Large-scale Tunable Liquid Lens-assisted VLC Systems under Random Receiver Orientation

2026-06-15

AI Summary

This study addresses the severe performance degradation in visible light communication (VLC) systems caused by random receiver orientations and dense access point (AP) deployments. To mitigate this issue, the work introduces an electrowetting-based tunable liquid lens into large-scale VLC receivers for the first time, enabling dynamic adjustment of the liquid interface to steer incident light toward the photodiode. By developing an analytically tractable optical channel model that jointly incorporates the spatial distribution of APs (modeled via a Matérn hard-core point process), receiver orientation, and lens steering angle, and by devising optimal signal reception strategies, the authors derive a closed-form expression for the outage probability. Experimental results demonstrate that, under a deployment density of 0.2 m⁻² and an AP height of 3.5 m, the proposed scheme reduces the outage probability by 57.1% compared to conventional fixed-lens receivers, substantially enhancing system robustness.

Abstract

This paper investigates the performance of tunable liquid lens (TLL)-assisted receivers in large-scale visible light communication (VLC) systems under random receiver orientation. A simple electrowetting-based TLL architecture is proposed, capable of dynamically steering the incident optical signal toward the photodiode receiver by adjusting the orientation of the liquid interface. The proposed architecture enhances the desired signal reception while mitigating interference from neighboring access points (APs). The spatial distribution of APs is modeled using a Matérn hard-core point process, whereas receiver orientation is characterized by uniformly distributed azimuth angles and Gaussian-distributed polar angles. Furthermore, a tractable mathematical optical channel model is developed to capture the combined effects of AP/receiver locations, receiver orientation, and lens adjustment angles on the VLC channel gain. Based on this framework, three lens orientation strategies, namely best signal reception (BSR), closest LED selection, and vertical upward lens orientation, are proposed to improve system performance under dynamic receiver conditions. Using stochastic geometry tools, exact and approximate analytical expressions for the outage probability are derived for each scheme. Numerical results verify the accuracy of the developed analysis and demonstrate that the proposed TLL-assisted receiver architecture significantly improves the robustness of VLC systems under severe receiver orientation fluctuations and dense AP deployments. In particular, the BSR scheme reduces the outage probability by $57.1\%$ compared with conventional fixed-lens receivers at an AP height of $3.5$ m and AP density of $0.2~\text{m}^{-2}$. The presented analytical framework and numerical results provide useful design insights for the deployment of future TLL-assisted VLC networks.

Problem

• visible light communication
• random receiver orientation
• tunable liquid lens
• interference mitigation
• outage probability

Innovation

• tunable liquid lens
• visible light communication
• random receiver orientation
• stochastic geometry
• outage probability