| CPC H04W 36/0033 (2013.01) [H04W 36/0055 (2013.01); H04W 36/185 (2023.05)] | 14 Claims |

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1. A method performed by a user equipment (UE) in a wireless communication system, the method comprising:
receiving, from a source base station, a first radio resource control (RRC) reconfiguration message including configuration information indicating reconfiguration with sync, identification information of a bearer, and dual active protocol stack (DAPS) configuration information indicating that the bearer is configured as a DAPS bearer;
reconfiguring a packet data convergence protocol (PDCP) entity of the UE for the bearer based on the first RRC reconfiguration message;
in case that a random access to the target base station is successfully completed, requesting, by an RRC entity of the UE, the PDCP entity to switch uplink data;
in case that the uplink data switching being requested, identifying whether a PDCP protocol data unit (PDU) is a PDCP data PDU or a PDCP control PDU;
in case that the PDCP PDU is the PDCP control PDU, identifying whether the PDCP control PDU is associated with the source base station or the target base station; and
in case that the PDCP control PDU is associated with the source base station, submitting, by the PDCP entity, the PDCP control PDU to a radio link control (RLC) entity associated with the source base station.
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