A soft maximum likelihood technique for time delay recovery

Time delay synchronization is crucial for the reception quality in digital transmission systems. In this contribution, we consider a maximum likelihood approach and incorporate a soft-demapper to improve the synchronization performance. In particular, the proposed scheme allows to update the time delay at each symbol with an adaptive loop using the Log-Likelihood Ratio (LLR) of each bit provided by the demapper. Simulation results show that the proposed approach provides improvements compared to non data aided approach while avoiding data aided approach overhead.