SIST EN 300 971 V7.0.1:2003
(Main)Digital cellular telecommunications system (Phase 2+) (GSM); Half rate speech; Comfort noise aspects for the half rate speech traffic channels (GSM 06.22 version 7.0.1 Release 1998)
- Abstract
Upgrade from Phase 2+ to Release 1998
- 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 300 971 V7.0.1:2003 is the Slovene adoption of ETSI EN 300 971 version 7.0.1 for GSM half rate speech comfort noise aspects. It specifies how background acoustic noise is evaluated, encoded, signalled, and regenerated for half rate speech traffic channels in GSM Mobile Stations (MS) and Base Station Systems (BSS) during Discontinuous Transmission (DTX). The document is aimed at implementers of GSM MS and BSS who need the comfort noise behaviour to match the GSM half rate speech specification.
What does SIST EN 300 971 V7.0.1:2003 specify?
SIST EN 300 971 V7.0.1:2003 specifies the detailed operation of comfort noise for GSM half rate speech traffic channels. Clause 1 ties the requirements to MS and BSS operation during DTX, and the document focuses on the transmit side, receive side, and the computational details used to implement them.
The document is organised into:
- Clause 1 Scope
- Clause 2 References
- Clause 3 Definitions, symbols and abbreviations
- Clause 4 General
- Clause 5 Functions on the transmit (TX) side
- Clause 6 Functions on the receive (RX) side
- Clause 7 Computational details
- Annex A, informative, Change Request History
Annex A records the change request history for the Release 1998 version.
What are the key requirements of SIST EN 300 971 V7.0.1:2003?
The core requirement is that comfort noise shall be generated from recent speech parameters so that background noise does not disappear abruptly when radio transmission is switched off. In practice, this is what keeps pauses in conversation from sounding unnatural or “dead”.
Transmit-side behaviour
Clause 5.1 defines how the transmitter derives the comfort noise parameters from recent frames. The frame energy value R0 and the autocorrelation sequence R(i) are averaged over 8 consecutive frames marked with VADflag "0", while GS is averaged over the last 7 speech frames. This means the encoder must keep short-term history and use it to represent the background noise, not just the current frame.
Clause 5.2 changes the speech encoding process when SPflag is "0". The encoder does not quantize the reflection coefficients used for H(Z) and W(Z), forces unvoiced mode, avoids fixed codebook search, and replaces fixed codebook indices with pseudorandom numbers. In practice, this simplifies encoding during comfort noise insertion and makes the generated signal behave like noise rather than speech.
Clause 5.3 defines SID-frame encoding. The SID frame uses the voiced-frame output format, replaces the energy and reflection-coefficient information with averaged comfort noise parameters, and marks the frame with a fixed SID codeword. This lets the receiver recognize the frame as comfort-noise signalling and not as ordinary speech.
Receive-side behaviour
Clause 6.1 requires the decoder to store GS values from the last seven speech frames and average them when the first valid SID frame arrives. The averaged GS is then frozen for the whole comfort-noise insertion period. In practice, the decoder must preserve recent speech state so it can rebuild the same noise character as the transmitter.
Clause 6.2 sets the comfort-noise generation parameters. R0 and the LPC-related values are interpolated from the last two valid SID frames, the codebook indices for the excitation are pseudorandom, and the GSP0 codeword is frozen during the insertion period. This gives smooth transitions when noise is started or updated.
Clause 7 points to a low-level ANSI-C description in GSM06.06. That matters for implementers who need code-level guidance rather than only the normative text.
What terms does SIST EN 300 971 V7.0.1:2003 define?
- Discontinuous Transmission (DTX) - a mode where radio transmission is switched off during pauses to reduce unnecessary transmission.
- SID frame - a frame marked by the Silence Descriptor codeword that carries comfort-noise information.
- SID codeword - the fixed bit pattern used to identify a SID frame.
- VADflag - the Voice Activity Detector flag that shows whether a frame is treated as voice activity or not.
- SPflag - the speech flag that controls whether the encoder continues speech processing during hangover and SID handling.
- MS - Mobile Station, the GSM terminal side covered by the transmit requirements.
- BSS - Base Station System, the network-side equipment covered by the receive requirements.
Who uses SIST EN 300 971 V7.0.1:2003?
SIST EN 300 971 V7.0.1:2003 is used by GSM codec and radio implementers working on half rate speech traffic channels. That includes handset and terminal developers, base station and network equipment vendors, and software teams implementing DTX, VAD, SID handling, and comfort-noise synthesis.
