Patent ID: 6957072

Claim:
A method of calibrating a mobile station location system in a cellular telecommunications network, the method comprising the steps of: determining a position (z k0 ) of a mobile station in the telecommunications network assuming no bias error; deriving, concurrently, an approximation of the position (z k ) of a k th mobile station as a function of an n-dimensional vector (b) of unknown biases according to a calibration bias estimation equation b = ⁢ b 0 - { ∑ k = 1 N ⁢ H k T ⁢ P k - 1 ⁢ H k - ⁢ ∑ k = 1 N ⁢ ( H k T ⁢ P k - 1 ⁢ G k ⁡ ( G k ⁢ P k - 1 ⁢ G k ) - 1 ⁢ G k T ⁢ P k - 1 ⁢ H k ) } - 1 ⁢ ( ∑ k = 1 N ⁢ H k T ⁢ P k - 1 ⁡ ( Y k - r ⁡ ( z k0 , b 0 ) ) ) wherein b is an updated estimate of b 0 , b 0 is the apriori value of a bias vector, Y k is a generic m-dimensional measurement related to the k th mobile station, z k is the position of the k th mobile station represented by the column vector (xy), H k is a derivative of r(z,b) with respect to bias and G k is a derivative of the function of r(z,b) with respect to position; and refining the position (z k0 ) of the mobile station, using the updated estimate of b, according to the equation Y k =r ( z k ,b )+ e k where k=1, . . . ,N, and e k is an additive noise term with covariance P k .