METHOD FOR THE LOCATION OF MOBILE TERMINALS

• US 20110128184A1
• Filed: 02/07/2011
• Published: 06/02/2011
• Est. Priority Date: 06/17/2003
• Status: Active Grant

• Current Assignee: Telecom Italia S.p.A.
• Original Assignee: Telecom Italia S.p.A.
• Inventors: Cavallo, Davide, Boiero, Luca
• Granted Patent: US 8,629,802 B2
• Time in Patent Office: Days
• US Class Current: 342/357.31
• CPC Class Codes: G01S 19/50 whereby the position solution is constrained to lie upon a particular curve or surface, e.g. for locomotives on railway tracks

Abstract

A location of a mobile terminal in a given area may be determined by including the mobile terminal in a satellite-based positioning system and in a cellular communications system. The approximate coordinates of the mobile terminal may be determined based on both satellite signals received from the satellite-based system and information related to the cellular communication system, where the coordinates include an altitude coordinate. An estimate of the altitude coordinate may be derived from the information related to the cellular communication system. The approximate coordinates may be determined using the estimate of the altitude coordinate and information provided by the satellite-based system by providing an approximate bi-dimensional positioning of the terminal and exploiting the bi-dimensional positioning and the estimate of the altitude coordinate.

Claims

1-80. -80. (canceled)

81. A method of determining the location of a mobile terminal in a given area, 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 communication 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 communication system, wherein said coordinates include an altitude coordinate, and an estimate of said altitude coordinate is derived from said information related to said cellular communication system, wherein the step of determining at least approximately the coordinates of said mobile terminal further comprises;

determining the 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 coordinates further comprises;

providing an approximate bi-dimensional positioning of said terminal on the basis of said information related to said cellular communication system; and

determining said positioning coordinates of said mobile terminal on the basis of said satellite signals by exploiting said bi-dimensional positioning and said estimate of said altitude coordinate, wherein determining said positioning coordinates of said mobile terminal further comprises;

initially determining a search area for positioning coordinates of said mobile terminal based on said satellite signals and said estimate of said altitude coordinate; and

subsequently identifying said positioning coordinates within said search area based on information related to said cellular communication system.

82. The method of claim 81, further comprising the steps of:

providing a geographical data base comprising data base items associated with a given set of bi-dimensional positioning coordinates of said mobile terminal in said area corresponding to values for said altitude coordinate; and

accessing said geographical data base via said mobile terminal whereby said positioning coordinates, as at least approximately determined by said mobile terminal based on said satellite signals, are refined via the information derived from said geographical data base.

83. The method of claim 81, comprising the steps of:

identifying, in said cellular communications system, at least one base station proximate to said mobile terminal, said proximate base station having an associated altitude coordinate; and

using the altitude coordinate of said proximate base station as said estimate of said altitude coordinate.

84. The method of claim 81, comprising the steps of:

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;

determining the minimum of said altitude coordinates for said adjacent base stations; and

using said minimum value as said estimate of said altitude coordinate.

85. The method of claim 81, comprising the steps of:

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;

determining an average value for said respective altitude coordinates over said adjacent base stations; and

using said average value as said estimate of said altitude coordinate.

86. The method of claim 85, comprising the steps of:

performing power measurements providing, for each said adjacent base station, a respective power value for said mobile terminal; and

determining said average value as a weighted average of said respective altitude coordinates values, the weighting being a function of said power values determined for each said adjacent base station.

87. The method of claim 81, wherein said positioning coordinates are determined in an iterative manner by subsequent location steps, a new refined estimate of said altitude coordinate being used at each step in said iterative process.

88. The method of claim 81, comprising the steps of:

defining the search area for said positioning coordinates in the form of a hyperbolic set of points; and

determining said positioning coordinates within said hyperbolic set of points by using said information related to said cellular communication system.

89. The method of claim 82, comprising the steps of:

determining a first set of values for said location coordinates on the basis of said information related to said cellular communication 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 communication 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.

90. The method of claim 89, comprising the steps of:

determining the distance between said new set of values of said location coordinates and said first set of values for said location coordinates; and

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 are repeated, wherein said steps of bi-dimensional positioning are effected over said re-defined area.

91. The method of claim 90, wherein said iterative process comprises the steps of:

determining the distance between the sets of values of said location coordinates as available before and after the current iteration step; and

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, running a further iteration step wherein said area likely to include the mobile terminal is further 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 are further repeated, wherein said step of bi-dimensional positioning is effected over said further re-defined area.

92. The method of claim 81, comprising the step of determining at least approximately said coordinates based on satellite signals received from less than three satellites of said satellite-based system.

93. An apparatus comprising:

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 communication system, wherein said coordinates include an altitude coordinate and said at least one processing module being configured for;

determining the 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 coordinates further comprises;

providing an approximate bi-dimensional positioning of said terminal on the basis of said information related to said cellular communication system; and

determining said positioning coordinates of said mobile terminal on the basis of said satellite signals by exploiting said bi-dimensional positioning and said estimate of said altitude coordinate, wherein determining said positioning coordinates of said mobile terminal further comprises;

initially determining a search area for positioning coordinates of said mobile terminal based on said satellite signals and said estimate of said altitude coordinate; and

subsequently identifying said positioning coordinates within said search area based on information related to said cellular communication system.

94. The apparatus of claim 93, comprising 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 corresponding values for said altitude coordinate, said at least one 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.

