SIST ETS 300 938 E5:2003
(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 5.4.1 Release 1996)
- Abstract
CR SMG#31
- 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
SIST ETS 300 938 E5:2003 is the Slovenian adoption of ETS 300 938 Edition 5 for the GSM Mobile Station - Base Station System (MS-BSS) interface. It specifies the Data Link (DL) layer protocol, called LAPDm, for signalling and possible other applications between the Mobile Station (MS) and the Base Station System (BSS).
What does SIST ETS 300 938 E5:2003 specify?
SIST ETS 300 938 E5:2003 specifies the LAPDm frame structure, field formats, primitives, and procedures used on the Dm channel in GSM Phase 2+. It is the layer 2 data link specification that sits between layer 1 radio transmission and layer 3 signalling.
The document is organized into these main parts:
- Clause 0 - scope, normative references, and abbreviations
- Clause 1 - general principles and supported operating modes
- Clause 2 - peer-to-peer frame structure
- Clause 3 - field formats and protocol elements
- Clause 4 - layer-to-layer primitives and parameters
- Clause 5 - LAPDm procedures
- Clause 6 - special protocol operation for SAPI=0 and SAPI=3
- Annex A - random access procedures
- Annex G - handling of frames with parameter errors
- Annex H - document change history
| Annex | What it covers |
|---|---|
| A | Random access procedures and the format used for them |
| G | Handling of parameter errors in address, control, and length indicator fields |
| H | Document change history |
What are the key requirements of SIST ETS 300 938 E5:2003?
SIST ETS 300 938 E5:2003 defines two LAPDm operating modes: unacknowledged operation with UI frames, and acknowledged multiple-frame operation. That matters because some GSM control channels only need the simpler unacknowledged mode, while dedicated signalling channels can use full acknowledged transfer.
Clause 2 defines several frame formats. Format A carries no information field, formats B, Bter, B4, and Bbis carry information on different control channels, and Format C is used for random access in Annex A. The document also defines fill bits and transparency rules so bit streams can be transported without extra escaping.
Clause 3 defines the address field, control field, length indicator field, and the short L2 header type 1. The Service Access Point Identifier (SAPI) identifies which layer 3 entity the frame belongs to, while the C/R bit marks commands and responses depending on whether the MS or BSS sends them.
The control field in clause 3 uses I, S, and U formats. In practice this is the core of link behaviour: I frames carry numbered information, S frames handle acknowledgement and flow control, and U frames handle establishment, release, and unacknowledged information transfer.
Clause 4 defines the layer-to-layer primitives used between layer 2, layer 3, and the physical layer. The document includes DL-ESTABLISH, DL-RELEASE, DL-DATA, DL-UNITDATA, DL-SUSPEND, DL-RESUME, DL-RECONNECT, DL-RANDOMACCESS, MDL-ERROR, PH-DATA, PH-RANDOMACCESS, PH-CONNECT, PH-READY-TO-SEND, and PH-EMPTY-FRAME. These primitives matter because they describe what the implementation must signal to adjacent layers.
Clause 5 sets out the procedures for establishment, release, information transfer, retransmission, suspension and resumption, collision handling, and error recovery. It defines the timer T200, the retransmission limit N200, the window size k, and the frame size parameter N201. For implementation and test work, these are the rules that control when a frame is resent, when a link is released, and how segmentation is handled.
Clause 6 states the special operation for SAPI=0 and SAPI=3. For these SAPIs, acknowledged mode uses mandatory simplifications, including k=1 and special handling for link establishment, channel change, and busy handling.
What terms does SIST ETS 300 938 E5:2003 define?
- LAPDm - The GSM radio-interface data link protocol defined by this document for the Dm channel.
- SAPI - Service Access Point Identifier, which selects the layer 3 entity served by a data link.
- P/F bit - The Poll/Final bit, used to solicit a response in commands or mark the final response.
- N(S) - The send sequence number carried in I frames.
- N(R) - The receive sequence number used to acknowledge received I frames.
- T200 - The retransmission timer used for establishment, acknowledgement waiting, and recovery.
- UI - Unnumbered Information, the frame used for unacknowledged information transfer.
- SABM - Set Asynchronous Balanced Mode, the command used to establish multiple-frame operation.
Who uses SIST ETS 300 938 E5:2003?
