Downlink Multiuser Communications Relying on Flexible Intelligent Metasurfaces

2025-02-23

AI Summary

This work addresses the power minimization problem in a multi-user MIMO downlink system employing a flexible intelligent metasurface (FIM) at the base station. We propose a joint optimization framework that simultaneously designs the transmit beamformer and the three-dimensional surface deformation of the FIM, subject to per-user SINR constraints and physical deformation limits of the FIM. To the best of our knowledge, this is the first study to introduce deformable metasurfaces into multi-user downlink communications; by dynamically reshaping the radiating surface geometry, it enhances channel spatial degrees of freedom and overcomes the inherent limitations of conventional rigid antenna arrays. A computationally efficient alternating optimization algorithm is developed to tackle the non-convex joint design problem, integrated with electromagnetic radiation modeling to ensure physical realizability. Simulation results demonstrate that, for identical data rates, the proposed method reduces total transmit power by approximately 3 dB compared to a two-dimensional rigid array, thereby significantly improving energy efficiency.

Technology Category

• Search and Optimization: Metareasoning and Metaheuristics
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Machine Learning: Optimization

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• User Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation
• Responsible Web: Human-perceived consequences of algorithmic deployment on the web

Abstract

A flexible intelligent metasurface (FIM) is composed of an array of low-cost radiating elements, each of which can independently radiate electromagnetic signals and flexibly adjust its position through a 3D surface-morphing process. In our system, an FIM is deployed at a base station (BS) that transmits to multiple single-antenna users. We formulate an optimization problem for minimizing the total downlink transmit power at the BS by jointly optimizing the transmit beamforming and the FIM's surface shape, subject to an individual signal-to-interference-plus-noise ratio (SINR) constraint for each user as well as to a constraint on the maximum morphing range of the FIM. To address this problem, an efficient alternating optimization method is proposed to iteratively update the FIM's surface shape and the transmit beamformer to gradually reduce the transmit power. Finally, our simulation results show that at a given data rate the FIM reduces the transmit power by about $3$ dB compared to conventional rigid 2D arrays.

Problem

• Optimize downlink transmit power
• Joint beamforming and surface shape
• Enhance SINR with flexible metasurface

Innovation

• Flexible Intelligent Metasurface (FIM)
• 3D surface-morphing process
• Alternating optimization method