Routing and Wavelength Assignment in Optical Networks Using Boolean Satisfiability

Optical networks consist of switches that are connected using fiber optics links. Each link consists of a set of wavelengths and each wavelength can be used by one or more users to transmit information between two switches. In order to establish a connection between the source and destination nodes, a set of switches and links must be efficiently selected. This is known as the routing problem. A wavelength is then assigned in each selected link to establish the connection. This is known as the wavelength assignment problem. The problem of routing and wavelength assignment (RWA) in optical networks has been shown to be NP-complete. In this paper, we propose a new approach to solving the RWA problem using advanced Boolean satisfiability (SAT) techniques. SAT has been heavily researched in the last few years. Significant advances have been proposed and have lead to the development of powerful SAT solvers that can handle very large problems. SAT solvers use intelligent search algorithms that can traverse the search space and efficiently prune parts that contain no solutions. These solvers have recently been used to solve many challenging problems in Engineering and Computer Science. In this paper, we show how to formulate the RWA problem as a SAT instance and evaluate several advanced SAT techniques in solving the problem. Our approach is verified on various network topologies. The results are promising and indicate that using the proposed approach can improve on previous techniques.