Patent ID: 7706814
Filing Date: 2010-04-27
Classification: G01S

Abstract:
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.