SIST EN 301 705 V7.1.1:2003
(Main)Digital cellular telecommunications system (Phase 2+) (GSM); Substitution and muting of lost frames for Adaptive Multi Rate (AMR) speech traffic channels (GSM 06.91 version 7.1.1 Release 1998)
- Abstract
Adaptive Multi- Rate (AMR) Sustitution and muting
- 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
- Mandate
- T-172
SIST EN 301 705 V7.1.1:2003 is the Slovenian adoption of ETSI EN 301 705 Version 7.1.1 for Digital cellular telecommunications system (Phase 2+) (GSM). It specifies how lost Adaptive Multi Rate (AMR) speech traffic channel frames are substituted and muted in the Receive (RX) Discontinuous Transmission (DTX) handler, so that GSM Base Station Systems (BSS) and Mobile Stations (MS) handle frame loss in a defined way.
What does SIST EN 301 705 V7.1.1:2003 specify?
SIST EN 301 705 V7.1.1:2003 defines the frame substitution and muting procedure used when one or more lost speech frames or Silence Descriptor (SID) frames are received from the Radio SubSystem (RSS). The document is aimed at AMR speech traffic channels and is mandatory for BSS and MS that support them.
The document is organized into scope, references, definitions and abbreviations, general principles, requirements, two example ECU/BFH solutions, and an informative change history annex.
What are the key requirements of SIST EN 301 705 V7.1.1:2003?
The standard focuses on concealment of lost frames and controlled muting when frame loss continues. In practice, this means the decoder must not simply stop or play corrupted speech - it must replace lost information in a way that sounds less abrupt and signals a channel problem to the user.
Frame loss detection and flags
Clause 4 and 5.1 tie error detection to the Bad Frame Indication (BFI) from the RSS, and to the Potentially Degraded Frame Indication (PDFI) derived from the soft output of the channel decoder. The TRAU also derives BSI_Abis from CRC checks on TRAU frames. For implementers, this means different parts of the GSM chain can mark frame quality and the speech decoder can react accordingly.
Lost speech frames
Clause 5.2 requires lost speech frames to be substituted by repetition or extrapolation of previous good speech frames, with the output level gradually reduced toward silence. This is the core error concealment behavior: the user hears a smoother degradation instead of unpleasant noise.
Lost SID frames
Clause 5.3 requires the first lost SID frame to be substituted using earlier valid SID information, following the valid SID procedure in GSM 06.93. Clause 5.4 requires subsequent lost SID frames to be handled by muting the comfort noise output. In practice, the decoder keeps comfort noise plausible at first, then gradually mutes it if the SID update stream stays broken.
Example state-machine handling
Clauses 6 and 7 give two example ECU/BFH solutions based on a seven-state machine. A bad frame increments the state up to 6, while a good frame resets the state, except from state 6 where it drops to 5. The state is a simple channel-quality memory, so implementers can use it to scale concealment strength as losses continue.
Active speech concealment actions
In the example solutions, when a bad speech frame is detected, the LTP gain and fixed codebook gain are replaced by attenuated values based on previous subframes and a state-dependent factor. The past LSFs are shifted toward their mean, the LTP-lag is updated from previous information, and the innovation pulses are handled according to whether corrupted data or no data were received. This matters because it preserves speech structure while reducing artifacts.
Non-active speech concealment actions
Clause 6.3 describes background-noise handling for non-active speech signals. It uses a background detector, a voicing detector, and state updates that run continuously so switching back to active speech is seamless. For lower-rate TCH-FS and TCH-HS modes, the background ECU also adjusts excitation energy, LTP lag, LTP gain, gain-contour smoothing, and anti-sparseness processing.
What terms does SIST EN 301 705 V7.1.1:2003 define?
- N-point median operation - the median is selected by sorting N values and taking the middle-ranked value as defined in the document.
- Bad Frame Indication (BFI) - a flag from the RSS showing that a received frame is bad.
- Potentially Degraded Frame Indication (PDFI) - a flag from the RSS derived from soft channel-decoder output, used when a frame may be degraded.
- Silence Descriptor (SID) - a frame type that carries comfort-noise information rather than normal speech.
- Discontinuous Transmission (DTX) - the receive-side handling mode that applies substitution and muting when frames are lost.
- Error Concealment Unit (ECU) - the unit that performs concealment actions on speech or background-noise signals.
- Bad Frame Handling (BFH) - the logic that controls how bad frames are substituted and muted.
Who uses SIST EN 301 705 V7.1.1:2003?
SIST EN 301 705 V7.1.1:2003 is used by GSM chipset, codec, base-station, and handset engineers who implement AMR receive-side error concealment. It is also relevant to quality managers and test teams verifying decoder behavior when speech frames, SID frames, or channel-encoded data are lost. In practice, it helps with implementation, integration, and conformance checking in GSM BSS and MS products.
What changed in SIST EN 301 705 V7.1.1:2003 from the previous edition?
