3 Definitions, symbols and abbreviations

06.623GPPComfort noise aspects for Enhanced Full Rate (EFR) speech traffic channelsTS

3.1 Definitions

For the purposes of the present document, the following terms and definitions apply:

frame: time interval of 20 ms corresponding to the time segmentation of the Enhanced Full Rate speech transcoder, also used as a short term traffic frame.

SID frame: frame characterized by the SID (SIlence Descriptor) codeword. It conveys information on the acoustic background noise.

SID codeword: fixed bit pattern for labelling a traffic frame as a SID frame.

SID field: bit positions of the SID codeword within a SID frame.

speech frame: traffic frame that cannot be classified as a SID frame.

VAD flag: Voice Activity Detection flag.

SP flag: SPeech flag.

Other definitions of terms used in the present document can be found in GSM 06.60 [3] and GSM 06.81 [5]. The overall operation of DTX is described in GSM 06.81 [5].

3.2 Symbols

For the purposes of the present document, the following symbols apply. Boldface symbols are used for vector variables.

Unquantized LSF vector

Quantized LSF vector

mth unquantized LSF vector of the frame

mth quantized LSF vector of the frame

Reference LSF parameter vector

Averaged LSF parameter vector

Unquantized fixed codebook gain

Quantized fixed codebook gain

Reference fixed codebook gain

Averaged fixed codebook gain

Linear prediction residual signal

Computed LSF parameter prediction residual

Quantized LSF parameter prediction residual

Computed fixed codebook gain correction factor

Quantized fixed codebook gain correction factor

3.3 Abbreviations

For the purposes of the present document, the following abbreviations apply:

BSS Base Station Subsystem

DTX Discontinuous Transmission

LP Linear Prediction

LSF Line Spectral Frequency

LSP Line Spectral Pair

MS Mobile Station

RX Receive

SID SIlence Descriptor

TX Transmit

VAD Voice Activity Detector

For abbreviations not given in this clause, see GSM 01.04 [1].