Geolocation responsive radio telecommunication system and method therefor

• US 5,500,648 A
• Filed: 08/11/1993
• Issued: 03/19/1996
• Est. Priority Date: 08/11/1993
• Status: Expired due to Term

• Current Assignee: CDC Propriete Intellectuelle
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Maine, Kristine P., Olds, Keith A., Davieau, Gerald J.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): PHAN, DAO LINDA
• Application Number:
  US08/105,730
• Time in Patent Office: 951 Days
• Field of Search: 342/352, 342/356, 342/357, 364/459, 455/13.2
• US Class Current: 342/357.78
• CPC Class Codes: G01S 5/0027 of actual mobile position, i.e. position determined on mobile
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial

Abstract

A radio telecommunication system includes a number of satellites in low earth orbits. Any number of subscriber units communicates with the satellites. A single subscriber unit communicates with a single satellite using electromagnetic signals so that a measurement processor can obtain Doppler component, propagation duration, and real time measurements of the signals. A location processor converts these measurements into a geographic location with respect to the earth. A service processor determines which qualifications to apply to communication services offered by the system. These qualifications are based on the subscriber unit'"'"'s location. A call processor carries out the qualifications when requests to setup calls involving the subscriber unit are received by the system and during calls involving the subscriber unit.

Claims

1. A method of operating a radio telecommunication system having at least one satellite moving in an orbit around the earth and having at least one subscriber unit located proximate the earth'"'"'s surface, said method comprising the steps of:

determining a Doppler component of an electromagnetic signal traveling between said satellite and said subscriber unit;

determining a location of said subscriber unit relative to the earth in response to said Doppler component; and

granting access to communication services provided by said radio telecommunication system for said subscriber unit in response to said location.

2. A method of operating a radio telecommunication system as claimed in claim 1 additionally comprising the step of determining a duration for which an electromagnetic signal travels between said satellite and said subscriber unit so that said location is determined in response to said Doppler component and said duration.

3. A method of operating a radio telecommunication system as claimed in claim 1 wherein:

said satellite movement causes a nadir direction of said one satellite to intersect the earth along a ground track of said satellite; and

said determining a location step comprises the step of resolving upon which side of said satellite ground track said subscriber unit resides.

4. A method of operating a radio telecommunication system as claimed in claim 3 wherein:

a first plurality of cells are projected from said one satellite toward the earth on a first side of said satellite ground track, and a second plurality of cells are projected from said one satellite toward the earth on a second side of said satellite ground track;

said determining a Doppler component step comprises the step of engaging in communications between said one satellite and said one subscriber unit; and

said resolving step comprises the step of determining whether said communications take place in one of said first plurality of cells or in one of said second plurality of cells.

5. A method of operating a radio telecommunication system as claimed in claim 1 wherein said granting access step comprises the steps of:

identifying a jurisdiction within which said location resides;

enabling communication services provided by said telecommunication system to said subscriber unit if said location resides within a first one of said jurisdictions; and

denying said subscriber unit access to communication services provided by said telecommunication system if said location resides within a second one of said jurisdictions.

6. A method of operating a radio telecommunication system as claimed in claim 1 wherein:

said method additionally comprises the step of associating call rates for communication services with jurisdictions;

said method additionally comprises, after said determining a location step, the step of conducting a call involving said subscriber unit; and

said granting access step comprises the step of determining a cost for said call, said cost being determined in response to one of said call rates, said one of said call rates being associated with a jurisdiction within which said location resides.

7. A method of operating a radio telecommunication system as claimed in claim 1 wherein said radio telecommunication system is a cellular system in which cells are projected toward the earth from said one or more satellites, and said cells move relative to the earth, and wherein said method additionally comprises the steps of:

saving data describing said location;

receiving a request to place a call to said subscriber unit; and

routing, in response to said request and said location data, a call set-up message to the one of said cells which covers said location.

8. A method of operating a radio telecommunication system as claimed in claim 1 wherein said determining a location step comprises the steps of:

determining a first location in response to said Doppler component;

estimating potential location error associated with said first location;

comparing said estimated potential location error with a predetermined error;

determining a second Doppler component when said estimated potential location error exceeds said predetermined error; and

determining a second location in response to said Doppler and said second Doppler components when said estimated potential location error exceeds said predetermined error.

