A method is presented for performing handover by a mobile terminal from a source base station to a target base station. The mobile terminal has a Radio Resource Control (RRC) layer and a Radio Link Control (RLC) layer. A handover command is received at the RRC layer of the mobile terminal. An indication associated with the handover command is received at the RLC layer of the mobile terminal. At least one RLC service data unit (SDU) from at least one protocol data unit (PDU) having a sequence number that is less than a higher edge of a window of the mobile terminal is reassembled at the RLC layer of the mobile terminal. The reassembled at least one RLC SDU to an upper layer of the mobile terminal is delivered at the RLC layer of the mobile terminal.