A novel impairment aware routing and wavelength assignment algorithm for optical WDM networks

In Optical Wavelength Division Multiplex (WDM) networks, besides other factors, the linear and non linear impairments in a lightpath also depend upon wavelength channel assigned to the lightpath along with the state of other channels in the applied WDM spectrum. In this paper we have purposed a novel mixed integer linear programming(MILP) model for solving routing and wavelength assignment problem that employed Binary logic operators to include impairments caused by the state of the neighboring channels. Further, the optical impairment applicable at each wavelength channel was distinct and under given conditions, each provisioned channel experienced variable amount of deterioration. We compared it with existing mathematical models in which strategic spectrum spacing was employed to mitigate the effect of impairments. It has been found that in the former method, Quality of Transmission (QoT) was maintained at all cost. The latter method though converged much faster but due to non-utilization of certain wavelength channels the overall traffic carrying capacity of WDM system get reduced.