On Crosstalk-free Bpc Permutations Routing in an Optical Variable-stage Shuffle-exchange Network

The paper introduces an approach for crosstalk-free bitpermute-complement (BPC) permutations routing in hybrid optical variable-stage shuffle-exchange networks (SENs) of size where N=2, and the number of stages can vary in . The number of stages should be asserted as required by a given BPC permutation for its admissibility. The crosstalk is caused by interacting of two optical signals within the same switch, it can be avoided by decomposing a given permutation to partial permutations which exclude such coupling. In an ideal case the partial permutations should be two semi-permutations with each realizable for one pass through the network. The proposed O(NlogN) algorithm provides an optimal solution for m-stage optical SEN with in the range, but for produced semi-permutations might require further decomposing. It depends on the construction of transition matrix, which can be different for the same BPC permutation. Some guidelines for this case are given.