Secrecy Capacity Analysis and Beamforming Optimization for MIMO-VLC Wiretap Channels

TL;DR

This paper derives a closed-form expression for the secrecy rate in MIMO-VLC wiretap channels under intensity constraints and proposes beamforming schemes that significantly improve secrecy performance.

Contribution

It introduces a novel secrecy rate expression for MIMO-VLC channels and develops efficient beamforming algorithms to enhance confidentiality.

Findings

Proposed schemes outperform benchmarks in secrecy performance.

Derived a closed-form secrecy rate expression for MIMO-VLC.

Developed convex approximation methods for nonconvex beamforming problems.

Abstract

This paper investigates a multiple-input multipleoutput (MIMO) visible light communication (VLC) wiretap channel consisting of a transmitter, a legitimate receiver, and an eavesdropper. The optical input is subject to both peakand average-intensity constraints. By applying the generalized entropy-power inequality to truncated exponential inputs, we derive a novel closed-form expression for the achievable secrecy rate for general MIMO VLC configurations. To enhance transmission confidentiality, a fully-connected beamforming scheme is proposed, along with a low-complexity sub-connected alternative. Although the resulting beamforming design problems are nonconvex, they are efficiently addressed by transforming them into a sequence of convex subproblems solvable via the successive convex approximation framework. Numerical results demonstrate that the proposed schemes achieve significant secrecy performance improvements compared with the benchmark scheme.