System and method for estimating cell center position for cell ID based positioning
First Claim
1. A method for estimating a cell location for a cell that provides wireless communication services to a plurality of mobile stations each mobile station having a Satellite Positioning System (“
- SPS”
) receiver operating in a positioning system, the method comprising;
obtaining a mobile station location for each of N mobile stations, where N is greater than 1, having a cell identifier that identifies the cell, each mobile station location being determined using the positioning system; and
calculating an estimated location of a cell center based on a statistical measure of the mobile station location of the N mobile stations in the cell where the statistical measure is a maximum likelihood location,wherein calculating the estimated location of the cell center based on the maximum likelihood location further comprises;
obtaining a variance, σ
tj2, of a true position of the mobile station j relative to a true cell center position;
obtaining an SPS variance, Vj, for each mobile station, j, in the cell,calculating a cell location variance, Vij, of a true position of each mobile station j in the cell relative to the estimated cell center location as a function of σ
tj2 and Vj, andusing the variance, Vij, of each mobile station j of N to determine the maximum likelihood location.
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Accused Products
Abstract
Systems and methods for estimating a cell center location in a wireless communication system having an interface to a satellite positioning system (“SPS”) such as for example, a Geosynchronous Positioning System (“GPS”). The wireless communication system provides service to mobile stations within a cell, each mobile station includes a SPS receiver. Examples of the systems and methods for estimating a cell center location analyze the mobile station locations in a cell as a uniform distribution of mobile station locations and calculate a statistical measure characterizing the mobile station locations as a function of the mobile station locations. In one example, the statistical measure is a maximum likelihood mobile station location. In another example, the statistical measure is the mean mobile station location in the cell. The estimated cell center location may be used to approximate the location of the mobile station during a warm or cold restart of the SPS receiver part of the mobile station.
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Citations
26 Claims
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1. A method for estimating a cell location for a cell that provides wireless communication services to a plurality of mobile stations each mobile station having a Satellite Positioning System (“
- SPS”
) receiver operating in a positioning system, the method comprising;obtaining a mobile station location for each of N mobile stations, where N is greater than 1, having a cell identifier that identifies the cell, each mobile station location being determined using the positioning system; and calculating an estimated location of a cell center based on a statistical measure of the mobile station location of the N mobile stations in the cell where the statistical measure is a maximum likelihood location, wherein calculating the estimated location of the cell center based on the maximum likelihood location further comprises; obtaining a variance, σ
tj2, of a true position of the mobile station j relative to a true cell center position;obtaining an SPS variance, Vj, for each mobile station, j, in the cell, calculating a cell location variance, Vij, of a true position of each mobile station j in the cell relative to the estimated cell center location as a function of σ
tj2 and Vj, andusing the variance, Vij, of each mobile station j of N to determine the maximum likelihood location. - View Dependent Claims (2, 3, 4, 5, 6)
- SPS”
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7. A system for estimating a cell center location in a satellite positioning system (“
- SPS”
) comprising;a SPS server connected to the SPS system to retrieve a plurality of mobile station locations from mobile stations in a cell in a wireless communication system, each mobile station comprising an SPS receiver; a SPS database for storing the plurality of mobile station locations and a cell identifier to identify the cell in which the mobile station is obtaining wireless communications service; and a cell center location estimator for; calculating an estimated cell center location by obtaining N mobile station locations, where N is greater than 1, distributed in a cell i and calculating a statistical measure of the mobile station locations, where the statistical measure is a maximum likelihood mobile station location, determining distances between the estimated cell center location and each of the N mobile stations in the cell, determining an initial cell radius by determining the distance between the estimated cell center location and the mobile station that is farthest away from the estimated cell center location, determining a minimized radius r1 as P % of the initial cell radius, determining if P % of the N mobile stations in the cell are located within a circle defined by r1, and if P % of the N mobile stations in the cell are located within a circle defined by r1, then determining a new estimated cell center location based on a maximum likelihood location of the P % of the N mobile stations. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
- SPS”
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15. A non-transitory computer readable medium having programmed instructions for operation in a wireless communication system that uses a satellite positioning system (“
- SPS”
), the computer readable medium comprising;a SPS database interface for retrieving data relating to a plurality of mobile stations in a cell of the wireless communications system, the data including, for each mobile station, a mobile station location and a cell identifier to identify the cell in which the mobile station is obtaining wireless communications service; and a plurality of programmed instruction for; calculating an estimated cell center location by obtaining N mobile station locations, where N is greater than 1, distributed in a cell i and calculating a statistical measure of the mobile station locations, where the statistical measure is a maximum likelihood mobile station location, determining distances between the estimated cell center location and each of the N mobile stations in the cell, determining an initial cell radius by determining the distance between the estimated cell center location and the mobile station that is farthest away from the estimated cell center location, determining a distance between the estimated cell center location and the mobile station that is closest to a radius r1 that defines a circle containing P % of the N mobile stations in the cell, and determining a new estimated cell center location based on the maximum likelihood location of the P % of the N mobile stations. - View Dependent Claims (16, 17, 18, 19, 20)
- SPS”
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21. An apparatus in a satellite positioning system (“
- SPS”
) comprising;a first interface to a SPS database for retrieving from storage in the SPS database a plurality of mobile station locations corresponding to a plurality of mobile stations operating in a cell of the wireless communication system and a cell identifier to identify the cell in which the mobile station is obtaining wireless communications service; and a cell center location estimator for; calculating an estimated cell center location by obtaining N mobile station locations, where N is greater than 1, distributed in a cell i and calculating a statistical measure of the mobile station locations, where the statistical measure is a maximum likelihood mobile station location, and testing the mobile station locations to determine if the mobile stations are clustered by; determining an initial cell radius, defining a plurality of circles having radii less than the initial cell radius with centers at random locations in the cell, determining if each of the plurality of circles defines an area containing a cluster of uniformly distributed mobile station locations, and for each of the plurality of circles that defines a cluster of uniformly distributed mobile station locations, determining an estimated cluster center location based on a maximum likelihood location of the mobile stations in the cluster. - View Dependent Claims (22, 23, 24, 25, 26)
- SPS”
Specification