cellular network planning and optimization part8

8/6/2019 Cellular Network Planning and Optimization Part8

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Cellular NetworkPlanning andOptimization

Part VIII:WCDMAlink budgetJyriHmlinen,

Communications andNetworking Department,TKK,15.2.2008


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WCDMANetwork planning

High level objectives fortheplanning process

Coverage Guaranteethenetworkabilitytoensuretheavailabilityoftheservicein

theentireservicearea.

Capacity Tosupportthesubscribertrafficwithsufficientlylowblocking anddelay

Quality LinkingthecapacityandthecoverageandstillprovidetherequiredQoS.

Costs Toenableaneconomicalnetworkimplementationwhentheserviceis

establishedandacontrolled networkexpansionduringthelifecycleof

thenetwork.


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WCDMAvs GSM,Network planning

Multiserviceenvironment

Bitratesusuallyfrom8to384kbit/s

Bitrateswitching

Multi-RABs

Trafficclasses

Errorrates,10%FERto10-6 BER

Delaysensitivity,from100msuptoseconds

AsymmetricULandDLtraffic

Commonchanneldatatraffic

Airinterface

Capacityandcoveragecoupled

together Neighboringcellscoupledvia

interference

Receiverperformancedependson

bitrate,environment

Softhandover&FastPowerControl

Commonsharedresources


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CoveragePlanningandSiteSelection

ParameterPlanning

Propagationmeasurements

Coverageprediction

SiteacquisitionCoverage

optimisation

ExternalInterferenceAnalysis

NetworkConfigurationandDimensioning

DEFINITION PLANNINGandIMPLEMENTATION

TrafficdistributionServicedistributionAllowedblocking/queuingSystemfeatures

IdentificationAdaptation

Area/Cellspecific

Handoverstrategies

Maximumnetworkloading

OtherRRM

NetworkOptimisation

O&M

Surveymeasurements

Statisticalperformanceanalysis

QualityEfficiencyAvailability

CapacityRequirements

Requirementsandstrategyforcoverage,qualityandcapacity,perservice


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CoveragePlanningandSiteSelection

ParameterPlanning

Propagation

measurementsCoverageprediction

Siteacquisition

Coverageoptimisation

Exte

Ana

NetworkConfigurationandDimensioning

DEFINITION PLEMENTATION

Trafficdistribution

ServicedistributionAllowedblocking/queuing

Systemfeatures


Area/Cellspecific

Handoverstrategies


OtherRRM

NetworkOptimisation

O&M

Surveymeasurements



CapacityRequirements

Requirements

andstrategyforcoverage,qualityandcapacity,

perservice

Multipleservices

Coverageandcapacitycoupling

Multipleservices



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ction

ParameterPlanning

Propagation

measurementsCoverageprediction

Siteacquisition ExternalInterference

Analysis

NetworkConfiguratiandDimensioning

DEFINITIO ION

TrafficdistributionServicedistributionAllowedblocking/queuing

Systemfeatures


Area/Cellspecific

Handoverstrategies


OtherRRM

NetworkOptimisation

O&M

Surveymeasurements



Capacitrements

Requirements

andstrategyforcoverage,

ality andpacity,r

service

ExperienceonserviceusagefromGSM,with

GPRSandEDGEGSM1800propagationmeasurements

GSMco-siting

GSMfor

coverageextension



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Recall:RABconcept

TE MT UTRAN CNIuEDGE

NODE

CN

Gateway

TE

UMTS

End-to-EndService

TE/MTLocal

BearerService

UMTSBearerService ExternalBearer

Service

UMTSBearerService

RadioAccessBearerService CNBearerService

Backbone

BearerService

IuBearer

Service

RadioBearer

Service

UTRAFDD/TDD

Service

Physical

BearerService


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Recall:Servicetypes

Typical services associated with theRABs ConversationalSpeech:AdaptiveMultiRate(AMR)

speech ConversationalCSdata: VideoTelephony Streaming:Video,audio streaming Interactivedata:Corporate access,webbrowsing,

