Reduced Switching Connectivity for Large Scale Antenna Selection

TL;DR

This paper investigates reduced-connectivity RF switching networks for antenna selection in massive MIMO systems, demonstrating that partially-connected architectures improve energy efficiency over fully-flexible switching by minimizing hardware complexity and power losses.

Contribution

It introduces and analyzes partially-connected switching architectures for antenna selection, showing their advantages in energy efficiency over traditional fully-flexible switching.

Findings

Partially-connected switching maximizes energy efficiency in massive MIMO.

Fully-flexible switching introduces significant insertion losses.

Partially-connected architectures reduce hardware complexity and power consumption.

Abstract

In this paper, we explore reduced-connectivity radio frequency (RF) switching networks for reducing the analog hardware complexity and switching power losses in antenna selection (AS) systems. In particular, we analyze different hardware architectures for implementing the RF switching matrices required in AS designs with a reduced number of RF chains. We explicitly show that fully-flexible switching matrices, which facilitate the selection of any possible subset of antennas and attain the maximum theoretical sum rates of AS, present numerous drawbacks such as the introduction of significant insertion losses, particularly pronounced in massive multiple-input multiple-output (MIMO) systems. Since these disadvantages make fully-flexible switching suboptimal in the energy efficiency sense, we further consider partially-connected switching networks as an alternative switching architecture with reduced hardware complexity, which we characterize in this work. In this context, we also analyze the impact of reduced switching connectivity on the analog hardware and digital signal processing of AS schemes that rely on channel power information. Overall, the analytical and simulation results shown in this paper demonstrate that partially-connected switching maximizes the energy efficiency of massive MIMO systems for a reduced number of RF chains, while fully-flexible switching offers sub-optimal energy efficiency benefits due to its significant switching power losses.