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

A low-complexity algorithm for feedforward carrier frequency offset estimation in a digital radio receiver is proposed. The algorithm is non-decision-aided and derived from the maximum likelihood estimation theory. A 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 a 2π/M rotation symmetric constellation. The performance is assessed by computer simulation for digitally modulated 4QAM and 16QAM signals