LTE Link Budget

ITU/BDT Arab Regional Workshop on 4G Wireless Systems - Tunisia 2010

ITU/BDT Arab Regional Workshop onITU/BDTArab Regional Workshopon4GWirelessSystems

LTETechnology

Session5:LTETechnology PerofrmanceEvaluationEvaluation

Speakers M.Lazhar BELHOUCHETM Hakim EBDELLIM.HakimEBDELLI

Date 27 29January 2010

www.cert.tn1 LTETechnology Perofrmance Evaluation


Agenda

FrequencyBandsandTypicaldeploymentareas Layer1PeakBitRates TerminalCategories ReferenceSensitivity LinkBudgets Propagationmodel Uplink link budgetUplinklinkbudget Downlinklinkbudgets ComparisonbetweenGSM/HSPA/LTE Latency LTERefarmingtoGSMSpectrum

i i i i

www.cert.tn2

CapacityDimensioning

LTETechnology Perofrmance Evaluation


Introduction

Performanceevaluation:LTEcapabilitiesfromtheendusersandfromtheoperatorspointofviewp p

Theoperatorisinterestedinthenetworkefficiency: howmanycustomerscanbeserved, howmuchdatacanbeprovidedandhowmanybasestationsitesare

required.

Th d li i f d d Theenduserapplicationperformancedependson: availablebitrate, latency and latencyand seamlessmobility



FrequencyBands

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FrequencyBands:Typicaldeploymentareas

Europe: Band7:The2.6GHzauctionshavebeenrunninginafewcountriesduring2007and

2008,andcontinueduring2009/2010.

Band8:iscurrentlyusedmostlybyGSM.Thebandisattractivefromacoveragepointofviewduetothelowerpropagationlosses.ThebandcanbereusedforLTEorforHSPA.

Band3:isalsousedbyGSM,butinmanycasesBand3isnotasheavilyusedbyGSMasBand8.ThatmakesrefarmingforLTEsimpler.

Digitaldividend USA:Bands4,12,13,14and17.Bands2and5canbeusedforLTErefarming. Japan:Bands1,9,11and18. LTEdeploymentsgloballywilluseseveraldifferentfrequencybandsfromthe

start.



LTE Technology Perofrmance Evaluation

PERFORMANCEEVALUATIONLTETechnology Perofrmance Evaluation



Layer1PeakBitRates

sSubCarrierofNumberHzbits

msSubFramepersymbolsofNumbersMbratebitPeak *)(*

1]/[ =

controlandreferencesignaloverheads: PDCCH:takesonesymboloutof14symbols.ThatistheminimumpossiblePDCCH

allocation The resulting control overhead is 7 1% ( = 1/14)allocation.Theresultingcontroloverheadis7.1%(=1/14).

DownlinkReferenceSignals(RS)dependontheantennaconfiguration:Singlestreamtransmissionuses2RSoutof14inevery3rdsubcarrier,2 2MIMO4symbols and 4 4 MIMO 6 symbols The overhead varies between 4 8% and 14 3%symbolsand4 4MIMO6symbols.Theoverheadvariesbetween4.8%and14.3%.

OtherdownlinksymbolsOverhead:synchronizationsignal,PBCH,PCFICH,andonegroupofPHICH.TheoverheaddependsontheBWrangingfrombelow1%at20MHz to approximately 9% at 1 4 MHzMHztoapproximately9%at1.4MHz.

Uplinkreferencesignalstake1symboloutof7symbolsresultinginanoverheadof14.3%=1/7.



Layer1PeakBitRates Cont.

