A UE in a wireless communication system is provided. The UE comprises at least one processor configured to identify a DTTC including at least one of a first periodicity, a duration of a first transmission window, or a first timing offset of the first transmission window, wherein the DTTC is identified for the DSCH or RLM in a serving cell, and identify a DMTC including at least one of a second periodicity, a duration of a second transmission window, or a second timing offset of the second transmission window, wherein the DMTC is identified for RRM measurement based on the DSCH. The UE further comprises a transceiver operably connected to the processor, the transceiver configured to receive, from a BS, at least one DSCH from a set of DSCH over unlicensed downlink channels based on the identified DTTC, wherein the received at least one DSCH includes a SS/PBCH block.