Abstract:

 A positioning algorithm based on time-of-arrival in a non-line of sight environment is presented. First, a priori knowledge of standard deviation of measurements noise was exploited to decide whether there were non line of sight errors in time-of-arrival measurements. Then a weighted orthogonal polynomial fitting technique was used to correct the measurements contaminated by non-line of sight errors and consequently give the estimation of location of  a mobile station. Finally, mean estimation errors by least squares algorithm and constrained weighted least squares algorithm in line-of-sight environment were calculated and the CramérRao lower bound was also given. Computation results show that the proposed algorithm can effectively reconstruct the range measurements and achieve better location accuracy in a non-line of  sight environment.

Key words: non-line of sight, time-of-arrival, orthogonal polynomial fitting, optimization, location position