We consider in this paper downlink scheduling for different traffic classes at the MAC layer of wireless systems based\non orthogonal frequency division multiple access (OFDMA), such as the recent 3rd Generation Partnership Project\n(3GPP) long-term evolution (LTE)/LTE-A wireless standard. Our goal is to provide via the scheduling decisions quality\nof service (QoS), but also to guarantee fairness among the different users and traffic classes (including delay-sensitive\nand best-effort traffic). QoS-aware scheduling strategies, such as modified largest weighted delay first (M-LWDF),\nexponential (EXP), exponential proportional fair (EXP-PF), and the log-based scheduling rules, prioritize delay-sensitive\ntraffic by considering rules based on the head-of-line (HoL) packet delay and the tolerated packet loss rate, whereas\nthey serve best-effort traffic by considering the classical proportional fair (PF) rule. These scheduling rules do not\nprevent resource starvation for best-effort traffic. On the other side, if both traffic types are scheduled according to the\nPF rule, then delay-sensitive flows suffer from delay bound violations. In order to fairly distribute the resources among\ndifferent service classes according to their QoS requirements and channel conditions, we employ the concept of fuzzy\nlogic in our scheduling framework. By employing the fuzzy logic concept, we serve all the traffic classes with one\npriority rule. Simulation results show better intra-class and inter-class fairness than state-of-the-art scheduling rules.\nThe proposed scheduling framework enables to appropriately balance delay requirements of traffic, system\nthroughput, and fairness.
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