Optimal blind feedforward carrier synchronization for general QAM modulations

This paper introduces a family of optimal blind feedforward estimators for joint estimation of the carrier phase and frequency offset of general quadrature amplitude modulated (QAM) transmissions. The asymptotic (large sample) performance of these estimators is established in closed-form expression. A practical implementation of the proposed optimally matched estimator, which is a computationally efficient approximation of the latter and exhibits negligible performance loss, is also derived. It is shown that the proposed family of constellation-dependent optimal estimators outperforms all the existing carrier synchronizers, and serves as an unifying framework for designing blind feedforward carrier recovery schemes for large QAM modulations. Finally, computer simulations are presented to show the merit of the proposed optimal estimators.