A method of wireless communication, comprising: allocating, from a single RLC entity, a plurality of RLC PDUs among a plurality of MAC entities (804, 806); sending the plurality of RLC PDUs to the plurality of MAC entities (804, 806) according to the allocation; receiving a first status PDU indicating a gap in sequence numbers of the RLC PDUs; and determining whether the gap is caused by a physical layer transmission failure or skew in accordance with the stored allocation; wherein the determining whether the gap is caused by a physical layer transmission failure or skew in accordance with the stored allocation comprises associating the sequence number of an RLC PDU corresponding to the gap with the MAC entity to which the RLC PDU was allocated, and comparing the sequence number with the last sequence number acknowledged for the corresponding MAC entity; on the condition that the gap is caused by a physical layer transmission failure, retransmitting the RLC PDU corresponding to the gap without delay; the method being characterised by: receiving a second status PDU indicating the gap in sequence numbers of the RLC PDUs; and determining whether the gap is caused by a physical layer transmission failure or skew comprising determining that the gap is caused by a physical layer transmission failure in accordance with a) determining that the gap does not correspond to a previous gap with a running retransmission delay timer, and b) determining that the RLC PDU corresponding to the gap has been previously retransmitted; and retransmitting the RLC PDU corresponding to the gap without delay, on the condition that the gap is determined to be caused by a physical layer transmission failure. allocating, from a single RLC entity, a plurality of RLC PDUs among a plurality of MAC entities (804, 806); sending the plurality of RLC PDUs to the plurality of MAC entities (804, 806) according to the allocation; receiving a first status PDU indicating a gap in sequence numbers of the RLC PDUs; and determining whether the gap is caused by a physical layer transmission failure or skew in accordance with the stored allocation; wherein the determining whether the gap is caused by a physical layer transmission failure or skew in accordance with the stored allocation comprises associating the sequence number of an RLC PDU corresponding to the gap with the MAC entity to which the RLC PDU was allocated, and comparing the sequence number with the last sequence number acknowledged for the corresponding MAC entity; on the condition that the gap is caused by a physical layer transmission failure, retransmitting the RLC PDU corresponding to the gap without delay; the method being characterised by: receiving a second status PDU indicating the gap in sequence numbers of the RLC PDUs; and determining whether the gap is caused by a physical layer transmission failure or skew comprising determining that the gap is caused by a physical layer transmission failure in accordance with a) determining that the gap does not correspond to a previous gap with a running retransmission delay timer, and b) determining that the RLC PDU corresponding to the gap has been previously retransmitted; and retransmitting the RLC PDU corresponding to the gap without delay, on the condition that the gap is determined to be caused by a physical layer transmission failure. receiving a second status PDU indicating the gap in sequence numbers of the RLC PDUs; and determining whether the gap is caused by a physical layer transmission failure or skew comprising determining that the gap is caused by a physical layer transmission failure in accordance with a) determining that the gap does not correspond to a previous gap with a running retransmission delay timer, and b) determining that the RLC PDU corresponding to the gap has been previously retransmitted; and retransmitting the RLC PDU corresponding to the gap without delay, on the condition that the gap is determined to be caused by a physical layer transmission failure.