3 General

27.0033GPPRelease 17Terminal Adaptation Functions (TAF) for services using synchronous bearer capabilitiesTS

3.1 Customer access configuration

The PLMN access reference configuration is described in figure 1 of 3GPP TS 24.002 [3] and 3GPP TS 27.001 [9]. The present document specifically refers to the MTs which support terminal equipments (TE1 or TE2) that use synchronous bearer capabilities.

3.2 Terminal Adaptation Function

The TAF is functionally part of an MT0, MT1 or MT2 (see 3GPP TS 24.002 [3]). The terminal adaptation provides facilities to allow manual or automatic call control functions associated with circuit switched data services, in case of ITU-T V series interfaces. The following functions are included:

‑ conversion of electrical, mechanical, functional and procedural characteristics of the ITU-T V‑series, type interfaces to those required by a PLMN;

‑ bit rate adaptation of ITU-T V‑series and ITU-T X‑series data signalling rates and the ISDN 64 kbit/s to that provided in an A/Gb mode PLMN;

‑ the mapping of ITU-T V.25 bis [18] AUTO CALL/AUTO ANSWER procedures to the PLMN Layer 3 signalling;

‑ the mapping functions necessary to convert ITU-T S‑interface signalling to PLMN Layer 3 signalling;

‑ synchronization procedure, which means the task of synchronizing the entry to and the exit from the data transfer phase between two subscriber terminals. This is described in the specification 3GPP TS 27.001 [9];

‑ filtering of channel control information. This is described in the specification 3GPP TS 27.001 [9];

‑ compatibility checking (see 3GPP TS 27.001 [9]);

‑ flow control;

‑ in Call Modification function (see clause 4);

– splitting and combining of the data flow in case of multi substream data configurations.

3.3 TAF Interfacing to other MT functions

TAF interfacing is shown in figure 1.

Figure 1: TAF interfacing to other MT functions