Research On Color Shift Keying Modulation Technology In Visible Light Communication

Visible light communication technology is a communication method that uses visible light as a carrier to transmit information and directly transmits optical signals in a wireless channel.For traditional communication technology,spectrum is a limited resource,the use of each spectrum is strictly controlled,and visible light communication does not require the approval of relevant agencies to be used directly,so visible light communication can be used in a wider range.Color shift keying modulation technology is a modulation method in visible light communication technology,this modulation method uses different colors in visible light to transmit data,compared to other modulation methods,the transmission rate is higher,and the luminous intensity is stable,and there is no flicker problem.This thesis studies the constellation design and coding design of color-shift keying modulation to improve the transmission reliability of visible light systems.(1)First of all,a detailed study of modulation technology in visible light communication is carried out;secondly,a multi-intensity constellation design scheme is proposed,based on the triangular division of the constellation chart,the constellation points are divided into sets,mapped to different intensity planes,and the intensity surface size is calculated according to the minimum European distance on different intensity surfaces;finally,under the condition of target color constraint,the triangular division constellation points on different intensity surfaces are screened to obtain a constellation chart with a number of quadratic powers,and the conditions of equal minimum European distance on different intensity surfaces are equal.The coordinates of the constellation points are calculated,and the constellation points are finally mapped one by one with the binary code group.Experimental results show that compared with the existing basic constellations,spherical constellations and bilayer constellations,the multi-intensity constellation design scheme has a gain effect of 0.8-3.4d B under different transmission rates.(2)First,the basic principles of finite state machine are studied in depth;secondly,the non-two-power constellation scheme designed in(1)is combined with the finite state machine to divide the constellation points into different sets,and the colorshift keyed modulation coding scheme of high-performance gain is designed;then,each state in the finite state machine is divided into two sub-states,the state transfer diagram of the finite state machine is redesigned,and the designed coding scheme is applied to the plane constellation for simulation;finally,the simulation experiment is carried out.Experimental results show that compared with the trigonometric mesh code modulation scheme and the multi-intensity constellation scheme,the newly proposed three schemes have a gain of 0.5d B,2.4d B and 3.3d B at a transmission rate of 2bits/symbol,and a gain of 1.4d B,2.2d B and 3.0d B respectively at the 3bits/symbol transmission rate.