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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 inWireless Networks 2002
July 3rd - 5th, 2002
IEEE Workshop on Applications and Services inWireless Networks 2002
July 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
Agenda Agenda
�Facing the Multimedia traffic increase
� Cell breathing and cell range evolution
� Strategic Cell Radius
�Upgrade your Network
� Advanced Radio Features
� Elaborating the deployment strategy
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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 3 All rights reserved © 2002, Alcatel
� Various data rates (from Voice 12.2kbps up to 384Kbps)
� Various QoS and GoS (blocking, delay, throughput, BLER)
� Various connection types (Real Time and Non Real Time)
� Various traffic asymmetry and activity behaviour.
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 BreathingMultiservice Traffic characteristicCell BreathingMultiservice Traffic characteristic
MultiserviceMultiserviceMultiservice
Different Data ratesDifferent Data ratesDifferent Data rates
Different SensitivitiesDifferent SensitivitiesDifferent Sensitivities
Different FootprintsDifferent FootprintsDifferent Footprints
Voice and Low Data Rate (eg up to 64kb/s)
Medium Data Rate(eg 144kb/s)
High Data Rate (eg 384kb/s)
� Different footprints for different services� Different footprints for 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:� Blue: Voice Only� Green: Voice and CS64� Red: Voice, CS 64 and PS384
Cell BreathingMultiservice EnvironmentCell BreathingMultiservice Environment
1000 subs/km2 - Year 5
300 subs/km2 - Year 3
100 subs/km2 - Year 1Seamless Coverage
Coverage for each service is traffic
dependent� 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 predictionIterative Link Budget DimensioningFrom traffic forecast to coverage predictionIterative 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
CellCellRangeRangeC
ell R
an
ge
ass
um
pti
on
Cell R
an
ge
Cell R
an
ge
ass
um
pti
on
ass
um
pti
on
Multiservice Trafficinputs
UL analysis
DL analysis
UL traffic
DL traffic
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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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 6 All rights reserved © 2002, Alcatel
Strategic cell radiusFixing a time variant parameterStrategic cell radiusFixing a time variant parameter
> Strategic cell
range will define
the deployedinter-sitedistance per
environment
Dense Urban / Cell range = f(Phases)
0.55
0.6
0.65
PHO PH1 PH2 PH3Phases
Cel
l ran
ge (k
m)
Voice with 1 carrier
Traffic increases
Example ofstrategic cell radius
�
�
�
�
�
�
�
Site
Site
Site
Site
Site
Site
Site
Seamless coverage
Holes in coverage
1.5xR
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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 7 All rights reserved © 2002, Alcatel
Advanced FeaturesAvoiding Cell Breathing problems by timely upgradeAdvanced FeaturesAvoiding Cell Breathing problems by timely upgrade
> Anticipate holes through coverage prediction
> Avoid holes by timely upgrade
� In case of Downlink limitation
� TX Diversity
� High power amplifier
� In case of Downlink limitation
� TX Diversity
� High power amplifier
� In case of Uplink limitation
� Tower Mounted Amplifier (TMA)
� 4 Way RX Diversity
� Multi User Detection, MUD
� In case of Uplink limitation
� Tower Mounted Amplifier (TMA)
� 4 Way RX Diversity
� Multi User Detection, MUD
�For either Uplink or Downlink
limitation:
� Adding carriers
� Sectorisation
� Adding sites (densification)
� Smart antennas
�For either Uplink or Downlink
limitation:
� Adding carriers
� Sectorisation
� Adding sites (densification)
� Smart antennas
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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 8 All rights reserved © 2002, Alcatel
Tower Mounted AmplifierUplink Coverage GainTower Mounted AmplifierUplink Coverage Gain
0
2
4
6
8
10
12
14
16
18
0 0.2 0.4 0.6 0.8 1
Cell Range R (km)
Tota
l In
terf
ere
nce
I (
dB
) Link Budget Curve with TMALink Budget Curve w/o TMAI(R) for High_TrafficI(R) for Low_Traffic
Node B
Feeder
Antenna
Tx / Rx
Duplexer
Duplexer
Tx Rx
TMA
Typical reduction of the required numberof sites:
– ~40% for low traffic scenario– ~30% for high traffic scenario
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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 9 All rights reserved © 2002, Alcatel
4-RX diversity on UplinkUplink Coverage Gain4-RX diversity on UplinkUplink Coverage Gain
Link Budget Curve with 4RxDiv
I(R) for High_Traffic w/o 4RxDiv
I(R) for High_Traffic with 4RxDivI(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 0,6Cell Range R (km)
Tot
al In
terf
eren
ce I
