Design And Implementation Of VLC-based Multidimensional Positioning System

In recent years,location based service(LBS)has experienced tremendous development.Especially,the demand for indoor positioning is increasing.In the meantime,visible light communication(VLC)is also under a great speed of developing,and it is becoming an important complementation for wireless communication technologies like Wi-Fi or cellular communication.Indoor positioning is one of the important applications of VLC.It can take full advantages of existed illumination facilities and achieve high positioning accuracy,which provides a great improvement for the quality of indoor LBS.This thesis focuses on the key problem about how to utlize VLC in multi-dimensional positioning system,deeply studies the implementation of pratical positioning system and multi-dimensional positioning algorithm,and realizes the goal of precise multi-dimensional positioning.The main work of this thesis is as follows:(1)The development of positioning and light emitting diode(LED)illumination technology is introduced.Then,the existing research of positioning technology based on VLC is discussed.The characteristics and application prospect of multi-dimensional positioning are analyzed.(2)By comparing with existed indoor positioning technologies,the relative advantages of VLC-based positioning are described.The feasibility of using common wireless positioning methods in the VLC-based positioning system is discussed.Finally,a simple reconstructing scheme for existed illumination facilities and the overall implementation sheme of VLC-based positioning system are given.(3)A specific implementation scheme of VLC-based positioning system is proposed.By analyzing characteristics of VLC and requirements of positioning applications,the baseband of VLC is designed and implemented including modulation,demodulation,coder,decoder and frame struct of visible light signals.The implementation of transmitters and receivers are given.In the meantime,the software platform is established in the positioning server to configure and test the whole positioning system.The positioning graphical user interface(GUI)program based on Qt is implemented.(4)Two three-dimensional positioning algorithm based on trilateration,fingerprinting and K-nearest-neigbors are proposed.By simplifying and fitting the distribution function of received signal strength(RSS),the trilateration-based algorithm utilizes equations of trilateration to obtain final positioning result.The positioning algorithm based on fingerprinting and K-nearest-neigbors firstly utilizes fingerprinting to find the nearest neighbor,then uses K-nearest-neigbors' iteration searching to obtain K-nearest neighbors.The positioning result is given by using the weighted average of K-nearest neighbors.(5)The configuration and test of VLC-based positioning sytem are described.Positioning results and analyses of both two three-dimensional positioning algorithm based on trilateration,fingerprinting and K-nearest-neigbors are given.It can be seen that trilateration-based algorithm achieves the better positioning accuracy in most parts.However,the positioning algorithm based on fingeiprinting and K-nearest-neigbors utilizes fingerprinting to strengthen its feasibility,and it also utilizes K-nearest-neigbors' iteration searching and weighted average of location to improve positioning accuracy at the same sampling density.(6)Main research work of this thesis is summarized,and shortages of current researches and direction of future research are given.