METHOD AND DEVICE FOR TRANSMITTING DATA

• US 20090097483A1
• Filed: 10/06/2008
• Published: 04/16/2009
• Est. Priority Date: 10/15/2007
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Henocq, Xavier, Maze, Frederic
• Granted Patent: US 8,462,778 B2
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 41/0896 Bandwidth or capacity management, i.e. automatically increasing or decreasing capacities flow or congestion control using dynamic resource allocation, e.g. in-call renegotiation, H04L47/76
• CPC Class Codes: H04L 41/147 for predicting network behaviour
• CPC Class Codes: H04L 43/0864 Round trip delays
• CPC Class Codes: H04L 43/16 Threshold monitoring
• CPC Class Codes: H04L 47/11 Identifying congestion
• CPC Class Codes: H04L 47/18 End to end
• CPC Class Codes: H04L 47/25 with rate being modified by the source upon detecting a change of network conditions
• CPC Class Codes: H04L 47/283 in response to processing delays, e.g. caused by jitter or round trip time [RTT]
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/65 Network streaming protocols, e.g. real-time transport protocol [RTP] or real-time control protocol [RTCP]
• CPC Class Codes: H04L 65/80 Responding to QoS

Abstract

The method of transmitting data packets associated with an importance level comprises a step (305) of estimating available rate on the network. In case a variation is detected in estimated available rate greater than a first predetermined value, determination is made (309-317) of whether there is an increase in the round trip time on said network that is greater than a second predetermined value. If yes, the data packets are transmitted (319-325) at a rate lower than the estimated available rate.

In embodiments, in case a variation is detected in estimated available rate greater than a first predetermined value and before the step of detecting an increase in the round trip time, a step (307) is carried out of transmitting packets of lower importance level than the average of said importance levels by using the current estimated available rate and the round trip time is determined on the basis of the sending of those packets.

Claims

1. A method of transmitting data packets over a network, each data packet being associated with an importance level from among at least two importance levels, comprising a step of estimating rate available on the network, that comprises a step of detecting a variation in estimated available rate and, in case a variation in estimated available rate is detected that is greater than a first predetermined value:

a step of detecting an increase in the round trip time on said network greater than a second predetermined value and

in case an increase in the round trip time is detected, a step of transmitting data packets at a rate lower than the estimated available rate.

2. A method according to claim 1, wherein, in case a variation is detected in estimated available rate greater than a first predetermined value and before the step of detecting an increase in the round trip time, a step is carried out of transmitting packets of lower importance level than the average of said importance levels.

3. A method according to claim 2, wherein, during the step of transmitting packets of importance level lower than the average importance level, the current estimated available rate is used.

4. A method according to claim 2, wherein, during the step of detecting an increase in the round trip time, the round trip time is determined on the basis of the sending of packets transmitted during the step of transmitting packets of lower importance level.

5. A method according to claim 1, wherein, during the step of transmitting data packets at a lower rate than the estimated available rate, if the variation in estimated available rate is an increase, the estimated available rate preceding the step of detecting the variation in estimated available rate is used.

6. A method according to claim 1, wherein, during the step of transmitting data packets at a lower rate than the estimated available rate, if the variation in estimated available rate is a reduction, a fraction of the current estimated available rate is used.

7. A method according to claim 1, wherein, during the step of transmitting data packets at a lower rate than the estimated available rate, a part of the current estimated available rate is used to transmit data packets and a part of the current estimated rate is used to transmit redundancy data packets.

8. A method according to claim 7, wherein the redundancy data are FEC data (FEC being the acronym for “

Forward Error Correction”

).

9. A method according to claim 1, that comprises a step of congestion control implementing TFRC (acronym for “

TCP-Friendly Rate Control”

) to provide said estimation of available rate.

19. A computer program that can be loaded into a computer system, said program containing instructions enabling the implementation of the method according to claim 1.

20. A removable or non-removable carrier for computer or microprocessor readable information, storing instructions of a computer program, characterized in that it makes it possible to implement the method according to claim 1.

10. A device for transmitting data packets over a network, each data packet being associated with an importance level from among at least two importance levels, comprising a means for estimating rate available on the network, that comprises a means for detecting a variation in estimated available rate that is greater than a first predetermined value and a transmission means that is adapted, in case of detection of a variation in estimated available rate:

to detect an increase in the round trip time greater than a second predetermined value on said network and

in case an increase in the round trip time is detected, to transmit data packets at a rate lower than the estimated available rate.

11. A device according to claim 10, that further comprises a means for transmitting packets of lower importance level than the average of said importance levels, in case a variation is detected in estimated available rate greater than a first predetermined value and before the means for detecting a variation in estimated available rate detects an increase in the round trip time.

12. A device according to claim 11, wherein the means for transmitting packets of importance level lower than the average importance level is adapted to use the current estimated available rate.

13. A device according to claim 11, wherein the means for detecting an increase in the round trip time is adapted to determine the round trip time on the basis of the sending of packets transmitted by the means for transmitting packets of lower importance level.

14. A device according to claim 10, wherein the means for transmitting data packets at a lower rate than the estimated available rate is adapted, if the variation in estimated available rate is an increase, to use the estimated available rate preceding the detection of the variation in estimated available rate by the means for detecting the variation in estimated available rate.

15. A device according to claim 10, wherein the means for transmitting data packets at a lower rate than the estimated available rate is adapted, if the variation in estimated available rate is a reduction, to use a fraction of the current estimated available rate.

16. A device according to claim 10, wherein the means for transmitting data packets at a lower rate than the estimated available rate to use a part of the current estimated available rate to transmit data packets and to use a part of the current estimated rate to transmit redundancy data packets.

17. A device according to claim 16, wherein the redundancy data are FEC data (FEC being the acronym for “

Forward Error Correction”

).

18. A device according to claim 10, that further comprises a means for congestion control implementing TFRC (acronym for “

TCP-Friendly Rate Control”

) to provide said estimation of available rate.