An efficient scheduling for diverse QoS requirements in WiMAX

Abstract

WiMAX is one of the most important broadband wireless technologies and is anticipated to be a viable alternative to traditional wired broadband techniques due to its cost efficiency. Being an emerging technology, WiMAX supports multimedia applications such as voice over IP (VoIP), voice conference and online gaming. It is necessary to provide Quality of Service (QoS) guaranteed with different characteristics, quite challenging, however, for Broadband Wireless Access (BWA) networks. Therefore, an effective scheduling is critical for the WiMAX system. Many traffic scheduling algorithms are available for wireless networks, e.g. Round Robin, Proportional Fairness (PF) scheme and Integrated Cross-layer scheme (ICL). Among these conventional schemes, some cannot differentiate services, while some can fulfill the service differentiation with a high-complexity implementation.

This thesis proposes a novel scheduling algorithm for Orthogonal Frequency Division Multiplex/Time Division Multiple Access (OFDM/TDMA)-based systems, which extends the PF scheme to multiple service types with diverse QoS requirements. The design objective is to provide differentiated services according to their QoS requirements, while the objective can be achieved by adjusting only one unique parameter, the time window for evaluating the average throughput. By extensive simulation, it is shown that the proposed scheduling algorithm exploits the advantage of the PF scheme, enhancing the throughput, and distinguishes the services in terms of the average delay. Afterward, we prove the superiority of the new scheme over the conventional ones by showing simulation results.