Blind Mechanism for the Joint Estimation of Frequency Offset and Phase Offset for QAM Modulated Signals

摘要

A mechanism for jointly correcting carrier phase and carrier frequency errors in a demodulated signal. A computer system may receive samples of a baseband input signal (resulting from QAM demodulation). The computer system may compute values of a cost function J over a grid in a 2D angle-frequency space. A cost function value J(θ,ω) is computed for each point (θ,ω) in the grid by (a) applying a phase adjustment of angle θ and a frequency adjustment of frequency ω to the input signal; (b) performing one or more iterations of the K-means algorithm on the samples of the adjusted signal; (c) generated a sum on each K-means cluster; and (d) adding the sums. The point (θ_e,ω_e) in the 2D angle-frequency space that minimizes the cost function J serves an estimate for the carrier phase error and carrier frequency error. The estimated errors may be used to correct the input signal.