utra system

8/6/2019 UTRA System

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THEUTRASYSTEM:THEUTRASYSTEM:PHYSICALLAYERPHYSICALLAYER

SPECITICATIONSSPECITICATIONS

Elect.AndComput.Engr.Dept.

Calif.StateUniv.,LosAngeles

FredDaneshgaran

DipartimentodiElettronica

PolitecnicodiTorino- Torino(Italy)

MarinaMONDIN

2

COURSETOPICSCOURSETOPICS

DS-CDMAandTD-CDMAtechnologiesbasicprinciples

Currentradiospecificationsof: FDD(W-CDMA)component

TDD(TD-CDMA)component


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DSDS--CDMACDMA

TECHNOLOGYBASICTECHNOLOGYBASIC

PRINCIPLESPRINCIPLES

4

ACCESSACCESS

Bythistermwemeanthewayinwhichtheradioresourceisaccessedandshared,withthegoalofmaximizingthenumberofservicedusersandminimizingtherequired

bandwithandpower.

DEFINITIONDEFINITION


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DUPLEXINGDUPLEXING

Inwirelesssystemstheuserisgenerallyallowedtosendinformationtothebase-stationandsimultaneouslyreceiveinformationfromthebase-stationitself.Inconventionaltelephonesystemsitispossibletotalkandlistenatthesametime:thiseffectisduplexing,andcanbeobtained

witheitherfrequencyortimebasedtechniques.

6

FREQUENCYDIVISIONDUPLEXING(FDD)FREQUENCYDIVISIONDUPLEXING(FDD)

TheFDDschemeisbasedontheuseoftwodifferentfrequencybandsforeachuser,oneforthebase-station-to-mobiletraffic(forwardlink),oneforthemobile-to-base-stationtraffic(reverselink)

Eachduplex channeliscomposedoftwosimplex channelsandaphysicaldevicenamedduplexer isrequiredinsideeachfixedandmobiletranceiverinordertoallowsimultaneoustransmissionandreceptiononthetwoduplexchannels

Inordertobeabletoutilizealow-costRFtechnology,forwardandreverselinkbandwithsshouldbeseparated.


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TIMEDIVISIONDUPLEXING(TDD)TIMEDIVISIONDUPLEXING(TDD)

TheTDDschemeusestimeinsteadoffrequencytoallowbothforwardandreverselinkcommunication

Ifthetimeseparationbetweentemporal slotsallocatedtoforwardandreverselinksissmall,transmissionandreceptionofdataappearsimultaneoustotheusers

TDDallowscommunicationusingasinglechannelandsimplifiestheradiodevicessincenoduplexerisrequired

8

MSBSTRANSMISSION

GUARDTIMES

Samecarrierforbothlinks

TDDTDD

(TIMEDIVISIONDUPLEX)(TIMEDIVISIONDUPLEX)

RFfilteringsimplified

Timeseparationbetweenlinkscannotbeguaranteedincellularsystemsduetopropagationdelaysinmacrocells

Usedincordlesssystems(e.g.,CT2,DECT)whichutilizemicrocellsorpicocell

BSMSTRANSMISSION

FRAMEPERIOD


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THEDSTHEDS--CDMATECHNIQUECDMATECHNIQUE

DS-CDMA(DirectSequence-CodeDivisionMultipleAccess):codedivisionaccesstechnique

Theusersignalsaretransmittedsimultaneouslyandonthesamefrequencyband

Adifferent(andunique)codeassignedtoeachuserallowsonetodistinguishthereceivedsignals

Thesystemcapacityislimitedbytheinterferencegeneratedbytheotherusers

10

DSDS--CDMACDMA

Theinformationbitismultipliedbyasequenceof0sand1scorrespondingtothecodeworduniquelyassociatedtotheuser

Atthereceivertheusefulinformationisrecoverdbymeansofacorrelationoperation

+1

-1

-1

-1

+1

+1

T t

t

t

PNi (f)

Di (f)

Si (f)

f

Ti

PNi (f)

Di (f)

Si (f)

f

f

Bs

Bs

Bss


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DSDS--CDMA(II)CDMA(II)

RECEIVERINPUTSIGNALRECEIVERINPUTSIGNAL

fBs

Bss

INTERFERINGSIGNAL

SSSIGNALNo

SIGNALAFTERDESPREADINGSIGNALAFTERDESPREADING

INTERFERINGSIGNAL

USEFULSIGNAL

f

No

Bs

Bss

Thede-spreadingoperationdistributesthepowerofanarrow-bandinterferingsignalontheentirechannelbandwidthBss,reducingtheinterferingpowerspectraldensityinthebandwidthBsoccupiedbytheusefulsignal

Thewhitenoisepowerspectraldensityisnot

affectedbythede-spreadingoperation,sincewhitenoiseisnotbandlimited

12

CDMACDMA

Signalsaretransmittedoveralltheavailablebandwidthforallthetime.Theresultisthatalltheusersinterferewitheachother,buttheuniquecodeassignedtoeachuserensuresthecorrectrecoveryofinformationatthereceiver

Theuserdata(forinstancetheoutputofthevoicecoder)aregeneratedwithacertainbit-rate,theneachbitismultipliedbythecodeworduniquelyassociatedtoeachnetworkuser

If,forinstance,a64bitcodewordisused,thetransmitterwillsendthiscodewordeachtimethatthevoicecodergeneratesa1,anditscomplementeachtimethatthevoicecodergeneratesa0


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CDMA(II)CDMA(II)

Inthisscheme,foreachusefulbitgeneratedbythevoicecoder,64bitsaresentonthechannel,thereforethebandwidthoccupiedbytheCDMAschemeis64timeslargerthanthebandwidthrequiredbytheFDMAscheme

Theratemeasuredintermsofchannelbits(i.e.thechannelbit-rate)iscalledchiprate

Themultiplicationbytheusercodewordiscalledspreading,whilethecorrelationprocessexecutedatthereciverto

recovertheusefulinformationiscalledde-spreading

14

THETRANSMITTERTHETRANSMITTER

Amplitude

Amplitude

Amplitude

CodeA

Time

Time

Time

Usercode

Informationsequence

Transmittedsequence

xx


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THERECEIVERTHERECEIVER

UserAInformationsequence

Codedsequence

UserBInformationsequence

CodedsequenceCodeA X Y

1

8

=

8

i=1

Xi Yi

Amplitude

TimeTime

ReceiverforuserAIdealchannel

Averageontheusefulbitperiod

Receivedsignal

Recoveredinformationsequence

Time

Time

X

X

16

DSDS--CDMACDMA

b(t):binaryinformationsignal(RateRb)c(t):binaryPNsequence(RateRc)

Rc>>RbThespectrumexpansionisduetothemultiplicationoftheusefulsignalbythePseudo-Noise(PN)signal

BPSKMOD.

