Research On Performance Of Visible Light Communication System

With the development of the times,the growing demand for communication leads to a growing shortage of wireless spectrum resources.Visible light communication(VLC)technology using visible light to achieve communication,which has a great help to solve this problem,has become a hot spot of research.How to improve the performance of VLC system,and apply the technology in practice have become one of the main research directions of VLC.In this paper,according to the principle and working characteristics of Light Emitting Diode(LED),a kind of driving circuit of LED is proposed.Photodiode is used in receiver to get the signal light.At the same time,the pre-emphasis circuit is used to improve the system.Finally,the system can transmit 7 MHz square wave when the distance of transmitter and receiver is 2.5 m.The indoor visible light communication channel model is simulated in this paper.According to the algorithm proposed by Henrik Schulze,the frequency response of non-line-of-sight(NLOS)links and line-of-sight(LOS)link of visible light communication channel with are calculated respectively.The channel frequency response of Single-Input Single-Output(SISO)and Multi-Input Single-Output(MISO)indoor visible light communication systems are compared and analyzed.In addition,the received optical power distribution,signal-to-noise ratio,channel capacity and spectral efficiency of the system are studied and analyzed respectively under the condition of the same total transmit power,using SISO and MISO technologies respectively.For the MISO system,the pre-coding is used to improve the SNR and other characteristics.Finally,the principles of channel estimation for obtaining channel characteristics and the principles of compressive sensing for signal compression sampling are studied.Channel estimation based on compressive sensing is proposed for MISO indoor VLC channel.The feasibility of the scheme is verified by simulation.