Relative Localization for Mobile Nodes using Visible Light

A growing number of wireless devices and increasing traffic in the radio spectrum has pushed for alternatives to radio based communication. Among these, communication using visible light (VLC) has gained considerable momentum. The imminent adoption of energy efficient Light Emitting Diodes (LEDs) and the high data transmission rates offered by VLC has greatly contributed to the spread of visible light as a competitive communication medium. Apart from communication, another area greatly benefiting from visible light is localization. A significant amount of work has been done in localization for VLC based networks, however most of the methods proposed are dependant on either surrounding environments or require multiple reference points at fixed positions for localization. These dependencies greatly restrict localization for scenarios where a lot of mobility is involved, such as vehicles on a road, or robots in an industrial environment. This master thesis presents a localization model which can be used to find the relative position of devices or nodes without such dependencies. Compared to the existing work in this field, in our proposed model, nodes are free to move and rotate in any direction, and only require a single light source for position estimation. We present a mathematical model for relative localization and a software implementation to visualize the location of nodes in real-time. Results from experiments conducted in both static and mobile settings under different illumination levels validate our proposed model. These results also highlight the effect of errors in received power and orientation of nodes on localization accuracy. Our work indicates that this proposed model can be further extended and implemented in a real world scenario.