A crosstalk free routing algorithm of optical Multistage Interconnection Networks

Crosstalk is an intrinsic drawback of optical networks and avoiding crosstalk is important for making fruitful application of optical switching networks. Rearrangeable optical Multistage Interconnection Networks (MINs) are feasible since they have lower complexity than their strictly counterparts. In this paper, we propose a crosstalk free routing algorithm of optical MINs and we apply it to three examples of optical MINs, the Generalized Recursive Network (GRN), the Banyan Network and the Benes Network. The routing algorithm is derived based on the idea of the semi-permutation and it completes the decomposition of a permutation.

I. Introduction

Communications among processors in a parallel computting system are always the main design issue when a parallel system is built or a parallel algorithm is designed. Fiber optic communications offer a combination of high bandwidth, low error probability, and gigabit transmission capacity. Multistage interconnection networks have an important interconnecting scheme for parallel computing systems [1]. Two major problems in designing optical switch networks are signal loss and crosstalk. There are two ways in which optical paths can interact in planar switching networks. First, two optical channels on different waveguides may cross each other in order to obtain a particular topology. This is called channel crosstalk. Alternatively, two paths sharing a switching element will experience some undesired coupling from one path to the other. This is called optical crosstalk [3]. Therefore, the main objective of this paper is to propose a crosstalk free routing algorithm of the optical MINs and apply the algorithm on three optical MINs as examples.