how to minimize the impact of cell breathing

7/27/2019 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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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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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


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


4-RX diversity on Uplink


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


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)


DL Gain in multicarrier configurations - Urban


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


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)


Gain on Downlink Capacity - Example


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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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

how to minimize the impact of cell breathing

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