Non-Gaussian statistics of CO-OFDM signals after non-linear optical fibre transmission

In this study, the statistical distribution of the received signal in a coherent optical orthogonal frequency-division multiplexing (CO-OFDM) system with quadrature-phase shift keying modulation in the orthogonal frequency-division multiplexing (OFDM) subcarriers is investigated, and the accuracy and correctness of the Gaussian probability density function (pdf) assumption is analysed. The well-known Anderson–Darling test is utilised to measure the deviation extent of the statistical distribution of the received signal from the Gaussian pdf. Finally, the Johnson ${\rm S}_U$SU-distribution is suggested as a more exact distribution for the statistical modelling of the received signal. After non-linear propagation, its accuracy is assessed through comparison with Monte-Carlo simulations, based on the time-domain split-step Fourier method.