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System and method for estimating the location of a mobile device

  • US 8,331,953 B2
  • Filed: 05/01/2007
  • Issued: 12/11/2012
  • Est. Priority Date: 05/01/2007
  • Status: Active Grant
First Claim
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1. A method for estimating the location of a first mobile station from a plurality of mobile stations that receive signals from a plurality of base stations, comprising:

  • (a) determining observed time difference of arrival (“

    OTDOA”

    ) values at said first mobile station and at a second mobile station between a first signal received from a first base station and a second signal received from a second base station;

    (b) determining a round trip time (“

    RTT”

    ) values between said first and second mobile stations and said first base station;

    (c) selecting an initial locations for said first and second mobile stations that are within a first and second predetermined areas, respectively;

    (d) determining an estimated base station time offset (“

    BSTO”

    ) using the selected initial locations, the OTDOA and RTT values, and an iterative search algorithm wherein the iterative search algorithm iterates a predetermined number of steps;

    (e) determining an estimated location for said first mobile station jointly with the BSTO;

    (f) storing said estimated location if the estimated location is within a third predetermined area;

    (g) repeating (a) through (f) within a predetermined time interval; and

    (h) determining a calculated location for said first mobile station from the stored estimated locations.

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