A Novel QoS-oriented Packet Scheduling Algorithm for Mixed Services in the Downlink of OFMDA System

Orthogonal frequency division multiplexing access (OFDMA) is a promising candidate access scheme for future wireless communication systems. One of the most important research challenges in OFDMA system is the design of a packet scheduler to support multimedia services. In this paper, we propose a novel QoS-oriented dynamic threshold control (DTC) scheduling algorithm for mixed services (i.e., real-time and non-real-time services). For the purpose of satisfying the different QoS requirements of both types of services, we design a unique scheduling strategy for each type of service. A dynamic threshold is adopted to achieve more efficient allocation of subcarriers. Furthermore, in order to maximize the spectrum efficiency, the subcarrier reallocation scheme is proposed to reallocate the surplus subcarriers among users. Simulation results demonstrate that the proposed DTC algorithm is efficient in terms of QoS guarantee and spectrum efficiency.