Design And Implementation Of Optical Camera Communication System Based On Smartphone

Visible light communication technology based on LED light sources,as a rapidly developing emerging wireless communication method,has the characteristics of frequency bandwidth,green security,good confidentiality and strong,anti-interference ability.It has been widely concerned because it can effectively solve the crisis of radio frequency spectrum resources.Optical camera communication(OCC)technology is a branch of visible light communication technology.While inheriting its advantages,by using the built-in camera of the smartphone as the receiver of the system,the cost and complexity of the OCC system can be significantly reduced,and the operation convenience of the OCC system is enhanced at the same time.It has good application prospects in indoor positioning,Internet of Things and smart home.This paper firstly proposes a design scheme for the optical camera communication system based on RGB-LED,which aims to improve the information transmission rate of the optical camera communication system.This scheme used RGB-LED as the system transmitter,which can effectively improve the system information transmission rate through wavelength division multiplexing.This scheme uses the built-in camera of the Android smartphone as the system receiver,and uses the rolling shutter working characteristics of the camera of the mobile phone to receive the information.For information receiving and decoding,an Android APP that can run independently based on Java language is designed.The reliability of information transmission is effectively improved by introducing algorithms such as histogram equalization and least squares fitting,and the proposed blooming effect suppression scheme and synchronous dynamic compensation scheme effectively reduces the bit error rate of the system.Experiments verify that the proposed scheme can achieve information transmission with a transmission rate of 21.6 kbps on an Android smartphone.Secondly,for the problem of limited information transmission capacity of the optical camera communication system,a multi-frame image processing scheme based on JPEG and a multi-frame image processing scheme based on GIF are proposed.In this paper,when obtaining a video carrying long text information,different video preprocessing methods are adopted for the two schemes.After separating the video image and information decoding frame by frame,both schemes can achieve the reception of long text information.By comparing and analyzing the two schemes in one software program,the experiment shows that the multi-frame image processing scheme based on JPEG is better than the multi-frame image processing scheme based on GIF,which can effectively improve the information transmission capacity of the system.At last,based on the designed and implemented optical camera communication system,this paper designs an indoor user service system based on OCC-WiFi dual link.The system consists of three modules:LED light source node,smartphone terminal and central control server.The LED light source node and the smartphone terminal communicate through the OCC link as a downlink data link to transmit indoor positioning information and related product information.The smartphone terminal and the central control server communicate through the WiFi link as an uplink data link to deliver the user's shopping guide service request.Finally,a functional test of the system was carried out by constructing a system model.Experiments show that the system has practicability and reliability.