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Location estimation method

  • US 7,715,852 B2
  • Filed: 01/04/2007
  • Issued: 05/11/2010
  • Est. Priority Date: 01/06/2006
  • Status: Expired due to Fees
First Claim
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1. A location estimation method for locating a mobile station (MS) by a plurality of base stations (BS), comprising:

  • analyzing a geometric distribution of the BSs to provide a list of conditional equations;

    allocating virtual BSs having virtual distances to the MS to provide constraint equations; and

    estimating the MS location based on the conditional equations and the constraint equations;

    wherein analysis of the geometric distribution comprises;

    transmitting coordinates of each BS to the MS;

    estimating time-of arrival (TOA) of signals transmitted to or from the BSs to obtain measured distances correspondingly;

    measuring noise level of each transmission to calculate standard deviations of the measured distances;

    generating the conditional equations based on the measured distances and the standard deviations;

    calculating an initial estimate of the MS location based on the standard deviations and coordinates of the BSs;

    determining the virtual distances based on the initial estimate of the MS location, the coordinates of the BSs and a plurality of virtual coefficients each corresponding to a BS; and

    rendering a GDOP contour based on the analysis of the geometric distribution, statistically presenting measurement error distribution of the BSs;

    wherein allocation of the virtual BS comprises;

    observing peak values distributed in the GDOP contour; and

    allocating the virtual BSs to the positions where at least one peak value is causally smoothed away.

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