Joint NOMA and Beamforming in PNC-coded Parallel Relay Channels

Non-orthogonal multiple access (NOMA) has been a popular choice to deploy multiple access in physical layer network (PNC) coded parallel relay channels. However, when the number of parallel relay channels are large, interference can seriously hinder the NOMA based communication. To have a spectral efficient and reliable communication in parallel relay channels, this paper proposes a joint NOMA and beamforming scheme where the key contribution is the use of beamforming pre-coding to avoid cross interference between individual relay based communications. However, NOMA is also used in selected clusters to provide multiple access which reduces the number of antennas required at the base-station. The proposed communication scheme is tested for throughput and it shows that it achieves a superior throughput than communication schemes operating PNC coded parallel relay channels with NOMA only.