Energy-Efficient Precoding Designs for Multi-User Visible Light Communication Systems with Confidential Messages

TL;DR

This paper proposes low-complexity energy-efficient precoding algorithms for secure multi-user visible light communication systems, balancing secrecy, power consumption, and system performance through convex-concave and relaxation techniques.

Contribution

It introduces novel sub-optimal precoding solutions for maximizing energy efficiency with secrecy constraints in VLC systems, using CCCP, SDR, and ZF methods.

Findings

Proposed algorithms achieve good secrecy and energy efficiency.

Algorithms demonstrate convergence and adaptability to system parameters.

Numerical results validate the effectiveness of the methods.

Abstract

This paper studies energy-efficient precoding designs for multi-user visible light communication (VLC) systems from the perspective of physical layer security where users' messages must be kept mutually confidential. For such systems, we first derive a lower bound on the achievable secrecy rate of each user. Next, the total power consumption for illumination and data transmission is thoroughly analyzed. We then tackle the problem of maximizing energy efficiency, given that each user's secrecy rate satisfies a certain threshold. The design problem is shown to be non-convex fractional programming, which renders finding the optimal solution computationally prohibitive. Our aim in this paper is, therefore, to find sub-optimal yet low complexity solutions. For this purpose, the traditional Dinkelbach algorithm is first employed to reformulate the original problem to a non-fractional parameterized one. Two different approaches based on the convex-concave procedure (CCCP) and Semidefinite Relaxation (SDR) are utilized to solve the non-convex parameterized problem. In addition, to further reduce the complexity, we investigate a design using the zero-forcing (ZF) technique. Numerical results are conducted to show the feasibility, convergence, and performance of the proposed algorithms depending on different parameters of the system.