Satellite-based cellular telecommunications system utilizing a multiple registration location register

• US 5,890,062 A
• Filed: 05/16/1996
• Issued: 03/30/1999
• Est. Priority Date: 05/16/1996
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Courtney, William F., Reisig, Carl F.
• Primary Examiner(s): Urban, Edward F.
• Application Number:
  US08/648,901
• Time in Patent Office: 1,048 Days
• Field of Search: 455/428, 455/430, 455/432, 455/433, 455/435, 455/448, 455/12.1, 455/456
• US Class Current: 455/428
• CPC Class Codes: H04B 7/18545 Arrangements for managing station mobility, i.e. for station registration or localisation
• CPC Class Codes: H04B 7/18556 using a location database
• CPC Class Codes: H04B 7/1856 for call routing

Abstract

A satellite based telecommunications system having a multiple registration location register which enables a terminal to register with more than one earth station simultaneously, without any particular one of the earth stations knowing that the terminal is registered elsewhere. The multiple registration location register receives the registration information from each of the earth stations and records the information. This information is used by the multiple registration location register to re-route calls to an earth station that is providing coverage for the terminal. The multiple registration location register may consider many system factors, including satellite to earth station connectivity and satellite to terminal connectivity, in determining to which earth station it should route calls.

Claims

1. A satellite-based telecommunications system comprising:

a plurality of non-geostationary satellites;

a terminal;

a first earth station communicatively accessible to said terminal via a first of said plurality of non-geostationary satellites;

a second earth station communicatively accessible to said terminal via a second of said plurality of non-geostationary satellites; and

a multiple registration location register storing registration information identifying said first and second earth stations as being communicatively accessible to said terminal, said multiple registration location register being communicatively coupled to said first and second earth stations;

said multiple registration location register receiving routing information designating a call to be sent to said terminal through said first earth station via said first non-geostationary satellite, said multiple registration location register rerouting said call through said second earth station via said second non-geostationary satellite.

2. The satellite-based telecommunications system of claim 1 wherein said first earth station is communicatively accessible to said terminal via said one of said plurality of satellites.

3. The satellite-based telecommunications system of claim 2 wherein said first earth station is communicatively accessible to said terminal via another of said plurality of satellites.

4. The satellite-based telecommunications system of claim 1 wherein said first earth station is communicatively inaccessible to said terminal.

5. A cellular telecommunications system comprising:

a plurality of earth stations, each having a visitor location register;

a terminal, said terminal registered with each of the visitor location registers;

a gateway, said gateway having a home location register, said home location register storing information sufficient to enable the gateway to route calls received by said home location register intended for the terminal to a specific one of said plurality of earth stations;

a multiple registration location register in a communication path between said gateway and the specific one of said plurality of earth stations, said multiple registration location register storing information sufficient to route calls received by said multiple registration location register intended for the terminal to any one of said plurality of earth stations; and

wherein said multiple registration location register re-routes a call sent by said gateway to another of said plurality of earth stations so that the call proceeds to the terminal via said another one of said plurality of earth stations.

6. In a satellite-based cellular telecommunications system comprising a terminal, a gateway having a home location register, a first earth station having a first visitor location register, a second earth station having a second visitor location register, a plurality of satellites, a multiple registration location register, and a public switch telephone network, a method of routing calls from the public switch telephone network to the terminal, said method comprising the steps of:

registering by the terminal with the first visitor location register of the first earth station;

communicating by the first earth station first registration information to the home location register;

receiving and storing by the multiple registration location register the first registration information;

receiving and storing by the home location register the first registration information;

registering by the terminal with the second visitor location register of the second earth station;

communicating by the second earth station second registration information to the home location register;

intercepting and storing by the multiple registration location register the second registration information;

receiving by the gateway a call from the public switch telephone network intended for the terminal;

attempting to route by the gateway the call to the first earth station;

intercepting by the multiple registration location register the routed call;

re-routing by the multiple registration location register the routed call to the second earth station; and

forwarding by the second earth station the re-routed call to the terminal via one of the plurality of satellites.

