DATA COMMUNICATION APPARATUS AND METHOD

• US 20030037158A1
• Filed: 08/20/1998
• Published: 02/20/2003
• Est. Priority Date: 08/22/1997
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: SATO, HIROAKI, SHIMOYAMA, TOMOHIKO, YANO, KOICHI
• Granted Patent: US 6,701,372 B2
• Time in Patent Office: Days
• US Class Current: 709/232
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/34 ensuring sequence integrity, e.g. using sequence numbers
• CPC Class Codes: H04L 47/43 Assembling or disassembling of packets, e.g. segmentation and reassembly [SAR]
• CPC Class Codes: H04L 65/1083 In-session procedures
• 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 65/70 Media network packetisation
• CPC Class Codes: H04L 65/752 adapting media to network capabilities
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

This invention can make data communications at an optimal transfer rate on the basis of the unarrived data volume on a network between two end terminals.

For this purpose, a transmitting terminal (1-1) adds sequence number information to data generated by a data generator (1-11), and transmits the data to a receiving terminal (1-2) via a data transmitter (1-12). Since the receiving terminal (1-2) transmits data including the sequence number in the received data, the transmitting terminal determines that data (buffer capacity) corresponding to the difference between the current sequence number and the received sequence number remain on the network, and calculates that volume using a network buffer data volume calculator (1-14). The transmitting terminal determines the transmission rate on the basis of the calculation result, and controls the data transmitter (1-12) to transfer data at that transmission rate.

Claims

1. A data communication apparatus for transferring data to a terminal via a network, comprising:

detection means for detecting information related to a volume of data buffered on the network of the data making their way to the terminal;

means for obtaining a transfer rate on the basis of a detection result of said detection means; and

transfer means for transferring the data in accordance with the obtained transfer rate.

2. The apparatus according to claim 1, wherein said transfer means transfers the data by adding, to each unit of data to be transferred, identification information for specifying the unit.

3. The apparatus according to claim 2, wherein the terminal sends back information including the identification information in received data.

4. The apparatus according to claim 3, wherein said detection means detects the information related to the volume of data buffered on the network by detecting replay information including the identification information included in data sent back from the terminal.

5. The apparatus according to claim 2, wherein the identification information is sequence number information.

6. The apparatus according to claim 1, wherein said means for obtaining the transfer rate obtains a transfer rate with which a network buffer volume converges to a predetermined target buffer volume.

7. A data communication apparatus for receiving data sent from a data source apparatus on a network, comprising:

extraction means for extracting, from received data, identification information for specifying the received data; and

means for transmitting the extracted identification information as information for determining a transfer rate of the data source apparatus to the data source apparatus.

8. A data communication system built by a server for transmitting information, and a client for receiving data from said server via a network, said server comprising:

detection means for detecting information related to a volume of data buffered on said network of the data making their way to said client;

means for obtaining a transfer rate on the basis of a detection result of said detection means; and

transfer means for transferring the data in accordance with the obtained transfer rate, and said client comprising;

means for extracting identification information from data transmitted by said server and sending back data including the identification information.

9. A storage medium which stores a program serving as a data communication apparatus for transferring data to a terminal via a network, said storage medium storing program codes respectively serving as:

detection means for detecting information related to a volume of data buffered on the network of the data making their way to the terminal;

means for obtaining a transfer rate on the basis of a detection result of said detection means; and

transfer means for transferring the data in accordance with the obtained transfer rate.

10. A storage medium which stores a program serving as a data communication apparatus for receiving data sent from a data source apparatus on a network, said storage medium storing program codes respectively serving as:

extraction means for extracting, from received data, identification information for specifying the received data; and

means for transmitting the extracted identification information as information for determining a transfer rate of the data source apparatus to the data source apparatus.

11. A data communication apparatus for transferring data to a terminal via a network, comprising:

measurement means for measuring a data transfer time between itself and the terminal;

detection means for detecting information related to a volume of data buffered on the network of the data making their way to the terminal on the basis of the data transfer time measured by said measurement means;

means for obtaining a transfer rate on the basis of a detection result of said detection means; and

transfer means for transferring the data in accordance with the obtained transfer rate.

12. The apparatus according to claim 11, wherein said transfer means transfers the data by adding, to each unit of data to be transferred, transmission time information of the unit.

