The CDMA is a broadband single frequency cellular system that maintains resource balance dynamically, mainly by power control. A repeater in the network may serve for enhancement of coverage or capacity. It interacts with the network paramters. Analysis is provided herein.

1. Repeaters in CDMA network
• Dr. Joseph Shapira
PROPRIETARY AND CONFIDENTIAL
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2. Parameters affecting capacity
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•
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•
•
•
•
•
•
•
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Power (FL) limit
Effect - Blocking
Measure - Power-per-user, blocking rate
Interference (RL) limit
Measure – noise rise ( may have an access limit set by the system)
Effect - Access failures, dropped calls, coverage reduction
(“breathing”)
Measure – (RL) access failures/ dropped calls rates
Excess SHO
Draws power from multiple cells – limits FL power
Increases overhead communications
Draws channel cards
PROPRIETARY AND CONFIDENTIAL
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3. Capacity Measurements
• Measure – Power per WC (Power per user).
•
This is an average measurement, that assumes the same
user distribution and data flow per user.
•
P/WC is sensitive to coverage, and has to be corrected
for change of coverage, if channel changes are measured
(diversity)
•
Pilot power allocation % affects TCH power and capacity
• Measure - Blocking rate
•
A valid measure only for full load (saturation)
•
Disrupted by anti-saturation means (e.g. AOC)
• Noise Rise – (may have a limit by the system)
PROPRIETARY AND CONFIDENTIAL
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4. CDMA optimization parameters
•Improve the channel –
reduce Eb/Nt required margin
– Receive diversity
– Transmit diversity
•Reduce link loss variations
– Distributed antennas
– Repeaters
•Reduce SHO overhead
– Increase the transmissionloss slope
– Balance FWD and RVS links
– Access Control
•Balance the loads
– Intersector
– Intercell
•Optimize the service
•Dynamic optimization is the next
frontier
PROPRIETARY AND CONFIDENTIAL
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5. Time Delay Transmit Diversity (TDTD)
Performance Comparison - Sector 21Z
4.9
4.4
3.9
P blocking [%]
3.4
Blocking
probability
w/o TDTD
w TDTD - Before Tilt
Residential area
2.9
2.4
2
%
1.9
1.4
increase in capacity 70%
( dB gain 2 . 3 )
0.9
Performance Comparison - Sector 21X
0.4
-0.1
5200
300
400
500
600
Minutes of Use
4.5
4
( dB gain 1
w TDTD
2.5
1
Highway traffic
w/o TDTD
[%]
P blocking
3
1.5
800
increase in capacity 25%
3.5
2
700
2
%
)
0.5
0
700
900
1100
1300
Minutes of Use
1500
1700
1900
PROPRIETARY AND CONFIDENTIAL
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6. Indoors Penetration enhancement
by a repeater across-the-street, with
Transmit Diversity plus TTLNA
2
3
1.8
2.5
1.6
1.4
2
1.2
1
1.5
0.8
1
0.6
0.4
0.5
0.2
0
-10
-5
0
5
10
15
20
25
0
-25
-20
-15
5dB
-10
-5
0
5
10
15
-4dB
RSSI {with TD – w/o TD } [dB] Distribution
Handset Tx Power {with TD – w/o TD} [dB] Distribution
PROPRIETARY AND CONFIDENTIAL
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7. Network Optimization/ Capacity
Maximization Process
•Improve the channel –
reduce Eb/Io required margin
– Receive diversity
– Transmit diversity
•Reduce link loss variations
– Distributed access
– Repeaters
•Reduce SHO overhead
– Increase the transmissionloss slope
– Balance FWD and RVS links
– Access Control
•Balance the loads
– Intersector
– Intercell
•Optimize the service
•Dynamic optimization is the next
frontier
PROPRIETARY AND CONFIDENTIAL
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8. Network Optimization/ Capacity
Maximization Process
•Improve the channel –
reduce Eb/Io required margin
– Receive diversity
– Transmit diversity
•Reduce link loss variations
– Distributed antennas
– Repeaters
•Reduce SHO overhead
– Antenna control
– Balance FWD and RVS links
– Access Control
•Balance the loads
– Intersector
– Intercell
•Optimize service
•Dynamic optimization is the next
frontier
PROPRIETARY AND CONFIDENTIAL
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9. Number of Sectors involved in a call
A Major Metropolitan Market, US
Site # X
Site # Y
2.3
1.5
2.1
3.4
2.2
PROPRIETARY AND CONFIDENTIAL
2.2
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10. Power Inefficiency factor
Site # X
Site # Y
20 - 30%
[Simple+2*CTrfCode+ChnSrHO+2.25*CTrfCode+ChnSHO] / [Simple+CTrfCode+ChnSrHO+CTrfCode+ChnSHO]
PROPRIETARY AND CONFIDENTIAL
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11. Network Optimization/ Capacity
Maximization Process
•Improve the channel –
reduce Eb/Io required margin
– Receive diversity
– Transmit diversity
•Reduce link loss variations
– Distributed antennas
– Repeaters
•Reduce SHO overhead
– Increase the transmissionloss slope
– Balance FWD and RVS links
– Access Control
•Balance the loads
– Intersector
– Intercell
•Optimize service
•Dynamic optimization is the next
frontier
PROPRIETARY AND CONFIDENTIAL
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12. Network Optimization/ Capacity
Maximization Process
•Improve the channel –
reduce Eb/Io required margin
– Receive diversity
– Transmit diversity
•Reduce link loss variations
– Distributed antennas
– Repeaters
•Reduce SHO overhead
– Increase the transmissionloss slope
– Balance FWD and RVS links
– Access Control
•Balance the loads
– Intersector
– Intercell
•Optimize service
•Dynamic optimization is the next
frontier
PROPRIETARY AND CONFIDENTIAL
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13. The Smart Cluster
Add-On Dynamic Optimization
Cluster size - 10 to 15 cells
Objectives
Sensors
Optimization
Communication
Mobile units
BTS RF state
Repeaters
Antenna state
Switch – performance parameters
Effectors
Communication
RET and RBC Antennas
Repeater gain
BTS pilot level
Neighbor list
Search window
Additional parameters
PROPRIETARY AND CONFIDENTIAL
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14. Repeater usage for Maximizing
Capacity
1.
