Low Complexity FFT-Based Frequency Offset Estimation for M-QAM Coherent Optical Systems

摘要

Frequency offset estimation algorithms for M-ary quadrature amplitude modulation based on the maximization of the periodogram of fourth-power samples have been investigated. In this letter, a low complexity estimation algorithm using interpolated discrete Fourier transform approach is introduced to replace the gradient descent (GD) or the chirp transform (CZT) methods. The numerical simulations and complexity analysis demonstrate that the proposed estimator has much lower computational complexity than that of GD and CZT without performance degradation.