Improving the energy efficiency of scheduling algorithms for OPS/OBS buffers

With ever-increasing demands for bandwidth, optical packet/burst switching is used to utilize more of the available capacity of optical networks. In existing prototypes of optical switches, packet contention is resolved by combining time and wavelength multiplexing by means of fiber delay lines and wavelength converters. Although optical switches dissipate less energy than their electronic counterparts, their consumption remains substantial. Since wavelength converters contribute significantly to the switches overall energy consumption, they should be powered only when needed. Existing scheduling algorithms, however, do not take the usage of wavelength converters (and the related energy consumption) into account. To this end, we developed and evaluated new cost-based scheduling algorithms, which take both gap and delay into account to schedule an incoming packet. The performance improvement of these algorithms over existing algorithms can be traded off for a significant reduction in up-time of the wavelength converters by introducing a conversion cost in the involved cost function. This is backed by Monte Carlo simulation results, in which the algorithms are applied both in a void-filling and non-void-filling setting. The algorithms are of the same implementation complexity as existing algorithms, and thus of immediate value to switch designers