Data communications system, data sender, data receiver, data communications method, and computer program

• US 20030126238A1
• Filed: 12/10/2002
• Published: 07/03/2003
• Est. Priority Date: 12/12/2001
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Itakura, Eisaburo, Kohno, Michinari
• Granted Patent: US 7,502,818 B2
• Time in Patent Office: Days
• US Class Current: 709/220
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• 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 1/18 Automatic repetition systems, e.g. Van Duuren systems
• 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 65/756 adapting media to device capabilities
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/161 Implementation details of TCP/IP or UDP/IP stack architecture; Specification of modified or new header fields
• CPC Class Codes: H04N 21/234327 by decomposing into layers, e.g. base layer and one or more enhancement layers
• CPC Class Codes: H04N 21/44209 Monitoring of downstream path of the transmission network originating from a server, e.g. bandwidth variations of a wireless network arrangements for maintenance or administration in data switching networks involving bandwidth and capacity management H04L41/0896
• CPC Class Codes: H04N 21/4621 Controlling the complexity of the content stream or additional data, e.g. lowering the resolution or bit-rate of the video stream for a mobile client with a small screen arrangements for using the results of monitoring on user's side in broadcast systems H04H60/65; flow control in packet networks H04L47/10
• CPC Class Codes: H04N 21/6437 Real-time Transport Protocol [RTP]

Abstract

A data communications system is provided to dynamically change the error processing between an ARQ function and an FEC function in accordance with the network status, thus enabling high-quality data playback. In packet transmission, error correction control is performed on the basis of the network status monitored by a network monitoring unit. The error control mode is switched between FEC-based error control and ARQ-based error control (retransmission request processing) in accordance with packet loss or error occurrence on the network, and packet transmission is performed. If the RTT is short, error correction based on ARQ is selected. If the RTT is long, error correction not based on ARQ but on FEC is selected. Such dynamic error correction control is achieved.

Claims

1. A data communications system for performing streaming data transmission, comprising:

a data sender; and

a data receiver,

wherein the data sender includes,

a packet sending processor for sending data packets containing data to be sent;

a network status monitoring unit for monitoring the network status;

a data-sender-side controller for controlling, on the basis of the network status monitored by the network status monitoring unit, an error control mode for the transmitted packets; and

a retransmission controller for extracting a data packet to be retransmitted in accordance with a retransmission request message packet received from the data receiver; and

wherein the data receiver includes,

a packet reception processor for receiving the data packets from the data sender;

an error correction controller for detecting an error or packet loss in the data packets received from the data sender and performing error-compliant processing; and

a retransmission request controller for determining, on the basis of the detection of the error or packet loss in the data packets received from the data sender, whether to send the retransmission request message packet serving as a data packet retransmission request to the data sender.

2. A data communications system according to claim 1, wherein the data-sender-side controller changes, on the basis of the network status monitored by the network status monitoring unit, the processing mode of forward error correction (FEC) serving as error control or the processing mode of automatic repeat request (ARQ) serving as data retransmission request processing.

3. A data communications system according to claim 1, wherein the network status monitoring unit analyzes the network status on the basis of a packet loss rate, transmission delay time, or the retransmission request from the data receiver and outputs an analysis result to the data-sender-side controller, and the data-sender-side controller controls the en-or control mode for the transmitted packets on the basis of the analysis result.

4. A data communications system according to claim 1, wherein the data receiver further comprises a data-receiver-side network status monitoring unit for monitoring the network status, and

the data-receiver-side network status monitoring unit analyzes the network status on the basis of a packet loss rate or transmission delay time and selects data to be processed on the basis of the analysis result.

5. A data communications system according to claim 1, wherein the data sender further includes,

a hierarchization unit for organizing encoded data to be sent into hierarchical layers;

and

a prioritization processor for specifying priority levels for the hierarchical layers generated by the hierarchization unit, and the data receiver further includes,

a data-receiver-side network status monitoring unit for monitoring the network status; and

a layer selection controller for selecting, in accordance with the hierarchy or priority, data to be processed on the basis of an analysis result by the data-receiver-side network status monitoring unit.

6. A data communications system according to claim 1, wherein the error correction controller of the data receiver performs error correction based on forward error correction (FEC) serving as error control or automatic repeat request (ARQ) serving as data retransmission request processing.

7. A data communications system according to claim 1, wherein the error correction controller of the data receiver controls sending of an ECHO packet to the data sender and reception of an ECHO-REPLY packet in response to the ECHO packet in order to compute a round trip time (RTT) between the data sender and the data receiver, and

on the basis of the RTT computed based on the ECHO packet and the ECHO-REPLY packet, it is determined whether reception of a retransmitted data packet in response to the retransmission request is feasible prior to the start of reading data stored in the retransmitted data packet.

