Downlink non-orthogonal multiple access system with limited feedback channel

Non-orthogonal multiple access (NOMA) has been recognized as a promising multiple access technology for fifth generation (5G) mobile communication system. However, the advantage of NOMA is only proven under the ideal condition of transmitter knowing the perfect knowledge of channel state information (CSI). In this paper, NOMA downlink multi-user system, in which the transmitter acquires the CSI through the limited feedback channel, is studied. Making use of the imperfect CSI feedback, channel direction information (CDI) and channel quality indicator (CQI), we propose the user selection scheme to reduce the interference between the NOMA users. Furthermore, a power allocation scheme is applied to improve the sum-rate of NOMA system. Numerical results show that NOMA system with limited feedback channel still gains higher system rate than traditional orthogonal multiple access system.