Research On Polar Codes And Its Encoding And Decoding Technology For Visible Light Communication

Among all the wireless communication technologies,visible light communication?VLC?technology that can provide effective illumination and communication simultaneously is one of the most promising technologies.Compared with traditional radio communication,VLC technology,which ordinarily means a kind of technology use LED as source,visible light as information carrier and free space as transmission medium,has the advantages of environment protection,high transmission rate,high security,rich spectrum resources and wide application scenarios.After the unremitting efforts of researchers,the VLC technology has made a rapid progress in the past ten years.There Eare various channel codes being used in VLC system in order to improve the performance of communication system.However,polar codes which is burgeoning and the first error-correcting codes with an explicit construction that can provably achieve Shannon's channel capacity is little studied in VLC research field.Based on the National Natural Science Foundation of China?NSFC?,this thesis mainly focus on the channel model of indoor VLC system and the performance of polar codes used in this system by simulation and experiment.The main work and innovation points of thesis are as follows:Firstly,the basic principle and structure of indoor VLC system was introduced.By the modeling analysis of indoor light of sight?LOS?VLC channel,completed the simulation of the distribution of channel impulse response in the room.Meanwhile,the proposed model was verified by the simulation of basic OOK modulation.Secondly,a LOS VLC system scheme based on polar code and a method for estimating polarized channel reliability with the help of Gaussian approximation were proposed.By designing a simulation scheme,the performance of polar codes was verified by simulation experiment.The results showed that the polar codes have great BER performance,and the error control performance can be obviously improved by different coding or decode method and different key parameters.Thirdly,an indoor VLC experimental platform was proposed and implemented.Then the performance of polar codes used in indoor VLC had been verified by off-line experiments for the first time.The experimental results showed that,for indoor LOS VLC,the polar codes can effectively enhance communication performance,and polar codes has better error control performance than LDPC.Based on 10^-3 bit error rate,in comparison with an uncoded system,effective communication distance can reach 200 percent in polar coding system with 1024 code length and 0.5 code rate.