Packet rescheduling in WDM star networks with real-time service differentiation

In this paper, we propose a novel scheduling scheme, namely priority-differentiated scheduling (PDS), which is designed to handle real-time (high-priority) packets in wavelength division multiplexing (WDM) star networks. PDS allows high-priority packets to preempt the prescheduled low-priority (nonreal time) packets. By scheduling the high-priority packets first, and then having the preempted packets rescheduled, PDS guarantees that the high-priority packets can always achieve the earlier transmission than the others in order to meet the quality of service (QoS) requirements. In addition, it does not sacrifice the performance of nonreal-time packets. As a matter of fact, low-priority packets can also benefit from PDS algorithms. This scheme has the capability of handling channel collision and destination conflict, and it supports variable-length packets. This paper also provides an insight into the data channel selection technique along with PDS. With the proposed algorithm that selects a data channel with minimum scheduling latency (MSL), the channel throughput is improved. The performance of the PDS scheme has been extensively studied by means of numerical simulations