BWRB/Subcarriers

/Modulationandcoding

Bits/symbol

MIMOusage 1.4MHz6/72

3.0MHz15/180

5.0MHz25/300

10MHz50/600

15MHz75/900

20MHz100/1200

QPSK1/2 1 Singlestream 0.9 2.2 3.6 7.2 10.8 14.4

16QAM1/2 2 Singlestream 1.7 4.3 7.2 14.4 21.6 28.8


64QAM3/4 4.5 Singlestream 3.9 9.7 16.2 32.4 48.6 64.8


64QAM3/4 9 2 2MIMO 7.8 19.4 32.4 64.8 97.2 129.6

64QAM1/1 12 2 2MIMO 10.4 25.9 43.2 86.4 129.6 172.8Q /

64QAM1/1 24 4 4MIMO 20.7 51.8 86.4 172.8 259.2 345.6

Downlink peak bit rates (Mbps)


p ( p )


Layer1PeakBitRates Cont.

BWRB/Subcarriers

Modulation Bits/ MIMO usage 1 4 MHz 3 0 MHz 5 0 MHz 10 MHz 15 MHz 20 MHzModulationandcoding

Bits/symbol

MIMOusage 1.4MHz6/72

3.0MHz15/180

5.0MHz25/300

10MHz50/600

15MHz75/900

20MHz100/1200

QPSK1/2 1 Singlestream 0.9 2.2 3.6 7.2 10.8 14.4



16QAM 1/1 4 Single stream 3 5 8 6 14 4 28 8 43 2 57 616QAM1/1 4 Singlestream 3.5 8.6 14.4 28.8 43.2 57.6

64QAM3/4 4.5 Singlestream 3.9 9.7 16.2 32.4 48.6 64.8


Uplink peak bit rates (Mbps)



TerminalCategories

Category1 Category2 Category3 Category4 Category5

Peak ratedownlink (approximately) 10Mbps 50Mbps 100Mbps 150Mbps 300Mbps

Peak rateuplink (approximately) 5Mbps 25Mbps 50Mbps 50Mbps 75Mbps

MaxbitsreceivedwithinTTI 10296 51024 102048 149776 299552

MaxbitstransmittedwithinTTI 5160 25456 51024 51024 75376

RFbandwidth 20MHz 20MHz 20MHz 20MHz 20MHz

Modulation downlink 64QAM 64QAM 64QAM 64QAM 64QAMModulationdownlink 64QAM 64QAM 64QAM 64QAM 64QAM

Modulationuplink 16QAM 16QAM 16QAM 16QAM 64QAM

Receiverdiversity Yes Yes Yes Yes Yes

MIMOdownlink Optional 2 2 2 2 2 2 4 4



ReferenceSensitivity

Thereferencesensitivitylevelistheminimummean

kTB:thermalnoiselevel,inunitsofdBm,inthespecifiedbandwidth(B),

receivedsignalstrengthappliedtoantennaportsat

NF:noisefigureforthereceiver, SINRisthesignaltointerferenceplus

noise requirement for the chosenwhichthereissufficientSINRforthespecifiedmodulationscheme to meet a minimum

noiserequirementforthechosenmodulationandcodingscheme,

IMistheimplementationmarginschemetomeetaminimumthroughputrequirementof95%ofthemaximum

3dBrepresentsthediversitygain.

possible.)(3Re dBmIMSINRNFKTBfSens +++=



ReferenceSensitivity

70.00

EUTRAreferencesensitivity

85.00

80.00

75.00

100.00

95.00

90.00

d

B

m

110.00

105.00

1.4 3 5 10 15 20

BandWidth [MHz]BandWidth[MHz]

QPSK1/8 QPSK1/5 QPSK1/4 QPSK1/3 QPSK1/2

QPSK2/3 QPSK3/4 QPSK4/5 16QAM1/2 16QAM2/3

16QAM3/4 16QAM4/5 64QAM2/3 64QAM3/4 64QAM4/5


Q / Q / Q / Q / Q /


LinkBudgets

Thelinkbudgetcalculationsestimatethemaximumallowedsignalattenuationbetweenthemobileandthebasestationgantenna.Themaximumpathlossallowsthemaximumcellrangetobeestimatedwithasuitablepropagationmodel.