8. A data communications system according to claim 1, wherein the data sender further comprises:

a hierarchization unit for organizing encoded data to be sent into hierarchical layers; and

a prioritization processor for specifying priority levels for the hierarchical layers generated by the hierarchization unit, and

the data-sender-side controller changes the hierarchization mode of the hierarchization unit or the processing mode of the prioritization processor in accordance with the network status.

9. A data communications system according to claim 1, wherein the data sender further comprises a hierarchization unit for organizing encoded data to be sent into hierarchical layers, and

the data-sender-side controller changes, on the basis of the network status monitored by the network status monitoring unit, the processing mode of forward error correction (FEC) serving as error control or the processing mode of automatic repeat request (ARQ) serving as data retransmission request processing in accordance with each of the hierarchical layers generated by the hierarchization unit.

10. A data communications system according to claim 1, wherein the data sender further comprises:

a hierarchization unit for organizing encoded data to be sent into hierarchical layers; and

a prioritization processor for specifying priority levels for the hierarchical layers generated by the hierarchization unit, and

the data-sender-side controller changes, on the basis of the network status monitored by the network status monitoring unit, the processing mode of forward error correction (FEC) serving as error control or the processing mode of automatic repeat request (ARQ) serving as data retransmission request processing in accordance with each of the priority levels specified by the prioritization processor.

11. A data sender for sending streaming data, comprising:

a packet sending processor for sending data packets containing data to be sent;

a network status monitoring unit for monitoring the network status;

a data-sender-side controller for controlling, on the basis of the network status monitored by the network status monitoring unit, an error control mode for the transmitted packets; and

a retransmission controller for extracting a data packet to be retransmitted in accordance with a retransmission request message packet received from a data receiver.

12. A data sender according to claim 11, wherein the data-sender-side controller changes, on the basis of the network status monitored by the network status monitoring unit, the processing mode of forward error correction (FEC) serving as error control or the processing mode of automatic repeat request (ARQ) serving as data retransmission request processing.

13. A data sender according to claim 11, wherein the network status monitoring unit analyzes the network status on the basis of a packet loss rate, transmission delay time, or the retransmission request from the data receiver and outputs an analysis result to the data-sender-side controller, and the data-sender-side controller controls the error control mode for the transmitted packets on the basis of the analysis result.

14. A data sender according to claim 11, further comprising:

a hierarchization unit for organizing encoded data to be sent into hierarchical layers; and

a prioritization processor for specifying priority levels for the hierarchical layers generated by the hierarchization unit,

wherein the data-sender-side controller changes the hierarchization mode of the hierarchization unit or the processing mode of the prioritization processor in accordance with the network status.

15. A data sender according to claim 11, further comprising a hierarchization unit for organizing encoded data to be sent into hierarchical layers,

wherein the data-sender-side controller changes, on the basis of the network status monitored by the network status monitoring unit, the processing mode of forward error correction (FEC) serving as error control or the processing mode of automatic repeat request (ARQ) serving as data retransmission request processing in accordance with each of the hierarchical layers generated by the hierarchization unit.

16. A data sender according to claim 11, further comprising:

a hierarchization unit for organizing encoded data to be sent into hierarchical layers; and

a prioritization processor for specifying priority levels for the hierarchical layers generated by the hierarchization unit,

wherein the data-sender-side controller changes, on the basis of the network status monitored by the network status monitoring unit, the processing mode of forward error correction (FEC) serving as error control or the processing mode of automatic repeat request (ARQ) serving as data retransmission request processing in accordance with each of the priority levels specified by the prioritization processor.

17. A data receiver for receiving streaming data, comprising:

a packet reception processor for receiving data packets from a data sender;

a network status monitoring unit for monitoring the network status;

an error correction controller for detecting an error or packet loss in the data packets received from the data sender and performing error-compliant processing;

a retransmission request controller for determining, on the basis of the detection of the error or packet loss in the data packets received from the data sender, whether to send a retransmission request message packet serving as a data packet retransmission request to the data sender; and

a layer selection controller for selecting the data to be processed on the basis of a monitoring result by the network status monitoring unit.

18. A data receiver according to claim 17, wherein the network status monitoring unit analyzes the network status on the basis of a packet loss rate or transmission delay time, and the layer selection controller selects data to be processed on the basis of the analysis result.

19. A data receiver according to claim 17, wherein the error correction controller of the data receiver performs error correction based on forward error correction (FEC) serving as error control or automatic repeat request (ARQ) serving as data retransmission request processing.

20. A data receiver according to claim 17, wherein the error correction controller of the data receiver controls sending of an ECHO packet to the data sender and reception of an ECHO-REPLY packet in response to the ECHO packet in order to compute a round trip time (RTT) between the data sender and the data receiver, and

on the basis of the RTT computed based on the ECHO packet and the ECHO-REPLY packet, it is determined whether reception of a retransmitted data packet in response to the retransmission request is feasible prior to the start of reading data stored in the retransmitted data packet.

