Downlink Based Intercell Time Synchronization Using Maximum Likelihood Estimation

A method to establish a time synchronization for base stations in a cellular network is derived based on the maximum likelihood estimation principle. Its performance is analyzed and compared to a heuristic technique from the literature. The main feature of these synchronization algorithms is that a time synchronization of the base stations is achieved by measurements from the users in the downlinks that are associated to the base stations. The steady-state is reached after a low number of iterations and a low residual error is obtained. The good accuracy allows the application of this algorithm in the context of single frequency networks (SFN), where a high degree of time-synchronization between participating base stations is required.