MISO NOMA downlink beamforming optimization with per-antenna power constraints

• Published in: Signal processing Vol. 179; p. 107828
• Main Authors: Huang, Yongwei, Zhou, Longtao
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2021
• Subjects: Downlink beamforming; Non-orthogonal multiple access; Per-antenna power constraint; SOCP based approximate algorithm; Downlink beamforming; Per-antenna power constraint; Non-orthogonal multiple access; SOCP based approximate algorithm
• ISSN: 0165-1684; 1872-7557
• DOI: 10.1016/j.sigpro.2020.107828

Consider a multiuser downlink beamforming optimization problem for the non-orthogonal multiple access (NOMA) transmission in a multiple-input single-output (MISO) system with a general number of users. The total transmission power minimization problem is formulated subject to both quality-of-service (QoS) constraints under the NOMA principal and per-antenna power constraints, which are more realistic since each antenna has its own power amplifier and is limited individually by the linearity of the power amplifier. The problem is a nonconvex quadratically constrained quadratic program, and the conventional semidefinite program (SDP) relaxation is not tight. In order to tackle the non-convex problem, we construct second-order cone program (SOCP) approximation for each signal-to-interference-plus-noise ratio (SINR) constraint and form an iterative algorithm, in which a sequence of SOCPs are solved. The optimal values of SOCPs in the sequence are proved to be non-increasing, and converging to a locally optimal value. In particular, we show that the SDP relaxation is tight for two-user case if one of the SINR constraints is strict (non-binding) at the optimality. Detailed simulation results are presented to demonstrate the performance gains of the NOMA downlink beamforming with per-antenna power constraints through the proposed algorithm, which is compared with some state-of-the-art methods.