Smart and Secure Wireless Communications via Reflecting Intelligent Surfaces: A Short Survey

TL;DR

This survey reviews the integration of reconfigurable intelligent surfaces (RIS) with physical layer security (PLS) techniques to enhance wireless communication security, highlighting recent advances, methodologies, and future research directions.

Contribution

It provides a comprehensive classification and analysis of RIS-assisted PLS applications, summarizing optimization approaches and identifying open challenges in the field.

Findings

Most works optimize secrecy rate or capacity via joint beamforming and RIS configuration.

Optimization problems vary in methodology, including exact and sub-optimal solutions.

The survey highlights open problems and future research directions in RIS-assisted PLS.

Abstract

With the emergence of the internet of things (IoT) technology, wireless connectivity should be more ubiquitous than ever. In fact, the availability of wireless connection everywhere comes with security threats that, unfortunately, cannot be handled by conventional cryptographic solutions alone, especially in heterogeneous and decentralized future wireless networks. In general, physical layer security (PLS) helps in bridging this gap by taking advantage of the fading propagation channel. Moreover, the adoption of reconfigurable intelligent surfaces (RIS) in wireless networks makes the PLS techniques more efficient by involving the channel into the design loop. In this paper, we conduct a comprehensive literature review on the RIS-assisted PLS for future wireless communications. We start by introducing the basic concepts of RISs and their different applications in wireless communication networks and the most common PLS performance metrics. Then, we focus on the review and classification of RIS-assisted PLS applications, exhibiting multiple scenarios, system models, objectives, and methodologies. In fact, most of the works in this field formulate an optimization problem to maximize the secrecy rate (SR) or secrecy capacity (SC) at a legitimate user by jointly optimizing the beamformer at the transmitter and the RIS's coefficients, while the differences are in the adopted methodology to optimally/sub-optimally approach the solution. We finalize this survey by presenting some insightful recommendations and suggesting open problems for future research extensions.