ETSI EN 300 912 V8.3.1 (2000-10)

Digital cellular telecommunications system (Phase 2+) (GSM); Radio subsystem synchronization (GSM 05.10 version 8.3.1 Release 1999)

REN/SMG-020510Q8R1

Digitalni celični telekomunikacijski sistem (faza 2+) – Sinhronizacija radijskega podsistema (GSM 05.10, različica 8.3.1, izdaja 1999)

General Information

• Status: Published
• Publication Date: 16-Oct-2000
• Technical Committee: SMG 2 - Radio
• Current Stage: 12 - Completion
• Due Date: 06-Oct-2000
• Completion Date: 17-Oct-2000
• Ref Project: SIST EN 300 912 V8.3.1:2003 - Digital cellular telecommunications system (Phase 2+) (GSM); Radio subsystem synchronization (GSM 05.10 version 8.3.1 Release 1999)

Standards Content (Sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Digital cellular telecommunications system (Phase 2+) (GSM); Radio subsystem synchronization (GSM 05.10 version 8.3.1 Release 1999)33.070.50Globalni sistem za mobilno telekomunikacijo (GSM)Global System for Mobile Communication (GSM)ICS:Ta slovenski standard je istoveten z:EN 300 912 Version 8.3.1SIST EN 300 912 V8.3.1:2003en01-december-2003SIST EN 300 912 V8.3.1:2003SLOVENSKI
STANDARD



SIST EN 300 912 V8.3.1:2003



ETSIEN300912V8.3.1(2000-10)EuropeanStandard(Telecommunicationsseries)Digitalcellulartelecommunicationssystem(Phase2+);Radiosubsystemsynchronization(GSM05.10version8.3.1Release1999)GLOBALSYSTEMFORMOBILECOMMUNICATIONSRSIST EN 300 912 V8.3.1:2003



ETSIETSIEN300912V8.3.1(2000-10)2(GSM05.10version8.3.1Release1999)ReferenceREN/SMG-020510Q8R1KeywordsDigitalcellulartelecommunicationssystem,GlobalSystemforMobilecommunications(GSM)ETSI650RoutedesLuciolesF-06921SophiaAntipolisCedex-FRANCETel.:[phone]Fax:[phone]SiretN°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:[e-mail]opartmaybereproducedexceptasauthorizedbywrittenpermission.Thecopyrightandtheforegoingrestrictionextendtoreproductioninallmedia.©EuropeanTelecommunicationsStandardsInstitute2000.Allrightsreserved.SIST EN 300 912 V8.3.1:2003



ETSIETSIEN300912V8.3.1(2000-10)3(GSM05.10version8.3.1Release1999)ContentsIntellectualPropertyRights.5Foreword.51Scope.61.1References.61.2Definitionsandabbreviations.72Generaldescriptionofsynchronizationsystem.73Timebasecounters.83.1Timingstateofthesignals.83.2Relationshipbetweencounters.84Timingoftransmittedsignals.95BTSRequirementsforSynchronization.95.1Frequencysource.95.2Timebasecounters.105.3InternalBTScarriertiming.105.4InitialTimingadvanceestimation.105.5Maximumtimingadvancevalue.105.6Delaytracking.105.6.1Forcircuitswitchedchannels.105.6.2Forpacketswitchedchannels.105.6.3Delayassessmenterror.115.6.4Pico-BTSdelaytracking.115.7Timeslotlength.115.8RangeofTimingadvance.116MSRequirementsforSynchronization.116.1MScarrierfrequency.126.2Internaltimebase.126.3AssessmentofBTStiming.126.4Timingoftransmission.126.5ApplicationofTimingAdvance.126.5.1Forcircuitswitchedchannels.126.5.2Forpacketswitchedchannels.126.6AccesstoanewBTS.136.7Temporarylossofsignal.146.8Timingofintracellchannelchange.146.9ApplicationofnewTimingAdvancevalue.146.10Definitionof"readytotransmitwithinxms".146.11DefinitionofadditionalreactiontimesforGPRSmobilestations.146.11.1Uplinkanddownlinkassignmentreactiontimes.146.11.2Changeinchannelcodingschemecommandedbynetwork.146.11.3Contentionresolutionreactiontime.156.11.4Reactiontimeinresponsetoothercommandingmessages.156.12ObservedFrequencyOffset(OFO)reportedbytheCTS-MS.157CTS-FPRequirementsforSynchronization.157.1Frequencysourcedefaultrequirements.157.2FrequencysourceforaCTS-FPassistedbyaCTS-MS.157.3InternalCTS-FPcarriertiming.157.4Timeslotlength.157.5AssessmentofCTS-MSdelay.16SIST EN 300 912 V8.3.1:2003



