Nonlinear compensation for indoor visible light communication systems with carrierless amplitude and phase modulation

Although there are enormous available bandwidths for license-free visible light communication (VLC), a relatively narrow modulation bandwidth of LED is still an obstacle for further application. The carrierless amplitude and phase (CAP) modulation is a high spectral efficiency modulation technology which has begun to draw more attention in recent years. However, to meet the illumination of indoor VLC, the nonlinear interference is quite serious because of multipath fading channels. Thus, the spectrum efficiency of VLC with CAP modulation is greatly limited by these nonlinear effects. In this paper, the nonlinear distortion of indoor VLC systems, which was introduced by the nonlinearity of analog device and multipath fading channel, has been analyzed. Therefore, the problem we are trying to solve is to study an adaptive digital equalizer at CAP modulation which can efficiently mitigate nonlinearity of indoor VLC. The simulation result shows that the adaptive digital decision-feedback equalizer is an effective solution that can mitigate inter-symbol interference and improve the receiver performance efficiently.