Browsing by Subject "Wavelength Division Multiplexing Networks"

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Open Access
Network design problems in wavelength division multiplexing optical networks
(2001) Erdoğan, Güneş
In this study, we analyze the network design problem arising in Wavelength Division Multiplexing (WDM) networks where tra c is static, wavelength interchanging is allowed and the location and number of the wavelength interchangers are to be determined. Given a topology and tra c data, we try to nd the ber and wavelength interchanger con guration with the minimum cost, that can establish all given connections. We present di erent formulations of the problem and some valid inequalities. Finally, we propose a heuristic method of generating feasible solutions, apply the method on three di erent topologies with varying tra c data, and present the results. The method is based on the idea of partitioning the problem into two; routing problem and wavelength assignment and interchanger location problem. Our results prove to be close to the lower bounds we generate, and indicate that the ber cost performance of the case where all nodes are wavelength interchangers can be attained using a relatively small number of wavelength interchangers.
Open Access
A tabu search algorithm for sparse placement of wavelength converting nodes in optical networks
(2004) Şengezer, Namık
All-optical Wavelength Division Multiplexing networks, providing extremely large bandwidths, are among the most promising solutions for the increasing need for high-speed data transport. In all-optical networks, data is transmitted solely in the optical domain along lightpaths from source to destination without being converted into the electronic form, and each lightpath is restricted to use the same wavelength on all the links along its path. This restriction is known as the wavelength continuity constraint. Optical wavelength conversion can increase the performance and capacity of optical networks by removing this restriction and relaxing the wavelength continuity constraint. However, optical wavelength conversion is a difficult and expensive technology. In this study, we analyze the problem of placing limited number of wavelength converting nodes in a multi- fiber network with static traffic demands. Optimum placement of wavelength converting nodes is an NP-complete problem. We propose a tabu search based heuristic algorithm for this problem. The objective of the algorithm is to achieve the performance of full wavelength conversion in terms of minimizing the total number of fibers used in the network by placing minimum number of wavelength converting nodes. Numerical results comparing the performance of the algorithm with the optimum solutions are presented. The proposed algorithm gives quite satisfactory results, it also has a relatively low computational complexity making it applicable to large scale networks.