Secrecy Capacity of Hybrid VLC-RF Systems with Light Energy Harvesting

TL;DR

This paper investigates the physical layer security of a hybrid VLC-RF system with energy harvesting, optimizing time slots to maximize secrecy capacity while supporting simultaneous information transfer and power harvesting.

Contribution

It introduces an optimization framework for maximizing secrecy capacity in a hybrid VLC-RF system with energy harvesting, using DC programming and DCA.

Findings

Optimal time slot allocation enhances secrecy capacity.

The DC algorithm efficiently solves the formulated optimization problem.

The proposed scheme improves security in energy-harvesting hybrid systems.

Abstract

This paper studies the performance of physical layer security (PLS) in a multi-user hybrid heterogeneous visible light communication (VLC) and radio frequency (RF) wireless communication system with simultaneous lightwave information and power transfer (SLIPT). In the considered system, VLC is used for downlink (DL) while RF is employed for uplink (UL) transmission. In addition, to support multiple users, time division multiple access (TDMA) is assumed for both DL and UL channels. In the DL, each user receives information during its allocated time slot of the TDMA frame and harvests energy from the received signal outside the time slot. The harvested energy is then used for transmitting the signal over the UL channel, which is subject to eavesdropping by an unauthorized user. Therefore, PLS is employed to protect the confidentiality of the UL information. Then, an optimization problem is formulated to solve the optimal DL and UL time slots that maximize the PLS performance given a target sum rate of the DL. We show that the problem can be cast as a difference of convex functions (DC) program, which can be solved efficiently using the DC algorithm (DCA).