ETSIETSIEN300912V8.3.1(2000-10)4(GSM05.10version8.3.1Release1999)AnnexA(normative):Additionalrequirementsforpseudo-synchronization,synchronizedhandoversandpseudo-synchronizedhandovers.17A.1Generaldescriptionsanddefinitions.17A.1.1Conventions.17A.1.2Definitions.17A.1.3Detailsofoperations.17A.2BTSrequirements.18A.2.1Thepseudo-synchronizationscheme.18A.2.1.1BTSatimedifferenceestimate.18A.2.1.2Thereceptionepochcriterion.18A.2.1.3Pseudo-synchronizedhandover.18A.2.2Thesynchronizationrequirement.18A.3MSrequirements.19A.3.1Provisionoftimedifferenceinformation.19A.3.2Aftereachsuccessfulhandover.19A.3.3Synchronizedorapseudosynchronizedhandover.19AnnexB(informative):CTSBCHtimeslotshiftingpropertiesforCTS-MSsynchronization.20B.1DeterminationofTNbytheCTS-MSwhenCTSBCHshiftingisnotactive.20B.2DeterminationofTNbytheCTS-MSwhenCTSBCHshiftingisactive.20AnnexC(informative):BTSfrequencysourcestabilityandE-OTDLMUreportingperiodsforLCS.21C.1BTSfrequencysourcestabilityandE-OTDLMUreportingperiods.21C.2Frequencysourcestability.21C.3RelationshiptoE-OTDreportingperiods.21AnnexD(informative):Changecontrolhistory.23History.24SIST EN 300 912 V8.3.1:2003



ETSIETSIEN300912V8.3.1(2000-10)5(GSM05.10version8.3.1Release1999)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).ThepresentdocumentdefinestherequirementsforsynchronizationontheGSMradiosub-systemofthedigitalmobilecellularandpersonalcommunicationsystemsoperatinginthe900MHzand1800MHzband(GSM900andDCS1800).ThecontentsofthepresentdocumentmaybesubjecttocontinuingworkwithinSMGandmaychangefollowingformalSMGapproval.ShouldSMGmodifythecontentsofthepresentdocumentitwillthenbere-submittedforformalapprovalproceduresbyETSIwithanidentifyingchangeofreleasedateandanincreaseinversionnumberasfollows:Version8.x.ywhere:8GSMPhase2+Release1999.xtheseconddigitisincrementedforchangesofsubstance,i.e.technicalenhancements,corrections,updates,etc.;ythethirddigitisincrementedwheneditorialonlychangeshavebeenincorporatedinthespecification.NationaltranspositiondatesDateofadoptionofthisEN:29September2000DateoflatestannouncementofthisEN(doa):31December2000DateoflatestpublicationofnewNationalStandardorendorsementofthisEN(dop/e):30June2001DateofwithdrawalofanyconflictingNationalStandard(dow):30June2001SIST EN 300 912 V8.3.1:2003