13. The apparatus according to claim 12, wherein the terminal sends back receiver report information including the transmission time information included in the received data, and processing time information required inside the terminal after the data is received.

14. The apparatus according to claim 13, wherein the receiver report information is sent back at a predetermined transmission time interval asynchronous with reception of data.

15. The apparatus according to claim 13, wherein said measurement means calculates a required round-trip time of a data communication on the basis of a reception time of the receiver report information from the terminal, and the transmission time information and the processing time information included in the receiver report information.

16. The apparatus according to claim 11, wherein said means for obtaining the transfer rate, includes:

calculation means for calculating the volume of data buffered on the network on the basis of the data transmission time measured by said measurement means; and

correction means for correcting the transfer rate on the basis of a difference between the calculated volume of data buffered on the network and a predetermined target value.

17. The apparatus according to claim 16, wherein said correction means corrects the transfer rate to decrease the difference from the target value.

18. The apparatus according to claim 17, wherein the target value is set in accordance with a transmission band of the network.

19. The apparatus according to claim 11, wherein the data transmitted to the terminal is video data sensed by predetermined image sensing means.

20. A reception apparatus serving as a terminal for receiving data from a data communication apparatus of claim 12, comprising:

receiving means for receiving data transferred from said data communication apparatus; and

means for sending back information including transmission time information included in the data received by said receiving means, and time information required from when the data is received until reply information is output to said data communication apparatus, as information for helping measurement by said measurement means.

21. The apparatus according to claim 11, wherein the network is a network complying with an RTP standardized by RFC1889.

22. A data communication method for transferring data to a terminal via a network, comprising:

the measurement step of measuring a data transfer time between a source apparatus and the terminal;

the detection step of detecting information related to a volume of data buffered on the network of the data making their way to the terminal on the basis of the data transfer time measured in the measurement step;

the step of obtaining a transfer rate on the basis of a detection result in the detection step; and

the transfer step of transferring the data in accordance with the obtained transfer rate.

23. A storage medium which stores a program code serving as a data communication apparatus for transferring data to a terminal via a network, said storage medium storing program codes respectively serving as:

measurement means for measuring a data transfer time between itself and the terminal;

detection means for detecting information related to a volume of data buffered on the network of the data making their way to the terminal on the basis of the data transfer time measured by said measurement means;

means for obtaining a transfer rate on the basis of a detection result of said detection means; and

transfer means for transferring the data in accordance with the obtained transfer rate.

24. A data communication system built by a transmitting apparatus for transmitting data via a network, and a receiving apparatus for receiving the data, said transmitting apparatus comprising:

measurement means for measuring a data transfer time between itself and said receiving apparatus;

detection means for detecting information related to a volume of data buffered on the network of the data making their way to said receiving apparatus on the basis of the data transfer time measured by said measurement means;

means for obtaining a transfer rate on the basis of a detection result of said detection means; and

transfer means for transferring the data in accordance with the obtained transfer rate, and said receiving apparatus comprising;

receiving means for receiving data from said transmitting apparatus; and

reply means for generating information for helping measurement of said measurement means based on the data received by said receiving means, and sending back the information to said transmitting apparatus.

25. The system according to claim 24, wherein said transfer means transfers the data by adding, to each unit of data to be transferred, transmission time information of the unit, and

said reply means generates information including the transmission time information included in the data received by said receiving means, and time information required for a reply, and sends back the information.

26. A video communication system in which a video transmitting apparatus transmits video data to a video receiving apparatus via a network,

said video transmitting apparatus comprising:

receiving means for receiving reception condition information from said video receiving apparatus;

generation means for generating a volume of data which is present on the network and has not reached said video receiving apparatus, on the basis of the received reception condition information; and

control means for controlling to output video data onto the network at a timing between adjacent frames of the video data on the basis of the generated volume of data on the networks.

27. The system according to claim 26, wherein the video data is moving image data captured by predetermined image sensing means.

28. The system according to claim 26, wherein upon outputting video data onto the network, said control means outputs packet data obtained by segmenting the video data to be output into a plurality of video data, and adding sequence information for specifying each of the segmented video data to the segmented video data.

29. The system according to claim 28, wherein said video receiving apparatus comprising means for transmitting sequence information and reception rate information of the latest received data as reception condition information to said video transmitting apparatus by a predetermined interval.

