Comparison of Hybrid DCO-OFDM-PWM and DCO- OFDM-PPM Schemes in Cellular Channel

Optical orthogonal frequency division multiplexing (O-OFDM) based visible light communication (VLC) systems severely suffer from high peak-to-average-power-ratio (PAPR) induced nonlinear distortion due to the non-linearity of the light emitting diode (LED). One possible solution to this problem is to convert OFDM into a digital format prior to intensity modulation of the light source. In this paper, we present the hybrid OFDM- pulse time modulation scheme, and outline the performance of DCO-OFDM-PWM and PPM for cellular and LOS channels. The simulation results show that the cellular configuration offer marginally higher bit error rate (BER) performance compared with the LOS link. Furthermore, we show that the DCO-OFDM- PWM scheme offers an improved BER performance for lower modulation orders compared with the DCO-OFDM-PPM scheme for the cellular channel.