FPGA-Based Visible Light Communications Instrument for Implementation and Testing of Ultralow Latency Applications

Abstract

Visible light communication (VLC) employs the modulation of light energy to establish a data connection at a short range. The end-to-end data latency is a significant concern due to the ever-increasing constraints imposed by new applications and standards like sixth generation (6G). To enhance data rate and communication distance, researchers are proposing more calculation-demanding modulation/demodulation techniques. However, implementing these techniques in real-time and ultralow latency environments is challenging. In this article, the authors propose an open system that integrates a programmable VLC front-end with a robust back-end based on a field-programmable gate array (FPGA) to address this challenge. The front-end can drive LEDs with up to 1 A over a bandwidth of 0.01-10 MHz and is programmed via an easy MATLAB interface. With the FPGA framework, users can implement various low-latency VLC applications by modifying a minimal part of the code. The system is demonstrated by implementing two applications: a 1.56-Mb/s link based on chirp coding and a 100-kb/s link based on Manchester modulation that complies with IEEE 802.15.7. In both cases, the bit latency was under 50 µs, and transmission errors were not detected when the input signal-to-noise ratio (SNR) was greater than 1 and −2 dB, respectively.