dual transfer mode in umts

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DualTransferModeDualTransferModeDualTransferModeDualTransferMode

DateDateDateDate:::: 10.03.2009

Revision:Revision:Revision:Revision: 005/DTM/009

Author:Author:Author:Author: JakubBluszcz

Leliwa Technical Bulletin

Copyright2010L

eliwa.

AllR

ightsR

eserved.


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LeliwaTechnicalBulletinDualTransferMode

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TableofcontentsTableofcontentsTableofcontentsTableofcontents

TopicTopicTopicTopic PagePagePagePage

Introduction.....................................................................................................3GPRSsignallingoverDCCH...........................................................................5 Singleslotoperation .......................................................................................7DTMcapabilities .............................................................................................8

Layer1modifications......................................................................................9Signallingprocedures ...................................................................................11AcronymsandAbbreviations ........................................................................18References ...................................................................................................20Disclaimer.....................................................................................................21


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DualTransferModeLeliwaTechnicalBulletin

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IntroductionIntroductionIntroductionIntroduction

ThedefinitionofGPRSclassAmodeofoperationinRelease97assumesatotalindependencebetweentheCSandPSdomains.Thusthedirect

implementationoftheexistentstandardsforclassAwouldresultinmobile

stationsthatarerequiredtooperateintwodifferentfrequencieseitherinthe

sametimeslot,intimeslotsnandn+3ortheiradjacentones.This

complicatesenormouslytheinternalarchitectureoftheMS,resultingina

veryhighdevelopmentcost,whichbothoperatorsandmanufacturerswould

prefertoavoid.

Nevertheless,operatorshaveexpressedtheirneedforthistypeofmobiles,

sincetheywanttoofferservicesthatdemandthesimultaneousexistenceofa

CSconnectionandaPSsession.Thisisparticularlyimportantduringthe

coexistenceofGSM/GPRSwithUMTS,asthesecapabilitieswillexistin

UMTS.However,UMTScoveragemaynotbeavailableinsomeareaswhere

thereisGSM/GPRScoverage(e.g.deepinsidebuildingsorwhenroamingto

a2Gnetwork).Ascoverageisavitalservice,inorderforanoperatortobe

abletosellUMTSclassAservicesitisnecessarytobeabletoimitateclass

AservicesinareasofonlyGSMcoverage.Ontheotherhand,theprovision

ofclassAserviceswithGERANtechnologyisalsoessentialforoperators

withoutUMTScoverage.

TheDTMsolutionovercomestherestrictionsmentionedaboveandmakes

possibletohavesimultaneousCSandPSactiveconnections.Thisis

achievedbysendingPSdata(signallinganduserdata)onthetimeslotusedbytheCSconnectionorothertimeslot(s)thatinbothdirectionsare

contiguouswiththetimeslotusedbytheCSconnection,seeFig.12-1.

Forpaging,thebehaviouroftheMSisasinclassBmodeofoperation.

TheDTMappliestherestrictionthattheMSisnotrequiredtooperateintwo

differentfrequenciesinthesamemomentintime.However,GSMCSand

GSMGPRSservicesarestillsupportedsimultaneously.Thus,theDTM

featureisasubsetoftheGPRSclassAcapabilities.

Rx

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 75 6 7

Tx

f1

f1

CSPS measurements

Figure1MultislotconfigurationofasimpleclassAMSinDTM


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TheAinterfaceismodifiedsothattheBSCknowstheIMSIassociatedwith

eachSCCPconnectiontotheMSC.ThismeansthattheBSCisableto

ensurethatpacketpagingmessagescanbedeliveredtoMSswhichhavea

connectiontotheMSC.ThesamefunctionalitycanbereusedtodeliverMSC

originatedpagestomobilesinpackettransfermodewhilethenetworkisinmodeofoperationII(i.e.noGsinterface).

SGSN

MSC

BSS

SCCP COIMSI

Paging-PS(P-TMSI, IMSI)

SGSN

MSC

BSS

IMSI

Paging Cmd.(TMSI, IMSI)

Figure2Pagingcoordination(noGsinterface)

MobilitymanagementinDTMisbasicallythesameasforclassAmobiles

(i.e.BSSdecidesabouthandoverforCSandthePShastofollowtheCS

connection).InordertomaketheMSawareofRAchangesduringtheDTM

modetheSystemInformation,type6isextendedtocontaintheRoutingArea

Code.

