Distortion-Aware Beamforming Design for MU-MISO Systems

The non-linearity of power amplifiers (PAs) in multiple antenna transmitters will cause spatial distortions and beam dispersion, which may lead to significant performance degradation. In this paper, we investigate the distortion-aware beamforming design in a multiuser multiple-input single-output (MU-MISO) system. Using a typical third-order memoryless polynomial distortion model, the impact of the nonlinear PA on the performance of MU-MISO is firstly analyzed by evaluating the receive signal-to-interference-plus-noise ratio (SINR) of UEs. Then, we aim to propose a distortion-aware beamforming scheme that can effectively pre-compensate for the beam dispersion caused by nonlinear PA distortion. Our objective is to maximize the sum-rate under the constraint of the transmit power by considering the effect of nonlinear PA distortion. The complex non-convex optimization problem is efficiently solved by an alternating optimization algorithm that utilizes the fractional programming (FP), penalty-based, and majorization-minimization (MM) methods. Finally, simulation studies demonstrate the substantial performance improvement achieved by utilizing the proposed distortion-aware beamforming scheme to mitigate nonlinear PA distortion and confirm the effectiveness of the developed beamforming design algorithm.