Method for the location of mobile terminals
First Claim
1. A method of determining the location of a mobile terminal in a given area, the method comprising the steps of:
- including said mobile terminal both in a satellite-based positioning system and in a cellular communications system, whereby said mobile terminal is adapted to receive satellite signals from said satellite-based system and to be covered by at least one cell of said cellular communications system; and
determining at least approximately the coordinates of said mobile terminal based on both satellite signals received from said satellite-based system and information related to said cellular communications system, wherein said coordinates include an altitude coordinate, wherein the step of determining at least approximately the coordinates of said mobile terminal further comprises;
identifying, in said cellular communications system, a plurality of base stations adjacent to said mobile terminal, each said adjacent base station having a respective altitude coordinate;
deriving an estimate of said altitude coordinate for said mobile terminal, wherein deriving the estimate of said altitude coordinate comprises one of i) determining a minimum of said altitude coordinates for said adjacent base stations and using said minimum value as said estimate of said altitude coordinate; and
ii) determining an average value for said respective altitude coordinates of the plurality of adjacent base stations and using said average value as said estimate of the altitude coordinate; and
determining the location coordinates of said mobile terminal using the estimate of said altitude coordinate and information provided by the satellite-based system, wherein the step of determining the location coordinates further comprises;
determining a first set of values for said location coordinates on the basis of said information related to said cellular communications system;
acquiring said satellite signals from said satellite-based system and deriving therefrom an area likely to include the mobile terminal;
providing a new set of values of said location coordinates by;
i) effecting, based on said information related to said cellular communications system, a bi-dimensional positioning of said mobile terminal within said area likely to include the mobile terminal; and
ii) accessing a geographical data base and associating to the bi-dimensional positioning coordinates of said mobile terminal within said area a corresponding value for said altitude coordinate;
determining the distance between said new set of values of said location coordinates and said first set of values of said location coordinates;
comparing said distance with a threshold indicative of the degree of accuracy pursued in the location action; and
if said distance is higher than said threshold, starting an iterative process wherein said area likely to include the mobile terminal is re-defined on the basis of said satellite signals from said satellite-based system and the latest value available for said altitude coordinate and said steps of affecting said bi-dimensional positioning, accessing said geographical data base and associating to the bi-dimensional positioning coordinates of said mobile terminal within said area a corresponding value for said altitude coordinate are repeated, wherein said steps of bi-dimensional positioning are effected over said re-defined area.
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Accused Products
Abstract
The location of a mobile terminal in a given area is determined by including the mobile terminal both in a satellite-based positioning system and in a cellular communications system. The mobile terminal is thus adapted to receive satellite signals from the satellite-based system and to be covered by at least one cell of the cellular communications system. The mobile terminal is configured for determining at least approximately its coordinates, including an altitude coordinate in the area, based on both satellite signals received from the satellite-based system and information related to the cellular communications system. An estimate of the altitude coordinate is derived from the information related to the cellular communications system, whereby satisfactory location performance is ensured also when one or more satellites in the satellite-based system are not visible at the mobile terminal.
