Low Complexity Iterative Localization of Time-Misaligned Terminals in Cellular Networks

Recently, iterative localization has arisen as a promising approach to localize a Mobile Station (MS) in a cellular system. The conventional geo-location is obtained in a two-step approach: propagation delays are estimated and then the multi-lateration is responsible for the determination of the user position, based on the estimated delays. Iterative localization iterates between the two conventional steps to progressively refine delay estimates based on the position estimate available from the previous iterations. This localization scheme was seen to provide appealing performances compared to the two-step approach. It also seems to be computationally attractive with respect to direct localization that estimates the position using the digitized received signals directly. However, the iterative localization solution developed in literature relies on a strict time synchronization between MS and Base Stations. Moreover, the computational complexity of the iterative approach is not thoroughly compared to two-step and optimal solutions. This paper, therefore, proposes a new iterative localization method able to operate in a cellular system with time-misaligned terminals. We show by means of a detailed complexity analysis that the iterative positioning algorithm is one order of magnitude less complex than direct localization. Simulation results prove that the achievable performance after a few iterations approaches the performance of the direct localization solution.