06.923GPPComfort noise aspects for Adaptive Multi-Rate speech traffic channelsTS
For the purpose of the present document, the following terms and definitions apply.
Frame: time interval of 20 ms corresponding to the time segmentation of the adaptive multi-rate speech transcoder, also used as a short term for traffic frame.
SID frames: special SID (Silence Descriptor) frames. It may convey information on the acoustic background noise or inform the decoder that it should start generating background noise.
Speech frame: traffic frame that cannot be classified as a SID frame.
VAD flag: voice Activity Detection flag.
TX_TYPE: one of SPEECH, SID_FIRST, SID_UPD, NO_DATA (defined in GSM 06.93).
RX_TYPE: classification of the received traffic frame (defined in GSM 06.93).
Other definitions of terms used in the present document can be found in GSM 06.90  and GSM 06.93 . The overall operation of DTX is described in GSM 06.93 .
For the purpose of the present document, the following symbols apply. Boldface symbols are used for vector variables.
Unquantized LSF vector
Quantized LSF vector
Unquantized LSF vector of frame m
Quantized LSF vector of frame m
Averaged LSF parameter vector
Logarithmic frame energy
Averaged logarithmic frame energy
Reference vector for LSF quantization
Computed LSF parameter prediction residual
Quantized LSF parameter prediction residual
For the purpose of the present document, the following abbreviations apply.
AMR Adaptive Multi-Rate
BSS Base Station Subsystem
DTX Discontinuous Transmission
MS Mobile Station
SID SIlence Descriptor
LP Linear Prediction
LSP Line Spectral Pair
LSF Line Spectral Frequency
VAD Voice Activity Detector
For abbreviations not given in this subclause, see GSM 01.04 .