SIST EN 300 948 V7.0.1:2003

• Abstract:

  Upgrade from Phase 2+ to Release 1998

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.070.50 - Global System for Mobile Communication (GSM)
• Technical Committee: SS EIT - Technical Board for the electrotechnical, information technology and telecommunications fields
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Dec-2003
• Due Date: 01-Dec-2003
• Completion Date: 01-Dec-2003
• Ref Project: ETSI EN 300 948 V7.0.1 (2000-01) - Digital cellular telecommunications system (Phase 2+) (GSM); Group Call Control (GCC) protocol (GSM 04.68 version 7.0.1 Release 1998)

Overview

SIST EN 300 948 V7.0.1:2003 outlines the Group Call Control (GCC) protocol for the digital cellular telecommunications system (GSM Phase 2+, Release 1998). Developed by the Slovenski inštitut za standardizacijo (SIST) in line with the European Telecommunications Standards Institute (ETSI), this standard specifies how group call sessions are managed over the radio interface, specifically to support the Voice Group Call Service (VGCS) within GSM networks. This upgrade moves GSM group call capabilities from Phase 2+ to Release 1998, reflecting enhancements and refinements in mobile telecommunications and critical communication services.

Key Topics

Group Call Control Protocol

• Purpose: The GCC protocol governs setup, management, and release of group calls in GSM systems, supporting services such as VGCS.
• Scope: Describes message flows, state management, and procedural interactions between mobile stations (MS) and the network.
• Peer Entities: Focuses on the two key protocol peers - the MS (usually used by the group call participant or originator) and the network side.

Control States and Elementary Procedures

• Mobile Station States: The GCC protocol defines several states (e.g., NULL, MM CONNECTION PENDING, GROUP CALL INITIATED, ACTIVE, PRESENT, CONNECTION REQUESTED, TERMINATION REQUESTED) guiding the behavior of mobile stations during group call sessions.
• Network States: States specific to network-side group call handling mirror mobile station states for synchronization and session continuity.
• Elementary Procedures:
  • Establishment (starting a group call)
  • Termination (ending a group call)
  • Information phase (status, parameter exchange)
  • Miscellaneous (timer handling, abnormal cases)

Message Handling

• Defines standardized messages such as CONNECT, SETUP, TERMINATION, STATUS, and GET STATUS for robust and interoperable group call communications.
• Includes detailed requirements for handling abnormal cases (e.g., unknown message types, transaction identifier errors, radio link failures).

Interoperability and Consistency

• Ensures that the GCC protocol is harmonized with related GSM protocols by referencing core GSM technical specifications (such as GSM 04.08, GSM 02.68, etc.).
• Details consistency checks, timer usage, and state transitions for reliable operation.

Applications

SIST EN 300 948 V7.0.1:2003 serves as a foundational document for:

• Public Safety and Emergency Communications: Supports efficient group communication for first responders and critical infrastructure operators where coordinated action is required.
• Railways and Transportation: Enables reliable group calls for train control, logistics, and operational teams.
• Enterprise Communication Solutions: Used in business environments requiring coordinated dispatch and instant communication capabilities.
• Network Equipment Manufacturers and Mobile Operators: Assists in developing, testing, and deploying devices and infrastructure compliant with GSM Release 1998 group call features.

Related Standards

• GSM 02.68: Voice Group Call Service (VGCS) service description
• GSM 03.68: VGCS Stage 2, including call flows and interactions
• GSM 04.08: Mobile radio interface layer 3 specification
• GSM 04.07: Signaling Layer 3 general aspects
• ETS EN 300 925, EN 300 927, EN 300 932, EN 300 933, EN 300 938, EN 300 939, EN 300 940: Covering aspects such as numbering, addressing, eMLPP, data link, and general CM sublayer management in GSM.

Summary

SIST EN 300 948 V7.0.1:2003 is essential for ensuring robust, secure, and interoperable group call services in GSM networks according to Release 1998. Compliance with this standard is vital for manufacturers, operators, and service providers seeking to deliver efficient and mission-critical mobile communication across a variety of sectors, especially where group call functionality is required.

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.NUPLOMHQMDDigital cellular telecommunications system (Phase 2+) (GSM); Group Call Control (GCC) protocol (GSM 04.68 version 7.0.1 Release 1998)33.070.50Globalni sistem za mobilno telekomunikacijo (GSM)Global System for Mobile Communication (GSM)ICS:Ta slovenski standard je istoveten z:EN 300 948 Version 7.0.1SIST EN 300 948 V7.0.1:2003en01-december-2003SIST EN 300 948 V7.0.1:2003SLOVENSKI
STANDARD
ETSIEN300948V7.0.1(2000-01)EuropeanStandard(Telecommunicationsseries)Digitalcellulartelecommunicationssystem(Phase2+);GroupCallControl(GCC)protocol(GSM04.68version7.0.1Release1998)GLOBALSYSTEMFORMOBILECOMMUNICATIONSRSIST EN 300 948 V7.0.1:2003

ETSIETSIEN300948V7.0.1(2000-01)2(GSM04.68version7.0.1Release1998)ReferenceREN/SMG-030468Q7KeywordsDigitalcellulartelecommunicationssystem,GlobalSystemforMobilecommunications(GSM)ETSIPostaladdressF-06921SophiaAntipolisCedex-FRANCEOfficeaddress650RoutedesLucioles-SophiaAntipolisValbonne-FRANCETel.:[phone]Fax:[phone]SiretN°34862356200017-NAF742CAssociationàbutnonlucratifenregistréeàlaSous-PréfecturedeGrasse(06)N°7803/[e-mail]ETSIdeliverablecanbedownloadedfromhttp://www.etsi.orgIfyoufinderrorsinthepresentdocument,sendyourcommentto:[e-mail]Ideliverablemaybemadeavailableinmorethanoneelectronicversionorinprint.Inanycaseofexistingorperceiveddifferenceincontentsbetweensuchversions,thereferenceversionisthePortableDocumentFormat(PDF).Incaseofdispute,thereferenceshallbetheprintingonETSIprintersofthePDFversionkeptonaspecificnetworkdrivewithinETSISecretariat.CopyrightNotificationNopartmaybereproducedexceptasauthorizedbywrittenpermission.Thecopyrightandtheforegoingrestrictionextendtoreproductioninallmedia.©EuropeanTelecommunicationsStandardsInstitute2000.Allrightsreserved.SIST EN 300 948 V7.0.1:2003

ETSI3ETSIEN300948V7.0.1(2000-01)(GSM04.68version7.0.1Release1998)ContentsIntellectualPropertyRights.5Foreword.51Scope.62References.63Definitionsandabbreviations.63.1Definitions.63.2Abbreviations.74Applicability.75Mainconcepts.76ElementaryproceduresforGroupCallControl.86.1Overview.86.1.1General.86.1.2Groupcallcontrolstates.106.1.2.1GroupcallcontrolstatesattheMSsideoftheinterface.106.1.2.1.1AttributesandparametersofGCCintheMS.106.1.2.1.2NULL(U0).106.1.2.1.3MMCONNECTIONPENDING(U0.p).106.1.2.1.4GROUPCALLINITIATED(U1).106.1.2.1.5GROUPCALLACTIVE(U2).116.1.2.1.6GROUPCALLPRESENT(U3).116.1.2.1.7GROUPCALLCONNECTIONREQUESTED(U4).116.1.2.1.8TERMINATIONREQUESTED(U5).116.1.2.1.9Sub-statesoftheGroupcallactivestate.116.1.2.1.10GCCTimersintheMS.126.1.2.1.11Consistencyofparametersandstates.126.1.2.2Groupcallcontrolstatesatthenetworksideoftheinterface.136.1.2.2.1NULL(StateN0).136.1.2.2.2GROUPCALLINITIATED(N1).136.1.2.2.3GROUPCALLACTIVE(N2).136.1.2.2.4GROUPCALLESTABLISHMENTPROCEEDING(N3).136.1.2.2.5TERMINATIONREQUESTED(N4).136.2Proceduresforestablishmentofagroupcall.136.2.1Activationofagroupcallbythenetwork.136.2.2Mobileoriginatedestablishment.136.2.2.1Terminationduringmobileoriginatedestablishment.146.2.2.2Abnormalcases.146.2.3MobileterminatinggroupcallestablishmentintheMS.156.3Proceduresduringtheactivestateofagroupcall.156.3.1Mobilestationproceduresintheactivestate.156.3.1.1Sub-statetransitionsintheMS.156.3.2Networkproceduresintheactivestate.166.4Proceduresforrelease,abortion,andterminationofagroupcall.166.4.1Terminationprocedure.166.4.2Abortandreleaseprocedures.166.5Miscellaneousprocedures.176.5.1Statusprocedures.176.5.1.1Getstatusprocedure.176.5.1.2Setparameterprocedure.177Handlingofunknown,unforeseen,anderroneousprotocoldata.177.1General.177.2Messagetooshort.187.3Unknownorunforeseentransactionidentifier.18SIST EN 300 948 V7.0.1:2003