It is also relevant to test laboratories, integration teams, and quality managers who need to verify that MS and BSS implementations produce and decode comfort noise in the same way. In practice, it supports interoperability between speech encoders, decoders, and radio subsystems.
What changed in SIST EN 300 971 V7.0.1:2003 from the previous edition?
SIST EN 300 971 V7.0.1:2003 is the Release 1998 version, and Annex A records the change request history leading to version 7.0.1. The history shows the document progression through earlier release versions and the publication update to 7.0.1.
Which standards are used with SIST EN 300 971 V7.0.1:2003?
- GSM01.04 - provides the abbreviations and acronyms used when a term is not defined here.
- GSM06.20 - defines half rate speech transcoding and the decoder/encoder behaviour that this document builds on.
- GSM06.41 - defines Discontinuous Transmission (DTX) behaviour for half rate speech traffic channels.
- GSM06.42 - defines the Voice Activity Detector (VAD) for half rate speech traffic channels.
- GSM06.06 - provides the ANSI-C code for the GSM half rate speech codec, including the computational detail referenced in Clause 7.
What does the SIST EN 300 971 V7.0.1:2003 document contain?
The document contains the averaging equations used to derive comfort-noise parameters from recent frames, including the handling of R0, R(i), and GS. It also contains a SID codeword table that shows how a frame is marked as a SID frame.
It includes a table of comfort-noise encoded parameters for the receive side, showing how decoder fields are set during insertion and update. A simplified block diagram illustrates the encoder behaviour in comfort-noise insertion mode.
The document also gives the practical encoding and decoding steps for SID frames and comfort noise updates, and it points to an ANSI-C source-code description for computational implementation.
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Frequently Asked Questions
SIST EN 300 971 V7.0.1:2003 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Digital cellular telecommunications system (Phase 2+) (GSM); Half rate speech; Comfort noise aspects for the half rate speech traffic channels (GSM 06.22 version 7.0.1 Release 1998)". This standard covers: Upgrade from Phase 2+ to Release 1998
Upgrade from Phase 2+ to Release 1998
SIST EN 300 971 V7.0.1:2003 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 300 971 V7.0.1:2003 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 300 971 V7.0.1:2003 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); Half rate speech; Comfort noise aspects for the half rate speech traffic channels (GSM 06.22 version 7.0.1 Release 1998)33.070.50Globalni sistem za mobilno telekomunikacijo (GSM)Global System for Mobile Communication (GSM)ICS:Ta slovenski standard je istoveten z:EN 300 971 Version 7.0.1SIST EN 300 971 V7.0.1:2003en01-december-2003SIST EN 300 971 V7.0.1:2003SLOVENSKI
STANDARD
ETSIEN300971V7.0.1(2000-01)EuropeanStandard(Telecommunicationsseries)Digitalcellulartelecommunicationssystem(Phase2+);Halfratespeech;Comfortnoiseaspectsforthehalfratespeechtrafficchannels(GSM06.22version7.0.1Release1998)GLOBALSYSTEMFORMOBILECOMMUNICATIONSRSIST EN 300 971 V7.0.1:2003
