Data transfer procedure for transferring data of a data sequence between a transmitting entity and a receiving entity

A data transfer procedure for transferring to a receiving entity data of a data sequence from a transmitting entity comprising a higher data handling layer and a lower data handling layer, the procedure comprising:

• transferring down from the higher data handling layer to the lower data handling layer a data unit of the data sequence, which data unit comprises at least one segment;
• transmitting on a transmission link from the lower data handling level of the transmitting entity each of the at least one segment for the receiving entity;
• receiving at the lower data handling level an acknowledgement of receipt of the at least one segment from the receiving entity;
• and wherein the higher data handling layer of the transmitting entity is arranged to retain the data unit until such time as an at least implied acknowledgement of receipt of earlier segments in the sequence is received from the receiving entity at the lower data handling level.

A communication system comprising:

• a transmitting entity for transmitting data of a data sequence, which transmitting entity comprises a higher data handling layer and a lower data handling layer;
• a receiving entity for receiving the data of the data sequence, which receiving entity comprises a higher data handling layer and a lower data handling layer;
• means for transferring down from the higher data handling layer of the transmitting entity to the lower data handling layer of the transmitting entity a data unit of the data sequence, which data unit comprises at least one segment;
• means for transmitting via a transmission link between the transmitting entity and the receiving entity each of the at least one segment from the lower data handling level of the transmitting entity to the lower data handling level of the receiving entity,
• means for sending an acknowledgement of receipt of the at least one segment from the lower data handling level of the receiving entity to the lower data handling level of the transmitting entity;
• means for transferring up the at least one segment from the lower data handling layer of the receiving entity to the higher data handling layer of the receiving entity in data sequence order;
• and wherein the higher data handling layer of the transmitting entity is arranged to retain the data unit until such time as an at least implied acknowledgement of receipt of earlier segments in the sequence is sent back from the receiving entity to the lower data handling level of the transmitting entity.

A transmitting entity for transmitting data of a data sequence for a receiving entity in a communications system, the transmitting entity comprising:

• a higher data handling layer;
• a lower data handling layer;
• means for transferring down from the higher data handling layer to the lower data handling layer a data unit of the data sequence, which data unit comprises at least one segment;
• means for transmitting on a transmission link from the lower data handling level each of the at least one segment for the receiving entity;
• means for receiving at the lower data handling level an acknowledgement of receipt of the at least one segment from the receiving entity;
• and
• means for causing the higher data handling layer to retain the data unit until such time as an at least implied acknowledgement of receipt of earlier segments in the sequence is received at the lower data handling level from the receiving entity.