ETSIETSIEN300948V7.0.1(2000-01)4(GSM04.68version7.0.1Release1998)7.4Unknownorunforeseenmessagetype.187.5Non-semanticalmandatoryinformationelementerrors.187.6Unknownandunforeseeninformationelementsinthenon-imperativemessagepart.197.6.1Informationelementsunknowninthemessage.197.6.2Outofsequenceinformationelements.197.6.3RepeatedInformationelements.197.7Non-imperativemessageparterrors.197.7.1SyntacticallyincorrectoptionalInformationelements.197.8Messageswithsemanticallyincorrectcontents.198Messagefunctionaldefinitionsandcontents.208.1CONNECT.208.2GETSTATUS.218.2.1mobileidentity.218.3IMMEDIATESETUP.218.3.1Mobileidentity.228.4SETPARAMETER.228.5SETUP.228.6STATUS.238.6.1Callstate.238.6.2Stateattributes.238.7TERMINATION.248.8TERMINATIONREJECT.248.9TERMINATIONREQUEST.249Contentsofinformationelementsvalueparts.259.1ProtocolDiscriminator.259.2Transactionidentifier.259.3MessageType.259.4Otherinformationelements.269.4.1CallReference.269.4.2Callstate.269.4.3Cause.279.4.4Originatorindication.289.4.6SpareHalfOctet.299.4.7Stateattributes.29AnnexA(informative):ChangeRequestHistory.30History.31SIST EN 300 948 V7.0.1:2003

ETSI5ETSIEN300948V7.0.1(2000-01)(GSM04.68version7.0.1Release1998)IntellectualPropertyRightsIPRsessentialorpotentiallyessentialtothepresentdocumentmayhavebeendeclaredtoETSI.TheinformationpertainingtotheseessentialIPRs,ifany,ispubliclyavailableforETSImembersandnon-members,andcanbefoundinSR000314:"IntellectualPropertyRights(IPRs);Essential,orpotentiallyEssential,IPRsnotifiedtoETSIinrespectofETSIstandards",whichisavailablefromtheETSISecretariat.LatestupdatesareavailableontheETSIWebserver(http://www.etsi.org/ipr).PursuanttotheETSIIPRPolicy,noinvestigation,includingIPRsearches,hasbeencarriedoutbyETSI.NoguaranteecanbegivenastotheexistenceofotherIPRsnotreferencedinSR000314(ortheupdatesontheETSIWebserver)whichare,ormaybe,ormaybecome,essentialtothepresentdocument.ForewordThisEuropeanStandard(Telecommunicationsseries)hasbeenproducedbytheSpecialMobileGroup(SMG).ThepresentdocumentspecifiestheGroupCallControl(GCC)protocolusedbytheVoiceGroupCallService(VGCS)ontheradiointerfacewithinthedigitalcellulartelecommunicationssystem(Phase2+).ThecontentsofthepresentdocumentissubjecttocontinuingworkwithinTC-SMGandmaychangefollowingformalTC-SMGapproval.ShouldTC-SMGmodifythecontentsofthepresentdocument,itwillberesubmittedforOAPbyETSIwithanidentifyingchangeofreleasedateandanincreaseinversionnumberasfollows:Version7.x.y7IndicatesGSMPhase2+Release1998;xtheseconddigitisincrementedforallchangesofsubstance,i.e.technicalenhancements,corrections,updates,etc.;ythethirddigitisincrementedwheneditorialonlychangeshavebeenincorporatedinthespecification.NationaltranspositiondatesDateofadoptionofthisEN:31December1999DateoflatestannouncementofthisEN(doa):31March2000DateoflatestpublicationofnewNationalStandardorendorsementofthisEN(dop/e):30September2000DateofwithdrawalofanyconflictingNationalStandard(dow):30September2000SIST EN 300 948 V7.0.1:2003

