Impact of the transmitted signal initial dispersion transient on the accuracy of the GN-model of non-linear propagation

The GN-model neglects the initial signal dispersion transient in the fiber. We show that this circumstance causes the coherent-accumulation GN-model to provide a lower-bound to system performance estimation, typically less than 0.5 dB away from actual, while the simpler incoherent GN-model typically incurs lower performance estimation errors.