QoS Guaranteed Batch Scheduling for Optical Switches Based on Unequal Weight Sequence

Abstract

Due to the reconfiguration overhead of optical fabrics, batch scheduling method is generally used to schedule an optical packet switch, with a necessary speedup inside the switch to ensure 100% throughput with a bounded packet delay. Existing algorithms take each traffic matrix as a batch, and adopt traffic matrix decomposition techniques to decompose it into the sum of a set of weighted permutation matrices (which are then used as switch configurations). Nevertheless, existing algorithms adopt an equal weight for all switch configurations, meaning that each configuration should be held for the same time duration to transmit packets. We observe that this rigid strategy may limit the flexibility of the scheduling and result in a large speedup requirement due to inefficient time slot utilization. Motivated by this observation, we propose a UWS (Unequal Weight Sequence) algorithm to decompose the traffic matrix. UWS uses a different weight for each switch configuration. It first takes an arithmetic progression as the starting weight sequence, and then adjusts the weights for configurations to ensure 100% throughput with a bounded packet delay (such that QoS can be guaranteed). We theoretically prove that the worst case speedup of UWS will never be larger than that of the best existing ADAPT algorithm. Simulation results indeed demonstrate a speedup improvement of around 15%.