Onderzoek van Visible Light Communication voor Indoor Lokatiebepaling

Until today, the existing technological solutions for accurate indoor positioning do not have a sufficient accuracy and require expensive equipment to be practically useful. At the same time, there is the arrival of the Light Emitting Diode (LED) which provides a new form of lighting for different applications. Compared to other lighting technologies, LEDs have an additional interesting property, namely that the light can be modulated at high speed. This has led to a new technological challenge, namely the usage of the existing infrastructure of LED lighting in combination with a wireless link for data communication. Visible Light Communication (VLC) has a number of advantages compared to RF communication: the frequency band is not licensed and a number of orders wider, the data is better protected due to the local character, there are no EMC problems with other electronic equipment, ... In this PhD, we want to explore the unique properties of LEDs (especially the high modulation speeds and the local character of the light) for indoor positioning. Starting with the characterization of the LED, receiver and channel, we will gradually progress to the realization of a working proof-of-concept for indoor positioning. The solution should work without disturbing the original function of the LEDs, namely to illuminate the room according to the lighting standards (when required with possibility for dimming) when there is communication. For a robust solution, it is important to characterize all kinds of optical noise sources, which comes down to the definition of a good channel model. Another aspect of the PhD is the research of a multipoint (set of LED fixtures in the lighting infrastructure) to point (mobile) topology, as it is perfectly possible to receive the emitted light from different LEDs at the same time. An appropriate coding technique and a solution to determine the relative signal strength is essential for the technology to succeed. Therefore, the definition of a robust multiple access technology for a multipoint-to-point topology is required with light as a carrier of information. In many cases, the encoding is oriented towards the maximization of the data rate in point-to-point links. These technologies typically target applications for the establishment of a bi-directional high data rate link using VLC over short distances (typically a desk lamp to a computer, the headlights in an aircraft, ...). It is clear that for these applications, the optical interference (noise) and multiple access does not play an important role. However, we wish to develop a coding technique which is specifically designed for use in combination with a robust multiple access technology in a multi-point-to-point topology. The solution should not only be examined in a static environment but also the dynamic behavior (using soft handovers) might be critical for some application.nrpages: 168status: publishe