Routing algorithms with adaptive weight function based on total wavelengths and expected available wavelengths in optical WDM networks

This paper studies routing and wavelength assignment in wavelength-routed (WR) optical WDM networks which are circuit-switched in nature. When a session request is given, the hard task of routing and wavelength assignment (RWA) is to calculate the satisfiable path between two nodes, and also to assign an available set of wavelengths along this path. Therefore, we have proposed a new routing and wavelength assignment algorithm, called total wavelengths and expected available wavelengths (TEW) algorithm in order to achieve the effective routing and wavelength assignment that can guarantee the service for user´s requirement. The link weight function is considered as the main factor for route selection in TEW algorithm. This function is calculated by using a determination factor of the number of wavelengths that are being used currently and are supposed to be available after a certain time. The session requests from users are routed on the links that has the least number of link weights by using Dijkstra´s shortest path algorithm. This means that the selected lightpath have the minimum utilization and maximum expected available wavelengths. The impact of proposed link weight computing function on the blocking probability is investigated by means of computer simulation and comparing with the traditional mechanism. The results show that the proposed TEW algorithm can achieve better performance in terms of the blocking probability