2.
3.
4.
5.
6.
Hot spots
Indoor illumination from outdoor
Indoor distribution (DAS)
Increase transmission slope/ reduce SHO
Load balancing
Add diversity
γ
β
α
PROPRIETARY AND CONFIDENTIAL
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15. Types of Repeaters
1.
2.
3.
4.
Embedded
Border extension
Remote
Cascaded
D3
D1
1
RR3
RC
D2
3
RR1
2
PROPRIETARY AND CONFIDENTIAL
RR2
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16. Forward Link
•Relays all donor transmission ( plus other interfering
sources)
y F = TDF GRF
•No automatic balancing RVS/FWD
•Has to be controlled for coverage (gain) and saturation
(AMLC)
•Reduces RSU (repeater-served-users) per-user power
•Increases PiCH/TCH ratio for RSU (TCH is power-controlled)
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PROPRIETARY AND CONFIDENTIAL

17. Impact of Repeaters on the Network - FL
•
Net gain (yF) determines coverage
•
•
•
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Excess gain causes oscillations/spurii
AMLC reduces coverage, causes imbalance and reduces capacity
Amplifying other sources may lead to AMLC
Instability of the BS-Repeater (BSR) link (e.g. directive antenna nodding,
fiber loss change with temperature, etc.) changes coverage
Overlap with donor’s coverage adds multiple fingers to the MS receiver,
introduces interference (excess fingers) and diversity
Repeater delay requires broadening of the search window (significant in
fiber and selective repeaters)
•
•
PROPRIETARY AND CONFIDENTIAL
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18. Impact of repeater on network - RL
•Effective cell noise factor
FCE = FC + yFR
•Repeater adds RL noise
•Reduces donors’ coverage,
• or donor’s capacity.
•Trade-off repeater coverage
• vs. donor coverage/ capacity
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PROPRIETARY AND CONFIDENTIAL
n
Tc
Tr
TD
GB
GRR
FCE = FC + yFR
Repeater
FB
BTS
RC0
RC
RR
FR
m

19. RL Impact of repeater on network – cont.
• No Rx diversity – increases MTX and BTS load, and reduces
coverage
• Loads the donor noise and reduces its coverage and/ or
capacity
• Overlap introduces diversity. Excess fingers introduce
interference
• Change in BSR link gain causes change in coverage for both
repeater and donor
• Imbalance FL-RL (excess offset) causes the P.C. open loop to
be noisy, and loss of capacity. Imbalance exceeding about
close loop range breaks the P.C. loop and drops RSUs
PROPRIETARY AND CONFIDENTIAL
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20. Fixed Coverage vs. Fixed Capacity
• A
• B
•
Excess noise rise for fixed capacity (loss of coverage)
Loss of capacity for fixed noise rise
A
B
PROPRIETARY AND CONFIDENTIAL
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21. Coverage of repeaters
• Embedded
Border
Remote
Cell border
PROPRIETARY AND CONFIDENTIAL
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22. Repeater Controls
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Gain, RL
Power, RL
Gain, FL
Power, FL
AMLC – Automatic Level Control
Frequency filtering
Switching (advanced option)
BS-Repeater Link Gain
Antenna controls
PROPRIETARY AND CONFIDENTIAL
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23. Basic Repeaters
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Definition: Fixed frequency band/selective, fixed gain independent in
FWD/RVS, has maximum power protection (e.g. AMLC), provides alarms
and monitoring, no AISG provisioning (maybe external), no diversities,
simple RF F1-F1 (no dedicated conduit), no watermarking, no multi-hop,
includes a wireless modem
Parameters: FWD Gain, RVS Gain, RVS Tx Power, FWD Power, AMLC Level
and Status, Wireless Modem parameters forwarding (Ec/Io, RSSI, FER, Tx
PWR)
Optimization: Setting procedures (FWD, RVS, Noise Rise, Pilot PWR %,
balancing), search window, neighbor list
Parameters such as # carriers, traffic load, carriers' loading, BTS allowed
shrinkage, enter into setting and optimization as constraints
Incorporate repeaters in the optimization tool with shared BTS-Repeater
coverage, combined traffic, macro-diversity and interference, all above
setting considerations.
