A downlink scheduling based on queue length estimation for VoIP in WiMAX networks

How to allocate resources in an efficient way and the provision of Quality of Services (QoS) guarantee are the major issues in delivering delay sensitive traffic, like VoIP service, in WiMAX (Worldwide Interoperability for Microwave Access). One well-designed scheduling algorithm is expected to coordinate QoS-related functional entities in WiMAX architecture. Existing downlink scheduling algorithms of WiMAX, like DRR (Deficit Round-Robin) and WRR (Weighted Round-Robin), usually reserve minimum rate to each type of traffic and cannot consider the status of queue length of each connection, thus making it unsuitable for VoIP on-off traffic model. Therefore, we propose an efficient downlink scheduling algorithm, which allocate the bandwidth based on queue-length estimation. We compare the proposed scheme with DRR and WRR by estimating the system performance such as average delay, loss rate and throughput under several traffic scenario and system parameters value.