CS

RA #2

RA #1

SACCH(RA

C#2)

SACCH

(RAC#1)

MSC

SGSN

RAupdate

Figure3SystemInformation,type6(RACparameter)


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Inter-BSChandoverisplannedtobecontrolledbyAinterfacesignalling.The

oldBSStonewBSSinformationelementisusedtoindicatetothetarget

BSCthattheMSisinDTM.

BSC

MSC

BSC

CS

Handoverrequired(DTMinformation)

Handoverrequest(DTMinformation)

Figure4InterBSCHOduringDTM

DTMdefinitionDTMdefinitionDTMdefinitionDTMdefinition

AnMSinDualTransferMode(DTM)hasresourcesforanRRconnection

andissimultaneouslyallocatedresourcesforoneormoreTBFs,provided

thattheBSSco-ordinatesitsallocationofradioresources.DTMisoptionalbothfortheMSandthenetwork.ADTMmobileisaclassAmobile.

GPRSsignallingoGPRSsignallingoGPRSsignallingoGPRSsignallingoverDCCHverDCCHverDCCHverDCCH

IfGPRSsignallingneedstobesentduringavoicecall,thentheseLLC

framesaresentonthemainDCCH(FACCHorSDCCH)withLayer2SAPI

0.ThisusesanewProtocolDiscriminatorinSignallingLayer3message

structureforLLC:GTTP(GPRSTransparentTransportProtocol).

BSSmain DCCH

GPRS Transparent Transport Protocol (GTTP)

GPRS signalling

Figure5GTTPGPRSTransparentTransportProtocol


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TheuseofthemainDCCHisonlyallowedwhentheMSisindedicated

mode.InDTM(i.e.theMShasresourcesallocatedforanRRconnectionand

foroneormoreTBFs),themainDCCHcannotbeusedandthecurrent

GPRSresourcesareusedforthetransferofGPRSsignalling.

GPRSuserdatacannotbesentonthemainDCCH.

RestrictionsRestrictionsRestrictionsRestrictions

TheuseofthemainDCCHforGPRSsignallingissubjecttocertain

restrictionstoreducetheharmtothespeechquality.

ThenumberofLAPDmframeshastobesmallerthanacertainvalue

specifiedbythenetwork(parameterMAX_LAPDm)inmessageDTM

InformationsendonthemainDCCH.Whentheparameterdefiningthe

maximumnumberofLAPDmframeshasnotbeenreceivedbytheMSintheservingcell(e.g.immediatelyafterahandover),theMSassumesthedefault

valuedefinedequalto5LAPDmframes.

Ifthemessageislongerthatthespecifiedlimit,theMSrequestsanuplink

TBF.

MSMSMSMS----SGSNtunnellingSGSNtunnellingSGSNtunnellingSGSNtunnelling

TheGPRSinformationfromupperlayers(i.e.GMMorSM)isalwayssent

insideanLLCframe.ThisLLCframecannowbepasseddown:

toRLCandtransmittedonaTBF;or

toRR,iftheMSisindedicatedmode,andtransmittedonthemainDCCH.

ThenewtunnellingmechanismforthetransmissionoftheLLCframeis

showngraphicallyinFig.12-6.

L1

Network

Service

GSM RF

L2

RR/GTTP BSSGP

L1

LLC

GMM/SM

Network

Service

BSSGP

L1

LLC

GMM/SM

L2

RR/GTTP

Message Message

LLC PDU LLC PDU

LLC PDU

GTTP PDU BSSGP PDU

L2 L2

SGSNBSSMS

Figure6TransmissionofanLLPDUonthemainDCCH


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Intheuplink,theLLCPDUisinsertedinanewLayer3message,withanew

ProtocolDiscriminator(GTTP)sothattheBSCidentifiesthetunnelling

mechanismwithouttheneedtoanalysetheMessageType.ThisLayer3

messageissenttotheBSConthemainDCCH,withtheexistingLayer2

mechanisms.TheBTSre-assembliestheLayer3messageandsendsittotheBSC.TheBSCextractstheTLLIandtheLLCPDU,whicharethenput

intoaBSSGPUL-UNITDATA.

