Iterative Decision-Directed Receiver for the Mitigation of Side-Effect Modulation in indoor VLC applications

Side effect modulation (SEM) has been shown to be an important impairment in visible light communication (VLC) systems. SEM is the unintended modulation of the light caused by the switched mode power supplies which are often used in light emitting diode (LED) luminaires. These power supplies may result in fluctuations in the driving current. In this paper, we investigate the performance of VLC in two different configurations. In both configurations, simulation results show that even low levels of SEM can substantially degrade the performance for most receiver positions. An iterative decision-directed receiver is described which mitigates the effect of SEM. In this receiver, the fundamental frequency component of SEM is estimated and removed from the received signal. The iterative processing is used to improve the estimation accuracy and thus improve performance. The iterative receiver is compared to the previously described decision-directed and pilot-assisted receivers. It is shown that, with only two iterations, the iterative decision-directed receiver effectively mitigates the impact of SEM.