SIST ETS 300 938 E5:2003 is used by GSM radio-access designers, base station and mobile station implementers, and protocol test engineers. It is also relevant to network integrators, conformance and interoperability laboratories, and quality teams checking that layer 2 behaviour matches the MS-BSS signalling rules.
What changed in SIST ETS 300 938 E5:2003 from the previous edition?
The foreword identifies this as the fifth edition and says the specification uses the versioning pattern 5.x.y, where x marks technical changes and y marks editorial changes. It also says annexes B to F were deleted from the original specification, while the annex numbering was kept for reference.
Which standards are used with SIST ETS 300 938 E5:2003?
| Reference | What it contributes |
|---|---|
| GSM01.04 | Abbreviations and acronyms used across GSM documents |
| GSM04.01 | General MS-BSS interface aspects and principles |
| GSM04.03 | Channel structures and access capabilities |
| GSM04.04 | Layer 1 general requirements |
| GSM04.05 | General aspects of the data link layer |
| GSM04.07 | General aspects of layer 3 signalling |
| GSM04.08 | Layer 3 specification for the mobile radio interface |
| GSM04.10 | Supplementary services signalling aspects |
| GSM04.12 | SMSCB support on the mobile radio interface |
| GSM05.02 | Multiplexing and multiple access on the radiopath |
| GSM08.56 | BSC-BTS layer 2 specification |
| GSM08.58 | BSC-BTS layer 3 specification |
| CCITT Recommendation Z.100 | SDL terminology used for timer handling |
What does the SIST ETS 300 938 E5:2003 document contain?
The document contains frame diagrams, bit-field mappings, and protocol tables for the LAPDm address, control, and length indicator fields. It also gives the command and response set, including I, RR, RNR, REJ, SABM, UA, DM, DISC, and UI, and shows how they are used in acknowledged and unacknowledged transfer.
It includes detailed procedures for establishment, release, retransmission, timer recovery, busy handling, segmentation, and channel-change support. Annex A gives the random access procedure format, while Annex G explains how to handle parameter errors in received frames.
The document also provides system parameter definitions and performance requirements, including T200, N200, N201, k, and the permitted response and repetition delays for specified channel types. These parts are the main basis for implementation, verification, and interoperability testing.
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Frequently Asked Questions
SIST ETS 300 938 E5:2003 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 5.4.1 Release 1996)". This standard covers: CR SMG#31
CR SMG#31
SIST ETS 300 938 E5:2003 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 ETS 300 938 E5:2003 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 5.4.1 Release 1996)33.070.50Globalni sistem za mobilno telekomunikacijo (GSM)Global System for Mobile Communication (GSM)ICS:Ta slovenski standard je istoveten z:ETS 300 938 Edition 5SIST ETS 300 938 E5:2003en01-december-2003SIST ETS 300 938 E5:2003SLOVENSKI
STANDARD
