A Flexible Wavelength Converter Placement Scheme for Guaranteed Wavelength Usage

Wavelength is one of the most important resources in Wavelength Division Multiplexing(WDM) networks. In optical routing, we are given a set of communication paths (or ligthpaths) in a WDM network and we must assign a wavelength to each path so that paths sharing a link must be assigned with different wavelengths. By properly choosing a set of nodes that are equipped with wavelength converters, the number of wavelengths which is required to support all lights paths can be reduced. In this paper, we study the problem of placing the minimum number of wavelength converters in a network to ensure that the number of wavelengths needed will not exceed a given bound αL, where L is the maximum link load in the network and α is a parameter defined by the network designer to reflect the overall availability of wavelength resources. This problem, however, is proved to be NP-hard. Hence we develop an efficient heuristic algorithm for the problem and extensive theoretical analysis and experimental studies are carried out to verify the effectiveness and performance of the algorithm.