Multipair Massive MIMO Two-Way Full-Duplex Relay Systems with Hardware Impairments

TL;DR

This paper analyzes the impact of hardware impairments on multipair massive MIMO two-way full-duplex relay systems, deriving spectral efficiency expressions, a hardware scaling law, and optimal antenna number for energy efficiency.

Contribution

It introduces a novel hardware scaling law for massive MIMO relay systems and provides practical design insights for low-cost, high-performance implementations.

Findings

Spectral efficiency expressions derived for impaired systems

Hardware impairments scale roughly with the square root of antenna number

Optimal relay antenna count maximizes energy efficiency

Abstract

Hardware impairments, such as phase noise, quantization errors, non-linearities, and noise amplification, have baneful effects on wireless communications. In this paper, we investigate the effect of hardware impairments on multipair massive multiple-input multiple-output (MIMO) two-way full-duplex relay systems with amplify-and-forward scheme. More specifically, novel closed-form approximate expressions for the spectral efficiency are derived to obtain some important insights into the practical design of the considered system. When the number of relay antennas $N$ increases without bound, we propose a hardware scaling law, which reveals that the level of hardware impairments that can be tolerated is roughly proportional to $\sqrt{N}$. This new result inspires us to design low-cost and practical multipair massive MIMO two-way full-duplex relay systems. Moreover, the optimal number of relay antennas is derived to maximize the energy efficiency. Finally, Motor-Carlo simulation results are provided to validate our analytical results.