A class of blind phase recovery techniques for higher order QAM modulations: estimators and bounds

Abstract—This letter proposes a class of blind feedforward carrier-phase estimators for higher order quadrature ampli-tude-modulated transmissions. As an extension of the Viterbi and Viterbi (V&V) estimator, a constellation-dependent optimal matched nonlinear estimator is derived such that its asymptotic variance is minimized. The asymptotic variances of the optimal matched and V&V estimators are established in closed-form expressions and compared. Computer simulations are presented to corroborate the theoretical performance analysis. Index Terms—Asymptotic variance, carrier-phase recovery, QAM constellations. I