Nonlinear Power Amplifier-Resilient Cell-Free Massive MIMO: A Joint Optimization Approach

TL;DR

This paper investigates the impact of nonlinear power amplifiers on cell-free massive MIMO systems and proposes joint optimization methods for user association and power control to mitigate performance degradation.

Contribution

It introduces a unified spectral efficiency expression considering nonlinear PA effects and develops a joint optimization framework with a low-complexity approximation.

Findings

Proposed methods outperform conventional techniques in simulations.

Joint optimization significantly improves spectral efficiency.

Low-complexity approach reduces computational overhead.

Abstract

This letter analyzes the effects of power amplifiers (PAs) on the downlink of cell-free massive MIMO systems. We model signal transmission incorporating nonlinear PA distortion and derive a unified spectral efficiency (SE) expression applicable to arbitrary precoding schemes. To combat PA-induced performance degradation, a joint optimization approach for user association and max-min power control is proposed. Furthermore, a low-complexity alternative is developed to approximate the joint optimization with reduced computational overhead. Simulations validate the analysis and demonstrate significant performance gains of the proposed approaches over conventional techniques.