Thecellrangegivesthenumberofbasestationsitesrequiredtocoverthetargetgeographicalarea.



LinkBudgets Propagationmodel

Apropagationmodeldescribestheaveragesignalpropagation,anditconvertsthemaximumallowedp p g ,propagationlosstothemaximumcellrange.

Itdependson: Environment:urban,rural,denseurban,suburban,open,forest,sea Distance Frequency atmosphericconditions Indoor/outdoor Indoor/outdoor

Examples:Freespace,WalfishIkegami,OkumuraHata,LongleyRice,Lee,Young

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g y , , g

LTETechnologyPerofrmanceEvaluation


LinkBudgets PropagationmodelCont.

HataModelforUrbanAreas:)log(*)]log(*556944[)log(*8213)log(*16265569 dhChfLu ++=

Forsmallormediumsizedcity,)log()]log(55.69.44[)log(82.13)log(16.2655.69 dhChfLu BHB ++=

)log(*56.1*)7.0)log(*1.1(8.0 fhfC MH += Forlargecities,

)log(56.1)7.0)log(1.1(8.0 fhfC MH +

200150,1.12))*54.1(log(*29.8 fifhM

=

1500200,97.42))*75.11(log(*2.3200150,1.12))54.1(log(29.8

fifhfifh

CM

MH p

Parameters Unit Significance Parameters Unit SignificanceLu dB PathlossinUrbanAreas f MHz FrequencyofTransmissionhB m HeightofbasestationAntenna CH dB Antenna heightcorrectionfactorhM m HeightofmobilestationAntenna d km DistancebetweenBasestationandMS



LinkBudgets PropagationmodelCont.

CoverageevaluationwillbebasedonthetheOk H t ti d l ith thOkumuraHatapropagationmodelwiththeparametersshownbelow:

Urban indoor Suburban indoor Rural outdoor Rural outdoor fixedBasestationantennaheight(m) 30 50 80 80Mobileantennaheight(m) 1.5 1.5 1.5 5Mobileantennagain(dBi) 0 0 0 0Slowfadingstandarddeviation(dB) 8 8 8 8Locationprobability 95% 95% 95% 95%Correctionfactor(dB) 0 5 15 15( )Indoorloss(dB) 20 15 0 0Slowfadingmargin(dB) 8.8 8.8 8.8 8.8



UplinklinkbudgetsGSMvoice HSPA LTE

Datarate(kbps) 12.2 64 64Transmitter UE

( )

Source :

LTE for UMTS a Maxtxpower(dBm) 33 23 23b Txantennagain(dBi) 0 0 0c Bodyloss(dB) 3 0 0d EIRP(dBm) 30 23 23

OFDMA and SC-FDMA Based Radio AccessHarri Holma and Antti Toskala

Receiver BTS/NodeB/eNBe NodeBnoisefigure(dB) 2 2f Thermalnoise(dB) 108.2 118.4g Receivernoise(dBm) 106.2 116.4g ( )h SINR(dB) 17.3 7i Receiver sensitivity 114 123.4 123.4j Interferencemargin(dB) 0 3 1k Cable loss (dB) 0 0 0k Cableloss(dB) 0 0 0l Rxantennagain(dBi) 18 18 18m Fast fademargin (dB) 0 1.8 0n Softhandovergain(dB) 0 2 0

M i th l 162 161 6 163 4


Maximumpathloss 162 161.6 163.4


DownlinklinkbudgetsDownlink GSMvoice HSPA LTEDatarate(kbps) 12.2 1024 1024Transmitter Node B

Source :

LTE for UMTS a Txpower(dBm) 44.5 46 46b Txantennagain(dBi) 18 18 18c Cableloss(dB) 2 2 2d EIRP (dBm) 60 5 62 62

