Patent ID: 8400982

Claim:
A method of processing data by a source base station in a mobile communication system, the method comprising: transmitting a first data block, to a user equipment, the first data block including a full header; transmitting, to the user equipment, at least one second data block on which header compression was performed based on the first data block; and forwarding the first data block and the at least one second data block to a target base station during a handover procedure, in order for the target base station to re-transmit the first data block and the at least one second data block to the user equipment, when the first data block was not correctly received by the user equipment and the at least one second data block was correctly received by the user equipment, wherein the forwarding the first data block and the at least one second data block to the target base station is determined by a Packet Data Convergence Protocol (PDCP) layer checking a status of at least one second block received from the user equipment, and wherein the status of at least one second block is set to indicate negative acknowledgement by the PDCP layer, when the PDCP layer receives information indicating the first data block was not correctly received by the user equipment.