Non-decision-aided carrier frequency offset estimator for digital radio

A low complexity algorithm for feed-forward carrier frequency offset estimation in digital radio receiver is proposed The algorithm is non-decision-aided and derived form the maximum likelihood estimation theory. Reduced complexity estimator is obtained by solving the derived maximum likelihood estimation equation in an approximate way. A new phase unwrapping algorithm is also proposed to extend the estimation range of the estimator. At moderate to high signal-to-noise ratios the estimation range is extended to +/-1/(2MT) for 2 pi /M rotation symmetric constellation. The performance is assessed by computer simulation for digital modulated 4QAM and 16QAM signals.