Theory of NRZ transmission control

Summary form only given. In this work, we extend the guiding center approach, that was previously used for soliton transmissions, to the analysis of NRZ systems. Whenever the transmission wavelength is set slightly below the average zero-dispersion value of the fiber link (i.e., the weak group velocity dispersion is normal), one may introduce an approximate description of the NRZ pulse distortion that is based on the so-called Whitham averaging method. We obtain a quasi-linear system of equations for the evolution of both the NRZ signal amplitude and phase along the link.