Routing and wavelength assignment in optical passive star networks with non-uniform traffic load

This paper considers the problem of routing and wavelength assignment (RWA) in optical passive star networks with non-uniform traffic load. The problem can be considered as designing a logical topology over an optical passive star physical topology with a given non-uniform traffic. The approach uses the bipartite graphs and the concept of time and wavelength division multiplexing (TWDM) embedding process to discuss the problem. The non-uniformity of the traffic load makes the logical design computationally hard and requires heuristic algorithms. Then, a linear program can solve the routing. We present an algorithm for effectively assigning a limited number of wavelengths among the access nodes of a WDM multi-hop network, which are connected via a passive star topology. The RWA problem for such a network with non-uniform traffic load is discussed for the first time. The idea is based on reducing the maximum load on each wavelength by using more wavelengths available. The proposed algorithm is tested on several traffic models, and results are given to show the improvement in the performance of the network using our algorithm.