Range of Influence and Impact of Physical Impairments in Long-Haul DWDM Systems

In long-haul dense wavelength-division multiplexing (DWDM) systems with periodic dispersion compensation and amplification, system performance is adversely affected by severe physical impairments due to fiber losses, 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. In this paper, we use the Volterra series transfer function (VSTF) method to define impairment characteristic 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. We then investigate the impact of system parameters, namely, duty cycle, spectral efficiency, frequency chirp, and span length, on the RoI for long-haul DWDM systems.