Investigations on Power Allocation among Beams in Non-Orthogonal Access with Random Beamforming and Intra-Beam SIC for Cellular MIMO Downlink

We propose an enhancement to the power allocation among multiple beams in our previously reported non-orthogonal access with random beamforming and intra-beam successive interference canceller (SIC) for cellular multiple-input multiple-output (MIMO) downlink. By equally allocating transmission power among multiple beams, the average user throughput within a cell can be enhanced due to the effective use of spatial multiplexing. The throughput of users at the cell edge may be improved by allocating non-equal transmission power among beams since the inter-beam interference is decreased and the received signal power is increased from the viewpoint of the main beam to which most of the transmission power is allocated. Aiming at further enhancement of the system efficiency and cell-edge user experience in our previous non-orthogonal access scheme, we propose coordinated frequency block-dependent inter-beam power allocation and inter-frequency block power allocation based on fractional frequency reuse (FFR) for inter-cell interference coordination. Based on simulation results, we show that the proposed power allocation method effectively enhances the tradeoff between the average and cell-edge user throughput.