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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
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Introduction
System Model
Performance Metrics
Single Cell Environment
Multicell Environment
Conclusion
ational Mobile Communications Research Laboratory, Southeast
University 2 / 31
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Introduction
System Model
Performance Metrics
Single Cell Environment
Multicell Environment
Conclusion
ational Mobile Communications Research Laboratory, Southeast
University 3 / 31
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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 thanin 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
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CRL@SEU 2010920 5
Conceptual description:
Limitations of conventional cellular architecture
The cell-edge problem
Very low spectral efficiency and power efficiency at cell
boundary !!!
r
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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
CooperationCoMP or DASnetwork MIMO
But the cell edge performance, by itself, was not well-
studied in the
literatureMotivationMotivationMotivationMotivation
ational Mobile Communications Research Laboratory, Southeast
University 6 / 31
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Introduction
System Model
Performance Metrics
Single Cell Environment
Multicell Environment
Conclusion
ational Mobile Communications Research Laboratory, Southeast
University 7 / 31
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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
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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
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Focus on the uplink
In each cell, the base station is assumed to be
loaded with one user
TDMAFDMA
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
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Introduction
System Model
Performance Metrics
Single Cell Environment
Multicell Environment
Conclusion
ational Mobile Communications Research Laboratory, Southeast
University 11 / 31
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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 otherrandom variables
ational Mobile Communications Research Laboratory, Southeast
University 12 / 31
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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
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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
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Metric 3 : the outage area
(km)
Capacity >
Capacity =
Capacity
