System and method for generating a location estimate for a mobile station

• US 7,706,814 B2
• Filed: 08/13/2004
• Issued: 04/27/2010
• Est. Priority Date: 05/12/2004
• Status: Expired due to Fees

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Sillasto, Eero, Spirito, Maurizio
• Primary Examiner(s): Appiah; Charles N
• Assistant Examiner(s): STEPHEN, EMEM O
• Application Number:
  US10/917,470
• Publication Number:
  US 20050255865A1
• Time in Patent Office: 2,083 Days
• Field of Search: 455/404.2, 455/457, 455/456.1, 455/456.3, 455/404.1
• US Class Current: 455/456.5
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

The method generates a location estimate for a mobile station in a wireless communications network. The method includes receiving first measurement data relating to at least one radio link between the mobile station and a first site, and provides a first distance estimate of the mobile station from the first site based on the first measurement data. Second measurement data is received, relating to at least one radio link between the mobile station and a second site and provides a second distance estimate of the mobile station from the second site. First and second intersection points are determined between a circle centered at the first site of a radius corresponding to the first distance estimate, and a circle centered at the second site of the radius corresponding to the second distance estimate. The first and second intersection points lie on opposite sides of a line passing through the first and second sites. At least one of the first and second intersection points are used in the determination of the location estimate.

Claims

1. A method comprising:

receiving first measurement data relating to at least one radio link between a mobile station in a wireless communications network and a first site and providing a first distance estimate of the mobile station from the first site based on the first measurement data;

receiving second measurement data relating to at least one radio link between the mobile station and a second site and providing a second distance estimate of the mobile station from the second site;

determining first and second intersection points between a first circle centered at the first site of a first radius corresponding to the first distance estimate and a second circle centered at the second site of a second radius corresponding to the second distance estimate, said first and second intersection points lying on opposed sides of a line passing through the first and second sites;

generating at least one provisional location estimate for a location of the mobile station using first measurement data relating to the at least one radio link between the mobile station and the first site, and second measurement data relating to the at least one radio link between the mobile station and the second site;

determining using the distances of said first and second intersection points to said at least one provisional location estimate, a probability that the mobile station lies on the same side of the line as each of said first and second intersection points;

selecting at least one of the first and second intersection points based on which side of the line there is a greater probability that the mobile station lies;

using said selected at least one of the first and second intersection points in determining a location estimate; and

generating a location estimate for the mobile station.

2. A method according to claim 1, wherein the determining first and second intersection points comprises determining a first set of intersection points and a second set of intersection points, each set including more than one intersection point.

3. A method according to claim 1, wherein said at least one intersection point is selected to lie on a side of the line on which at least one of the at least one provisional location estimate lies.

4. A method according to claim 1, which further comprises using a weighted single cell location method to generate the at least one provisional location estimate.

5. A method according to claim 1, which further comprises using a weighted single site location method to provide the at least one provisional location estimate.

6. A method according to claim 1, wherein a plurality of provisional location estimates are generated using different location methods.

7. A method according to claim 1, which further comprises determining a distance from at least one of the first and second sites to said at least one of the first and second intersection points, and an orientation of said at least one of the first and second intersection points, with respect to said at least one of the first and second sites.

8. A method according to claim 7, which further comprises using said determined distance and orientation in a location calculation method to generate an improved location estimate.

9. A method according to claim 1, which further comprises determining the distance from said at least one provisional location estimate from each of the first and second sites respectively, and using said distances to determine a probability that the mobile station lies on one or other side of the line.

10. A method according to claim 1, wherein each of the first and second intersection points are associated with respective probabilities that the mobile station lies on their side of the line.

11. A method according to claim 8, which further comprises allocating probabilities to said first and second intersection points and utilizing said probabilities with said determined distance and orientation in said location calculation method.

12. An apparatus comprising:

means for receiving measurement data relating to radio links established between a mobile station in a cellular communications network and each of first and second sites, and providing first and second distance estimates of the mobile station from the first and second sites respectively based on the measurement data;

means for determining first and second intersection points between a first circle centered at the first site of a first radius corresponding to the first distance estimate and a second circle centered at the second site of a second radius corresponding to the second distance estimate, said first and second intersection points lying on opposed sides of a line passing through the first and second sites;

means for generating at least one provisional location estimate for a location of the mobile station using first measurement data relating to the at least one radio link between the mobile station and the first site, and second measurement data relating to the at least one radio link between the mobile station and the second site;

means for determining, using the distances of said first and second intersection points to said at least one provisional location estimate, a probability that each of said first and second intersection points lies on a same side of the line as the mobile station;

means for selecting at least one of the first and second intersection points based on which side of the line there is a greater probability that the mobile station lies;

means for utilizing the selected at least one of the first and second intersection points in determining a location estimate; and

means for generating a location estimate for the mobile station.

13. An apparatus according to claim 12, which comprises means for determining a distance from at least one of the first and second sites to said at least one of the first and second intersection points, and an orientation of said at least one of the first and second intersection points, with respect to said at least one of the first and second sites.

