Bandwidth-efficient visible light communication system based on faster-than-Nyquist pre-coded CAP modulation

摘要

With the rapid development of the light-emitting diode (LED) industry, interest in visible light communication (VLC) is growing. The limited bandwidth of commercial LEDs is one of the main challenges to achieve high-speed VLC. In this Letter, a kind of bandwidth-efficient VLC system based on carrierless amplitude and phase (CAP) modulation is proposed, where a simple differential faster-than-Nyquist (FTN) pre-coding scheme is employed to compress the spectrum and further improve the overall system baud rate. The system is experimentally demonstrated with a data rate of 1.47-Gb/s over 1.5 m free space transmission. The results indicate that an improvement of 80 Mbaud is achieved by FTN-CAP4 at 20% subband overlap and 40 Mbaud rate improvement by FTN-CAP16 at 7.5% subband overlap. Compared with traditional CAP, the FTN pre-coded CAP shows a better performance in spectral efficiency (SE) and intercarrier interference resistance. To the best of our knowledge, it is the first time to employ FTN pre-coded CAP in indoor high-data-rate VLC systems.