Section: 5.9.4.2 Initiation
Content: An MBS capable UE in RRC_CONNECTED may initiate the procedure in several cases including upon successful connection establishment/resume, upon entering or leaving the broadcast service area, upon MBS broadcast session start or stop, upon change of interest, upon change of priority between MBS broadcast reception and unicast/multicast reception, upon change to a PCell providing SIB21 (i.e. where the SIB1 scheduling information contains SIB21), upon receiving SIB20 of an SCell via dedicated signalling, upon handover, and upon RRC connection re-establishment, upon change to a PCell providing nonServingCellMII in SIB1, upon starting or stopping reception of MBS broadcast service on a non-serving cell, upon change of CFR information or subcarrier spacing for MBS broadcast reception on a non-serving cell. If the UE does not have the CFR information and subcarrier spacing for MBS broadcast reception on a non-serving cell at the time it sends the MBS Interest Indication, the UE sends an MBS Interest Indication after it has acquired those information from the non-serving cell. Upon initiating the procedure, the UE shall: 1> if SIB21 is provided by the PCell; or 1> if nonServingCellMII is provided in SIB1 by the PCell: 2> ensure having a valid version of SIB21 for the PCell, if present; 2> if the UE did not transmit MBS Interest Indication since last entering RRC_CONNECTED state; or 2> if since the last time the UE transmitted an MBS Interest Indication, the UE connected to a PCell, neither providing SIB21 nor including nonServingCellMII in SIB1: 3> if the set of MBS broadcast frequencies of interest, determined in accordance with 5.9.4.3, is not empty: 4> set the contents of MBS Interest Indication according to 5.9.4.5 and initiate transmission of the MBSInterestIndication message; 2> else: 3> if the set of MBS broadcast frequencies of interest, determined in accordance with 5.9.4.3, is different from mbs-FreqList included in the last transmission of the MBS Interest Indication; or 3> if the set of MBS broadcast frequencies of interest for MBS broadcast reception on non-serving cell, determined in accordance with 5.9.4.3, is different from the list of MBS broadcast frequencies of interest for MBS broadcast reception on non-serving cell included in the last transmission of the MBS Interest Indication; or 3> if any of the subcarrier spacing and the CFR information for MBS broadcast reception on non-serving cell has changed since the last transmission of the MBS Interest Indication; or 3> if the subcarrier spacing and the CFR information for MBS broadcast reception on non-serving cell have been acquired from the non-serving cell which were not reported in the previous MBS Interest Indication; or 3> if the prioritisation of reception of all indicated MBS broadcast frequencies compared to reception of any of the established unicast bearers and multicast MRBs has changed since the last transmission of the MBS Interest Indication: 4> set the contents of MBS Interest Indication according to 5.9.4.5 and initiate transmission of the MBSInterestIndication message; NOTE: The UE may send MBS Interest Indication even when it is able to receive the MBS services it is interested in, i.e. to avoid that the network allocates a configuration inhibiting MBS broadcast reception. 3> else if SIB20 is provided for the PCell or for the SCell: 4> if since the last time the UE transmitted the MBS Interest Indication, the UE connected to a PCell not providing SIB20 and the UE was not provided with SIB20 for an SCell; or 4> if the set of MBS broadcast services of interest determined in accordance with 5.9.4.4 is different from mbs-ServiceList included in the last transmission of the MBS Interest Indication: 5> set the contents of MBS Interest Indication according to 5.9.4.5 and initiate the transmission of MBSInterestIndication message.