Method and system for adapting forward error correction in multicast over wireless networks

1. A method, said method comprising:

receiving channel condition feedback from a first device over a wireless channel;

determining, based on said received feedback, whether said first device is served;

determining responsive to a first determining act and responsive to said received channel condition feedback if a currently used forward error correction coding rate is sufficient for said first device to recover lost data;

adjusting said currently used forward error correction coding rate responsive to said determining act;

generating additional forward error correction packets for source data using said adjusted forward error correction coding rate; and

transmitting to a second device said additional forward error correcting packets in a plurality of multicast groups with different priorities.

2. The method according to claim 1 , further comprising:

adjusting said forward error correction coding rate responsive to receiving feedback from multiple devices in a class of devices if a time interval has expired;

determining a physical layer mode of operation and a packet size for said source data based on said feedback from multiple devices in said class of devices;

packetizing said source data responsive to said determined packet size; and

packetizing forward error correction data responsive to said determined packet size;

transmitting said packetized source data in a first multicast group and said forward error correction packets in said plurality of multicast groups, said plurality of multicast groups not including said first multicast group and each of said plurality of multicast groups containing different forward error correction packets.

3. The method according to claim 2 , wherein said transmitting act is performed responsive to said physical layer mode of operation.

4. The method according to claim 2 , wherein said second determining act determines if a packet loss rate is one of less than and equal to a threshold.

5. The method according to claim 2 , wherein said second adjusting act is performed based on the forward error correction coding rate required for said multiple receivers in said class to correct their packet loss.

6. The method according to claim 1 , wherein said first adjusting act is performed based on the forward error correction coding rate required for said receiver to correct its packet loss.

7. The method according to claim 1 , wherein said multicast groups are transmitted based on available bandwidth.

8. The method according to claim 1 , wherein said multicast groups are staggercast.

9. The method according to claim 1 , wherein said source data packets and said forward error correction packets are interleaved.

10. The method according to claim 1 , wherein said method is performed in a server.

11. An apparatus, comprising:

means for receiving channel condition feedback from a first device over a wireless channel;

means for determining, based on said received feedback, whether said first device is served;

means for determining responsive to a first determining means and responsive to said channel condition feedback if a currently used forward error correction coding rate is sufficient for said device to recover lost data;

means for adjusting said currently used forward error correction coding rate responsive to said determining act;

means for generating additional forward error correction packets for source data using said adjusted forward error correction coding rate; and

means for transmitting to a second device said additional forward error correcting packets in a plurality of multicast groups with different priorities.

12. The apparatus according to claim 11 , further comprising:

means for adjusting said forward error correction coding rate responsive to receiving feedback from multiple devices in a class of devices if a time interval has expired;

means for determining a physical layer mode of operation and a packet size for said source data based on said feedback from multiple devices in said class of devices;

means for packetizing said source data responsive to said determined packet size; and

means for packetizing forward error correction data responsive to said determined packet size;

means for transmitting said packetized source data in a first multicast group and said forward error correction packets in said plurality of multicast groups, said plurality of multicast groups not including said first multicast group, and each of said plurality of multicast groups containing different forward error correction packets.

13. The apparatus according to claim 12 , wherein said means for transmitting is performed responsive to said physical layer mode of operation.

14. The apparatus according to claim 12 , wherein said second determining means determines if a packet loss rate is one of less than and equal to a threshold.

15. The apparatus according to claim 12 , wherein said second adjusting means is based on the forward error correction coding rate required for said multiple receivers in said class to correct their packet loss.

16. The apparatus according to claim 11 , wherein said first adjusting means is based on the forward error correction coding rate required for said receiver to correct its packet loss.

17. The apparatus according to claim 11 , wherein said multicast groups are transmitted based on available bandwidth.

18. The apparatus according to claim 11 , wherein said multicast groups are staggercast.

19. The apparatus according to claim 11 , wherein said source data packets and said forward error correction packets are interleaved.

20. The apparatus according to claim 11 , wherein said apparatus is a server.