Research And Implementation Of Indoor Location Based On Low Power Bluetooth

With the rapid development of social economy and the improvement of people's cultural living standard,people's demand for indoor location information is more and more urgent.For example,large shopping centers,underground parking lots,airports,museums,exhibition halls and so on all need the location information of indoor personnel and goods.At present,the mainstream satellite positioning system mainly used in outdoor scene,its satellite signal can not penetrate the building,and in the indoor environment,due to the presence of obstructions,the satellite signal can produce refraction,reflection and attenuation,resulting in inaccurate positioning or even unable to locate.In recent years,indoor positioning technology has developed rapidly,mainly including ZigBee,ultrasonic,RFID,ultra wideband,WiFi,Bluetooth,geomagnetic,infrared technology and so on.According to the domestic and foreign research on indoor positioning for many years,after comparing the accuracy,cost and other factors of these positioning technologies,the low-power Bluetooth indoor positioning technology is finally decided as the research direction.Firstly,according to the free space propagation model of Bluetooth signal,the principle of wireless circuit path transmission is studied and analyzed,and the logarithmic path loss model of Bluetooth signal is selected as the fitting model in this paper.Using this model,the median and Gaussian mixture filter is used to process the abnormal value of the received Bluetooth signal strength,which effectively removes the signal singular value,and makes the logarithmic path loss model fitted by the least square fit more in line with the Bluetooth signal attenuation process in the experimental environment.Secondly,aiming at the shortcomings of the traditional least square algorithm for trilateral localization,a least square iterative algorithm based on Taylor series linearization is proposed.The algorithm measures the distance from the target to each Bluetooth base station through the Bluetooth signal path attenuation model,and calculates the coordinates to be located by establishing more than three distance equations and using the least square iterative algorithm based on Taylor series linearization.Experimental results show that the proposed algorithm can effectively improve the accuracy of Bluetooth indoor positioning.Finally,based on the technology design of low-power Bluetooth 4.0,this paper designs and implements the elderly indoor fall monitoring system and subway emergency communication system based on low-power Bluetooth positioning,and carries out the experimental verification respectively,and the experimental results show that the system meets the application requirements.