how to minimize the impact of cell breathing
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How to Minimize the Impact of Cell Breathingon UMTS Networks
How to Minimize the Impact of Cell Breathingon UMTS Networks
Yannick DUPUCHAlcatel - Mobile Networks Division
GSM/UMTS Project Manager
Yannick DUPUCHAlcatel - Mobile Networks Division
GSM/UMTS Project Manager
IEEE Workshop on Applications and Services in
Wireless Networks 2002
July 3rd - 5th, 2002
IEEE Workshop on Applications and Services in
Wireless Networks 2002July 3rd - 5th, 2002
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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 2 All rights reserved 2002, Alcatel
AgendaAgenda
tFacing the Multimedia traffic increase
w Cell breathing and cell range evolution
w Strategic Cell Radius
tUpgrade your Network
w Advanced Radio Features
w Elaborating the deployment strategy
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tVarious data rates(from Voice 12.2kbps up to 384Kbps)
tVarious QoSand GoS(blocking, delay, throughput, BLER)
tVarious connection types(Real Time and Non Real Time)
tVarious traffic asymmetryand activitybehaviour.
Node BAir interface
Voice (CS/2%)File transfer (PS/5s)
Web browsing (PS/3s)
Video conference (CS/2%)
Shopping on line (PS/1s)
Interactive games (CS/1%)
3G UE
Cell Breathing
Multiservice Traffic characteristic
Cell Breathing
Multiservice Traffic characteristic
Multiservice
MultiserviceMultiservice
Different Data rates
Different Data ratesDifferent Data rates
Different Sensitivities
Different SensitivitiesDifferent Sensitivities
Different Footprints
Different FootprintsDifferent Footprints
Voice and Low DataRate (eg up to 64kb/s)Medium Data Rate
(eg 144kb/s)
High Data Rate
(eg 384kb/s)
tDifferent footprintsfor different servicestDifferent footprintsfor different services
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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 4 All rights reserved 2002, Alcatel
Service Coverage:
wBlue: Voice Only
w Green: Voice and CS64
w Red: Voice, CS 64 and PS384
Cell Breathing
Multiservice Environment
Cell Breathing
Multiservice Environment
1000 subs/km2 - Year 5
300 subs/km2 - Year 3
100 subs/km2 - Year 1Seamless Coverage
Coverage for each
service is trafficdependent
Cell shrinkage
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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 5 All rights reserved 2002, Alcatel
From traffic forecast to coverage prediction
Iterative Link Budget Dimensioning
From traffic forecast to coverage prediction
Iterative Link Budget Dimensioning
W-CDMARadio Parameters
UL & DL Cell rangeUL & DL Cell range
InterferenceInterference
TRAFFIC ANALYSISTRAFFIC ANALYSIS LINK BUDGET ANALYSISLINK BUDGET ANALYSISFinal
UL & DLCell
Range
FinalFinalUL & DLUL & DL
CellCellRangeRange
CellRange
assumption
Cel
lRange
Cel
lRange
assumption
assumption
Multiservice Trafficinputs
ULanalysis
DLanalysis
ULtraffic
DLtraffic
Iterative processuntil convergence
> Use of Multiservice traffic modelling and iterative interference calculation
in both uplink and downlink to get the evolution of the cell range
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Strategic cell radius
Fixing a time variant parameter
Strategic cell radius
Fixing a time variant parameter
> Strategic cell
range will define
the deployed
inter-site
distanceper
environment
Dense Urban / Cell range = f(Phases)
0.55
0.6
0.65
PHO PH1 PH2 PH3
Phases
Cellrang
e(km)
Voice with 1 carrier
Traffic increases
Example of
strategic cell radius
Site
Site
Site
Site
Site
Site
Site
Seamless coverage
Holes in
coverage1.5xR
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Advanced Features
Avoiding Cell Breathing problems by timely upgrade
Advanced Features
Avoiding Cell Breathing problems by timely upgrade
