Wireless communication system incorporating multicast addressing and method for use

• US 6,141,347 A
• Filed: 03/31/1999
• Issued: 10/31/2000
• Est. Priority Date: 08/26/1998
• Status: Expired due to Term

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Shaughnessy, Mark, Mathis, James E., Kumar, Surender, DeRango, Mario F., Patel, Bhavesh G.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): VANDERPUYE, KENNETH N
• Application Number:
  US09/283,121
• Time in Patent Office: 580 Days
• Field of Search: 455/518, 455/519, 455/426, 455/520, 370/312, 370/390, 370/432, 370/338, 370/400, 370/401, 370/465, 370/349, 340/825.47
• US Class Current: 370/390
• CPC Class Codes: H04W 84/08 Trunked mobile radio systems

Abstract

A wireless communication system 200 comprises a connectionless packet network 201 coupled to a plurality of sites 203-208 that are in wireless communication with a plurality of subscriber units 210-217 logically arranged into a plurality of talk groups having corresponding talk group identifications. In one embodiment, each site maintains mappings 220-225 of at least one multicast address to at least one talk group identification. In another embodiment, individual subscriber units maintain such mappings 320. When a subscriber unit affiliates with a given site and talk group (501, 601), the site identifies a multicast address corresponding to the talk group. Based on the multicast address, the site can participate in traffic targeted for the multicast address and, consequently, for the talk group. In this manner, mobility Processing is decentralized, system calability is improved and call setup delays are minimized.

Claims

1. A wireless communication system that includes a plurality of subscriber units arranged into a plurality of talk groups, wherein each of the plurality of talk groups is identified by a corresponding talk group identification, the wireless communication system comprising:

a connectionless packet network that supports at least one multicast address; and

a plurality of sites, operably coupled to the connectionless packet network, that provides wireless communications with the plurality of subscriber units, and that each maintains a mapping of at least one talk group identification to the at least one multicast address.

2. The wireless communication system of claim 1, the connectionless packet network further comprising:

a wide area network; and

at least one local area network coupled to the wide area network, wherein the at least one local area network is coupled to at least one site of the plurality of sites.

3. The wireless communication system of claim 2, the at least one site of the plurality of sites further comprising a telephone gateway coupled to the connectionless packet network and to a public switched telephone network.

4. The wireless communication system of claim 2, the connectionless packet network further comprising at least one multicast IP router coupled to the wide area network and the at least one local area network.

5. A subscriber unit for use in a wireless communication system comprising a plurality of sites linked together by a packet network and a plurality of subscriber units arranged into talk groups having corresponding talk group identifications, the subscriber unit further comprising:

a transceiver that wirelessly communicates with the plurality of sites;

a processor, coupled to the transceiver; and

means, coupled to the processor, for maintaining a mapping of at least one talk group identification to at least one multicast address, wherein the packet network supports the at least one multicast address.

6. A site for use in a wireless communication system comprising a plurality of sites linked together by a packet network and a plurality of subscriber units arranged into talk groups having corresponding talk group identifications, the site further comprising:

at least one base station that wirelessly communicates with the plurality of subscriber units;

a controller, coupled to the at least one base station, comprising means for maintaining a mapping of at least one talk group identification to at least one multicast address, wherein the packet network supports the at least one multicast address.

7. The site of claim 6, further comprising:

means, coupled to the means for maintaining the mapping, for identifying a multicast address corresponding to a talk group identification received via the at least one base station from a subscriber unit; and

means, coupled to the means for identifying the multicast address, for transmitting, to the packet network, a message comprising the multicast address requesting reconfiguration of the packet network such that the site at least receives outbound traffic identified by the multicast address.

8. The site of claim 7, further comprising means, coupled to the means for identifying, for transmitting, to the packet network, a message comprising the multicast address requesting reconfiguration of the packet network such that the site does not subsequently receive outbound traffic identified by the multicast address.

