Vertically stacked Benes networks for crosstalk-free permutation

Crosstalk in optical switching elements (SEs) is one of the major shortcomings in optical switching networks, and avoiding crosstalk is an important issue for proper optical network operation. We propose a new class of optical multistage interconnection networks (MINs)-vertically stacked Benes networks VSB(N, K) that have N inputs (outputs) and consist of K vertically stacked Benes networks. The VSB(N, K) network can support any permutation of an N-element set {0, 1, ..., N-1}. Complete algorithms to realize crosstalk-free permutation in a VSB(N, K) network are the main contributions of this paper.