Constraint-aware Routing And Wavelength Assignment Algorithms In Dynamic Optical Networks

IP (Internet Protocol) over optical brings about new challenges to the optical communication network. Consequently, there comes the conception of intelligent optical network. One of the key problems in intelligent optical networks is routing and wavelength assignment (RWA ).The major task of RWA is to find a proper optical route and to distribute wavelength for it reasonably, making the best use of limited resources in order to provide the biggest possible communication capacity. The solving of RWA problems in dynamic optical networks is different from that of in common networks. The former will be constrained by base physical performances, including the wavelength consistency condition, crossing nodes limited, and the restriction of nonlinear quantities. Under the precondition of no wavelength converters in optical networks, this paper proposes a constraint-oriented RWA solving algorithm which fulfills the requirements of wavelength consistency, the restriction of crossing nodes, and the constraint resulted from four-wave mixing (FWM) effects.In order to eliminate the constraint of wavelength consistency, this paper proposes a layered-graph model, applying the idea of distributing wavelength before routing. For the purpose of removing crossing nodes limitations, this paper extends the common-used adjacency list storage contracture, which can then reveal the information of nodes port completely. This paper obliterates the wavelength link vulnerable to FWM effects on the wavelength relation diagram to get rid of the constraint of FWM effects.By the simulation comparisons with several typical RWA algorithms, the method proposed on this paper achieves performance improvement by 80% on blocking probability than the typical RWA algorithms which depend on D (Dijkstra) algorithm to find routes and utilizing the first-hit wavelength to distribute wavelengths. The method proposed on this paper also achieves performance improvement by 5% on blocking probability than the typical RWA algorithm which distributes wavelengths before routing by D(Dijkstra) algorithm. Consequently, the prime characteristic of the method with regard to there constrain conditions proposed on this paper is the ability to find a feasible route. The feasibility referred here means fulfilling the requirements of wavelength consistency, the restriction of crossing nodes, and the constraint resulted from four-wave mixing effects.