Visible Light Communication
IntroductionBuilt around a cost-effective embedded Linux system, OpenVLC1.0 is an open source, flexible, software-defined, and low-cost platform for research in Visible Light Communication (VLC) Networks. OpenVLC1.0 consists of simple electronic hardware for optical transmission and reception, and of software implementation that runs the MAC layer, part of the PHY layer, and offers an interface to Internet protocols. We have designed and developed a printed circuit board (OpenVLC1.0 cape) that implements a flexible optical front-end. Researchers can plug the cape into the main Beaglebone board and swiftly build and prototype innovative PHY and MAC protocols using the software implementation (OpenVLC1.0 driver). In this work, we provide preliminary measurement results that demonstrate the flexibility of the platform in a few but yet representative scenarios.
Embedded visible light communication (VLC) systems built with low-cost commodity hardware are starting to at- tract the interest of the embedded systems community, but are yet unexplored in many aspects. The performance of VLC channels is not comprehensively studied under different communication settings and scenarios. In this paper we present an experimental characterization of the performance of low-end VLC channels and investigate the impact of various transmitter/receiver settings, protocol-level parameters and deployment aspects using both low-power and high-power LEDs. Our goal is to discover the strengths, weak- nesses and limitations of embedded VLC systems.
The presence of ambient light is a key challenge for reliable and robust low cost embedded visible light communication system. The photodetector used by these systems can perform poorly when subjected to bright ambient light or fluctuating ambient light. To solve this problem, we present an ambient light cancellation mechanism for low cost embedded LED to photodiode communication systems that utilizes a digital potentiometer to adaptively nullify the ambient light to provide an always ZERO output no matter what the ambient light intensity is. The proposed technique allows the receiver to correctly receive the light transmitted by the transmitter without any interference from the ambient light. We provide a detailed description of the modulation and demodulation schemes as well as ambient light cancellation mechanism, and their evaluations. The results show our proposed system can provide a reliable and robust visible light communication with extremely low symbol error rate (almost 0) and an acceptable data rate up to 3kbps given an operating distance of 50 centimeters.
Last updated: December 6, 2016