Inthedownlink,whentheBSSreceivesadownlinkBSSGPPDU,itcan

identify:

ifthePDUcontainssignallinginformation(TbitintheQoSprofile);

ifthelengthoftheLLCPDUmeetstherequirements;and

ifithasanRRconnectiontotheaddressedMS(withtheIMSI);

inwhichcase,itsendstheLLCusingthesameprocedureasdescribed

above.Ifanyoftheconditionsaboveisnotmet,theBSCsendsthe

informationonadownlinkTBF.

SingleslotoperationSingleslotoperationSingleslotoperationSingleslotoperation

IftheMSinDTMhasoneTSallocatedfortheCSservices,itispossibletoreusethesameTSforthetransmissionofGPRSsignallinganduserdata.userdata.userdata.userdata.In

suchcasetheCSinformationandRLC/MACblocksaremultiplexedinthe

sameTSoftheTDMAframe.

TheconfigurationoflogicalchannelsusedinthatcaseiscalledTCH/H+

PDCH/H,whichmeansthatononephysicalchannelnetworkconfiguresone

CShalfrateconnectionandPSconnectionusestheremaininghalfofthe

physicalchannel.

Thisconfigurationisveryusefulwhenitisimpossibleforthenetworkto

allocateaTBFinsomecircumstancesonseparateTS(e.g.congestedcell,

multislotcapabilitiesnotsupportedintheservingcell).

Onthe'TCH/H'part,thesupportofAMRasthespeechcodecismandatory.

ThePDCH/Hisaresourcededicateddedicateddedicateddedicated(allocatedexclusively)totheMSinboth

directionsandcannotbesharedwithotherGPRSMS.Forinstance,ifan

uplinkTBFisestablished,thenetworkmaysendacontrolmessageinanyof

thedownlinkblocks.Nodownlinkdata,however,aresentwithoutaprevious

downlinkassignment.

Intheuplink,theMStransmitsinanyoftheblocksofthePDCH/H,

irrespectiveoftheUSFinthepreviousblocks.


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PDCH/H

TCH/H

(exclusive allocation)

Figure7Singleslotoperation

MuMuMuMultislotoperationltislotoperationltislotoperationltislotoperation

Inmultislotoperation,theGPRSdataissentonaPDCH.Thenumberof

timeslotscomprisingthePDCHisdecidedbythenetworkaftertakingintoaccountthemultislotcapabilitiessupportedbytheMS.

ThePDCH/FmaybesharedwithotherGPRSMS.

PDCH

TCH

(dynamic allocation)

Figure8Multislotoperation

DTMcapabilitiesDTMcapabilitiesDTMcapabilitiesDTMcapabilities

MSDTMcapabilitiesMSDTMcapabilitiesMSDTMcapabilitiesMSDTMcapabilitiesTheMSDTMclassisindicatedintheClassmark3andMSRadioAccess

Capabilities.TheabsenceofthisinformationindicatesthattheMSdoesnot

supportsimpleclassA(i.e.eitheritsupportsunrestrictedclassAoritcannot

operateinmodeofoperationAatall).ThesupportofenhancedCS

establishmentandreleaseisindicatedintheMSClassmark3andMSRadio

AccessCapabilityinformationelements.


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MSDTMclassesMSDTMclassesMSDTMclassesMSDTMclasses

DifferentMSssupportsdifferentDTMcapabilitiesandthustheyneedtobe

communicatedtothenetworksothattheycanbetakenintoaccountforthe

allocationofradioresources.TheDTMmultislotcapabilitiesareindependentfromthepreviouslydefinedmultislotcapabilities(i.e.HSCSDmultislotclass,

ECSDmultislotclass,GPRSmultislotclass,EGPRSMultiSlotClass)

WhenEGPRSissupported,DTMmultislotcapabilityforEGPRSoperationis

indicatedindependentlyfromDTMmultislotcapabilityforGPRSoperation.

UptonowDTMmultislotclasses5,6,9,10and11aredefined,otherclasses

canbedefinedinthefutureifstrictlyrequired,seeappendixA,Fig.A-5.

UseoffullandhalfrateUseoffullandhalfrateUseoffullandhalfrateUseoffullandhalfrate

Themixoffullandhalfratepacketdatachannelsisnotallowedintheuplink.

ThismixisonlydefinedforthedownlinkdirectionandonlysupportedbyMSs

indicatingsupportforExtendedGPRSDTMMultiSlotClassorExtended

EGPRSDTMMultiSlotClassrespectively.Thehalfratepacketdatachannel

isonlyallowedonthesametimeslotasthecircuitswitchedchannel.