WAPetc Background data:E-mails,internetaccess,

downloads Multi-RAB:e.g.speech +e-mail,speech +internet

access,etc


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Whats usually available

Typical first releases

ofR99WCDMAConversational Speech

Multi-RAB

Speech

Conversational CSData

Interactive

4,75-12,2kbpsAMRCS

64kbpsCS

Streaming

57.6kbps CS

64/64kbps PS

64/128kbps PS

64/256kbps PS

PS64/64->128/384kbps

Typical 2004/5releases

ofWCDMA(R4)

Combinations ofAMR

speech andup to64/384kbps

PSInteractive

Multi-RABCombinations ofCS

conversational

dataandup to64/384kbps

PSInteractive/Multiple PS

Interactive

Conversational PSData 64->128kbps PS(R5)HS-DSCH(HSDPA) 1.8->3.6Mbps(R5,1H2006)

E-DCH(HSUPA)0.7->1,5Mbps(R6)

ConversationalCSData

ConversationalSpeech

Streaming

Interactive

Multi-RAB

ConversationalCSData

ConversationalSpeech

Streaming

Interactive

Multi-RAB

12.2kbpsCircuitSwitched

64kbpsCircuitSwitched

57.6kbpsCircuitSwitched

VariableratePacketSwitchedUL/DL64/64,64/128,64/384

CombinationofConversationalSpeechandInteractive64/64


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Traffic types

RTguaranteed bit-rate &delay traffic isthemostdemanding type oftraffic forcell design(especially highbit-rate) Conversational class circuit switched voice (not demanding due to

slow bit-rate) Conversational class circuit switched videotelephony (more

demanding formaintain QoS than tothecell design,CSbearer notutilising capacity optimally)

Streaming class circuit andpacket switched data(very demanding,especially high-bit rate packet switched)

NRTIntercative/Background traffic isless demandingtype oftraffic forcell designdue tobursty andnon-guaranteed nature

So far inlive3Gnetworks,theamount ofvideotelephony andstreaming packet switched dataisminimal compared toIntercative/Background traffic andvoice


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Traffic dimensioning When predicting thetraffic for

3Gplan,issues should beconsidered as

Terminalpenetration (2G/3G)

Operator market share

Subscriber prediction

Amount ofroamers

User profiles

Serviceusage perprofile

0%

20%

40%

60%

80%

100%

2004 2005 2006 2007 2008 2009

Highuptakescenario

3.G2.5G

2G

2004 2005 20062007

20082009

010

20304050

607080

90100110120

130140150

160170180190

200

Totaltrafficin

MBperm

onth

Years

Trafficgrowthpermonthavg.user

Datausage

Voice


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Traffic dimensioning DuetoCDMA-characteristicsand

multi-servicenatureofWCDMA,withoutaccuratetrafficmodelingandpredictionsthecapacityandcoverage

ofthenetworkisdifficulttoplan. Themodelingcanbebasedonthe

knowledgeofGSM/GPRSandinternetusagepatternsaswellason

assumptionsofserviceusage

Predictingtheamountofusageandusagelocationsisofhighimportance,

becauseofthefluctuatingnatureofthetraffic>simulationswithvarioustrafficscenariosneeded.

Userscenarios/profilesshouldbecreatedtogetherwithbusinessplanningandshouldsupporttheselectedstrategyinthedimensioning


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Traffic dimensioning example forinteractive class

Amountofactiveusers

Numberof

subscribers

Amountofwebpagestobe

downloadedpersubscriber

Payload

Sessionefficiency,incl overheadand

retransmissions

MaximumRABbitrate

Offeredtraffic

sessionpeak

bps

sessionpeak

pagessubs

RA

RYnnM

=

3600


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Traffic dimensioning inplanning tools

Typical traffic dimensioning ina3Gplanning tool


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Traffic dimensioning inplanning tools

InPSconnectionsassociated parametersneed tobe decided perservice.Example:


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WCDMANetwork dimensioning

Asmost UMTSnetworks are built ontopofexisting GSMnetworks,the

process isfocused toestimate what level ofcoverage/capacity can be

achievied with re-use ofGSMgrid

Typically initial dimensioning produces therough esitimation on

needed equipment amount &configuration foraservice area


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Eb/NoNodeB

TX-power

Losses(cable,feeders

etc.)

