Calibration of positioning systems
First Claim
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1. A method of calibrating a mobile station location system in a cellular telecommunications network, the method comprising the steps of:
- determining a position (zk0) of a mobile station in the telecommunications network assuming no bias error;
deriving, concurrently, an approximation of the position (zk) of a kth mobile station as a function of an n-dimensional vector (b) of unknown biases according to a calibration bias estimation equation wherein b is an updated estimate of b0, b0 is the apriori value of a bias vector, Yk is a generic m-dimensional measurement related to the kth mobile station, zk is the position of the kth mobile station represented by the column vector (xy), Hk is a derivative of r(z,b) with respect to bias and Gk is a derivative of the function of r(z,b) with respect to position; and
refining the position (zk0) of the mobile station, using the updated estimate of b, according to the equation
Yk=r(zk,b)+ek where k=1, . . . ,N, and ek is an additive noise term with covariance Pk.
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Abstract
Mobile station positioning methods are calibrated using an error bias estimation for refining the determination of the mobile station location which does not require any added hardware to the telecommunications system. The position of the mobile station is calculated assuming no bias errors and a first order approximation of the mobile station position is derived as a function of the bias error. The bias error is then estimated and used to refine the previously calculated mobile station position.
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Citations
16 Claims
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1. A method of calibrating a mobile station location system in a cellular telecommunications network, the method comprising the steps of:
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determining a position (zk0) of a mobile station in the telecommunications network assuming no bias error;
deriving, concurrently, an approximation of the position (zk) of a kth mobile station as a function of an n-dimensional vector (b) of unknown biases according to a calibration bias estimation equation wherein b is an updated estimate of b0, b0 is the apriori value of a bias vector, Yk is a generic m-dimensional measurement related to the kth mobile station, zk is the position of the kth mobile station represented by the column vector (xy), Hk is a derivative of r(z,b) with respect to bias and Gk is a derivative of the function of r(z,b) with respect to position; and
refining the position (zk0) of the mobile station, using the updated estimate of b, according to the equation
Yk=r(zk,b)+ekwhere k=1, . . . ,N, and ek is an additive noise term with covariance Pk. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for calibrating a mobile station location system in a cellular telecommunications network, the system comprising:
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means for determining a position (zk0) of a mobile station in the telecommunications network assuming no bias error;
means for deriving, concurrently, an approximation of the position (zk) of a kth mobile station as a function of an n-dimensional vector (b) of unknown biases according to a calibration bias estimation equation wherein b is an updated estimate of b0,b0 is the apriori value of a bias vector, Yk is a generic m-dimensional measurement related to the kth mobile station, zk is the position of the kth mobile station represented by the column vector (xy), Hk is a derivative of r(z,b) with respect to bias and Gk is a derivative of the function of r(z,b) with respect to position; and
means for refining the position (zk0) of the mobile station using the updated estimate of b, according to the equation
Yk=r(zk,b)+ekwhere k=1, . . . ,N, and ek is an additive noise term with covariance Pk. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification