SIST EN 300 938 V8.0.1:2003
(Main)Digital cellular telecommunications system (Phase 2+) (GSM); Mobile Station - Base Station System (MS - BSS) interface; Data Link (DL) layer specification (GSM 04.06 version 8.0.1 Release 1999)
General Information
- Abstract
upgrade to R99
- Status
- Published
- Publication Date
- 30-Nov-2003
- Current Stage
- 6060 - National Implementation/Publication (Adopted Project)
- Start Date
- 01-Dec-2003
- Due Date
- 01-Dec-2003
- Completion Date
- 01-Dec-2003
Overview
SIST EN 300 938 V8.0.1:2003 defines the Data Link (DL) layer specification for the Mobile Station - Base Station System (MS - BSS) interface within the Digital Cellular Telecommunications System (GSM Phase 2+), specifically aligning with Release 1999 (R99). This standard, aligned with GSM 04.06 version 8.0.1, is essential for ensuring reliable and standardized communications over the GSM radio interface between user equipment and the network infrastructure.
This document, published by the Slovenski inštitut za standardizacijo (SIST), mirrors the ETSI European Norm and facilitates interoperability, efficient signaling, and robust data transmission in GSM networks.
Key Topics
- Data Link Layer Protocol: Defines the operation of the Link Access Procedure on the Dm channel (LAPDm), which is responsible for error detection, correction, and reliable delivery of signaling messages.
- Frame Structure: Details formats for all types of DL layer frames (A, B, Bbis, Bter, B4, and C) used in peer-to-peer communications over different GSM logical channels.
- Operational Modes:
- Unacknowledged operation via unnumbered information (UI) frames.
- Acknowledged operation using a multiple-frame procedure for reliable data transfer.
- Peer-to-Peer and Layer-to-Layer Communication: Outlines procedures and primitive types (e.g., requests, indications, responses, confirms) and defines the mapping to logical GSM channels.
- Error Handling: Specifies procedures for managing parameter errors in address, control, and length indicator fields, supporting system robustness.
- Options: Highlights optional use of the short L2 headertype 1, which can enhance network efficiency under specific conditions.
Applications
- GSM Network Infrastructure: Implements standardized data link layer protocols to ensure consistent communication between mobile stations (MS) and the base station system (BSS).
- Mobile Device Firmware: Forms the basis for coding the DL layer in GSM handsets, providing assured interoperability and compliance with global GSM networks.
- Testing and Certification: Serves as a reference for manufacturers and network operators during device and system validation processes.
- Network Upgrades: Supports system evolution from earlier GSM releases to Release 1999, enabling new feature support and enhanced network services.
In practice, the correct implementation of this standard allows for:
- Reliable signaling over the GSM air interface, essential for call setup, SMS delivery, and mobility management.
- Flexible and robust handling of communication errors and channel changes, ensuring uninterrupted user experience.
- Seamless handover and random access procedures, critical in mobile environments.
Related Standards
For comprehensive GSM Phase 2+ network deployment and compatibility, consider these related standards:
- GSM 04.01: General aspects and principles of the MS - BSS interface.
- GSM 04.03: Defines channel structures and access capabilities in GSM.
- GSM 04.05: General aspects of the Data Link (DL) layer.
- GSM 04.07/04.08: Radio interface signaling and supplementary services specifications.
- GSM 05.02: Multiplexing and multiple access on the GSM radio path.
- GSM 08.56/08.58: BSC - BTS interface layer 2/3 specifications.
Practical Value
Adopting SIST EN 300 938 V8.0.1 ensures:
- Full alignment with international GSM standards, critical for global device and infrastructure compatibility.
- Optimized signaling and system performance in GSM R99 environments.
- Enhanced support for roaming, interoperability, and network reliability in both legacy and modernized mobile communication networks.
Keywords: GSM standard, data link layer, LAPDm, MS - BSS interface, mobile telecommunications, signaling protocol, Release 1999, system interoperability, SIST EN 300 938.
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Frequently Asked Questions
SIST EN 300 938 V8.0.1:2003 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Digital cellular telecommunications system (Phase 2+) (GSM); Mobile Station - Base Station System (MS - BSS) interface; Data Link (DL) layer specification (GSM 04.06 version 8.0.1 Release 1999)". This standard covers: upgrade to R99
upgrade to R99
SIST EN 300 938 V8.0.1:2003 is classified under the following ICS (International Classification for Standards) categories: 33.070.50 - Global System for Mobile Communication (GSM). The ICS classification helps identify the subject area and facilitates finding related standards.
SIST EN 300 938 V8.0.1:2003 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Digital cellular telecommunications system (Phase 2+) (GSM); Mobile Station - Base Station System (MS - BSS) interface; Data Link (DL) layer specification (GSM 04.06 version 8.0.1 Release 1999)33.070.50Globalni sistem za mobilno telekomunikacijo (GSM)Global System for Mobile Communication (GSM)ICS:Ta slovenski standard je istoveten z:EN 300 938 Version 8.0.1SIST EN 300 938 V8.0.1:2003en01-december-2003SIST EN 300 938 V8.0.1:2003SLOVENSKI
STANDARD
ETSIEN300938V8.0.1(2000-09)EuropeanStandard(Telecommunicationsseries)Digitalcellulartelecommunicationssystem(Phase2+);MobileStation-BaseStationSystem(MS-BSS)interface;DataLink(DL)layerspecification(GSM04.06version8.0.1Release1999)GLOBALSYSTEMFORMOBILECOMMUNICATIONSRSIST EN 300 938 V8.0.1:2003
ETSIETSIEN300938V8.0.1(2000-09)2(GSM04.06version8.0.1Release1999)ReferenceREN/SMG-020406Q8KeywordsDigitalcellulartelecommunicationssystem,GlobalSystemforMobilecommunications(GSM)ETSI650RoutedesLuciolesF-06921SophiaAntipolisCedex-FRANCETel.:+33492944200Fax:+33493654716SiretN°34862356200017-NAF742CAssociationàbutnonlucratifenregistréeàlaSous-PréfecturedeGrasse(06)N°7803/88ImportantnoticeIndividualcopiesofthepresentdocumentcanbedownloadedfrom:http://www.etsi.orgThepresentdocumentmaybemadeavailableinmorethanoneelectronicversionorinprint.Inanycaseofexistingorperceiveddifferenceincontentsbetweensuchversions,thereferenceversionisthePortableDocumentFormat(PDF).Incaseofdispute,thereferenceshallbetheprintingonETSIprintersofthePDFversionkeptonaspecificnetworkdrivewithinETSISecretariat.Usersofthepresentdocumentshouldbeawarethatthedocumentmaybesubjecttorevisionorchangeofstatus.InformationonthecurrentstatusofthisandotherETSIdocumentsisavailableathttp://www.etsi.org/tb/status/Ifyoufinderrorsinthepresentdocument,sendyourcommentto:editor@etsi.frCopyrightNotificationNopartmaybereproducedexceptasauthorizedbywrittenpermission.Thecopyrightandtheforegoingrestrictionextendtoreproductioninallmedia.©EuropeanTelecommunicationsStandardsInstitute2000.Allrightsreserved.SIST EN 300 938 V8.0.1:2003
ETSIETSIEN300938V8.0.1(2000-09)3(GSM04.06version8.0.1Release1999)ContentsIntellectualPropertyRights.7Foreword.70Scope.80.1References.80.2Abbreviations.81General.91.1Options.92Framestructureforpeer-to-peercommunication.102.1General.102.2Framedelimitationandfillbits.122.3Addressfield.122.4Controlfield.132.5Lengthindicatorfield.132.5aShortL2headertype1.132.6Informationfield.132.7Transparency.132.8Formatconvention.132.8.1Numberingconvention.132.8.2Orderofbittransmission.132.8.3Fieldmappingconvention.133ElementsofproceduresandformatsoffieldsforDataLinkLayerpeer-to-peercommunication.143.1General.143.2Addressfieldformat.143.3Addressfieldvariables.153.3.1Addressfieldextensionbit(EA).153.3.2Command/responsefieldbit(C/R).153.3.3Serviceaccesspointidentifier(SAPI).153.4Controlfieldformats.153.4.1Informationtransferformat-I.153.4.2Supervisoryformat-S.163.4.3Unnumberedformat-U.163.4aShortL2headertype1.163.5Controlfieldparametersandassociatedstatevariables.163.5.1Poll/Finalbit.163.5.2Multipleframeoperation-variablesandsequencenumbers.173.5.2.1Modulus.173.5.2.2SendstatevariableV(S).173.5.2.3AcknowledgestatevariableV(A).173.5.2.4SendsequencenumberN