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Calibration of positioning systems

  • US 6,957,072 B2
  • Filed: 05/03/2001
  • Issued: 10/18/2005
  • Est. Priority Date: 05/03/2000
  • Status: Expired due to Fees
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 b=

    b0-{

    k=1N


    HkT

    Pk-1

    Hk
    -




    k=1N


    (HkT

    Pk-1

    Gk

    (Gk

    Pk-1

    Gk
    )
    -1


    GkT

    Pk-1

    Hk
    )
    }
    -1


    (

    k=1N


    HkT

    Pk-1

    (Yk-r

    (zk0,b0)
    )
    )
    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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