BPSKDEMOD.

b(t)

c(t)

x(t)

j(t)

z(t)

c(t)

~~

fo


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DSDS--CDMA(II)CDMA(II)

c(t)1

-1

t

b(t)1t

-1

c(t)b(t)

1

-1

t

Gc(f)

f

1/Tc

f1/Tb

Gb

(f)

Gc*Gb

f

1/Tc

productspectrum

18

DSDS--CDMA(III)CDMA(III)

Thesignalb(t)c(t)ismodulated,transmitted,alteredbynarrow-bandinterferingsignalj(t)andthendemodulated,obtaining:

Therecoveredsignalisobtainedbymultiplyingz(t)byc(t):

z(t)=b(t)c(t)+j(t)~

Spreadedinterferingsignal

z(t)c(t)=b(t)c2(t)+j(t)c(t)=b(t)+j(t)c(t)~ ~


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DSDS--CDMA(IV)CDMA(IV)

Spectrumofz(t)c(t)

f

f

Gz(f)

f

Spreadedinterferingsignal

Usefulsignal

Usefulsignal

Interferingsignal

Afterfilteringonlyafractionoftheinterferingsignalisleft,withpowerreducedbyafactorG=Rc/Rb (spreadinggain)

20

CDMATRANSMISSIONCDMATRANSMISSION

DATA

0 f0 0

BACKGROUNDNOISE

f0

EXTERNALINTERFERENCE

f0

OTHERCELLINTERFERENCE

f0

OTHERUSERINTERFERENCE

f0

ENCODING&INTERLEAVINGDATA

CARRIER

PNSOURCE

CARRIER

DIGITALFILTER

PNSOURCE

CORRELATOR

DEINTERLEAVING&DECODING

DATA

WIDEBANDSPECTRUM

f0


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SPREADINGCODESFORCDMASPREADINGCODESFORCDMA

InanisolatedCDMAcell(withoutinterferingcells)eachuserusesadifferentspreadingcode(codewordorsequence)

Thespreadingsequencesshouldbeorthogonalinordernottogenerateinterference

Twocodewordsareorthogonaliftheirscalarproductonthesequencelength(multiplicationandadditionoftheresultingterms)isequaltozero

Example:thesequences1,-1,1,-1,1,-1,1,-1and1,1,-1,-1,1,1,-1,1areorthogonal

22

SPREADINGCODESFORCDMA(II)SPREADINGCODESFORCDMA(II)

TheprevioussequencesbelongtothefamilyoftheWalshcodes,whichareallorthogonaltoeachother

InanisolatedcellitispossibletoassignaWalshsequenceto eachuserinordertomaximizecapacity(whichislimitedbythenumberofavailablesequences,dependentonthesequencelength)

Inasystemwithmanycells,alltheusersinthedifferentcellsshouldhavedifferentsequences,sincealsoadjacentcellsare

usingthesamefrequencyband,butthiswouldstronglylimitthesystemcapacity


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Ifshortsequencesareused:itiseasiertocontrolinterference,butthecodemanagementismorecomplex

Ifonlyonebutverylongsequenceisused:codemanagementiseasybutitismoredifficulttocontrolinterference

LONGCODEANDSHORTCODELONGCODEANDSHORTCODE

24

THEFAMILYOFWALSHCODESOFLENGTH8THEFAMILYOFWALSHCODESOFLENGTH8

Code0 1

1

1

1

1

1

1

1

1

-1

-1

-1

1

1

-1

-1

-1

1

1

1

-1

1

1

-1

1

-1

-1

1

-1

1

1

-1

-1

-1

1

-1

1

-1

1

-1

1

1

1

-1

1

1

-1

-1

Code1

Code2

Code3

Code4

Code5

Code6

Code7

-1 -1 1 1 -1 -1 1 1

-1 1 -1 1 1 -1 1 -1


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SPREADINGCODESFORCDMA(III)SPREADINGCODESFORCDMA(III)

Inmulti-cellCDMAsystems,quasi-orthogonalcodesareused,thatallowmaintainingtheinterferenceamongdifferentusersatadmissiblelevels,evenifthislevelislargerthanintheorthogonalsequencescase

Thefamilyofquasi-orthogonalcodesiscomposedoftheso-calledpseudo-noiseorPNsequences

PNsequencesrepeatthemselvesperiodically:iftheyaremultipliedbythemselvesandadded,theresultisequaltothesequencelength(likefortheWalshcodes),whileiftheyare

multipliedbyashiftofthemselvesandaddedtheresultis-1(insteadof0,thereforesomeinterferenceisgenerated).TheadvantageisthatPNsequencesarepracticallyunlimited

26

PSEUDOPSEUDO--NOISESEQUENCESNOISESEQUENCES

Theyaretypicallyobtainedbyshiftsoffeed-backregistersproperlyinitialized,orbytheircombinations(GOLDsequencesareobtainedbycombiningtheoutputsoftwodifferentregisters)

IftheregisterhasNstages,thePNsequenceperiodis2N-1

IfPNsequenceshaveauto-correlationfunctionR(t)alwayszeroexceptfort=0andnullcross-correlationfunctions,thenitispossibletodistinguishthedifferentusersignals

Output

0 0 1


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t t

n

x1

f

t

f

t

+

1ej1

nejn

x

PROPAGATIONCHANNELEFFECTSPROPAGATIONCHANNELEFFECTS

28

RECEIVER:RAKERECEIVERRECEIVER:RAKERECEIVER

X

i

i

je i

X

n

n

je n

propagationchannelspreadingsequence

de-spreading

channelestimation

de-spreading

channelestimation

receiver

i

n

phaserecovery

phaserecovery


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POWERCONTROLANDINTERLEAVINGPOWERCONTROLANDINTERLEAVING

INCASEOFFASTFADINGINCASEOFFASTFADING

GOODGOOD

GOODGOODBADBAD

BADBAD

FadingSLOW

(Lowspeed)

FadingFAST

(Highspeed)

PowerControl

Coding&

interleaving

t

t

30

POWERCONTROL(PC)POWERCONTROL(PC)Closedlooppowercontrol- uplink(UL)anddownlink(DL)

Adjuststhetransmittedpowerfromthemobileterminal(fromthenetwork)inordertomaintaintheSIR(SignaltoInterferenceRatio)inUL(DL)equaltoagiventargetSIR

Outerlooppowercontrol- ULandDL

AdjuststhetargetSIRvalueusedbytheclosedlooppowercontrolonthebasisofaconnectionqualityestimate

Openlooppowercontrol- onlyULinUMTS

AdjuststhepowertransmittedontherandomaccessburstonthebasisofthepathlossvalueandtheinterferencelevelevaluatedinUL


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CLOSEDCLOSED--LOOPPOWERCONTROLLOOPPOWERCONTROL

Returnchannel

W-CDMAtransmitter

Poweramplifier

Receivedcommand(up/down)

BSCchannel FIFOregister

Roundtripdelay(kslot)Errorsonthecommand(Pe)

Receivingfilter

Rakereceiver

Max./Min.Transmittedpower W-CDMAreceiver

W-CDMAtransmitter

C

Cref

Transmittedcommand(up/down)

Comparator

+

-

32

GAINDUETOTHECLOSEDLOOPGAINDUETOTHECLOSEDLOOPPOWERCONTROLPOWERCONTROL

-2

-1

0

1

2

3

4

5

6

7

8

9

0 50 100 150 200 250 300

mobilespeed[km/h]

Eb/Noga

in[dB]

Mobilechannelvoiceserviceat8kbps

CONSTRAINTS:thetransmittermusthaveasufficientdynamictobeabletofollowthechannel;itneedsamarginattheedgesofthecoverage

area.Ifthedynamicisinsufficient,thegaintendstozero.


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EXAMPLEOFPROBABILITYDENSITYFUNCTIONSEXAMPLEOFPROBABILITYDENSITYFUNCTIONSOFTRANSMITTEDANDRECEIVEDPOWERSOFTRANSMITTEDANDRECEIVEDPOWERS

OutdoortoindoorpedestrianA

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

-20 -15 -10 -5 0 5 10 15 20

Power[dB]

Prob

.densityfunction

P.d.f.transmittedpower

P.d.f.receivedpower

34

CoreNetwork

RNC RNC

SiteContr

BTS BTS BTS

SiteContr

BTS BTS BTS

SiteContr

BTS BTS BTS

SiteContr

BTS BTS BTS

RNS

UTRAN

RNS

Iub

Iub

Iub

Iub

Iur

Iu

Iu

UTRANARCHITECTUREUTRANARCHITECTURE


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HANDHAND--OVER:SOFTHOOVER:SOFTHODEDICATEDDATACHANNELDEDICATEDDATACHANNEL

RNCRNC

MSreceivesfrombothBTSthesameinformationatthesametime

BTS1BTS1

BTS2BTS2

LC=X

LC=Y

LC=LongCode

36

HANDHAND--OVER:SOFTERHOOVER:SOFTERHODEDICATEDDATACHANNEL,DEDICATEDPACKETCHANNELDEDICATEDDATACHANNEL,DEDICATEDPACKETCHANNEL

RNCRNC

MSreceivesfrombothsectors

thesameinformationatthesametime

LC=X

Sector1Sector1

Sector2Sector2

BTSBTS

LC=Y

LC=LongCode


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SOFTHANDSOFTHAND--OVERANDMACRODIVERSITYOVERANDMACRODIVERSITY

CELLA CELLB

CELLC

Signalmargin

SoftHand-overregion

ADDthreshold

DROPthreshold

Timemargin

Ec/No

time

38

TYPESOFHANDTYPESOFHAND--OVEROVER

GSM

SIST TYPE

HardHardHandHand--overover

BEFORE DURING AFTER

DECT

SeamlessSeamlessHandHand--overover

UMTS

SoftSoftHandHand--overover

MSC

RNC

F1

BS#1

RFP#1

CCFP

BSS#1

F2

F2

BS#2

RFP#2

BSS#2BSS#2

MSC

F1

BS#2

RNC

F1BS#1

BSS#1BSS#2

MSC

F1

BS#2

RNC

F1

BS#1

RFP#1 RFP#2

CCFP

F1

BSS#1

RFP#2

CCFP

F2

RFP#1

F1


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SITESELECTIONDIVERSITYSITESELECTIONDIVERSITY

Itisanoptionalvariantoftheusualsofthand-over/macrodiversityscheme

Themobileidentifiesaprimarycellandsomenonprimarycellswithinitsactiveset

Withthegoalofreducingtheinterferenceduetothesofthand-over,thedownlinkinformationistransmittedonlybytheprimarycell

40

CAPACITY:ISOLATEDCELL,IDEALPCCAPACITY:ISOLATEDCELL,IDEALPC

Eb

Io

CT

I/W

C/R

I/W==

C=usefulsignalpower

R=bitrate

W=spreadingbandwidth

Incaseofidealpowercontrol

I=C(N-1)

1

(N-1)=

Eb

Io

C/R

C(N-1)/W= .

W

R

1

Eb/Io= .

