Single-wavelength optical buffers: non-equidistant structures and preventive drop mechanisms

We present two approaches that aim at reducing the loss rates in an optical buffer having access to a single outgoing channel. As opposed to a conventional electronic buffer, such a system consisting of a number of fibre delay lines (FDLs) can only realize a discrete set of delay values to resolve contention. This leads to voids on the outgoing channel, which increases the losses. Traditionally the FDL lengths are equidistant. Our first approach distinguishes itself by allowing more flexibility on the delay line lengths. Conditions on which improvements can be achieved are discussed. These conditions are obtained by defining several heuristic algorithms. The second approach tries to reduce channel losses by preliminary discards of optical burst that cause large voids. To perform this analysis we make use of a Markov Decision Process. Moreover we present a comparative study between these two approaches and the traditional situation.