4 General

23.2023GPPCircuit switched data bearer servicesRelease 17TS

CS data services in UMTS are divided according to 3GPP TS 22.001 [1] into Bearer Services (3GPP TS 22.002 [4]) and end-to-end Teleservices (3GPP TS 22.003 [3]). These services are built on services provided by the Access Network. The Radio Access Bearer Services are invoked through the RNL-SAP provided by the Iu User Plane to the Non-access stratum on the Core Network side, and the corresponding SAP provided by the RLC to the Non-access stratum on the Terminal side. Figure 1 shows the service architecture.

Figure 1: Service architecture

4.1 Limited set of UTRAN Iu mode PLMN connection models

4.1.1 Transparent data

Figure 2 shows the connection model for synchronous transparent CS data. In general all the user data bits are conveyed between the MT and the IWF as they are received from the TE. This implies that the RLC SDU/ Iu UP frame is transparent.

Figure 3 shows the connection model for asynchronous transparent CS data. The rate adaptation function RA0 from 3GPP TS 44.021 [18] (adapted to the RLC SDU size) is used for converting between asynchronous data and a synchronous bit stream. End-to-end flow control is not applicable in UTRAN Iu mode, thus no status bits are conveyed over RAN/UTRAN (see 3GPP TS 27.001 [14]).

Figure 2: Connection model for Synchronous T CS data

Figure 3: Connection model for Asynchronous T CS data

4.1.2 Non-transparent data

Figure 4 shows the connection model for asynchronous non-transparent CS data.

Figure 4: Connection model for Asynchronous NT CS data

4.2 Limited set of GERAN Iu mode PLMN connection models

This subclause gives an overall overview on the PLMN connection models for circuit switched data services in GERAN Iu mode. The stage 2 description is given in 3GPP TS 43.051 [22]. For details concerning the PLMN connection models refer to 3GPP TS 43.010 [23].

4.2.1 Transparent data

Figure 5 shows the connection model for synchronous transparent CS data. In general all the user data bits are conveyed between the MT and the IWF as they are received from the TE. This implies that the RLC SDU/ Iu UP frame is transparent.

Figure 6 shows the connection model for asynchronous transparent CS data. The rate adaptation function RA0 from 3GPP TS 44.021 [18] (adapted to the RLC SDU size) is used for converting between asynchronous data and a synchronous bit stream. End-to-end flow control is not applicable in GERAN Iu mode, thus no status bits are conveyed over RAN/GERAN (see 3GPP TS 27.001 [14]).

Figure 5: Connection model for Synchronous T CS data

Figure 6: Connection model for Asynchronous T CS data

4.2.2 Non-transparent data

Figure 7 shows the connection model for asynchronous non-transparent CS data.

Figure 7: Connection model for Asynchronous NT CS data