8.43 MBMS RAB Release

25.4133GPPRelease 17TSUTRAN Iu interface Radio Access Network Application Part (RANAP) signalling

8.43.1 General

The purpose of the MBMS RAB Release procedure is to enable the UTRAN to request the release of an MBMS RAB. The MBMS RAB is defined for the PS domain only.

The procedure uses connection oriented signalling.

8.43.2 Successful Operation

Figure 56: MBMS RAB Release procedure. Successful operation.

The RNC initiates the procedure by generating a MBMS RAB RELEASE REQUEST message towards the CN. The MBMS RAB RELEASE REQUEST message is sent on the Iu connection related to the MBMS RAB to be released. The included cause value indicates the reason for the release, e.g. "RAB pre-empted", "Release due to UTRAN Generated Reason", "MBMS – No Data Bearer Necessary".

The CN should according to the MBMS RAB RELEASE REQUEST message initiate the release of all MBMS resources related to the Iu connection.

For MBMS Multicast service the Iu signalling connection should not be released.

The RNC may at reception of MBMS RAB RELEASE initiate release of the related MBMS bearer resources.

MBMS Broadcast service, interaction with MBMS Session Stop:

For MBMS Broadcast service the CN may initiate the appropriate release procedure for the MBMS Session related to the Iu signalling connection and invoke the MBMS Session Stop procedure.

8.43.3 Unsuccessful Operation

Figure 57: MBMS RAB RELEASE procedure. Unsuccessful operation.

If the CN node is not capable of correctly processing the request, the RNC shall be informed by the MBMS RAB RELEASE FAILURE message.

The MBMS RAB RELEASE FAILURE message shall inform the RNC about the reason for the unsuccessful operation with an appropriate cause value.

8.43.4 Abnormal Conditions

Not applicable.