7. A cellular telecommunications system comprising:

multiple mobile-services switching centers, each having an associated visitor location register;

a plurality of antenna providing radio coverage, said plurality being divided into sub-sets of antennas forming location areas, each location area having a unique location area identification, said location areas being divided into sub-sets of location areas, each location area sub-set being supported by a different mobile-services switching center and its associated visitor location register;

a terminal, said terminal within the coverage area of one of the location areas of the cellular telecommunications system;

said terminal monitoring location area identification information and supporting visitor location register identification information being broadcast within the location area, said terminal storing the location area identification of the location area in which coverage is being provided and the identity of the visitor location register of the mobile-services switching center supporting said location area, said terminal registering with the visitor location register of the mobile-services switching center supporting that location area, said terminal receiving from said visitor location register a unique terminal identification, and said terminal storing said terminal identification in association with said location area identification and said visitor location register identification;

said terminal continuing to monitor location area identification information and supporting visitor location register identification information being broadcast within the location area, and said terminal identifying that said location identification information remains the same, but supporting visitor location register identification information has changed due to network coverage changes;

said terminal registering with the supporting visitor location register of the mobile-services switching center now providing coverage of said location area, and said visitor location register assigning a new unique terminal identification to said terminal;

said terminal storing the new terminal identification along with the said location area identification and the identification of the new visitor location register supporting said location area, said terminal maintaining storage of the previously assigned terminal identification and its associated location area identification and supporting visitor location registration identification;

said terminal monitoring location area identification information and supporting visitor location register identification information being broadcast within the location area, said terminal able to determine which of the multiple visitor location register identifications said terminal has stored is identical to the visitor location register identification being broadcast, said terminal selecting the unique terminal identification associated with the visitor location register identification being broadcast, said terminal using said selected unique terminal identification for communication with said cellular telecommunications system during the period it remains within the coverage of said location area and supporting visitor location register.

8. A cellular telecommunications system comprising:

multiple mobile-services switching centers, each having an associated visitor location register;

a plurality of antenna providing radio coverage, said plurality being divided into sub-sets of antennas forming location areas, each location area having a unique location area identification, said location areas being divided into sub-sets of location areas, each location area sub-set being supported by a different mobile-services switching center and its associated visitor location register;

a terminal, said terminal within the coverage area of one of the location areas of the cellular telecommunications system;

said terminal monitoring location area identification information and supporting visitor location register identification information being broadcast within the location area, said terminal storing the location area identification of the location area in which coverage is being provided and the identity of the visitor location register of the mobile-services switching center supporting said location area, said terminal registering with the visitor location register of the mobile-services switching center supporting that location area, said terminal receiving from said visitor location register a unique terminal identification, and said terminal storing said terminal identification in association with said location area identification and said visitor location register identification;

said terminal continuing to monitor location area identification information and supporting visitor location register identification information being broadcast within the location area, and said terminal identifying that said location identification information and supporting visitor location register identification information has changed due to terminal movement into the coverage area of a new mobile-services switching center and its associated visitor location register;

said terminal identifying the location area identification of the new location area in which coverage is being provided, said terminal registering with the supporting visitor location register of the mobile-services switching center supporting said new location area, and said visitor location register assigning a new unique terminal identification to said terminal;

said terminal storing the new terminal identification along with the said location area identification and the identification of the new visitor location register supporting said location area, said terminal maintaining storage of the previously assigned terminal identification and its associated location area identification and supporting visitor location registration identification;

said terminal monitoring location area identification information and supporting visitor location register identification information being broadcast within the location area, said terminal able to determine which of the multiple location area identifications and associated visitor location register identifications said terminal has stored is identical to the location area identification and visitor location register identification being broadcast, said terminal selecting the unique terminal identification associated with the location area identification and visitor location register identification being broadcast, said terminal recognizing said location area identification and visitor location register identification have changed from the last previous identifications monitored by the terminal, said terminal using said selected unique terminal identification and validating its registration with said selected visitor location register, said terminal using said unique terminal identification for communication with said cellular telecommunications system during the period it remains within the coverage of said location area;

or, said terminal using said selected unique terminal identification and attempting to validate its registration with said selected visitor location register, said selected visitor location register rejecting said terminals validation, said terminal erasing said selected unique terminal identification and its associated location area identification and visitor location register identification information from storage, said terminal then newly registering with said visitor location register.