W

R(N-1)


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EXPLOITATIONOFTHESOURCEEXPLOITATIONOFTHESOURCE

ACTIVITYANDSECTORINGACTIVITYANDSECTORING

d:sourceactivityfactor(forvoice,inidealconditions,itisequalto0.38,inpractice0.5istypicallyassumed)

Gsect:sectoringgain(2.2-2.4inthethreesectorscase)

1

Eb/Io .

W

RN

1

d. . Gsect Sitecapacity

42

CAPACITYINTHEMULTICAPACITYINTHEMULTI

--CELLCASECELLCASE

Theinter-cellinterferenceisaccountedforbymeansofaproperfactorgenerallydenotedasforianddefinedas:

f=(interferencefromothercells)/(intracellinterference)

1

Eb/Io .

W

RN

1

d. . Gsect. 1/(1+f)

f,variesaccordingtothescenario(typicalvaluesare0.4-0.6);thefactorf(alsodenotedasi),issometimescalledthereusefactoroftheCDMAsystem


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NOTESONTERMINOLOGYANDHYPOTHESISNOTESONTERMINOLOGYANDHYPOTHESIS

N0 isoftenusetoindicatetheoverallinterferencepowerspectraldensity(realinterferenceplusthermalnoise)insteadofthemoreappropriateexpression(I0+N0)

Itisimportanttopayattentiontothepointwithinthetransmissionchainwherewearemakingourcalculations:theprocessinggainshouldalwaysbeevaluatedatthepointinwhichtheratioEb/(I0+N0)isknown

Inthecapacitycomparison,attentionshouldbegiventowhetherwearetalkingaboutfulltimeusersornot,andifthecapacity

valuesarereferredtoasectorortoasite

44

CELLDYNAMICSCELLDYNAMICS

C/I 1/N

CellofradiusRwithNusers

Theuserdensityincreases:CellwithradiusRwith(N+X)>>>> Nusers

(C/I) 1/(N+X)


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CELLBREATHINGCELLBREATHING

UMTS:voiceserviceat8kbit/sinurbanenvironment(fc=2GHz)

Constraintsonthecoverageradius:mobilemaximumpower(21dBm),BaseTransceiverStation(BTS)maximumpower,maximumsourcebitrate,systemmargins

andload(maximum78activeusers,Equivalentof1)

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0 0.2 0.4 0.6 0.8 1

load

radius[km]

46

COVERAGERADIUSCOVERAGERADIUS

2Mbit/s

144kbit/s

13kbit/s

Thecellcoverageradiusdependsonthetypeofofferedservice

Asaconsequence,adifferentcellularplanningmustbedesignedand

foreseendependingonthetypeofofferedservices


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COVERAGERADIUSCOVERAGERADIUS

Thecoverageradiusislimitedbythemaximumpowerthatcanbetransmittedbythemobileuser

Itispossibletoofferserviceswithasymmetrictransmissionratesonthetwolinks(b-mandm-b)withlargecoverageradius

Thebasestationhaslessconstraintsonthemaximumtransmittedpower:

asaconsequence,itispossibletoguaranteealargecoverageradiusofferingforinstanceonly8kbit/sinuplinkand144kbit/sindownlink

inthisway,itispossibletoguaranteeapplicationssuchaswebbrowsing,inwhichthemobileterminalmakessomerequestsorsendsacknowledgementwhilereceivingalargeamountofdata

48

POWERTRANSMITTEDBYTHEBASEPOWERTRANSMITTEDBYTHEBASE--STATIONSTATION

30

32

34

36

38

40

42

0 0.2 0.4 0.6 0.8 1

load

PowerBTS[dBm]

MaximumpowertransmittedbytheBTSintheworstcase(usersonthecellborder)- loadof1=78activeusers

Duetothecellbreathingphenomenon,themaximumpowertransmittedbythebasestationdoesnotincreaselinearlywiththenumberofusers


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LINKPERFORMANCELINKPERFORMANCE

50

Channeldecoding

Channelcoding

sourcepuncturing

unequalinterleaver

modulation

spreading

filter

BER

channel

AWGN

CRC&tail

insertionor

repetition

&TX

Fading

filterRX

demodulation

de-spreading&de-interleaverCRC&tail

removal

counter de-puncturing

repetitionorremoval

Powercontrolcommand

DPCCH

generator

MUX

DEMUX

DPCCH

DPDCH

DPCCH

DPDCH

WW--CDMADOWNLINKRADIOCHAINCDMADOWNLINKRADIOCHAIN


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6

7

8

9

10

11

12

13

14

15

16

17

1 10 100 1000

velocitdelmobile(km/h)

Eb/No[dB]@

BER=0

.1%

OutdoortoindoorA

OutdoortoindoorB

VehicularA

VehicularB

W-CDMA:VOICESERVICE(8KBIT/S)

DOWNLINKWORKINGPOINT

52

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

4 4.5 5 5.5 6 6.5 7 7.5

Eb/No[dB]

BER

it.#1

it.#2

it.#3

it.#4

it.#5

it.#6

it.#7

it.#8

TPCHard

TPCSoftBLER

PerformanceofthedataserviceLCDat144kbit/swithTurboCodeasafunctionofthenumberofdecodingiterations

downlink(VehicularA- 120km/h)


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Channeldecoding

Channelcoding

sourcepuncturing

unequalinterleaver modulation

spreading

filter

BER

channel

AWGN

CRC&tail

insertionor

repetition&

TX

Fading

filterRX

Demodulation

De-spreading&

Combining

&

de-interleaverCRC&tail

removal

counter de-puncturing

repetitionor

removal

Powercontrolcommand

DPCCH

generator

DPCCH

DPDCH

DPCCH

DPDCH

channel

AWGN

Fading

filterRX

WW--CDMAUPLINKRADIOCHAINCDMAUPLINKRADIOCHAIN

54

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

0 1 2 3 4

E b/N o[ dB ]

BER

it.#1

it.#2

it.#3

it.#4

it.#5

it.#6

it.#7

it.#8

TPCHard

TPCSoft

BLER

PerformanceofthedataserviceLCDat144kbit/swithTurboCodeasafunctionofthenumberofdecodingiterations

uplink(VehicularA- 120km/h)