EUROPEANETS300938TELECOMMUNICATIONAugust2000STANDARDFifthEditionSource:SMGReference:RE/SMG-030406QR3ICS:33.020Keywords:Digitalcellulartelecommunicationssystem,GlobalSystemforMobilecommunications(GSM)GLOBALSYSTEMFORMOBILECOMMUNICATIONSRDigitalcellulartelecommunicationssystem(Phase2+);MobileStation-BaseStationSystem(MS-BSS)interface;DataLink(DL)layerspecification(GSM04.06version5.4.1Release1996)ETSIEuropeanTelecommunicationsStandardsInstituteETSISecretariatPostaladdress:F-06921SophiaAntipolisCEDEX-FRANCEOfficeaddress:650RoutedesLucioles-SophiaAntipolis-Valbonne-FRANCEInternet:secretariat@etsi.fr-http://www.etsi.orgTel.:+33492944200-Fax:+33493654716CopyrightNotification:Nopartmaybereproducedexceptasauthorizedbywrittenpermission.Thecopyrightandtheforegoingrestrictionextendtoreproductioninallmedia.©EuropeanTelecommunicationsStandardsInstitute2000.Allrightsreserved.SIST ETS 300 938 E5:2003
Page2ETS300938(GSM04.06version5.4.1Release1996):August2000Whilsteverycarehasbeentakeninthepreparationandpublicationofthepresentdocument,errorsincontent,typographicalorotherwise,mayoccur.Ifyouhavecommentsconcerningitsaccuracy,pleasewriteto"ETSIStandardsMakingSupportDept."attheaddressshownonthetitlepage.SIST ETS 300 938 E5:2003
Page3ETS300938(GSM04.06version5.4.1Release1996):August2000ContentsIntellectualPropertyRights.7Foreword.70Scope.90.1Normativereferences.90.2Abbreviations.91General.101.1Options.102Framestructureforpeer-to-peercommunication.112.1General.112.2Framedelimitationandfillbits.132.3Addressfield.142.4Controlfield.142.5Lengthindicatorfield.142.5aShortL2headertype1.142.6Informationfield.142.7Transparency.142.8Formatconvention.142.8.1Numberingconvention.142.8.2Orderofbittransmission.152.8.3Fieldmappingconvention.153ElementsofproceduresandformatsoffieldsforDataLinkLayerpeer-to-peercommunication.153.1General.153.2Addressfieldformat.163.3Addressfieldvariables.163.3.1Addressfieldextensionbit(EA).163.3.2Command/responsefieldbit(C/R).163.3.3Serviceaccesspointidentifier(SAPI).163.4Controlfieldformats.173.4.1Informationtransferformat-I.173.4.2Supervisoryformat-S.173.4.3Unnumberedformat-U.173.4aShortL2headertype1.183.5Controlfieldparametersandassociatedstatevariables.183.5.1Poll/Finalbit.183.5.2Multipleframeoperation-variablesandsequencenumbers.183.5.2.1Modulus.183.5.2.2SendstatevariableV(S).183.5.2.3AcknowledgestatevariableV(A).183.5.2.4SendsequencenumberN(S).193.5.2.5ReceivestatevariableV(R).193.5.2.6ReceivesequencenumberN(R).193.5.2.7Otherparametersandvariables.193.5.3Unacknowledgedoperationvariablesandparameters.193.6Lengthindicatorfieldformat.193.7Lengthindicatorfieldvariables.203.7.1Lengthindicatorfieldextensionbit(EL).203.7.2Moredatabit(M).203.7.3Lengthindicator(L).203.8Commandsandresponses.203.8.1Information(I)commands.203.8.2Setasynchronousbalancedmode(SABM)command.21SIST ETS 300 938 E5:2003
Page4ETS300938(GSM04.06version5.4.1Release1996):August20003.8.3Disconnect(DISC)command.223.8.4Unnumberedinformation(UI)command.223.8.5Receiveready(RR)command/response.223.8.6Reject(REJ)command/response.233.8.7Receivenotready(RNR)command/response.233.8.8Unnumberedacknowledgement(UA)response.233.8.9Disconnectedmode(DM)response.234Elementsforlayer-to-layercommunication.244.1Definitionofprimitivesandparameters.244.1.1Genericnames.244.1.1.1DL-ESTABLISH.244.1.1.2DL-RELEASE.244.1.1.3DL-DATA.244.1.1.4DL-UNITDATA.244.1.1.5DL-SUSPEND.244.1.1.6DL-RESUME.244.1.1.7DL-RECONNECT.254.1.1.8DL-RANDOMACCESS.254.1.1.9MDL-RELEASE.254.1.1.10MDL-ERROR.254.1.1.11PH-DATA.254.1.1.12PH-RANDOMACCESS.254.1.1.13PH-CONNECT.254.1.1.14PH-READY-TO-SEND.254.1.1.15PH-EMPTY-FRAME.254.1.2Primitivestypes.254.1.2.1REQUEST.254.1.2.2INDICATION.264.1.2.3RESPONSE.264.1.2.4CONFIRM.264.1.3Parameterdefinition.264.1.3.1Messageunit.264.1.3.2Channeltype.274.1.3.3ServiceAccessPoint.274.1.3.4Releasemode.274.1.3.5Errorcause.274.1.3.6Establishmode.274.1.3.7L2headertype.274.2Primitiveprocedures.315Definitionofthepeer-to-peerprotocolLAPDm.325.1General.325.2GeneralProtocolProcedures.335.2.1Unacknowledgedinformationtransfer.335.2.2Acknowledgedmultipleframeinformationtransfer.335.3Proceduresforunacknowledgedinformationtransfer.335.3.1General.335.3.2Transmissionofunacknowledgedinformation.335.3.3Receiptofunacknowledgedinformation.335.4Proceduresforestablishmentandreleaseofmultipleframeoperation.345.4.1Establishmentofmultipleframeoperation.345.4.1.1General.345.4.1.2Normalestablishmentprocedures.345.4.1.3ProcedureonexpiryoftimerT200:Normalestablishment355.4.1.4Contentionresolutionestablishmentprocedure.355.4.1.5ProcedureonexpiryoftimerT200:contentionresolution(MSonly).375.4.2Informationtransfer.375.4.2.1Generalrequirements.375.4.2.2Errorconditions.385.4.2.3Fillframes.395.4.3Suspensionandresumptionofmultipleframeoperation.39SIST ETS 300 938 E5:2003
Page5ETS300938(GSM04.06version5.4.1Release1996):August20005.4.3.1General.395.4.3.2Suspension.405.4.3.3Resumption.405.4.3.3.1Procedureafterchannelchange.405.4.3.3.2Procedureafterreturningtotheoldchannel(MSonly).415.4.4Terminationofmultipleframeoperation.425.4.4.1General.425.4.4.2Normalreleaseprocedure.425.4.4.3ProcedureonexpiryoftimerT200fornormalrelease.425.4.4.4Localendreleaseprocedure.435.4.5Idlestate.435.4.6Collisionofunnumberedcommandsandresponses.435.4.6.1Identicaltransmittedandreceivedcommands.435.4.6.2Differenttransmittedandreceivedcommands.445.4.6.3UnsolicitedDMresponseandSABMorDISCcommand.445.5Proceduresforinformationtransferinmultipleframeoperation.445.5.1TransmittingIframes.445.5.2ReceivingIframes.455.5.2.1PbitofthereceivedIframesetto"1".455.5.2.2PbitofthereceivedIframesetto"0".455.5.3Receivingacknowledgement.465.5.3.1OnreceiptofavalidIframe.465.5.3.2ReceivingsupervisorycommandframeswiththePbitsetto"1".465.5.4ReceivingREJframes.465.5.4.1ReceiptofavalidREJframe.465.5.4.2Transmittingframes.475.5.5ReceivingRNRframe.475.5.6Datalinklayerownreceiverbusycondition.495.5.7Waitingacknowledgement.495.6Abnormalreleaseandre-establishmentofmultipleframeoperation.505.6.1Criteriaforre-establishment.505.6.2Criteriaforabnormalrelease.505.6.3Proceduresforre-establishment.505.6.4Proceduresforabnormalrelease.505.7Exceptionconditionreportingandrecoveryformultipleframeoperation.515.7.1N(S)sequenceerror.515.7.2Timerrecovery.515.7.3Invalidframecondition.525.7.4N(R)sequenceerror.525.8Listofsystemparameters.525.8.1TimerT200.525.8.1.1ForSAPI=0andSAPI=3.525.8.1.2ForSAPIsotherthan0or3.535.8.2Maximumnumberofretransmissions(N200).535.8.2.1ForSAPI=0and3.535.8.2.2ForSAPIsotherthan0or3.535.8.3MaximumnumberofoctetsinanI,UI,SABMandUAframepartiallyorentirelyavailablefortheinformationfield(N201).535.8.4MaximumnumberofoutstandingIframes(k).535.8.5MaximumnumberofoctetsinaLayer3message.545.9Systemperformancerequirements.546SpecialprotocoloperationonSAPI=0andSAPI=3.55AnnexA(normative):Randomaccessprocedures.56A.1Descriptionoftheprocedure.56A.1.1ProcedureintheMS.56A.1.2ProcedureintheBS.56A.2Format.56SIST ETS 300 938 E5:2003
Page6ETS300938(GSM04.06version5.4.1Release1996):August2000AnnexG(normative):Handlingofframeswithparametererrorsintheaddress,controlandlengthindicatorfields.57G.1General.57G.2Parametererrorsintheaddressfield.57G.2.1UnallocatedSAPI.57G.2.2WrongvalueoftheC/Rbit.57G.2.3EAbitsetto"0".57G.3Parametererrorsinthecontrolfield.57G.3.1Supervisoryframes.57G.3.2Unnumberedframes.58G.4Parametererrorsinthelengthindicatorfield.58G.4.1ELbiterror.58G.4.2Informationframes.58G.4.3Supervisoryframes.58G.4.4DISCandDMframes.58G.4.5SABMUAandUIframes.58AnnexH(informative):Documentchangehistory.59History.60SIST ETS 300 938 E5:2003
