Algorithm for placement of limited wavelength conversion in WDM optical networks

Abstract

ABSTRACT Equipping all nodes of a large optical network with full conversion capability is prohibitively costly. To improve performance at reduced cost, sparse converter placement algorithms are used to select a subset of nodes for full-conversion deployment. Further cost reduction can be obtained by deploying only limited conversion capability in the selected nodes. In this paper, we present a limited wavelength converters placement algorithm based on the k-Minimum Dominating Set (k-MDS) concept. We propose three different cost effective optical switch designs using the technologically feasible non-tunable optical multiplexers. These three switch designs are Flexible Node-Sharing, Strict Node-Sharing and Static Mapping. Compared to the full search heuristic of O(N 3 ) complexity based on ranking nodes by blocking percentages, our algorithm on one hand has a better time complexity O( 2.N ) - is the number of disjoint sets provided by k-MDS ; and on the other hand avoids the local minimum problem. The performance benefit of our algorithm is demonstrated by network simulation with the U.S Long Haul topology having 28 nodes ( is 5). From the optical network management point of view, our results also show that the limited conversion capability can achieve performance very close to that of the full conversion capability; while not only decreasing the optical switch cost but also enhancing its fault tolerance. Keywords: Limited wavelength conversion, All-optical WDM simulation and modeling, Optical Crossconnect Design, Wavelength converter placement, Minimum dominating set.