5.1 GPRS Access Interfaces and Reference Points

23.0603GPPGeneral Packet Radio Service (GPRS)Release 17Service descriptionStage 2TS

Each PLMN has two access points to GPRS services, the radio interface (labelled Um in A/Gb mode and Uu in Iu mode) used for mobile access and the R reference point used for origination or reception of messages. The R reference point for the MSs is defined in TS 27.060 [17].

An interface differs from a reference point in that an interface is defined where specific information is exchanged and needs to be fully recognised.

There is an inter PLMN interface called Gp or S8, respectively that connects two independent GPRS packet domain networks for message exchange.

There is also a PLMN to packet data network reference point called Gi or SGi, respectively. Gi and SGi are defined in TS 29.061 [27].

Figure 1: GPRS Access Interfaces and Reference Points

There may be more than a single network interface to several different packet data networks. These networks may both differ in ownership as well as in communications protocol (e.g. TCP/IP etc.). The network operator defines and negotiates interconnection with each interconnected packet data network.