>Anticipate holes through coverage prediction
>Avoid holes by timely upgrade
t In case of Downlink limitation
w TX Diversity
w High power amplifier
t In case of Downlinklimitation
w TX Diversity
w High power amplifier
t In case of Uplink limitation
w Tower Mounted Amplifier (TMA)
w 4 Way RX Diversity
w Multi User Detection, MUD
t In case of Uplinklimitation
w Tower Mounted Amplifier (TMA)
w 4 Way RX Diversity
w Multi User Detection, MUD
tFor either Uplink or Downlink
limitation:
w Adding carriers
w Sectorisation
w Adding sites (densification)
w Smart antennas
tFor either Uplink or Downlink
limitation:
w Adding carriers
w Sectorisation
w Adding sites (densification)
w Smart antennas
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Tower Mounted Amplifier
Uplink Coverage Gain
Tower Mounted Amplifier
Uplink Coverage Gain
0
2
4
6
8
10
12
14
16
18
0 0.2 0.4 0.6 0.8 1Cell Range R (km)
To
talInterfe
rence
I(dB) Link Budget Curve with TMA
Link Budget Curve w/o TMA
I(R) for High_Traffic
I(R) for Low_Traffic
Node B
Feeder
Antenna
Tx / Rx
Duplexer
Duplexer
Tx Rx
TMA
Typical reduction of the required numbeof sites:
~40% for low traffic scenario
~30% for high traffic scenario
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4-RX diversity on Uplink
Uplink Coverage Gain
4-RX diversity on Uplink
Uplink Coverage Gain
Link Budget Curve with 4RxDiv
I(R) for High_Traffic w/o 4RxDiv
I(R) for High_Traffic with 4RxDiv
I(R) for Low_Traffic w/o 4RxDiv
I(R) for Low_Traffic with 4RxDiv
0
1
2
3
4
5
6
7
8
9
10
0 0,2 0,4 0,6
Cell Range R (km)
TotalInterferenceI(dB)
Link Budget Curve w/o 4RxDiv
Typical reduction of the required number
of sites: ~30% for low traffic scenario
~40% for high traffic scenario
Distance d
Rxdiv1 Rxdiv2 Rxdiv3 Rxdiv4
SpaceDiversity
PolarisationDiversity
PolarisationDiversity
Xpolantenna 2
Xpolantenna 1
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0
5
10
15
20
25
30
35
40
45
100 200 300 400 500 600 700 800 900
Throughput NRT 128 (kbps)
Transm
itpower(Watt)
RURAL 7 km
RURAL 5 km
SUBURBAN 1,3 km
URBAN 0,5 km
URBAN DENSE 0,35 km
Capacity
gain
High Power Amplifier
Impact of Node B power on DL capacity
High Power Amplifier
Impact of Node B power on DL capacity
> Negligibleimpact in urbanareas
>Visible gain onlyin low densityrural areas
Transm
itpower(W
att)percarrier
Sector Capacity
RuralRural
UrbanUrban
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0%
10%
20%
30%
40%
50%
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Cell range (km)
Capacityg
ain(%)
From 6.7W per carrier to11.7W per carrier (3 carriers)
From 10W per carrier to 17.5Wper carrier (2 carriers)
From 20W per carrier to 35Wper carrier (1 carrier)
High Power Amplifier
DL Gain in multicarrier configurations - Urban
High Power Amplifier
DL Gain in multicarrier configurations - Urban
20W vs. 35W at antenna connector: NRT 128 in Urban
negligible gain for 1 carrier
small gain for 3 carriers
Uplink
Coveragelimited cell
ranges
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> Performance gain of TX diversityfeature consists of three aspects:
Doubling the TX power by adding a
power amplifier
Reducing the required transmit powerfor each downlink channel (transmit
power raise due to fast fading is
reduced)
TX Diversity on Downlink
Performance Gain
TX Diversity on Downlink
Performance Gain
Improving the required received Eb/N0
(slight reduction for open loop
TxDiv, higher for closed loop TxDiv)6
7
8
9
3 6 10 25 50 120
TargetRxEb/N0(dB)
S eed km/h
Speech 8 kbps, 1 rx antenna, downlink, pedestrian A
Without Tx diversitySTTD
0.8 dB
TEU
PA
TEU
PA
Power Amplifier Antenna
Antenna 1
Antenna 2
20 W
20 W
TX Bus
TX1
TX1div
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0%
2%
4%
6%
8%
10%
12%
14%
16%
18%
20%
