Performance Analysis of Nonlinear Fiber-Optic in CO-OFDM Systems With High Order Modulations

In this letter, the Johnson S_{U} distribution is utilized for modeling the linear and nonlinear impairments of coherent optical orthogonal frequency-division multiplexing (CO-OFDM) over the fiber-optic channel with higher order modulations. An analytical expression to evaluate the performance of CO-OFDM systems with n-PSK and n-QAM modulations is proposed. The statistical moments of this additive Johnsonian noise are calculated analytically for a dual-polarization system as a function of the input signal and channel parameters. Finally, the symbol error rate is evaluated, comparing it with the estimations obtained through Monte-Carlo simulations.