Routing and Wavelength Assignment (RWA) is the work of finding a route for a given connection and finding the suitable set of available free wavelengths on that route to complete the connection. Existing research demonstrated that an effective RWA plays an important role in improving the blocking performance of an optical network. Specially, it significantly reduces the blocking probability of an optical network.
For simplicity, RWA is divided into two sub-problems: Routing sub-problem and Wavelength Assignment sub-problem. Routing sub-problem is the task of finding the route for a given connection. Wavelength Assignment is the work that finds the set of free wavelengths in the route has chosen for the connection to be fully performed. There have been many routing as well as wavelength algorithms. In this thesis, we focus on the second Wavelength Assignment sub-problem. In detail, we propose a dynamic heuristic wavelength assignment algorithm, called Longest Segment (LS) algorithm, for WDM networks. Using simulation, we carry out several studies over typical topologies including the 14-node NSFNET and the 8-node ring network. In each topology, we compare the blocking probability of our proposed algorithm with that of other previous algorithms under several existing routing algorithms. The simulation results show that the blocking performance of our algorithm is better than that of the others in the environment of sparse wavelength conversion as well as full wavelength conversion. In addition, using mathematical analysis, we point out that our LS algorithm minimizes the usage of converters which had not achieved previously. Furthermore, the algorithm’ low complexity is another advantage of our algorithm. The simulation results show that our algorithm works appropriately.
