Implementation And Performance Analysis Of Optical Camera Communication System Based On MIMO

Radio Frequency(RF)-based wireless communication spectrum resources are scarce.Therefore,Optical Wireless Communication(OWC)technology using light waves as a communication medium has been widely studied by scholars at home and abroad.OWC includes free space optical communication and Visible Light Communication(VLC).Optical Camera Communication(OCC)is a VLC technology that uses a camera as a receiving device,which has the advantages of no spectrum certification and low energy consumption.It can be used as a complementary technology of RF,providing effective solutions to the limitations of RF spectrum resource scarcity and strict supervision in wireless network deployment.Therefore,the OCC technology has attracted the attention of domestic and foreign researchers since its proposal,and has huge application potential in the fields of intelligent transportation systems and indoor positioning.Although OCC has many advantages,there are still some shortcomings: The complex image processing technology at the receiving end of the system will seriously affect the performance of the system,resulting in high end-to-end delay of the system;In the Vehicle to Vehicle communication(V2V)scenario,a low frame rate vehicle-mounted camera will limit the system transmission rate.In this paper,a low frame rate vehicle-mounted camera is used as the receiving device,and narrow-band filtering technology is used to reduce the impact of optical noise,reduce the difficulty of image processing from the physical level,and reduce the image processing delay;Introduce Multiple Input Multiple Output(MIMO)technology into the OCC system to increase the system transmission rate.The main work and contributions of this paper are as follows:(1)Research on decoding technology of OCC system based on MIMOFor the OCC system where the emitting device is a specific wavelength LED array,the decoding algorithms based on traditional image processing methods are analyzed: LED array decoding algorithm based on Hough circle transform,LED array decoding algorithm based on connected domain markers,and LED array decoding algorithm based on directional projection method.Using Matlab simulation platform to draw Gaussian beam light field image to simulate the imaging effect of the LED array at the receiving end,comprehensively considering the OCC system delay and bit error rate,the performance of the above decoding algorithms was compared and analyzed.The simulation results show that the LED array decoding algorithm based on the directional projection method can achieve smaller processing delay and bit error rate than the other two algorithms.This paper selects it as the decoding algorithm for the MIMO-based OCC system.(2)Implementation of OCC system based on MIMODesign the overall structure of the OCC system based on MIMO,and complete the design of the functional modules of the OCC system transmitter and receiver.The808 nm LED array is used to send the signal,and the narrow-band filter camera receives the signal to complete the selection and circuit realization of the corresponding equipment of the OCC system.Realize the OCC system based on MIMO and complete the real-time transmission of information.The communication performance of the proposed OCC system based on MIMO is tested.The experimental results show that: when the receiving end of the system is a 25 fps vehicle-mounted camera,when the 4×4 LED array at the transmitting end flashes at a frequency of 12 Hz,the transmission rate can reach up to 126.32bps;the transceiver end of the system tests the system performance by transmitting 30 kb data every 0.5m,in the experiment,the system has no errors within the communication distance of5.5m.In this paper,the OCC experimental system is built under the condition that the receiving end of the system is a vehicle-mounted camera with a low frame rate and a short focal length.The relationship between the communication distance of the system and the bit error rate was tested,which laid the foundation for the subsequent optimization and improvement of the system and its application in practical scenarios such as V2V.