Non-linearity of LEDs for VLC IoT applications
Visible light communication (VLC) is a promising technology to satisfy the increasing demand of wireless communication services. The generalized idea of modulating the signal within the light-emitting diode (LED) linear region is considered the de-facto approach for high-speed communication. This paper shows that this is not the most appropriate choice for the Internet of Things (IoT) applications, where the communication range is of greater importance once a sufficient communication rate is reached. In order to improve the communication range, we propose to exploit the full non-linear region of an LED transceiver while maintaining constant illumination. We show that working in the full LED region can provide received electrical power gains in the mobile IoT tag of around 15 dB. We achieve this without affecting the communication rate for IoT applications, and at the penalty of about 10% increase in the total energy consumption of LEDs. We further demonstrate that exploiting the non-linear region of LEDs is beneficial for mobile tags that employ a solar cell for receiving data at high data rates.