Study On Indoor Visible Light Positioning System Based On LED Identification Technology

Nowadays,with the rapid development of science and technology,position service plays an increasingly important role in our life.The GPS(global positioning system)is well-known and widely used in the outdoor wireless positioning system.However,the architectural building blocks could seriously affect the signal transmission for the interior structure of complex indoor environment,so the GPS is not easy to apply to the indoor environment.The indoor position services and demand of people is growing in the complex indoor environment,such as shopping malls,exhibition halls,warehouses,airports and underground parking lot.The VLC(Visible Light Communication)is a new kind of wireless communication technology based on white LED light source,which can realize the normal lighting and communication function at the same time.The VLC has the characteristics of high transmission rate,high security and strong anti-interference,so,the presence of visible light communication technology can bring lots of breakthrough and innovation in the field of technology.Using VLC technology in the indoor position has the advantages of low complexity and strong anti-interference and high positioning accuracy compared with other wireless indoor positioning technology.So,the VLC technology based on the LED applied in the field of indoor positioning is regarded to be a good choice.The LED indoor VLC positioning system based on identification method is designed and realized in this academic dissertation.When the positioning system is built,the lighting effects of interior space and the stability of the transmission are considered,and then realize the indoor positioning function.To achieve the optimal effect of illumination and communication,the interior space model and light layout scheme are designed,and the relationship of the LED light source spacing and the illumination uniformity is provided.The indoor VLC channel model,influence of the received power with the light source spacing and maximum acceptable perspective are analyzed.The Fresnel lens which apply to the VLC system is proposed in order to improve the condenser efficiency.Finally the VLC system is seted up.The Stm32 processor is used as the main controller of the positioning system,and a kind of coding protocol is designed.The characteristics and driving circuits of LED light sources are tested at the transmitter,which can guarantee the basic lighting and communication.Then the current position information is loaded on the LED light sources,with the method of time division multiplexing sending information in the space.The information is transmitted to the mobile terminal by wireless link.With the photoelectric detector moving in the different position,the system determine a target range by analyzing the position information of the LED lights.Because each lamp's energy loss is not the same,they convert the voltage value is also different.The system estimates the target position according to the intensity of the electrical signal value.The receiver uses C#language to compile the software of the host computer in order to realize the function of mapping and real-time updating of the mobile terminal's position.Finally,the VLC positioning system based on identification positioning method is achieved.