(S).173.5.2.5ReceivestatevariableV(R).173.5.2.6ReceivesequencenumberN(R).173.5.2.7Otherparametersandvariables.183.5.3Unacknowledgedoperationvariablesandparameters.183.6Lengthindicatorfieldformat.183.7Lengthindicatorfieldvariables.183.7.1Lengthindicatorfieldextensionbit(EL).183.7.2Moredatabit(M).183.7.3Lengthindicator(L).183.8Commandsandresponses.193.8.1Information(I)commands.193.8.2Setasynchronousbalancedmode(SABM)command.193.8.3Disconnect(DISC)command.203.8.4Unnumberedinformation(UI)command.203.8.5Receiveready(RR)command/response.20SIST EN 300 938 V8.0.1:2003
ETSIETSIEN300938V8.0.1(2000-09)4(GSM04.06version8.0.1Release1999)3.8.6Reject(REJ)command/response.213.8.7Receivenotready(RNR)command/response.213.8.8Unnumberedacknowledgement(UA)response.213.8.9Disconnectedmode(DM)response.214Elementsforlayer-to-layercommunication.224.1Definitionofprimitivesandparameters.224.1.1Genericnames.224.1.1.1DL-ESTABLISH.224.1.1.2DL-RELEASE.224.1.1.3DL-DATA.224.1.1.4DL-UNITDATA.224.1.1.5DL-SUSPEND.224.1.1.6DL-RESUME.224.1.1.7DL-RECONNECT.234.1.1.8DL-RANDOMACCESS.234.1.1.9MDL-RELEASE.234.1.1.10MDL-ERROR.234.1.1.11PH-DATA.234.1.1.12PH-RANDOMACCESS.234.1.1.13PH-CONNECT.234.1.1.14PH-READY-TO-SEND.234.1.1.15PH-EMPTY-FRAME.234.1.2Primitivestypes.234.1.2.1REQUEST.244.1.2.2INDICATION.244.1.2.3RESPONSE.244.1.2.4CONFIRM.244.1.3Parameterdefinition.254.1.3.1Messageunit.254.1.3.2Channeltype.254.1.3.3ServiceAccessPoint.254.1.3.4Releasemode.254.1.3.5Errorcause.254.1.3.6Establishmode.264.1.3.7L2headertype.264.1.3.8Priority.264.2Primitiveprocedures.305Definitionofthepeer-to-peerprotocolLAPDm.305.1General.305.2GeneralProtocolProcedures.315.2.1Unacknowledgedinformationtransfer.315.2.2Acknowledgedmultipleframeinformationtransfer.325.3Proceduresforunacknowledgedinformationtransfer.325.3.1General.325.3.2Transmissionofunacknowledgedinformation.325.3.3Receiptofunacknowledgedinformation.325.4Proceduresforestablishmentandreleaseofmultipleframeoperation.325.4.1Establishmentofmultipleframeoperation.325.4.1.1General.325.4.1.2Normalestablishmentprocedures.335.4.1.3ProcedureonexpiryoftimerT200:Normalestablishment.345.4.1.4Contentionresolutionestablishmentprocedure.345.4.1.5ProcedureonexpiryoftimerT200:contentionresolution(MSonly).365.4.2Informationtransfer.365.4.2.1Generalrequirements.365.4.2.2Errorconditions.365.4.2.3Fillframes.375.4.3Suspensionandresumptionofmultipleframeoperation.385.4.3.1General.385.4.3.2Suspension.38SIST EN 300 938 V8.0.1:2003
ETSIETSIEN300938V8.0.1(2000-09)5(GSM04.06version8.0.1Release1999)5.4.3.3Resumption.395.4.3.3.1Procedureafterchannelchange.395.4.3.3.2Procedureafterreturningtotheoldchannel(MSonly).395.4.4Terminationofmultipleframeoperation.405.4.4.1General.405.4.4.2Normalreleaseprocedure.405.4.4.3ProcedureonexpiryoftimerT200fornormalrelease.405.4.4.4Localendreleaseprocedure.415.4.5Idlestate.415.4.6Collisionofunnumberedcommandsandresponses.415.4.6.1Identicaltransmittedandreceivedcommands.415.4.6.2Differenttransmittedandreceivedcommands.425.4.6.3UnsolicitedDMresponseandSABMorDISCcommand.425.5Proceduresforinformationtransferinmultipleframeoperation.425.5.1TransmittingIframes.425.5.2ReceivingIframes.435.5.2.1PbitofthereceivedIframesetto"1".435.5.2.2PbitofthereceivedIframesetto"0".435.5.3Receivingacknowledgement.445.5.3.1OnreceiptofavalidIframe.445.5.3.2ReceivingsupervisorycommandframeswiththePbitsetto"1".445.5.4ReceivingREJframes.445.5.4.1ReceiptofavalidREJframe.445.5.4.2Transmittingframes.455.5.5ReceivingRNRframe.455.5.6Datalinklayerownreceiverbusycondition.465.5.7Waitingacknowledgement.475.5.8Preemption.475.5.8.1SenderRequirements.485.5.8.2ReceiverRequirements.485.6Abnormalreleaseandre-establishmentofmultipleframeoperation.485.6.1Criteriaforre-establishment.485.6.2Criteriaforabnormalrelease.485.6.3Proceduresforre-establishment.495.6.4Proceduresforabnormalrelease.495.7Exceptionconditionreportingandrecoveryformultipleframeoperation.495.7.1N(S)sequenceerror.495.7.2Timerrecovery.505.7.3Invalidframecondition.505.7.4N(R)sequenceerror.505.8Listofsystemparameters.505.8.1TimerT200.515.8.1.1ForSAPI=0andSAPI=3.515.8.1.2ForSAPIsotherthan0or3.515.8.2Maximumnumberofretransmissions(N200).515.8.2.1ForSAPI=0and3.515.8.2.2ForSAPIsotherthan0or3.515.8.3MaximumnumberofoctetsinanI,UI,SABMandUAframepartiallyorentirelyavailablefortheinformationfield(N201).515.8.4MaximumnumberofoutstandingIframes(k).525.8.5MaximumnumberofoctetsinaLayer3message.525.9Systemperformancerequirements.526SpecialprotocoloperationonSAPI=0andSAPI=3.53AnnexA(normative):Randomaccessprocedures.54A.1Descriptionoftheprocedure.54A.1.1ProcedureintheMS.54A.1.2ProcedureintheBS.54SIST EN 300 938 V8.0.1:2003
ETSIETSIEN300938V8.0.1(2000-09)6(GSM04.06version8.0.1Release1999)A.2Format.54AnnexG(normative):Handlingofframeswithparametererrorsintheaddress,controlandlengthindicatorfields.55G.1General.55G.2Parametererrorsintheaddressfield.55G.2.1UnallocatedSAPI.55G.2.2WrongvalueoftheC/Rbit.55G.2.3EAbitsetto"0".55G.3Parametererrorsinthecontrolfield.56G.3.1Supervisoryframes.56G.3.2Unnumberedframes.56G.4Parametererrorsinthelengthindicatorfield.56G.4.1ELbiterror.56G.4.2Informationframes.56G.4.3Supervisoryframes.57G.4.4DISCandDMframes.57G.4.5SABMUAandUIframes.57AnnexH(informative):ChangeRequestHistory.58History.59SIST EN 300 938 V8.0.1:2003
ETSIETSIEN300938V8.0.1(2000-09)7(GSM04.06version8.0.1Release1999)IntellectualPropertyRightsIPRsessentialorpotentiallyessentialtothepresentdocumentmayhavebeendeclaredtoETSI.TheinformationpertainingtotheseessentialIPRs,ifany,ispubliclyavailableforETSImembersandnon-members,andcanbefoundinETSISR000314:"IntellectualPropertyRights(IPRs);Essential,orpotentiallyEssential,IPRsnotifiedtoETSIinrespectofETSIstandards",whichisavailablefromtheETSISecretariat.LatestupdatesareavailableontheETSIWebserver(http://www.etsi.org/ipr).PursuanttotheETSIIPRPolicy,noinvestigation,includingIPRsearches,hasbeencarriedoutbyETSI.NoguaranteecanbegivenastotheexistenceofotherIPRsnotreferencedinETSISR000314(ortheupdatesontheETSIWebserver)whichare,ormaybe,ormaybecome,essentialtothepresentdocument.ForewordThisEuropeanStandard(Telecommunicationsseries)hasbeenproducedbyETSITechnicalCommitteeSpecialMobileGroup(SMG).ThepresentdocumentdefinesthedatalinklayerprotocoloftheMobileStation-BaseStationSystem(MS-BSS)interfacewithinthedigitalcellulartelecommunicationssystem.ThecontentsofthepresentdocumentissubjecttocontinuingworkwithinSMGandmaychangefollowingformalSMGapproval.ShouldSMGmodifythecontentsofthepresentdocument,itwillbere-releasedwithanidentifyingchangeofreleasedateandanincreaseinversionnumberasfollows:Version