Signal Characterization and Receiver Design for Visible Light Communication Under Weak Illuminance

We characterize the received signals and propose corresponding detection methods for the visible light communication under weak illuminance. Photo-multiplier tube is employed as the receiver, which can amplify weak photon-level signal down to a series of electrons. It is observed that under the extremely low transmission power, the received signals can be characterized by the discontinuous pulses. As the received power increases, the density of the pulses increases, and finally, the received signals form continuous waveforms. We provide the sampling-based and pulse counting-based transmitted symbol detection methods for the continuous signal waveform and the discontinuous pulses, respectively. We further improve the symbol detection performance by combining the two types of detection schemes. Numerical results show that the pulse counting detection can outperform the sampling-based detection with lower sampling rate, and the combined detection can improve the detection performance.