11 Citations
17 Claims
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1. A method of determining the location of a mobile terminal in a given area, the method comprising the steps of:
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including said mobile terminal both in a satellite-based positioning system and in a cellular communications system, whereby said mobile terminal is adapted to receive satellite signals from said satellite-based system and to be covered by at least one cell of said cellular communications system; and determining at least approximately the coordinates of said mobile terminal based on both satellite signals received from said satellite-based system and information related to said cellular communications system, wherein said coordinates include an altitude coordinate, wherein the step of determining at least approximately the coordinates of said mobile terminal further comprises; identifying, in said cellular communications system, a plurality of base stations adjacent to said mobile terminal, each said adjacent base station having a respective altitude coordinate; deriving an estimate of said altitude coordinate for said mobile terminal, wherein deriving the estimate of said altitude coordinate comprises one of i) determining a minimum of said altitude coordinates for said adjacent base stations and using said minimum value as said estimate of said altitude coordinate; and
ii) determining an average value for said respective altitude coordinates of the plurality of adjacent base stations and using said average value as said estimate of the altitude coordinate; anddetermining the location coordinates of said mobile terminal using the estimate of said altitude coordinate and information provided by the satellite-based system, wherein the step of determining the location coordinates further comprises; determining a first set of values for said location coordinates on the basis of said information related to said cellular communications system; acquiring said satellite signals from said satellite-based system and deriving therefrom an area likely to include the mobile terminal; providing a new set of values of said location coordinates by; i) effecting, based on said information related to said cellular communications system, a bi-dimensional positioning of said mobile terminal within said area likely to include the mobile terminal; and ii) accessing a geographical data base and associating to the bi-dimensional positioning coordinates of said mobile terminal within said area a corresponding value for said altitude coordinate; determining the distance between said new set of values of said location coordinates and said first set of values of said location coordinates; comparing said distance with a threshold indicative of the degree of accuracy pursued in the location action; and if said distance is higher than said threshold, starting an iterative process wherein said area likely to include the mobile terminal is re-defined on the basis of said satellite signals from said satellite-based system and the latest value available for said altitude coordinate and said steps of affecting said bi-dimensional positioning, accessing said geographical data base and associating to the bi-dimensional positioning coordinates of said mobile terminal within said area a corresponding value for said altitude coordinate are repeated, wherein said steps of bi-dimensional positioning are effected over said re-defined area. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 16)
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9. An apparatus comprising:
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a first receiver adapted to receive satellite signals transmitted in a satellite-based system; a second receiver adapted to receive signals transmitted in at least one cell of a cellular communications system; at least one processing module configured for determining at least approximately the coordinates of a mobile terminal based on both satellite signals received from said satellite-based system and information related to said cellular communications system, wherein said coordinates include an altitude coordinate and said at least one processing module being configured for; identifying, in said cellular communications system, a plurality of base stations adjacent to said mobile terminal, each said adjacent base station having a respective altitude coordinate; deriving an estimate of said altitude coordinate for said mobile terminal, wherein deriving the estimate of said altitude coordinate comprises one of i) determining a minimum of said altitude coordinates for said adjacent base stations and using said minimum value as said estimate of said altitude coordinate; and
ii) determining an average value for said respective altitude coordinates of the plurality of adjacent base stations and using said average value as said estimate of the altitude coordinate; anddetermining the coordinates of said mobile terminal using the estimate of said altitude coordinate and information provided by the satellite-based system; a geographical data base including data base items associated with a given set of bi-dimensional positioning coordinates of said mobile terminal in said area and corresponding values for said altitude coordinate, said at least one processing module being configured for accessing said geographical data base whereby said positioning coordinates as at least approximately determined based on said satellite signals are refined via the information derived from said geographical data base; at least one module configured for; determining a first set of values for said location coordinates on the basis of said information related to said cellular communications system; acquiring said satellite signals from said satellite-based system and deriving therefrom an area likely to include the mobile terminal; and providing a new set of values of said location coordinates by; i) effecting, based on said information related to said cellular communications system, a bi-dimensional positioning of said mobile terminal within said area likely to include the mobile terminal; and ii) accessing said geographical data base and associating to the bi-dimensional positioning coordinates of said mobile terminal within said area a corresponding value for said altitude coordinate; and at least one module configured for; determining the distance between said new set of values of said location coordinates and said first set of values for said location coordinates; comparing said distance with a threshold indicative of the degree of accuracy pursued in the location action; and if said distance is higher than said threshold, starting an iterative process wherein said area likely to include the mobile terminal is re-defined on the basis of said satellite signals from said satellite-based system and the latest value available for said altitude coordinate and said steps of effecting said bi-dimensional positioning, accessing said geographical data base and associating to the bi-dimensional positioning coordinates of said mobile terminal within said area a corresponding value for said altitude coordinate and are repeated, wherein said steps of bi-dimensional positioning is effected over said re-defined area. - View Dependent Claims (10, 11, 12, 13, 14, 15, 17)
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Specification