ETSIETSIEN300948V7.0.1(2000-01)6(GSM04.68version7.0.1Release1998)1ScopeThepresentdocumentspecifiestheGroupCallControl(GCC)protocolusedbytheVoiceGroupCallService(VGCS)ontheradiointerface.2ReferencesThefollowingdocumentscontainprovisionswhich,throughreferenceinthistext,constituteprovisionsofthepresentdocument.•Referencesareeitherspecific(identifiedbydateofpublication,editionnumber,versionnumber,etc.)ornon-specific.•Foraspecificreference,subsequentrevisionsdonotapply.•Foranon-specificreference,thelatestversionapplies.•Anon-specificreferencetoanETSshallalsobetakentorefertolaterversionspublishedasanENwiththesamenumber.•ForthisRelease1998document,referencestoGSMdocumentsareforRelease1998versions(version7.x.y).[1]GSM01.04(ETR350):"Digitalcellulartelecommunicationsystem(Phase2+);Abbreviationsandacronyms".[2]GSM02.68(ETS300925):"Digitalcellulartelecommunicationsystem(Phase2+);"VoiceGroupCallService(VGCS)-Stage1".[3]GSM03.03(ETS300927):"Digitalcellulartelecommunicationsystem(Phase2+);Numbering,addressingandidentification".[4]GSM03.67(ETS300932):"Digitalcellulartelecommunicationsystem(Phase2+);"enhancedMulti-LevelPrecedenceandPre-emptionservice(eMLPP)-Stage2".[5]GSM03.68(ETS300933):"Digitalcellulartelecommunicationsystem(Phase2+);VoiceGroupCallService(VGCS)-Stage2".[6]GSM04.06(ETS300938):"Digitalcellulartelecommunicationsystem;MobileStation-BaseStationSystem(MS-BSS)interfaceDataLink(DL)layerspecification".[7]GSM04.07(ETS300939):"Digitalcellulartelecommunicationsystem(Phase2+);Mobileradiointerfacesignallinglayer3Generalaspects".[8]GSM04.08(ETS300940):"Digitalcellulartelecommunicationsystem(Phase2+);Mobileradiointerfacelayer3specification".3Definitionsandabbreviations3.1DefinitionsDefinitionsusedinthepresentdocumentarealsodefinedinGSM02.68.Forthepurposesofthepresentdocument,thefollowingtermsanddefinitionsapply.attachmentoftheuserconnection:SeeGSM04.08,subclause5.2.callinguser:GCCentityintheMobileStation(MS)initiatingorhavinginitiatedagroupcall.SIST EN 300 948 V7.0.1:2003

