How to Rapidly Estimate the Performance of Coherent Systems with any Span Length Heterogeneity and any amplification scheme ?

We propose a model to predict the performance of transmission systems without in-line dispersion compensation for short fiber lengths. This model can predict the Q2 factorWe propose a simple semi-analytical model to predict the performance of transmission systems without in-line dispersion compensation and with heterogeneity of fiber length. Comparing with numerical simulations we show that our model predicts the Q^2 factor with an accuracy of 0.4 dB .with an accuracy of 0.5 dB for systems with different fiber lengths and any amplification scheme.