Patent ID: 7839858

Claim:
A data unit sender, comprising: a data unit buffer for holding data units of a communication protocol, a control unit arranged to control a transmission of said data units to a peer of said communication protocol, a processing of feedback messages received from said peer, a retransmission of said data units based on said feedback messages, and a management of said buffer, and said control unit as a sending peer of said communication protocol, where in accordance with said communication protocol said data units are arranged in a sequence and each sent data unit is identifiable by a sequence position identifier, and said feedback messages, using said sequence position identifiers, carry information on a receipt of said data units, said communication protocol providing for at least a first type and a second type of receipt information, said first type (RACK) of receipt information being indicative of a correct receipt of a data unit at a relay peer of said communication protocol, and said second type (ACK) of receipt information being indicative of a correct receipt of a data unit at a final destination peer of said communication protocol, said control unit being arranged to perform a first retransmission control procedure for a given data unit in said buffer that has been sent to the relay peer but for which no first type receipt information has been received, to perform a second retransmission control procedure for said given data unit if first type receipt information has been received for said given data unit, and to hold said given data unit in said buffer at least until having received said second type (ACK) of receipt information for said given data unit from the final destination peer.