ETSI7ETSIEN300948V7.0.1(2000-01)(GSM04.68version7.0.1Release1998)clearingthecontextrelatedtothegroupcallestablishment:AllrunningGCCtimersintherelevantGCCentityarestopped,allattributesintherelevantGCCentityaredeleted.downlink:Networktomobilestationdirection.groupcall:Isusedinthesamesenseas"voicegroupcall".groupcallchannel:Combineduplink/downlinktobeallocatedineachcellofthegroupcallareaforaparticulargroupcall.Theuplinkcanbeusedbythepresentlytalkingservicesubscriberonly.AllMSsofthelisteningservicesubscribersinonecellshalllistentothecommondownlink.groupreceivemode:SeeGSM04.08.originatingmobilestation:Mobilestationinitiatingorhavinginitiatedthegroupcall.(Notethat,incertainsituations,aMSassumestobetheoriginatingMSofagroupcallwithoutactuallybeingtheoriginatingMSofthatgroupcall.NotethattheremaybeoneornoneoriginatingMSforagivengroupcall.)uplink:Mobilestationtonetworkdirection.3.2AbbreviationsAbbreviationsusedinthepresentdocumentarealsolistedinGSM01.04.Forthepurposesofthepresentdocument,thefollowingabbreviationapplies:GCCGroupCallControl4ApplicabilitySupportofthegroupcallprotocolisoptionalintheMSandinthenetwork.5MainconceptsThepresentdocumentdescribesthegroupcallcontrol(GCC)protocol,whichisoneoftheprotocolsoftheConnectionManagement(CM)sublayer(seeGSM04.07).ThereisingeneralmorethanoneMSengagedinagroupcall.Consequently,thereisingeneralmorethanoneMSwithaGCCentityengagedinthesamegroupcall,andthereisoneGCCentityinthenetworkengagedinthatgroupcall.UnderwhichconditionsaGCCmessageispassedfromlower(sub-)layerstotheGCCentityisdefinedinthespecificationsofthesub-layers.TheMSshallignoreGCCmessagesthatitreceiveswhichweresentinunacknowledgedmodeandwhichexplicitlyspecifyasdestinationamobileidentitywhichisnotamobileidentityoftheMS.HigherlayersandtheMMsub-layerdecidewhentoacceptparallelGCCtransactionsandwhen/whethertoacceptGCCtransactionsinparalleltootherCMtransactions.Thegroupcallmaybeinitiatedbyamobileuserorbyadispatcher.Specificationofaprotocolfordispatchersisoutofthescopeofthepresentdocument.Hence,inthescopeofthepresentdocument,thereare:-oneGCCentityinthenetwork;and-oneormorethanoneGCCentitiesindifferentMSsengagedinagroupcall,andoneorenoneoftheMSsistheoriginatorofthegroupcall(calledtheoriginatingMSinthepresentdocument).Notethat,incertainsituations,aMSassumestobetheoriginatorofagroupcallwithoutbeingtheoriginator.SIST EN 300 948 V7.0.1:2003

ETSIETSIEN300948V7.0.1(2000-01)8(GSM04.68version7.0.1Release1998)TheoriginatoroftheGCCtransactionchoosestheTransactionIdentifier(TI).AMSnotassumingtobetheoriginatorofthetransactionwillchosethetransactionidentifierreceivedfromthenetwork,settingtheTIflagto1+xmod2wherexisthereceivedTIflag.Thepresentdocumentdescribesthegroupcallcontrolprotocolonlywithregardtotwopeerentities,oneinaMS,theotheroneinthenetwork.Thecallcontrolentitiesaredescribedascommunicatingfinitestatemachineswhichexchangemessagesacrosstheradiointerfaceandcommunicateinternallywithotherprotocol(sub)layers.Inparticular,theGCCprotocolusestheMMandRRsublayerspecifiedinGSM04.08.Thisdescriptioninonlynormativeasfarastheconsequentialexternallyobservablebehaviourisconcerned.Forsimplicity,insteadofusingtheterms"GCCentityintheMS"and"GCCentityinthenetwork",thepresentdocumentoftenusestheterms"MS"and"network"ifnoconfusionmayarise.Certainsequencesofactionsofthetwopeerentitiescompose"elementaryprocedures"whichareusedasabasisforthedescriptioninthepresentdocument.Theseelementaryproceduresaredefinedinclause6.ThenetworkshouldapplysupervisoryfunctionstoverifythattheGCCproceduresareprogressingandifnot,takeappropriatemeanstoresolvetheproblems.This,however,isoutofthescopeofthepresentdocument.6ElementaryproceduresforGroupCallControl6.1Overview6.1.1GeneralTheelementaryproceduresmaybegroupedintothefollowingclasses:-groupcallestablishmentprocedures;-groupcallterminationprocedures;-callinformationphaseprocedures;-miscellaneousprocedures.Figure6.1givesanoverviewofthemainstatesandtransitionsontheMSside.SIST EN 300 948 V7.0.1:2003

