Supporting Quality-of-Service Scheduling in a TT-FR WDM System

In this paper, our recent work interval-based orderly scheduling strategy (IOSS) is extended by adding quality-of-service (QoS) provisioning. A revised medium access control (MAC) protocol is introduced, which supports priority-based QoS in wavelength division multiplexing (WDM) networks with star topology. The proposed interval-based prioritized orderly scheduling strategy (IPOSS) operates in a distributed manner, and has the capability of handling channel collision and destinations conflicts in order to provide a collision-free scheduling scheme. Each node in the network is equipped with a tunable transmitter and a fixed receiver, assuring that the scheme is scalable with respect to the number of nodes and channels. Also, each node may accept high- and low-priority packet arrivals. IPOSS favors high-priority packets, without regarding packets´ length or packets´ destination. Moreover, the proposed scheme differentiates the packet´s schedule order by prioritizing the long-length over the short-length packets. It is found that the adopted access control scheme achieves a critically high throughput-delay performance for real-time traffic. Furthermore, IPOSS presents a little bit improved throughput performance than IOSS scheme, since it handles in a different way the case in which two or more requests demand the same amount of transmission time. The traffic involved in the simulation results follows Bernoulli and Poisson distribution, regarding the arrival of the requests.