NodeBantenna

gain

Pathloss SoftHand-overgain

Terminalantenna

gain

Terminallosses

(e.g.bodyloss)

Ec/IoInterferencemargin

Dependsone.g.amountofusersand

distribution

Processinggain

Dependsonusedservicei.etheRAB(radioaccessbearer)

WCDMALink Budget


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WCDMALink Budget

Due todifference inEb/Norequirement,processing gain andreceiver sensitivity foreach user,thecalculated pathloss (andcell size)isdifferent foreach user.

InWCDMAtheNode BandUEalso need touse more power

forthedemanding users,especially if connecting from adistance (large pathloss)

AMRvoice

384kbps

Asarule ofthumb

coverage for128kbpsNRTPSservice innormalloading conditions equalsGSM1800voice coverage for384kbps

NRTPSservice innormalloading conditions is~10dBworse than AMR12.2voice


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Link budget,12.2kbps speech12.2kbpsvoice,DL 12.2kbpsvoice,UL

Targetload 0.75 0.5

Transmittercharacteristics Totaltransmitterpower 20 W 0.125 W

TransmitterpoweronTCH 0.348718 W 0.125 W

25.42474 dBm 20.9691 dBm

TXantennagain 17.42531 dBi 0 dBi

TXcableloss 2 dB 0 dBTXBodyloss 0 dB 2 dB

TransmitterEIRP 40.85005 dBm 18.9691 dBm

Receivercharacteristics RXantennagain 0 dBi 17.42531 dBi

andmargins Thermalnoisedensity -174 dBm/Hz -174 dBm/Hz

Receivernoisefigure 8 dB 5 dB

Receivernoisedensity -166 dB -169 dBReceivernoisepower -100.157 dBm -103.157 dBm

Spreadinggain 24.97971 dB 24.97971 dB

RequiredEb/No 7 dB 5 dB

Interferencemargin 6.0206 dB 3.0103 dB

Requiredsignalpower -112.116 dBm -120.126 dBm

RXCableloss 0 dB 2 dB

RXBodyloss 2 dB 0 dBDiversitygain 0 dB 3 dB

Fastfadingmargin 0 dB 3 dB

Softhandovergain 1 dB 2 dB

Coverageprobability(celledge) 0.9 0.9

Shadowfadingstddeviation 6 dB 6 dB

ShadowFadingMargin 7.5 dB 7.5 dB

Indoorpenetrationloss 0 dB 0 dBAllowedpropagationloss 146.4659 dB 149.0205 dB


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Linkbudget,TXcharacteristics

12.2kbpsvoice,DL 12.2kbpsvoice,UL

Targetload 0.75 0.5



25.42474 dBm 20.9691 dBm

TXantennagain 17.42531 dBi 0 dBiTXcableloss 2 dB 0 dB

TXBodyloss 0 dB 2 dB


Network load assumption fordimensionning (targetloading) Thetarget load level ofthenetwork should be based onasaccurate predictions ofservice&traffic mixdistribution andgrowth aspossible


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Targetload

Target load%

Urban macro cells 50-60% (demanding traffic &user profiles,buildings restrict cell dominance,shadowing)

Urban micro cells 70% (small cells,traffic hotspots andindoor) Rural 30-40% (coverage important,lower traffic,different user

profiles)

Not higher than 75% (ULhard tomanage,interference explodes)

Too high initial target can result intoo dense network (expensive)if

thetraffic or use ofresources isestimated wrongly.Network canalso be hard tomanage interms ofcell overlapping celldominance tobe guaranteed.