ETSI9ETSIEN300948V7.0.1(2000-01)(GSM04.68version7.0.1Release1998)MMConnectionpending0.PGCpresent3Null0GCconnectionrequested4Null0GCinitiated1GCactiveTerminationrequested5States1,2,3,4?L:EST-CNF!H:SETUP-IND(g-id,prio)?L:SETUP-IND(g-id,prio)?H:ABORTREQ!L:JOINGCREQ(g-id)?H:JOINGCREQ?H:SETUP-REQ(g-id,prio)!L:EST-REQ(SETUP)?H:TERM.REQ!L:ABORT-REQ!H:TERM.CNF?H:ABORTREQ!L:ABORTREQ?H:IMMSETUPREQ(g-id,prio)!L:EST-REQ(IMMSETUP)or?TimeoutH!TERMCNF?L:DI(TERMINATION)or?L:DI(TERM.REQ)?H:TERM.REQ!L:DR(TERM.REQ)?H:TERM.REQ*!L:DR(TERM.REQ)?Tnochanceexp!L:ABORTREQ?H:ABORTREQ!L:ABORTREQ!H:JOINGCCNF(mode)?L:JOINGCCNF(mode)?L:DI(CONNECT)!H:SETUP-CNF(mode)[MM-est'd](Explicit)!H:TERM-IND?L:DI(TERMINATION)!L:ABORT-REQ**?L:MM-EST_REJ!H:TERM_CONFFigure6.1:Overviewgroupcallcontrolprotocol/MSside*ifMSassumestobetheoriginatorofthegroupcall**ifnotinRRconnectedmodeSIST EN 300 948 V7.0.1:2003

ETSIETSIEN300948V7.0.1(2000-01)10(GSM04.68version7.0.1Release1998)6.1.2Groupcallcontrolstates6.1.2.1GroupcallcontrolstatesattheMSsideoftheinterfaceTheGCCentityoftheMSisdescribedasanextendedfinitestatemachine.Itperformstransitionsbetween(main)states,andinmainstateGROUPCALLACTIVE(U3)itperformstransitionsbetweensub-states.Ithascertainparametersandattributes,e.g.configurationparametersandbehaviourparameters,whichitsetsandchangesbasedoninteractionwithhigherandlower(sub-)layersandonmessageexchangewithitspeerentity.Ifaconfigurationparameterissettoacertainvalue,theMSshallalsoadapttheconfigurationaccordingly.Behaviourparametersdecideon(partof)thebehaviouroftheGCCentity.WhentheGCCentityintheMSreceivesamessage,itshallfirstanalysewhetheritshallignorethemessage,seeclauses5and7.6.1.2.1.1AttributesandparametersofGCCintheMSForthefollowingbehaviourparameters,thedescriptionisinformative.ParameterDescriptionORIGDependingonthecontext,theMSassumestobetheoriginatorofthecall(ORIG=T)ornottobetheoriginatorofthecall(ORIG=F).COMMDependingonthecontext,theMSassumesthatcommunicationwithitspeerentityisenabledinbothdirections(COMM=T)ornot(COMM=F).ForthefollowingconfigurationparameterstheMSshalladaptitsconfigurationaccordingtotheparametervalueandparameterdefinition.ParameterDefinitionD-ATTD-ATT=TmeansthattheMSattachestheuserconnectionforthegroupcallinthedownlink.D-ATT=FmeansthattheMSdoesnotattachtheuserconnectionforthegroupcallinthedownlink.U-ATTU-ATT=TmeansthattheMSattachestheuserconnectionforthegroupcallintheuplink.U-ATT=FmeansthattheMSdoesnotattachtheuserconnectionforthegroupcallintheuplink.6.1.2.1.2NULL(U0)NogroupcallexistsfortheGCCentity.Whenenteringthestate,parametersshallbesettothefollowingvalues,andconfigurationshallbeadaptedtothenewvaluesofconfigurationparameters:ORIG=F,COMM=F,D-ATT=F,U-ATT=F.6.1.2.1.3MMCONNECTIONPENDING(U0.p)TheGCCentityhasrequestedtheexplicitestablishmentofanMMconnection.Whenenteringthestate,parametersshallbesettothefollowingvalues,andconfigurationshallbeadaptedtothenewvaluesofconfigurationparameters:ORIG=T,COMM=F,D-ATT=F,U-ATT=F.6.1.2.1.4GROUPCALLINITIATED(U1)TheGCCentityhasrequestedthepeerentityinthenetworktoestablishagroupcall.Whenenteringthestate,parametersshallbesettothefollowingvalues,andconfigurationshallbeadaptedtothenewvaluesofconfigurationparameters:ORIG=T,COMM=T,D-ATT=F,U-ATT=F.SIST EN 300 948 V7.0.1:2003

