Proposed WiMAX hybrid scheduler with split FTP traffic and its performance evaluation

The most promising broadband wireless access technology, Worldwide interoperability for Microwave Access (WiMAX), is the commercial name of IEEE 802.16. It is popular due to its middle range access mobile, high data rates, high scalability and convenient deployment. WiMAX provides Quality of Service (QoS) to various triple-play services (voice, video and data) through five service classes. QoS provisioning to various service classes in WiMAX is achieved by a scheduler at MAC layer. Selection of appropriate scheduler is based on certain design goals, such as attainment of QoS required for variety of applications, fairness to all services, reduced complexity etc. However, in general, File Transfer Protocol (FTP) traffic starves for bandwidth under the presence of high priority real-time traffic. This paper proposes a WiMAX hybrid scheduler that integrates homogeneous schedulers namely Weighted Fair Queuing (WFQ), strict priority and a Round Robin (RR). The unique feature of the proposed scheduler is that it has a splitter for FTP traffic with varying ratio and two stage priority schedulers for providing proper traffic load distribution for packet scheduling. The analytical modelling of proposed scheduler is achieved by Markov Chain and balance equations are solved to derive performance indicators such as mean queue length of packets, mean queuing delay, throughput and inter-class fairness for various triple-play services. The analytical results show that, as compared to recently reported hybrid WiMAX schedulers, proposed hybrid scheduler fulfils QoS requirements of various services and the splitting of FTP traffic has improved fairness among various services.