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The WiMAX technology has been defined to provide high throughput over long distance communications and support the quality of service (QoS) control applied on different applications. This paper studies the fairness time-slot allocation and scheduling problem for enhancing throughput and guaranteeing QoS in multihop WiMAX mesh networks. For allocating time slots to multiple subscribe stations (SSs), fairness is a key concern. The notion of max-min fairness is applied as our metric to define the QoS-based max-min fair scheduling problem for maximizing the minimum satisfaction ratio of each SS. We formulate an integer linear programming (ILP) model to provide an optimal solution on small-scale networks. For large-scale networks, several heuristic algorithms are proposed for better running time and scalability. The performance of heuristic algorithms is compared with previous methods in the literatures. Experimental results show that the proposed algorithms are better in terms of QoS satisfaction ratio and throughput.

This paper considers the problem of video stream multicasting over worldwide interoperability for microwave access (WiMAX) networks. Since the MAC layer of a WiMAX network is connection-oriented, each subscriber must be allocated bandwidth from base stations before establishing a connection. However, bad connection quality may decrease the network efficiency. While a base station allocates subchannels to subscribers, variations in channel fading often affect the transmission rate. This paper proposes several transmission scheduling schemes to avoid the effects of channel diversity and improve transmission performance. Our strategy is to divide subscribers into several groups depending on the signal-to-noise rate (SNR) of allocatable channel(s). The objective of this study is to find an optimal schedule to minimize the transmission latency of video streaming and maximize base station capacity. Simulations show that the proposed methods FF and RFF yield efficient multicast scheduling and outperform previous methods.