An Improved Proportional Fair Scheduling in Downlink Non-Orthogonal Multiple Access System

For the next-generation mobile communication system, enlarging the system capacity by allowing the use of non-orthogonal user multiplexing has been suggested. In a downlink multicarrier non-orthogonal multiple access (NOMA) system, single or multiple users are allocated to each subband. In NOMA scheduling, a proportional fair (PF) algorithm, where users with few allocated resources are selected on a priority basis, is generally used. However, to reduce the calculation complexity, only the fairness up to the previous transmitted frames is taken into account. Therefore, to improve the performance, we propose an improved downlink NOMA scheduling scheme that takes the fairness of the target frame into consideration, and orders the allocation subband based on the instantaneous fairness. Through this scheme, a user having little resource allocation may be assigned a good subband. Numerical results show an improved performance in the average user throughput and fairness.