Research On Indoor Positioning Technology Based On Low Energy Bluetooth

The traditional positioning technology is mainly used in outdoor scenes,the corresponding positioning technology mainly includes the Global Positioning System, Beidou navigation position-ing system and so on.Then with the need of the society,people have proposed accurate positioning is required in indoor condition. So,the "last mile" of positioning--indoor positioning technology started to grow up.Now, there are many kinds of indoor positioning technology,including Wi Fi Positioning, Zig-Bee positioning and so on,this paper is a study of indoor positioning system based on low energy Bluetooth CC2540,the system is mainly divided into two modules, one is constructing the indoor positioning system, including the Bluetooth base station subsystem and the Bluetooth concentrator subsystem. The Bluetooth base station subsystem mainly completes the function of Bluetooth base station’s layout and positioning information transmitted to the Bluetooth Concent-rator,and the Bluetooth concentrator mainly completes the function of establishment of connection,designing of Bluetooth network and running of the algorithm. The two is realizing of the localization algorithm, the algorithm consists of two sub algorithms, one is the ranging algorithm, the other is three rings positioning algorithm.Ranging algorithm uses the method of received signal strength indicator RSSI,and to calculate the distance between two Bluetooth devices according to the RSSI and the indoor electromagnetic wave propagation loss model. The method is simple, but the disadvantage is the Bluetooth signal RSSI affected by the environment is relatively large, there are fluctuations,so this paper studies the environment factors which can affect RSSI firstly before building the model,including the air humidity, the Bluetooth nodes transmit power, other electromagnetic interference and so on,and then analyze the transmission mechanism of electromagnetic wave,finally, establish the electromagnetic wave indoor propagation loss model which is the most consistent with the actual.The positioning algorithm is the core of the positioning module,this paper proposes a weighted localization algorithm of three rings,thought of the algorith-m is that first of all, finding the nearest three Bluetooth nodes from the person to be measured according to the RSSI,and then getting three rings according to the three Bluetooth node coordinates for the center and the distance between Bluetooth nodes and measured person for the radius with the ring width for a given error,finally, get staff coordinates according to the overla-p of the three rings by using weighted polygon centroid algorithm.This paper has done the exper-iment after the theoretical analysis,the results show that this algorithm average error is about 1.6meters, and the results verify the feasibility of the algorithm.