Low Complexity BF scheme for downlink MISO‐NOMA systems

Abstract

In this study, the authors investigate the user selection (US), beamforming (BF) and power allocation (PA) problems for the downlink multiple-input–single-output-based non-orthogonal multiple-access system. For the US problem, they matched the BF and PA schemes with different US schemes to achieve the best spectral efficiency performance. For the BF and PA problems, they derive a non-normalised BF scheme to accomplish the BF and PA problems jointly. The non-normalised BF scheme requires much lower computational complexity than the duality BF scheme. According to their simulation results, the non-normalised BF scheme can achieve the same or better spectral efficiency performance than the duality BF scheme. When the number of users sharing the same time–frequency resource is large, both the duality BF scheme and the singular value decomposition (SVD)-based BF scheme cannot obtain spectral efficiency advantage over the OMA scheme. However, the non-normalised BF scheme can maintain the advantage over the OMA scheme.