Volterra Based Nonlinear Equalization Method for Optical High-order OFDM/OQAM

Optical orthogonal frequency-division multiplexing offset-quadrature amplitude modulation (OFDM/OQAM) system relaxes the orthogonal condition of the sub-carriers from the complexed domain to the real field. When passing through fiber channel, intrinsic imaginary interference (IMI) induced by chromatic dispersion (CD) and polarization mode dispersion (PMD) could be suppressed by using channel estimation method. However, nonlinear induced interference is an important impairment for long haul transmission optical OFDM/OQAM, and could not be equalized directed by using channel estimation method. In this paper, we introduced a simplified Volterra-series expansion based nonlinear transmission model for optical high-order OFDM/OQAM systems for the first time. On this model basis, nonlinear interference could be suppressed evidently with very limited complexities. As shown in numerous Monte Carlo simulation results, system robustness against nonlinear impairment have been significantly promoted owning to the employment of VENE, 200Km maximum transmission distance could be obtained.