Performance Evaluation of Non-Orthogonal Multiple Access Combined with Opportunistic Beamforming

Non-orthogonal multiple access (NOMA) utilizing power domain and advanced receiver is a promising technique for future radio access. Multi-antenna techniques have been deeply studied during the past decade to boost system performance by virtue of spatial multiplexing and/or spatial diversity. It is of great interest to study how to efficiently and effectively combine the two techniques together for further system performance improvement. This paper investigates on the combination of NOMA with opportunistic beamforming (OBF), which has been proposed as a practical multi-antenna transmission scheme with good performance and very limited feedback. The key design issues of NOMA with OBF are investigated including precoding, transmission power assignment, user feedback and scheduling. Furthermore, a method to improve the system performance with OBF is proposed by utilizing historical information. The performance of NOMA with OBF is investigated by system-level simulations with very practical assumptions and parameters in order to provide insights into the suitability of combining OBF with NOMA for future radio access. Simulation results show the proposed method is effective and NOMA with OBF is a promising scheme for future wireless communication systems.