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CONSIDERATIONSCONSIDERATIONS

Inthecaseofvoiceservicestheperformancesarepracticallyindependentofthespeed (withintherange25250km/h)becauseoftheclosedlooppowercontrol.Thisbehaviourisnotexactlytrueanymoreforhighbitrateservices

Forveryhighspeeds (500km/h)theperformancesareaffectedbya56dBdegradationbecausethechannelestimationalgorithmandthepowercontrolarelessreliable

56

BASICPRINCIPLESOFTHEBASICPRINCIPLESOFTHE

TDTD--CDMATECHNIQUECDMATECHNIQUE


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TDDCOMPONENT(TDTDDCOMPONENT(TD--CDMA)CDMA)

Freq

uenc

y

8TCHpertime

slot

OneTimeSlot

3.84

MHz

1 2 3 . . . 14 15

Codes1-16

Energy

Time

framewith15timeslots

WB-TDMA/CDMA

58

USERCODESUSERCODES

Withineach0.667msslot,afurtherseparationisgivenviatheuseofcodewords withlength16

Severalburstscanbetransmittedinasingletimeslot:

theburstscanbeallocatedtodifferentusers,

and/ortheburstscanbeallocatedtoasingleuser

Themostcriticallinkistheuplink,whereuptoeightburstscanbetransmittedinasingletimeslot(with

moreburststheperformanceswouldbeexcessivelydegraded)


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RESOURCESALLOCATIONRESOURCESALLOCATION

IntheTDDcomponent,aphysicalchannelischaracterisedbyacombinationofcarrierfrequency,slotandcodeword

ResourcesareallocatedbymeansofslowDCA:

inordertoobtainaunitaryreuseparameter,differenttimeslotsareallocatedtoadjacentcells(slotclustering)

eachcellslotcanbeusedinuporindownlink(forasymmetrictraffic)

ResourcesareallocatedtothebearersbymeansoffastDCA:

thehigherbitrateservicescanbeobtainedbytransmittingusingmultiplecodewordsandmultipletimeslots

60

THETDDFRAMETHETDDFRAME

Problem:mobile-mobileinterference

canbesolvedbyforcingthebasestationssynchronism

inanasynchronousnetwork,itisnecessarytohaveadynamicresourceallocationpolicyinordertoavoidinterference(likeintheDECTcase);thiswillcauseanefficiencylossinthebandlimitedcase(5

MHz) Timingadvancetechniquesareemployedinorderto

reducetheguardtimesbetweentwosuccessiveslots


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SYNCHRONIZATIONAMONGTDDCELLSSYNCHRONIZATIONAMONGTDDCELLSCellA

Cell B

Withsynchronouscells,timingadvanceandguardtimesitispossibletoavoidthemobiletomobileinterference

Mobiletomobileinterference

Withnonsynchronizedcells,inordertoavoidmobiletomobileinterference,resourcesneedtobeallocatedforthecasesofpotentialconflict

62

BASICFUNCTIONINGPRINCIPLEBASICFUNCTIONINGPRINCIPLE

CDMAcode1

Midamblechannel1

Trafficchannel1inputdata

Mobile1

1

ChannelestimationofK

radiochannels

JointDetection(JD)ofK

trafficchannels

1 K2

TrafficchannelK

outputdata

Trafficchannel1outputdata

Radiochannels Estimatedradio

channels1- K

Basestation

Midambleschannels1- K

CDMAcodes1- KK

CDMAcodeK

MidamblechannelK

TrafficchannelKinputdata

MobileK

X

X


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63

THEJOINTDETECTIONTECHNIQUETHEJOINTDETECTIONTECHNIQUE

Itisusedtoreduce(ideallytocancel)interferenceamongdifferentsignals

Thereceiver,exploitingtheknowledgeofthesequencesusedtodistinguishthedifferentusersignals,jointlydemodulatesthedifferentsignals

Theoutputisaseriesofinformationsequences,oneforeachusersignal

64

THEUMTSSYSTEMRADIOTHEUMTSSYSTEMRADIO

INTERFACEINTERFACE


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65

ETSIDECISIONSETSIDECISIONS

AdoptionoftheW-CDMAsolutionwithFDDduplexinginthepairedportionoftheavailablespectrum

AdoptionoftheTD-CDMAsolutionwithTDDduplexinginthenon-pairedportionoftheavailablespectrum

Parametersoptimization inordertoguarantee: low-costterminals

smoothevolutionwithrespecttoGSM

dualmodeTDD/FDDterminals

Thesolutionmustbeabletooperatewithaminimumspectrum

assignmentequalto2x5MHz(FDD)

66

HARMONIZATIONWITHHARMONIZATIONWITHCDMA2000CDMA2000

Agreementamongthemajoroperators

Threeoperatingmodes:

FDDDS(basedonUTRANWCDMA)

FDDMC(basedoncdma2000,withpossibilityofoverlaywithcdmaOnenetworks)

TDD(basedonUTRANTD-CDMA)

PossibilityofconnectiontoGSMMAPandANSI41core

networks


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67

HARMONIZATIONWITHHARMONIZATIONWITHCDMA2000CDMA2000(II)(II)

Chiprate:3.84McpsforDSandTDD,3.6864(3x1.2288)McpsforMC

AdoptionofacommonpilotchanneltransmittedinCDMAfortheDSsolution

Possibilityofbothsynchronousorasynchronousnetworks.

68

POSSIBILITYOFOPERATIONINAPOSSIBILITYOFOPERATIONINA

2X5MHZBANDWIDTH2X5MHZBANDWIDTH

Thisrequirementimposesconstraintsontheout-of-bandemissions

SinceboththeTDDandtheFDDcomponentsoccupythesamebandwidth,theyhavesimilarrequirementsasfarasguardbandsandadjacentchannelprotectionisconcerned

Employedmethods: Evaluationoftheminimumcouplingloss(minimumdistance

amongtransmitterandreceiver)abletoguaranteethereceiver

operation(worstcasecondition). Statisticalapproach(Montecarlosimulation)toevaluatethe

capacitylossduetothedifferentmulti-operatorscenarios

Problem:isitpossibletooperateTDDintheFDDband?


