Single Edge Position Modulation as a Dimming Technique for Visible Light Communications

In this paper, a power switched, baseband modulation technique for visible light communications (VLC) is proposed and a theoretical model is constructed. It is shown that this technique, called single edge position modulation (SEPM), offers the unique performance characteristic that the communication properties reliability and power and spectral efficiency are invariable over a wide range of dimming levels. It is demonstrated that dimming robustness is obtained by increasing the number of bits per symbol. SEPM is compared with contemporary used baseband power switched modulation techniques for VLC that support dimming. The number of bits per symbol can be chosen to make a compromise between the dimming range over which reliability robustness is obtained on one hand, and the level of power and spectral efficiency on the other hand.