Minimum mean square error estimator for mobile location using time-difference-of-arrival measurements

Localisation of mobile station (MS) has now gained considerable attention. It is not possible to further reduce the root mean square error using the existing location methods without additional information. This study proposes a method to improve the accuracy of mobile location using statistical characteristics of MS position as prior information. In this technique, the Chan-Ho method is extended from the maximum likelihood estimator (MLE) to the minimum mean square error estimator (MMSEE). The Cramer-Rao lower bound and theoretical variance of the proposed method are derived. The theoretical proof and simulations show that the proposed MMSEE has the better performance than the MLE.