Point to multipoint reliable protocol for synchronous streaming data in a lossy IP network

• US 20080228936A1
• Filed: 03/12/2007
• Published: 09/18/2008
• Est. Priority Date: 03/12/2007
• Status: Active Grant

• Current Assignee: Nautel Limited
• Original Assignee: Nautel Limited
• Inventors: Martin, Scott, Schmid, Philipp
• Granted Patent: US 7,865,610 B2
• Time in Patent Office: Days
• US Class Current: 709/232
• CPC Class Codes: H04H 20/82 using signals not modulated onto a carrier
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/1838 for semi-reliable protocols, e.g. for less sensitive applications such as streaming video buffer level management for video bitstream receiver H04N21/44004
• CPC Class Codes: H04L 1/1854 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 1/1877 for semi-reliable protocols, e.g. for less sensitive applications like streaming video buffer level management for video bitstream control arrangements H04N21/44004
• CPC Class Codes: H04L 12/1863 comprising mechanisms for improved reliability, e.g. status reports arrangements for detecting or preventing errors by carrying supervisory signal the return channel H04L1/16
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/38 by adapting coding or compression rate
• CPC Class Codes: H04L 65/611 for multicast or broadcast systems for broadcast or conference H04L12/18; arrangements for broadcast or distribution combined with broadcast H04H20/00; arrangements for broadcast applications with a direct linkage to broadcast information or to broadcast space-time H04H60/00; selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS], H04W4/06
• 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 69/324 in the data link layer [OSI layer 2], e.g. HDLC
• CPC Class Codes: H04W 28/02 Traffic management, e.g. flow control or congestion control
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365
• CPC Class Codes: H04W 28/22 Negotiating communication rate
• CPC Class Codes: H04W 8/04 Registration at HLR or HSS [Home Subscriber Server]

Abstract

A method and apparatus for improving the reliability in the synchronous streaming of data from a sender to multiple receivers, especially in networks having a limited bandwidth. The sender is configured to change the format of the data to be sent by segmenting the data into packets having maximum size, and identifying each packet with a message number. The transmit rate of the sender is adjusted according to the throughput bandwidth of the link so as to avoid congesting the link. Each receiver is configured to re-assemble the packets based upon the message number allocated to each packet, and re-create the data in the original format for being read by standard HDJ Radio Exciters. The Receivers may also be configured to keep track of the packet numbers and request re-transmission of lost packets, using the ARQ (Automatic Retransmission Request) scheme.

Claims

1. A data transmission system for improving the streaming of data between a sender and at least one receiver over a connection link, wherein

the sender is configured to change the format of the data to be sent by segmenting and encapsulating the data into packets of a maximum size, and identifying each packet with a message number, wherein a transmit rate of the sender is adjusted according to the throughput bandwidth of the link so as to avoid congesting the link;

and

the receiver is configured to re-assemble the packets based upon the message number allocated to each packet, and re-create the data in the original format for being read by standard applications.

2. A data transmission system according to claim 1, wherein

the sender is an exporter at a studio;

the receiver is an exciter engine at a transmitter station; and

the data that is segmented is a standard E2X packet.

3. A data transmission system according to claim 2, wherein the system includes an Internet Protocol (IP) Layer, and the transmission of data is effected over a lower level protocol.

4. A data transmission system according to claim 3, wherein, by executing statements and instructions recorded on a first storage memory, the exporter performs operations including:

inputting standard E2X packets and segmenting these into smaller segments, and assigning a sequence number for each segment;

placing the segments in a main queue for mixing with segments previously sent and recorded in a buffer for possible re-transmission, and which are selected and stored in a re-transmit queue upon request for re-transmission and identification of the requested segments from the exgine;

scheduling the segments for transmission between the main queue and the re-transmit queue, encapsulating the segments in a new packet including a control header and placing them into a transmit queue for transmission to the exgine, taking into consideration the link throughput bandwidth so as to provide a constant streaming of data in a manner that avoids congesting the link.

5. A data transmission system according to claim 4, wherein a random delay with uniform PDF is inserted into the encapsulated packet in order to allow multiple E2X streams to co-exist on the same link, whereby clock packets of another stream appear like a white noise on a designated exgine PLL.

6. A data transmission system according to claim 4, wherein each segment is identified by the message number that indicates to which packet the segment belongs, and the sequence number that indicates the rank of the segment inside the packet.

7. A data transmission system according to claim 4, wherein the execution of the statements and instructions recorded in the first storage memory causes the exporter to maintain a per-segment transmit time stamp in order to avoid re-transmitting the same segment unless a predefined time frame elapses after the previous re-transmission.

