Full-range carrier frequency offset estimation for CO-OFDM based on CMA equalizers

A constant modulus algorithm-(CMA) based carrier frequency offset estimation method for coherent optical orthogonal frequency division multiplexing (CO-OFDM) system is proposed. Theoretical analysis and simulation results indicate that the frequency offset estimation range of the proposed algorithm can achieve [−5.9, +5.9] GHz, and the mean normalized estimation error can be kept under 0.001 even the optical signal-to-noise ratio (OSNR) value is as low as 2 dB.