ETSIETSIEN300912V8.3.1(2000-10)6(GSM05.10version8.3.1Release1999)1ScopeThepresentdocumentdefinestherequirementsforsynchronizationontheradiosub-systemofthedigitalcellulartelecommunicationssystemsGSM.However,itdoesnotdefinethesynchronizationalgorithmstobeusedintheBaseTransceiverStation(BTS),CTSFixedPart(CTS-FP)andMobileStation(MS).Theseareuptothemanufacturertospecify.1.1ReferencesThefollowingdocumentscontainprovisionswhich,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]GSM03.60:"Digitalcellulartelecommunicationssystem(Phase2+);GeneralPacketRadioService(GPRS);ServiceDescriptionStage2".[3]GSM03.64:"Digitalcellulartelecommunicationssystem(Phase2+);GeneralPacketRadioService(GPRS);GPRSRadioInterfaceStage2".[4]GSM04.08:"Digitalcellulartelecommunicationssystem(Phase2+);Mobileradiointerfacelayer3specification".[5]GSM04.60:"Digitalcellulartelecommunicationssystem(Phase2+);GeneralPacketRadioService(GPRS);MobileStation(MS)-BaseStationSystem(BSSinterface;RadioLinkControl(RLC)andMediumAccessControl(MAC)LayerSpecification".[6]GSM05.02:"Digitalcellulartelecommunicationssystem(Phase2+);Multiplexingandmultipleaccessontheradiopath".[7]GSM05.05:"Digitalcellulartelecommunicationssystem(Phase2+);Radiotransmissionandreception".[8]GSM05.08:"Digitalcellulartelecommunicationssystem(Phase2+);Radiosubsystemlinkcontrol".[9]GSM03.30:"Digitalcellulartelecommunicationssystem(Phase2+);Radionetworkplanningaspects".[10]GSM03.52:"Digitalcellulartelecommunicationssystem(Phase2+);GSMCordlessTelephonySystem(CTS),Phase1;LowerlayersoftheCTSRadioInterface;Stage2".[11]GSM05.56:"Digitalcellulartelecommunicationssystem(Phase2+);GSMCordlessTelephonySystem(CTS),Phase1;CTS-FPRadiosubsystem".SIST EN 300 912 V8.3.1:2003



ETSIETSIEN300912V8.3.1(2000-10)7(GSM05.10version8.3.1Release1999)1.2DefinitionsandabbreviationsInadditiontothosebelow,abbreviationsusedinthepresentdocumentarelistedinGSM01.04.Forthepurposesofthepresentdocument,thefollowingtermsanddefinitionsapply:BTS:BaseTransceiverStation.CTS-FP:CTSFixedPart.CTS-MS:MSoperatinginCTSmode.TimingAdvance:signalsentbytheBTStotheMSwhichtheMSusestoadvanceitstimingsoftransmissionstotheBTSsoastocompensateforpropagationdelay.Quartersymbolnumber:timingofquartersymbolperiods(12/13µs)withinatimeslot.Symbolperiodcanbe1or3bitperiodsdependinguponmodulation.Timeslotnumber:timingoftimeslotswithinaTDMAframe.TDMAframenumber:countofTDMAframesrelativetoanarbitrarystartpoint.CurrentServingBTS:BTSononeofwhosechannels(TCH,DCCH,CCCHorPDCH)theMSiscurrentlyoperating.CurrentServingCTS-FP:CTS-FPononeofwhosechannels(TCHorCTScontrolchannels)theCTS-MSiscurrentlyoperating.Timebasecounters:setofcounterswhichdeterminethetimingstateofsignalstransmittedbyaBTSorMS.MStimingoffset:delayofthereceivedsignalrelativetotheexpectedsignalfromanMSatzerodistanceunderstaticchannelconditionswithzerotimingadvance.Thisisaccurateto±1symbol,andreportedonceperSACCHorafteraRACHas.required(i.e.atthesamerateastimingadvance).Forexample,foranMSwitharoundtrippropagationdelayofPsymbols,butwithatimingadvanceofTsymbols,thereportedtimingoffsetwillbeP-Tquantizedtothenearestsymbol.ForGPRStheMStimingoffsetisnotreported.TimingAdvanceIndex:TimingAdvanceIndexTAIusedforGPRS,whichdeterminesthepositionofthesubchannelonPTCCH(seeGSM05.02)usedbytheMStosendanaccessburst,fromwhichthenetworkcanderivethetimingadvance.ObservedFrequencyOffset(OFO):differenceoffrequencyofsignalsreceivedbyaCTS-MSfromaCTS-FPandaBTS.TheObservedFrequencyOffsetismeasuredandreportedbytheCTS-MSonCTS-FPrequirement.TheObservedFrequencyOffsetisexpressedinppmwithanaccuracyof1/64ppm(i.e.about0,016ppm).Timegroup(TG):usedforcompact,timegroupsshallbenumberedfrom0to3andaparticulartimegroupshallbereferredtobyitstimegroupnumber(TG)(seeGSM05.02).2GeneraldescriptionofsynchronizationsystemThisclausegivesageneraldescriptionofthesynchronizationsystem.Detailedrequirementsaregiveninclauses3to7.TheBTSsendssignalsontheBCCHor,forCOMPACTontheCPBCCH,toenabletheMStosynchronizeitselftotheBTSandifnecessarycorrectitsfrequencystandardtobeinlinewiththatoftheBTS.ThesignalssentbytheBTSforthesepurposesare:a)Frequencycorrectionbursts;b)Synchronizationbursts.Thetimingsoftimeslots,TDMAframes,TCHframes,controlchannelframes,and(forCOMPACT)therotationoftimegroupsareallrelatedtoacommonsetofcounterswhichruncontinuouslywhethertheMSandBTSaretransmittingornot.Thus,oncetheMShasdeterminedthecorrectsettingofthesecounters,allitsprocessesaresynchronizedtothecurrentservingBTS.SIST EN 300 912 V8.3.1:2003