14. An apparatus comprising:

a receiver configured to receive measurement data relating to radio links established between a mobile station in a cellular communications network and each of first and second sites, and to provide first and second distance estimates of the mobile station from the first and second sites respectively based on the measurement data;

an intersection determining unit configured to determine first and second intersection points between a first circle centered at the first site of a first radius corresponding to the first distance estimate and a second circle centered at the second site of a second radius corresponding to the second distance estimate, said first and second intersection points lying on opposed sides of a line passing through the first and second sites;

a provisional location estimate generator configured to generate at least one provisional location estimate for a location of the mobile station using first measurement data relating to the at least one radio link between the mobile station and the first site, and second measurement data relating to the at least one radio link between the mobile station and the second site;

a probability determining unit configured to determine a probability that each of said first and second intersection points lies on a same side of the line as the mobile station, wherein the probability is based on the distances of said first and second intersection points to the at least one provisional location estimate; and

a selector configured to select at least one of the first and second intersection points based on which said of the line there is a greater probability that the mobile station lies;

a determination unit configured to utilize at least one of the first and second intersection points in determining a location estimate,

wherein the apparatus is configured to generate a location estimate for the mobile station.

15. An apparatus according to claim 14, comprising a serving mobile location center.

16. An apparatus according to claim 14, further comprising a distance determining unit configured to determine a distance from at least one of the first and second sites to said at least one of the first and second intersection points, and an orientation of said at least one of the first and second intersection points, with respect to said at least one of the first and second sites.

17. A method comprising:

receiving first measurement data relating to at least one radio link between a mobile station in a wireless communication network and a first site and providing a first distance estimate of the mobile station from the first site based on the first measurement data;

receiving second measurement data relating to at least one radio link between the mobile station and a second site and providing a second distance estimate of the mobile station from the second site;

determining first and second intersection points between a first circle centred at the first site of a first radius corresponding to the first distance estimate and a second circle centred at the second site of a second radius corresponding to the second distance estimate, said first and second intersection points lying on opposed sides of a line passing through the first and second sites;

generating at least one provisional location estimate for a location of the mobile station using first measurement data relating to the at least one radio link between the mobile station and the first site, and second measurement data relating to the at least one radio link between the mobile station and the second site;

selecting at least one of the first and second intersection points based on which side of the line there is a greater probability that the mobile station lies, wherein the selecting said at least one of the first and second intersection points comprises selecting at least one intersection point to lie on a side of the line on which the at least one provisional location estimate lies;

using said selected at least one of the first and second intersection points in determining a location estimate; and

generating a location estimate for the mobile station.

18. An apparatus comprising:

a receiver configured to receive measurement data relating to radio links established between a mobile station in a cellular communications network and each of first and second sites, and to provide first and second distance estimates of the mobile station from the first and second sites respectively based on the measurement data;

an intersection determining unit configured to determine first and second intersection points between a first circle centred at the first site of a first radius corresponding to the first distance estimate and a second circle centred at the second site of a second radius corresponding to the second distance estimate, said first and second intersection points lying on opposed sides of a line passing through the first and second sites;

a provisional location estimate generator configured to generate a provisional location estimate for a location of the mobile station using first measurement data relating to the at least one radio link between the mobile station and the first site, and second measurement data relating to the at least one radio link between the mobile station and the second site;

a selector configured to select at least one of the first and second intersection points based on which side of the line there is a greater probability that the mobile station lies, wherein said at least one intersection point is selected to lie on a side of the line on which the at least one provisional location estimate lies; and

a determination unit configured to utilize at least one of the first and second intersection points in determining a location estimate,

wherein the apparatus is configured to generate a location estimate for the mobile station.

19. A computer program, embodied on a computer readable medium, the computer program configured to control a processor to perform a method comprising:

receiving first measurement data relating to at least one radio link between a mobile station in a wireless communications network and a first site and provide a first distance estimate of the mobile station from the first site based on the first measurement data;

receiving second measurement data relating to at least one radio link between the mobile station and a second site and provide a second distance estimate of the mobile station from the second site;

determining first and second intersection points between a first circle centered at the first site of a first radius corresponding to the first distance estimate and a second circle centered at the second site of a second radius corresponding to the second distance estimate, said first and second intersection points lying on opposed sides of a line passing through the first and second sites;

generating at least one provisional location estimate for a location of the mobile station using first measurement data relating to the at least one radio link between the mobile station and the first site, and second measurement data relating to the at least one radio link between the mobile station and the second site;

determining, using the distances of said first and second intersection points to said at least one provisional location estimate, a probability that the mobile station lies on the same side of the line as each of said first and second intersection points;

selecting at least one of the first and second intersection points based on which side of the line there is a greater probability that the mobile station lies;

using said selected at least one of the first and second intersection points to determine a location estimate; and

generating a location estimate for the mobile station.