Low Complexity Blind Carrier Phase Recovery for Probabilistically Shaped QAM

Abstract

We propose a novel two-stage blind carrier phase recovery scheme tailored for probabilistically shaped QAM. Our algorithm is based on modifying the classic ViterbiViterbi (VV) and maximum likelihood (ML) phase estimators by optimizing the blind decisions over the received symbols taking into account the probability distribution of the received signal. Our technique improves the standard VV + ML in all conditions and outperforms the state-of-the-art blind phase search (BPS) algorithm for a constellation entropy ≤4. At the same time our implementation preserves the low complexity of standard VV + ML. This results in a remarkable reduction in complexity of up to a factor thirty compared to BPS.