Energy-Efficient Transmit Beamforming and Antenna Selection with Non-Linear PA Efficiency

TL;DR

This paper proposes an energy-efficient transmit beamforming and antenna selection method for multi-user MIMO systems that accounts for non-linear PA efficiency and RF chain power, using a sequential convex approximation algorithm.

Contribution

It introduces a novel joint optimization framework for beamforming and antenna selection considering practical non-linear PA and RF power models, solved via SCA.

Findings

Fewer antennas are activated at the optimal solution.

Higher power transmission per antenna improves PA efficiency.

The proposed algorithm effectively reduces total power consumption.

Abstract

This letter studies the energy-efficient design in a downlink multi-antenna multi-user system consisting of a multi-antenna base station (BS) and multiple single-antenna users, by considering the practical non-linear power amplifier (PA) efficiency and the on-off power consumption of radio frequency (RF) chain at each transmit antenna. Under this setup, we jointly optimize the transmit beamforming and antenna on/off selection at the BS to minimize its total power consumption while ensuring the individual signal-to-interference-plus-noise ratio (SINR) constraints at the users. However, due to the non-linear PA efficiency and the on-off RF chain power consumption, the formulated SINR-constrained power minimization problem is highly non-convex and difficult to solve. To tackle this issue, we propose an efficient algorithm to obtain a high-quality solution based on the technique of sequential convex approximation (SCA). We provide numerical results to validate the performance of our proposed design. It is shown that at the optimized solution, the BS tends to activate fewer antennas and use higher power transmission at each antenna to exploit the non-linear PA efficiency.