9. In a wireless communication system comprising a plurality of sites and a plurality of subscriber units arranged into a plurality of talk groups, the plurality of sites linked together by a packet network, a method comprising the steps of:

transmitting, to a site of the plurality of sites, an affiliation message comprising a talk group identification corresponding to a talk group of the plurality of talk groups;

identifying a multicast address corresponding to the talk group identification; and

transmitting to the site, a message, comprising the multicast address that causes the site to request reconfiguration of the packet network and consequently at least receive outbound traffic identified by the multicast address.

10. The method of claim 9, further comprising the step of receiving, from the site, traffic targeted to the talk group.

11. The method of claim 9, further comprising the step of transmitting, to the site, traffic targeted to the talk group.

12. In a wireless communication system comprising a plurality of sites and a plurality of subscriber units arranged into a plurality of talk groups, the plurality of sites linked together by a packet network, a method for a site of the plurality of sites to register a subscriber unit of the plurality of subscriber units with a talk group of the plurality of talk groups, the method comprising the steps of:

receiving, from the subscriber unit, an affiliation message comprising a talk group identification corresponding to the talk group;

identifying a multicast address corresponding to the talk group identification; and

transmitting, to the packet network, a message comprising the multicast address requesting reconfiguration of the packet network such that the site at least receives outbound traffic identified by the multicast address.

13. The method of claim 12, wherein the step of identifying further comprises receiving the multicast address from the subscriber unit.

14. The method of claim 12, wherein the steps of identifying the multicast address and transmitting the message to the packet network are performed only when the talk group corresponding to the talk group identification is not currently affiliated with the site.

15. The method of claim 12, further comprising the steps of:

receiving, from the packet network, the outbound traffic identified by the multicast address and targeted to the talk group; and

transmitting the outbound traffic to the subscriber unit based on the talk group identification.

16. The method of claim 12, further comprising the steps of:

receiving inbound traffic identified by the talk group identification and targeted to the talk group from the subscriber unit based on the talk group identification; and

transmitting the inbound traffic to the packet network based on the multicast address.

17. The method of claim 12, further comprising the steps of:

determining that the talk group corresponding to the talk group identification is no longer affiliated with the site; and

transmitting, to the packet network, a message comprising the multicast address requesting reconfiguration of the packet network such that the site does not subsequently receive outbound traffic identified by the multicast address.

18. The method of claim 17, the step of determining further comprising the steps of:

sending pages to subscriber units of the plurality of subscriber units currently affiliated with the site and the talk group; and

determining that the talk group is no longer affiliated with the site when no acknowledgments from the subscriber units are received in response to the pages.

19. The method of claim 17, the step of determining further comprising the steps of:

receiving, from an other site of the plurality of sites, a message indicating that a selected subscriber unit of the plurality of subscriber units has left the site and affiliated with the other site; and

determining that the talk group is no longer affiliated with the site when the selected subscriber unit was a last subscriber unit affiliated with the site and the talk group.

20. The method of claim 17, the step of determining further comprising the steps of:

receiving, from an other site of the plurality of sites, a message comprising a last interaction time stamp corresponding to a selected subscriber unit of the plurality of subscriber units, wherein the last interaction time stamp indicates when the other site last communicated with the selected subscriber unit;

comparing the last interaction time stamp with a time stamp indicating when the site last communicated with the selected subscriber unit; and

determining that the talk group is no longer affiliated with the site when the selected subscriber unit was a last subscriber unit affiliated with the site and the talk group, and when the last interaction time stamp is substantially more recent than the time stamp indicating when the site last communicated with the selected subscriber unit.

21. A communication system comprising:

a connectionless packet network that supports at least one multicast address;

a plurality of sites, operably coupled to the connectionless packet network, arranged and constructed to provide wireless communications with a plurality of subscriber units that are arranged in a plurality of talkgroups each having a corresponding talkgroup identification and such that each site maintains a mapping of at least one talkgroup identification to the at least one multicast address; and

at least one site controller, operably coupled to the connectionless packet network, arranged and constructed to reconfigure the connectionless packet network to at least receive outbound traffic identified by the at least one multicast address.