When 64 kbit/s traffic channels are used on the A-bis interface, the speech shall be coded according to CCITT Recommendation G.711 and the data rate adaptation shall be as specified in TS 44.021
and TS 48.020
In the case where 16 kbit/s traffic channels are used for full rate speech, enhanced full rate speech, Adaptive Multi-Rate speech, Adaptive Multi-Rate Wideband speech or full rate data service, then this TS shall apply for frame structure and for control of remote transcoders and additional rate adaptors.
For Adaptive Multi-Rate speech this TS specifies the 16 kBit/s submultiplexing, both for the full and the half rate traffic channels (TCH/AFS, TCH/AHS, TCH/WFS and O-TCH/WHS). The specification for 8 kBit/s submultiplexing is given in TS 48.061
, both for the full and the half rate traffic channels (TCH/AFS and TCH/AHS).
Additionally, this TS specifies the 32 kBit/s submultiplexing for Adaptive Multi-Rate Wideband speech. However it reuses the frame structure of the 16 kBit/s submultiplexing for Adaptive Multi-Rate speech.
The use and general aspects of the A-bis interface are given in TS 48.051
This TS should be considered together with the GSM TS 06 series of specifications, TS 44.021 (Rate Adaptation on the MS-BSS Interface) and TS 48.020 (Rate Adaptation on the BS/MSC Interface).