Method and apparatus for selecting a responder to enable reliable multicast

• US 20040184427A1
• Filed: 03/20/2003
• Published: 09/23/2004
• Est. Priority Date: 03/20/2003
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Cogency Semiconductor, Inc. (Nova Bancorp Group Ltd.)
• Inventors: Green, Christopher, Lynch, Bradley
• Granted Patent: US 8,064,474 B2
• Time in Patent Office: Days
• US Class Current: 370/342
• CPC Class Codes: H04B 2203/5408 using protocols
• CPC Class Codes: H04B 2203/5445 Local network
• CPC Class Codes: H04B 3/542 the information being in digital form
• CPC Class Codes: H04L 12/1863 comprising mechanisms for improved reliability, e.g. status reports arrangements for detecting or preventing errors by carrying supervisory signal the return channel H04L1/16

Abstract

A station to serve as a proxy for responding to a multicast message is selected using dynamically maintained information about other stations communicatively coupled to a shared communications network. The dynamically maintained information is used to select a station having a high probability of replying to the multicast message. Network performance may be further improved by re-selecting proxies when a multicast frame fails to acknowledged.

Claims

1. A method of selecting a proxy station to respond to a multicast message sent from a first station in a shared medium network, the method comprising:

maintaining availability information about the other stations that are identified to the first station in transmissions over the medium;

selecting the proxy to respond to a multicast message using the availability information and predetermined selection criteria; and

updating the availability information associated with the selected proxy if the selected proxy fails to respond to the multicast message within a predefined time limit.

2. The method as claimed in claim 1 wherein:

maintaining availability information comprises receiving physical layer feedback associated with respective ones of the stations, and dynamically updating the availability information when physical layer feedback associated with any one of the other stations is received.

3. The method as claimed in claim 2 wherein selecting the proxy using the predefined selection criteria comprises evaluating the availability information to determine a time since the physical layer feedback was received from each of the other stations.

4. The method as claimed in claim 3 wherein evaluating the availability information comprises determining at least one of:

a quality of transmission indicated by the respective station;

a status of the respective station; and

, a time since the respective station has successfully transmitted a message to another station communicatively coupled to the shared medium network.

5. The method as claimed in claim 4 wherein maintaining the availability information further comprises prompting the other stations for the physical layer feedback if the physical layer feedback is not received within a predetermined time.

6. The method as claimed in claim 2 wherein the medium provides multiple independent channels and receiving the physical layer feedback comprises receiving an identification of which of the independent channels should be selected for use when the first station communicates with the respective other station.

7. The method as claimed in claim 6 wherein the medium is used to convey orthogonal frequency division multiplexed (OFDM) channels modulated using a modulation technique, and the receiving of the identification comprises receiving a modulation map.

8. The method as claimed in claim 1 wherein:

maintaining the availability information comprises monitoring the shared medium to track addresses of stations that successfully send a message to another station; and

logging information regarding a time of the successful transmission.

9. The method as claimed in claim 8 wherein selecting the multicast proxy further comprises selecting a station that most recently successfully transmitted a message to another station.

10. The method as claimed in claim 1 wherein the updating comprises:

determining whether the multicast proxy has failed to respond to the multicast message after a given number of attempted transmissions; and

updating the availability information associated the station selected as the multicast proxy to indicate that the station should not be used as a multicast proxy until a subsequent transmission over the shared medium provides new physical layer feedback which indicates that the station can be used as a multicast proxy.

11. The method as claimed in claim 10 further comprising updating the availability information associated with the station when the physical layer feedback associated with the station is received.

12. A data processing system comprising hardware and software means for carrying out the method claimed in claim 1.

13. A data processing system comprising hardware and software means for carrying out the method claimed in claim 10.

20. An article comprising:

a computer readable modulated carrier signal; and

means embedded in the signal for establishing the method claimed in claim 1.

14. A station communicatively coupled with a plurality of other stations by a shared communications medium, the station comprising:

a proxy selection procedure adapted to maintain availability information about the other stations that are communicatively coupled to the shared communications medium, use the availability information to select a one of the other stations to serve as a multicast proxy to respond to a multicast message, and update the availability information associated with the station selected as the multicast proxy, if the multicast proxy fails to respond to the multicast message within a predefined period of time.

15. The station as claimed in claim 14 wherein:

the proxy selection procedure is adapted to maintain the availability information using physical layer feedback received from the other stations, and to select the proxy using predefined selection criteria, including a time since physical layer feedback was received from the respective other stations.

16. The station as claimed in claim 15 wherein the proxy selection procedure is further adapted to select the other station to serve as the multicast proxy using at least one of a tone map provided by the other station;

a status of the station; and

, a time since the other station has transmitted or acknowledged receipt of received a message.

17. The station as claimed in claim 14 wherein:

maintaining the availability information further comprises monitoring the shared communications medium to track addresses of stations that successfully transmit messages, logging information regarding a time of the successful transmission, and selecting one of the other stations that has most recently sent a message successfully received by another of the stations.

18. The station as claimed in claim 14 wherein the proxy selection procedure is adapted to update the availability information after determining that the proxy has failed to respond to the multicast message after a predetermined number of attempted transmissions, and to update the availability information associated with the station selected to serve as the multicast proxy to indicate that the station should not be selected again unless a subsequent transmission indicates that the station can be used as a multicast proxy.

19. The station as claimed in claim 18 wherein the proxy selection procedure is further adapted to update the availability information associated with the station selected as the multicast proxy when physical layer feedback associated with the station is received.

21. An article comprising:

a computer readable modulated carrier signal; and

means embedded in the signal for establishing the station claimed in claim 14.