NetworkDTMNetworkDTMNetworkDTMNetworkDTMccccapabilitiesapabilitiesapabilitiesapabilities

ThenetworkindicatesontheBCCHorPBCCHwhetherornotthecell

supportsDTMandifsowhetherornotitsupportsenhancedCS

establishmentandrelease(describedlater).

ItalsoindicatesitontheSACCHforDTMcapableMSsindedicatedmodeor

dualtransfermode.ItmayalsoindicateitonthePACCHforDTMcapable

MSsinpackettransfermode.Acelllevelindicationisneededbecause

adjacentBTSsmaybeinthesameRAandLAbutmaybeparentedby

differentBSCs(fromdifferentvendorsordifferentreleases).Theindicationin

theSACCHisneededtoenable/suppressthetransmissionofpacket

resourcerequestswhentheMSisindedicatedmodeandcannotreadthe

BCCHdata.

Layer1modLayer1modLayer1modLayer1modificationsificationsificationsifications

TimingadvanceTimingadvanceTimingadvanceTimingadvance

AMSinDTMdisablesthetimingadvancefeaturesfortheGPRSside(i.e.:

theMSinhibitsthetransmissionoftimingadvanceaccessburstsandignores


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thereceptionofGPRStimingadvancemessages.ThecontroloftheTA

valueisdoneovertheSACCH.

MeasurementreportingMeasurementreportingMeasurementreportingMeasurementreporting

TheMScontinuestosendmeasurementreportsfortheCSpart,butGPRS

measurementreportsarenotsent.


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SignallingproceduresSignallingproceduresSignallingproceduresSignallingproceduresTheexistentestablishmentproceduresforclassAmodeofoperationrelyon

thecapabilityoftheMStobeabletooperateindifferentfrequenciesinthe

sametimeslot,e.g.tolistentothe(P)BCCHwhileindedicatedmode.New

proceduresareaddedtothespecificationstoallowMSswithoutsuch

capabilitiestobeabletoentertheDTM.

PSPSPSPSestablishmentwhileindedicatedmodeestablishmentwhileindedicatedmodeestablishmentwhileindedicatedmodeestablishmentwhileindedicatedmode

AnewmessageisdefinedtoenabletheMStorequesttoentertheDTM:the

DTMRequestDTMRequestDTMRequestDTMRequestmessage.

TwoDTMassignmentDTMassignmentDTMassignmentDTMassignmentmessagesaredefined:

DTMAssignmentCommandDTMAssignmentCommandDTMAssignmentCommandDTMAssignmentCommand:thismessagedescribesboththeCSand

packetresourceswhenareallocationoftheCSresourceisneeded,

e.g.whenamultislotconfigurationcannotbeaccommodatedorwhen

an"TCH/H+PDCH/H"configurationistobeused.

PacketAssignmentPacketAssignmentPacketAssignmentPacketAssignment:thismessagedescribestheallocatedpacket

resourceswhennoreallocationoftheCSresourceisnecessary,e.g.onanadjacentTS.

DTM Assignment Command Packet Assignment

C0

C1

C2

C0

C1

C2

C0

C1

C2

C0

C1

C2

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

Figure9DTMassignmentmessages


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WhenthereisreallocationoftheCStimeslot:

iftheMSsuccessfullyestablishesthenewCSconnection,itsendsan

AssignmentCompleteAssignmentCompleteAssignmentCompleteAssignmentCompletemessageonthenewmainDCCH.

iftheMSfailstoestablishthenewCSconnection,itgoesbacktotheoldtimeslot,sendanAssignmentFailureAssignmentFailureAssignmentFailureAssignmentFailuremessageontheoldmain

DCCHandcontinuetheCSoperation.TheMSassumesthattheold

PSresourceswerereleasedandattemptitsre-establishment.

IfthenetworkwantstomovetheMStoanothercell,itsendsaHandoverHandoverHandoverHandover

CommandCommandCommandCommandmessageonthemainDCCH.Afterthehandoverprocedureis

completedandiftheMSwasinDTMintheoldcell,thenetworksendsthe

DTMInformationDTMInformationDTMInformationDTMInformationmessageonthemainDCCHtospeedupresumptionofthe

DTMoperationbytheMS.

MOsessionMOsessionMOsessionMOsession

IftheservingcelloftheCSconnectionindicatesthatsupportsDTM,theMS

requeststheestablishmentofaPSsessionbysendingaDTMRequesDTMRequesDTMRequesDTMRequestttt

messageonthemainDCCH.

ThenetworkanswerstherequestwithoneofthetwodefinedDTM

assignmentmessages,sentonthemainDCCH.Ifthenetworkcannot

allocatethepacketresources,itshallanswerwithaDTMRejectDTMRejectDTMRejectDTMRejectmessageon

themainDCCH.TheDTMRejectmessageindicatesifthemobileisallowed

toreattemptthepacketestablishmentinthesamecell(possiblyaftera

waitingtime).

Fig.12-10showsthesuccessfulcaseoftheallocationofanuplinkTBFwhen

thereallocationoftheCStimeslotisneeded.TheMSinformsthenetwork

aboutthecorrectseizureofthenewCSresourcebysendinganAssignment

CompletemessageonthemainDCCHofthenewresource.

BSC

DTM Request

Assignment Complete

DTM Assignment Command

RLC block(s)

MSC SGSN

CS dedicated mode

UL-Unitdata

old DCCH

old DCCH

new DCCH

uplink TBF

Figure10MOPSsessionestablishmentwhileindedicatedmodewith

reallocationoftheCSresource


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InFig.12-11,thepacketresourceismappedontoadjacenttimeslot(s)and

thusthePacketAssignmentmessageisused.Thereisnoreleaseand

re-establishmentofthemainsignallinglink.

BSC

DTM Request

Packet Assignment

RLC block(s)

MSC SGSN

CS dedicated mode

UL-Unitdata

old DCCH

old DCCH

uplink TBF

Figure11MOPSsessionestablishmentinmultislotconfigurationwhileindedicatedmode

MTsessionMTsessionMTsessionMTsession

ReadystateReadystateReadystateReadystate

IftheMSisintheReadystate,theSGSNsendsanLLCframetotheBSS

parentingtheMS'sservingcell.ThedownlinkLLCPDUincludestheIMSIifit

isknown.AstheIMSIoftheMSwaspreviouslystored,theBSSisableto

identifythattheMStowhichthedataissentisindedicatedmode.TheBSSBSSBSSBSSusesthemainsignallinglinkusesthemainsignallinglinkusesthemainsignallinglinkusesthemainsignallinglinktosendthedownlinkassignmentcommand

insteadofthe(P)CCCH,becauseaMSindedicatedmodedoesnotlistento

the(P)CCCHunlessitisunrestrictedclassAcapable.

TheassignmentisdonewithoneoftheDTMassignmentmessages,senton

themainDCCH.

Fig.12-12showsthesuccessfulcase,whenadownlinkTBFisassigned

withoutreallocationoftheCSresource.

BSC

Packet Assignment

RLC block(s)

MSC SGSN

CS dedicated mode

DL-Unitdataold DCCH

downlink TBF

Figure12MTPSsessionestablishmentwhileindedicatedmode,packetidle

modeandReadystate


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Standbystate:packetnotificationStandbystate:packetnotificationStandbystate:packetnotificationStandbystate:packetnotification

IftheMSisintheStand-bystateandtheSGSNhassomethingtosend,it

sendsapagetotheBSS(s)parentingtheRAwheretheMSis,inordertofind

outtheactualservingcell/BVCI.AstheMShasanestablishedsignallingconnectionwiththeBSS,theBSSdoesnotpagetheMS.Instead,theBSS

informstheMSthatitisbeingpagedforpacketservices.Thisisdoneby

sendingthePacketNotificationPacketNotificationPacketNotificationPacketNotificationmessageonthemainDCCH.TheMS

answersthenotificationwithaCellUpdateprocedure:sendinganLLCframe

toactasaPacketPagingResponse.

Forthatpurpose,theGMMlayerrequeststheestablishmentofuplink

resources.IftheLLCframeisdummy(i.e.doesnotconveyuserdata

information)anditisshortenough,theMSsendsitonthemainDCCH.

Otherwise,anuplinkTBFisneededanditsestablishmentisdone.

OncetheLLCframeissent,theMSmovestotheGMMReadystate.TheSGSNunderstandstheLLCframeasavalidpageresponseandstarts

sendingthedownlinkinformation.Inordertoforwardthisinformationtothe

MS,theBSSsendasecondassignmentmessageassoonasitreceivesthe

datafromtheSGSN.

