# Signal Demodulation with Machine Learning Methods for Physical Layer Visible Light Communications: Prototype Platform, Open Dataset and Algorithms

## TL;DR

This paper develops and tests machine learning-based demodulation techniques for visible light communication systems, using a real hardware prototype and open dataset, demonstrating the effectiveness of CNN, DBN, and AdaBoost methods.

## Contribution

It introduces three novel ML demodulators for VLC, supported by a hardware prototype and an open dataset, advancing data-driven physical layer communication methods.

## Key findings

- AdaBoost achieves the highest demodulation accuracy among the three methods.
- Demodulation accuracy decreases with increased transmission distance.
- Higher modulation orders reduce demodulation accuracy at a fixed distance.

## Abstract

In this paper, we investigate the design and implementation of machine learning (ML) based demodulation methods in the physical layer of visible light communication (VLC) systems. We build a flexible hardware prototype of an end-to-end VLC system, from which the received signals are collected as the real data. The dataset is available online, which contains eight types of modulated signals. Then, we propose three ML demodulators based on convolutional neural network (CNN), deep belief network (DBN), and adaptive boosting (AdaBoost), respectively. Specifically, the CNN based demodulator converts the modulated signals to images and recognizes the signals by the image classification. The proposed DBN based demodulator contains three restricted Boltzmann machines (RBMs) to extract the modulation features. The AdaBoost method includes a strong classifier that is constructed by the weak classifiers with the k-nearest neighbor (KNN) algorithm. These three demodulators are trained and tested by our online open dataset. Experimental results show that the demodulation accuracy of the three data-driven demodulators drops as the transmission distance increases. A higher modulation order negatively influences the accuracy for a given transmission distance. Among the three ML methods, the AdaBoost modulator achieves the best performance.