Channel Modeling and LED Spot Detection for Dense Image-Sensor Visible Light Communication

2026-05-17

AI Summary

This work addresses severe inter-symbol interference in visible light communication (VLC) using image sensors, caused by blurred and overlapping high-density LED array spots along with radial distortion and vignetting effects. To tackle this challenge, the paper proposes a robust decoding framework that preserves full signaling density by integrating multiple novel components: pilot-structure priors, a point spread function (PSF)-constrained Hough transform, circle-center alignment optimization, radial distortion correction, and vignetting-aware compensation. This integrated approach enables precise separation of overlapping light spots and accurate recovery of geometric consistency. Evaluated on a real-world VLC testbed, the method substantially outperforms conventional Hough transform techniques and low-density baselines, achieving significantly higher decoding accuracy and throughput under strong interference conditions.

Abstract

High-density LED arrays enable high-speed transmission in image-sensor-based visible-light communication (VLC) systems. However, when optical spots become blurred and spatially overlapped due to focal shift, resolution limitations, or interference, severe inter-symbol interference (ISI) occurs, significantly degrading decoding performance. Furthermore, radial distortion introduces geometric deformation of the LED grid, while vignetting leads to incomplete and asymmetric spot shapes at the periphery, both of which further hinder reliable signal detection. Existing methods mitigate ISI by reducing LED transmission signaling density. This paper proposes a robust decoding framework that maintains full LED signaling density. We introduce a pilot-aided geometric recognition method that uses a PSF-constrained Hough transform and circle-center alignment refinement. \textbf{In addition, radial distortion correction and vignetting-aware compensation are incorporated to restore geometric consistency and suppress edge-related detection errors.} By leveraging prior structural knowledge from pilot frames, the system effectively separates overlapping LED signals under severe optical distortion. Experimental results on a real-world VLC testbed confirm that the proposed method achieves superior decoding accuracy and throughput compared to conventional Hough-based and low-density baseline methods. The results highlight its potential for high-efficiency VLC applications in interference-prone environments.

Problem

• inter-symbol interference
• radial distortion
• vignetting
• LED spot detection
• visible light communication

Innovation

• visible light communication
• image sensor
• inter-symbol interference
• radial distortion correction
• vignetting compensation