IMPORTANCE-BASED FED-AWARE ERROR-REPAIR SCHEDULING

• US 20100005360A1
• Filed: 07/07/2008
• Published: 01/07/2010
• Est. Priority Date: 07/07/2008
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Oran, David R., Begen, Ali C.
• Granted Patent: US 9,312,989 B2
• Time in Patent Office: Days
• US Class Current: 714/751
• CPC Class Codes: G06F 11/1443 Transmit or communication errors
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/16 in which the return channel carries supervisory signals, e.g. repetition request signals
• CPC Class Codes: H04L 1/1614 using bitmaps
• CPC Class Codes: H04L 1/1621 Group acknowledgement, i.e. the acknowledgement message defining a range of identifiers, e.g. of sequence numbers
• CPC Class Codes: H04L 1/1628 List acknowledgements, i.e. the acknowledgement message consisting of a list of identifiers, e.g. of sequence numbers H04L1/1614 takes precedence
• CPC Class Codes: H04L 1/1819 with retransmission of additional or different redundancy
• CPC Class Codes: H04L 1/1845 Combining techniques, e.g. code combining
• CPC Class Codes: H04L 1/1867 Arrangements specially adapted for the transmitter end
• CPC Class Codes: H04L 2001/0092 Error control systems characterised by the topology of the transmission link
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint

Abstract

Particular embodiments generally relate to providing retransmission that is forward error correction (FEC) aware. In one embodiment, information is received that defines a plurality of missing packets for a media stream for a receiver. The plurality of missing packets may define FEC packets and source packets that are missing at the receiver. A retransmission server determines one or more retransmission packets for retransmission based on the FEC packets and source packets received at the receiver. In taking into account the FEC packets and source packets received at the receiver, retransmission of all missing source packets may not be necessary. The one or more retransmission packets are then sent to the receiver and the receiver can use the one or more retransmission packets to recover the plurality of missing source packets. The retransmission server may take into account the FEC and source packets received at multiple receivers and perform error repair such that a maximum total number of source packets can be repaired at all receivers.

Claims

1. A method comprising:

receiving a loss report, the loss report usable to determine a plurality of missing packets at a first receiver, the missing packets including one or more forward error correction packets and/or one or more source packets;

determining one or more retransmission packets for retransmission based on a forward error correction (FEC) scheme and the plurality of missing packets at the first receiver, wherein the one or more retransmission packets are determined to allow the first receiver to recover at least one of the missing source packets in the one or more source packets using the FEC scheme after receiving the one or more retransmission packets; and

sending the one or more retransmission packets to the first receiver, the one or more retransmission packets allowing the first receiver to recover at least one of the missing source packets in the one or more source packets that it is missing using the forward error correction scheme after receiving the one or more retransmission packets.

2. The method of claim 1, wherein determining the one or more retransmission packets comprises determining which of FEC or source packets need to be retransmitted to allow the first receiver to recover all the missing source packets based on the FEC scheme used, wherein the FEC or source packets determined for retransmission are a minimum number of retransmission packets that can be sent to allow all of the missing source packets to be recovered using the FEC scheme.

3. The method of claim 1, further comprising:

receiving a one or more additional loss reports that are used to determine one or more additional plurality of missing packets at one or more additional receivers, the one or more additional loss reports usable to determine one or more forward error correction (FEC) packets and/or one or more source packets missing at the one or more additional receivers;

determining one or more retransmission packets for retransmission that can be sent to the first receiver and the one or more additional receivers based on a forward error correction (FEC) scheme, source packets, and FEC packets received at the first receiver and the one or more additional receivers to allow the first receiver to recover at least a portion of the missing one or more source packets at the first receiver and the one or more additional receivers to recover at least a portion of the missing one or more source packets at the one or more additional receivers; and

sending the one or more retransmission packets to the first receiver and the one or more additional receivers.

4. The method of claim 3, wherein the one or more retransmission packets are sent via multicast to the first receiver and the one or more additional receivers.

5. The method of claim 1, wherein determining the one or more retransmission packets comprises:

determining a relative importance for the one or more retransmission packets; and

sending a retransmission packet to the first receiver considered to have the highest relative importance before the other retransmission packets.

6. The method of claim 5, wherein determining the relative importance comprises:

determining a missing packet that carries a more important payload compared to other missing packets; and

retransmitting the most important missing packet before other missing packets.

7. The method of claim 1, wherein determining one or more retransmission packets comprises:

determining an FEC packet that can be used to recover a missing source packet; and

sending the FEC packet instead of the missing source packet.

8. The method of claim 1, wherein one or more retransmission packets sent are less than a number of the plurality of missing packets and are used to recover all of the missing one or more source packets.

11. The method of claim 8, wherein sending the loss report comprises sending the loss report upon a determination that FEC will not recover the missing one or more source packets, wherein the loss report is sent before a last packet in an FEC block is received.

