Time recovery through fusion of inaccurate network timing assistance with GPS measurements

Fusion of inadequate timing information from GPS space vehicles and from a cellular network is studied. Neither of the sources is accurate enough to be used for exact timing alone, but using the time recovery method proposed by the author, exact timing can be eventually derived from the fusion of these sources. Naturally, the positioning accuracy is also positively affected when accurate time is recovered. The proposed method is based on minimization of a quality of fit value. The quality of fit value used in the paper is the sum of squared residuals obtained from a least mean squares based positioning solution, widely used in point-solution type GPS applications. The proposed method is tested and its performance is demonstrated using both simulated and real data.