ETSI11ETSIEN300948V7.0.1(2000-01)(GSM04.68version7.0.1Release1998)6.1.2.1.5GROUPCALLACTIVE(U2)Thegroupcallisestablishedatleastinonecell;dependingonthesub-state,theMShasattachedtheuserconnectionintheuplinkand/ordownlink.Thefollowingsub-statesexist:-separatelink(U2sl);-waitforreceivemode(U2wr);-receivemode(U2r);-waitforsendandreceivemode(U2ws);-sendandreceivemode(U2sr);-nochannel(U2nc).6.1.2.1.6GROUPCALLPRESENT(U3)TheMShasreceivedanotificationaboutanongoinggroupcall.Higherlayersarerequestedtoacceptorrejectthecall.Whenenteringthestate,parametersshallbesettothefollowingvalues,andconfigurationshallbeadaptedtothenewvaluesofconfigurationparameters:ORIG=F,COMM=F,D-ATT=F,U-ATT=F.6.1.2.1.7GROUPCALLCONNECTIONREQUESTED(U4)TheMShasreceivedanotificationaboutanongoinggroupcall.Higherlayershavedecidedtoacceptthecall.Whenenteringthestate,parametersshallbesettothefollowingvalues,andconfigurationshallbeadaptedtothenewvaluesofconfigurationparameters:ORIG=F,COMM=F,D-ATT=F,U-ATT=F.6.1.2.1.8TERMINATIONREQUESTED(U5)TheMS(whichassumestobetheoriginatorofthegroupcall)hasbeeninstateU1orU2andhassentaTERMINATIONREQUESTmessagetothenetwork.Whenenteringthestate,parametersshallbesettothefollowingvalues,andconfigurationshallbeadaptedtothenewvaluesofconfigurationparameters:ORIG=T,COMM=T,D-ATT=T,U-ATT=T.6.1.2.1.9Sub-statesoftheGroupcallactivestateNOTE:Controloftheuserconnectionattachmentisseenasagroupcallcontrolfunction.Thisisareasonwhythesub-statesaredistinguished.6.1.2.1.9.1separatelink(U2sl)AdedicatedonetooneRRconnectionexistsbetweenMSandnetwork.Whenenteringthesub-state,parametersshallbesettothefollowingvalues,andconfigurationshallbeadaptedtothenewvaluesofconfigurationparameters:COMM=T,D-ATT=T,U-ATT=T.6.1.2.1.9.2waitforreceivemode(U2wr)TheMShasaskedthenetworktoenterreceivemodebutadedicatedone-to-onechannelisstillassigned.Whenenteringthesub-state,parametersshallbesettothefollowingvalues,andconfigurationshallbeadaptedtothenewvaluesofconfigurationparameters:COMM=T,D-ATT=T,U-ATT=F.6.1.2.1.9.3receivemode(U2r)TheMSusesagroupcallchannel.Whenenteringthesub-state,parametersshallbesettothefollowingvalues,andconfigurationshallbeadaptedtothenewvaluesofconfigurationparameters:COMM=F,D-ATT=T,U-ATT=F.SIST EN 300 948 V7.0.1:2003

