Passive Six-Dimensional Movable Antenna (6DMA)-Assisted Multiuser Communication

TL;DR

This paper introduces a passive 6DMA system with adjustable passive IRS surfaces for multiuser uplink communication, optimizing positions, rotations, and reflection coefficients to enhance network capacity.

Contribution

It proposes a novel passive 6DMA system with joint optimization of passive IRS parameters and develops an AO algorithm to solve the non-convex problem.

Findings

Passive 6DMA outperforms fixed-IRS systems in simulations.

Joint optimization significantly improves sum rate.

The AO algorithm effectively handles the complex optimization problem.

Abstract

Six-dimensional movable antenna (6DMA) is a promising solution for enhancing wireless network capacity through the adjustment of both three-dimensional (3D) positions and 3D rotations of distributed antenna surfaces. Previous works mainly consider 6DMA surfaces composed of active antenna elements, thus termed as active 6DMA. In this letter, we propose a new passive 6DMA system consisting of distributed passive intelligent reflecting surfaces (IRSs) that can be adjusted in terms of 3D position and 3D rotation. Specifically, we study a passive 6DMA-aided multiuser uplink system and aim to maximize the users' achievable sum rate by jointly optimizing the 3D positions, 3D rotations, and reflection coefficients of all passive 6DMA surfaces, as well as the receive beamforming matrix at the base station (BS). To solve this challenging non-convex optimization problem, we propose an alternating optimization (AO) algorithm that decomposes it into three subproblems and solves them alternately in an iterative manner. Numerical results are presented to investigate the performance of the proposed passive 6DMA system under different configurations and demonstrate its superior performance over the traditional fixed-IRS counterpart for both directive and isotropic radiation patterns of passive reflecting elements.