Enhanced CSI feedback scheme for non-orthogonal multiple access

Non-orthogonal multiple access (NOMA) has been proposed as a promising technology in cellular systems 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. However, its performance largely depends on the azimuthal difference between the paired users. Targetting for better performance, it is proposed in this paper to make a base station (BS) understand the azimuthal difference between each pair of its users. Moreover, an enhanced channel state information (CSI) reporting mechanism for NOMA transmission has been proposed whereby more beneficial user pairing and consequently enhanced performance can be achieved. Theoretical analysis justifies its effectiveness.