ENHANCED ACKNOWLEDGEMENT AND RETRANSMISSION MECHANISM

• US 20140254351A1
• Filed: 03/08/2013
• Published: 09/11/2014
• Est. Priority Date: 03/08/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Newman, Richard E., Rajkotia, Purva R.
• Granted Patent: US 9,432,251 B2
• Time in Patent Office: Days
• US Class Current: 370/228
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04L 1/1864 ARQ related signaling H04L1/1607 takes precedence
• CPC Class Codes: H04L 1/1877 for semi-reliable protocols, e.g. for less sensitive applications like streaming video buffer level management for video bitstream control arrangements H04N21/44004
• CPC Class Codes: H04L 1/22 using redundant apparatus to increase reliability
• CPC Class Codes: H04L 2001/0096 Channel splitting in point-to-point links
• CPC Class Codes: H04L 41/0659 by isolating or reconfiguring faulty entities

Abstract

Protocol data units (PDUs) associated with a packet stream are transmitted with sequence numbers to support reordering and selective acknowledgement. A selective acknowledgement (SACK) message may be used to indicate at least one sequence number of a lost or corrupted PDU which was not properly received by the receiving device. Responsive to the SACK message, the lost or corrupted PDU is retransmitted via a different path of the network, different from the path used to transmit the original PDU. Lost or corrupted PDUs may not be retransmitted if the estimated retransmission delay is greater than a delay tolerance associated with the quality of service requirements of the application. Instead, a control message (i.e. “cut losses” message) may be transmitted to indicate that PDUs earlier than a particular sequence number will not be transmitted.

Claims

1. A method for transmitting from a first device to a second device, the method comprising:

transmitting, from a first device via at least a first path of a network to a second device, a series of protocol data units (PDUs) that include media access control (MAC) layer sequence numbers;

receiving a selective acknowledgement (SACK) message from the second device indicating at least one sequence number of a lost or corrupted PDU which was not properly received by the second device; and

retransmitting the lost or corrupted PDU via a second path of the network to the second device.

2. The method of claim 1, wherein the second path is lower latency relative to the first path.

3. The method of claim 1, further comprising, prior to said retransmitting the lost or corrupted PDU:

determining whether or not to retransmit particular lost or corrupted PDUs indicated in the SACK message based upon estimated retransmission delay and quality of service requirements of the series of PDUs.

4. The method of claim 3, further comprising:

refraining from retransmitting one or more of the particular lost or corrupted PDUs if the estimated retransmission delay is greater than a delay tolerance associated with the quality of service requirements of the series of PDUs.

5. The method of claim 3, further comprising:

transmitting a control message responsive to receiving the SACK message, the control message indicating that PDUs earlier than a particular sequence number will not be retransmitted.

6. The method of claim 1, further comprising:

transmitting a control indicator indicating that PDUs earlier than a particular sequence number will not be retransmitted.

7. The method of claim 6, wherein the control indicator is included with the retransmitted lost or corrupted PDU.

8. The method of claim 1, wherein the MAC layer sequence numbers are useable by the second device to deliver data from the PDUs to upper layers in the order that the PDUs were transmitted.

9. The method of claim 1, wherein the series of PDUs transmitted via the first path comprise a first subset of PDUs associated with a packet stream, the method further comprising:

transmitting, from the first device via a second path to the second device, a second subset of PDUs associated with the same packet stream, the second subset of PDUs also including MAC layer sequence numbers.

10. The method of claim 9, wherein the MAC layer sequence numbers for each of PDUs from the first subset of PDUs and the second subset of PDUs are unique among the PDUs for the packet stream.

11. The method of claim 9, wherein the SACK message indicates sequence numbers of lost or corrupted PDUs from both of the first subset of PDUs and the second subset of PDUs.

12. The method of claim 9, wherein said receiving the SACK message comprises receiving a first SACK message associated with acknowledgement feedback regarding the first subset of PDUs, the method further comprising:

receiving a second SACK message associated with acknowledgement feedback regarding the second subset of PDUs.

13. The method of claim 12, wherein the first SACK message and the second SACK message are received at the first device via a same feedback path from the second device to the first device.

14. The method of claim 1, wherein the MAC layer sequence numbers are included in the PDUs in a virtual local area network (VLAN) header that has been repurposed to include the MAC layer sequence numbers.

15. A first device comprising:

a network interface capable of being coupled to a network and configured to transmit via at least a first path of the network to a second device, a series of protocol data units (PDUs);

a sequence unit for maintaining media access control (MAC) layer sequence numbers associated with the series of PDUs;

a selective acknowledgement (SACK) and retransmit (SACK/Retransmit) controller configured to receive a SACK message from the second device indicating at least one sequence number of a lost or corrupted PDU which was not properly received by the second device and to retransmit the lost or corrupted PDU via a second path of the network to the second device.

16. The first device of claim 15, wherein the second path is lower latency relative to the first path.

17. The first device of claim 15, wherein the SACK/Retransmit controller is further configured to:

prior to retransmitting the lost or corrupted PDU, determine whether or not to retransmit particular lost or corrupted PDUs indicated in the SACK message based upon estimated retransmission delay and quality of service requirements of the series of PDUs.

