Eccentricity of the nodes of OTIS-cube and Enhanced OTIS-cube

In this paper we have classified the nodes of OTIS-cube based on their eccentricities. OTIS (optical transpose interconnection system) is a large scale optoelectronic computer architecture, proposed in [1], that benefit from both optical and electronic technologies. We show that radius and diameter of OTIS-Qn is n + 1 and 2n + 1 respectively. We also show that average eccentricity of OTIS-cube is (3n/2 + 1). In [10], a variant of OTIS-cube, called Enhanced OTIS-cube (E-OTIS-Qn) was proposed. E-OTIS-Qn is regular of degree n + 1 and maximally fault-tolerant. In this paper we have given a classification of the nodes of E-OTIS cube and derived expressions for the eccentricities of the nodes in each class. Based on these results we show that radius and diameter of E-OTIS-Qn is n+ 1 and ⌊4n+ 4/3⌋ respectively. We have also computed the average eccentricity of E-OTIS-Qn for values of n upto 20.