Minimizing the error of time difference of arrival method in mobile networks

Estimating the position of a mobile set is of great importance in new mobile services. However, in most cases, the accuracy should be less than 100 meters. This accuracy is hard to reach especially in urban areas. The main problem is that there are a lot of obstacles like buildings between the BTS and the mobile set. Thus the time measured between BTS and the mobile set is somehow greater than the time it takes the wave to travel directly between two points. This paper introduces an optimized solution for TDOA as one of the most efficient ways for finding the location of a mobile phone. Considering the standards and limitations of both GSM and UMTS, the authors present a solution for optimizing mobile phone positioning. In this new method, the positioning is done via common TDOA methods. Moreover, the non-linear effects of the environment such as non-line of sight error (NLOS) are minimized through comparing the measured data with pre measured points to reduce the error of finding the MS location. The simulations show that compared to direct measurement, the optimized protocol, reduces the error of location method by 33%.