PROPRIETARY AND CONFIDENTIAL
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24. Advanced Repeaters
1.
2.
3.
4.
Repeater performance
Enhanced performance
Enhanced features
Network Parameters Readout
PROPRIETARY AND CONFIDENTIAL
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25. Advanced Repeaters
Repeater performance
1.
2.
3.
4.
5.
6.
Stability
Robustness
Installation – parameter setting
Alarm functions
Link balancing
Traffic, coverage, overhead
PROPRIETARY AND CONFIDENTIAL
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26. Enhanced performance
•
Interference cancellation
1. Adaptive angular interference cancellation
(adaptive donor antenna)
Filter-out other donors or interfering sources
2. Adaptive feedback cancellation
Reduces coupling between donor and service
antennas, allowing for tighter installation on the
tower
PROPRIETARY AND CONFIDENTIAL
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27. Enhanced features
1. Frequency filters
Inter-systems and sub-bands
1. Antenna control (RET/ RBC)
Control of repeater service antenna
1. Diversity FWD/RVS
True or pseudo-diversity (PSD/TDD)
1. Multi-carrier/ multi function
Multi-systems with separate controls
1. BTS-Repeater (backhaul) link stabilization
PROPRIETARY AND CONFIDENTIAL
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28. Network Parameters Readout
1. Traffic load through repeater
Limited effectiveness. The noise rise is affected by the
total donor+repeater load
1. Tagging repeater – “Water-marking” RSUs
Frequency or delay modulation of repeater RL. Requires
detection by BTS
1. Wireless Modem parameters’ monitoring
2. Switch parameters pre-filtering and processing
PROPRIETARY AND CONFIDENTIAL
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29. Cascaded (multi-hop) repeaters
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1.
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2.
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3.
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Repeaters are cascaded to increase coverage
Along roads
maximal area/ length
Within an area/ campus
mixed large/ small areas
Within buildings
limited area, complex coverage
Distribution (backhaul):
Star
Cascade
PROPRIETARY AND CONFIDENTIAL
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30. Star/ Cascade
• Star
•
•
Each repeater may be controlled independently
The aggregate apparent noise factor counts. Optimal
setting – same net gain to each.
• Cascade
•
RC
R1
R2
R3
R4
The gain setting of each repeater influence the rest of
the chain. The coverage is successively smaller. Optimal
setting – same net gain (y) to all repeaters but the first
(preferably y=1). Control the chain by the net gain of the first.
Total range
PROPRIETARY AND CONFIDENTIAL
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31. Setting
• Roads/ area
•
Maximizes for y=1. Repeaters and donor are planned and
optimized together.
• Indoors
•
Low net gain (y <<1). Small coverage. Minor impact on
donor coverage. Loosely interdependent optimization of
donor and repeater chain.
PROPRIETARY AND CONFIDENTIAL
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32. Network planning with repeaters
• Optimizing the repeaters’ location and their parameters’
setting is crucial for any further control and optimization of
the network.
• Major parameters:
•
Repeater RL/FL power, gain, dynamic range (per location
and purpose)
•
Repeater location
•
height, beam-width, direction and tilt of dservice
antenna
•
Backhaul link
PROPRIETARY AND CONFIDENTIAL
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33. Optimization with Repeaters
• Change repeater coverage vs. donor coverage
– Hot spot – Repeater coverage should exceed high density area
– Border – affects pilot pollution/ SHO extent
– Remote – rural coverage vs. core coverage
• Change repeater antenna orientation/ tilt
– Hot spot – controls overlap with donor (capacity, performance)
– Border – controls pilot pollution/ SHO extent
– Remote – controls Repeater coverage area
• Frequency Filters and service antenna control
– Controls load distribution/ service destination
• Switch
– Switch off dormant coverage and reduce noise
PROPRIETARY AND CONFIDENTIAL
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34. Enhancement Tools
CDMA wireless modem in the repeater
1. Reports repeater status
2. Relays commands to the repeater
3. Automatic FL/RL links balancing
By reading the offset parameter of the modem P.C. and
controlling repeater gains
1. Location
•
(e.g. by differentiating time-of-flight to modem
and to
subscriber)
5. Identifies PNs through repeater
Support reduction of interference from other sources
PROPRIETARY AND CONFIDENTIAL
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35. Thank you
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Contact
Dr. Joseph Shapira
Comm&Sens Ltd
+972 4 8251653
+972 54 6607088
Jshapira@comm-andsens.com
PROPRIETARY AND CONFIDENTIAL
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