BSC

Paging PSPacket Notification

RLC block(s)

MSC SGSN

CS dedicated mode

DTM Request

Packet Assignment

LLC frame

DL-UnitdataPacket Assignment

Figure13MTPSsessionestablishmentwhileindedicatedmodeand

Standbystate(generalcase)

CSestablishmentwhileinpackettransfermodeCSestablishmentwhileinpackettransfermodeCSestablishmentwhileinpackettransfermodeCSestablishmentwhileinpackettransfermode

Wheninpackettransfermode,eithertheMSorthenetworkmayinitiateaCS

connectionestablishment.Inbothcases,thepacketsessionmaybeaborted

andtheestablishmentoftheCSconnectionisinitiated.

WhentheestablishmentoftheCSconnectionisinitiatedbythenetwork,the

CSpagingmessagemaycomedirectlyfromtheMSCorviatheSGSNifthe

Gsinterfaceispresent.TheBSSisabletoverifyinbothcasesifthepaged

MSisinpackettransfermodeandifsosendstheCSpageonthePACCH.


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ThispagingcoThispagingcoThispagingcoThispagingco----ordinationcanbereusedforGPRSMSsinmodeofoperationordinationcanbereusedforGPRSMSsinmodeofoperationordinationcanbereusedforGPRSMSsinmodeofoperationordinationcanbereusedforGPRSMSsinmodeofoperation

B,sothattheMSdoesnotneedtolistentothePCH.ThisfeaturebreakstheB,sothattheMSdoesnotneedtolistentothePCH.ThisfeaturebreakstheB,sothattheMSdoesnotneedtolistentothePCH.ThisfeaturebreakstheB,sothattheMSdoesnotneedtolistentothePCH.Thisfeaturebreaksthe

linkbetweenthlinkbetweenthlinkbetweenthlinkbetweenthepresenceoftheGsinterfaceandthenetworkcapabilitytoepresenceoftheGsinterfaceandthenetworkcapabilitytoepresenceoftheGsinterfaceandthenetworkcapabilitytoepresenceoftheGsinterfaceandthenetworkcapabilityto

performpagingcoperformpagingcoperformpagingcoperformpagingco----ordination.ordination.ordination.ordination.

OnceontheDCCH,theMSrequeststhere-establishmentofthepacket

resourcesbysendingaDTMRequestmessageDTMRequestmessageDTMRequestmessageDTMRequestmessage.Theproceduretore-

establishanaborteduplinkTBFareidenticaltotheMOsessionrequest.The

proceduretore-establishanaborteddownlinkTBFisidenticaltotheMT

sessionrequest.

BSC

Paging

MSCSGSN

PS session in progress

BSSAP+ Paging RequestPaging CS PDUPacket Paging RequestMTonly

Abort PS sessionAbort PS session

Channel Request

Immediate Assignment

Dedicated mode (signalling mode)

Paging Rsp (MT) / CM Service Req (MO) SCCP Connection Request

SCCP Connection ConfirmClassmark Change

Classmark Update

Common ID (IMSI)DTM Request

DTM Assignment Command

Assignment Complete

PS session

Assignment RequestChannel Mode Modify

Channel Mode Modify Ack. Assignment Complete

Dedicated mode (speech + signalling)

Authentication, Security and Call Control Procedures

Figure14CSconnectionestablishmentwhileinpackettransfermode

UponreceivingtheAssignmentRequestmessagefromtheMSC,theBSS

maysendoneofthefollowingmessagestotheMS:

ChannelModeModifyChannelModeModifyChannelModeModifyChannelModeModifymessagetomodifytheexistingCSchannels

mode,asshowninFig.12-14,

DTMAssignmentCommandDTMAssignmentCommandDTMAssignmentCommandDTMAssignmentCommandmessagetoreallocatetheCSresourceandmaintainsomePSresources.

AsAsAsAssignmentCommandsignmentCommandsignmentCommandsignmentCommandmessagetoreallocatetheCSresourceand

dropthePSresources.

EnhancedCSestablishmentEnhancedCSestablishmentEnhancedCSestablishmentEnhancedCSestablishment

IftheIftheIftheIftheMSandthenetworksupportenhancedCSestablishmentaCSMSandthenetworksupportenhancedCSestablishmentaCSMSandthenetworksupportenhancedCSestablishmentaCSMSandthenetworksupportenhancedCSestablishmentaCS

connectionmaybeestablishedwhileinpackettransfermode,withoutreleaseconnectionmaybeestablishedwhileinpackettransfermode,withoutreleaseconnectionmaybeestablishedwhileinpackettransfermode,withoutreleaseconnectionmaybeestablishedwhileinpackettransfermode,withoutrelease

oftheoftheoftheofthepacketresources.packetresources.packetresources.packetresources.


