Multi-Functional Programmable Metasurfaces for 6G and Beyond

TL;DR

This paper surveys multi-functional programmable metasurfaces enabling full-space communication, ubiquitous sensing, and intelligent signal processing for 6G and beyond, highlighting recent advances and future challenges.

Contribution

It provides a comprehensive overview of multi-functional programmable metasurfaces, detailing their applications in communication, sensing, and computing for future wireless networks.

Findings

STARS-enabled full-space communication protocols analyzed

Advantages of PM-assisted sensing in near-field and multi-band operations demonstrated

Stacked intelligent metasurfaces enable wave-domain analog processing and over-the-air computing

Abstract

The sixth-generation and beyond (B6G) networks are envisioned to support advanced applications that demand high-speed communication, high-precision sensing, and high-performance computing. To underpin this multi-functional evolution, energy- and cost-efficient programmable metasurfaces (PMs) have emerged as a promising technology for dynamically manipulating electromagnetic waves. This paper provides a comprehensive survey of representative multi-functional PM paradigms, with a specific focus on achieving \emph{full-space communication coverage}, \emph{ubiquitous sensing}, as well as \emph{intelligent signal processing and computing}. i) For simultaneously transmitting and reflecting surfaces (STARS)-enabled full-space communications, we elaborate on their operational protocols and pivotal applications in supporting efficient communications, physical layer security, unmanned aerial vehicle networks, and wireless power transfer. ii) For PM-underpinned ubiquitous sensing, we formulate the signal models for the PM-assisted architecture and systematically characterize its advantages in near-field and cooperative sensing, while transitioning to the PM-enabled transceiver architecture and demonstrating its superior performance in multi-band operations. iii) For advanced signal processing and computing, we explore the novel paradigm of stacked intelligent metasurfaces (SIMs), investigating their implementation in wave-domain analog processing and over-the-air mathematical computing. Finally, we identify key research challenges and envision future directions for multi-functional PMs towards B6G.