ETSIETSIEN300912V8.3.1(2000-10)8(GSM05.10version8.3.1Release1999)TheMStimesitstransmissionstotheBTSinlinewiththosereceivedfromtheBTS.TheBTSsendstoeachMSa"timingadvance"parameter(TA)accordingtotheperceivedroundtrippropagationdelayBTS-MS-BTS.TheMSadvancesitstimingbythisamount,withtheresultthatsignalsfromdifferentMS'sarrivingattheBTSandcompensatedforpropagationdelay.Thisprocessiscalled"adaptiveframealignment".Additionally,synchronizationfunctionsmaybeimplementedinboththeMSandtheBTStosupporttheso-calledpseudosynchronizationscheme.ThesupportofthisschemeisoptionalexceptthatMSshallmeasureandreporttheObservedTimingDifference(OTD),whichisamandatoryrequirement.Thedetailedspecificationsofthepseudo-synchronizationschemeareincludedinannexA.InCTS,theCTS-FPsendssignalsontheCTSBCHtoenabletheMStosynchronizeitselftotheCTS-FPandifnecessarycorrectitsfrequencystandardtobeinlinewiththatoftheCTS-FP.ThesignalssentbytheCTS-FPforthesepurposesare:a)Frequencycorrectionbursts;b)Synchronizationbursts.Thetimingsoftimeslots,TDMAframes,CTSBCH,CTSARCH,CTSAGCHandCTSPCHframesareallrelatedtoafirstcommonsetofcounterswhichruncontinuouslywhethertheCTS-MSandCTS-FParetransmittingornot.Thus,oncetheCTS-MShasdeterminedthecorrectsettingofthesefirstcounters,theCTS-MSisabletoattachtothecurrentservingCTS-FP.Inaddition,duringCTS-MSattachment,theCTS-FPsendstotheCTS-MStheremainingcountersforSACCHandTCHframes.Then,allprocessesoftheCTS-MSaresynchronizedtothecurrentservingCTS-FP.TheCTS-MStimesitstransmissionstotheCTS-FPinlinewiththosereceivedfromtheCTS-FP.ThetimingadvanceparameterissettozeroforCTS.Additionally,theCTS-FPmaybeassistedbyaCTS-MStoadjustitsfrequencysource.WhenrequiredbytheCTS-FP,theCTS-MSestimatesifpossibleandreportstheObservedFrequencyOffsetoftheCTS-FPwithaspecifiedBTS.TheCTS-FPmaythenadjustitsfrequencysourceaccordingtothisvalue.3Timebasecounters3.1TimingstateofthesignalsThetimingstateofthesignalstransmittedbyaBTS,aMS,aCTS-FP,oranCompactBTSandMSisdefinedbythefollowingcounters:-QuartersymbolnumberQN(0-624)-SymbolnumberBN(0-156);-TimeslotnumberTN(0-7);-TDMAframenumberFN(0to(26x51x2048)-1=2715647);or-foranonattachedCTS-MS,TDMAframenumbermodulo52T4(0-51);or-forCompact,TDMAframenumberFN(0to(52x51x1024)-1=2715647).InCTS,theCTS-MSshallmanagedifferentsetsofcountersforCTSoperationandGSMoperation.3.2RelationshipbetweencountersTherelationshipbetweenthesecountersisasfollows:-QNincrementsevery12/13µs;-BN=IntegerpartofQN/4;-TNincrementswheneverQNchangesfromcount624to0;-FNincrementswheneverTNchangesfromcount7to0;orSIST EN 300 912 V8.3.1:2003



