NOMA-Based Transmission in Half-Duplex Two-Way Relay Network

In this paper, by employing the power-domain nonorthogonal multiple-access (NOMA) technique, a transmission scheme is proposed for the two-way relay network (TWRN) that achieves high data rate. In the proposed scheme, which is referred to as NOMA-TWRN, each transceiver sends two symbols simultaneously with different power levels. The symbols with high power are transmitted through the direct link and the low-power symbols are exchanged via the relay node by using a symbol-based network coding operation. We analyze the performance of this scheme in terms of the achievable rate and the outage probability. For comparison, we also analyze the case that instead of the NOMA technique, the orthogonal multiple-access (OMA) is utilized by the transceivers. The simulation results show that when the relay node is closer to one of the transceivers, the NOMA-TWRN outperforms its OMA-based counterpart in terms of the outage probability in the high-rate regime.