AbstractIn this paper, an uplink scheme that exploits cooperative diversity using power domain nonorthogonal multiple access (NOMA), termed UCD‐NOMA, with successive interference cancelation receivers is proposed. A two‐user case is considered, where both the NOMA users can communicate with the base station directly and indirectly via a half‐duplex decode‐and‐forward relay. Under perfect and imperfect successive interference cancelation assumptions, the ergodic sum capacity, outage probability, and outage sum capacity of the considered protocol are analyzed over the Rayleigh fading channel. As a protocol with which to compare the proposed UCD‐NOMA protocol, an uplink cooperative network using a conventional multiple access technique (termed UCD‐OMA) is also considered and analyzed. The performance excellence of UCD‐NOMA as compared to UCD‐OMA is clarified through simulations and theoretical analyses.