06.933GPPDiscontinuous Transmission (DTX) for Adaptive Multi-Rate speech traffic channelsTS

3.1 Definitions

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 (GSM 06.90 [9]), also used as a short term for a traffic frame

traffic frame: block of 95.244 information bits transmitted on the TCH/AFS or TCH/AHS speech traffic channels

SID frame: frame characterised by the SID (Silence Descriptor) gross bit patterns. It may convey information on the acoustic background noise

speech frame: traffic frame that has been classified as a SPEECH frame

VAD flag: boolean flag, generated by the VAD algorithm defined in GSM 06.94 indicating the presence ("1") or the absence ("0") of a speech frame

RX_TYPE: flag with eight values, generated by the RX radio subsystem, indicating to the RX DTX handler the type of data in the current frame (efer to table 2)

TX_TYPE: flag with eight values, generated by the TX DTX handler, indicating to the TX radio subsystem the type of data in the current frame (refer to table 1)

hangover period: period of 7 frames added at the end of a speech burst in which VAD flag ="0" and TX_TYPE is "SPEECH"

3.2 Symbols

For the purpose of the present document, the following symbol apply:

Nelapsed Number of elapsed frames since the last updated SID frame

3.3 Abbreviations

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

BSC Base Station Controller

BSS Base Station System

BTS Base Transceiver Station

CHD Channel Decoder

CHE Channel Encoder

DTX Discontinuous Transmission

ETS European Telecommunication Standard

FACCH Fast Associated Control CHannel

GSM Global System for Mobile Telecommunications

MS Mobile Station

RATSCCH Robust Amr Traffic Synchronised Control CHannel

RSS Radio Sub System

RX Receive

SACCH Slow Associated Control CHannel

SID SIlence Descriptor

TX Transmit

VAD Voice Activity Detector

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