A Comparative Study between Iterative Algorithms for TDOA Based Geolocation Techniques in Real UMTS Networks

In this paper, we analyze the Observed Time Difference of Arrival (OTDOA) technique to simultaneously estimate the position of the different user equipments and the relative time difference between Node Bs in real UMTS networks. We concentrate on comparing two methods to solve the nonlinear system of equations, the well-known Gauss-Newton and the Levenberg-Marquardt algorithm. We show this latter method offers better results, providing faster convergence, higher accuracy and more robustness. Finally, a modification to the classical Levenberg-Marquardt algorithm is proposed in order to avoid divergences in that method.