On the Spectral Efficiency of Movable and Rotary Antenna Arrays under Rician Fading

TL;DR

This paper investigates the spectral efficiency of movable and rotary antenna arrays in Rician fading environments, proposing a cost-effective rotary array system that enhances performance through optimized movement and rotation.

Contribution

It introduces a simpler, cheaper rotary antenna array system and analyzes its performance with movement and rotation optimization in Rician fading channels.

Findings

Rotary antenna arrays can outperform movable antenna arrays under movement constraints.

Optimized movement and rotation significantly improve spectral efficiency in line-of-sight dominant channels.

Both movement and rotation contribute to performance gains in Rician fading environments.

Abstract

Most works evaluating the performance of Multi-User Multiple-Input Multiple-Output (MU-MIMO) systems consider Access Points (APs) with fixed antennas, that is, without any movement capability. Recently, the idea of APs with antenna arrays that are able to move have gained traction among the research community. Many works evaluate the communications performance of Movable Antenna Arrays (MAAs) that can move on the horizontal plane. However, they require a very bulky, complex and expensive movement system. In this work, we propose a simpler and cheaper alternative: the utilization of Rotary Antenna Arrays (RAA)s, i.e. antenna arrays that can rotate. We also analyze the performance of a system in which the array is able to both move and rotate. The movements and/or rotations of the array are computed in order to maximize the mean per-user achievable spectral efficiency, based on estimates of the locations of the active devices and using particle swarm optimization. We adopt a spatially correlated Rician fading channel model, and evaluate the resulting optimized performance of the different setups in terms of mean per-user achievable spectral efficiencies. Our numerical results show that both the optimal rotations and movements of the arrays can provide substantial performance gains when the line-of-sight components of the channel vectors are strong. Moreover, the simpler RAAs can outperform the MAAs when their movement area is constrained.