Method and apparatus for multicasting with feedback information

1. A method for multicasting a packet, comprising:

providing a buffer at a base station for each of two user equipments (UEs) in communication with the base station, each buffer configured to store packets to be sent to the corresponding UE;

determining whether there is a new packet at the base station to be transmitted to a UE, wherein a new packet is a previously unsent packet;

determining whether both UE buffers are non-empty;

flushing a non-empty buffer on a condition that there is no new packet and on a condition that one of the buffers is non-empty;

selecting a packet to transmit on a condition that there is a new packet or on a condition that both buffers are non-empty, wherein a combined packet is selected on a condition that there is no packet that has been previously transmitted but not acknowledged by both UEs and on a condition that both buffers are non-empty, wherein a combined packet is an exclusive OR combination of a first packet in each buffer; and

updating the buffers based on feedback received from the UEs, wherein the updating includes removing a packet from a buffer on a condition that the UE acknowledges receipt of the packet.

2. The method according to claim 1 , wherein the flushing includes:

determining whether the buffer is empty;

transmitting a packet from the buffer on a condition that the buffer is non-empty;

updating the buffer based on feedback received from the UE, wherein the updating includes removing a packet from a buffer on a condition that the UE acknowledges receipt of the packet; and

repeating the flushing until the buffer is empty.

3. The method according to claim 1 , wherein the selecting includes:

transmitting a packet that has been previously transmitted but not acknowledged by both UEs.

4. The method according to claim 1 , wherein the selecting includes:

transmitting a new packet on a condition that there is no packet that has been previously transmitted but not acknowledged by both UEs and on a condition that one of the buffers is empty.

5. The method according to claim 1 , wherein the selecting includes:

examining a first packet in a non-empty buffer;

determining whether the first packet is a predetermined number of packets ahead of a most recently transmitted packet; and

transmitting the first packet on a condition that the first packet is the predetermined number of packets ahead of the most recently transmitted packet.

6. The method according to claim 5 , wherein the predetermined number of packets ahead of the most recently transmitted packet corresponds to a maximum delay value.

7. The method according to claim 1 , wherein the selecting includes transmitting a first packet in the buffer on a condition that the buffer has reached a predetermined buffer capacity.

8. A method for providing feedback in a multicast communication system, comprising:

receiving a packet from a base station;

determining whether the received packet is a combined packet;

recovering individual packets from the combined packet, wherein the recovering includes performing an exclusive OR operation on the combined packet and a previously received packet, whereby a previously unsuccessfully received packet is recovered; and

providing feedback to the base station for any individual packet in the combined packet that was not previously successfully received.

9. A base station configured to multicast a packet, comprising:

two buffers, one buffer for each of two user equipments (UEs) in communication with the base station;

a processor configured to:

determine whether there is a new packet to be transmitted to a UE, wherein a new packet is a previously unsent packet; and

determine whether both buffers are non-empty;

a buffer flushing device configured to flush a non-empty buffer on a condition that there is no new packet and on a condition that one of the buffers is non-empty;

a packet selector configured to

select a packet to transmit on a condition that there is a new packet or on a condition that both buffers are non-empty;

select a combined packet on a condition that there is no packet that has been previously transmitted but not acknowledged by both UEs and on a condition that both buffers are non-empty, wherein a combined packet is an exclusive OR combination of a first packet in each buffer;

a buffer updating device configured to:

update the buffers based on feedback received from the UEs; and

remove a packet from a buffer on a condition that the packet has been acknowledged by the corresponding UE; and

a transceiver configured to transmit packets and to receive feedback information.

10. The base station according to claim 9 , wherein said buffer flushing device is configured to:

determine whether the buffer is empty;

select a packet from the buffer for transmission on a condition that the buffer is not empty; and

repeat flushing the buffer until the buffer is empty.

11. The base station according to claim 9 , wherein said packet selector is configured to select a packet that has been previously transmitted but not acknowledged by both UEs.

12. The base station according to claim 9 , wherein said packet selector is configured to select a new packet on a condition that there is no packet that has been previously transmitted but not acknowledged by both UEs and on a condition that one of said buffers is empty.

13. The base station according to claim 9 , wherein said packet selector is configured to:

examine a first packet in a non-empty buffer;

determine whether the first packet is a predetermined number of packets ahead of a most recently transmitted packet; and

select the first packet on a condition that the first packet is the predetermined number of packets ahead of the most recently transmitted packet.

14. The base station according to claim 13 , wherein the predetermined number of packets ahead of the most recently transmitted packet corresponds to a maximum delay value.

15. The base station according to claim 9 , wherein said packet selector is configured to select a first packet in the buffer on a condition that the buffer has reached a predetermined buffer capacity.