SIST EN 300 962 V8.0.1:2003

SIST EN 300 962 V8.0.1:2003 is the Slovenian adoption of ETSI EN 300 962 Version 8.0.1 for Digital cellular telecommunications system (Phase 2+) (GSM). It specifies how GSM equipment handles lost full rate speech and SID frames by substitution and muting, so implementations in GSM Base Station Systems (BSS) and Mobile Stations (MS) treat frame loss in a defined way.

What does SIST EN 300 962 V8.0.1:2003 specify?

SIST EN 300 962 V8.0.1:2003 specifies the frame substitution and muting procedure used by the RX DTX handler when one or more lost speech or SID frames are received from the radio subsystem. The requirements are mandatory for implementation in all GSM Base Station Systems (BSS) and Mobile Stations (MS).

The document is organized into:

• Scope
• References
• Definitions and abbreviations
• General
• Requirements
• Example solution
• Annex A with change request history

What are the key requirements of SIST EN 300 962 V8.0.1:2003?

SIST EN 300 962 V8.0.1:2003 sets out a simple rule set for lost-frame handling: conceal the first loss, mute on repeated loss, and treat speech frames and SID frames differently. In practice, this lets implementers keep speech sounding natural for as long as possible, then fade to silence to show that the channel has broken down.

Lost speech frames

Clause 5.1 requires the first lost speech frame to be replaced by a repetition or extrapolation of previous good speech frame(s). The lost frame must not be passed to the speech decoder, and the output must not be muted immediately. This means the receiver should hide a single error rather than creating an obvious audio glitch.

Clause 5.2 requires subsequent lost speech frames to use muting that gradually reduces the output level until silence, with a maximum time of 320 ms. Clause 6 gives an example method. This gives a controlled fade-out instead of repeated noise bursts.

Lost SID frames

Clause 5.3 requires a single lost SID frame to be replaced by the last valid SID frame, and the procedure for valid SID frames from GSM 06.31 to be applied. In practice, this preserves comfort noise behavior when only one SID frame is missing.

Clause 5.4 requires the second lost SID frame to trigger gradual muting of the comfort noise, again reaching silence within a maximum of 320 ms. For further lost SID frames, the output remains muted. This tells the user that the channel is no longer delivering usable speech or comfort noise.

Example solution

Clause 6 gives an example muting solution using the GSM 06.10 parameter Xmaxcr. The example decreases Xmaxcr by a constant value of 4 per frame, chooses grid position parameters randomly between 0 and 3, and then sends silence frames once the lowest level is reached. Table 1 defines the encoded parameters of the silence frame. This is useful when implementing the receiver logic and when testing whether a decoder follows the intended fade-out behavior.

What terms does SIST EN 300 962 V8.0.1:2003 define?

SIST EN 300 962 V8.0.1:2003 uses the terms and abbreviations defined through GSM 01.04 and GSM 06.31, together with the speech terms used in the requirements. The most important ones for readers are:

• GSM - Global System for Mobile communications, the cellular system to which the document applies.
• BSS - Base Station Systems, one of the implementation targets named in the scope.
• MS - Mobile Stations, the other implementation target named in the scope.
• RX DTX handler - the receiver-side DTX handler that applies substitution and muting when frames are lost.
• SID frame - a frame used with comfort noise handling in DTX operation.
• Full rate speech channel - a GSM speech channel that uses full rate speech handling.
• Xmaxcr - the pseudo-logarithmic encoded block amplitude used in the example muting procedure.

Who uses SIST EN 300 962 V8.0.1:2003?

SIST EN 300 962 V8.0.1:2003 is used by GSM equipment designers, codec developers, and radio subsystem engineers who implement lost-frame handling in BSS and MS products. It is also relevant to test laboratories and conformance teams that need to verify that speech and comfort noise behave correctly when frames are missing.

Quality managers and buyers can use it to check whether a GSM device claims support for the standard frame substitution and muting behavior for full rate speech channels. That matters when comparing implementations that must sound consistent under radio errors.

What changed in SIST EN 300 962 V8.0.1:2003 from the previous edition?

SIST EN 300 962 V8.0.1:2003 is the publication version of the GSM Phase 2+ full rate speech lost-frame handling specification. The scope notes an update to Version 8.0.0 change requests from SMG#31, and Annex A records the move to Version 8.0.1 for publication.

Which standards are used with SIST EN 300 962 V8.0.1:2003?

SIST EN 300 962 V8.0.1:2003 cites these normative references:

• GSM 01.04 - provides the abbreviations and acronyms used in the document.
• GSM 06.10 - provides full rate speech transcoding details, including parameters used in the example solution.
• GSM 06.31 - provides full rate speech DTX behavior and the handling of valid SID frames.

For this Release 1999 document, referenced GSM documents are taken as the Release 1999 versions.

What does the SIST EN 300 962 V8.0.1:2003 document contain?

The document contains a short specification focused on one receiver behavior: what to do when speech or SID frames are lost. Clause 5 separates the behavior for the first loss and for repeated loss, while Clause 6 gives an example implementation based on Xmaxcr reduction and silence frames.

It also includes a small parameter table for the silence frame in GSM 06.10 format. Annex A provides the change request history, which helps trace how the specification reached Version 8.0.1.