ETSIETSIEN300912V8.3.1(2000-10)9(GSM05.10version8.3.1Release1999)-foraCTS-MS,T4incrementswheneverTNchangesfromcount7to0.4TimingoftransmittedsignalsThetimingofsignalstransmittedbytheMS,BTSandCTS-FParedefinedinGSM05.02.TheMScanusethetimingofreceiptofthesynchronizationbursttosetupitstimebasecountersasfollows:QNissetbythetimingofthetrainingsequence;TN=0whenthesynchburstisreceived;FN=51((T3-T2)mod(26))+T3+51x26xT1whenthesynchburstisreceived,(whereT3=(10xT3')+1,T1,T2andT3'beingcontainedininformationfieldsinsynchronizationburst).ForCompact,theMScanusethetimingofreceiptofthesynchronizationbursttosetupitstimebasecountersasfollows:QNissetbythetimingofthetrainingsequence;FN=(R1x51+R2)x52+51whenthesynchburstisreceived(whereR1andR2arecontainedininformationfieldsinsynchronizationburst);TNisdeterminedfromTGasdescribedinGSM05.02,whereTGiscontainedininformationfieldsinsynchronizationburst.ForCTS,thetimebasecountersaresetasfollows:QNissetbythetimingofthetrainingsequence;TNissetaccordingtotheCTSBCH-SBposition(seeAnnexC);T4=51whentheCTSBCH-SBisreceived(priortoattachment);FN=(51((T3-T2)mod(26))+T3+51x26xT1)mod(2715648)whentheCTS-MSreceivesthelastCTSAGCHburstofthenon-hoppingaccessprocedure,whereT2=T4mod(26),andT1andT3beingcontainedinthisCTSimmediateassignmentmessage.Thereafter,thetimebasecountersareincrementedasinclause3.2.(WhenadjacentBTS'sarebeingmonitoredforhandoverpurposes,orforcellreselectionpurposesingroupreceivemode,theMSmaychoosetostorethevaluesofQN,TNandFNforalltheBTS'swhosesynchronizationburstshavebeendetectedrelativetoQN,TNandFNforitscurrentservingBTS).5BTSRequirementsforSynchronizationTheconditionsunderwhichtherequirementsofclauses5.4and5.6mustbemetshallbe3dBbelowthereferencesensitivitylevelorinputlevelforreferenceperformance,whicheverapplicable,inGSM05.05and3dBlesscarriertointerferenceratiothanthereferenceinterferenceratiosinGSM05.05.5.1FrequencysourceTheBTSshalluseasinglefrequencysourceofabsoluteaccuracybetterthan0.05ppmforbothRFfrequencygenerationandclockingthetimebase.ThesamesourceshallbeusedforallcarriersoftheBTS.ForthepicoBTSclasstheabsoluteaccuracyrequirementisrelaxedto0.1ppm.NOTE:BTSfrequencysourcestabilityisonefactorrelatingtoE-OTDLCSperformanceandthereaderisreferredtoAnnexCfortherelationshipbetweenBTSfrequencysourcestabilityandE-OTDLCSperformancecharacteristics.SIST EN 300 912 V8.3.1:2003



