CONGESTION CONTROL IN DATA NETWORKS

• US 20150085648A1
• Filed: 09/24/2013
• Published: 03/26/2015
• Est. Priority Date: 09/24/2013
• Status: Abandoned Application

• Current Assignee: National University of Ireland, Maynooth
• Original Assignee: National University of Ireland, Maynooth
• Inventors: Leith, Douglas
• Application Number:
  US14/035,228
• Publication Number:
  US 20150085648A1
• Time in Patent Office: Days
• US Class Current: 370/230
• CPC Class Codes: H04L 47/12 Avoiding congestion; Recovering from congestion

Abstract

A method of modifying transmission of packets over a network path comprises operating a processor to: transmit packets over the network path; determine, based on a number of unacknowledged packets transmitted over the network path, whether a congestion event has occurred, wherein an unacknowledged packet is a transmitted packet for which no acknowledgement has been received; and responsive to detecting a congestion event, operating a processor to modify the number of unacknowledged packets transmitted by a multiplicative factor β_i, wherein the multiplicative factor β_i is proportional to a ratio of a first time value to a second time value, the first time value being indicative of a minimum time required for a packet to be transmitted over the network path and the second time value being indicative of a current time required for a packet to be transmitted over the network path.

Claims

1. A method of modifying transmission of packets over a network path, the method comprising operating a processor to:

transmit packets over the network path;

determine, based on a number of unacknowledged packets transmitted over the network path, whether a congestion event has occurred, wherein an unacknowledged packet is a transmitted packet for which no acknowledgement has been received; and

responsive to detecting a congestion event, operating a processor to modify the number of unacknowledged packets transmitted by a multiplicative factor β

_i, wherein the multiplicative factor β

_i is proportional to a ratio of a first time value to a second time value, the first time value being indicative of a minimum time required for a packet to be transmitted over the network path and the second time value being indicative of a current time required for a packet to be transmitted over the network path.

2. The method of claim 1, wherein responsive to determining that a congestion event has not occurred, the method further comprises operating a processor to:

modify the number of unacknowledged packets transmitted over the network path by an additive factor α

_i.

3. The method of claim 2, wherein responsive to determining that a congestion event has not occurred, the method further comprises operating a processor to determine an elapsed period of time since detection of a congestion event.

4. The method of claim 3, further comprising operating a processor to determine the additive factor α

_i in accordance with the elapsed period of time since detection of a congestion event.

5. The method of claim 4, wherein when the elapsed period of time since detection of a congestion event is less than a threshold value, the additive factor α

_i is equal to unity.

6. The method of claim 5, wherein operating a processor to determine the additive factor α

_i in accordance with the elapsed period of time since detection of a congestion event comprises operating the processor to increase the additive factor α

_i as a function of the congestion epoch timer.

7. The method of claim 5, wherein operating a processor to determine the additive factor α

_i in accordance with the elapsed period of time since detection of a congestion event comprises operating the processor to increase the additive factor α

_i at intervals during a period in which the congestion epoch timer is greater than a threshold value.

8. The method of claim 1, wherein the processor is operated to detect a congestion event if one or more of:

(i) a packet loss is detected; and

(ii) an estimated time for a packet to be transmitted over the network path is greater than a predefined threshold value.

9. The method of claim 1, further comprising operating a processor to:

estimate, at predefined intervals, a round-trip delay between a time of transmitting a packet over the network path and a time of receiving an acknowledgement that the packet has been received; and

set the second time value to the estimated round-trip delay.

10. The method of claim 9, wherein the first time value is an estimate of a minimum round-trip delay between a time of transmitting a packet over the network path and a time of receiving an acknowledgement that the packet has been received;

and

the multiplicative factor β

_i is equal to a ratio of the first time value to the second time value.

11. The method of claim 1, further comprising operating a processor to:

estimate, at predefined intervals, a one-way delay time between a time at which the packet is transmitted over the network path and a time at which the packet is received by a receiver; and

set the second time value to the estimated one-way delay time.

12. The method of claim 11, wherein the first time value is an estimate of a minimum one-way delay time between a time at which a packet is transmitted over the network path and a time at which the packet is received by a receiver;

and

the multiplicative factor β

_i is equal to a ratio of the first time value to the second time value.

13. The method of claim 1, wherein the second value is an exponentially weighted moving average of estimated packet delays.

14. The method of claim 1, wherein the network is a wireless network.

15. The method of claim 1, wherein the method is implemented as part of a transport layer protocol.

16. The method of claim 1, wherein the method is implemented as part of a network tunnel protocol.

17. The method of claim 1, wherein the method is implemented as part of a network proxy protocol.

18. The method of claim 1, wherein operating a processor to transmit packets over the network path comprises operating the processor to:

encode the packets using error correction coding; and

transmit the encoded packets.

19. The method of claim 18, wherein operating a processor to encode the packets using error coding and to transmit the encoded packets comprises operating the processor to:

transmit a number of information packets;

generate an encoded packet based on the information packets; and

transmit the encoded packet.

20. The method of claim 19, wherein operating a processor to generate the encoded packet comprises operating a processor to generate the encoded packet using Reed-Solomon encoding.

21. The method of claim 19, wherein operating a processor to generate the encoded packet comprises operating a processor to generate the encoded packet using linear encoding.

22. The method of claim 21, further comprising operating a processor at a receiver to:

receive the encoded packets; and

decode the received packets using Gaussian elimination decoding.

23. (canceled)

24. (canceled)

25. (canceled)

26. A transmitter for sending packets over a network path, wherein the transmitter comprises processing circuitry configured to:

transmit packets over the network path;

determine, based on a number of unacknowledged packets transmitted over the network path, whether a congestion event has occurred, wherein an unacknowledged packet is a transmitted packet for which no acknowledgement has been received; and

responsive to detecting a congestion event, operating a processor to modify the number of unacknowledged packets transmitted by a multiplicative factor β

_i, wherein the multiplicative factor β

_i is proportional to a ratio of a first time value to a second time value, the first time value being indicative of a minimum time required for a packet to be transmitted over the network path and the second time value being indicative of a current time required for a packet to be transmitted over the network path.

27. (canceled)

28. (canceled)

29. (canceled)

30. (canceled)

31. (canceled)

32. (canceled)

33. (canceled)

34. (canceled)

35. (canceled)

36. (canceled)

37. A non-transitory computer-readable medium comprising instructions which when executed cause a processor to:

transmit packets over the network path;

determine, based on a number of unacknowledged packets transmitted over the network path, whether a congestion event has occurred, wherein an unacknowledged packet is a transmitted packet for which no acknowledgement has been received; and

responsive to detecting a congestion event, operating a processor to modify the number of unacknowledged packets transmitted by a multiplicative factor β

_i, wherein the multiplicative factor β

_i is proportional to a ratio of a first time value to a second time value, the first time value being indicative of a minimum time required for a packet to be transmitted over the network path and the second time value being indicative of a current time required for a packet to be transmitted over the network path.