Computing Approximate Blocking Probabilities in Wavelength Routed All-Optical Networks with Limited- - INFOCOM '99. Eighteenth Annual Joint Conference of the IEEE Computer and Communications Societies

Absfrcrcf-In this paper, we propose a method to calculate the average blocking probability in all-optical networks using limited-rmge wavelength conversion. Previous works have shown that there is a remarkable improvement in blocking probability while using limited-range wavelength conversion [2], [3] but these analytical models were either for a path [2] or for a mesh-torus network [3]. Using a graph-theoretical approach, we extend Birman’s model [4] for no wavelength conversion and derive an analytical expression to compute the blocking probabilities in networks with limited-range wavelength conversion for fixed routing. The proposed analytical model is a generalization of Birman’s model and is applicable to m y network topology. We consider the case where an incoming wavelength can be converted to d adjacent outgoing wavelengths on either side of the input wavelength, in addition to the input wavelength itself, where d is the degree of conversion. Using this model we demonstrate that the performance improvement obtained by full wavelength conversion over no wavelength conversion can almost he achieved by using limited wavelength conversion with the degree of conversion, d, being only 1 or 2. In a few example networks we considered, for blocking probabilities up to a few percent, the carried traffic with limited conversion degree d = 2 was almost equal to the carried traffic for full wavelength conversion. The results obtained show that significant improvements in blocking performance can be obtained by providing limited-range wavelength conversion of small degree within the network.