11.3.7a Signalling procedures for the user plane

3GPP43.069Release 16Stage 2TSVoice Broadcast Service (VBS)

11.3.7a.1 Broadcast call re-establishment by the BSS

The MSC and BSC negotiate during the setup of a voice broadcast call whether broadcast call re-establishment by the BSS is supported by both entities.

If broadcast call re-establishment by the BSS is supported by both entities or the network uses a transmission architecture with A-interface link sharing, the following procedures apply:

i) If the BSS needs to release the broadcast call channel in a cell due to an equipment failure or another BSS-generated reason (e.g. preemption), the BSS shall inform the MSC of the failure with a VBS Assignment Status message.

The terrestrial resource for the broadcast call channel is not released by the MSC.

ii) When the condition that caused the failure is subsequently removed, the BSS shall re-allocate a radio resource for the broadcast call channel and inform the MSC of the recovery with a VBS Assignment Status message.

iii) If A-interface link sharing is used, each of the VBS ASSIGNMENT STATUS messages in item (i) and (ii) shall be sent after expiry of timer Tast.

Otherwise, if broadcast call re-establishment by the BSS is not supported by both entities and the network does not use a transmission architecture with A-interface link sharing, the following procedures apply:

i) If the BSS needs to release the broadcast call channel in a cell due to an equipment failure or another BSS-generated reason (e.g. preemption), the BSS shall inform the MSC of the failure with a Clear Request message.

ii) The MSC shall then initiate the clearing of the radio and terrestrial resources for the broadcast call channel. If supported, the MSC may retry the VBS Assignment procedure for the cell, depending on the reason for release.

Broadcast call re-establishment by the BSS does not apply to the dedicated link of the originating service subscriber, i.e. if the BSS needs to release the dedicated channel of the originating service subscriber due to an equipment failure or another BSS-generated reason (e.g. preemption), the BSS shall inform the MSC of the failure with a Clear Request message. The MSC shall then initiate release of the voice broadcast call.