8.x.ywhere:8indicatesRelease1999ofGSMPhase2+.xtheseconddigitisincrementedforallchangesofsubstance,i.e.technicalenhancements,corrections,updates,etc.ythethirddigitisincrementedwheneditorialonlychangeshavebeenincorporatedinthespecification.ThespecificationfromwhichthepresentdocumenthasbeenderivedwasoriginallybasedonCEPTdocumentation,hencethepresentationofthepresentdocumentmaynotbeentirelyinaccordancewiththeETSIdraftingrules.AnnexesBtoFweredeletedfromtheoriginalspecification,however,forreferencingpurposestheannexnumberinghasbeenmaintained.NationaltranspositiondatesDateofadoptionofthisEN:25August2000DateoflatestannouncementofthisEN(doa):30November2000DateoflatestpublicationofnewNationalStandardorendorsementofthisEN(dop/e):31May2001DateofwithdrawalofanyconflictingNationalStandard(dow):31May2001SIST EN 300 938 V8.0.1:2003
ETSIETSIEN300938V8.0.1(2000-09)8(GSM04.06version8.0.1Release1999)0ScopeThepresentdocumentdefinesadatalinklayerprotocoltobeusedforsignalling,andpossiblyalsoforotherapplications,ontheMS-BSinterface.0.1ReferencesThefollowingdocumentscontainprovisionswhich,throughreferenceinthistext,constituteprovisionsofthepresentdocument.• Referencesareeitherspecific(identifiedbydateofpublication,editionnumber,versionnumber,etc.)ornon-specific.• Foraspecificreference,subsequentrevisionsdonotapply.• Foranon-specificreference,thelatestversionapplies.• Anon-specificreferencetoanETSshallalsobetakentorefertolaterversionspublishedasanENwiththesamenumber.• ForthisRelease1999document,referencestoGSMdocumentsareforRelease1999versions(version8.x.y).[1]GSM01.04:"Digitalcellulartelecommunicationssystem(Phase2+);Abbreviationsandacronyms".[2]GSM04.01:"Digitalcellulartelecommunicationssystem;MobileStation-BaseStationSystem(MS-BSS)interface;Generalaspectsandprinciples".[3]GSM04.03:"Digitalcellulartelecommunicationssystem(Phase2+);MobileStation-BaseStationSystem(MS-BSS)interfaceChannelstructuresandaccesscapabilities".[4]GSM04.04:"Digitalcellulartelecommunicationssystem;Layer1Generalrequirements".[5]GSM04.05:"Digitalcellulartelecommunicationssystem;DataLink(DL)layerGeneralaspects".[6]GSM04.07:"Digitalcellulartelecommunicationssystem(Phase2+);Mobileradiointerfacesignallinglayer3;Generalaspects".[7]GSM04.08:"Digitalcellulartelecommunicationssystem(Phase2+);Mobileradiointerfacelayer3specification".[8]GSM04.10:"Digitalcellulartelecommunicationssystem;Mobileradiointerfacelayer3Supplementaryservicesspecification;Generalaspects".[9]GSM04.12:"Digitalcellulartelecommunicationssystem(Phase2+);ShortMessageServiceCellBroadcast(SMSCB)supportonthemobileradiointerface".[10]GSM05.02:"Digitalcellulartelecommunicationssystem(Phase2+);Multiplexingandmultipleaccessontheradiopath".[11]GSM08.56:"Digitalcellulartelecommunicationssystem;BaseStationController-BaseTransceiverStation(BSC-BTS)interface;Layer2specification".[12]GSM08.58:"Digitalcellulartelecommunicationssystem(Phase2+);BaseStationController-BaseTransceiverStation(BSC-BTS)interface;Layer3specification".[13]CCITTRecommendationZ.100:"Specificationanddescriptionlanguage(SDL)".0.2AbbreviationsAbbreviationsusedinthepresentdocumentarelistedinGSM01.04.SIST EN 300 938 V8.0.1:2003
