Harmonized multiuser transmission scheme for cellular systems

Besides multiuser multi-input multi-output (MU-MIMO), non-orthogonal multiple access (NOMA) has been proposed as another promising alternative for multiuser multiplexing in cellular systems targetting for efficient spectrum utilization, and consequently has been attracting the attention of an increasing number of universities and institutes in both academic and industrial areas. In this paper, we focus on the azimuthal difference between the paired users, and investigate its influence on the system performance for both MU-MIMO and NOMA, respectively. The investigation reveals the different preference of the both schemes in respect of the inter-user azimuthal difference. Accordingly, a harmonized transmission framework for multiuser multiplexing has been proposed whereby the better transmission scheme of the both is always selected. Theoretical analysis justifies its effectiveness.