Research On Indoor Positioning Technology Based On Visible Light Communication

In recent years,with the advent of the LED green lighting era,Visible Light Communication(VLC)has been rapidly developed due to its advantages of energy conservation,environmental friendliness,flexible mobility and high safety.Meanwhile,indoor positioning technology based on VLC has received widespread attention.The use of the LED lamps enables high positioning accuracy under the existing lighting facilities,thereby improving the quality of indoor location services,and providing new possibilities for indoor positioning technology.There are some problems to be solved in the research of indoor positioning technology based on visible light:there are few studies about the influence of environmental factors on the positioning accuracy,and there is a lack of solutions for visible light positioning application.In view of the above problems,this paper studies the indoor positioning system with noise interference,multiple reflection and obstacle occlusion,and gives the optimization scheme to improve the positioning accuracy.The indoor positioning scheme based on visible light communication and Android smartphone is realized.This paper is organized as follows:First of all,the channel model of indoor visible light communication system is studied.In order to solve the tedious recursion process of traditional reflective link model,Independent Reflecting Element Interaction Characterization(IREIC)model is adopted to reduce the complexity of calculation.some important performance indicators are simulated Under the indoor model with 5m × 5m × 3m,including illumination intensity,received optical power,channel impulse response and signal-to-noise ratio.Secondly,the commonly used localization algorithms for indoor visible light positioning system are studied,including the Time of Arrival(TOA),Time Difference of Arrival(TDOA),Angle of Arrival(AOA),Received Signal Strength Indicator(RSSI).Based on the channel model that established in this paper,theoretical principles of these algorithms are analyzed.Simulation results show that the performance of RSSI algorithm in positioning accuracy and complexity both are Better than TOA,TDOA and AOA.Then,based on the particularity of the indoor environment,the characteristics of LED visible light communication and the RSSI positioning algorithm,some interference factors which affect the performance of indoor visible light positioning system are investigated,including noise interference,human walking or obstacle blocking interference and multiple reflection interference.In view of the influence of noise interference,a scheme of Kalman filter is proposed to eliminate the noise signal components in the received signal as much as possible.The simulation results show that the scheme improves the positioning accuracy by 23%.Aiming at the obstruction caused by human walking or obstacles on the transmitted visible light signals,an adaptive correction scheme is adopted to restore and correct the missing channel state information.By using the adaptive correction scheme,the performance of the indoor positioning system has been greatly improved,and the average positioning error is reduced from 0.33m to 0.25m.In view of the influence of multiple reflections,a nonlinear optimization scheme is proposed,which improves the positioning accuracy by 30%when compared with linear least squares estimation.In order to further improve the performance of positioning system,a strong signal selection optimization scheme is proposed,weighted centroid algorithm is introduced and combined with strong signal selection(SSS/WG),The results show that the SSS/WC can effectively reduce the impact of reflection on the positioning system and reduce the positioning error to 0.35m.Finally,an indoor positioning scheme based on visible light communication and smart phone is proposed.Taking full advantage of the features of smart phone's built-in light sensor,The positioning accuracy of the system in 4.5m×3.8 m room can reach to 0.42m.