ETSIETSIEN300971V7.0.1(2000-01)2(GSM06.22version7.0.1Release1998)ReferenceREN/SMG-110622Q7KeywordsDigitalcellulartelecommunicationssystem,GlobalSystemforMobilecommunications(GSM)ETSIPostaladdressF-06921SophiaAntipolisCedex-FRANCEOfficeaddress650RoutedesLucioles-SophiaAntipolisValbonne-FRANCETel.:+33492944200Fax:+33493654716SiretN°34862356200017-NAF742CAssociationàbutnonlucratifenregistréeàlaSous-PréfecturedeGrasse(06)N°7803/88Internetsecretariat@etsi.frIndividualcopiesofthisETSIdeliverablecanbedownloadedfromhttp://www.etsi.orgIfyoufinderrorsinthepresentdocument,sendyourcommentto:editor@etsi.frImportantnoticeThisETSIdeliverablemaybemadeavailableinmorethanoneelectronicversionorinprint.Inanycaseofexistingorperceiveddifferenceincontentsbetweensuchversions,thereferenceversionisthePortableDocumentFormat(PDF).Incaseofdispute,thereferenceshallbetheprintingonETSIprintersofthePDFversionkeptonaspecificnetworkdrivewithinETSISecretariat.CopyrightNotificationNopartmaybereproducedexceptasauthorizedbywrittenpermission.Thecopyrightandtheforegoingrestrictionextendtoreproductioninallmedia.©EuropeanTelecommunicationsStandardsInstitute2000.Allrightsreserved.SIST EN 300 971 V7.0.1:2003
ETSIETSIEN300971V7.0.1(2000-01)3(GSM06.22version7.0.1Release1998)ContentsIntellectualPropertyRights.4Foreword.41Scope.62References.63Definitions,symbolsandabbreviations.63.1Definitions.63.2Symbols.73.3Abbreviations.74General.75Functionsonthetransmit(TX)side.85.1Backgroundacousticnoiseevaluation.85.2ModificationofthespeechencodingalgorithmduringSIDframegeneration.95.3SID-frameencoding.106Functionsonthereceive(RX)side.116.1AveragingoftheGSparameters.116.2Comfortnoisegenerationandupdating.127Computationaldetails.12AnnexA(informative):ChangeRequestHistory.13History.14SIST EN 300 971 V7.0.1:2003
ETSIETSIEN300971V7.0.1(2000-01)4(GSM06.22version7.0.1Release1998)IntellectualPropertyRightsIPRsessentialorpotentiallyessentialtothepresentdocumentmayhavebeendeclaredtoETSI.TheinformationpertainingtotheseessentialIPRs,ifany,ispubliclyavailableforETSImembersandnon-members,andcanbefoundinSR000314:"IntellectualPropertyRights(IPRs);Essential,orpotentiallyEssential,IPRsnotifiedtoETSIinrespectofETSIstandards",whichisavailablefromtheETSISecretariat.LatestupdatesareavailableontheETSIWebserver(http://www.etsi.org/ipr).PursuanttotheETSIIPRPolicy,noinvestigation,includingIPRsearches,hasbeencarriedoutbyETSI.NoguaranteecanbegivenastotheexistenceofotherIPRsnotreferencedinSR000314(ortheupdatesontheETSIWebserver)whichare,ormaybe,ormaybecome,essentialtothepresentdocument.ForewordThisEuropeanStandard(Telecommunicationsseries)hasbeenproducedbytheSpecialMobileGroup(SMG).Thepresentdocumentgivesthedetailedrequirementsforthecorrectoperationofthebackgroundacousticnoiseevaluation,noiseparameterencoding/decodingandcomfortnoisegenerationwithinthedigitalcellulartelecommunicationssystem.Thepresentdocumentispartofaseriescoveringthehalfratespeechtrafficchannelsasdescribedbelow:GSM06.02"Digitalcellulartelecommunicationssystem(Phase2+);Halfratespeech;Halfratespeechprocessingfunctions".GSM06.06"Digitalcellulartelecommunicationssystem(Phase2+);Halfratespeech;ANSI-CcodefortheGSMhalfratespeechcodec".GSM06.07"Digitalcellulartelecommunicationssystem(Phase2+);Halfratespeech;TestsequencesfortheGSMhalfratespeechcodec".GSM06.20"Digitalcellulartelecommunicationssystem(Phase2+);Halfratespeech;Halfratespeechtranscoding".GSM06.21"Digitalcellulartelecommunicationssystem(Phase2+);Halfratespeech;Substitutionandmutingoflostframesforhalfratespeechtrafficchannels".GSM06.22"Digitalcellulartelecommunicationssystem(Phase2+);Halfratespeech;Comfortnoiseaspectsforhalfratespeechtrafficchannels".GSM06.41"Digitalcellulartelecommunicationssystem(Phase2+);Halfratespeech;DiscontinuousTransmission(DTX)forhalfratespeechtrafficchannels".GSM06.42"Digitalcellulartelecommunicationssystem(Phase2+);Halfratespeech;VoiceActivityDetector(VAD)forhalfratespeechtrafficchannels".ThecontentsofthepresentdocumentissubjecttocontinuingworkwithinSMGandmaychangefollowingformalSMGapproval.ShouldSMGmodifythecontentsofthepresentdocumentitwillbere-releasedwithanidentifyingchangeofreleasedateandanincreaseinversionnumberasfollows:Version7.x.ywhere:7indicatesRelease1998ofGSMPhase2+.xtheseconddigitisincrementedforallchangesofsubstance,i.e.technicalenhancements,corrections,updates,etc.ythethirddigitisincrementedwheneditorialonlychangeshavebeenincorporatedinthespecification.SIST EN 300 971 V7.0.1:2003