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69

UTRA/FDD UTRA/TDD

Multipleaccess WCDMA HybridWCDMA+TDMA

Chiprate

Carrierspacing 4.4-5MHz(200kHzcarrierraster)

3.84Mcps(SFFDD:4-256,TDD1-16)

Frameduration 10ms

N.ofslotsperframe 15

BTSsynchronisationNotnecessary Notnecessary

butpreferable

Modulation DL:QPSK

UL:Dual-codeBPSK UL:QPSKCoherentreception uplinkanddownlink

Multi-rate VariableSF+Multi-code+Multi-slot(onlyTDD)

THEMAINPARAMETERSTHEMAINPARAMETERS

DL:QPSK

70

FDDCOMPONENT(WFDDCOMPONENT(W--CDMA)CDMA)

TheFDDcomponentisbasedonthesystemdevelopedbytheAlphagroupandestablishestheadoptionofawide-bandCDMAaccesstechnique:

chiprateof3840kchip/s(theywere4096beforetheharmonisationwithcdma2000)

3dBbandwidthequalto3840kHz(raisedcosinefilter,roll-off0.22)

optionwithchiprateof2x3840and4x3840kchip/s

Coverageofpico-,micro- andmacro-cellsobtainedbyadoptingdifferentCDMAcarriersinthedifferentenvironments:

hierarchicalcoveragebasedontheFDMAaccess

Inacertainhierarchicallevelitispossibletohaveafrequencyreusefactorequalto1


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73

DPxCHCHANNELSFRAMESTRUCTUREDPxCHCHANNELSFRAMESTRUCTURE

Frame:has10msofdurationAframeisformedby15slots(0.666ms),correspondingtoapowercontrolperiod

Spreadingfactor:belongingtothe

range4-256,canbedifferentforDPDCHandDPCCH

DataNdatabits

0.666ms,10x2k

bits(k=0..6)

Tf =10ms

DPDCH

DPCCH

Slot#iSlot#1 Slot#2 Slot#15

PilotN

pilot bitsTPC

NTPC bitsFBI

NFBIbitsTFCI

N TFCI bits

74

MAPPINGBETWEENTHEMAINTRANSPORTMAPPINGBETWEENTHEMAINTRANSPORTANDPHYSICALCHANNELSANDPHYSICALCHANNELS-- DOWNLINKDOWNLINK

Physicalchannels: DPDCHandDPCCHaretransmittedlikeintheuplinkbuttime-multiplexed

DSCH(downlinkSharedChannel)isusedtotransmitpackettrafficscheduledbythebasestationaccordingtothetrafficgenerated bythevarioususers.Italwayshasanassociateddedicatedchannelusedtotransportphysicallevelsignalling(forinstancepowercontrolandinformationratebits)

BCHisthecommonchannelusedtotransmitsysteminformationto allmobiles;itistransmittedonthePrimaryCommonControlPhysicalChannel(PCCPCH).TheSynchronisationChannel(SCH)istime-multiplexedwithit,anditallowsthemobiletoacquirethesynchronisationsignalnecessarytodemodulatethebasestationsignal

SCCPCH(SecondaryCommonControlPhysicalChannel)isusedtotransmitthepagingandtheFACHchannelwhich,togetherwiththeAICH,areusedtoindicatethatthecallgeneratedbythemobilecanstart.Thesechannelscanalsobeusedtotransmitshortpackets(likeSMSin GSM)


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75

PHYSICALCHANNELS:DOWNLINKPHYSICALCHANNELS:DOWNLINK

DPCCHandDPDCHaredefinedasintheuplink,buttheyaretimemultiplexed

Thededicatedpilotsymbolsaretransmittedalsointhedownlinkinordertosupportthe

useofsmartantennas

Slot#1 Slot#2 Slot#i

Tf =10ms

0.666ms,20x2k

bits(k=0..6)

Slot#15

TPCN TPC bits

Data2N data2 bits

DPDCH

PilotN

pilotbits

DPCCHDPDCH DPCCH DPCCH

TFCITFCIN bits

Data1Ndata1 bits

76

COMMONCONTROLCHANNELS(CCPCH)COMMONCONTROLCHANNELS(CCPCH)TheCCPCHchannelsare:primary - usedtotransporttheBCCH(systemandcellspecificinformation);theyaretransmittedonallthecell;secondary - usedtotransporttheFACH(mobilespecificcontrolinformationandshortpackets)andthepagingchannelPCH.

Theprimarychannelspeedisconstant,thatofthesecondarychannelscanvaryfromcelltocell

Thecommonpilotchannel(CPICH)isusedforchannelestimationontheprimaryCCPCHandtoimprovethechannelestimationonthededicatedchannels

Slot#1 Slot#2 Slot#i

Tf =10ms

0.666ms,20x2k

bits(k=0..6)

Slot#15

Data19 bits

(TxOFF)

256chips

CPICH20bits


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77

MULTIPLEXINGOFMULTIPLEXINGOFTHETRANSPORTTHETRANSPORT

CHANNELSCHANNELSRate-Matching

Multiplexing

2nd Interleaving

MappingtoPhysicalchannels

AddCRCtoTr.block

AddCRCto

Tr.block

Channelcoding

Channelcoding

TrCH TrCH

1st Interleaving 1st Interleaving

78

CODINGTECHNIQUESCODINGTECHNIQUES

Channelinterleaving

BER=10-3

Service-specificcoding

BER=10-6 Channelinterleaving

Convolutionalcoding

Turbocoding


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79

MAPPINGOFTHEMAPPINGOFTHE

UPLINKVOICEUPLINKVOICE

SERVICESSERVICES

80bits

i nformati on CRC tai l

8 8

96x3=288bits

convolutionalencoding

288x24/25=300bits

unequalrepetition

spreading

Slot#1 Slot#15

in-phasecomponentDPDCH(SF=128)

quadraturecomponentDPCCH(SF=256)

frame(10ms)