18. The first device of claim 17, wherein the SACK/Retransmit controller is further configured to:

refrain from retransmitting one or more of the particular lost or corrupted PDUs if the estimated retransmission delay is greater than a delay tolerance associated with the quality of service requirements of the series of PDUs.

19. The first device of claim 17, wherein the SACK/Retransmit controller is further configured to:

transmit a control message responsive to receiving the SACK message, the control message indicating that PDUs earlier than a particular sequence number will not be retransmitted.

20. The first device of claim 15, wherein the SACK/Retransmit controller is further configured to:

transmit a control indicator indicating that PDUs earlier than a particular sequence number will not be retransmitted.

21. The first device of claim 20, wherein the control indicator is included with the retransmitted lost or corrupted PDU.

22. The first device of claim 15, wherein the MAC layer sequence numbers are useable by the second device to deliver data from the PDUs to upper layers in the order that the PDUs were transmitted.

23. The first device of claim 15, wherein the series of PDUs transmitted via the first path comprise a first subset of PDUs associated with a packet stream, and wherein the SACK/Retransmit controller is further configured to:

transmit, from the first device via a second path to the second device, a second subset of PDUs associated with the same packet stream, the second subset of PDUs also including MAC layer sequence numbers.

24. The first device of claim 23, wherein the MAC layer sequence numbers for each of PDUs from the first subset of PDUs and the second subset of PDUs are unique among the PDUs for the packet stream.

25. The first device of claim 23, wherein the SACK message indicates sequence numbers of lost or corrupted PDUs from both of the first subset of PDUs and the second subset of PDUs.

26. The first device of claim 23, wherein said receiving the SACK message comprises receiving a first SACK message associated with acknowledgement feedback regarding the first subset of PDUs, and wherein the SACK/Retransmit controller is further configured to:

receive a second SACK message associated with acknowledgement feedback regarding the second subset of PDUs.

27. The first device of claim 26, wherein the first SACK message and the second SACK message are received at the first device via a same feedback path from the second device to the first device.

33. The first device of claim 15, wherein the series of PDUs transmitted via the first path comprise a first subset of PDUs associated with a packet stream, and wherein the communication processor is further configured to:

transmit, from the first device via a second path to the second device, a second subset of PDUs associated with the same packet stream, the second subset of PDUs also including MAC layer sequence numbers.

28. A non-transitory computer readable medium storing computer program code, the computer program code comprising instructions which when executed by a processor of a first device causes the first device to:

transmit, from a first device via at least a first path of a network to a second device, a series of protocol data units (PDUs) that include media access control (MAC) layer sequence numbers;

receive a selective acknowledgement (SACK) message from the second device indicating at least one sequence number of a lost or corrupted PDU which was not properly received by the second device; and

retransmit the lost or corrupted PDU via a second path of the network to the second device.

29. The non-transitory computer readable medium of claim 28, wherein the computer program code further comprises instructions which when executed by the processor of the first device causes the first device to:

prior to retransmitting the lost or corrupted PDU, determine whether or not to retransmit particular lost or corrupted PDUs indicated in the SACK message based upon estimated retransmission delay and quality of service requirements of the series of PDUs.

30. The non-transitory computer readable medium of claim 28, wherein the computer program code further comprises instructions which when executed by the processor of the first device causes the first device to:

refrain from retransmitting one or more of the particular lost or corrupted PDUs if the estimated retransmission delay is greater than a delay tolerance associated with the quality of service requirements of the series of PDUs.

31. The non-transitory computer readable medium of claim 28, wherein the computer program code further comprises instructions which when executed by the processor of the first device causes the first device to:

transmit a control message responsive to receiving the SACK message, the control message indicating that PDUs earlier than a particular sequence number will not be retransmitted.

32. The non-transitory computer readable medium of claim 28, wherein the computer program code further comprises instructions which when executed by the processor of the first device causes the first device to:

transmit a control indicator indicating that PDUs earlier than a particular sequence number will not be retransmitted.

34. An apparatus for transmitting information from a first device via a network to a second device, the apparatus comprising:

means for transmitting, from a first device via at least a first path of a network to a second device, a series of protocol data units (PDUs) that include media access control (MAC) layer sequence numbers;

means for receiving a selective acknowledgement (SACK) message from the second device indicating at least one sequence number of a lost or corrupted PDU which was not properly received by the second device; and

means for retransmitting the lost or corrupted PDU via a second path of the network to the second device.

35. The apparatus of claim 34, further comprising:

means for determining, prior to said retransmitting the lost or corrupted PDU, whether or not to retransmit particular lost or corrupted PDUs indicated in the SACK message based upon estimated retransmission delay and quality of service requirements of the series of PDUs.

36. The apparatus of claim 35 further comprising:

means for refraining from retransmitting one or more of the particular lost or corrupted PDUs if the estimated retransmission delay is greater than a delay tolerance associated with the quality of service requirements of the series of PDUs.

37. The apparatus of claim 35, further comprising:

means for transmitting a control message responsive to receiving the SACK message, the control message indicating that PDUs earlier than a particular sequence number will not be retransmitted.