OFDMA and SC-FDMA Based Radio AccessHarri Holma and Antti Toskala

d EIRP(dBm) 60.5 62 62Receiver UE

e UEnoisefigure(dB) 7 7f Thermalnoise(dB) 119.7 108.2 104.5g Receivernoisefloor(dBm) 101.2 97.5h SINR(dB) 5.2 9i Receiversensitivity(dBm) 104 106.4 106.5j Interferencemargin(dB) 0 4 4j g ( )k Controlchanneloverhead(%) 0 20 20l Rxantennagain(dBi) 0 0 0m Bodyloss(dB) 3 0 0

M i th l 161 5 163 4 163 5


Maximumpathloss 161.5 163.4 163.5


LinkbudgetsComparisonGSM/HSPA/LTE

180

MaximumpathlossvaluesforGSMvoiceandHSPAandLTEdata

170

175

155

160

165

dB

145

150

155

140

GSMvoice HSPA1Mbps/64kbps LTE1Mbps/64kbps

Uplink Downlink



LinkbudgetsComparisonGSM/HSPA/LTE TheLTElinkbudgetindownlinkhasseveralsimilaritieswithHSPAandthe

maximumpathlossissimilar.

h l k h d ff ll f Theuplinkparthassomedifferences:smallerinterferencemargininLTE,nomacrodiversitygaininLTEandnofastfadingmargininLTE.

ThelinkbudgetsshowthatLTEcanbedeployedusingexistingGSMandHSPAsitesassumingthatthesamefrequencyisusedforLTEasforGSMandHSPA.

LTEitselfdoesnotprovideanymajorboostinthecoverage.ThatisbecausethetransmissionpowerlevelsandtheRFnoisefiguresarealsosimilarinGSMandHSPAtechnologies,andthelinkperformanceatlowdataratesisnotmuchdifferentinLTEthaninHSPA.

Thelinkbudgetwascalculatedfor64kbpsuplink,whichislikelynotahighenoughdataratefortruebroadbandservice.IfwewanttoguaranteehigherdataratesinLTE,wemayneedlowfrequencydeployment,additionalsites,activeantennasolutionsorlocalareasolutions.



CellrangeComparison

Theurbancellrangevariesfrom0.6kmto1.4kmandsuburban CellrangeswithOkumuraHata

propagation modelfrom1.5kmto3.4km.

SuchcellrangesarealsotypicallyfoundinexistingGSMandUMTS

100

propagationmodel

gnetworks.

Theruralcaseshowsclearlyhigher cell ranges: 26 km for the

10

K

m

highercellranges:26kmfortheoutdoormobilecoverageandevenupto50kmfortheruralf d ll

1

fixedinstallationat900MHz. 0.1900MHz 1800MHz 2100MHz 2600MHz

Urbanindoor Suburbanindoor

Ruraloutdoor Ruraloutdoorfixed



Differencebetween900MHzand2600MHz

Urban RuralRuralfixedwireless

1:AccordingtoOkumuraHata. 2:Shared1.3mantennafor

/ d dPropagationloss (1) +14dB +14dB +14dB

BTS antenna gain 3 dB (2) 0 dBc 0 dB (3)

900/2600giving15and18dBigainat900vs2600MHz.

3:2.5mantennagiving18dBigainatBTSantenna gain 3dB (2) 0dBc 0dB (3)

BTScable loss (4) +1dB +3dB +3dB

900MHz.

4:Cable1/2.Urban30mandrural100m.

UEantenna gain 5dB (5) 5dB (5) 0dB (6) 5:Basedon3GPPRAN4

contributions.

6:Externalfixedantennaassumed.UEsensitivity (7) 1dB 1dB 1dB

Total +6dB +11dB +16dB

7:UEsensitivitycanbeupto3dBworseat900MHzbutthedifference in practice is less.

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differenceinpracticeisless.

LTETechnology Perofrmance Evaluation


CellrangeLimitation

Theearthscurvaturelimitsthemaximumcellrangetoapproximately40kmwithan80mhighbasestationantennapp y gassumingthattheterminalisatgroundlevel.

