Research Of Error Correction Coding Technology For Visible Light Communication System

Visible Light Communications(VLC)is a communication which uses visible light as information carrier.It has the advantages of high rate,no electromagnetic radiation,low cost,no spectrum authentication,and high confidentiality.It is a hot research direction in the field of wireless communication in recent years.As a new type of wireless communication technology,VLC has a large communication bandwidth,can be used as a supplement to traditional wireless communication,and through the appropriate high-order modulation technology,can reach 10Gbit/s or even higher transmission speed,greatly improve the transmission efficiency.With the popularization of 5G technology and the demand for mass data communication brought by the Internet of vehicles,big data and cloud computing,visible light communication technology has broad application prospects.The existing and potential technological progress in the field of optical devices also provides strong support for the full application of visible light technology.There are currently two popular channel codes closest to Shannon’s limit:Polar and LDPC.LDPC code can be only 0.0045dB from Shannon limit,while Polar code can reach Shannon limit theoretically.However,Polar code has good performance and flexibility,and is suitable for control signaling.Compared with Polar code,LDPC code has little difference with Shannon limit,but its linear encoding and decoding complexity brings more obvious advantages.The advantage of LDPC coding in long code is more suitable for the transmission of large amounts of business data.Therefore,this paper takes LDPC code as the research object.Through the research of channel characteristics and the codec principle of LDPC channel coding,the improvement of LDPC coding to visible light channel is studied.The main work of this paper is as follows:1.Introduce the channel characteristics of visible light channel,especially underwater visible light channel,the underlying principle of LDPC,and various coding and decoding algorithms.2.Write coding algorithm based on Matlab platform,simulate the LDPC code with the best theoretical performance based on randomly generated check matrix,study the influence of various parameters on the performance of LDPC code,and select appropriate parameters to carry out the offline communication experiment under the actual visible light environment.Experimental results show that LDPC coding can reduce bit error rate effectively and improve the reliability of visible light communication system.3.Taking QC-LDPC code of IEEE 802.11n standard as an example,FPGA design of LDPC encoder and decoder is completed based on ISE platform,and the correctness of encoder design is verified by Modelsim simulation.