Determining strategy for multicast and/or unicast transmission to correct forward errors

• US 7,899,046 B2
• Filed: 07/07/2006
• Issued: 03/01/2011
• Est. Priority Date: 07/07/2006
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Scientific-Atlanta LLC (Cisco Systems, Inc.)
• Inventors: Ver Steeg, William C.
• Primary Examiner(s): Ton; Dang T
• Assistant Examiner(s): Kamara; Mohamed
• Application Number:
  US11/482,439
• Publication Number:
  US 20080008167A1
• Time in Patent Office: 1,698 Days
• Field of Search: 370/432, 370/390, 370/394, 371/5.5, 371/41, 714/774, 714/776, 714/782, 725/100, 725/131, 725/139
• US Class Current: 370/389
• 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 are disclosed herein for correcting errors. In one embodiment, among others, a method comprises receiving a plurality of error indications from a plurality of respective receivers. The receivers are configured to receive a data stream of packets transmitted within a multicast channel. Each error indication indicates which ones of a number of the packets were not received. The method further comprises analyzing the error indications to determine a first set of receivers to which forward error correction (FEC) code is transmitted and a second set of receivers to which unicast data is transmitted.

Claims

1. A method for correcting errors comprising:

receiving a plurality of error indications from a plurality of respective receivers, wherein the receivers receive a data stream of packets transmitted within a multicast channel, each error indication indicating which ones of a number of the packets were not received;

analyzing the plurality of error indications to determine if the error indications convey a pattern that can be represented by customized forward error correction (FEC) code;

creating the customized FEC code, when it is determined that a representable pattern has been conveyed; and

analyzing the error indications to determine a multicast/unicast strategy, wherein the multicast/unicast strategy comprises identifying a first set of receivers of the plurality of receivers to which the FEC code and an indication of the characteristics of the customized FEC code are transmitted via multicast and a second set of receivers of the plurality of receivers to which unicast data is transmitted.

2. The method of claim 1, further comprising:

sending data packets and a minimum amount of FEC code to the receivers before receiving the error indications.

3. The method of claim 1, further comprising:

transmitting a multicast of additional FEC to the first set of receivers.

4. The method of claim 1, further comprising:

transmitting at least one unicast packet to the second set of receivers.

5. The method of claim 4, wherein the at least one unicast includes at least one packet not received.

6. The method of claim 1, wherein analyzing the error indications comprises analyzing based on a number of packets not received by each receiver.

7. The method of claim 1, wherein receiving error indications includes receiving an indication of specific missed packets.

8. The method of claim 7, further comprising:

transmitting to the first set of receivers an amount of FEC code to correct a number of errors based on the specific missed packets.

9. The method of claim 7, further comprising:

transmitting to the second set of receivers data corresponding to the specific missed packets.

10. The method of claim 7, further comprising:

transmitting to the first set of receivers an amount of FEC code to correct up to a first predetermined number of errors;

transmitting to the second set of receivers data to restore up to a second predetermined number of errors; and

ignoring a set of receivers having more than the second predetermined number of errors.

11. The method of claim 1, further comprising:

transmitting an amount of FEC code to the first and second sets of receivers to correct a maximum number of missed packets, the maximum number based on the highest number of errors reported by one of the receivers.

12. A source device of a communication system, the source device comprising:

a buffer to store a plurality of data packets; and

a processor in communication with the buffer, wherein the processor;

receives error indications from a plurality of receiver devices,

analyzes the error indications to determine if the error indications convey a pattern that can be represented by customized forward error correction (FEC) code,

creates the customized FEC code if it is determined that a representable pattern has been conveyed, and

analyzes the error indications to determine a multicast/unicast strategy for transmitting error correction information to the plurality of receiver devices, wherein the customized FEC code and an indication of the characteristics of the customized FEC code are transmitted as multicast data to at least one first receiver of the plurality of receiver devices and unicast data is transmitted to at least one second receiver of the plurality of receiver devices.

13. The source device of claim 12, further comprising a driver in communication with the buffer and processor, wherein the driver transmits data from the buffer to the receiver devices.

14. The source device of claim 13, wherein the driver transmits the plurality of data packets and a first portion of the error correction information.

15. The source device of claim 14, wherein the driver transmits a second portion of the error correction information on a multicast channel corresponding to the multicast channel on which the first portion of error correction information is transmitted.

16. The source device of claim 14, wherein the driver transmits a second portion of the error correction information on a multicast channel that is different from the multicast channel on which the first portion of error correction information is transmitted.

17. The source device of claim 12, wherein the communication system is a multicast system.

18. The source device of claim 17, wherein the multicast system is an Internet protocol television (IPTV) system.

19. The source device of claim 12, wherein the processor transmits a multicast of error correction information to correct up to a first number of errors, and transmit one or more unicasts of specific data packets to correct up to a second number of errors, wherein the second number is higher than the first number, whereby a receiver device having more than the second number of errors does not receive enough error correction information or data to fully correct the errors.