Tight Capacity Bounds for Indoor Visible Light Communications With Signal-Dependent Noise

TL;DR

This paper derives tight capacity bounds for indoor visible light communication systems considering signal-dependent noise and optical intensity constraints, providing analytical expressions and numerical validation.

Contribution

It introduces novel closed-form capacity bounds for VLC with signal-dependent noise under practical optical constraints, advancing theoretical understanding.

Findings

Capacity bounds are tightly characterized with closed-form expressions.

Asymptotic analysis shows the bounds converge at high signal levels.

Numerical results confirm the accuracy of the derived bounds.

Abstract

Channel capacity bounds are derived for a point-to-point indoor visible light communications (VLC) system with signal-dependent Gaussian noise. Considering both illumination and communication, the non-negative input of VLC is constrained by peak and average optical intensity constraints. Two scenarios are taken into account: one scenario has both average and peak optical intensity constraints, and the other scenario has only average optical intensity constraint. For both two scenarios, we derive closed-from expressions of capacity lower and upper bounds. Specifically, the capacity lower bound is derived by using the variational method and the property that the output entropy is invariably larger than the input entropy. The capacity upper bound is obtained by utilizing the dual expression of capacity and the principle of "capacity-achieving source distributions that escape to infinity". Moreover, the asymptotic analysis shows that the asymptotic performance gap between the capacity lower and upper bounds approaches zero. Finally, all derived capacity bounds are confirmed using numerical results.