  Non-orthogonal multiple access (NOMA) is widely recognized as a potential
multiple access (MA) technology for efficient spectrum utilization in the
fifth-generation (5G) wireless standard. In this paper, we present the
achievable sum rate analysis of a cooperative relaying system (CRS) using NOMA
with two different receive diversity schemes - selection combining (SC), where
the antenna with highest instantaneous signal-to-noise ratio (SNR) is selected,
and maximal-ratio combining (MRC). We also present the outage probability and
diversity analysis for the CRS-NOMA system. Analytical results confirm that the
CRS-NOMA system outperforms the CRS with conventional orthogonal multiple
access (OMA) by achieving higher spectral efficiency at high transmit SNR and
achieves a full diversity order.