ETSIETSIEN300912V8.3.1(2000-10)10(GSM05.10version8.3.1Release1999)5.2TimebasecountersItisoptionalwhetherthetimebasecountersofdifferentBTS'saresynchronizedtogether.ForCOMPACTinterbasestationtimesynchronizationisrequiredsuchthattimeslotnumber(TN)=i(i=0to7)andframenumber(FN)withFNmod208=0shalloccuratthesametimeinallcells.ThetimebasecountersofdifferentBTSsshallbesynchronizedtogethersuchthatthetimingdifferencebetweendifferentBTSsshallbelessthan1symbolperiod,48/13µs(whichcanbe1or3bitsdependinguponmodulation)measuredattheBTSantenna.IfacelldefinesaCOMPACTcellinitsneighborlist,timesynchronizationisrequiredsuchthattimeslotnumber(TN)=i(i=0to7)andframenumber(FN)withFNmod208=0shalloccuratthesametimeinbothcells.5.3InternalBTScarriertimingThechannelsofdifferentcarrierstransmittedbyaBTSshallbesynchronizedtogether,i.e.controlledbythesamesetofcounters.Thetimingdifferencebetweenthedifferentcarriersshallbelessthan1/4symbolperiods,measuredattheBTSantenna.Forpico-BTS,thetimingdifferencebetweendifferentcarriersshallbelessthan2symbolperiods,measuredattheBTSantenna.5.4InitialTimingadvanceestimationWhentheBTSdetectsanaccessbursttransmissiononRACHorPRACH,itshallmeasurethedelayofthissignalrelativetotheexpectedsignalfromanMSatzerodistanceunderstaticchannelconditions.Thisdelay,calledthetimingadvance,shallberoundedtothenearestsymbolperiodandincludedinaresponsefromtheBTSwhenapplicable.Forthepico-BTSthereisnorequirementtomeasurethistimingadvance.However,eitherthismeasuredvalueoraprogrammablevalueoftimingadvanceshallbeincludedintheresponsefromtheBTSwhenatimingadvancevalueneedstobesent.5.5MaximumtimingadvancevalueThemaximumtimingadvancevalueTAmaxshallbe63.IftheBTSmeasuresavaluelargerthanthis,itshallsetthetimingadvanceto63.InthecaseofGSM400theextendedtimingadvanceinformationelementissupportedandthemaximumtimingadvancevalueTAmaxshallbe219.IftheBTSmeasuresavaluelargerthanthis,itshallsetthetimingadvanceto219.(GSM03.30defineshowthePLMNdealswithMS'swherethedelayexceedstimingadvancevalue63).5.6Delaytracking5.6.1ForcircuitswitchedchannelsTheBTSshallthereaftercontinuouslymonitorthedelayofthenormalburstssentbyfromtheMS.Ifthedelaychangesbymorethanonesymbolperiod,thetimingadvanceshallbeadvancedorretarded1andthenewvaluesignalledtotheMS.Restrictingthechangeintimingadvanceto1symbolperiodatatimegivesthesimplestimplementationoftheBTS.HowevertheBTSmayusealargerchangethanthisbutgreatcaremustthenbeusedintheBTSdesign.5.6.2ForpacketswitchedchannelsTheBTSshallperformthecontinuousupdatetimingadvancemechanismforallMSworkinginpackettransfermodeforwhichanPTCCHsubchannelisassigned,exceptforMSclassAindedicatedmode.ThereforetheBTSshallmonitorthedelayoftheaccessburstssentbytheMSonPTCCHandrespondwithtimingadvancevaluesforallMSperformingtheprocedureonthatPDCH.ThesetimingadvancevaluesshallbesentviaadownlinksignallingmessageonPTCCH.SIST EN 300 912 V8.3.1:2003