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AnMSthatsupportsenhancedCSestablishmentdetermineswhetherornot

thenetworksupportsenhancedCSestablishmentbyreadingtheGPRSCell

Optionsincludedwithinsysteminformationmessages.

MobileMobileMobileMobile----originatedcaseoriginatedcaseoriginatedcaseoriginatedcase

Inthemobile-originatedcase,theMSrequestsaCSconnectionbysending

thePacketCSRequestPacketCSRequestPacketCSRequestPacketCSRequestmessageonPACCHtothenetwork.

TheMSisnotallowedtosendaPacketCSRequestifthecountdown

procedurehasbeenstartedontheuplinkTBFandtherearenodownlink

TBFsinprogress.Thisensuresthatthenetworkhastimetorespondwitha

CSassignmentbeforeallthePSresourcesaredropped.

BSC

Packet CS request

Assignment Complete

Packet CS command

MSCSGSN


PACCH

PACCH

main DCCH

CS dedicated mode

Figure15MSoriginatedRRconnectionrequestprocedure

UponreceiptofthePacketCSRequestPacketCSRequestPacketCSRequestPacketCSRequestmessage,thenetworkrepliestothe

MSwithaPacketCSCommandPacketCSCommandPacketCSCommandPacketCSCommandmessageonPACCHthatencapsulatesone

ofRRmessages:

DTMAssignmentCommandDTMAssignmentCommandDTMAssignmentCommandDTMAssignmentCommand

ThenetworkallocatesbothPSandCSresourcestotheMSbysending

an(RR)DTMAssignmentCommandmessage.WhentheMSreceives

thismessageitstartsCSconnectionestablishmentandentersDTM.ThenetworkmayalsoreallocatePSresourcesintheDTMAssignment

Commandmessage.Inthiscasetheresultingchannelcombinationmust

beTCH+PDTCH,SDCCH+PDTCHisnotallowed.

ByomittingthePSresourcedescriptionintheDTMAssignment

Command,thenetworkindicatesthatthecurrentPSresourcesare

maintained.

ImmediateAssignmentImmediateAssignmentImmediateAssignmentImmediateAssignment

ThenetworkallocatesonlyCSresourcestotheMSandordersthe

releaseofPSresourcesbysendingan(RR)ImmediateAssignment

message.WhentheMSreceivesthismessageitreleasesthePS


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connectionandestablishestheCSconnection.Whenindedicatedmode

theMSmayrequestPSresourcesbyproceduresdescribedearlier.

ImmediateAssignmentRejectImmediateAssignmentRejectImmediateAssignmentRejectImmediateAssignmentReject

ThenetworkrejectstheCSrequestbysendingan(RR)ImmediateAssignmentRejectmessage.WhentheMSreceivesthismessageit

continuesinpackettransfermodenormally.TheMSmaylaterreinitiate

theCSconnectionrequest.

IfthePSresourceshavebeendroppedbeforethenetworkhasachanceto

respondtothePacketCSRequest,thenetworkabortsthecurrentDTM

procedure.IftheMSdoesnotreceiveaPacketCSCommandmessageafter

ithassentacorrespondingPacketCSRequestmessage,theMSdropsany

PSresourcesandstartCSaccessproceduresontheRACH.

MobileMobileMobileMobile----terminatedcaseterminatedcaseterminatedcaseterminatedcase

Inthemobile-terminatedcasetheBSSsendstotheMSaPacketCS

CommandmessageonPACCHwhenreceivingaCSpagingmessagefrom

thecorenetwork.ThePacketCSCommandmessageencapsulatesoneof

(RR)DTMAssignmentCommandorImmediateAssignment.Theirmeaning

isthesameasforthemobile-originatingcase.