Annex A gives the document change history. It records a version update to 7.1.1 for publication, and it also notes an earlier change concerning the use of random excitation when RX_NODATA and not in DTX.
Which standards are used with SIST EN 301 705 V7.1.1:2003?
The document relies on these referenced GSM specifications:
- GSM 05.03 - channel coding, which supports the framing and coding context.
- GSM 06.90 - AMR speech transcoding, which provides the speech decoder background.
- GSM 06.93 - DTX for AMR speech traffic channels, which defines valid SID behavior.
- GSM 08.60 - inband control of remote transcoders and rate adaptors for AMR, EFR and Full Rate traffic channels.
- GSM 08.61 - inband control of remote transcoders and rate adaptors for Half Rate traffic channels.
What does the SIST EN 301 705 V7.1.1:2003 document contain?
The document contains a state-machine based concealment procedure, formulas for limiting and attenuating LTP gain and fixed codebook gain, and rules for updating fixed codebook memory and LSF vectors. It also includes two worked example solutions in C-like form, one more detailed and one simplified. Figure 1 shows the bad-frame control state machine, and the annex provides the change history for the publication.
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Frequently Asked Questions
SIST EN 301 705 V7.1.1:2003 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Digital cellular telecommunications system (Phase 2+) (GSM); Substitution and muting of lost frames for Adaptive Multi Rate (AMR) speech traffic channels (GSM 06.91 version 7.1.1 Release 1998)". This standard covers: Adaptive Multi- Rate (AMR) Sustitution and muting
Adaptive Multi- Rate (AMR) Sustitution and muting
SIST EN 301 705 V7.1.1:2003 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 301 705 V7.1.1:2003 is associated with the following European legislation: Standardization Mandates: T-172. When a standard is cited in the Official Journal of the European Union, products manufactured in conformity with it benefit from a presumption of conformity with the essential requirements of the corresponding EU directive or regulation.
SIST EN 301 705 V7.1.1:2003 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); Substitution and muting of lost frames for Adaptive Multi Rate (AMR) speech traffic channels (GSM 06.91 version 7.1.1 Release 1998)33.070.50Globalni sistem za mobilno telekomunikacijo (GSM)Global System for Mobile Communication (GSM)ICS:Ta slovenski standard je istoveten z:EN 301 705 Version 7.1.1SIST EN 301 705 V7.1.1:2003en01-december-2003SIST EN 301 705 V7.1.1:2003SLOVENSKI
STANDARD
ETSIEN301705V7.1.1(2000-04)EuropeanStandard(Telecommunicationsseries)Digitalcellulartelecommunicationssystem(Phase2+);SubstitutionandmutingoflostframesforAdaptiveMultiRate(AMR)speechtrafficchannels(GSM06.91version7.1.1Release1998)GLOBALSYSTEMFORMOBILECOMMUNICATIONSRSIST EN 301 705 V7.1.1:2003
ETSIETSIEN301705V7.1.1(2000-04)2(GSM06.91version7.1.1Release1998)ReferenceREN/SMG-110691Q7R1KeywordsDigitalcellulartelecommunicationssystem,GlobalSystemforMobilecommunications(GSM),AMRETSI650RoutedesLuciolesF-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 301 705 V7.1.1:2003
ETSIETSIEN301705V7.1.1(2000-04)3(GSM06.91version7.1.1Release1998)ContentsIntellectualPropertyRights.4Foreword.41Scope.52References.53Definitionsandabbreviations.53.1Definitions.53.2Abbreviations.64General.65Requirements.65.1Errordetection.65.2Lostspeechframes.65.3FirstlostSIDframe.65.4SubsequentlostSIDframes.76ExampleECU/BFHSolution1.76.1StateMachine.76.2AssumedActiveSpeechFrameErrorConcealmentUnitActions.86.2.1BFI=0,prevBFI=0,State=0.86.2.2BFI=0,prevBFI=1,State=0or5.86.2.3BFI=1,prevBFI=0or1,State=1.6.96.2.3.1LTP-lagupdate.96.2.3.2Innovationsequence.96.3AssumedNon-ActiveSpeechSignalErrorConcealmentUnitActions.106.3.1General.106.3.2Detectors.106.3.2.1Backgrounddetector.106.3.2.2Voicingdetector.106.3.3BackgroundECUActions.106.4SubstitutionandmutingoflostSIDframes.107ExampleECU/BFHSolution2.117.1StateMachine.117.2Substitutionandmutingoflostspeechframes.117.2.1BFI=0,prevBFI=0,State=0.117.2.2BFI=0,prevBFI=1,State=0or5.117.2.3BFI=1,prevBFI=0or1,State=1.6.127.2.3.1LTP-lagupdate.127.2.4Innovationsequence.127.3SubstitutionandmutingoflostSIDframes.12AnnexA(informative):Documentchangehistory.13History.14SIST EN 301 705 V7.1.1:2003