Too low initial target can result tocoverage holes andcapacityproblems,if thetraffic proves tobe higher than predicted orresources are utilised differently.


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TXpowerinBS

Recallthecontroloverhead

ThemaximumnumberofusersforacertainservicecanbecomputedusingDLloadequations(tobeexplained

later) ItisimportanttonoticethatbydecreasingtheDLload

targettheTCHpowercanbeincreasedandcellcoverageincreased.


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RXcharacteristicsReceivercharacteristics RXantennagain 0 dBi 17.42531 dBi



Receivernoisedensity -166 dB -169 dB

Receivernoisepower -100.157 dBm -103.157 dBm

Processinggain 24.97971 dB 24.97971 dB

RequiredEb/No 7 dB 5 dBInterferencemargin 6.0206 dB 3.0103 dB



RXBodyloss 2 dB 0 dB

Diversitygain 0 dB 3 dB

Fastfadingmargin 0 dB 3 dBSofthandovergain 1 dB 2 dB




Indoorpenetrationloss 0 dB 0 dB

Receivernoisefigureisusuallybetween5to9dBandBShavebetterNF.Precisevalueofthisparameterisproductspecific.


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Receivernoisedensity(perHz)isasumofreceivernoisefigureandthermalnoisedensity.Receivernoisepowerisequaltoreceivernoisedensityxchiprate


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Processinggainisthechipratedividedbyuserbitrate


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Eb/Novaluescanbeobtainedbylinksimulations.Therearealsoinformativevaluesgivenin3GPPspecifications.Eb/Novalues areusually provided by thenetwork vendor


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Eb/No

WhileEc/Ioisdefinedbefore thesignalde-spreadingoperationandEb/Noafterde-spreading.

Ec/Io can be be determined forthesignal intheair SoEb/Nodependsontheservice(bitrate,CS/PS,

receivingend)&vendor

Ec/Ioisserviceindependent

Typical Eb/Novalues AMR12.2kbps speech (BLER


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Interferencemargin

Receiverbackgroundnoiseincreasesinproportiontotheincreaseoftheusers

Thisneedstotakenintoaccountinthelinkbudgetwithaspecificinterferencemargin,which

isdirectlyrelatedtotheloading


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Interferencebindsthecapacityandcoverage

0

0,2

0,4

0,6

0,8

1

1,2

0 0,2 0,4 0,6 0,8 1

Cellloading

Cellrang

eThemoretrafficisbroughttothecell,moreinterferenceisproduced

WhentheinterferencegrowsinthecellthemostfarawayterminalfromtheNodeBcannotwintheinterferenceevenwiththemaximumTX-power

Newuserscannot

accessthecellfromdistance

Cellrangedecreases

InordertowintheinterferencetheterminalshavetoincreasetheirTX-power

Interference margin


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Fastfadingmargin

PCheadroom isanoverhead onthetransmit power aterminal needs tomake intheUL.This overheadensures that theULPCisable tocompensate fordeep

fades atcell border PCHeadroom isafunction ofUEspeed,andthe

overhead islargest forrelatively slowly moving UEs(


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Insofthandovertwosignalsarecombined


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Soft/Softerhandover

Soft/Softer Handover gain develops from combining ofsignals either innode Bs RAKEor RNC.InDownlinksignals are combined interminals RAKEreceiver

Uplink SoftHandover gain comes from RNCframeselection combining.Gain isnot achieved asconcretegain inradiointerface,but asmore stable power control.

