Bidirectional Visible Light Communication System Based On RGB-LED Transceiver

Visible light communication is an environment protecting,high confidentiality communication technology without electromagnetic interference,which attracts more and more attention.The primary researchesof visible light communication system focus on one-way visible light link at present,visible light communication is used for downlink while radio frequency is mainly used for uplink.However,the main challenge of Visible light communication system iselectromagnetic interference.In our work,RGB-LED was usedas transmitter to communicate without electromagnetic interferencein bidirectional visible light communication system.It has important research significance to avoid the communication of electromagnetic interference place.In this paper,RGB-LED are used as visible light communication receiver photodetectors.Through the simulation of the quantum efficiency,responsivity,and frequency response of the red,green,and blue bands,the optoelectronic characteristics of the corresponding bands are obtained.Using the optoelectronic characteristics of RGB-LED,the bidirectionalvisible light communication system using RGB-LED at both the transmitter and the receiver was designed.By analyzing the influence of sight and outsight distance transmission,outdoor atmospheric turbulence on channel,the model ofvisible light communication system with indoor and outdoor channels are analyzed and built.We designed bidirectional visible light communication system based on time and color according to photoelectriccharacteristics of RGB-LED.Compare the reliability and spectral efficiency of the two systems.The innovations in thispaper are as follows:1.We adopted RGB-LED as photoelectric detection device to receive visible light communication system and analyzed its electro photoelectric performance.By analyzing the photoelectricperformance of RGB-LED,red LED has the best photoelectric performances,which the quantum efficiency of red,green and blue LEDs can reach 51.09%,36.9%,47.4% respectively,the peak of response degree is 0.248 A/W,0.129 A/W,0.159 A/W;-3dB bandwidth is 3.51 MHz,0.49 MHz,1MHz respectively.The results show that RGB-LED has a certain wavelength selection function as a photoelectric detector.2.We designed bidirectional visible light communication system based on time and color.By comparing the reliability and spectral efficiency between systems,we can find that bidirectional system distinguished by time is a good choice if the request of communication rate is not high;bidirectional system distinguished by color can meet high requirement of communication rate.3.The influence of atmospheric turbulence on communication performance of outdoor visible light communication should be considered.The mutual interference cost parameter is defined to measure the influence of mutual interference between the uplink and the downlink in the bidirectional visible light communication system.Simulation analysis using 4-PPM modulation indoor color bidirectional communication system,in the 100 Mbps transmission rate,the maximum reliable transmission distance of uplink and downlink are 3.75 m and 4.21 m respectively;when the transmission distance is 2.5m,the maximum reliable transmission rate of the system is 225 Mbps.