Buffer for storing data and forward error correction (FEC)

• US 7,725,797 B2
• Filed: 07/07/2006
• Issued: 05/25/2010
• 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): Chase; Shelly A
• Application Number:
  US11/482,437
• Publication Number:
  US 20080022190A1
• Time in Patent Office: 1,418 Days
• Field of Search: 714/746, 714/776, 714/748, 714751-752, 370/390, 370/312
• US Class Current: 714/751
• CPC Class Codes: H04L 1/1819 with retransmission of additional or different redundancy
• CPC Class Codes: H04L 1/1848 Time-out mechanisms
• CPC Class Codes: H04L 1/188 Time-out mechanisms
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint

Abstract

Systems and methods are disclosed herein for transmitting data packets through a communication system. In one of several embodiments, a communication device in the communication system comprises a buffer configured to store a stream of data packets and forward error correction (FEC) code associated with the stream of data packets. The communication device also includes a processor configured to control the transmission of the stream of data packets and FEC code to a receiver device located downstream on the communication system. The processor is further configured to wait a predetermined period of time, after transmitting the stream of data packets and a portion of the FEC code, to determine whether or not the receiver device requests for additional FEC code.

Claims

1. A communication device in a communication system, the communication device comprising:

a buffer configured to store a stream of data packets and forward error correction (FEC) code associated with the stream of data packets; and

a processor configured to control the transmission of the stream of data packets and FEC code to a receiver device located downstream on the communication system;

wherein the processor is further configured to wait a predetermined period of time, after transmitting the stream of data packets and a portion of the FEC code, to determine whether or not the receiver device requests for additional FEC code wherein when the processor does not receive a request from the receiver device after the predetermined period of time, the processor determines that the receiver device does not require additional FEC code.

2. The communication device of claim 1, wherein the predetermined period of time is related to a round-trip time for a signal to propagate between the communication device and the receiver device.

3. The communication device of claim 2, wherein the predetermined period of time is further related to an amount of time for the receiver device to receive the entire stream of data packets and determine whether or not there is an error therein.

4. The communication device of claim 1, wherein, upon receiving a request for additional FEC code, the processor transmits a certain amount of additional FEC code to the receiver device.

5. The communication device of claim 4, wherein the processor is further configured to determine the certain amount of additional FEC code based on the request from the receiver device.

6. The communication device of claim 5, wherein the processor analyzes the request to determine the certain amount of additional FEC code for restoring a certain number of errors in the stream of data packets.

7. The communication device of claim 5, wherein the processor analyzes the request to determine the re-transmission of certain data packets in a unicast.

8. A receiver device of a communication system, the receiver device comprising:

a buffer for receiving and storing a stream of data packets and forward error correction (FEC); and

a processor in communication with the buffer, the processor configured to access the data packets and FEC from the buffer and determine whether or not data packets have been dropped or received with errors;

wherein, when it is determined that data packets have been dropped or received with errors, the processor is configured to determine whether or not the FEC is sufficient to restore the dropped or faulty data packets; and

wherein, when the FEC is not sufficient to restore the dropped data packets, the processor is configured to send a request for additional FEC, the processor being further configured to wait a predetermined amount of time for a first transmitting device of the communication system to receive the request and transmit additional FEC to the buffer.

9. The receiver device of claim 8, wherein the predetermined amount of time is related to a round-trip time for a signal to propagate between the first transmitting device and the receiver device.

10. The receiver device of claim 9, wherein the predetermined amount of time is further related to an amount of time for the buffer to store the stream of data packets and for the processor to determine whether or not the FEC is sufficient.

11. The receiver device of claim 8, wherein data packets are received on a first multicast and the FEC is received on a second multicast.

12. The receiver device of claim 8, wherein the buffer receives data packets from a second transmitting device.

13. The receiver device of claim 12, wherein the first transmitting device is associated with one of:

a multicast group unrelated to the second transmitting device;

or a file transfer protocol (FTP) exchange.

14. The receiver device of claim 8, wherein, if the buffer does not receive additional FEC after the processor waits for the predetermined amount of time, the processor attempts to use any received FEC to restore the dropped data packets as much as possible.

15. A method comprising:

temporarily storing data packets and forward error correction (FEC) associated with the data packets;

waiting for a period of time to determine whether a number of the data packets or a portion of the FEC are to be transmitted;

determining whether or not detected errors in the data packets are below a first determined threshold; and

allowing the portion of the FEC to be transmitted when the detected errors are below the first determined threshold.

16. The method of claim 15, further comprising:

determining whether or not detected errors in the data packets are below a second determined threshold, the second determined threshold being higher than the first determined threshold; and

allowing one or more data packets to be transmitted when the detected errors are below the second determined threshold.

17. The method of claim 16, wherein the first and second determined thresholds are predetermined.

18. The method of claim 15, wherein, after waiting for the period of time and determining that a number of the data packets or a portion of the FEC are not to be transmitted, allowing the data packets to be transmitted down the communication system with uncorrected errors.