Generalized Likelihood Block Detection for SPAD-Based Underwater VLC System

In the underwater visible light communication (VLC) system, the single-photon avalanche diode (SPAD) can expand communication distance. However, the output signals from practical SPADs under dead time limit are not Poisson distributed. In this paper, the generalized likelihood block detection (GLBD) receiver is developed for practical SPAD-based underwater VLC system with on-off keying modulation. The proposed receiver can detect the data sequence without any prior knowledge of the channel and the background radiation. Correspondingly, a fast search algorithm for GLBD receiver is also proposed. In addition, a block coding scheme is utilized to solve the error floor problem. Simulation results show that the bit error rate (BER) performance of the proposed receiver is closer to the BER low bound compared to the existing receiver. Moreover, the fast search algorithm reduces the computational complexity without any performance loss.