ETSIETSIEN300938V8.0.1(2000-09)9(GSM04.06version8.0.1Release1999)1GeneralThepresentdocumentdescribestheframestructure,elementsofprocedure,formatoffieldsandproceduresfortheproperoperationoftheLinkAccessProcedureontheDmchannel,LAPDm.NOTE1:ThetermDmchannelisusedforconveniencetodesignatethecollectionofallthevarioussignallingchannelsrequiredintheGSMsystem.SeealsoGSM04.03.Theconcepts,terminology,overviewdescriptionofLAPDmfunctionsandprocedures,andtherelationshipwithotherTechnicalSpecificationsaredescribedingeneraltermsinGSM04.05.TheframeformatsdefinedforLAPDmarebasedonthosedefinedforLAPD.However,thereareimportantdifferencesbetweenLAPDmandLAPD,inparticularwithregardtoframedelimitationmethodsandtransparencymechanisms.Thesedifferencesarenecessaryforoperationwithintheconstraintssetbytheradiopath.LAPDmsupportstwomodesofoperation:-unacknowledgedoperationusingUIframes;-acknowledgedoperationusingthemultipleframeprocedure.Asachoiceofimplementation,thetwomodesofoperationmaybeimplementedindependentlyofeachother.Thisispossiblesincethereisnointeractionsbetweenthetwomodes,otherthanqueuingatthetransmitter,evenwhentheycoexistonthesamephysicalchannel.ForBCCHsandCCCHsonlytheunacknowledgedmodeofoperationneedstobeimplemented.LAPDmisusedforinformationsentonthecontrolchannelsBCCH,AGCH,NCH,PCH,FACCH,SACCHandSDCCHasdefinedinGSM04.03.NOTE2:AGCH,NCHandPCHaresometimesreferredtobythecollectivenameCCCHandFACCH,SACCHandSDCCHare,similarly,referredtobythecollectivenameDCCH.LAPDmmayalsobeusedonothertypesofchannel.NOTE3:AsstatedinGSM04.05,theterm"datalinklayer"isusedinthemaintextofthisTechnicalSpecification.However,mainlyinfiguresandtables,theterms"layer2"and"L2"areusedasabbreviations.Furthermore,inaccordancewithGSM04.07andGSM04.08,theterm"layer3"isusedtoindicatethelayerabovethedatalinklayer.ThisTechnicalSpecificationisorganizedasfollows:Theframestructureforpeer-to-peercommunicationisgiveninclause2.Theelementsofprocedureandformatsoffieldsaregiveninclause3.Theelementsoflayer-to-layercommunicationarecontainedinclause4.Thedetailsofthepeer-to-peerproceduresaregiveninclause5.Section6summarizesthespecialprotocoloperationsusedmandatorilywithSAPI=0andSAP=3.ThespecificationfortherandomaccesschanneliscontainedinannexA,eventhoughitisnotaLAPDmfunction.Thepresentdocumentisdescriptiveanddoesnotconstraintheimplementationoftherandomaccessfunction.TheprocedureisusedforCHANNELREQUESTontheRACHandHANDOVERACCESSonthemainDCCH.(AnnexesBtoFaredeleted).AnnexGgivesanoverviewofactionstakenonframescontainingparametererrors.1.1OptionsSupportofshortL2headertype1isanoptioninboththemobilestationandthenetwork;undercertainconditionsthesupportismandatory,asspecifiedinotherSpecifications.Alayer2protocolentitynotimplementingshortL2headertype1shalldiagnoseanE/AbiterrorandproceedasdefinedinannexG.2.3.SIST EN 300 938 V8.0.1:2003
ETSIETSIEN300938V8.0.1(2000-09)10(GSM04.06version8.0.1Release1999)2Framestructureforpeer-to-peercommunication2.1GeneralAlldatalinklayerpeer-to-peerexchangesareinframesconformingtooneoftheformatsshowninfigure1.Severalformattypesareshowninthefigure:-FormatAisusedonDCCHsforframeswherethereisnoinformationfield.-FormatsB,BterandB4areusedonDCCHsforframescontaininganinformationfield:-formatBterisusedonrequestofhigherlayersifandonlyifshortL2headertype1issupportedandaUIcommandistobetransmittedonSAPI0;-formatB4isusedforUIframestransmittedbythenetworkonSACCH;-formatBisappliedinallothercases.-FormatBbisisusedonlyonBCCH,PCH,NCH,andAGCH.-InadditionthereisaFormatCfortransmissionofrandomaccesssignals.FormatCframesaredescribedinannexA.FormatA,B,Bbis,BterandB4framesaredescribedintheremainderofthepresentdocument.Bit87654321OctetNo1:Addressfield:kControlfieldk+1k+2:Lengthindicatorfield:nn+1:Fillbits:N201+nFormattypeAFigure1/GSM04.06(sheet1of3):GeneralframeformatsSIST EN 300 938 V8.0.1:2003