ETSIETSIEN301705V7.1.1(2000-04)4(GSM06.91version7.1.1Release1998)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).ThepresentdocumentintroducestheAdaptiveMulti-Rate(AMR)speechtrafficchannelswithinthedigitalcellulartelecommunicationssystem.ThecontentsofthepresentdocumentissubjecttocontinuingworkwithinSMGandmaychangefollowingformalSMGapproval.ShouldSMGmodifythecontentsofthepresentdocumentitwillbere-releasedwithanidentifyingchangeofreleasedateandanincreaseinversionnumberasfollows:Version7.x.ywhere:7indicatesRelease1998ofGSMPhase2+.xtheseconddigitisincrementedforallchangesofsubstance,i.e.technicalenhancements,corrections,updates,etc.ythethirddigitisincrementedwheneditorialonlychangeshavebeenincorporatedinthespecification.NationaltranspositiondatesDateofadoptionofthisEN:31March2000DateoflatestannouncementofthisEN(doa):30June2000DateoflatestpublicationofnewNationalStandardorendorsementofthisEN(dop/e):31December2000DateofwithdrawalofanyconflictingNationalStandard(dow):31December2000SIST EN 301 705 V7.1.1:2003
ETSIETSIEN301705V7.1.1(2000-04)5(GSM06.91version7.1.1Release1998)1ScopeThepresentdocumentdefinesaframesubstitutionandmutingprocedurewhichshallbeusedbytheReceive(RX)DiscontinuousTransmission(DTX)handlerwhenoneormorelostspeechorSilenceDescriptor(SID)framesarereceivedfromtheRadioSubSystem(RSS).TherequirementsofthepresentdocumentaremandatoryforimplementationinallGSMBaseStationSystems(BSS)sandMobileStations(MS)scapableofsupportingtheAMRspeechtrafficchannel.ItisnotmandatorytofollowthebitexactimplementationoutlinedinthepresentdocumentandthecorrespondingCsourcecode.2ReferencesThefollowingdocumentscontainprovisionswhich,throughreferenceinthistext,constituteprovisionsofthepresentdocument.• Referencesareeitherspecific(identifiedbydateofpublication,editionnumber,versionnumber,etc.)ornon-specific.• Foraspecificreference,subsequentrevisionsdonotapply.• Foranon-specificreference,thelatestversionapplies.• Anon-specificreferencetoanETSshallalsobetakentorefertolaterversionspublishedasanENwiththesamenumber.• ForthisRelease1998document,referencestoGSMdocumentsareforRelease1998versions(version7.x.y).[1]GSM05.03:"Digitalcellulartelecommunicationssystem(Phase2+);Channelcoding".[2]GSM06.90:"Digitalcellulartelecommunicationssystem(Phase2+);AMRspeechtranscoding".[3]GSM06.93:"Digitalcellulartelecommunicationssystem(Phase2+);Discontinuoustransmission(DTX)forAdaptiveMultiRate(AMR)speechtrafficchannels".[4]GSM08.60:"Digitalcellulartelecommunicationssystem(Phase2+);InbandcontrolofremotetranscodersandrateadaptorsforAMR,EnhancedFullRate(EFR)andFullRatetrafficchannels".[5]GSM08.61:"Digitalcellulartelecommunicationssystem(Phase2+);InbandcontrolofremotetranscodersandrateadaptorsforHalfRatetrafficchannels".3Definitionsandabbreviations3.1DefinitionsForthepurposesofthepresentdocument,thefollowingtermsanddefinitionsapply.N-pointmedianoperation:ConsistsofsortingtheNelementsbelongingtothesetforwhichthemedianoperationistobeperformedinanascendingorderaccordingtotheirvalues,andselectingthe(int(N/2)+1)-thelargestvalueofthesortedsetasthemedianvalue.FurtherdefinitionsoftermsusedinthepresentdocumentcanbefoundinGSM06.90[2],GSM06.93[3],GSM05.03[1]andGSM08.60[4].SIST EN 301 705 V7.1.1:2003
ETSIETSIEN301705V7.1.1(2000-04)6(GSM06.91version7.1.1Release1998)3.2AbbreviationsForthepurposesofthepresentdocument,thefollowingabbreviationsapply:BFIBadFrameIndicationfromRadioSubSystemBSI_AbisBadSub-blockIndicationobtainedfromA-bisCRCchecksprevBFIBadFrameIndicationofpreviousframePDFIPotentiallyDegradedFrameIndicationfromRSSRSSRadioSubSystemRXReceiveDTXDiscontinuousTransmissionSIDSIlenceDescriptorframe(Backgrounddescriptor)CRCCyclicRedundancyCheckCCUChannelCodingUnitECUErrorConcealmentUnitBFHBadFrameHandlingmedianNN-pointmedianoperationTRAUTranscodingRateAdaptationUnit4GeneralThepurposeofframesubstitutionistoconcealtheeffectoflostframes.Thepurposeofmutingtheoutputinthecaseofseverallostframesistoindicatethebreakdownofthechanneltotheuserandtoavoidgeneratingpossibleannoyingsoundsasaresultfr
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