SIST EN 300 971 V8.0.1:2003

• Abstract:

  Updated to version 8.0.0 CRs from SMG#31

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.070.50 - Global System for Mobile Communication (GSM)
• Technical Committee: SS EIT - Technical Board for the electrotechnical, information technology and telecommunications fields
• 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
• Ref Project: ETSI EN 300 971 V8.0.1 (2000-11) - Digital cellular telecommunications system (Phase 2+) (GSM); Half rate speech; Comfort noise aspects for the half rate speech traffic channels (GSM 06.22 version 8.0.1 Release 1999)

SIST EN 300 971 V8.0.1:2003 is the SIST version of ETSI EN 300 971 Version 8.0.1, a GSM standard for comfort noise in half rate speech traffic channels. It specifies how the transmit side measures background noise and how the receive side recreates synthetic comfort noise when discontinuous transmission (DTX) pauses radio speech transmission. It is used by people implementing or testing GSM codec behavior in mobile stations, base stations and related speech-processing equipment.

What does SIST EN 300 971 V8.0.1:2003 specify?

SIST EN 300 971 V8.0.1:2003 specifies the comfort-noise aspects of the GSM half rate speech traffic channels. In practice, it tells implementers how to keep background noise sounding natural when speech transmission stops and restarts under DTX.

The document is organized around the GSM speech-coding context, then the comfort-noise method itself. Clause 3 defines the terms, symbols and abbreviations used in the technical description. Clause 4 explains the background-noise problem and the transmit/receive approach used to solve it.

What are the key requirements of SIST EN 300 971 V8.0.1:2003?

The core requirement in SIST EN 300 971 V8.0.1:2003 is to avoid an abrupt loss of background noise when transmission is switched off. Clause 4 states that the problem appears because the acoustic background vanishes during DTX, which can sound unnatural and make speech harder to follow in noisy environments.

The standard’s solution is to estimate comfort-noise parameters on the TX side and send them to the RX side before transmission stops, then continue sending them at a low rate afterwards. That means the receiver can keep generating noise that tracks the caller’s background instead of leaving silence.

• Clause 4 defines the purpose of the method: preserve a realistic background during DTX.
• Clause 4 describes TX-side parameter estimation. This matters because the receiver can only recreate noise if it has usable parameters.
• Clause 4 describes RX-side synthetic noise generation. This is what listeners actually hear during pauses.
• Clause 4 says the parameters are sent before radio transmission is switched off and then at a regular low rate. This lets the comfort noise follow changes in the environment.
• Clause 3.1 defines the frame types and flags used to decide whether a frame carries speech or comfort-noise information.
• Clause 3.2 defines the symbols used in the equations for energy, autocorrelation, reflection coefficients and vector-quantization data. This is important for correct implementation of the codec algorithm.
• Clause 3.3 lists the abbreviations used throughout the document, including GSM, DTX, SID, VAD, TX and RX. This helps map the procedure to the parts of the system that send and receive the frames.

What terms does SIST EN 300 971 V8.0.1:2003 define?

• SID frame - A frame characterized by the Silence Descriptor codeword; it carries information about the acoustic background noise.
• speech frame - A traffic frame that cannot be classified as a SID frame.
• SP flag - The speech flag used in the frame handling rules.
• VAD flag - The Voice Activity Detector flag used to indicate detected speech activity.
• DTX - Discontinuous Transmission, the mode where radio transmission is switched off during pauses.
• W(Z) - The spectral weighting filter of the GSM half rate speech codec.
• BSS - Base Station System, one of the system elements named in the abbreviations list.
• MS - Mobile Station, the handset or terminal side of the GSM link.

Who uses SIST EN 300 971 V8.0.1:2003?

SIST EN 300 971 V8.0.1:2003 is used by GSM equipment designers, codec developers and system integrators working on half rate speech and DTX behavior. It is also relevant for base station and mobile station engineers, because the document names both BSS and MS as the system contexts where the procedure applies.

Test labs and quality teams use it when checking how voice behaves during silence periods, especially whether comfort noise remains stable and natural. Network and product teams use it when validating that transmit-side noise estimation and receive-side reconstruction are aligned with the GSM speech-coding rules.

What changed in SIST EN 300 971 V8.0.1:2003 from the previous edition?

SIST EN 300 971 V8.0.1:2003 updates the standard to include version 8.0.0 change requests from SMG#31.

Which standards are used with SIST EN 300 971 V8.0.1:2003?

• GSM 01.04 [1] - Provides abbreviations not defined in this document.
• GSM 06.20 [2] - Provides related term definitions used in the GSM half rate speech codec context.
• GSM 06.41 [3] - Describes the overall operation of DTX and gives related terms used by this document.

These companion documents supply the wider GSM speech-coding vocabulary and the DTX framework that the comfort-noise method depends on.

What does the SIST EN 300 971 V8.0.1:2003 document contain?

SIST EN 300 971 V8.0.1:2003 contains the technical description of comfort-noise handling for GSM half rate speech traffic channels. It includes the defined terms, symbols and abbreviations, then the procedure for estimating, transmitting and reconstructing background noise under DTX.

The document also contains the mathematical notation and algorithmic detail needed to implement the method consistently on the transmitter and receiver sides. For implementers, this is the part that links the GSM speech codec variables to the behavior seen during pauses in conversation.

Its practical use is in design, codec implementation and conformance-oriented checking of speech behavior in silence periods.

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 8.0.1 Release 1999)33.070.50Globalni sistem za mobilno telekomunikacijo (GSM)Global System for Mobile Communication (GSM)ICS:Ta slovenski standard je istoveten z:EN 300 971 Version 8.0.1SIST EN 300 971 V8.0.1:2003en01-december-2003SIST EN 300 971 V8.0.1:2003SLOVENSKI
STANDARD
5SIST EN 300 971 V8.0.1:2003
ETSIETSIEN300971V8.0.1(2000-11)2(GSM06.22version8.0.1Release1999)ReferenceREN/SMG-110622Q8KeywordsDigitalcellulartelecommunicationssystem,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 300 971 V8.0.1:2003

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ETSIETSIEN300971V8.0.1(2000-11)7(GSM06.22version8.0.1Release1999)SIDframe:framecharacterizedbytheSID(SilenceDescriptor)codeword.Itconveysinformationontheacousticbackgroundnoise.SPflag:speechflag.speechframe:trafficframethatcannotbeclassifiedasaSIDframe.VADflag:VoiceActivityDetectorflag.W(Z):spectralweightingfilteroftheGSMhalfratespeechcodec.OtherdefinitionsoftermsusedinthepresentdocumentcanbefoundinGSM06.20[2]
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