초록 ▼

A method supports scalable and reliable multicast in a wireless network with a large bandwidth-delay product. In this method, acknowledgement packets from different receivers experiencing the same number of data packets lost are assigned the same time slots. This method can be combined with other lo

A method supports scalable and reliable multicast in a wireless network with a large bandwidth-delay product. In this method, acknowledgement packets from different receivers experiencing the same number of data packets lost are assigned the same time slots. This method can be combined with other loss recovery techniques, such as forward error correction (FEC) recovery, proactive protection, feedback suppression and collision detection. Scalability is achieved as bandwidth usage relates only to the number of packets transmitted, rather than the number of receivers.

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We claim: 1. A method for providing scalable reliable multicast service, comprising: transmitting a group of data packets over a communication medium to a group of receivers designated by a multicast address; and receiving over the communication medium from the group of receivers acknowledgement pa

We claim: 1. A method for providing scalable reliable multicast service, comprising: transmitting a group of data packets over a communication medium to a group of receivers designated by a multicast address; and receiving over the communication medium from the group of receivers acknowledgement packets, each acknowledgement packet representing a failure by one of the receivers to receive a number of the data packets specified by the acknowledgement packet; wherein the communication medium is multiplexed between a first data link for transmitting packets to the receivers, and a second data link for receiving packets from the receivers, the first data link and the second data link each being provided a time period for data transmission of a predetermined duration before yielding the communication medium to the other data link. 2. A method as in claim 1, wherein the communication medium comprises a first data link for transmitting packets to the receivers, and a second data link for receiving packets from the receivers. 3. A method as in claim 1, wherein the communication medium is divided into time slots and wherein, during receiving, each time slot is assigned to the receivers for acknowledging a failure to receive a specified number of data packets. 4. A method as in claim 3, wherein the specified number of data packets not received is implicitly specified by the position of each time slot. 5. A method as in claim 4, wherein a collision detected during receiving in a time slot is deemed to be equivalent to receiving an acknowledgement packet in that time slot. 6. A method as in claim 1, further comprising sending a control packet to the receivers specifying an allocation of the communication medium for transmitting the data packets and for the receivers to send the acknowledgement packets. 7. A method as in claim 1, wherein the data packets include one or more forward error correcting parity packet (FEC) prepared in response to an acknowledgement packet received. 8. A method as in claim 7, wherein the number of FEC parity packets prepared corresponds to the largest number of data packets failed to be received by a receiver, as indicated by the acknowledgement packets received. 9. A method as in claim 7, further comprising storing the data packets and the FEC parity packets in a multicast buffer until a sufficient number of data packets and FEC parity packets are deemed received by the receivers. 10. A method as in claim 1, further comprising transmitting one or more forward error correcting parity packet (FEC) proactively in anticipation of failure by the receivers to receive one or more of the data packets. 11. A method as in claim 1, wherein the data packets include data packets of a plurality of multicast messages. 12. A method as in claim 1, wherein each time period is divided into a plurality of time slots. 13. A method as in claim 12, wherein the time slots in the first data link is allocated to the data packets of the multicast messages in a manner that gives preference to multicast messages being submitted for transmission at earlier times. 14. A method as in claim 13, wherein the data packets in one of the multicast messages comprise both data packets to be transmitted and forward error correction (FEC) parity packets. 15. A method as in claim 14, further comprising determining the number of FEC parity packets to be sent based upon the highest number of failures to receive represented by the acknowledgement packets. 16. A method as in claim 1, further comprising receiving a positive acknowledgement package from a selected one of the receivers. 17. A method for providing scalable reliable multicast service, comprising: receiving a group of data packets transmitted by a sender over a communication medium, the data packets being transmitted to a group of receivers designated by a multicast address; and transmitting over the communication medium an acknowledgement packet representing a failure to receive a number of the data packets specified by the acknowledgement packet; wherein the communication medium is multiplexed between a first data link for transmitting packets from the sender to the receivers, and a second data link for transmitting packets from the receivers to the sender, the first data link and the second data link each being provided a time period for data transmission of a predetermined duration before yielding the communication medium to the other data link. 18. A method as in claim 17, wherein the communication medium comprises a first data link for transmitting packets from the sender to the receivers, and a second data link for transmitting packets from the receivers to the sender. 19. A method as in claim 17, wherein the communication medium is divided into time slots and wherein each time slot allocated for transmitting an acknowledgement packet is shared by the receivers for acknowledging a failure to receive a specified number of data packets. 20. A method as in claim 19, wherein the specified number of data packets not received is implicitly specified by the position of the time slot. 21. A method as in claim 20, wherein a collision detected by the sender during a time slot in which an acknowledgement packet is transmitted is deemed to be equivalent to receiving an acknowledgement packet in that time slot. 22. A method as in claim 17, further comprising receiving a control packet from the sender specifying an allocation of the communication medium for transmitting the data packets and for the receivers to send the acknowledgement packets. 23. A method as in claim 17, wherein the data packets include one or more forward error correcting parity packet (FEC) prepared in response to an acknowledgement packet received. 24. A method as in claim 23, wherein the number of FEC parity packets expected to be received corresponds to the largest number of data packets failed to be received by a receiver, as indicated by the acknowledgement packets received. 25. A method as in claim 23, further comprising storing the data packets and the FEC parity packets received in a multicast buffer until a sufficient number of data packets and FEC parity packets are received. 26. A method as in claim 17, further comprising transmitting an acknowledgement packet proactively in anticipation of failure to receive one or more of the data packets. 27. A method as in claim 17, wherein the data packets include data packets of a plurality of multicast messages. 28. A method as in claim 17, wherein each time period is divided into a plurality of time slots. 29. A method as in claim 28, wherein the time slots in the first data link is allocated to the data packets of the multicast messages in a manner that gives preference to multicast messages being submitted for transmission by sender at earlier times. 30. A method as in claim 29, wherein the data packets in one of the multicast messages comprise both data packets to be transmitted and forward error correction (FEC) parity packets.