Enhancing user fairness in non-orthogonal access with successive interference cancellation for cellular downlink

Aiming at a better tradeoff between the system frequency efficiency measured by the mean user throughput and the user fairness measured by the cell-edge user throughput, we propose applying fractional frequency reuse (FFR) and weighted proportional fair (PF)-based multiuser scheduling to non-orthogonal access with a successive interference canceller (SIC) in the cellular downlink. We also propose a frequency block access policy for cell-interior and cell-edge user groups in FFR, which are appropriate for non-orthogonal access with the SIC. The optimum power is allocated to the non-orthogonally multiplexed users in conjunction with the weighted multiuser PF scheduler. Extensive simulation results show that the proposed non-orthogonal access scheme with the SIC significantly enhances the system frequency efficiency and user fairness at the same time compared to orthogonal access, which is widely used in 3.9 and 4G mobile communication systems.