Method for an improved linear least squares estimation of a mobile terminal's location under LOS and NLOS conditions and using map information
First Claim
1. A method for localization of a mobile terminal using known positions of a plurality of fixed terminals, comprising:
- at each fixed terminal, receiving a signal from the mobile terminal;
for each fixed terminal, estimating a square of a distance separating the known location for the fixed terminal from the mobile terminal based upon the received signal;
selecting a single reference terminal from the fixed terminals that is closest to the mobile terminal to reduce a mean squared error for the localization of the mobile terminal, the single reference terminal being located at a reference position and corresponding to a squared reference distance to the mobile terminal, the plurality of fixed terminals thereby corresponding to the single reference terminal and a remaining set of fixed terminals;
deriving linear equations from the squared distances, the squared reference distance, the reference location, the known locations for the remaining set of fixed terminals, and a covariance matrix that measures covariances resulting from the linear equation derivation; and
determining the position of the mobile terminal using a location estimator on the linear equations.
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Accused Products
Abstract
A linear least squares (LLS) estimator provides a low complexity estimation of the location of a mobile terminal (MT), using one of the fixed terminals (FTs) as a reference FT to derive a linear model. A method for selecting a reference FT is disclosed, which improves the location accuracy relative to an arbitrary approach to selecting the reference FT. In addition, a covariance-matrix based LLS estimator is proposed in line-of-sight (LOS) and non-LOS (NLOS) environments to further provide accuracy, taking advantage of the correlation of the observations. Different techniques for selecting the reference FT under non-LOS (NLOS) conditions are disclosed. A map-based two-stage LLS estimator assists in selecting the reference FT under NLOS conditions.
10 Citations
16 Claims
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1. A method for localization of a mobile terminal using known positions of a plurality of fixed terminals, comprising:
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at each fixed terminal, receiving a signal from the mobile terminal; for each fixed terminal, estimating a square of a distance separating the known location for the fixed terminal from the mobile terminal based upon the received signal; selecting a single reference terminal from the fixed terminals that is closest to the mobile terminal to reduce a mean squared error for the localization of the mobile terminal, the single reference terminal being located at a reference position and corresponding to a squared reference distance to the mobile terminal, the plurality of fixed terminals thereby corresponding to the single reference terminal and a remaining set of fixed terminals; deriving linear equations from the squared distances, the squared reference distance, the reference location, the known locations for the remaining set of fixed terminals, and a covariance matrix that measures covariances resulting from the linear equation derivation; and determining the position of the mobile terminal using a location estimator on the linear equations. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification