Design And Realization Of Indoor High Speed And High Density Visible Light Communication System

Along with the popularization of Wi-Fi technologies and increasing demand for high reliable Wi-Fi service,the problems of limited spectrum bandwidth and insufficient capacity in Wi-Fi network becomes more serious.Especially in major public places such as railway station,airport,mall and so on,it is a kind of luxury to implement the high-speed internet access in Wi-Fi network.In view of the above questions,a new high-speed high-density indoor visible light communication(VLC)system is proposed with the network integration.Based on the ubiquity of LED and distinct space division ofVLC,the systemenables both the low-power Wi-Fi network access and illumination purpose.It is aimed at overcoming the insufficient capacity and enhancing the user experience by supporting high-speed access within 3 meters of each LED in major public places.This paper analyzes the density capacity of high-speed high-density VLC and proposes the modulation of SC-PPM for the system.Additionally,we design and implement ahigh-speed high-density system with the power line integration.Our main research is summarized as follows:Firstly,aiming at the problems of the limited spectrum bandwidth and insufficient capacity,a new high-speed high-density VLC system is proposed.By comparing the access capacity in two different systems under indoor environments,the theoretical analysis indicate our proposed system achieves higher access capacity than Wi-Fi network for a large number of terminal access.Secondly,we gave a deep analysis of the impact factor related to the density capacity of VLC.In order to reduce the interference between Table-fi,we build adensity capacityanalysis model for the indoors high-speed high density VLC systems,by studying the relations between the transmitting power of Table-fi and capacity.Furthermore,we make extensive simulations to analyze the relations among the performance of our system,the power and number of Table-fi,the number of users and the room area.The result of systems simulation proves the practicability of high capacity by reducing power of Table-fi.To further enhance the system capacity,we put forward three backbone network integration access schemes,of which the access capacity isanalyzed in detail.Thirdly,in accordance with differentpractical demand,we designed an energy efficient modulation method,SC-PPM.A comprehensive analysis about the BER(Bit Error Rate)of SC-PPM in channels underGaussion white noise is given.Additionally,we built the LED output power optimal model which simulates the output efficiency with meeting the given lighting level.Simulation results show that SC-PPM is a more energy efficient modulation method,whichobtains less powerful output compared with conventional PPM.Finally,we design and implement a high-speed high-density VLC system based on the power line integration.The block diagram,the implementation scheme for each module's functionand experiment results are given in the paper.There are two kinds of experiment:the functional test and the performance test.The functional test verifies the system requirement of high-speed high-density VLC,including the peak transmitting rate,coverage area and frequency response characteristic of EOE channel.Furthermore,the performance test compares the high-speed high-density VLC and Wi-Fi with a variable number of terminations in detail.Simulation results show that our proposed system achieves higher capacity than Wi-Fi under these conditions.