Research On Algorithms For Routing And Wavelength Assignment In WDM Optical Networks

With the development of information society and the explosive growth of internet. Information is more and more important to us, which is promoting the construction of broadband backbone network. Wavelength Division Multiplexing (WDM) is an approach which can use the enormous bandwidth of the optical fiber. One fiber can be employed for multiple data streams. Simultaneously, It is easy to expend can fully utilize fiber optical capacities. The wavelength-routed optical network (WRON) based on the WDM and wavelength routing techniques is one of the most promising solutions for the realization of optical network.Because the number of the wavelengths which are multiplexed in a single fiber is limited, without wavelength conversion, all the communication of the route must use the same wavelength, namely wavelength continuity limited. RWA is an important problem in WDM networks. It is accomplished by selecting a route between the two end nodes and assigning a suitable wavelength. The routing and wavelength assignment algorithm is an optimization algorithm when the network resources are restricted in WORN. For the sake of proper network design and effective usage of network resource, it is crucial to study the routing and wavelength assignment algorithms. In order to make full use of the limited resource and provide communication capability as large as possible. In the case of resource-constrained network routing and wavelength assignment algorithm is a superior optimization algorithm for network optimization of reasonable design, efficient use of network resources have a very important significance.In this paper, WDM optical networks in the RWA algorithm is studied in detail, the principal tasks include:Firstly, this paper introduced the course of development of optical fiber communication, optical networking concepts, as well as WDM technology. WDM optical networks highlighted the key technologies, important components and network hierarchical institution.Secondly, this paper described the concept of RWA algorithm and its research significance. For WDM optical networks in the RWA problem in-depth study of the problem is given a mathematical model of RWA. Connection request according to the different type of business will be divided into a static RWA (SRWA) problem and dynamic RWA (DRWA) problem were studied on a typical algorithm has been compared and analyzed, then this paper proposes a new static RWA algorithm, it is based on graph coloring method. The experimental result shows that the algorithm can well improve the network wavelength utilization and improve the overall network performance.Finally, Taking into account the information in the network are generally not as simple as a single best-effort delivery, different connection requests may have different business levels, different business levels have different requirements of blocking probability. The client is needed distinguish the different priorities. In the case of wavelength conversion and consider the channel-priority cases, this paper improve the relative minimal impact algorithm which has been on a better blocking performance. And compare the algorithm, the result of simulator shows the proposed algorithm has better performance and reduces the network blocking probability, In addition, this paper proposes a new network wavelength assignment algorithm for the fairness issues of network, it takes into account both the priority of the network and also takes into account the fairness of the network. Through the simulation of two different networks topology, the final results show that the new algorithm can appropriately increase the blocking rate of short-distance optical path connection request and effectively reduce the blocking rate of the long-distance optical path connection request, thus improves the fairness of network.