30. The system according to claim 29, wherein said control means comprises second calculation means for calculating, when intermediate packet data of one video frame are being transferred:

a transmission rate of remaining packets of the video frame;

a transmission start timing of the next frame; and

a transmission rate of the next frame.

31. The system according to claim 30, wherein said second calculation means calculates the transfer rate of the remaining packets of the video frame with a network buffer data volume matching a maximum target value.

32. The system according to claim 30, wherein said second calculation means calculates to maintain the volume of data not more than a predetermined value at an output timing of the next frame.

33. A video transmitting apparatus for transmitting video data to a video receiving apparatus via a network, comprising:

receiving means for receiving reception condition information from said video receiving apparatus;

generation means for generating a volume of data which is present on the network and has not reached said video receiving apparatus, on the basis of the received reception condition information; and

control means for controlling to output video data onto the network at a timing between adjacent frames of the video data on the basis of the generated volume of data.

34. A video receiving apparatus for receiving video data transmitted from a video transmitting apparatus of claim 33, comprising:

means for outputting reception condition information for latest received data to said video transmitting apparatus at a predetermined time interval.

35. A method of controlling a video transmitting apparatus for transmitting video data to a video receiving apparatus via a network, comprising:

the receiving step of receiving reception condition information from said video receiving apparatus;

the generation step of generating a volume of data which is present on the network and has not reached said video receiving apparatus, on the basis of the received reception condition information; and

the control step of controlling to output video data onto the network at a timing between adjacent frames of the video data on the basis of the generated volume of data.

36. A method of controlling a video receiving apparatus for receiving video data transmitted from a video transmitting apparatus of claim 35, comprising:

the step of outputting reception condition information for latest received data to said video transmitting apparatus at a predetermined time interval.

37. A storage medium which stores a program code serving as a video transmitting apparatus for transmitting video data to a video receiving apparatus via a network, when said program code is read and executed by a computer, said storage medium storing:

a program code of the receiving step of receiving reception condition information from said video receiving apparatus;

a program code of the generation step of generating a volume of data which is present on the network and has not reached said video receiving apparatus, on the basis of the received reception condition information; and

a program code of the control step of controlling to output video data onto the network at a timing between adjacent frames of the video data on the basis of the generated volume of data.

38. A storage medium which stores a program code serving as a video receiving apparatus for receiving video data transmitted from a video transmitting apparatus of claim 37, when said program code is read and executed by a computer, said storage medium storing:

a program code of the step of outputting reception condition information for latest received data to said video transmitting apparatus at a predetermined time interval.

39. A transmitting apparatus comprising:

transmitting means for transmitting data to a communication partner via a network;

determination means for determining the transmission condition of data on said network released to said network by said transmitting means; and

control means for controlling said transmitting means on the basis of the determination result of said determination means.

40. The apparatus according to claim 39, wherein said determination means determinates the transmission condition on the basis of reception rate information or time information included in a receiver report from said communication partner.

41. The apparatus according to claim 39, wherein said control means controls transmission rate of said transmitting means.

42. The apparatus according to claim 39, wherein said network is INTERNET.

43. The apparatus according to claim 40, wherein said receiver report is a report according to an RTP (Real Time Transport Protocol) standardized as RFC1889.

44. A transmitting apparatus which transmits data at a predetermined transmitting rate to a network and receives information related to data transmission condition on said network from said network,

wherein said predetermined transmitting rate is controlled on the basis of said information related to data transmission condition.

45. The apparatus according to claim 44, wherein said information related to data transmission condition is reception rate information or time information included in a receiver report from a communication partner via said network.

46. The apparatus according to claim 44, wherein said network is INTERNET.

47. A transmitting apparatus comprising:

adjusting means for adjusting transmitting rate based on reception rate information or time information included in a receiver report from a network.

48. The apparatus according to claim 47, wherein said receiver report is a report according to an RTP (Real Time Transport Protocol) standardized as RFC1889.

49. A transmitting apparatus comprising:

adjusting means for adjusting transmitting rate based on loss rate information, latest sequence number information and time information of last sender packet, which are included in a reception information from a receiver, and time period from the last sender packet.

50. The apparatus according to claim 49, wherein said receiver report is a report according to an RTP (Real Time Transport Protocol) standardized as RFC1889.