Range of Influence of Physical Impairments in Wavelength-Division Multiplexed Systems

In wavelength-division multiplexed (WDM) systems, system performance is adversely affected by severe physical impairments due to fiber loss, dispersion and nonlinearity. Fiber modeling is a prerequisite for the development of physical impairment mitigation techniques to improve system performance. The distance between two interacting symbols in time and wavelength, i.e., the range of influence (RoI) of each physical impairment, plays an important role in the development of these mitigation techniques. This paper develops a two-dimensional (time and wavelength) discrete-time input-output model of WDM systems based on the Volterra series transfer function (VSTF) method. This model takes into account multiple channel effects, fiber loss, and frequency chirp, which are ignored in the current literature. Furthermore, with this model we define coefficients that capture intersymbol interference (ISI), self phase modulation (SPM), intrachannel cross phase modulation (IXPM), intrachannel four wave mixing (IFWM), cross phase modulation (XPM) and four wave mixing (FWM) to characterize the impact of these impairments individually on the system output. By investigating these impairment coefficients, the RoIs for different physical impairments are determined.