VLC-LE: Energy-Efficient and Secure Visible Light Communication for the Internet of Bodies

We present VLC-LE, a low-energy variant of Visible Light Communication (VLC) for energy-constrained devices such as on-body wearables that collect and transmit sensitive health data. VLC-LE is ultra-low-power and physically secure compared to traditional VLC, BLE, or WiFi. VLC-LE transmits data by modulating the LED at extremely low brightness levels by biasing it below its knee voltage, a method unique to VLC-LE and not previously explored in VLC technologies. The peak power consumption of VLC-LE is far less
$(\approx 10\mu \mathrm{W}), 100$
times lower, compared to
$(\approx \text{mW})$
power consumed by traditional VLC, BLE and WiFi. Additionally, the low brightness levels of the LED in VLC-LE limit the signal transmission range to a few centimeters, improving the physical-layer security of the communication. Our specific contributions are as follows: We prototype the first version of VLC-LE, demonstrating data transfers from an embedded device to a smartphone. We created a dataset comprising 48,000 images of an LED at different brightness levels and ambient light conditions. We used this dataset to study the effect of VLC-LE on LED brightness and ambient conditions. The study helped us determine the lowest brightness level and, thus. the lowest power required for operating VLC-LE.