Pulse And OFDM Hybrid Modulation Of High-speed Visible Light Communication

LED with its high efficiency, low power consumption, fast response and long life has become a new generation of lighting technology, and gradually used in office buildings and home and other places. LED visible light communications is emerging as an information transmission medium of short-range wireless communications technology. Compared with traditional wireless RF communication, visible light communication with advantages of high transmission power, high data transfer rate, harmless to body, no electromagnetic interference and is providing a new access way for data network. Meanwhile, the visible light communication may be more suitable for intelligent transport systems and hospitals and airports and other electromagnetic sensitive occasions.This article introduce the characteristics of the visible light communication systems based on white LED and introduce applications and research status and development trends, then analysis of the spectral response characteristics of white LED and the basic model of indoor visible light communication channel, sametime analysis visible light communications system use of OOK, PPM, NRZ-OOK modulation. For the features of white LED device and the existing multi-path effects in transfer, we study the influence of the key factors in the data transfer rate of modulation. On the one hand use OFDM modulation technique for VLC, we prove that it is have the same advantage in the VLC. On the other hand for more effective using the spectrum energy in single white LED and to improve transmission speed, use pulse and OFDM hybrid modulation of visible light communication, through the Simulink modeling and simulation, demonstrate the feasibility of hybird modulation, enabling higher-speed transmission.