BSC

Assignment Complete

Packet CS command

MSCSGSN


PACCH

main DCCH

CS dedicated mode

(enhanced CS establishment)

Paging

Pag. Req.Paging CS

Figure16MSterminatedRRconnectionestablishment


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AcronymsandAbbreviationsAcronymsandAbbreviationsAcronymsandAbbreviationsAcronymsandAbbreviations

BSCBSCBSCBSC BaseStationControllerBSSBSSBSSBSS BaseStationSystemBSSGPBSSGPBSSGPBSSGP BaseStationSystemGPRSProtocol.BTSBTSBTSBTS BaseTransceiverStationCMCMCMCM ConnectionManagementCPICHCPICHCPICHCPICH CommonPilotChannelCSCSCSCS CircuitSwitching

CSCSCSCS ConvergenceSublayerDCCHDCCHDCCHDCCH DedicatedControlChannel(logicalchannel)DLDLDLDL DownlinkDTMDTMDTMDTM DualTransferModeEGPRSEGPRSEGPRSEGPRS EnhancedGPRSEHPLMNEHPLMNEHPLMNEHPLMN EquivalentHomePLMNEPLMNEPLMNEPLMNEPLMN EquivalentPublicLandMobileNetworkFACHFACHFACHFACH ForwardAccessChannel(transportchannel)FDDFDDFDDFDD FrequencyDivisionDuplexGERANGERANGERANGERAN GSM/EDGERadioAccessNetworkGPRSGPRSGPRSGPRS GeneralPacketRadioService

GSMGSMGSMGSM GlobalSystemforMobileCommunicationGTTPGTTPGTTPGTTP GPRSTransparentTransportProtocolHPLMNHPLMNHPLMNHPLMN HomePLMNIMSIIMSIIMSIIMSI InternationalMobileSubscriberIdentityLALALALA LocationAreaLACLACLACLAC LocationAreaCodeLAILAILAILAI LocationAreaIdentityLAPDLAPDLAPDLAPD LinkAccessProcedureforD-ChannelLLCLLCLLCLLC LogicalLinkConnectionMCCMCCMCCMCC MobileCountryCodeMEMEMEME MobileEquipment

MNCMNCMNCMNC MobileNetworkCodeMOMOMOMO MobileOriginatedMSMSMSMS MobileStationMSCMSCMSCMSC MobileServicesSwitchingCentrePDCHPDCHPDCHPDCH PacketDataChannelPDTCHPDTCHPDTCHPDTCH PacketDataTrafficChannelPDUPDUPDUPDU PacketDataUnitPLMNPLMNPLMNPLMN PublicLandMobileNetworkPSPSPSPS PacketSwitchingPSPSPSPS PresenceServicePPPP----TMSITMSITMSITMSI PacketTemporaryMobileSubscriberIdentityRARARARA RoutingArea


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RACRACRACRAC RoutingAreaCodeRLCRLCRLCRLC RadioLinkControlRLCRLCRLCRLC ReleaseCompleteMessageRSCPRSCPRSCPRSCP ReceivedSignalCodePower

SACCHSACCHSACCHSACCH SlowAssociatedControlChannelSCCPSCCPSCCPSCCP SignallingConnectionControlPartSDCCHSDCCHSDCCHSDCCH StandAloneDedicatedControlChannelSGSNSGSNSGSNSGSN ServingGPRSSupportNodeSIMSIMSIMSIM SubscriberIdentityModuleSMSMSMSM Session-basedMessagingSoLSASoLSASoLSASoLSA SupportofLocalisedServiceAreaTCHTCHTCHTCH TrafficChannelTMSITMSITMSITMSI TemporaryMobileSubscriberIdentityTSTSTSTS TimeSlotULULULUL UplinkUMTSUMTSUMTSUMTS UniversalMobileTelecommunicationSystemUSIMUSIMUSIMUSIM UMTSSubscriberIdentityModuleUTRANUTRANUTRANUTRAN UMTSTerrestrialRadioAccessnetworkVPLMNVPLMNVPLMNVPLMN VisitedPLMN


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ReferencesReferencesReferencesReferences

Thissectioncontainsthelocationsofvariousspecifications,document

referencesandusefulinformationwhereyoucanlearnmoreaboutthis

subject.

[1] 23.060GeneralPacketRadioService(GPRS);Servicedescription;

Stage2

[2] 43.064GeneralPacketRadioService(GPRS);OveralldescriptionoftheGPRSradiointerface;Stage2

[3] 44.018Mobileradiointerfacelayer3specification;RadioResource

Control(RRC)protocol

[4] 22.060GeneralPacketRadioService(GPRS);Servicedescription;

Stage1

[5] 45.002Multiplexingandmultipleaccessontheradiopath

[6] 43.055DualTransferMode(DTM);Stage2


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