Performance Comparison of Different Wimax Configurations: Impact of Scheduling and Contention Resolution on Quality of Service in Wimax Networks

WiMAX (Worldwide Interoperability for Microwave Access) is a wireless access technology based on the IEEE 802.16 standard. The scope of WiMAX is to provide last mile wireless broadband access for fixed and mobile users as an alternative to the wireline DSL and cable access. The MAC protocol supports four service classes, the unsolicited grant service (UGS) for constant bit rate services, the real-time polling service, the non real-time polling service, and the best-effort service. The focus of this study is to simulate the performance of VoIP and FTP traffic when transmitted over UGS or best-effort connections. The WiMAX MAC Layer and a simplified PHY Layer model are implemented in the OPNET Modeler. Furthermore, a novel scheduling scheme is developed and different methods for requesting bandwidth for the uplink best-effort connections are investigated. Besides, the focus is laid on the algorithm which is used for contention resolution. In addition, the impact of the frame duration, the number of transmission opportunities per frame, and the kind of bandwidth requests on the total system performance is simulated.