Joint Relay-and-Antenna Selection in Relay-Based MIMO-NOMA Networks

Non-orthogonal multiple access (NOMA) and multiple input multiple output (MIMO) have been widely regarded as two key techniques envisioned for 5G network. In this paper, we apply the core principle of antenna selection (AS) to multi-relay cooperative network, and propose a mechanism that has merits of both MIMO and NOMA. Then, in view of performance and complexity tradeoffs, a suboptimal joint selection scheme with reduced complexity is further presented. Furthermore, to characterize the achievable rates of proposed scheme, the lower and upper bounds of ergodic sum rate at high SNR are derived in closed form. The analytical results are valid for the evaluations for various antenna and relay configurations. Finally, through comprehensive simulations and comparisons, we demonstrate that the proposed scheme can outperform the conventional MIMO scheme or other relevant NOMA schemes in terms of ergodic sum rate and outage performance.