5.15 RAN Information Management (RIM) procedures

23.4013GPPGeneral Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) accessRelease 18TS

5.15.1 General

The RAN Information Management (RIM) procedures provide a generic mechanism for the exchange of arbitrary information between applications belonging to the RAN nodes. The RAN information is transferred via the MME and SGSN core network node(s). In order to make the RAN information transparent for the Core Network, the RAN information is included in a RIM container that shall not be interpreted by the Core Network nodes.

The RIM procedures are optional both in the RAN and the CN nodes. For the Gb interface the use of RIM procedures is negotiated at start/restart of the Gb link. For the Iu interface there is no negotiation of using RIM procedures or not at Iu link start/restart.

The RAN information is transferred in RIM containers from the source RAN node to the destination RAN node by use of messages. Source and destination RAN nodes can be E-UTRAN, UTRAN or GERAN. Each message carrying the RIM container is routed and relayed independently by the core network node(s). Any relation between messages is transparent for the MME/SGSN, i.e. a request/response exchange between RIM applications, for example, is routed and relayed as two independent messages by the MME/SGSN.

The interfaces which will be used are the Gb, the Iu, the S1, Gn and the S3 interfaces. The RAN information in the RIM container shall be transparent for the Core Network. An MME or SGSN supporting the RIM procedures provides addressing, routing and relaying functions.

5.15.2 Addressing, routing and relaying

5.15.2.1 Addressing

All the messages used for the exchange of RAN information contain the addresses of the source and destination RAN nodes. A BSS is addressed by Routing Area Identity (RAI) + Cell Identity (CI) of one of its cells. An eNodeB is addressed by the Target eNodeB Identifier. An RNC is addressed by Global RNC-Id as defined in TS 23.003 [9].

5.15.2.2 Routing

The following description applies to all the messages used for the exchange of RAN information.

The source RAN node sends a message to its MME or SGSN including the source and destination addresses. The SGSN/MME uses the destination address to route the message encapsulated in a GTP message to the correct MME/SGSN via the S3 or Gn interface.

The MME/SGSN connected to the destination RAN node decides which RAN node to send the message to based on the destination address.

5.15.2.3 Relaying

The SGSN performs relaying between BSSGP messages, RANAP messages and GTP messages as described in TS 48.018 [42], TS 25.413 [22], TS 29.060 [14] and TS 29.274 [43]. The MME performs relaying between S1 and S3/Gn messages as described in TS 36.413 [36] and TS 29.274 [43] / TS 29.060 [14].

5.15.3 Applications using the RIM Procedures

The RAN node applications, which use the RIM procedures, are fully transparent for the MME and SGSN. These applications are described in RAN specifications. An example between E-UTRAN and GERAN is the Network Assisted Cell Change described in TS 48.018 [42], TS 25.413 [22] and TS 36.413 [36]. An example between E-UTRAN and UTRAN is the exchange of SON related information described in TS 36.413 [36]