Joint beamforming and PAPR reduction in massive MIMO: analysis of gain in energy efficiency

Abstract

The main goal of this article is to accurately quantify the gain in energy efficiency that can be obtained by combining PAPR reduction techniques with beamforming in the context of massive MIMO communications. To this purpose, we first derive and analyze the expressions of sum capacity, power consumption, and energy efficiency for hybrid, digital and analog beamforming for massive MIMO systems in the millimeter wave frequency range. Then, we use these results to derive and quantify the gain in energy efficiency at system level that can be obtained by combining PAPR reduction for improved power amplifier efficiency with beamforming in massive MIMO systems. Inaddition, we derive the expressions allowing to determine the optimal amount of antennas M that should be connected to each RF chain in a partially connected hybrid beamforming scheme in order to maximize the systems energy efficiency. Evaluation of the derived expressions clearly show that a noticeable gain in the systems energy efficiency is obtained when PAPR reduction is added, and allows to analyze the advantages and disadvantages of each approach from an energy efficiency point of view.