9. A method comprising:

determining, at a first receiver, a plurality of missing packets from a media stream;

generating a loss report defining the plurality of missing packets, the loss report usable to determine one or more forward error correction (FEC) packets and/or one or more source packets missing at the first receiver;

sending the loss report to a retransmission server;

receiving one or more retransmission packets for retransmission based on a forward error correction (FEC) scheme and the plurality of missing packets at the first receiver; and

recovering one or more source packets that the first receiver is missing after receiving the one or more retransmission packets using the FEC scheme.

10. The method of claim 9, wherein recovering comprises;

sending the one or more retransmission packets to an FEC decoder; and

using the FEC decoder to recover the one or more source packets that the first receiver is missing using the FEC scheme.

12. An apparatus comprising:

one or more processors; and

logic encoded in one or more tangible media for execution by the one or more processors and when executed operable to;

receive a loss report, the loss report usable to determine a plurality of missing packets at a first receiver, the missing packets including one or more forward error correction packets and/or one or more source packets;

determine one or more retransmission packets for retransmission based on a forward error correction (FEC) scheme and the plurality of missing packets at the first receiver, wherein the one or more retransmission packets are determined to allow the first receiver to recover at least one of the missing source packets in the one or more source packets using the FEC scheme after receiving the one or more retransmission packets; and

send the one or more retransmission packets to the first receiver, the one or more retransmission packets allowing the first receiver to recover at least one of the missing source packets in the one or more source packets that it is missing using the forward error correction scheme after receiving the one or more retransmission packets.

13. The apparatus of claim 12, wherein logic operable to determine the one or more retransmission packets comprises logic operable to determine which of FEC or source packets need to be retransmitted to allow the first receiver to recover all the missing source packets based on the FEC scheme used, wherein the FEC or source packets determined for retransmission are a minimum number of retransmission packets that can be sent to allow all of the missing source packets to be recovered using the FEC scheme.

14. The apparatus of claim 12, wherein the logic when executed is further operable to:

receive a one or more additional loss reports that are used to determine one or more additional plurality of missing packets at one or more additional receivers, the one or more additional loss reports usable to determine one or more forward error correction (FEC) packets and/or one or more source packets missing at the one or more additional receivers;

determine one or more retransmission packets for retransmission that can be sent to the first receiver and the one or more additional receivers based on a forward error correction (FEC) scheme, source packets, and FEC packets received at the first receiver and the one or more additional receivers to allow the first receiver to recover at least a portion of the missing one or more source packets at the first receiver and the one or more additional receivers to recover at least a portion of the missing one or more source packets at the one or more additional receivers; and

send the one or more retransmission packets to the first receiver and the one or more additional receivers.

15. The apparatus of claim 14, wherein the one or more retransmission packets are sent via multicast to the first receiver and the one or more additional receivers.

16. The apparatus of claim 12, wherein logic operable to determine the one or more retransmission packets comprises logic operable to:

determine a relative importance for the one or more retransmission packets; and

send a retransmission packet to the first receiver considered to have the highest relative importance before the other retransmission packets.

17. The apparatus of claim 16, wherein logic operable to determine the relative importance comprises logic operable to:

determining a missing packet that carries a more important payload compared to other missing packets; and

retransmitting the most important missing packet before other missing packets.

18. The apparatus of claim 12, wherein logic operable to determine one or more retransmission packets comprises logic operable to:

determine an FEC packet that can be used to recover a missing source packet; and

send the FEC packet instead of the missing source packet.

19. An apparatus comprising:

one or more processors; and

logic encoded in one or more tangible media for execution by the one or more processors and when executed operable to;

determine, at a first receiver, a plurality of missing packets from a media stream;

generate a loss report defining the plurality of missing packets, the loss report usable to determine one or more forward error correction (FEC) packets and/or one or more source packets missing at the first receiver;

send the loss report to a retransmission server;

receive one or more retransmission packets for retransmission based on a forward error correction (FEC) scheme and the plurality of missing packets at the first receiver; and

recover one or more source packets that the first receiver is missing after receiving the one or more retransmission packets using the FEC scheme.

20. A method comprising:

receiving a first loss report that defines a plurality of missing packets at a first receiver, the first loss report usable to determine one or more forward error correction (FEC) packets and/or one or more source packets missing at the first receiver;

receiving a second loss report that defines a plurality of missing packets at a second receiver, the second loss report usable to determine one or more forward error correction (FEC) packets and/or one or more source packets missing at the second receiver;

determining one or more retransmission packets for retransmission based on a forward error correction (FEC) scheme and the plurality of missing packets defined in the first loss report and the second loss report, wherein the one or more retransmission packets are sent to both the first receiver and the second receiver; and

sending the one or more retransmission packets to the first receiver and the second receiver, the one or more retransmission packets allowing the first receiver to recover at least one of the missing source packets that the first receiver is missing after receiving the one or more retransmission packets and allowing the second receiver to recover at least one of the missing source packets that the second receiver is missing after receiving one or more retransmission packets.