Multi-Antenna Non Orthogonal Multiple Access Using Block-Based Spatial Modulation

Multi-antenna non-orthogonal multiple access (NOMA) achieves massive connectivity and large spectral efficiency (SE). The successive interference cancellation (SIC) in NOMA improves the SE of stronger user at the expense of weaker user, and consequently compromises user fairness. We propose a novel block spatial modulation (BSM)-based downlink NOMA wherein information for one user in a group is mapped to the indices of active antenna in a transmission block, while that of the second user is mapped to QAM symbols. The proposed scheme obviates the need of SIC, and therefore has high user fairness. We also show that the proposed BSM-NOMA scheme has lower bit error rate and higher SE than an existing spatially-modulated NOMA scheme.