Page7ETS300938(GSM04.06version5.4.1Release1996):August2000IntellectualPropertyRightsIPRsessentialorpotentiallyessentialtothepresentdocumentmayhavebeendeclaredtoETSI.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.ForewordThisEuropeanTelecommunicationStandard(ETS)hasbeenproducedbyETSITechnicalCommitteeSpecialMobileGroup(SMG).ThisETSdefinesthedatalinklayerprotocoloftheMobileStation-BaseStationSystem(MS-BSS)interfacewithinthedigitalcellulartelecommunicationssystem.ThecontentsofthepresentdocumentmaybesubjecttocontinuingworkwithinSMGandmaychangefollowingformalSMGapproval.ShouldSMGmodifythecontentsofthepresentdocumentitwillthenbere-submittedforformalapprovalproceduresbyETSIwithanidentifyingchangeofreleasedateandanincreaseinversionnumberasfollows:Version5.x.ywhere:5GSMPhase2+Release1996.xtheseconddigitisincrementedforchangesofsubstance,i.e.technicalenhancements,corrections,updates,etc.;ythethirddigitisincrementedwheneditorialonlychangeshavebeenincorporatedinthespecification.ThespecificationfromwhichthisETShasbeenderivedwasoriginallybasedonCEPTdocumentation,hencethepresentationofthisETSmaynotbeentirelyinaccordancewiththeETSIdraftingrules.AnnexesBtoFweredeletedfromtheoriginalspecification,however,forreferencingpurposestheannexnumberinghasbeenmaintained.TranspositiondatesDateofadoptionofthisETS:21July2000DateoflatestannouncementofthisETS(doa):31October2000DateoflatestpublicationofnewNationalStandardorendorsementofthisETS(dop/e):30April2001DateofwithdrawalofanyconflictingNationalStandard(dow):30April2001SIST ETS 300 938 E5:2003
Page8ETS300938(GSM04.06version5.4.1Release1996):August2000BlankpageSIST ETS 300 938 E5:2003
Page9ETS300938(GSM04.06version5.4.1Release1996):August20000ScopeThisEuropeanTelecommunicationStandard(ETS)definesadatalinklayerprotocoltobeusedforsignalling,andpossiblyalsoforotherapplications,ontheMS-BSinterface.0.1NormativereferencesThisETSincorporatesbydatedandundatedreference,provisionsfromotherpublications.Thesenormativereferencesarecitedattheappropriateplacesinthetextandthepublicationsarelistedhereafter.Fordatedreferences,subsequentamendmentstoorrevisionsofanyofthesepublicationsapplytothisETSonlywhenincorporatedinitbyamendmentorrevision.Forundatedreferences,thelatesteditionofthepublicationreferredtoapplies.[1]GSM01.04(ETR350):"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(ETS300936):"Digitalcellulartelecommunicationssystem;Layer1Generalrequirements".[5]GSM04.05(ETS300937):"Digitalcellulartelecommunicationssystem;DataLink(DL)layerGeneralaspects".[6]GSM04.07(ETS300939):"Digitalcellulartelecommunicationssystem(Phase2+);Mobileradiointerfacesignallinglayer3;Generalaspects".[7]GSM04.08(ETS300940):"Digitalcellulartelecommunicationssystem(Phase2+);Mobileradiointerfacelayer3specification".[8]GSM04.10(ETS300941):"Digitalcellulartelecommunicationssystem;Mobileradiointerfacelayer3Supplementaryservicesspecification;Generalaspects".[9]GSM04.12(ETS300943):"Digitalcellulartelecommunicationssystem(Phase2+);ShortMessageServiceCellBroadcast(SMSCB)supportonthemobileradiointerface".[10]GSM05.02(ETS300908):"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)".0.2AbbreviationsAbbreviationsusedinthisETSarelistedinGSM01.04.SIST ETS 300 938 E5:2003
