Optimal blind nonlinear least-squares carrier phase and frequency offset estimation for circular QAM
Additional Document Info
This paper introduces a family of blind feedforward nonlinear least-squares (NLS) estimators for joint estimation of the carrier phase and frequency offset of circular quadrature amplitude modulated (QAM) transmissions. As an extension of the work of Wang et al, a constellation-dependent optimal matched nonlinear estimator is derived to minimize the asymptotic variance on a circular QAM constellation. Conventional monomial estimators as well as practical approximations to the optimal estimator are introduced to conduct a comparative performance study. Finally, computer simulations are presented to confirm the theoretical predictions and to draw conclusions about the best estimation method for implementation in a practical communication system.