(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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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 10 All rights reserved © 2002, Alcatel
0
5
10
15
20
25
30
35
40
45
100 200 300 400 500 600 700 800 900
Throughput NRT 128 (kbps)
Tran
smit
pow
er (W
att)
RURAL 7 km
RURAL 5 km
SUBURBAN 1,3 km
URBAN 0,5 km
URBAN DENSE 0,35 km
Capacity gain
High Power AmplifierImpact of Node B power on DL capacityHigh Power AmplifierImpact of Node B power on DL capacity
> Negligibleimpact in urbanareas
> Visible gain onlyin low densityrural areas
Tran
smit
pow
er (W
att)
per c
arrie
r
Sector Capacity
RuralRural
UrbanUrban
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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 11 All rights reserved © 2002, Alcatel
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)
Cap
acity
gai
n (%
)
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 AmplifierDL Gain in multicarrier configurations - UrbanHigh Power AmplifierDL 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
UplinkCoverage
limited cellranges
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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 12 All rights reserved © 2002, Alcatel
> Performance gain of TX diversityfeature consists of three aspects:
� Doubling the TX power by adding apower amplifier
� Reducing the required transmit powerfor each downlink channel (transmitpower raise due to fast fading isreduced)
TX Diversity on DownlinkPerformance GainTX Diversity on DownlinkPerformance 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
Targ
et R
x Eb
/N0
(dB)
Speed (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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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 13 All rights reserved © 2002, Alcatel
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)
Cap
acity
gai
n by
dou
blin
g th
e m
ax. d
ownl
ink
tran
smit
pow
er (
%)
From(20W,1Carrier)To (40W,1Carrier)
TX Diversity on DownlinkGain on Downlink Capacity - ExampleTX Diversity on DownlinkGain 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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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 14 All rights reserved © 2002, Alcatel
Adding a carrierUplink coverageAdding a carrierUplink coverage
> Uplink Coverage:
• Link Budget curvestays the same, trafficcurve 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)
Tot
al In
terf
eren
ce I
(dB
)
link budget curveI(Traffic),1 carrierI(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 trafficUL Coverage gain
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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 15 All rights reserved © 2002, Alcatel
Adding a carrierDownlink capacityAdding a carrierDownlink capacity
� Significant increase of downlink capacity
� Exact gain depends on the hardware configuration (Nb of PA persector, # of carriers, etc…) and cell range
� Adding a carrier implies:reducing power per carrier(20W � 2x10W) PA
Carrier
Power Amplifier
Antenna
Antenna 1
10 W per carrier
TXC1
C2
0%
25%
50%
75%
100%
0 0.2 0.4 0.6 0.8Cell range (km)
Cap
acity
gai
n (%
)
From 1 carrier (20W p.c.)to 2 carriers (10W p.c.)
From 2 carriers (10W p.c.)to 3 carriers (6W p.c.)
UplinkCoverage
limited cellranges
UplinkCoverage
limited cell ranges
� Adding a carrier is not only adownlink feature, but will bringfor fixed intersite distanceuplink capacity gain as wellMost powerful enhancementfeature
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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 strategyIncumbent OperatorDeployment strategyIncumbent 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 at next phase
Start: Phase 0
UL DL both UL&DL
YES
NO
Maximize the re-use of existing GSM sites
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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 17 All rights reserved © 2002, Alcatel
Deployment strategyGreenfield OperatorDeployment strategyGreenfield 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 fitsyour business requirements
There is no unique solutionfor strategic cell range and
deployment strategy, the finalchoice is an (individual)
strategic decision!
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How to minimize the impact of cell breathing effect on UMTS network / July 4th / 18 All rights reserved © 2002, Alcatel
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 forpredicting and avoiding potential problems due to cellbreathing (� upgrade strategy)
> The network evolution can be considered already atdimensioning stage
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Yannick DUPUCH
UMTS Project ManagerMobile Networks [email protected]
Thank you for your attentionThank you for your attention