ThemaximumcellrangecanbecalculatedwithEquationbelow

Toachieve100kmcellrange,therequiredantennaheightis580m!!!

R = 8650 km hRdR +=+ 222 )((Effective earth radius for radio propagation is4/3 larger than real radius)

RdRh

hRdR

+=+=+

22

)(



Latency

Userplanelatencyisrelevantfortheperformanceofmanyapplications.pp

Thereareseveralapplicationsthatdonotrequireaveryhighdatarate,buttheydorequireverylowlatency:voice,realtimegaming,interactiveapplications.



Latency:Endtoenddelaybudget

Delaycomponent Delayvalue

Transmissiontimeuplink +downlink

2ms

Onaverage,thepacketneedstowaitfor0.5msforthestartofthenextframedownlink

Bufferingtime(0.5transmissiontime)

2 0.5 1ms=1ms

Retransmissions10% 2 0.1 8ms=1.6ms

frame.

Theretransmissionstake8msatbest theassumedretransmission

Uplink scheduling request 0.5 5ms=2.5ms

Uplink scheduling grant 4ms

UE d l i d 4

probabilityis10%.

Theaveragedelayforsendingthescheduling request is 2 5 msUEdelayestimated 4ms

eNodeBdelayestimated 4ms

Corenetwork 1ms

l d l h ll d

schedulingrequestis2.5ms

Schedulinggrant:4ms. UEprocessingdelay:4ms,

Totaldelaywithpreallocatedresources

13.6ms

Totaldelaywithscheduling 20.1ms

p g y ,

eNodeB processingdelay:4ms corenetworkdelay:1ms.



Endtoendroundtriptimeincludingschedulinglatency

25

LTEroundtriptime

20

Core

15eNB

UE

Uplinkschedulinggrant

Uplink scheduling request

5

10Uplinkschedulingrequest

Retransmissions

Bufferingtime

Transmissiontime

0

Delayvalue



LTERefarmingtoGSMSpectrum

LTEcouldbedeployedintheexistingGSMspectrumlike 900 MHz or 1800 MHzlike900MHzor1800MHz.

TheflexibleLTEbandwidthmakesrefarmingeasierth ith WCDMA b LTE t t ith 1 4thanwithWCDMAbecauseLTEcanstartwith1.4MHzor3.0MHzbandwidthsandthengrowlaterh th GSM t ffi h d dwhentheGSMtraffichasdecreased.



LTErefarmingtoGSMspectrum Example



DimensioningCapacity Trafficvolumebasedapproach

Thebusyhourisassumedtocarry15%ofthedailytraffic

h b h l d thebusyhouraverageloadingis50%. Thecalculationshowsthatthetotal

sitethroughputpermonthis4600GB.

Tooffer5GBdataforeverysubscriberpermonth,thenumberofsubscriberspersitewillbe920.



DimensioningCapacity Dataratebasedapproach

Target:1Mbpspersubscriber. Sinceonlysomeofthe

subscribersaredownloadingdatasimultaneously,wecanapplyanoverbookingfactor,forexampleg , p20.

Itmeansthattheaveragebusyhour data rate is 50 kbps perhourdatarateis50kbpspersubscriber.

Thenumberofsubscriberspersiteusingthisapproachis1050.



Thanks for your AttentionThanks foryour Attention



LTE Technology Perofrmance Evaluation

ANNEXESLTETechnology Perofrmance Evaluation



ULlinkbudgetparametersforLTE Parameters1

R f LTE f UMTS OFDMA d SC FDMA B d R di A


Ref. LTE for UMTS OFDMA and SC-FDMA Based Radio Access Harri Holma and Antti Toskala


DLlinkbudgetparametersforLTE Parameters1





DLlinkbudgetparametersforLTE Parameters2




Documents

LTE Link Budget