Performance modeling of optical transmission systems through pearson fitting and multicanonical Monte-Carlo simulations

In this paper we propose and compare two different methods, based either on multicanonical Monte-Carlo (MMC) simulations or Pearson fitting, for performance evaluation of realistic wavelength-division-multiplexed (WDM) optical transmission systems. Both methods are able to account for linear and nonlinear propagation effects, and can be applied to any modulation format. As regards MMC, we estimate the distribution of the received sample, accounting for noise, inter-symbol interference (ISI) and inter-channel nonlinearities, by adopting a combined noise and pattern perturbation method. As an alternative to simulations, Gaussian or chi-square fitting techniques have been proposed in the literature. Anyway, none of them is able to provide accurate performance estimation for both on-off keying (OOK) and differential (quadrature) phase-shift keying (D(Q)PSK) modulations. In this work we show that the pdf of the received sample is well approximated by Pearson distributions in all the above-mentioned cases. Pearson distributions are completely determined by their first four moments, which can be estimated by standard Monte Carlo (MC) simulations with less computational burden than typically needed by the MMC method. Finally, for each modulation format, we assess the accuracy of the various fitting techniques by comparing the fitted distributions with those obtained by either MMC simulations in the nonlinear propagation regime, or exact analytical methods in the linear propagation regime.