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Cell range (km)
Capacitygainb
ydoublingthemax
.downlink
tra
nsmitpower(%) From(20W,1Carrier)To (40W,1Carrier)
TX Diversity on Downlink
Gain on Downlink Capacity - Example
TX Diversity on Downlink
Gain on Downlink Capacity - Example
> Gain highly dependent on diversity technique (open or closed loop)and multipath profile (Pedestrian>>Vehicular)
Pure Diversity gain in capacity: ~8%
Gain through 2nd PA:
dependent on cell range (curve)
Example for typical cell range
(0.55km):
8%+3%=11% total gain
UplinkCoverage
limited
cell
ranges
Example:
STTD - Space-Time transmit diversity (open loop)Vehicular A,NRT 128, Urban,
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Adding a carrier
Uplink coverage
Adding a carrier
Uplink coverage
> Uplink Coverage:
Link Budget curve
stays the same, traffic
curve depends on #
of carriers
0
2
4
6
8
10
12
14
16
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Cell Range R (km)
TotalInt
erferenceI(dB
)
link budget curve
I(Traffic),1 carrier
I(Traffic), 2 Carriers
Carrier config Dense Urban Rural Dense Urban Rural1C -> 2C 5% 10% 20% 20%
2C -> 3C 3% 5% 15% 15%
Low traffic High traffic
UL Coverage gain
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Adding a carrier
Downlink capacity
Adding a carrier
Downlink capacity
t Significant increase of downlink capacity
t Exact gain depends on the hardware configuration (Nb of PA persector, # of carriers, etc) and cell range
t Adding a carrier implies:reducing power per carrier(20W 2x10W) PA
Carrier
Power Amplifier
Antenna
Antenna 1
10 W per carrier
TX
C1
C2
0%
25%
50%
75%
100%
0 0.2 0.4 0.6 0.8
Cell range (km)
Capacitygain(%)
From 1 carrier (20W p.c.)to 2 carriers (10W p.c.)
From 2 carriers (10W p.c.)to 3 carriers (6W p.c.)
Uplink
Coverage
limited cellranges
Uplink
Coverage
limited cellranges
t Adding acarrier is not only a
downlink feature, but will bring
for fixed intersite distance
uplink capacity gain as well
Most powerful enhancement
feature
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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 16 All rights reserved 2002, Alcatel
Deployment strategy
Incumbent Operator
Deployment strategy
Incumbent Operator
Traffic forecast
GSM Cell range=strategic cell radiusGSM Cell range=strategic cell radius
Holes or capacity problems?
Coverage and Capacity analysis
Which limitation?
Apply UL feature
(TMA, 4RXDiv, MUD)
(if not yet used)
Apply DL feature(TxDiv, HPA)
(if not yet used)
Add a carrier(if still available)
Look atnext phase
Start: Phase 0
UL DL both UL&DL
YES
NO
Maximize the re-use of existing GSM sites
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Deployment strategy
Greenfield Operator
Deployment strategy
Greenfield Operator
Evaluate Cell Ranges
(for all traffic phases and scenarios)
Identify suitable strategicranges
Apply possible deploymentscenarios
(service deployment,advanced features upgrade)
Build business cases
Select the solution that best fits
your business requirements
There is no unique solution
for strategic cell range and
deployment strategy, the finalchoice is an (individual)
strategic decision!
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ConclusionConclusion
> The upgrade plan is not finished at dimensioning stage:
continuous adaptation is required through
Monitoring traffic
Regularly updating the traffic forecast
Adjusting the upgrade strategy
>Analytical dimensioning techniques can be used for
predicting and avoiding potential problems due to cell
breathing (upgrade strategy)
> The network evolution can be considered already at
dimensioning stage
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Yannick DUPUCH
UMTS Project Manager
Mobile Networks [email protected]
Thank you for your attentionThank you for your attention