A Balanced Resource Scheduling Scheme With Adaptive Priority Thresholds for OFDMA Downlink Systems

Abstract

This paper proposes a new balanced resource scheduling (BRS) scheme with adaptive priority thresholds for orthogonal frequency-division multiple-access (OFDMA) downlink systems. The BRS scheme achieves an excellent balance between quality-of-service (QoS) requirement guarantee and system throughput enhancement, whereas conventional schemes cannot explicitly and accurately control this tradeoff. Based on the adaptive priority threshold of each user, the BRS scheme first performs a priority-based resource allocation (RA) algorithm for users whose priority value is larger than its priority threshold to fulfill the QoS requirement. The BRS scheme then performs a channel-state-information (CSI)-based RA algorithm for the remaining users to enhance system throughput. To achieve balance between QoS guarantee and throughput enhancement, a fuzzy inference priority threshold generator adaptively and intelligently adjusts the priority threshold of each user. Simulation results show that the proposed BRS scheme with adaptive priority threshold enhances the system throughput by 16%, 8.5%, 8.2%, and 46.8% at traffic load of 0.93, compared with conventional adaptive radio RA (RRA), utility-based RRA, utility-based throughput maximization and complexity reduction scheduling, and fairness and QoS guarantee scheduling with fuzzy controls schemes, respectively, under a QoS requirement guarantee. This approach also outperforms the BRS scheme with fixed priority thresholds in both throughput enhancement and QoS guarantee.