InUplink Softer HOmaximum ratio combining isperformed innode Bs RAKE=>gain 1-3dB

Downlink SoftHO:n maximum ratio combining isperformed interminals RAKE=>gain 1-2dB


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Shadowfadingmarginhasbeendiscussedpreviously,butletsrecallsomeissues


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Shadow fading margin (SFM)

SFMisneededbecausethebuildingsandotherobstaclesbetweentheUE andNode B arecausingchangesinthereceivedsignallevelatthereceiver

SFMistakenintoaccountintheWCDMAlinkbudgettoassurea

minimumsignallevelwiththewantedprobability According tomeasurements inliveUMTSnetwork,it has been noticed

that thepractical SFMandstandard deviation values are nearly thesame forWCDMAandGSM

Network area/Parameter

Standard deviation

Shadow fading

marginArea

probabil

ity 90%

Area

probabil

ity 95%

Dense urban /Urban

8,5 dB 6 dB 9,5 dB

Sub-urban 7,2 dB 4,7 dB 7,6 dB

Rural 6,5 dB 3,9 dB 6,6 dB

Somevaluesthatareusedbasedon

measurements


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Cellrange

Allowedpropagationloss 146.4659 dB 149.0205 dB

Range(Okumura-Hatapathlossmodel) Unit

Carrierfrequency 2100 MHz

BSantennaheight 25 m

MSantennaheight 1.5 mParameterA 46.3

ParameterB 33.9

ParameterC 44.9

MSantennagainfunction(largecity) -0.00092

Pathlossexponent 3.574349

Pathlossconstant 137.3351 dBDownlinkrange 1.800742 km

Uplinkrange 2.12287 km

Cellrange 1.800742 km

ItseemsthatWCDMAandGSM1800admitprettysamespeech

coverage(recallthatGSM1800rangewereround1.58km).Actuallyifwewouldhaveusedthesamecablelossthencellrangewouldhavebeen1.58kmalsoforWCDMA.Yet,WCDMAlinkbudgetcontainsmuchmoreparameters=>morepotentialerrorsourcesindimensioning.


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Linkbudget,384kbpsdata384kbpsdata,DL 384kbpsdata,UL

Targetload 0.75 0.5



37.53328 dBm 23.9794 dBm

TXantennagain 17.42531 dBi 0 dBi

TXcableloss 2 dB 0 dBTXBodyloss 0 dB 0 dB


Receivercharacteristics RXantennagain 0 dBi 17.42531 dBi



Receivernoisedensity -166 dB -169 dBReceivernoisepower -100.157 dBm -103.157 dBm

Processinggain 10 dB 10 dB

RequiredEb/No 7 dB 3 dB

Interferencemargin 6.0206 dB 3.0103 dB



RXBodyloss 0 dB 0 dBDiversitygain 0 dB 3 dB






Indoorpenetrationloss 0 dB 0 dBAllowedpropagationloss 143.5947 dB 140.0511 dB

TX


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TXpower

384kbpsdata,DL 384kbpsdata,UL

Targetload 0.75 0.5



37.53328 dBm 23.9794 dBm

TXantennagain 17.42531 dBi 0 dBiTXcableloss 2 dB 0 dB

TXBodyloss 0 dB 0 dB


RecallthecalculationofTCHtransmissionpower

Nowmaximumnumberofusersisonly4=>BSTXpoweronTCHishigh

usersofnumberMaximumtargetLoad

powerTXTotal)overheadControl1(

,

=

TCHTX

P

Dataterminalmayhave

higherTXpower

R i h i i


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ReceivercharacteristicsReceivercharacteristics RXantennagain 0 dBi 17.42531 dBi





Processinggain 10 dB 10 dB







Softhandovergain 1 dB 2 dBCoverageprobability(celledge) 0.9 0.9




ProcessinggainissmallerduetohigherdatarateEb/NoinULisalsoslightlysmaller.


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Cellrange

Inpreviouslinkbudgetsindoorpenetrationlosswere0dB.Ifweassume20dBpenetrationloss

(usualvalue)then

Downlinkrange 0.41265 km





Downlinkrange 0.496488 km



12.2kbpsspeech

384kbpsdata

Inter-sitedistance(3sectorcell)=3xrange.Hence,inter-sitedistancesare1488mforspeechand984mfor384kbpsdata(UL).Inpractise inter-sitedistancesareevensmallerinurbanareasduethe

morepessimistic(realistic)parameters.

cellular network planning and optimization part8

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