Appropriate modulation scheme for visible light communication systems considering illumination

Visible light communication (VLC) systems use light emitting diode (LED) technology for illumination and data transmission at the same time. The main concerns of VLC systems are illumination and BER performance. In optical systems, the modulation scheme affects the illumination and BER. Therefore, it is necessary to analyse the performance of the modulation schemes applied in the VLC system. To analyse the bandwidth requirement, power efficiency, brightness and flickering problem, four different modulation schemes, were compared: OOK, pulse position modulation (PPM), overlapping PPM (OPPM), and inverted PPM (I-PPM). It is shown that OPPM achieves better performance with flexible illumination. Moreover, trellis-coded modulation (TCM) is applied to improve the BER performance. Simulation results show that OPPM is a powerful candidate modulation scheme for VLC systems.