Page10ETS300938(GSM04.06version5.4.1Release1996):August20001GeneralThisETSdescribestheframestructure,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.ThispartoftheETSisdescriptiveanddoesnotconstraintheimplementationoftherandomaccessfunction.TheprocedureisusedforCHANNELREQUESTontheRACHandHANDOVERACCESSonthemainDCCH.(AnnexesBtoFaredeleted).AnnexGgivesanoverviewofactionstakenonframescontainingparametererrors.1.1OptionsSupportofshortL2headertype1isanoptioninboththemobilestationandthenetwork;undercertainconditionsthesupportismandatory,asspecifiedinotherSpecifications.Alayer2protocolentitynotimplementingshortL2headertype1shalldiagnoseanE/AbiterrorandproceedasdefinedinannexG.2.3.SIST ETS 300 938 E5:2003
Page11ETS300938(GSM04.06version5.4.1Release1996):August20002Framestructureforpeer-to-peercommunication2.1GeneralAlldatalinklayerpeer-to-peerexchangesareinframesconformingtooneoftheformatsshowninfigure1.Severalformattypesareshowninthefigure:-FormatAisusedonDCCHsforframeswherethereisnoinformationfield.-FormatsB,BterandB4areusedonDCCHsforframescontaininganinformationfield:-formatBterisusedonrequestofhigherlayersifandonlyifshortL2headertype1issupportedandaUIcommandistobetransmittedonSAPI0;-formatB4isusedforUIframestransmittedbythenetworkonSACCH;-formatBisappliedinallothercases.-FormatBbisisusedonlyonBCCH,PCH,NCH,andAGCH.-InadditionthereisaFormatCfortransmissionofrandomaccesssignals.FormatCframesaredescribedinannexA.FormatA,B,Bbis,BterandB4framesaredescribedintheremainderofthisETS.Bit87654321OctetNo1:Addressfield:kControlfieldk+1k+2:Lengthindicatorfield:nn+1:Fillbits:N201+nFormattypeAFigure1/GSM04.06(sheet1of3):GeneralframeformatsSIST ETS 300 938 E5:2003
Page12ETS300938(GSM04.06version5.4.1Release1996):August2000Bit87654321OctetNo1:Addressfield:kControlfieldk+1k+2:Lengthindicatorfield:nn+1:Informationfield:NN+1:Fillbits:N201+nFormattypeBBit87654321OctetNo1:::Informationfield:::N201FormattypeBbisFigure1/GSM04.06(sheet2of3):GeneralframeformatsSIST ETS 300 938 E5:2003
Page13ETS300938(GSM04.06version5.4.1Release1996):August2000Bit87654321OctetNo1: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.SIST ETS 300 938 E5:2003
Page14ETS300938(GSM04.06version5.4.1Release1996):August2000Theendoftheusefulpartoftheframe,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.Theformatoftheaddressfieldisdefinedinsubclause3.2.2.4ControlfieldThecontrolfieldconsistsofoneoctet.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.SIST ETS 300 938 E5:2003
Page15ETS300938(GSM04.06version5.4.1Release1996):August2000Bit87654321Octetno12;;nFigure2/GSM04.06:Formatconvention2.8.2OrderofbittransmissionTheorderofbittransmissionisdefinedinGSM04.04.2.8.3FieldmappingconventionWhenafieldiscontainedwithinasingleoctet,thelowestbitnumberofthefieldrepresentsthelowestordervalue.Whenafieldspansmorethanoneoctet,theorderofbitvalueswithineachoctetprogressivelydecreasesastheoctetnumberincreases.Inthatpartofthefieldcontainedinagivenoctetthelowestbitnumberrepresentsthelowestordervalue.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.SIST ETS 300 938 E5:2003
Page16ETS300938(GSM04.06version5.4.1Release1996):August20003.2AddressfieldformatThefieldconsistsof:-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:Addressfieldformat3.3Addressfieldvariables3.3.1Addressfieldextensionbit(EA)Theaddressfieldrangeisextendedbyreservingthefirsttransmittedbitoftheaddressfieldoctetstoindicatethefinaloctetoftheaddressfield.Thepresenceofa"1"inthefirstbitofanaddressfieldoctetsignalsthatitisthefinaloctetoftheaddressfield.Figure4showsthecasewherethefieldconsistsofoneoctet.3.3.2Command/responsefieldbit(C/R)TheC/Rbitidentifiesaframeaseitheracommandoraresponse.TheMSsideshallsendcommandswiththeC/Rbitsetto"0",andresponseswiththeC/Rbitsetto"1".TheBSsideshalldotheopposite;thatiscommandsaresentwithC/Rsetto"1",andresponsesaresentwithC/Rsetto"0".ThecombinationsfortheBSsideandMSsideareshownintable1.Table1/GSM04.06:C/RfieldbitusageTypeDirectionC/RvalueCommandBSsidetoMSside1MSsidetoBSside0ResponseBSsidetoMSside0MSsidetoBSside13.3.3Serviceaccesspointidentifier(SAPI)Theserviceaccesspointidentifier(SAPI)identifiesapointatwhichdatalinklayerservicesareprovidedbythedatalinklayertoalayer3entity(seeGSM04.05).TheSAPIallows8serviceaccesspointstobespecifiedinitially,wherebit3oftheaddressfieldoctetcontainingtheSAPIistheleastsignificantbinarydigitandbit5isthemostsignificant.TheSAPIvaluesareallocatedasshownintable2.SIST ETS 300 938 E5:2003
Page17ETS300938(GSM04.06version5.4.1Release1996):August2000Table2/GSM04.06:AllocationofSAPIvaluesSAPIvalueRelatedentity0Callcontrolsignalling,mobilitymanagementsignallingandradioresourcemanagementsignalling(seeGSM04.08and04.10)3ShortmessageserviceAllothersReservedforfuturestandardization3.4ControlfieldformatsThecontrolfieldidentifiesthetypeofframe,whichwillbeeitheracommandoraresponse.Thecontrolfieldwillcontainsequencenumbers,whereapplicable.Threetypesofcontrolfieldformatsarespecified:numberedinformationtransfer(Iformat),supervisoryfunctions(Sformat),andunnumberedinformationtransferandcontrolfunctions(Uformat).ThecontrolfieldformatsforLAPDmareshownintable3.3.4.1Informationtransferformat-ITheIformatshallbeusedtoperformaninformationtransferbetweenlayer3entities.ThefunctionsofN(S),N(R)andP(definedin3.5)areindependent;thatis,eachIframehasanN(S)sequencenumber,anN(R)sequencenumberwhichmayormaynotacknowledgeadditionalIframesreceivedbythedatalinklayerentity,andaPbitthatmaybesetto"0"or"1".TheuseofN(S),N(R)andPisdefinedinclause5.3.4.2Supervisoryformat-STheSformatshallbeusedtoperformdatalinksupervisorycontrolfunctionssuchas:acknowledgeIframes,requestretransmissionofIframes,andrequestatemporarysuspensionoftransmissionofIframes.ThefunctionsofN(R)andP/Fareindependent;thatis,eachsupervisoryframehasanN(R)sequencenumberwhichmayormaynotacknowledgeadditionalIframesreceivedbythedatalinklayerentity,andaP/Fbitthatmaybesetto"0"or"1".TheuseofN(R)andtheP/Fbitisdescribedinclause5.3.4.3Unnumberedformat-UTheUformatshallbeusedtoprovideadditionaldatalinkcontrolfunctionsandunacknowledgedinformationtransfer.Thisformatdoesnotcontainsequencenumbers.ItdoesincludeaP/Fbitthatmaybesetto"0"or"1".Table3/GSM04.06:ControlfieldformatControlfieldbits87654321IformatN(R)PN(S)0SformatN(R)P/FSS01UformatUUUP/FUU11N(S)Transmittersendsequencenumber.N(R)Transmitterreceivesequencenumber.SSupervisoryfunctionbit.UUnnumberedfunctionbit.P/FPollbit,whenissuedasacommand,finalbit,whenissuedasaresponse.Fordefinitionofvaluesforsupervisoryfunctionbitsandunnumberedfunctionbits,seetable4.SIST ETS 300 938 E5:2003
Page18ETS300938(GSM04.06version5.4.1Release1996):August20003.4aShortL2headertype1TheshortL2headertype1fieldisusedinformatBterframes,seesubclause2.1.Itconsistsof2bits,bothshalltakevalue0.NOTE:IntroductionoffurthershortL2headertypes(longerthan2bits,settingbit2to"1"andbit1to"0")isforfurtherstudy.TheshortL2headertype1implicitlydefinesaUIcommandframebelongingtoSAPI=0,withlengthN201.AllotherparametersofaL2frameheaderareirrelevant.3.5ControlfieldparametersandassociatedstatevariablesThevariousparametersassociatedwiththecontrolfieldformatsaredescribedinthisclause.Thecodingofthebitswithintheseparametersissuchthatthelowestnumberedbitwithintheparameterfieldistheleastsignificantbit.3.5.1Poll/FinalbitAllframescontainP/F,thePoll/Finalbit.ThePoll/Final(P/F)bitservesafunctioninbothcommandframesandresponseframes.IncommandframestheP/FbitisreferredtoasthePbit.InresponseframesitisreferredtoastheFbit.ThePbitsetto"1"isusedbyadatalinklayerentitytocreate(poll)aresponseframefromthepeerdatalinklayerentity.TheFbitsetto"1"isusedbyadatalinklayerentitytoindicatetheresponseframetransmittedasaresultofasoliciting(poll)command.TheuseoftheP/Fbitisdescribedinclause5.3.5.2Multipleframeoperation-variablesandsequencenumbers3.5.2.1ModulusEachIframeissequentiallynumberedbyasequencenumberwhichmayhavethevalue0through7.Arithmeticsactingonvariableswhicharerelatedtosuchsequencenumbers(i.e.N(S),N(R),V(S),V(R),V(A);seefollowingsubclauses)operatemodulo8.NOTE:Modulo8operationonnegativenumbersisperformedbyaddingmultiplesof8tothenegativenumberuntiltheresultbecomesnonnegative.Thencommonmodulo8operationisapplied.3.5.2.2SendstatevariableV(S)Eachpoint-to-pointdatalinkconnectionendpointshallhaveanassociatedsendstatevariable(V(S))whenusingIframecommands.Thesendstatevariabledenotesthesequencenumberofthenextin-sequenceIframetobetransmitted.Thesendstatevariablecantakeonthevalue0through7.Thevalueofthesendstatevariableshallbeincrementedby1witheachsuccessiveIframetransmission,andshallnotexceedV(A)bymorethanthemaximumnumberofoutstandingIframesk(Thewindowsizekisdefinedinsubclause5.8.4).Thevalueofkmaybeintherangeof1=
Page19ETS300938(GSM04.06version5.4.1Release1996):August2000Theacknowledgestatevariableidentifiesthelastframethathasbeenacknowledgedbyitspeer(V(A)-1equalstheN(S)ofthelastacknowledgedIframe).Theacknowledgestatevariablecantakeonthevalue0through7.ThevalueoftheacknowledgestatevariableshallbeupdatedbythevalidN(R)valuesreceivedfromitspeer(seesubclause3.5.2.6).AvalidN(R)valueisonethatisintherangeV(A)=
Page20ETS300938(GSM04.06version5.4.1Release1996):August20003.7Lengthindicatorfieldvariables3.7.1Lengthindicatorfieldextensionbit(EL)Thelengthindicatorfieldisextendedbyreservingthefirsttransmittedbitofthelengthindicatorfieldoctetstoindicatethefinaloctetofthefield.Presenceofa"1"inthefirstbitofalengthindicatorfieldoctetsignalsthatitisthefinaloctetofthefield.Figure5showsthecasewherethefieldconsistsofoneoctet.3.7.2Moredatabit(M)Themoredatabit,M,isusedtoindicatesegmentationoflayer3messageunitsondatalinklayerframes.Layer3messages,whichneedtobesegmented,shallonlybetransportedbyI-frames.WhentheMbitissetto"1",itindicatesthattheinformationfieldoftheframecontainsonlyasegmentofthelayer3messageunit.TheMbitsetto"0"indicates:i)thattheinformationfieldcontainsacompletelayer3messageunitprovidedthattheMbitofthepreviousframewassetto"0";ii)thattheinformationfieldcontainsthelastsegmentofalayer3messageunitiftheMbitofthepreviousframewassetto"1".WhentheMbitissetto"1",theinformationfieldshallcontainthemaximumnumberofoctets,N201,thataninformationframecancontain,seesubclause5.8.3forthevalueofN201.Inframesotherthaninformation(I)framestheMbitshallbesetto"0".3.7.3Lengthindicator(L)Thelengthindicatorconsistsof6bitsandisusedtoindicatethenumberofoctetscontainedintheinformationfieldofUI,SABM,UAorIframes,ieanyvaluefrom0toN201inclusive.TheL=0shallbeusedinframesnotcontaininganinformationfield.3.8CommandsandresponsesThefollowingcommandsandresponsesareusedbyeithertheMSortheBSdatalinklayerentitiesandarerepresentedintable4.Eachdatalinkconnectionsupportstheappropriatesetofcommandsandresponsesforthetypeofoperationdesired(seeclause5).ForpurposesoftheLAPDmprocedures,frameswiththesupe
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