Investigation of code division multiplexing technique for VLC-based indoor positioning

The visible light communication (VLC) with LED lamps is a very promising technique which can be a possible alternative to certain simplex radio connections aiming to relieve the quickly saturating radio frequency domain. The advantages of visible light communication can be exploited by indoor applications most efficiently. Because - similarly to radio communications - it may be necessary to run more connections simultaneously, the signals of each transmitter must be discriminable. A certain method that ensures the discriminability of signals is code division multiplexing (CDM). In this multiplexing method the channels share a common frequency band but the signals of different transmitters use digital modulation with different quasi-orthogonal codes. In my study I show step-by-step how to realize a VLC CDM system. I approximate the parameters of a system of this type by simulation models, design the software to real-time communication and verify the functionality of VLC CDM scheme with visible light demonstration circuits.