21. A data communications method for performing streaming data transmission between a data sender and a data receiver, comprising:

a packet sending step of sending data packets containing data to be sent;

a network status monitoring step of monitoring the network status;

a data-sender-side controlling step of controlling, on the basis of the network status monitored in the network status monitoring step, an error control mode for the transmitted packets; and

a retransmission controlling step of extracting a data packet to be retransmitted in accordance with a retransmission request message packet received from the data receiver; and

a packet receiving step of receiving the data packets from the data sender;

an error correction controlling step of detecting an error or packet loss in the data packets received from the data sender and performing error-compliant processing; and

a retransmission request controlling step of determining, on the basis of the detection of the error or packet loss in the data packets received from the data sender, whether to send the retransmission request message packet serving as a data packet retransmission request to the data sender.

22. A data communications method according to claim 21, wherein the data-sender-side controlling step changes, on the basis of the network status monitored in the network status monitoring step, the processing mode of forward error correction (FEC) serving as error control or the processing mode of automatic repeat request (ARQ) serving as data retransmission request processing.

23. A data communications method according to claim 21, wherein the network status monitoring step analyzes the network status on the basis of a packet loss rate, transmission delay time, or the retransmission request from the data receiver, and the data-sender-side controlling step controls the error control mode for the transmitted packets on the basis of the analysis result.

24. A data communications method according to claim 21, further comprising the steps of performing network status monitoring for analyzing the network status on the basis of a packet loss rate or transmission delay time and selecting data to be processed on the basis of the monitoring result.

25. A data communications method according to claim 21, further comprising:

a hierarchization step of organizing encoded data to be sent into hierarchical layers; and

a prioritization processing step of specifying priority levels for the hierarchical layers generated in the hierarchization step, and

a layer selection controlling step of selecting, in accordance with the hierarchy or priority, data to be processed on the basis of the network status.

26. A data communications method according to claim 21, wherein the error correction controlling step performs error correction based on forward error correction (FEC) serving as error control or automatic repeat request (ARQ) serving as data retransmission request processing.

27. A data communications method according to claim 21, wherein the error correction controlling step includes:

a sending/reception step of sending an ECHO packet to the data sender and receiving an ECHO-REPLY packet in response to the ECHO packet in order to compute a round trip time (RTT) between the data sender and the data receiver; and

a determination step of determining, on the basis of the RTT computed based on the ECHO packet, whether reception of a retransmitted data packet in response to the retransmission request is feasible prior to the start of reading data stored in the retransmitted data packet.

28. A data communications method according to claim 21, further comprising:

a hierarchization step of organizing encoded data to be sent into hierarchical layers; and

a prioritization processing step of specifying priority levels for the hierarchical layers generated in the hierarchization step, and

wherein the data-sender-side controlling step changes the hierarchization mode or the prioritization mode in accordance with the network status.

29. A data communications method according to claim 21, further includes a hierarchization step of organizing encoded data to be sent into hierarchical layers, and

wherein the data-sender-side controlling step changes, on the basis of the network status, the processing mode of forward error correction (FEC) serving as error control or the processing mode of automatic repeat request (ARQ) serving as data retransmission request processing in accordance with each of the hierarchical layers.

30. A data communications method according to claim 21, further comprising:

a hierarchization step of organizing encoded data to be sent into hierarchical layers; and

a prioritization processing step of specifying priority levels for the hierarchical layers generated in the hierarchization step, and

wherein the data-sender-side controlling step changes, on the basis of the network status, the processing mode of forward error correction (FEC) serving as error control or the processing mode of automatic repeat request (ARQ) serving as data retransmission request processing in accordance with each of the priority levels.

31. A computer program for sending streaming data, comprising:

a packet sending step of sending data packets containing data to be sent;

a network status monitoring step of monitoring the network status;

a control step of controlling, on the basis of the network status monitored in the network status monitoring step, an error control mode for the transmitted packets; and

a retransmission controlling step of extracting a data packet to be retransmitted in accordance with a retransmission request message packet received from a data receiver.

32. A computer program for receiving streaming data, comprising:

a packet receiving step of receiving data packets from a data sender;

an error correction controlling step of detecting an error or packet loss in the data packets received from the data sender and performing error-compliant processing;

a retransmission request controlling step of determining, on the basis of the detection of the error or packet loss in the data packets received from the data sender, whether to send a retransmission request message packet serving as a data packet retransmission request to the data sender; and

a layer selection controlling step of selecting data to be processed on the basis of the monitoring result in the network status monitoring unit.