Congestion control for delay sensitive applications

• US 9,485,184 B2
• Filed: 06/13/2013
• Issued: 11/01/2016
• Est. Priority Date: 03/05/2010
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Mehrotra, Sanjeev, Wynn, Tong L., Li, Jin, Sengupta, Sudipta
• Primary Examiner(s): Pham, Chi H
• Assistant Examiner(s): HOM, SHICK C
• Application Number:
  US13/917,441
• Publication Number:
  US 20130279338A1
• Time in Patent Office: 1,237 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H04L 47/22 Traffic shaping
• CPC Class Codes: H04L 47/2416 Real-time traffic
• CPC Class Codes: H04L 47/25 with rate being modified by the source upon detecting a change of network conditions
• CPC Class Codes: H04L 47/29 using a combination of thresholds
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes

Abstract

In various embodiments, methods and systems are disclosed for a hybrid rate plus window based congestion protocol that controls the rate of packet transmission into the network and provides low queuing delay, practically zero packet loss, fair allocation of network resources amongst multiple flows, and full link utilization. In one embodiment, a congestion window may be used to control the maximum number of outstanding bits, a transmission rate may be used to control the rate of packets entering the network (packet pacing), a queuing delay based rate update may be used to control queuing delay within tolerated bounds and minimize packet loss, and aggressive ramp-up/graceful back-off may be used to fully utilize the link capacity and additive-increase, multiplicative-decrease (AIMD) rate control may be used to provide fairness amongst multiple flows.

Claims

1. A method for transmitting data over a communications network, the method comprising:

upon determining that a number of queued data packets is below a predetermined threshold, transmitting data packets from a first computing device to a second computing device over the communications network in a predetermined order and at a transmission rate set at least in part based on congestion control implemented at the first computing device, the data packets including presentation data formatted according to a remote desktop protocol and the communications network including a lossy communication connection between the first computing device and the second computing device; and

adjusting the transmission rate of the data packets at the first computing device based upon a congestion level of the communications network, the congestion level based at least in part on received acknowledgements and absence of one or more received acknowledgements from the second computing device of the transmitted data packets.

2. The method of claim 1, wherein the congestion level is determined as a function of a packet queuing delay, a packet loss rate, and a one-way delay (OWD) trend.

3. The method of claim 2, wherein the packet loss rate is based on absence of one or more of the received acknowledgements from the second computing device within a retransmission time-out period.

4. The method of claim 2, wherein the packet queuing delay is based on an average of relative one way delay measurements of acknowledged packets during a predetermined time interval.

5. The method of claim 1, wherein the predetermined threshold comprises a predetermined queuing threshold, wherein the method further includes determining that the number of queued data packets is less than a predetermined queuing threshold and transmitting one of the data packets.

6. The method of claim 5, wherein the predetermined threshold comprises a predetermined queuing threshold, wherein the predetermined queuing threshold indicates a maximum quantity of data that can be queued and not transmitted over the communications network.

7. The method of claim 1, wherein one or more of the data packets includes forward error correction (FEC).

8. The method of claim 1, further comprising, when congestion is detected, reducing said rate of transmission until said congestion is no longer detected.

9. A computing system configured to transmit data over a communications network, the computing system comprising:

a programmable circuit;

a memory communicatively coupled to the programmable circuit and configured to store executable instructions that, upon execution by the programmable circuit, cause the computing system to perform a method including;

upon determining that a number of queued data packets is below a predetermined threshold, transmitting data packets to a second computing device over the communications network in a predetermined order and at a transmission rate set at least in part based on congestion control component, the data packets including presentation data formatted according to a remote desktop protocol and the communications network including a lossy communication connection between the first computing device and the second computing device; and

adjusting the transmission rate of the data packets at the first computing device based upon a congestion level of the communications network, the congestion level based at least in part on received acknowledgements and absence of one or more received acknowledgements from the second computing device of the transmitted data packets.

10. The computing system of claim 9, wherein the congestion level is determined as a function of a packet queuing delay, a packet loss rate, and a one-way delay (OWD) trend.

11. The computing system of claim 10, further comprising updating the transmission rate based on a zone classification.

12. The computing system of claim 11, wherein the zone classification is based on an average packet queuing delay estimate, packet loss, and the OWD trend.

13. The computing system of claim 10, wherein the packet loss rate is based on absence of an acknowledgement received from the second computing device within a retransmission time-out period.

14. The computing system of claim 10, wherein the packet queueing delay is based on an average of relative one way delay measurements of acknowledged packets during a predetermined time interval.

15. The computing system of claim 9, wherein adjusting the transmission rate includes reducing the rate of transmission until congestion is no longer detected.

16. A computer-readable storage device comprising computer-readable instructions, which, when executed, cause a computing system to perform a method for transmitting data over a communications network, the method comprising:

upon determining that a number of queued data packets is below a predetermined threshold, transmitting data packets from a first computing device to a second computing device over the communications network in a predetermined order and at a transmission rate set at least in part based on congestion control implemented at the first computing device, the data packets including presentation data formatted according to a remote desktop protocol and the communications network including a lossy communication connection between the first computing device and the second computing device; and

adjusting the transmission rate of the data packets at the first computing device based upon a congestion level of the communications network, the congestion level based at least in part on received acknowledgements and absence of one or more received acknowledgements from the second computing device of the transmitted data packets.

17. The computer-readable storage device of claim 16, wherein the congestion level is based on computing a number of packets lost during a sliding window to compute an estimate of the current loss rate.

18. The computer-readable storage device of claim 16, wherein the method further includes, when congestion is detected, reducing said rate of transmission until said congestion is no longer detected.

19. The computer-readable storage device of claim 16, wherein the congestion level is determined as a function of a packet queuing delay, packet loss rate, and one way delay (OWD) trend estimated based on acknowledgement packets.

20. The computer-readable storage device of claim 19, wherein the method further includes:

classifying network utilization level into one of three zones;

Zone 1;

OWD is not increasing and the average packet queuing delay is less than a predetermined delay threshold,

Zone 2;

OWD is not increasing, packet loss is below a predetermined loss threshold, and the average queuing delay is greater than the predetermined delay threshold but less than an upper threshold, and

Zone 3;

OWD is increasing, the average queuing delay is greater than the upper threshold or packet loss above a packet loss threshold is accompanied by average queuing delay above a queuing delay threshold.