A Comparative Study on the Routing and Wavelength Assignment in WDM

Blocking probability is a measure of efficiency in optical networks which is a result of routing and wavelength assignment (RWA) problem. There are several standard algorithms in use like the Dijkstra's algorithm to solve the routing problem. The wavelength assignment algorithms which are standardized are First fit and Random Fit. The objective of this work is to analyze the variation of the blocking probability with respect to variation of load and number of channels and to improve resource utilization while keeping the blocking probability as low as possible. Even after the use of standard wavelength assignment algorithms the blocking probability is still high and there is scope to reduce it. To solve the wavelength assignment problem a new algorithm is proposed which is named as Last Fit. The proposed algorithm Last fit finds the last free channel and then assigns it to the incoming call. The proposed algorithm (last fit) is compared with both standard algorithms i.e. First fit and Random fit and comparative results are tabulated.