Patent ID: 8000256

Claim:
A method for transmitting data of a Radio Link Control (RLC) layer in a mobile communication system, the method comprising the steps of: transmitting a Service Data Unit (SDU), which has been transferred from an upper layer, through at least one Protocol Data Unit (PDU); starting a first timer when the SDU has been transferred; discarding the SDU, when acknowledgements for all of the at least one PDU associated with the SDU have been received by an expiration time of the first timer; requesting a receiving side to transmit a status report about a data reception status and starting a second timer, when the acknowledgements for all of the at least one PDU associated with the SDU have not been received by the expiration time of the first timer; receiving the status report, and retransmitting a non-acknowledged PDU based on the status report; and discarding the SDU, when the second timer has expired.