Not-Aligned Optical Cell Switching Paradigm

Abstract

Most existing all-optical switching paradigms assume that different wavelengths are switched independently, which limits the scalability of core switches. In the optical cell switching (OCS) paradigm, time is divided into time slots of fixed size by time-division multiplexing, and the wavelengths in a time slot are all bundled. Thus, each OCS core switch (OCX) requires a single switching plane and performs mere time–space switching. In OCS, each OCX requires optical slot synchronizers (OSYNs) at all inputs for the arrival slots to be aligned so that cells can be simultaneously forwarded. We propose a new OCS paradigm—not-aligned OCS—where the alignment process takes place inside the OCXs. In not-aligned OCS, no OSYNs are required, and the alignment resources are shared between all input fibers. Therefore, the proposal fulfills diverse objectives: the total number of fiber delay loops and the hardware cost are reduced, and the number of switching operations is also lower than in aligned OCS. Moreover, cell arrival time at the switch is not critical, and the network becomes simpler and more flexible. We also propose a new scheduling algorithm for not-aligned OCS networks. We provide simulation results that show that the not-aligned OCS schema takes the connection blocking probability to reasonable values.