3 Definitions and abbreviations

3GPP46.031Discontinuous Transmission (DTX) for full rate speech traffic channelsFull rate speechRelease 17TS

Abbreviations used in the present document are listed in GSM 01.04.

3.1 Definition of general terms

frame: time interval of 20 msec. corresponding to the time segmentation of the full rate speech transcoder (GSM 06.10), also used as a short term for a traffic frame.

traffic frame: block of 260 information bits (see GSM 05.03) transmitted on the full rate speech traffic channel.

(SID) silence descriptor frame: frame characterized by the SID code word. It conveys information on the acoustic background noise.

SID code word: fixed bit pattern defined in GSM 06.12, for labelling a traffic frame as a SID frame.

SID field: bit positions defined in GSM 06.12, of the SID codeword within a SID frame.

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

3.2 Definition of terms on the receive side

bad traffic frame: traffic frame flagged BFI=1 (Bad Frame Indication) by the Radio Subsystem.

good traffic frame: traffic frame flagged BFI=0 by the Radio Subsystem.

good speech frame: good traffic frame which is not an accepted SID frame.

accepted SID frame: traffic frame in which the SID field deviates in less than 16 bit positions from the SID code word (flag SID=2 or SID=1).

valid SID frame: good traffic frame in which the SID field deviates in less than 2 bit positions from the SID code word (flag SID=2). This frame is valid for updating of comfort noise parameters at any time.

invalid SID frame: accepted SID frame with BFI=1, or accepted SID frame with BFI=0, in which the SID field deviates in more than 1 bit position from the SID code word (flag SID=1). This frame is not valid for updating comfort noise parameters, but the frame conveys information that comfort noise generations should be started or continued.

unusable frame: bad traffic frame that is not an accepted SID frame.

lost SID frame: unusable frame received when the RX DTX Handler is generating comfort noise and a SID frame is expected (Time Alignment Flag, TAF=1).

lost speech frame: unusable frame received when the RX DTX Handler is passing on traffic frames directly to the speech decoder.