FPGA-Based Visible Light Communications Instrument for Implementation and Testing of Ultralow Latency Applications
Stefano Ricci, Stefano Caputo, Lorenzo Mucchi
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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$50 \mu \text{s}$ </tex-math></inline-formula> , and transmission errors were not detected when the input signal-to-noise ratio (SNR) was greater than 1 and −2 dB, respectively.