ETSIETSIEN300948V7.0.1(2000-01)12(GSM04.68version7.0.1Release1998)6.1.2.1.9.4waitforsendandreceivemode(U2ws)TheMS(whichwasinU2rorU2wr)hasaskedfortheuplink.Whenenteringthesub-state,parametersshallbesettothefollowingvalues,andconfigurationshallbeadaptedtothenewvaluesofconfigurationparameters:COMM=F,D-ATT=T,U-ATT=T.6.1.2.1.9.5sendandreceivemode(U2sr)TheMShasbeeninformedbyitspeerentitythattheuplinkisgranted.Whenenteringthesub-state,parametersshallbesettothefollowingvalues,andconfigurationshallbeadaptedtothenewvaluesofconfigurationparameters:D-ATT=T,U-ATT=T.6.1.2.1.9.6nochannel(U2nc)TheGCCentityhasbeeninformedthatnochanneliscurrentlyavailable.TimerTnochannellisrunning.Whenenteringthesub-state,parametersshallbesettothefollowingvalues,andconfigurationshallbeadaptedtothenewvaluesofconfigurationparameters:COMM=F,D-ATT=T,U-ATT=T.6.1.2.1.10GCCTimersintheMSTable6.1specifiesthetimersusedinGCC.Thedenotationofcolumnsisdefinedasfollows:timer::=nameofthetimer;set::=underwhichconditionsthetimerisset(i.e.,started);stopped::=underwhichconditionsthetimerisstopped;runninginstate(s)::=inwhichstate(s)thetimermayberunning;actionatexpiry::=whichactionstheGCCentityshallperformatexpiry;value::=thedurationbetweensettingthetimerandexpiryofthetimer("s"denotes"second(s)""xx-yy"meansthatanyvaluebetweenxxandyyispermitted).Table6.1:SpecificationoftimersusedinGCCtimersetstoppedrunninginstate(s)actionatexpiryvalueTnochannelwhenenteringU2ncwhenleavingU2ncU2ncseesubclause6.3.13sTMM-estwhenenteringU0.pusingtheset-upprocedurewhenenteringU1usingtheimmediateset-upprocedurewhenleavingU0.porU1U0.p,U1seesubclause6.2.15sTtermwhensendingaTERMINATIONREQUESTwhenreceivingaTERMINATIONorTERMINATIONREJECTU5abortgroupcall10sTconnreqwhenenteringstateU4whenleavingstateU4U4abortgroupcall10-30s6.1.2.1.11ConsistencyofparametersandstatesTheMSshallconsiderthefollowingparametervaluesasinconsistentwiththestateorsub-state:ORIG=TisinconsistentwithstatesU3andU4.COMM=TisinconsistentwithstatesU0,U3,U4,andwithsub-statesU2ncandU2rofstateU2.SIST EN 300 948 V7.0.1:2003

ETSI13ETSIEN300948V7.0.1(2000-01)(GSM04.68version7.0.1Release1998)AllothervaluesofparametersORIG,COMM,D-ATT,andU-ATTshallnotbeconsideredbytheMSasinconsistentwithastateorsub-state.6.1.2.2Groupcallcontrolstatesatthenetworksideoftheinterface6.1.2.2.1NULL(StateN0)NogroupcallexistsfortheGCCentity.6.1.2.2.2GROUPCALLINITIATED(N1)TheGCCentityhasreceivedtheindicationthatapeerentityinaMSwantstoestablishagroupcallforacertaingroupidentity.6.1.2.2.3GROUPCALLACTIVE(N2)Thegroupcallisestablishedinatleastonecell;theremaybeaMSwhichhasseizedtheuplinkornot;theremaybetalkingdispatchersornot.6.1.2.2.4GROUPCALLESTABLISHMENTPROCEEDING(N3)TheGCCentitywantstoacceptthegroupcall,hasinitiatedestablishmentofcorrespondinggroupcallchannels,and,ifthereisacallinguser.hassentaCONNECTmessagetothecallinguser(ifthereisacallinguser).6.1.2.2.5TERMINATIONREQUESTED(N4)TheGCCentityhasaskedlowersub-layerstoterminatethegroupcallinallcellsandwaitsforaconfirmationthatthegroupcallhasbeenterminatedinallcells.6.2Proceduresforestablishmentofagroupcall6.2.1ActivationofagroupcallbythenetworkTheGCCentityinthenetworkmayinitiatetheactivationofagroupcallwithacertaingroupcallreferenceandpriorityinalistofcellsbyaskinglowerlayerstoestablishthegroupcallwiththatgroupcallreferenceandpriorityinthosecells.Itthenwaitsuntilitisinformedbylower(sub-)layersthatresourceactivationwassufficientlysuccessful,andentersstateN2,GCACTIVE.6.2.2Mobileoriginatedesta
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