Distributed Spatial Modulation Aided NOMA

In this paper, a novel cooperative diversity protocol based on the association of non-orthogonal multiple access (NOMA) and distributed spatial modulation (DSM) is introduced. In the proposed protocol, two source symbols are multiplexed in the power domain, while one source symbol obtains a diversity gain due to its being relayed according to the DSM principle; this doubles the data rate for the source-to-destination link as compared with conventional DSM. We propose two demodulators for use at the destination: an error-aware demodulator which is robust to demodulation errors at the relays, and a suboptimal demodulator which assumes error-free demodulation at the relays. Simulation results demonstrate that while the proposed protocol achieves a source data throughput equal to that of a full-duplex system, its BER performance also significantly outperforms the full-duplex relaying benchmarks of successive relaying and virtual full-duplex DSM.