Performance Analysis on Negligible Blocking DC-based Optical Switching Networks Under Crosstalk Constraint

Banyan networks are attractive for serving as the optical switch architectures due to their nice properties of small depth and absolutely signal loss uniformity. Banyan structure is one of the candidates for serving as the directional-coupler (DC)-based switching systems that can switch signals at the rate of several terabits per second. Despite many advantages, optical banyan networks suffer from an intrinsic crosstalk problem that must be overcome in building a robust switching system. Vertical stacking of multiple copies of an optical banyan network is a novel scheme for building nonblocking optical switching networks. The resulting network, namely vertically stacked optical banyan (VSOB) network, preserves all the properties of the banyan network, but increases the hardware cost significantly under first order crosstalk-free constraint. Blocking behavior analysis is an effective approach to studying network performance and finding a graceful compromise among hardware cost, crosstalk tolerance and blocking probability. Little is known on analyzing the blocking behavior in such VSOB networks with some degree of crosstalk constraint. In this paper, the implementation of constructing negligible blocking VSOB networks under various small degree crosstalk constraints will be presented. We find how crosstalk adds a new dimension to the performance analysis on a VSOB network. We implement the possible upper bound on blocking probability which can describe the overall blocking behavior in VSOB networks. The numerical results implanted in the paper can guide network designer in finding the tradeoff among the blocking probability, the degree of crosstalk and the hardware cost in terms of vertical copies of Banyan network.