27 series - R interface protocols and terminal adaptation functions
The mobile equipment (ME) contains all the components of the UE apart from the UICC. In voice mobiles, the ME is usually a single device, but in the case of data terminals, the functions are often split in two:
- MT: This handles radio transmission and reception (eg a plug-in UMTS card for a laptop).
- TE: This handles data input and output (eg the laptop itself).
The 27 series covers the R interface between the MT and the TE, and the terminal adaptation function (TAF) that the MT requires in order to communicate with the TE. The R interface is not fully specified by 3GPP: instead, it can use a variety of open standards such as IrDA or PCMCIA. A few issues are specified here, however:
- The mechanisms that are used to transfer CS data streams, PS data streams and SMS messages between the TE and the MT.
- A set of AT commands, which are used to exchange signalling messages between the TE and the MT.
- The functions that the MT requires in order to transfer signalling messages and data between the R interface and the radio interface.
- A multiplexer protocol, which allows the simultaneous transfer of several different data streams over a single serial link.
|IrDA||Infrared data association|
|PCMCIA||Personal computer memory card international association|
|SMS||Short message service|
|TAF||Terminal adaptation function|
|UICC||Universal integrated circuit card|