literatureMotivationMotivationMotivationMotivation
�ational Mobile Communications Research Laboratory, Southeast University 6 / 31
� Introduction
� System Model
� Performance Metrics
� Single Cell Environment
� Multicell Environment
� Conclusion
�ational Mobile Communications Research Laboratory, Southeast University 7 / 31
Cellular configuration --- Collocated Antenna System
Cell-6
Cell-5
Cell-1
Cell-7
Cell-4
Cell-2
Cell-3
0--3 2 3-2
0
-
-3
2
3
-2
(0, 0)
1 1( , )� �
�ational Mobile Communications Research Laboratory, Southeast University 8 / 31
Cell-6
Cell-5
Cell-1
Cell-7
Cell-4
Cell-2
Cell-3
0--3 2 3-2
0
-
-3
2
3
-2
( , )n n� �
1 1( , )� �
(km
)
Cellular configuration --- Distributed Antenna System
�ational Mobile Communications Research Laboratory, Southeast University 9 / 31
� Focus on the uplink
� In each cell, the base station is assumed to be
loaded with one user
� TDMA、FDMA
� The composite channel fading model
� Path loss : depends on the distance between the user and the antennas of BSs
� Large scale fading (shadowing) : log-normal distributed
� Small scale fading : Rayleigh, Rice
�ational Mobile Communications Research Laboratory, Southeast University 10 / 31
� Introduction
� System Model
� Performance Metrics
� Single Cell Environment
� Multicell Environment
� Conclusion
�ational Mobile Communications Research Laboratory, Southeast University 11 / 31
� Location-specific capacity
� The concept of “cell edge” is based on the location
� For a given channel matrix H
( , )n n� �
1 1( , )� �
(km
)
BPU
� Conditioned on the locations of the user and the RAU, take expectation over other random variables
�ational Mobile Communications Research Laboratory, Southeast University 12 / 31
BPU
� Metric 1 : The average capacity in the inscribed
circle of the hexagonal cell edge
(√3/ 2) (km)
(km
)
BPU
�ational Mobile Communications Research Laboratory, Southeast University 13 / 31
� Metric 2 : the worst case location-specific capacity in
the cell
Collocated antenna system Distributed antenna system
BPU
�ational Mobile Communications Research Laboratory, Southeast University 14 / 31
� Metric 3 : the outage area
(km)
Capacity >
Capacity =
Capacity <
�ational Mobile Communications Research Laboratory, Southeast University 15 / 31
� Introduction
� System Model
� Performance Metrics
� Single Cell Environment
� Multicell Environment
� Conclusion
�ational Mobile Communications Research Laboratory, Southeast University 16 / 31
� Large frequency reuse factor is used
� Inter-cell interference is negligible
� Large path loss causes performance degradation in the cell edge
Result : Location-specific capacity in single cell environment
�ational Mobile Communications Research Laboratory, Southeast University 17 / 31
Location-specific capacity with the cell
-D -D/2 0 D/2 D -D -D/2 0 D/2 D-D
-D/2
0
D/2
D
0
10
20
30Location-specific capacity in the single cell environment (normalized SNR 0 dB)
Lo
ca
tio
n-s
pe
cific
ca
pa
city
(2,10,1) CAS(2,2,5) DAS
�ational Mobile Communications Research Laboratory, Southeast University 18 / 31
The average capacity over the inscribed circle (Metric-1)
-10 -8 -6 -4 -2 0 2 4 6 8 102
4
6
8
10
12
14
16
18
20
Normalized SNR c*P/Dα (dB)
bits/tra
nsm
issio
n
The average capacity in the circle of radius 0.866D
DAS (2,2,5)
CAS (2,10,1)
�ational Mobile Communications Research Laboratory, Southeast University 19 / 31
The worst-case location-specific capacity (Metric-2)
-10 -8 -6 -4 -2 0 2 4 6 8 100
2
4
6
8
10
12
14
16The worst-case location-specific capacity in the single cell environment
Normalized SNR c*P/Dα (dB)
bits/tra
nsm
issio
n
DAS (2,2,5)
CAS (2,10,1)
�ational Mobile Communications Research Laboratory, Southeast University 20 / 31
The contour map of the location-specific capacity
10
10
10
10
12
12
12
12
12
12
12
12
15
15
15
15
15
15
15
15
15
15
18
18
18
1818
18
18
18
18
18
21
21 21
21
21
21
21
21
21
21
30
30
30
30
30
