16.10.6.2 Configuration

MBS broadcast can be received by UEs in RRC_IDLE, RRC_INACTIVE and RRC_CONNECTED state. A UE can receive the MBS configuration for broadcast session (e.g., parameters needed for MTCH reception) via MCCH in RRC_IDLE, RRC_INACTIVE and RRC_CONNECTED state. The parameters needed for the reception of MCCH are provided via System Information.

The following principles govern the MCCH structure:

• MCCH provides the list of all broadcast services with ongoing sessions transmitted on MTCH(s) and the associated information for broadcast session includes MBS session ID, associated G-RNTI scheduling information and information about neighbouring cells providing certain service on MTCH(s). MCCH content is transmitted within periodically occurring time domain windows, referred to as MCCH transmission window defined by MCCH repetition period, MCCH window duration and radio frame/slot offset;
• MCCH uses a modification period and MCCH contents are only allowed to be modified at each modification period boundary; a notification mechanism is used to announce the change of MCCH contents due to broadcast session start, modification or stop and due to neighbouring cell information modification;

NOTE: It is up to UE implementation to use the start and stop times in the USD to determine when to start monitoring the MCCH for the session the UE is interested in.

• When the UE receives an MCCH change notification, it acquires the updated MCCH in the same MCCH modification period where the change notification is sent.