Movable-Element STAR-RIS for 6G: From Programmable Propagation to Programmable Geometry

2026-09-08

AI Summary

本文提出可移动元素STAR-RIS，通过电磁和几何重构解决无线传播环境中的多径组合、空间相关性等问题，以提高通信效率。

Abstract

Reconfigurable intelligent surfaces (RISs) make the wireless propagation environment programmable, while simultaneously transmitting and reflecting RISs (STAR-RISs) extend this capability to users located on both sides of a surface. However, conventional STAR-RIS architectures retain a fixed physical geometry after deployment. Movable-element STAR-RIS (ME-STAR-RIS) introduces an additional spatial degree of freedom by allowing the surface elements to reposition within prescribed regions while maintaining electronic control of their transmission and reflection responses. This combination of electromagnetic and geometric reconfiguration can alter propagation distances, multipath combinations, spatial correlation, interference, near-field focusing, and sensing geometry. This article presents a system-level perspective on ME-STAR-RIS through the concept of programmable geometry. We discuss its operating principles, movement architectures, and promising applications in communications, security, near-field systems, sensing, and high-mobility networks. A representative case study comparing optimized fixed and movable STAR-RIS architectures illustrates measurable spectral-efficiency gains from limited local displacement and the resulting saturation behavior. Finally, key hardware, channel-acquisition, electromagnetic, energy, reliability, and control challenges are discussed toward practical ME-STAR-RIS deployment.

Problem

• STAR-RIS
• Programmable Geometry
• Wireless Propagation
• Movable-Element
• Spectral Efficiency

Innovation

• Movable-element STAR-RIS
• Programmable Geometry
• Electromagnetic and Geometric Reconfiguration
• Spectral-efficiency Gains
• Reconfigurable Intelligent Surfaces