Hardware Impairments in Large-scale MISO Systems: Energy Efficiency, Estimation, and Capacity Limits

TL;DR

This paper investigates the fundamental limits of large-scale MISO systems with hardware impairments, revealing that impairments at user terminals limit performance, while array impairments diminish asymptotically, and energy efficiency can be maximized by increasing antennas.

Contribution

It introduces a generalized model for large-scale MISO systems considering hardware impairments and shows how these impairments affect capacity and estimation accuracy.

Findings

Hardware impairments at user terminals limit system performance.

Array impairments become negligible as the number of antennas grows.

Energy efficiency can be increased indefinitely by adding more antennas and reducing power.

Abstract

The use of large-scale antenna arrays has the potential to bring substantial improvements in energy efficiency and/or spectral efficiency to future wireless systems, due to the greatly improved spatial beamforming resolution. Recent asymptotic results show that by increasing the number of antennas one can achieve a large array gain and at the same time naturally decorrelate the user channels; thus, the available energy can be focused very accurately at the intended destinations without causing much inter-user interference. Since these results rely on asymptotics, it is important to investigate whether the conventional system models are still reasonable in the asymptotic regimes. This paper analyzes the fundamental limits of large-scale multiple-input single-output (MISO) communication systems using a generalized system model that accounts for transceiver hardware impairments. As opposed to the case of ideal hardware, we show that these practical impairments create finite ceilings on the estimation accuracy and capacity of large-scale MISO systems. Surprisingly, the performance is only limited by the hardware at the single-antenna user terminal, while the impact of impairments at the large-scale array vanishes asymptotically. Furthermore, we show that an arbitrarily high energy efficiency can be achieved by reducing the power while increasing the number of antennas.