Patent ID: 8462633

Claim:
A method for processing data in a mobile communication system, the method comprising: receiving data protocol data units (PDUs) from a transmitting side, wherein each of the data PDUs has a header comprising a sequence number; for each received data PDU having a sequence number which is within a range of a receiving window, storing the received data PDU in a buffer and delivering successfully received service data units (SDUs) to a higher layer that is stored in the buffer in the order of increasing values of the sequence number; receiving a control message for controlling a start value of the receiving window, from the transmitting side, the control message including information related to a first PDU for which an acknowledgment is expected; passing at least one successfully received SDU stored in the buffer with a sequence number which is lower than a new start value of the receiving window, as indicated by the control message, up to a higher layer; and setting the new start value of the receiving window to a next value of a sequence number of a last SDU that was passed up to the higher layer.