Link layer control protocol implementation
The present invention relates to a link layer control protocol implementation in a communication system. To improve operative efficiency of the link layer control protocol implementation it is suggested to delay issuance of a retransmission request for a missing data unit during a retransmission delay time period. Therefore, according to the present invention a retransmission request is not issued immediately upon detection of a missing data unit. Therefore, the present invention avoids issuance of false alarm for the missing data unit when it is received during the retransmission delay period.
1. A method of implementing a link layer control protocol being operated on top of a medium access control layer protocol and providing services to an upper layer protocol, comprising the steps:
receiving data units from the medium access control protocol;
reordering data units provided by the medium access control layer protocol out of sequence;
reassembling data units in sequence for forwarding of service data units to the upper layer protocol;
comprising:
starting a first timer to delay issuance of a retransmission request for a missing data unit from the link layer control protocol triggered by detection of the missing data unit until expiry of the first timer; and
starting a second timer triggered by issuance of the retransmission request for the missing data unit from the link layer control protocol.
2. The method according to claim 1 , characterized in that the first timer is identical to the second timer.
3. The method according to claim 1 , characterized in that it comprises a step of starting a second timer triggered by detection of the missing data unit.
4. The method according to claim 1 , comprising a step of stopping the first timer upon receipt of the missing data unit from the medium access control protocol prior to expiry of the first timer, followed by reordering and reassembling of data units.
5. The method according to claim 1 , comprising a step of issuing the retransmission request for the missing data unit from the link layer control protocol triggered by expiry of the first timer.
6. The method according to claim 5 , comprising a step of restarting the first timer triggered by issuance of the retransmission request to delay issuance of a further retransmission request for the missing data unit from the link layer control protocol.
7. The method according to claim 1 , wherein the step of reordering data units and the step of reassembling data units is executed in consideration of successfully received data units upon termination of the retransmission process.
8. The method according to claim 7 , comprising a step of advancing a lower edge of a receiver window upon termination of the retransmission process without receipt of the missing data unit.
9. The method according to claim 7 , comprising a step of sending an acknowledgement status report with respect to the missing data unit to a transmitter of the missing data unit upon termination of the retransmission process without receipt of the missing data unit.
10. The method according to claim 1 , comprising a step setting the first timer to delay issuance of a retransmission request according to a maximum number of allowed retransmissions for the medium access control protocol.
11. The method according to claim 1 , comprising a step of setting the expiry of the second timer upon issuance of the retransmission request for the missing data unit from the link layer control protocol according to at least one service requirement of at least one application using services provided by the link layer control protocol.
12. A computer program product directly loadable into the internal memory of a communication receiver, comprising software code portions for performing the steps of claim 1 , when the product is run on a processor of the communication receiver.
13. An apparatus implementing a link layer control protocol being operated on top of a medium access control layer protocol and providing services to an upper layer protocol, comprising:
a data receiving unit adapted to receive data units from the medium access control protocol;
a data reordering unit adapted to reorder data units provided by the medium access control layer protocol out of sequence; and
a data reassembling unit adapted to reassemble data units in sequence for forwarding of service data units to the upper layer protocol;
comprising a first timer adapted to be started to delay issuance of a retransmission request for a missing data unit from the link layer control protocol triggered by detection of the missing data unit until expiry of the first timer and a second timer adapted to be started as triggered by issuance of the retransmission request for the missing data unit from the link layer control protocol.
14. The apparatus according to claim 13 , wherein the first timer is identical to the second timer.
15. The apparatus according to claim 13 , wherein the second timer is adapted to be started as triggered by detection of the missing data unit.
16. The apparatus according to claim 13 , wherein the first timer is adapted to stop timing operation upon receipt of the missing data unit from the medium access control protocol prior to expiry of the first timer.
17. The apparatus according to claim 13 , comprising a retransmission request issuing unit adapted to issue the retransmission request for the missing data unit from the link layer control protocol triggered by expiry of the first timer.
18. The apparatus according to claim 17 , wherein the first timer is adapted to restart timing operation as triggered by issuance of the retransmission request to delay issuance of a further retransmission request for the missing data unit from the link layer control protocol.
19. The apparatus according to claim 13 , wherein the data reordering unit and the data reassembling data unit are adapted execute data reordering and data reassembly in consideration of successfully received data units upon termination of the retransmission process.
20. The apparatus according to claim 19 , comprising a receiver window adaptation unit adapted to advance a lower edge of a receiver window upon termination of the retransmission process without receipt of the missing data unit.
21. The apparatus according to claim 19 , wherein the missing data completion unit is adapted to send an acknowledgement status report with respect to the missing data unit to a transmitter of the missing data unit upon termination of the retransmission process without receipt of the missing data unit.
22. The apparatus according to claim 13 , comprising a first timer setting unit adapted to set the first timer to delay issuance of a retransmission request according to a maximum number of allowed retransmissions for the medium access control protocol.
23. The apparatus according to claim 13 , comprising a second timer setting unit of setting the expiry of the second timer upon issuance of the retransmission request for the missing data unit from the link layer control protocol according to at least one service requirement of at least one application using services provided by the link layer control protocol.