Methods and apparatuses for ul synchronization before performing cell change

Abstract

Embodiments of the present application relate to methods and apparatuses for uplink (UL) synchronization before performing cell change under a 3rd Generation Partnership Project (3GPP) 5G system or the like. According to an embodiment of the present application, a user equipment (UE) includes a transceiver and a processor coupled to the transceiver, and the processor is configured to receive a radio resource control (RRC) reconfiguration message associated with one or more candidate cells via the transceiver; perform one or more random access (RA) procedures to the one or more candidate cells for getting timing advance (TA), in response to reception of the RRC reconfiguration message; and switch from a source cell to one candidate cell within the one or more candidate cells, in response to reception of an indication associated with the one candidate cell via the transceiver from the source cell.

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