Patent ID: 11943670
Assignee: SAMSUNG ELECTRONICS CO., LTD.
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A method performed by a user equipment (UE) in a wireless communication system, the method comprising:
receiving, from a source cell, a radio resource control (RRC) reconfiguration message indicating a handover;
configuring a medium access control (MAC) layer for a target cell based on the RRC reconfiguration message, wherein the RRC reconfiguration message includes information indicating a bearer is configured as a dual active protocol stack (DAPS) bearer,
performing, by the MAC layer for the target cell, a random access procedure on the target cell for a DAPS handover;
indicating, from the MAC layer for the target cell to an RRC layer, an indication of completion of the random access procedure based on completing the random access procedure on the target cell;
switching, by a packet data convergence protocol (PDCP) layer, uplink data for the bearer configured as the DAPS bearer based on receiving, from the RRC layer, a request for uplink data switching; and
transmitting, to the target cell, the uplink data,
wherein in case that the bearer is an acknowledged mode (AM) data radio bearer (DRB), and a first PDCP service data unit (SDU) of the uplink data is not confirmed a successful delivery by a radio link controller (RLC) layer associated with the source cell prior to the uplink data switching, at least one PDCP SDU of the uplink data is transmitted or retransmitted to an RLC layer associated with the target cell, in an ascending order of count values from a count value of the first PDCP SDU, and
wherein in case that the bearer is an unacknowledged mode (UM) DRB, and all PDCP SDUs of the uplink data have been processed by the PDCP layer and have not yet been submitted to a lower layer, the all PDCP SDUs of the uplink data are transmitted to the RLC layer associated with the target cell.