Improved Cognitive Radio with Cooperative Non-Orthogonal Multiple Access

Abstract

Non-orthogonal multiple access (NOMA) and cognitive radio (CR) are two different techniques employed to produce highly spectral efficient multi-user communications. This research investigates the possibility of exploiting NOMA to carry out cognitive secondary user (SU) communication even when the primary user (PU) is active, hence increasing the overall system throughput. More specifically, it proposes a cooperative downlink communication scheme when the PU is much closer to the transmitter than the SU, which is a situation that had not been investigated before.