The present document gives the detailed requirements for the correct operation of the background acoustic noise evaluation, noise parameter encoding/decoding and comfort noise generation for the AMR speech codec during Source Controlled Rate (SCR) operation.
The requirements described in the present document are mandatory for implementation in all UEs capable of supporting the AMR speech codec.
The receiver requirements are mandatory for implementation in all networks capable of supporting the AMR speech codec, the transmitter requirements only for those where downlink SCR will be used.
In case of discrepancy between the requirements described in the present document and the fixed point computational description of these requirements contained in , the description in  will prevail.
The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
References are either specific (identified by date of publication, edition number, version number, etc.) or non specific.
For a specific reference, subsequent revisions do not apply.
For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
 TS 26.073
"Adaptive Multi-Rate (AMR); ANSI C source code".
 TS 26.090
: "Transcoding functions".
 TS 26.091
"Mandatory Speech Codec speech processing functions; AMR Speech Codec; Error concealment of lost frames".
 TS 26.093
"Source Controlled Rate operation ".
 TS 26.101