ETSIETSIEN300912V8.3.1(2000-10)11(GSM05.10version8.3.1Release1999)TheBTSshallupdatethetimingadvancevaluesinthenextdownlinksignallingmessagefollowingtheaccessburst.TheBTSmayalsomonitorthedelayofthenormalburstsandaccessburstssentbytheMSonPDTCHandPACCH.WheneveranupdatingofTAisneeded,theBTSmaysendthenewTAvalueinapowercontrol/timingadvancemessage(seeGSM04.60).ForMSclassAindedicatedmodetheBTSshallfollowtheproceduredescribedinclause5.6.1.5.6.3DelayassessmenterrorForcircuitandpackedswitchedchannelsthedelayshallbeassessedinsuchawaythattheassessmenterror(duetonoiseandinterference)islessthan1/2symbolperiodsforstationaryMS.ForMSmovingataspeedupto500km/htheadditionalerrorshallbelessthen1/4symbolperiod.ThecontrolloopforthetimingadvanceshallbeimplementedinsuchawaythatitwillcopewithMSsmovingataspeedupto500km/h.5.6.4Pico-BTSdelaytrackingThepico-BTShasnorequirementtotracktimingadvanceforanyclassofchannels.However,itshallincludeeitherthemeasuredtimingadvanceasspecifiedaboveoraprogrammabletimingadvancevalueintheresponsefromtheBTSwhenatimingadvancevalueneedstobesent.5.7TimeslotlengthOptionally,theBTSmayuseatimeslotlengthof157symbolperiodsontimeslotswithTN=0and4,and156symbolperiodsontimeslotswithTN=1,2,3,5,6,7,ratherthan156,25symbolperiodsonalltimeslots.5.8RangeofTimingadvanceThetimingadvanceshallbeintherange0toTAmax(seeclause5.5).Thevalue0correspondstonotimingadvance,i.e.theMStransmissionstotheBTSare468,75symbolperiodsbehind(seeclause6.4).ThevalueTAmaxcorrespondstomaximumtimingadvance,i.e.theMStransmissionsare468,75-TAmaxsymbolperiodsbehind.6MSRequirementsforSynchronizationTheMSshallonlystarttotransmittotheBTSiftherequirementsofclauses6.1to6.4aremet.Theconditionsunderwhichtherequirementsofclauses6.1to6.4mustbemetshallbe3dBbelowthereferencesensitivitylevelorinputlevelforreferenceperformance,whicheverapplicable,inGSM05.05and3dBlesscarriertointerferenceratiothanthereferenceinterferenceratiosinGSM05.05.Indiscontinuousreception(DRX),theMSshouldmeettherequirementsofclauses6.1to6.3duringthetimeswhenthereceiverisrequiredtobeactive.ForCTS,theCTS-MSshallfulfilalltherequirementsofclauses6.1to6.4,6.7,6.8,6.10and6.11where«BTS»designatestheCTS-FP.TheCTS-MSshallalwaysuseaTAvalueofzero.TheCTS-MSshallonlystarttotransmittotheCTS-FPiftherequirementsofclauses6.1to6.4aremet.Theconditionsunderwhichtherequirementsofclauses6.1to6.4mustbemetshallbe3dBbelowthereferencesensitivitylevelorinputlevelforreferenceperformance,whicheverapplicable,inGSM05.05and3dBlesscarriertointerferenceratiothanthereferenceinterferenceratiosinGSM05.05.Indiscontinuous
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