Research On MPCSK Coding And Modulation Technology In Visible Light Communication

Visible light communication is a communication method that uses visible light as a carrier to transmit data in wireless channels.Different from traditional radio frequency communication methods,visible light communication signals use visible light spectrum and do not need to apply for frequency band license authorization.Therefore,visible light communication can effectively improve the"spectrum shortage"faced by traditional radio frequency communication.Among them,color shift keying is a commonly used modulation method in visible light communication.It uses the color characteristics of visible light to transmit data,realizes high-order modulation,higher transmission rate and constant luminous intensity,thus effectively avoiding the Intensity flickering issue.This thesis mainly studies the constellation design and coded modulation scheme of color shift keying modulation technology,aiming at improving its signal transmission quality.（1）In order to study the color shift keying modulation technology in depth,firstly,the basic principle of the color shift keying modulation technology of visible light communication and its existing improvement methods are investigated;secondly,the idea of color shift keying technology based on multi-intensity planes And related constraints propose a design scheme based on the midline division of the color shift keying constellation,and based on the constellation scheme of the three-dimensional signal space designed by this design scheme,the constellation number in the three-dimensional signal space is proposed scheme,and simulated and analyzed it;then,introduced a finite state machine and proposed a joint coding and modulation design scheme based on midline division color shift keying under the minimum number of states,through subset division,constructing a finite state machine and solving The optimal constellation coordinates of the three-dimensional signal space and other steps design three joint coding and modulation schemes under different code rates,and compare and analyze the simulation results with the existing schemes.Finally,the results show that:compared with the existing traditional schemes and improved schemes under three different code rates,the constellation scheme whose number of constellations is an integer power of two improves about 4.6d B when the bit error rate is 10^-6;The proposed joint coding and modulation scheme based on centerline partition color shift keying increases the minimum Euclidean distance and improves about 3.9d B when the bit error rate is 10^-6.（2）In order to further improve the quality of signal transmission and improve the reliability of signal transmission,the joint coding and modulation scheme based on midline division color shift keying is improved.Constellation structure and optimal coordinates to increase the minimum Euclidean distance between constellation points,an enhanced joint coding and modulation design scheme based on midline division color shift keying is proposed,three code rate schemes are given and It is verified and analyzed by simulation;then,the bit error rate performance of the proposed scheme is further improved by adding forward error correction codes in the coding and modulation scheme,and a recursive systematic convolutional code is introduced as the forward error correction code used in the scheme.Wrong code;Finally,the two improved schemes are simulated,and the results show that,compared with the existing scheme and the scheme before improvement,the enhanced joint coding modulation scheme based on center line division color shift keying increases the minimum Euclidean distance And when the bit error rate is 10^-6,the highest improvement is about5.6d B;after adding the forward error correction code,the proposed joint coding scheme still has the advantage in performance.