1536chips6bits

5122

5122

1536chips6bits

5122

5122

Pilot TPC TFCI

2560chips20bits

2560chips20bits

300x128=38400chips

80

i nformati on CRC tai l

80bits 8 8

96x3=288bits

convolutionalencoding

288x25/16=450bits

unequalrepetition

450x128=57600chips

spreading

512chip4bits

1281

1920chip15bits

Slot#1 Slot#15

Pil ot T PC DataDPCCH+DPDCH(SF=128)

in-phasecomponent

quadraturecomponent

frame(10ms)

MAPPINGOFMAPPINGOF

THEDOWNTHEDOWN

LINKVOICELINKVOICE

SERVICESSERVICES

512chips4bits

1281

1920chip15bits

512chip4bits

1281

1920chips15bits

512chips4bits

1281

1920chips15bits


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83

SPREADINGANDMODULATIONSPREADINGANDMODULATION-- UPLINKUPLINK

Channelisationcodes(OVSF)

cD,cC :channelisationcodesc scramb:scramblingcode(shortorlong)p(t):pulse-shapingfilter(rootraisedcosine,roll-off0.22)

EachmobiletransmitsatleasttheDPCCH,towhichauniquechannelisationcodeisassigned;toeachDPDCHachannelisationcode

isassigned Thesamecodecanbereusedonin-phase&quadraturecomponents Thescramblingcodeisacomplexsequence QPSKmodulationisused

DPDCH

cD

I

DPCCH

cC

Qj

I+jQ

cscramb

cos(t)

p(t)

p(t)

Real

Imag

sin(t)

84

SPREADINGANDMODULATIONSPREADINGANDMODULATION-- DOWNLINKDOWNLINK

Thesamechannelisationcodemultipliesatthesametimethein-phaseandquadraturecomponents Thescramblingcodeisarealsequencethatmultipliesboth

components QPSKmodulationisused

cch:channelisationcodesc scramb:scramblingcodep(t):pulse-shapingfilter(rootraisedcosine,roll-off0.22)

cos(t)

DPDCH/DPCCH

I

Q

p(t)

p(t)

cscrambS P cch sin(t)


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85

OPENLOOPPOWERCONTROLOPENLOOPPOWERCONTROL

IsusedtoestimatetherequiredpowerfortheaccessburstonthePRACH

ThemobilemeasuresthereceivedpoweronthecommonpilotchannelandevaluatestheattenuationonthedownlinkonthebasisofthepowerusedtotransmittheprimaryCCPCH(valuetransmittedontheBCH)

IftheinterferenceontheuplinkandtheSIRtargetareknown(valuestransmittedontheBCH),themobileestimatesthepowertobetransmittedonthePRACHunderthehypothesisofidenticalattenuationontheuplinkandanddownlink

86

ULCLOSEDLOOPPOWERCONTROLULCLOSEDLOOPPOWERCONTROL

ThebasesoftheactivesetestimatetheusefulpowerreceivedontheDPCCHinuplink,thetotalinterferenceandthecurrentvalueofSIRinuplink

ThebasegeneratesTPCcommandsandsendthemtothemobiletocommandanincrease(TPC=0)ordecrease(TPC=1)ofthetransmittedpower

ThemobilecombinesmultiplereceivedTPCcommandsintoauniqueTPCcommand

Themobileincreasesordecreasesbyapredefinedstepitstransmitpower


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87

DLCLOSEDLOOPPOWERCONTROLDLCLOSEDLOOPPOWERCONTROL

ThemobileterminalestimatestheusefulreceivedpowerindownlinkontheDPCH,thetotalreceivedinterferenceandthecurrentvalueofSIRindownlinkrelativetotheconnection

ThemobileterminalgeneratesaTPCcommandandsendsittothenetwork(nodeB)

Thenetworkadjuststhetransmittedpowervaryingitby

apredefinedstep

88

UPLINKVARIABLERATE(NODTX)UPLINKVARIABLERATE(NODTX)

1-rate

10ms

Variablerate

1/2-rate

1/4-rate

0-rate

:DPCCH(Pilot+TPC+RI)

:DPDCH(Data)

R=1 R=1/2 R=0 R=0 R=1/2


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89

DOWNLINKVARIABLERATE(DTXBASED)DOWNLINKVARIABLERATE(DTXBASED)

1-rate

1/2-rate

1/4-rate

0-rate

0.625ms

:DPCCH-part(Pilot+TPC+RI)

:DPDCH-part(Data)

90

INTERINTER--FREQUENCYMEASUREMENTSFREQUENCYMEASUREMENTS

TDMA:Discontinuoustransmission

RXRXdownlink

TX TXuplink

IdletimeforIFmeasurements

RXdownlink

TXUplink

UTRA/FDD:Normallycontinuoustransmission


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91

DOWNLINKSLOTTEDTRANSMISSIONDOWNLINKSLOTTEDTRANSMISSION

Tf =10ms IdletimeforIFmeasurements

SF=SF0

SF=SF0/2

SF=SF0

92

HANDHAND--OVERWITHINATDDSCHEMEOVERWITHINATDDSCHEME

BothTDDandFDDcomponentshave10msframeduration

ThebasestationmustindicatetheTDDandFDDcarriersusedinthearea

TheFDDmodecanuseslottedtransmission(ortworeceivers)inordertoexecutetherequiredmeasurements:

theFDDterminalsmustsynchroniseitselfwiththeTDDdownlink

sincetheTDDcellsinacertainareaaresynchronous,itissufficienttoobtaintheup/downlinktiminginonecelltobesynchronisedontheentirearea

sincethefrequencyseparationbetweenTDDandFDDcannotbesufficienttoprotecttheTDDreceiverfromtheinterference

generatedbytheFDDcomponent,itcanbenecessarytointerrupttheFDDtransmissionduringmeasurements:thisisthesocalledslottedmodeinuplink

