λ-ADJUST scheduling algorithm for optical switches with reconfiguration delay

Using optical technology brings with it advantages such as scalability, high bandwidth and power consumption for the design of switches/routers. However, reconfigurating the optical fabric of these switches requires significant time under current technology. Conventional slot-by-slot scheduling may severely cripple the performance of these switches due to its frequent request for fabric reconfiguration. A more appropriate way is to use a time slot assignment (TSA) scheduling approach. The switch gathers the incoming traffic periodically and schedules them in batches, while trying to minimize the transmission time. This optical switch scheduling (OSS) problem is defined in this paper and it is NP-complete. Earlier TSA algorithms normally assume the reconfiguration delay to be either zero or infinity for simplicity. To this end, we propose a λ-ADJUST algorithm, which breaks this limitation and self-adjusts with different reconfiguration delay values. The algorithm runs at O(δN²logN) time complexity, guarantees a 100% throughput and a bounded worst case delay. In addition, it outperforms existing TSA algorithms across a large spectrum of reconfiguration values.