Performance Analysis of DF-Relaying-based Cooperative NOMA System with Partial Relay Selection

Non-orthogonal multiple access (NOMA) is a key technique for 5G and beyond wireless communications, as its spectral efficiency is better than conventional orthogonal multiple access (OMA) techniques. In this paper, a cooperative NOMA system model with partial relay selection (PRS) scheme is proposed, where the base station (BS) sends the message signal to the mobile users with the help of multiple decode-and-forward (DF) relays. Here, the selection combining technique is employed by mobile users to combine the direct and relay transmissions for improving the reliability. In addition, we also investigate the performance of the proposed system model as well as impact of the number of relays on the system performance through outage probability, ergodic capacity, and overall system throughput considering the Rayleigh fading channel. Further, the obtained expressions for the performance metrics are validated using Monte-Carlo simulation results.