Impairment-aware dynamic routing and wavelength assignment in translucent optical WDM networks

Abstract

Imperfections in the optical fiber and other optical phenomena give rise to several physical layer impairments that degrade the Quality of Transmission (QOT) of a propagating optical signal in WDM networks. 3R regenerators are deployed to restore the QOT of the optical signal before it falls below a predetermined threshold value. In opaque networks, these regenerators are installed in all the nodes. However as the size of the network increases, several practical issues related to regenerators such as installation costs, power consumption, physical space requirements, upgradability, operation and maintenance costs etc. have to be considered. In view of these practical constraints, the trend has been to move towards the low cost translucent networks, in which the 3R regenerators are sparsely yet strategically placed in the network. We propose a new approach to solve the Impairment-Aware Routing and Wavelength Assignment (IA-RWA) problem under dynamic network traffic conditions, assuming a given sparse placement of the regeneration capable nodes. Since 3R regenerators use Optical-to-Electrical-to-Optical (OEO) conversion to restore the optical signal quality, which is an expensive operation, the objective of our IA-RWA approach is to find a solution that involves the fewest possible number of regenerators. Our approach is based on the A* (Best First Search) algorithm and guarantees an optimal solution (if it exists). © 2014 Springer-Verlag.