Performance of non-orthogonal access with SIC in cellular downlink using proportional fair-based resource allocation

This paper investigates the system-level throughput of non-orthogonal access with a successive interference canceller (SIC) in the cellular downlink assuming proportional fair (PF)-based radio resource (bandwidth and transmission power) allocation. The purpose of this study is to examine the possibility of applying non-orthogonal access with a SIC to the systems beyond the 4G (thus IMT-Advanced) cellular system. Both the total and cell-edge average user throughput are important in a real system. PF-based scheduling is known to achieve a good tradeoff by maximizing the product of the average user throughput among users within a cell. In non-orthogonal access with a SIC, the scheduler allocates the same frequency to multiple users, which necessitates multiuser scheduling. To achieve a better tradeoff between the total and cell-edge average user throughput, we propose and compare three power allocation strategies among users, which are jointly implemented with multiuser scheduling. Extensive simulation results show that non-orthogonal access with a SIC with a moderate number of non-orthogonally multiplexed users significantly enhances the system-level throughput performance compared to orthogonal access, which is widely used in 3.9 and 4G mobile communication systems.