TheTDDterminalscanexploittheidleperiodstoexecutemeasurementsontheFDDcomponent


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93

PACKETACCESSPACKETACCESS

Therearethreepossibleschemes:

shortpackets(ornotfrequent)transmittedovercommonchannels(PRACHandSCCPCH),similartoSMSintheGSMcase

largedimensionpacketsorpacketsscheduledathighrate,thatcanbetransmittedusingadedicatedchannel

indownlinkitispossibletouseacommonchannel(PDSCH)onwhichthebasestationschedulesthe

accessofpacketsbelongingtodifferentclients.InuplinkthePCPCH(contestchannel)canbeused

94

COMMONCHANNELPACKETACCESSCOMMONCHANNELPACKETACCESS

Nolinkmaintenancewhennopackettotransmit

Limitedtosmallpacketsandmediumdatarates

Accessrequest

Userpacket

Accessrequest

Userpacket

Arbitrarytime

CommonChannel(RACH/FACH)


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95

DEDICATEDCHANNELMULTIDEDICATEDCHANNELMULTI--PACKETPACKET

TRANSMISSIONTRANSMISSION

Scheduledandnon-scheduledpacketaccess

Closed-looppowercontrolduringpackettransmission Linkreleasedaftertime-outperiodhasexpired

Userpacket

Userpacket

DedicatedChannel(DTCH)

Accessrequest

Userpacket

Accessrequest

Linkmaintenance(pilot,TPC)

Scheduledpackets

Non-scheduledpacket

96

DSCHANDCPCHCHANNELSDSCHANDCPCHCHANNELS

DSCHisachannel(downlink)commontoalltheuserswhichtransportscontrolanddedicatedtrafficbits

CPCHisachannel(uplink)thatcanbeaccessedbymanyusersthroughacontestmechanism,used

forresourceoptimization inpackettransmission


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97

ETSIDECISIONETSIDECISION

Parametersoptimization inordertoguarantee:

low-costterminals

dualmodeTDD/FDDterminals

98

FDDANDTDDPARAMETERSHARMONIZATIONFDDANDTDDPARAMETERSHARMONIZATION InordertosatisfytheETSISMGrequirements,ithasbeen

decidedtoharmonisetheTDDandFDDcomponentsparameters:

chiprate:3840kchip/s

frameduration:10ms

numberofslotsperframe:15

modulation:QPSK

filtering:raisedcosine(roll-off0.22)

unitaryfrequencyreuse

Thespecificationsareharmonised,i.e.theyhavethesame

structure:manypartsarepracticallyidenticalforthetwomodes(codingtechnique,multiplexingofthetransportchannels,andsoforth)

Somedifferencesstillexistbecauseofthedifferentaccesstechnique


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99

THETDDFRAMETHETDDFRAME

3.84Mchip/s

time

frequency

666s

10ms

10ms

10ms

Examplesofswitchingmodesbetweenupanddownlink:theswitchinginstantsmustbethesameforallthecellsinacertainarea

100

RADIORESOURCESRADIORESOURCES

Aphysicalchannelisdefinedbythefollowingparameters:

frequency

timeslot

channelisationcode

burstformat

frameallocation(i.e.,transmissiononalltheframesoronlyduringcertainframes,forinstanceonlyontheevenframes)

Ineachframeitismandatorytoallocateatleastonetimeslotfordownlinkandonetimeslotforuplink


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101

SPREADINGSPREADING

Theinformationsequencesaremultipliedwithachannelisationcode(thatcausesthebandwidthincrease)andtheresultingsignalismultipliedbyascramblingsequence

Indownlink,thespreadingfactorassumesthefixedvalueSF=16;inordertoprovidehighsymbolrateservices,morethanonechannelisationcodepertimeslotisassigned

TheoptionSF=1isalsopossible

Inuplinkthespreadingfactorcanassumevaluesinthe

range1-16 Amobilecansimoultaneouslytransmitnotmorethan

twophysicalchannelsinthesametimeslot

102

SIGNALLINGCHANNELSSIGNALLINGCHANNELS

TheprimarycommoncontrolchanneltransportstheinformationassociatedwiththeBCHanditistransmitted:

withknownpower

overallthecell(nobeamforming)

inknownposition(i.e.,timeslotnumber,burstformatandcodeareknown)ontheSCH,usingSF=16andtype1bursts

ifotherchannelsaretransmittedonthesameslotwiththesamecode(indifferentframesinamultiframepattern),thesehavethesamecharacteristicsasPCCPCH:knownreferencepowerandandnobeamforming

Thesynchronisationchannel(SCH)istransmittedovereachframe(oneortwoslotsperframe)

itallowsthemobiletoacquiresynchronisation

itisusedforpowermeasuresfortheuplinkpowercontrol


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103

BURSTFORMAT:THETRAFFICBURSTBURSTFORMAT:THETRAFFICBURST

Therearetwotypesoftrafficbursts:thefirsttypehasalongermidambleandisparticularlysuitedto

uplinkinthecaseofchannelswithlargedelayspreads;thesecondtypecanbeusedinchannelswithlowdelayspreadsBothcanalsobeusedtotransmittheS-CCPCH

Datasymbols61(976chips)

Midamble512chips


GP96CP

666s


Midamble256chips

666s


GP96CP

104

PHYSICALLEVELSIGNALLINGPHYSICALLEVELSIGNALLING

Thephysicallevelsignallingistime- multiplexedwiththetrafficchannel

Theonlymandatoryfieldisthemidamble(usedforchannelestimationandjointdetection)

Datasymbols Midamble DatasymbolsGP

512/256chips

2560*Tc

TPC

TFCI


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105

PHYSICALLEVELSIGNALLING(II)PHYSICALLEVELSIGNALLING(II)

Whenmorethanonecodeisused,themidamblepowerisequaltothesumofthetrafficchannelpowers

TheTFCIbitsaretransmittedonlyonthefirstcode/timeslot

t

Code

2560*Tc

Data

Midamble

TFCI

t

2560*Tc

Data

Midamble

TFCI

utra system

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