9. A method of operating a radio telecommunication system having at least one satellite moving in an orbit around the earth in which a nadir direction of said one satellite intersects the earth along a satellite ground track, and said system having at least one subscriber unit located proximate the earth'"'"'s surface, said method comprising the steps of:

determining a Doppler component of an electromagnetic signal traveling between said satellite and said subscriber unit;

determining a duration for which an electromagnetic signal travels between said satellite and said subscriber unit;

determining two potential positions of said subscriber unit relative to the earth in response to said Doppler component and said duration;

selecting one of said two potential positions as a location for said subscriber unit by resolving upon which side of said satellite ground track said subscriber unit resides; and

granting access to communication services provided by said radio telecommunication system for said subscriber unit in response to said location.

10. A method of operating a radio telecommunication system as claimed in claim 9 wherein:

said radio telecommunication system is a cellular system in which a first plurality of cells are projected from said one satellite toward the earth on a first side of said satellite ground track and a second plurality of cells are projected from said one satellite toward the earth on a second side of said satellite ground track;

said determining a duration step comprises the step of engaging in communications between said one satellite and said one subscriber unit; and

said selecting step comprises the step of determining whether said communications take place in one of said first plurality of cells or in one of said second plurality of cells.

11. A method of operating a radio telecommunication system as claimed in claim 9 wherein said granting access step comprises the steps of:

identifying a jurisdiction within which said location resides;

enabling communication services provided by said telecommunication system to said subscriber unit if said location resides within a first one of said jurisdictions; and

denying said subscriber unit access to communication services provided by said telecommunication system if said location resides within a second one of said jurisdictions.

12. A method of operating a radio telecommunication system as claimed in claim 9 wherein:

said method additionally comprises the step of associating call rates for communication services with jurisdictions;

said method additionally comprises, after said determining a location step, the step of conducting a call involving said subscriber unit; and

said granting access step comprises the step of determining a cost for said call, said cost being determined in response to one of said call rates, said one of said call rates being associated with a jurisdiction within which said location resides.

13. A method of operating a radio telecommunication system as claimed in claim 9 additionally comprising the steps of:

estimating potential location error associated with said location;

comparing said estimated potential location error with a predetermined error; and

repeating said determining steps and said selecting step when said estimated potential location error exceeds said predetermined error.

14. A method of operating a radio telecommunication system as claimed in claim 9 wherein said radio telecommunication system is a cellular system in which cells are projected toward the earth from said one or more satellites, and said cells move relative to the earth, and wherein said method additionally comprises the steps of:

saving data describing said location;

receiving a request to place a call to said subscriber unit; and

routing, in response to said request and said location data, a call set-up message to the one of said cells which covers said location.

15. A radio telecommunication system for providing communication services to users, said system comprising:

a measurement processor configured to determine a Doppler component of an electromagnetic signal traveling between a satellite and a subscriber unit;

a location processor in data communication with said measurement processor, said location processor being configured to determine a location of said subscriber unit relative to the earth in response to said Doppler component; and

a service processor in data communication with said location processor, said service processor being configured to grant access to communication services provided by said radio telecommunication system for said subscriber unit in response to said location.

16. A radio telecommunication system as claimed in claim 15 wherein:

said measurement processor is additionally configured to determine a duration for which an electromagnetic signal travels between said satellite and said subscriber unit; and

said location processor is additionally configured so that said location is determined in response to said Doppler component and said duration.

17. A radio telecommunication system as claimed in claim 15 wherein:

movement of said satellite causes a nadir direction of said satellite to intersect the earth along a satellite ground track; and

said location processor is additionally configured to resolve upon which side of said satellite ground track said subscriber unit resides.

18. A radio telecommunication system as claimed in claim 17 wherein:

said satellite projects a first plurality of cells toward the earth on a first side of said satellite ground track and a second plurality of cells toward the earth on a second side of said satellite ground track;

said satellite and said subscriber unit are mutually configured to engage in communications through any one of said cells; and

said location processor comprises means for determining whether said communications take place in one of said first plurality of cells or in one of said second plurality of cells.

19. A radio telecommunication system as claimed in claim 15 wherein said service processor comprises:

means for identifying a jurisdiction within which said location resides;

means, responsive to said identifying means, for granting said subscriber unit access to communication services if said location resides within a first one of said jurisdictions; and

means, responsive to said identifying means, for denying said subscriber unit access to communication services if said location resides within a second one of said jurisdictions.

20. A radio telecommunication system as claimed in claim 15 additionally comprising:

means for associating call rates for communication services with jurisdictions;

means, responsive to said associating means, for conducting a call involving said subscriber unit; and

means, responsive to said call conducting means, for determining a cost for said call, said cost being determined in response to one of said call rates, said one of said call rates being associated with a jurisdiction within which said location resides.