Integrated fault tolerant connections-scheduling for dilated Benes network

Abstract

The 2×2 electro-optical directional coupler is a common switching element in dilated optical multistage interconnection networks (DOMINs) and can be applied to photonic switching technology. Because of the undesirable coupling within an optical switch, a portion of the energy of the input signal might be transmitted to the undesired output terminal in the switch. A switch is said to be faulty if it causes excessive crosstalk above a given threshold, and optical crosstalk is a problem commonly found in DOMINs. The problem of connections-scheduling with faulty switches in a dilated re-arrangeable photonic network, say dilated Benes network (DBN), is studied and an integrated fault tolerant DBN architecture is proposed. Based on the faulty switch information given from the fault diagnosis algorithm, the fault-free path generation algorithm and scheduling algorithm are devised to schedule a set of connections avoiding faulty switches with a polynomial time complexity in the DBN. It is desirable to keep the number of rounds as small as possible. The simulation results show that the proposed method outperforms the greedy-scheduling algorithm in terms of routing number, number of failed connections, minimum number of rounds, and connection success probability when the size of the network is large. Furthermore, the proposed methodology can be embedded in the optical switching system to achieve self-testing.