Research On Signal Detection And Identification In An Optical Camera Communication System

With widespread application of mobile communication technologies such as 5G,the demand for communication speed and channel capacity is increasing day by day.In order to satisfy people's pursuit of broader spectrum resources,many experts have focused on visible light communication(VLC)technology.VLC technology uses light-emitting diodes(Light Emitting Diode,LED)as a signal emission source,simultaneously realizes lighting and data communication functions,and has very rich spectrum resources.The spectrum resources of visible light are very rich and have broad application prospects.For the visible light communication system with Photo-Diode(PD)as the receiving end,the reception angle(Field of View,FOV)is narrow,it is difficult to accurately align in a mobile environment,and it is only suitable for indoor communication environments.This paper proposes an optical camera communication(OCC)system based on target detection algorithm.Firstly,this paper discusses the research status of visible light communication technology at home and abroad,compares various research focuses of optical camera communication technology,and introduces the advantages of optical camera communication system compared with the traditional visible light communication system based on PD as the receiver.Then,this paper also explores the luminous characteristics of white LEDs,and analyzes the channel characteristics of LED-based image sensor visible light communication.Several kinds of visible light modulation techniques of LED as transmitter are studied.And the introduction of multiple-input multiple-output(MIMO)technology can increase the communication capacity and greatly alleviate the influence of channel selective fading on the communication quality.In this paper,a visible light MIMO channel model is constructed to verify that simultaneous communication of multiple LEDs in MIMO channels can effectively reduce the bit error rate.Moreover,the advantages and disadvantages of photodiode and image sensor are studied carefully in this paper.In view of the background noise generated by the complex light source environment and the interference between multiple light sources on the LED array,an image sensor is used to receive the light signal.Therefore,an OCC system model suitable for outdoor visible light signal reception is designed.The OCC system designed in this paper takes the LED array on the mobile AGV(Automated Guided Vehicle)as the signal transmitting source and the CCD camera as the receiving end,which can realize the data transmission in the outdoor environment.Finally,in the experiment,the OCC system uses target detection algorithms in image processing,such as improved probabilistic Hoff transform algorithm and three-frame difference method based on adaptive threshold,to detect the location information of the LED array region in the pixel plane.In the research,the connected region method is used to identify and extract the information from the image of the target region,and the 2D data codes are output at last.It can realize relatively stable and reliable communication under mobile circumstances.The distance between the transmitter and the receiver covers 6m to14m,and the bit error rate of communication is 6.5×10^-4.