ETSIETSIEN300938V8.0.1(2000-09)11(GSM04.06version8.0.1Release1999)Bit87654321OctetNo1:Addressfield:kControlfieldk+1k+2:Lengthindicatorfield:nn+1:Informationfield:NN+1:Fillbits:N201+nFormattypeBBit87654321OctetNo1:::Informationfield:::N201FormattypeBbisFigure1/GSM04.06(sheet2of3):GeneralframeformatsSIST EN 300 938 V8.0.1:2003
ETSIETSIEN300938V8.0.1(2000-09)12(GSM04.06version8.0.1Release1999)Bit87654321OctetNo1:Addressfield:kControlfieldk+1k+2:Informationfield:N201+k+1FormattypeB4Bit87654321OctetNoshortL2headertype112:Informationfield:::N201FormattypeBterFigure1/GSM04.06(sheet3of3):GeneralframeformatsTheparameterN201isthemaximumnumberofoctetswhicharepartiallyorentirelyavailablefortheinformationfieldofaframe.Itdependsonthetypeofchannelandtheformat,seesubclause5.8.3.2.2FramedelimitationandfillbitsFramedelimitationisprovidedbythephysicallayer:-informattypeA,BandB4framesatthebeginningoftheframefordeterminingthestartofthefirstoctetintheaddressfield,informattypeBterframesfordeterminingthestartoftheoctetcontainingtheshortL2headertype1(whichisalsothefirstoctetusedfortheinformationfield),andinformattypeBbisframesfordeterminingthestartofthefirstoctetfortheinformationfield;-attheendoftheframefordeterminingthelastbitoftheframe.Theendoftheusefulpartoftheframe,i.e.theendofthelengthindicatorfieldintypeAframesandtheendoftheinformationfieldintypeBframes,isdeterminedbyalengthindicatorcontainedinthelengthindicatorfield.TheusefulpartofaBbisframestakesallN201octetsofthatframe.TheusefulpartofaBterframetakesallN201octetsofthatframeexceptthosebitsofoctet1whichcontaintheshortL2headertype1.TheusefulpartofaB4frametakesallN201octetsofthatframeexceptthoseoctetswhichcontaintheaddressfieldandthecontrolfield.IfaframecontainsalengthindicatorhasavaluelessthanN201,theframecontainsfillbits.Octetscontainingfillbitsshalltakethebinaryvalue"00101011",whensentbythenetwork.Octetscontainingfillbitsshalltakethevalue"00101011"or"11111111",whensentbythemobilestation.NOTE:Thevalue"00101011"ischosenduetothemodulationandinterleavingschemeusedintheGSMsystem.2.3AddressfieldTheaddressfieldmayconsistofavariablenumberofoctets.However,forapplicationsoncontrolchannelsthefieldconsistsofonlyoneoctet.TheaddressfieldidentifiestheSAPforwhichacommandframeisintendedandtheSAPtransmittingaresponseframe.Theformatoftheaddressfieldisdefinedinsubclause3.2.SIST EN 300 938 V8.0.1:2003
ETSIETSIEN300938V8.0.1(2000-09)13(GSM04.06version8.0.1Release1999)2.4ControlfieldThecontrolfieldconsistsofoneoctet.Theformatofthecontrolfieldisdefinedinsubclause3.4.2.5LengthindicatorfieldThelengthindicatorfieldmayconsistofavariablenumberofoctets.However,forapplicationsoncontrolchannelsthefieldconsistsofonlyoneoctet.Theformatofthefieldisdefinedinsubclause3.6.2.5aShortL2headertype1TheshortL2headertype1consistsoftwobits.Itscontentsaredefinedinsubclause3.4a.2.6InformationfieldTheinformationfieldofaframe,whenpresent,hasthepositionintheframedefinedin2.1.Themaximumnumberofoctetsintheinformationfield(N201)isdefinedinsubclause5.8.3.2.7TransparencyBecauseoftheframedelimitationtechniqueused(seesubclause2.2),theframecanincludeanypossiblesequenceofbitswithouttheneedforadditionaltransparencymechanisms.2.8Formatconvention2.8.1NumberingconventionThebasicconventionusedinthisTechnicalSpecificationisillustratedinfigure2.Thebitsaregroupedintooctets.Thebitsofanoctetareshownhorizontallyandarenumberedfrom1to8.Multipleoctetsareshownverticallyandarenumberedfrom1ton.Bit87654321Octetno12;;nFigure2/GSM04.06:Formatconvention2.8.2OrderofbittransmissionTheorderofbittransmissionisdefinedinGSM04.04.2.8.3FieldmappingconventionWhenafieldiscontainedwithinasingleoctet,thelowestbitnumberofthefieldrepresentsthelowestordervalue.Whenafieldspansmorethanoneoctet,theorderofbitvalueswithineachoctetprogressivelydecreasesastheoctetnumberincreases.Inthatpartofthefieldcontainedinagivenoctetthelowestbitnumberrepresentsthelowestordervalue.SIST EN 300 938 V8.0.1:2003
ETSIETSIEN300938V8.0.1(2000-09)14(GSM04.06version8.0.1Release1999)Forexample,abitnumbercanbeidentifiedasacouple(o,b)whereoistheoctetnumberandbistherelativebitnumberwithintheoctet.Figure3illustratesafieldthatspansfrombit(1,3)tobit(2,7).Thehighorderbitofthefieldismappedonbit(1,3)andtheloworderbitismappedonbit(2,7).Bit876543214321stoctetfield222102ndoctetfield22Figure3/GSM04.06:Fieldmappingconvention3ElementsofproceduresandformatsoffieldsforDataLinkLayerpeer-to-peercommunication3.1GeneralTheelementsofproceduresdefinethecommandsandresponsesthatareusedonthedatalinkconnectionscarriedontheDmchannel.Proceduresarederivedfromtheseelementsofproceduresandaredescribedinclause5.Ifabitpositionismarkedas"spare",itshallbecodedas"0".Forfuturecompatibilityreasons,anentityreceivingframes,wheresparebitpositionsarecodedotherwise,shallignorethosevalueswithoutnotificationofanyerror.3.2AddressfieldformatThefieldconsistsof:-theaddressfieldextensionbitEA;-thecommand/responsebitC/R;-theSAPI;-andtheLinkProtocolDiscriminatorLPD.Theformatoftheaddressfieldforcontrolchannelsisshowninfigure4.Theaddressfieldextensionbit,EA,enablesextensionofthefieldtospanmorethanoneoctet.Thevalue"0"isusedtoindicateanextension,thevalue"1"shallbeusedforthefinaladdressfieldoctet.TheLinkProtocolDiscriminator(LPD)correspondingtotheuseinthisTechnicalSpecificationshalltakethevalue"00",allothervaluesarereserved.NOTE:LPD="01"correspondstothedatalinkprotocolusedforSMSCB(seeGSM04.12).Bit87654321SpareLPDSAPIC/REA=1Figure4/GSM04.06:AddressfieldformatSIST EN 300 938 V8.0.1:2003
ETSIETSIEN300938V8.0.1(2000-09)15(GSM04.06version8.0.1Release1999)3.3Addressfieldvariables3.3.1Addressfieldextensionbit(EA)Theaddressfieldrangeisextendedbyreservingthefirsttransmittedbitoftheaddressfieldoctetstoindicatethefinaloctetoftheaddressfield.Thepresenceofa"1"inthefirstbitofanaddressfieldoctetsignalsthatitisthefinaloctetoftheaddressfield.Figure4showsthecasewherethefieldconsistsofoneoctet.3.3.2Command/responsefieldbit(C/R)TheC/Rbitidentifiesaframeaseitheracommandoraresponse.TheMSsideshallsendcommandswiththeC/Rbitsetto"0",andresponseswiththeC/Rbitsetto"1".TheBSsideshalldotheopposite;thatiscommandsaresentwithC/Rsetto"1",and
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