Location (x-axis)
Location (
y-a
xis
)
DAS (2,2,5), normalized SNR 0 dB
-D -D/2 0 D/2 D-D
-D/2
0
D/2
DCAS (2,10,1), normalized SNR 0 dB
6.7
6.7
6.7
6.7
6.7
6.7
9
9
9
99
12
12
12
12
15
15
15
18
18
21
21 30
Location (x-axis)
Location (
y-a
xis
)
-D -D/2 0 D/2 D-D
-D/2
0
D/2
D
�ational Mobile Communications Research Laboratory, Southeast University 21 / 31
The outage area normalize by the area of the cell (Metric-3)
5 10 15 20 250
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Desired rate R
Th
e o
uta
ge
are
a n
orm
alize
d b
y th
e a
rea
of C
ell-1
Single cell environment
CAS, c*P/Dα = 0 dB
CAS, c*P/Dα = 5 dB
DAS, c*P/Dα = 0 dB
DAS, c*P/Dα = 5 dB
�ational Mobile Communications Research Laboratory, Southeast University 22 / 31
� Introduction
� System Model
� Performance Metrics
� Single Cell Environment
� Multicell Environment
� Conclusion
�ational Mobile Communications Research Laboratory, Southeast University 23 / 31
� The same radio spectrum is reused in all cells
� Severe inter-cell interference
� Large path loss
Result : Location-specific capacity in multicell environment
�ational Mobile Communications Research Laboratory, Southeast University 24 / 31
-D -D/2 0 D/2 D -D -D/2 0 D/2 D-D
-D/2
0
D/2
D
0
10
20
30Location-specific capacity in the multicell environment (normalized SNR 0 dB)
Lo
ca
tio
n-s
pe
cific
ca
pa
city
(2,10,1) CAS(2,2,5) DAS
Location-specific capacity with the cell
�ational Mobile Communications Research Laboratory, Southeast University 25 / 31
The average capacity over the inscribed circle (Metric-1)
-10 -8 -6 -4 -2 0 2 4 6 8 102
3
4
5
6
7
8
9
10
11
12The average capacity in the circle of radius 0.866D
Normalized SNR c*P/Dα (dB)
bits/tra
nsm
issio
n
DAS (2,2,5)
CAS (2,10,1)
�ational Mobile Communications Research Laboratory, Southeast University 26 / 31
The worst-case location-specific capacity (Metric-2)
-10 -8 -6 -4 -2 0 2 4 6 8 101
2
3
4
5
6
7
8
9The worst-case location-specific capacity in the multicell environment
Normalized SNR c*P/Dα (dB)
bits/tra
nsm
issio
n
DAS (2,2,5)
CAS (2,10,1)
�ational Mobile Communications Research Laboratory, Southeast University 27 / 31
The contour map of the location-specific capacity
Location (x-axis)
Location (
y-a
xis
)
DAS (2,2,5), normalized SNR 0 dB
7
7
77
9
9
9
9
9
9
9
9
12
12
12
12
12
12
12
12
12
12
16
16
16
16
16
16
16
16
16
16
21
21
21
21
21
3030
30
30
30
-D -D/2 0 D/2 D-D
-D/2
0
D/2
D
-D -D/2 0 D/2 D-D
-D/2
0
D/2
DCAS (2,10,1), normalized SNR 0 dB
4. 5
4.5
4.5
4.5
4.5
4.5
6.5
6.5
6.5
6.5
6.5
9
9
9
9
12
12
12
16
16 2
130
Location (x-axis)
Location (
y-a
xis
)
�ational Mobile Communications Research Laboratory, Southeast University 28 / 31
The outage area normalize by the area of the cell (Matric-3)
4 8 12 16 20 240
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Multicell environment
Desired rate R
Th
e o
uta
ge
are
a n
orm
alize
d b
y th
e a
rea
of C
ell-1
CAS, c*P/Dα = 0 dB
CAS, c*P/Dα = 5 dB
DAS, c*P/Dα = 5 dB
DAS, c*P/Dα = 5 dB
�ational Mobile Communications Research Laboratory, Southeast University 29 / 31
� Introduction
� System Model
� Performance Metrics
� Single Cell Environment
� Multicell Environment
� Conclusions
�ational Mobile Communications Research Laboratory, Southeast University 30 / 31
� Cell edge effect of cellular systems was evaluated;
� An analytical framework was presented
� Collocated antenna system, Distributed antenna system;� Single cell environment, Multicell environment;
� Three metrics were proposed to quantify the cell
edge performance
� Analysis results were provided for typical system configurations;
� The theoretical results will serve as a baseline for
future work on cell edge problem and its
countermeasures.
�ational Mobile Communications Research Laboratory, Southeast University 31 / 31
THANKS
�ational Mobile Communications Research Laboratory, Southeast University 32 / 31
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