For indoor visible light communications (VLC) to be adopted, it is imperative that the LED lighting infrastructure fulfills its primary function of providing desired illumination while using the light bulbs as wireless access points. To achieve this, it is desirable to decouple dynamic illumination control from communication control while maximizing achievable data rates for a mobile user. To achieve this, we have created a framework based on a mathematical technique called singular value decomposition (SVD).
The SVD-VLC system controller accepts as inputs (i) data to be transmitted and (ii) the desired illumination within the room. It is assumed the controller knows what fraction of light from each light bulb is collected by the receiver(s). Based on this information, the controller optimally generates (a) I2 streams: parallel signals that transmit data while providing illumination (b) I1 streams: parallel signals that provide only illumination. The I1 and I2 streams are optimally combined to generate one drive signal for each luminaire. In response to these drive signals, the luminaires generate equivalent output light. The light, while propagating through indoor space, mixes to produce desired illumination. At the receiver(s), optics and optical filters are used to separate and recover the data from the different I2 streams.
A technical report on the SVD-VLC system can be found here