Research On The Visible Light Communication System Based On The Indoor Point Of White LED

In this era of information explosion,with the rapid progress of modern science and technology,having insecurity of information,lack of spectrum resources,electromagnetic interference and other problems,wireless communication network can't meet the demands of human life.Visible Light Communication which could illuminate and communicate in the same time,is a new type of wireless communication network with green initiative.Because of easy to installation and use,fast communication speed and so on,Visible Light Communication has arouse attention of global researchers,and get a lot of research result.White LED is used as light source in Visible Light Communication system.The signal is coded and modulated by the processing unit and converted into the electric signal,which is transmitted to the light source to form the optical signal.The optical signal is received by the photodetector at the receiving terminal after transmitting in free space and then converted into the electric signal by demodulation and decoding.Thus the transmission of the signal is completed.This paper focuses on the establishment of indoor point-to-point visible light communication system based on white LED and the simulation analysis of OFDM technology.(1)Aiming at visible Light communication system still stay in theoreticalanalysis and basing on indoor visible light communication scheme with white LED,this paper designs a VLC system which could transmit the character and audio in time.The system selects simplex communication with same time and frequency,STM32 to control in transmitting and receiving,PWM modulation technique which possess superior anti-jam capabilities and easy to realize in modulation-demodulation.At last we test and verified the feasibility of this system,and the results indicate that the system can communicate distance could reach 3m and the rate could up to 200 Kbps.(2)For solving the practical problems that multipath effect caused by dispersion of light source and enhance the communication performance,this paper lucubrates the OFDM modulation technology in VLC,and use MATLAB to simulate and verify.It shows that QAM/PSK,the subcarrier,add encoding way according to specific channel situation,which could decrease the error rate.It provides theoretical support when VLC system come into real life.