Impairment aware routing and wavelength assignment algorithms for optical WDM networks and experimental validation of impairment aware automatic light-path switching

Physical Layer Impairments (PLIs) degrade the transmitted signal strength and Quality of Transmission (QoT) in optical WDM networks. Accumulation of PLIs is increased with long reached optical transparent links, supported data rate and power economy. In the present paper we have designed and implemented dynamic Impairment-Aware Routing and Wavelength Assignment (IA-RWA) heuristic algorithms which introduce impairment awareness in optical transparent links without deploying any additional regenerators. The first IA-RWA solution monitors the effects of PLIs through Distributed Light–path Monitoring modules to obtain certain QoTs. The second IA-RWA algorithm demonstrates substantial reduction in the effects of non-linear PLIs with the implementation of dynamic channel spacing (DCS). In the third IA-RWA solution, instead of dropping the complete light-path we use the available curtailed bandwidth of the impaired light-path to enhance the utilization of the optical capacity and reduce the blocking probability. We also provide the experimental implementation of impairment aware automatic switching of the light-paths.