Design and simulation of a hierarchical priority fairness scheduler in an uplink Worldwide Interoperability for Microwave Access system

The IEEE 802.16 specification supports guarantees about quality of service (QoS) for transmitted packets, but does not describe a scheduling algorithm that can achieve them. This paper presents a packet scheduling scheme that both guarantees QoS as required, and ensures fairness among the subscriber stations. Our scheme uses a novel hierarchical scheduling algorithm for the uplink of a Worldwide Interoperability for Microwave Access (WiMAX) system. We first schedule the real-time service according to the QoS requirement. This meets maximum delay and packet loss requirements of a subscriber station in WiMAX communication networks. In addition to satisfying the QoS requirements, we modify and extend the Proportional Fairness scheduling algorithm to what we call the Subscriber Stations Based Proportional Fairness algorithm, which allocates remaining bandwidth fairly amongst subscriber stations. The algorithm has been implemented and evaluated in a WiMAX simulation platform developed in OPNET. From the simulation results, we can see not only the QoS requirement is satisfied, but also it is fair to all subscriber stations in the WiMAX network.