Enhanced performance of an indoor non-line-of-sight VLC system utilizing a multi-pixel photon counter and interleaved single-carrier FDM scheme

A non-line-of-sight (NLOS) visible light communication (VLC) system, utilizing a multi-pixel photon counter (MPPC) as the detector and interleaved single-carrier frequency division multiplexing (I-SC-FDM) scheme, was first proposed and experimentally investigated in this work. Specifically, the I-SC-FDM scheme exhibits a significantly lower peak-to-average power ratio (PAPR) than the original orthogonal frequency division multi-plexing (OFDM) and widely used discrete Fourier transform spread (DFTs)-OFDM schemes, thereby necessitating a much lower power gain, which is greatly beneficial for indoor power-sensitive VLC systems. Meanwhile, the implementation of an MPPC with high sensitivity enables the detection of faintly scattered light and thus fa-cilitates the possibility of omnidirectional optical transmission based on indoor NLOS links. Following this, an MPPC-based omnidirectional VLC system was developed and successfully achieved a net data rate up to 18 Mbps in a 3.6 m x 3 m x 3 m room, with a joint deployment of the I-SC-FDM scheme and hybrid time-frequency domain equalization (TFD-EQ) strategy. Such results can be viewed as an expansion of indoor VLC systems beyond line-of-sight (LOS) links and serve as a reference for the practical application of Light-Fidelity (LiFi) in future optical wireless access.