Blocking behavior of crosstalk-free pruned optical banyan networks

Crosstalk-free pruned optical banyan networks on vertical stacking scheme (namely, EP-VSOB networks) has been proposed in the literature for faster connection establishment that can be used in optical cross-connect. The routing algorithm provided with the networks has optimal time complexity, O(log₂N). In that architecture, the number of pruned planes has always been considered as √N (or √2N when log₂N is odd), and a few extra planes (regular banyan) has been added with this pruned planes. The switch architecture has very low blocking probability with considerably lower cost and high speed. In this paper we study the blocking behavior of a generalized architecture of pruned optical banyan networks in which the number of pruned planes can be 2^x, where 0≤x≤log₂N in addition to the variable extra planes. This generalization helps us find the desirable tradeoff between different constraint and performance metrics. Our simulation results show that for some given performance requirements (e.g. cost, speed or blocking probability) we can choose a network that has lower switch count compared to √N -plane pruned crosstalk-free optical banyan networks. For example, to ensure the blocking probability to be less than 0.02, previously we would choose a pruned network of 32 pruned-planes and 1 extra plane (a regular banyan); however, our simulations results show that a network of 16 pruned-planes and 2 extra-planes is enough to ensure the same performance requirement. It is notable that, the hardware cost can be decreased significantly by choosing the alternative combination of pruned and extra planes. We believe our results provide more flexibility in choosing a particular EP-VSOB network satisfying given requirements.