8. A data transmission system according to claim 4, wherein the encapsulated packet includes an IP precedence field in the header thereof, for prioritizing the transmission of segments which are more timing critical.

9. A data transmission system according to claim 1, wherein the sender sends a configuration packet periodically to permit said at least one receiver to be configured after a power on, reset or the like.

10. A data transmission system according to claim 9, wherein the period of sending the configuration packet is the frame time of the pre-existing protocol.

11. A data transmission system according to claim 4, wherein, by executing statements and instructions recorded on a second storage memory, the exgine may perform operations including:

receiving the encapsulated packets sent from the exporter;

de-capsulating the encapsulated packets and re-assembling the segments in order of segmentation at the exporter based upon the sequence number and message number of each segment; and

sending the re-assembled segments to the exgine as standard E2X packets;

whereby the data transmission system improves the reliability of transmission by providing a relatively constant bit rate data stream, and maintains backward compatibility with the pre-existing E2X protocol.

12. A data transmission system according to claim 11, wherein the operations performed by the exgine further include the step of requesting re-transmission of lost segments based on gaps in the sequence numbers of the segments received.

13. A data transmission system according to claim 12, wherein the exporter is configured to use the maximum available bandwidth for sending the requested packets in order to avoid congestion caused by a large number of re-transmission requests.

22. A data transmission system according to claim 4, wherein the first storage memory is included in the exporter, or may be provided as an independent network component.

23. A data transmission system according to claim 11, wherein the second storage memory is included in the exciter, or may be provided as an independent network component.

24. A data transmission system according to claim 11, wherein the statements and instructions of the second memory may be used as a multimedia component which allows the HDJ content to be delivered to an end-user over an end-user network.

25. A data transmission system according to claim 2, wherein the system includes an Internet Protocol (IP) Layer, a UDP Layer, and the transmission of data is effected over the UDP/IP mode.

26. A data transmission system according to claim 12, the re-transmission request is only made after a certain time had elapsed after the previous re-transmission request.

14. A method for streaming data between an exporter and at least one exgine using the E2X protocol over a connection link, the method includes the steps of:

inputting standard E2X packets and segmenting these into smaller segments;

assigning a sequence number to each segment representing the rank of the segment in the packet, and a message number representing the packet to which the segment belongs, and placing the segments in a main queue;

checking a re-transmit queue for the existence of other segments requested for re-transmission by the exgine, and which can be retrieved from a buffer which records the previously sent segments;

scheduling the segments for transmission between the segments found in the main queue and those found in the re-transmit queue and encapsulating these segments into packets having a maximum size;

transmitting the encapsulated packets and adjusting the transmit rate based upon the link throughput bandwidth so as to avoids congesting the link;

receiving the encapsulated packets at an exgine and re-assembling the segments in order of segmentation at the exporter based upon the sequence number and message number of each segment, and

re-creating the standard E2X packets which can be read by a standard exgine;

whereby the reliability of transmission can be improved while maintaining backward compatibility with the pre-existing E2X protocol.

15. A method for streaming data according to claim 14, further including the step of requesting re-transmission of lost segments based on gaps in the sequence numbers of the segments received.

16. A method for streaming data according to claim 14, wherein a random delay with uniform PDF is inserted into the encapsulated packet in order to allow multiple E2X streams to co-exist on the same link, whereby clock packets of another stream appear like a white noise on a designated exgine PLL.

17. A method for streaming data according to claim 15, further including a step of maintaining a per-segment transmit time stamp in order to avoid re-transmitting the same segment unless a predefined time frame elapses after the previous re-transmission.

18. A method for streaming data according to claim 15, further including the step of including an IP precedence field in the header of the encapsulated packet for prioritizing the transmission of segments which are more timing critical.

19. A method for streaming data according to claim 14, further including the step of periodically sending a configuration packet to permit exgines to be configured after a power on, reset or the like.

20. A method for streaming data according to claim 19, wherein the period of sending the configuration packet is the frame time of the pre-existing protocol.

21. A method for streaming data according to claim 15, wherein it is possible to use the maximum available bandwidth for sending the requested packets in order to avoid congestion caused by a large number of re-transmission requests.

27. A method for streaming data according to claim 14, wherein the transmission of data is effected over the UDP/IP protocol.

28. A method for streaming data according to claim 15, wherein the re-transmission request is only made after a certain time had elapsed after the previous re-transmission request.