ETSIETSIEN300971V7.0.1(2000-01)5(GSM06.22version7.0.1Release1998)NationaltranspositiondatesDateofadoptionofthisEN:31December1999DateoflatestannouncementofthisEN(doa):31March2000DateoflatestpublicationofnewNationalStandardorendorsementofthisEN(dop/e):30September2000DateofwithdrawalofanyconflictingNationalStandard(dow):30September2000SIST EN 300 971 V7.0.1:2003
ETSIETSIEN300971V7.0.1(2000-01)6(GSM06.22version7.0.1Release1998)1ScopeThepresentdocumentgivesthedetailedrequirementsforthecorrectoperationofthebackgroundacousticnoiseevaluation,noiseparameterencoding/decodingandcomfortnoisegenerationinGSMMobileStations(MS)sandBaseStationSystems(BSS)sduringDiscontinuousTransmission(DTX)onhalfratespeechtrafficchannels.TherequirementsdescribedinthepresentdocumentaremandatoryforimplementationinallGSMMSscapableofsupportingthehalfratespeechtrafficchannel.ThereceiverrequirementsaremandatoryforimplementationinallGSMBSSscapableofsupportingthehalfratespeechtrafficchannel,thetransmitterrequirementsareonlyforthosewheredownlinkDTXwillbeused.2ReferencesThefollowingdocumentscontainprovisionswhich,throughreferenceinthistext,constituteprovisionsofthepresentdocument.•Referencesareeitherspecific(identifiedbydateofpublication,editionnumber,versionnumber,etc.)ornon-specific.•Foraspecificreference,subsequentrevisionsdonotapply.•Foranon-specificreference,thelatestversionapplies.•Anon-specificreferencetoanETSshallalsobetakentorefertolaterversionspublishedasanENwiththesamenumber.•ForthisRelease1998document,referencestoGSMdocumentsareforRelease1998versions(version7.x.y).[1]GSM01.04:"Digitalcellulartelecommunicationsystem(Phase2+);Abbreviationsandacronyms".[2]GSM06.20:"Digitalcellulartelecommunicationssystem(Phase2+);Halfratespeechtranscoding".[3]GSM06.41:"Digitalcellulartelecommunicationssystem(Phase2+);Halfratespeech;DiscontinuousTransmission(DTX)forhalfratespeechtrafficchannels".[4]GSM06.42:"Digitalcellulartelecommunicationssystem(Phase2+);"Halfratespeech;VoiceActivityDetector(VAD)forhalfratespeechtrafficchannels".[5]GSM06.06:"Digitalcellulartelecommunicationssystem(Phase2+);Halfratespeech;ANSI-CcodefortheGSMhalfratespeechcodec".3Definitions,symbolsandabbreviations3.1DefinitionsForthepurposesofthepresentdocument,thefollowingtermsanddefinitionsapply.frame:Timeintervalof20mscorrespondingtothetimesegmentationofthehalfratespeechtranscoder,alsousedasashorttermforatrafficframe.H(Z):Combinationoftheshortterm(spectral)filterA(z)andthespectralweightingfilterW(z).SIDcodeword:FixedbitpatternforlabellingatrafficframeasaSIDframe.SIDfield:ThebitpositionsoftheSIDcodewordwithinaSIDframe.SIST EN 300 971 V7.0.1:2003
ETSIETSIEN300971V7.0.1(2000-01)7(GSM06.22version7.0.1Release1998)SIDframe:FramecharacterizedbytheSID(SilenceDescriptor)codeword.Itconveysinformationontheacousticbackgroundnoise.SPflag:SPeechflag.speechframe:TrafficframethatcannotbeclassifiedasaSIDframe.VADflag:VoiceActivityDetectorflag.W(Z):SpectralweightingfilteroftheGSMhalfratespeechcodec.OtherdefinitionsoftermsusedinthepresentdocumentcanbefoundinGSM06.20[2]andGSM06.41[3].TheoveralloperationofDTXisdescribedinGSM06.41[3].3.2SymbolsForthepurposesofthepresentdocument,thefollowingsymbolsapply:GSEnergytweakparameter.R0Frameenergyvalue.R(i)Unquantised(normalized)autocorrelationsequence.rjOptimalreflectioncoefficient.bSUM(x(n))=x(a)+x(a+1)+.+x(b-1)+x(b);(Accumulation).n=aGSP0codewordVectorquantizationindex,jointvectorquantizationoftheparametersGSandP0.P0Powercontributionofthefirstexcitationvectorasafractionofthetotalexcitationpoweratasubframe.3.3AbbreviationsForthepurposesofthepresentdocument,thefollowingabbreviationsapply:AFLATAutocorrelationFixedPointLAtticeTechnique(usedintheGSMhalfratespeechcodecforthevectorquantizationofthe
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