Near-Field Beamforming for Stacked Intelligent Metasurfaces-assisted MIMO Networks

TL;DR

This paper investigates the use of stacked intelligent metasurfaces (SIMs) to enhance near-field MIMO communication systems, demonstrating improved performance through a novel optimization algorithm.

Contribution

It introduces a new formulation for near-field SIM-assisted MIMO systems and proposes an algorithm to optimize performance, highlighting benefits over far-field scenarios.

Findings

Enhanced weighted sum rate in near-field with SIMs

Effective optimization of phase shifts and power allocation

Superior performance compared to far-field conditions

Abstract

Stacked intelligent metasurfaces (SIMs) have recently gained significant interest since they enable precoding in the wave domain that comes with increased processing capability and reduced energy consumption. The study of SIMs and high frequency propagation make the study of the performance in the near field of crucial importance. Hence, in this work, we focus on SIM-assisted multiuser multiple-input multiple-output (MIMO) systems operating in the near field region. To this end, we formulate the weighted sum rate maximisation problem in terms of the transmit power and the phase shifts of the SIM. By applying a block coordinate descent (BCD)-relied algorithm, numerical results show the enhanced performance of the SIM in the near field with respect to the far field.