Scheduling algorithms in optical packet switches with input wavelength conversion

The objective of this study is to propose a new Optical Packet Switching architecture in which the wavelength converters, needed to solve output packet contentions, are shared per input line; according to this sharing strategy the packets arriving at a given input fiber shares a converter pool that can be accessed when wavelength conversions are required. In the paper, we propose analytical and simulation models able to evaluate the performances of the proposed architecture when control algorithms with different complexity, are adopted. Under a unicast traffic scenario, the obtained performances are compared to the ones of the architecture in which the wavelength converters are shared per output line. The carried out comparison shows that, with respect to the architecture with wavelength converters shared per output line, the proposed architecture allows for a 30% saving of wavelength converters when a simple control algorithm is adopted; the saving can reach 50% if an optimized control algorithm is used. In the paper, we also define a heuristic algorithm able to reach in low computation cost, performance near to the one of the optimum algorithm.