Improved congestion response

Patent metadata

Field	Value
Publication number	US-2021297358-A1
Application number	US-201917266337-A
Country	US
Kind code	A1
Filing date	Aug 8, 2019
Priority date	Aug 8, 2018
Publication date	Sep 23, 2021
Grant date	—

Abstract

In examples of the present invention, during delivery of content, the round trip times for each delivered data packet are measured and the congestion window used for delivery is adjusted accordingly. The congestion window is set to a relatively high value when the round trip times are relatively low, and set to a relatively low value when the round trip times are relatively high.

First claim

1 . A method of delivering content from a server to a client over a network, said content comprising a plurality of temporal segments having an associated time available for delivery, and each temporal segment comprising a plurality of data packets, said method comprising:
a) delivering a first portion of a segment from the server to the client; b) measuring a plurality of round trip times associated with delivery of at least the first portion; c) determining a current round trip time, a central round trip time, a lower round trip time, and an upper round trip time from the plurality of round trip times; d) calculating a required congestion window size needed to deliver the data remaining in the segment within the time available to deliver the data remaining in the segment, wherein the required congestion window size is dependent on the central round trip time; e) calculating a modified congestion window size, where the modified congestion window size falls within a range set around the required congestion window size, and where the modified congestion window size is relatively high when the current round trip time is close to the lower round trip time, and the modified congestion window size is relatively low when the current round trip time is close to the upper round trip time; f) delivering further data from the remainder of the segment using the modified congestion window size from the server to the client; g) measuring a plurality of round trip times associated with delivery of the further data from the remainder of the segment; and h) repeating steps c) to f) using at least the plurality of round trip times from step g).

2 . A method as set out in claim 1 , wherein the current round trip time is the round trip time associated with delivery of the most recent packet.

3 . A method as set out in claim 1 , wherein the modified congestion window size falls between a minimum congestion window size and a maximum congestion window size that are set as a percentage offset from the required congestion window size.

4 . A method as set out in claim 1 , wherein the lower round trip time is the lowest value of the measured round trip times, and the higher round trip time is the highest value of the measured round trip times.

5 . A method as set out in claim 1 , wherein the modified congestion window size, CWND modified , is given by:

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where CWND min is the minimum congestion window size, CWND max is the maximum congestion window size, RTT high is the higher round trip time, RTT low is the lower round trip time, and RTT current is the current round trip time.

6 . A server for delivering content over a network to a client, said content comprising a plurality temporal segments having an associated time available for delivery, and each temporal segment comprising a plurality of data packets, said adapted in operation to:
a) deliver a first portion of a segment from the server to the client; b) measure a plurality of round trip times associated with delivery of at least the first portion; c) determine a current round trip time, a central round trip time, a lower round trip time, and an upper round trip time from the plurality of round trip times; d) calculate a required congestion window size needed to deliver the data remaining in the segment within the time available to deliver the data remaining in the segment, wherein the required congestion window size is dependent on the central round trip time; e) calculate a modified congestion window size, where the modified congestion window size falls within a range set around the required congestion window size, and where the modified congestion window size is relatively high when the current round trip time is close to the lower round trip time, and the modified congestion window size is relatively low when the current round trip time is close to the upper round trip time; f) deliver further data from the remainder of the segment using the modified congestion window size fro

Assignees

• British Telecomm

Inventors

• Humeida Yousif
• Appleby Stephen
• Nilsson Michael

Classifications

• H04L47/283 Primary

  in response to processing delays, e.g. caused by jitter or round trip time [RTT] · CPC title

• H04L47/27

  Evaluation or update of window size, e.g. using information derived from acknowledged [ACK] packets · CPC title

• H04L43/0864

  Round trip delays · CPC title