95. The arrangement of claim 93, wherein:

said cellular communications system comprises at least one base station proximate to said mobile terminal, said proximate base station having an associated altitude coordinate; and

said at least one module is configured for using the altitude coordinate of said proximate base station as said estimate of said altitude coordinate.

96. The apparatus of claim 93, wherein:

said cellular communications system comprises a plurality of base stations adjacent to said mobile terminal, each said adjacent base station having a respective altitude coordinate; and

said at least one module is configured for using as said estimate of said altitude coordinate one of the minimum of said altitude coordinates for said adjacent base stations and an average value for said respective altitude coordinates over said adjacent base stations.

97. The apparatus of claim 96, wherein said at least one module is configured for performing power measurements providing, for each said adjacent base station, a respective power value for said mobile terminal, and determining said average value as a weighted average of said respective altitude coordinates values, the weighting being a function of said power values determined for each said adjacent base station.

98. The apparatus of claim 93, comprising at least one module configured for determining said positioning coordinates in an iterative process by subsequent location steps, a new refined estimate of said altitude coordinate being used at each step in said iterative process.

99. The apparatus of claim 93, comprising at least one module configured for:

defining the search area for said positioning coordinates in the form of a hyperbolic set of points; and

determining said positioning coordinates within said hyperbolic set of points by using said information related to said cellular communication system.

100. The apparatus of claim 94, comprising 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 communication 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 communication 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.

101. The apparatus of claim 100, comprising 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; and

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 are repeated, wherein said steps of bi-dimensional positioning is effected over said re-defined area.

102. The apparatus of claim 101, comprising at least one module configured for running said iterative process by:

determining the distance between the sets of values of said location coordinates as available before and after the current iteration step; and

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, running a further iteration step wherein said area likely to include the mobile terminal is further 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 are further repeated, wherein said step of bi-dimensional positioning is effected over said further re-defined area.

103. A computer-readable storage medium comprising instructions that when executed by a process perform steps comprising:

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 communication 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 communication system, wherein said coordinates include an altitude coordinate, and an estimate of said altitude coordinate is derived from said information related to said cellular communication system, wherein the step of determining at least approximately the coordinates of said mobile terminal further comprises;

determining the 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 coordinates further comprises;

providing an approximate bi-dimensional positioning of said terminal on the basis of said information related to said cellular communication system; and

determining said positioning coordinates of said mobile terminal on the basis of said satellite signals by exploiting said bi-dimensional positioning and said estimate of said altitude coordinate, wherein determining said positioning coordinates of said mobile terminal further comprises;

initially determining a search area for positioning coordinates of said mobile terminal based on said satellite signals and said estimate of said altitude coordinate; and

subsequently identifying said positioning coordinates within said search area based on information related to said cellular communication system.

104. The computer-readable medium of claim 103, further comprising the steps of:

providing a geographical data base comprising data base items associated with a given set of bi-dimensional positioning coordinates of said mobile terminal in said area corresponding to values for said altitude coordinate; and

accessing said geographical data base via said mobile terminal whereby said positioning coordinates, as at least approximately determined by said mobile terminal based on said satellite signals, are refined via the information derived from said geographical data base.

105. The computer-readable medium of claim 103, comprising the steps of:

identifying, in said cellular communications system, at least one base station proximate to said mobile terminal, said proximate base station having an associated altitude coordinate; and

using the altitude coordinate of said proximate base station as said estimate of said altitude coordinate.

106. The computer-readable medium of claim 103, comprising the steps of:

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;

determining the minimum of said altitude coordinates for said adjacent base stations; and

using said minimum value as said estimate of said altitude coordinate.

107. The computer-readable medium of claim 103, comprising the steps of:

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;

determining an average value for said respective altitude coordinates over said adjacent base stations; and

using said average value as said estimate of said altitude coordinate.

108. The computer-readable medium of claim 107, comprising the steps of:

performing power measurements providing, for each said adjacent base station, a respective power value for said mobile terminal; and

determining said average value as a weighted average of said respective altitude coordinates values, the weighting being a function of said power values determined for each said adjacent base station.

109. The computer-readable medium of claim 103, wherein said positioning coordinates are determined in an iterative manner by subsequent location steps, a new refined estimate of said altitude coordinate being used at each step in said iterative process.

110. The computer-readable medium of claim 103, comprising the steps of:

defining the search area for said positioning coordinates in the form of a hyperbolic set of points; and

determining said positioning coordinates within said hyperbolic set of points by using said information related to said cellular communication system.

111. The computer-readable medium of claim 104, comprising the steps of:

determining a first set of values for said location coordinates on the basis of said information related to said cellular communication 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 communication 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.

112. The computer-readable medium of claim 111, comprising the steps of:

determining the distance between said new set of values of said location coordinates and said first set of values for said location coordinates; and

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 are repeated, wherein said steps of bi-dimensional positioning are effected over said re-defined area.

113. The computer-readable medium of claim 112, wherein said iterative process comprises the steps of:

determining the distance between the sets of values of said location coordinates as available before and after the current iteration step; and

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, running a further iteration step wherein said area likely to include the mobile terminal is further 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 are further repeated, wherein said step of bi-dimensional positioning is effected over said further re-defined area.

114. The computer-readable medium of claim 103, comprising the step of determining at least approximately said coordinates based on satellite signals received from less than three satellites of said satellite-based system.