Researches on non-orthogonal multiple access in multiple-antenna 5G relaying networks

Non-orthogonal multiple access (NOMA), which is an effective solution to improve spectral efficiency, has been considered as an emerging candidate for the fifth generation (5G) multiple access. In this paper, the authors mainly study a NOMA-based multiple-antenna relaying network over Nakagami-m fading channels. In order to measure the performance of the system, the exact outage probability and the ergodic sum rate of the system are derived and the diversity orders of the users are obtained by analyzing the asymptotic expression for the outage probability. Furthermore, due to the complexity of expression for the ergodic sum rate, the authors derive the upper bound of the ergodic sum rate. Finally, by carrying out a series of experimental simulations, the authors prove the correctness of the above theoretical derivations, and through the comparison of NOMA and orthogonal multiple access (OMA), it is found that NOMA can provide better spectral efficiency and user fairness.