Research Of Improved M-4B5B Coding In Visible Light Communication And Implementation With FPGA

Nowadays,due to development of semiconductor technology and increasing consideration about environment conservation,LED lights which can preserve the environment are widely used.The technology of visible light communication using LED lights is also gradually improved.Widespread usages of LED does not require any other routers.Visible light communication must be satisfied with the function of illumination,and then serves as the function of communication.As a function of illumination,a stable brightness should be provided to users.However,there are two things that must be solved,blinking and dimming.Blinking is harmful to people's eyes,even to mental health.For the basic function of illumination,flicker must be resolved.Therefore,we need to solve the flicker phenomenon,and this to pic will introduce the Improved M-4B5 B code to solve the flicker phenomenon.Improved M-4B5 B code a bit differs from 4B5 B code.The principle of 4B5 B is that 4 bit binary numbers are represented by binary numbers of 5 bit.The ratio of "0" and "1" will cause flicker that M-4B5 B code is chosen by 3:2 or 2:3 ratio of “0” and “1” in 32 bits.Thus,the average brightness is always 60%(3:2)or 40%(2:3).In a word,the difference of average brightness of M-4B5 B encoding is smaller than the difference of average brightness of the 4B5 B encoding.This project aims to(1)implement using FPGA to represent visible light communication(2)to compare between existing code and improved M-4B5 B code.It is not only completing the whole visible light communication system but also analyzing the efficiency of coding.This project mainly completes a visible light communication system which is divided into two parts: the former part is LED Driver and Photo-Diode Driver that the most important part is visible light communication.LED lighting transmits data,and Photo-Diode receives data.The latter part is FPGA,including the encoding part.Functions include encoding,decoding,AD conversion,time synchronization,M-4B5 B based signal detection,decision,and bit error rate calculation,etc.The main content of the work is(1)introducing improved M-4B5 B code(2)programming improved M-4B5 B code by using Verilog HDL(3)designing visible light communication system(4)verifying Driver LED and Photo-Diode Driver.It is to verify the satisfaction of basic requirements of the visible light communication system in this paper and to observe the waveform of high-speed communication in visible light communication.(5)Verification of visible light communication transceiver module wired communication,before verification of transceiver module,the communication performance of the visible light communication module is confirmed by the single wire based wire.(6)Verification of integrated transceiver module and the whole visible light communication system,(7)analysis of the improved M-4B5 B coding methods.(8)The improved M-4B5 B coding is compared with the existing encoding methods.