Transmitting additional forward error correction (FEC) upon request

• US 20080028280A1
• Filed: 07/07/2006
• Published: 01/31/2008
• Est. Priority Date: 07/07/2006
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Scientific-Atlanta Incorporated (Cisco Systems, Inc.)
• Inventors: Ver Steeg, William C.
• Granted Patent: US 7,877,660 B2
• Time in Patent Office: Days
• US Class Current: 714/776
• CPC Class Codes: H04L 1/1819 with retransmission of additional or different redundancy
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint

Abstract

Systems and methods for providing forward error correction are disclosed in the present disclosure. In one embodiment, among others, a method comprises transmitting a stream of data packets to a receiver and transmitting a first amount of forward error correction (FEC) to the receiver. The first amount of FEC is designed to restore a first number of dropped data packets. The method also includes a receiving a message from the receiver that the first amount of FEC is not sufficient to restore a detected number of dropped data packets, and then transmitting additional FEC to restore the detected number of dropped data packets.

Claims

1. A method comprising:

transmitting a stream of data packets to a receiver;

transmitting a first amount of forward error correction (FEC) to the receiver, wherein the first amount of FEC is designed to restore a first number of dropped data packets;

receiving a message from the receiver that the amount of FEC is not sufficient to restore a detected number of dropped data packets; and

transmitting additional FEC to restore the detected number of dropped data packets.

2. The method of claim 1, wherein the first amount of FEC is no FEC.

3. The method of claim 1, wherein the first amount of FEC is sufficient to restore one dropped data packet.

4. The method of claim 1, further comprising:

calculating the additional FEC before transmitting the first amount of FEC to the receiver.

5. The method of claim 1, further comprising:

calculating the additional FEC after transmitting the first amount of FEC to the receiver.

6. The method of claim 1, wherein the message from the receiver indicates a specific number of dropped data packets, and wherein transmitting the additional FEC further comprises sending an amount of FEC that is sufficient, when combined with the first amount of FEC, to restore the specific number of dropped data packets.

7. The method of claim 1, wherein the message from the receiver indicates specific data packets that were dropped, and wherein transmitting the additional FEC further comprises sending an amount of FEC that is sufficient, when combined with the first amount of FEC, to restore a specific number of dropped data packets corresponding to the specific data packets that were dropped.

8. The method of claim 1, further comprising:

waiting, after transmitting the first amount of FEC, for a predetermined time period to receive the message from the receiver.

9. The method of claim 8, wherein the time period is related to the time for a signal to propagate to the receiver and back in addition to the time for the receiver to receive and process the data packets.

10. The method of claim 1, wherein the stream of data packets are transmitted on a first multicast channel and the first amount of FEC is transmitted on a second multicast channel.

11. A source device in a communication system, the source device comprising:

a driver configured to transmit data packets and forward error correction (FEC) to a receiver device downstream from the source device; and

a processor configured to receive a message from the receiver device, the message indicating the condition of the transmitted data packets;

wherein the processor is further configured to instruct the driver to transmit additional FEC to the receiver device as needed.

12. The source device of claim 11, wherein the source device is contained within a device selected from the group consisting of a multiplexer, digital subscriber line access multiplexer (DSLAM), decoder, router, digital contact manager (DCM), video acceleration module (VAM), and edge device.

13. The source device of claim 11, further comprising:

a buffer including a number of registers for storing the data and FEC.

14. The source device of claim 13, wherein the processor is further configured to access the data stored in the buffer to encode the FEC.

15. The source device of claim 11, wherein the driver is configured to transmit a first portion of the FEC with the data packets, wherein the first portion of FEC is sufficient to restore a number of dropped data packets.

16. The source of claim 11, wherein the processor is configured to analyze the message from the receiver device to determine an amount of additional FEC needed to restore data packets that the receiver device did not receive.

17. The source device of claim 16, wherein the processor is further configured to analyze messages from a plurality of receivers.

18. The source device of claim 17, wherein the processor is configured to determine the amount of additional FEC based on the analyzed messages.

19. The source device of claim 18, wherein the processor instructs the driver to transmit the additional FEC to the plurality of receivers.