Data transmission over a network having initially undetermined transmission capacity

• US 20060182016A1
• Filed: 03/08/2004
• Published: 08/17/2006
• Est. Priority Date: 03/19/2003
• Status: Active Grant

• Current Assignee: British Telecommunications PLC (BT Group PLC)
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: Walker, Matthew D, Urzaiz, Eduardo
• Granted Patent: US 7,761,901 B2
• Time in Patent Office: Days
• US Class Current: 370/208
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04N 21/2402 Monitoring of the downstream path of the transmission network, e.g. bandwidth available traffic monitoring in data switching networks H04L43/00; monitoring data switching networks utilization H04L43/0876
• CPC Class Codes: H04N 21/2662 Controlling the complexity of the video stream, e.g. by scaling the resolution or bitrate of the video stream based on the client capabilities

Abstract

Data to be transmitted over a network comprise a first part (perhaps audio) which is always to be transmitted and alternative second parts (perhaps video coded at different compression rates) of which one is to be chosen for transmission, depending on the current network capacity. In order to accommodate systems where (owing perhaps to the use of a congestion control mechanism such as TCP) the capacity available is initially undetermined, one firstly begins to transmit just the first part. When the network capacity becomes known (typically by monitoring the performance of the network in transmitting the first part), one of the alternative second parts is chosen and transmission of its commences. If desired this may initially be preferentially to, or to the exclusion of, further transmission of the first part.

Claims

1. A method of transmitting data over a network having initially undetermined transmission capacity, in which the data comprise a first part and at least two alternative second parts corresponding to respective different resolutions, for presentation at a receiving terminal simultaneously with the first part, comprising:

(a) transmitting at least an initial portion of the first part;

(b) receiving data indicative of the available transmission capacity;

(c) choosing among the alternative second parts, as a function of the data indicative of the available transmission capacity;

(d) transmitting the chosen second part and any remainder of the first part.

2. A method according to claim 1 including the step of generating said data indicative of the available transmission capacity by monitoring the transmission by the network of the said initial portion of the first part.

3. A method according to claim 1 in which, in an initial time period of step (d), transmission of a leading part of the chosen second part of an extent corresponding to the extent of the first part already transmitted is performed preferentially to, or to the exclusion of, further transmission of the first part.

4. A method according to claim 1 in which the first part is data representing an audio signal and the alternative second parts are alternative sets of video data, encoded at respective different compression rates, for presentation simultaneously with the audio data.

5. A method according to claim 1 in which the first part is the base layer data of layered coded video and the second part (s) are one or more enhancement layers of the layered coded video.

6. A method according to claim 1 in which the first part is text and the alternative second parts are alternative versions, having different resolutions, of a graphical image to be displayed alongside the text.

7. A method of transmitting data over a network having initially undetermined transmission capacity, in which the data comprise a first part and at least one second part, for presentation at a receiving terminal simultaneously with the first part, comprising:

(a) transmitting at least an initial portion of the first part;

(b) receiving data indicative of the available transmission capacity;

(c) choosing, as a function of the data indicative of the available transmission capacity, among the options of transmitting no second part, or one or more of the second parts;

(d) transmitting the chosen second part (s), if any, and the remainder of the first part.