Secure Visible Light Communications via Intelligent Reflecting Surfaces

Abstract

Intelligent reflecting surfaces (IRS) can improve the physical layer security (PLS) by providing a controllable wireless environment. In this paper, we propose a novel PLS technique with the help of IRS implemented by an intelligent mirror array for the visible light communication (VLC) system. First, for the IRS aided VLC system containing an access point (AP), a legitimate user and an eavesdropper, the IRS channel gain and a lower bound of the achievable secrecy rate are derived. Further, to enhance the IRS channel gain of the legitimate user while restricting the IRS channel gain of the eavesdropper, we formulate an achievable secrecy rate maximization problem for the proposed IRS-aided PLS technique to find the optimal orientations of mirrors. Since the sensitivity of mirrors' orientations on the IRS channel gain makes the optimization problem hard to solve, we transform the original problem into a reflected spot position optimization problem and solve it by a particle swarm optimization (PSO) algorithm. Our simulation results show that secrecy performance can be significantly improved by adding an IRS in a VLC system.

RIS-Assisted Visible Light Communication Systems: A Tutorial

“…Hence, the use of RISs in VLC is motivated by two main reasons, namely solving the skip-zone and device orientation problems, and enhancing the performance of VLC transmitters and receivers. Although, there have been few studies on the integration of RISs and VLC [42], [44], [46], [47], [140], [141], the potential role of RISs in the context of VLC systems has not been well explored in the literature, and that is the focus of this section.…”

“…25 are surveyed under the following design topics: (1) RIS elements orientation design, (2) RIS elements to AP/user assignment design, and (3) RIS array positioning design. The objective of these design topics is to properly utilize the elements (i.e., mirrors or metasurfaces) of the RIS array to improve key performance indicators such as achievable data rate [42], [46], energy efficiency [43], spectral efficiecny [47], and secrecy rate [44].…”

“…Performing an exhaustive search to obtain the global optimal solution for the problem of the form in ( 1) is computationally prohibitive even for an array with a small number of elements. Only a handful studies (i.e., [42]- [44]) have attempted such a problem. Among those works, population based intelligent heuristic schemes (i.e., meta-heuristics) have been shown to be the appropriate method for overcoming the difficulties of solving (1).…”

“…In [44], a secrecy rate optimization problem was studied for an RIS-assisted VLC system. In this work, the authors focused on exploiting RIS mirror arrays in VLC to develop a secured communication system.…”

“…On the other hand, PLS techniques have been a huge success in improving the security of RF communication networks [164]- [166], and has therefore recently been considered for VLC systems. An in-depth survey of earlier works on PLS-VLC can be found in [161], [167] and the most recent studies in [44], [168]- [175].…”