Research On Visible Light Communication System Combining Display And Communication

Visible light communication(VLC)attracts extensive attention and research recently.Light emitting diodes(LEDs)have many advantages such as high electro-optical conversion efficiency and large modulation bandwidth.They are ideal light sources for VLC.The VLC technology using optical cameras as receivers is called optical camera communication(OCC).Optical cameras are applied on a large scale nowadays,which is beneficial to the popularization of OCC and has broad application prospects.The combination of OCC and existing optical display system makes the display system integrate the communication ability,which has higher application value.But there are still many problems that need to be addressed.This paper studies the VLC system combining display and communication.According to the type of signal transmitter,it is divided into LED backlight signal transmitter and LED display array signal transmitter.The main research contents are as follows:Starting from the photoelectric characteristics of LEDs and image sensors,a theoretical model of the optical camera communication system is established and simulated.Research in the possibility of using color shift keying(CSK)for this system.The results show that 8-CSK can bring about three times the modulation efficiency of the on-off keying.The optical camera communication system has bit error characteristics similar to traditional radio frequency communication.LED backlight is used as the signal transmitter.Using the camera's rolling shutter effect to receive the signal.Cooperate with the liquid crystal display module to realize the combination of communication and display.A unique frame structure is designed for clock restoration and maximum likelihood decoding.Use 8-CSK and beacon joint packet reconstruction to achieve a data rate much higher than the frame rate of the camera,which is about 20 kbps.The bit error rate meets the requirement of 7% forward error correction code.LED array is used as the signal transmitter.Camera's approximate global shutter is used to receive the signal.Frame insertion is proposed to realize the combination of display and communication.Use 8-CSK to improve modulation efficiency.The k-means method is used to identify the LED array's position,and the k-means++ and Gaussian mixture model clustering algorithm are used to demodulate the signal.A data rate of 2.88 kbps is achieved at a 4x4 array scale.The bit error rate meets the requirement of 7% forward error correction code.