06.623GPPComfort noise aspects for Enhanced Full Rate (EFR) speech traffic channelsTS
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  and GSM 06.81 . The overall operation of DTX is described in GSM 06.81 .
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
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
SID SIlence Descriptor
VAD Voice Activity Detector
For abbreviations not given in this clause, see GSM 01.04 .