Research On White Light Visible Light Communication System Based On Diffuse Reflection

As a supplement to RF,visible light communication(VLC)has become the focus of studying for the past few years because of its rich spectrum resources without authorization.However,the research on indoor visible light communication is mainly focused on point-to-point direct link,while the practical application value of diffuse link is ignored.As a supplement to direct link communication,diffuse link can effectively expand the communication range of direct link based wireless optical communication,enhance the performance of communication system,and expand their range of applications.In this dissertation,the influence of diffuse reflection on communication performance is studied from two aspects of experiment and simulation.Firstly,by simulating the power and signal noise ratio(SNR)distribution in the plane,the distribution of diffuse reflection signal and the conclusion that using diffuse reflection signal can improve the communication performance in the plane are obtained.After that,a communication experiment model with the same size as the simulation model is built.The distribution of the diffuse reflected signal is studied by measuring the intensity of the diffuse reflected signal at different positions,and it is found that the distribution of the diffuse reflected signal is consistent with the simulation.In order to explore the diffuse reflection effect on the performance of communication,bit error rate(BER)measurement system is designed.Based on the statistical measurements of the BER in a two dimensional plane,a method to improve the communication performance and expand the communication range is explored.The results show that the BER at the corner of the space can be increased from 100% to 35%,and the communication distance can be increased by about 7 cm lengthwise,accounting for 5% of the total length and 6 2 cm in transverse direction,accounting for 7% of the total length.On this basis,the feasibility of the application of diffuse reflection signal in practical environment is further studied.The experiment based on white light VLC relied on diffuse reflection is carried out in the corridor.By completely blocking the direct link,the diffuse link can still communicate in a certain range.The experimental results provide a solution to such problems as signal interruption caused by direct link blocking or shadowing during the communication process in VLC or poor communication performance due to weak optical signal in some region inside the room.