Section: 5.10.3 MRB configuration 5.10.3.1 General
Content: The multicast MRB configuration procedure is used by the UE in RRC_INACTIVE state to configure PDCP, RLC, MAC entities and the physical layer upon PTM configuration update and moving to a cell providing SIB24. The UE may perform multicast MRB modification or release/establishment when PTM configuration is updated via MCCH or when it moves to a cell where the PDCP COUNT of the corresponding multicast MRB is not synchronized within the RNA. The UE may perform multicast MRB modification when it moves to a cell where the PDCP COUNT of the corresponding multicast MRB is synchronized within the RNA. The UE resets MAC upon cell-reselection. NOTE: How to perform modification of a multicast MRB which is already configured in the UE is left to UE implementation. Upon moving to a cell where the PDCP COUNT of a multicast MRB is not synchronized, an indication is sent to the lower layer to inform the PDCP COUNT non-synchronization of the corresponding multicast MRB. Upon transition from RRC_CONNECTED to RRC_INACTIVE in the same cell, the UE can continue using the multicast MRBs used in RRC_CONNECTED.