A maximum-likelihood based joint carrier frequencies estimation for MPSK signal over SIMO channels

In this paper, we investigate the non data aided (NDA) estimation of carrier frequencies and phases for MPSK signals with multiple independent receive antennas, which can be viewed as a generalized single input multiple output (SIMO) system. Signals over generalized SIMO channels, which bear the same information data sequence, may have different carrier frequencies and phases. By exploring the same information buried in the signals between different receive antennas, the performance of NDA estimation of signal parameters could be improved. First, a blind joint carrier frequencies and phases estimator for MPSK signal over SIMO channels is proposed based on maximum-likelihood (ML) principle. Then a particle swarm optimization (PSO) algorithm is used to search the high-dimensional problem space and find the global maximum of the ML function. Finally, simulations verify the benefits of using multiple independent receive antennas in NDA parameters estimation, which indicate that the proposed estimator in SIMO channels improves the performance of carrier frequencies and phases estimation especially at low SNR levels and has a relatively lower SNR threshold than estimators using only one receive antenna.