Research On Key Technologies Of Smart Phone Collaborative Indoor Positioning

With the needs of social development,indoor positioning has become an important problem to be solved urgently by researchers.Realizing accurate,reliable,real-time and universal indoor positioning to meet the needs of the mass market has important scientific significance and social application value.With the continuous improvement in the richness and quality of sensors on smart phones,smart phones have become more and more capable of sensing the environment.At the same time,people have become accustomed to acquiring location information through smart phones.Developing indoor location technology based on smart phones has unique advantages.Unlike most researchers who study indoor positioning technology based on a single positioning terminal or a single positioning algorithm,the breakthrough point of this paper is to focus on the research of smart phone cooperative indoor positioning technology in which multiple positioning terminals cooperate with each other and multiple positioning algorithms fuse with each other.The main work and achievements of this paper are as follows:(1)The influencing factors of Bluetooth 4.0/5.0 RSSI are analyzed and the corresponding processing strategies are given.The Bluetooth RSSI between different types of terminals is statistically analyzed.It is found that the Bluetooth antenna gain has directional difference.Besides the influence of environment,the observed Bluetooth RSSI is also related to the hardware equipment at the receiving terminal and the transmitting terminal.These factors must be considered in positioning calculation.However,Bluetooth signals between different types of terminals have similar propagation laws,which provides support for adopting the same type of propagation attenuation model.Based on the above factors,this paper compares and analyzes two common wireless signal propagation models with measured data,and selects a suitable Bluetooth signal propagation attenuation model to quantify distances between different types of terminals using Bluetooth RSSI observation values,thus completing the calibration of cooperative measurements between terminals.(2)In order to solve the problems of low indoor positioning accuracy and low reliability of single terminal,this paper proposes an peer-to-peer cooperative positioning algorithm that comprehensively utilizes the fingerprinting positioning results of single terminals and the distances information between terminals for parameter estimation.Based on the Wi Fi/ Bluetooth fingerprinting positioning results of a single terminal,the algorithm adds Bluetooth signal quantization distances between different terminals(including Smartphone and Bluetooth beacons with known positions),and constructs a refined random model considering the differences between different types of terminals.The experimental results show that compared with the single terminal fingerprinting algorithm,the algorithm can improve the positioning accuracy by 20%?30%,and the robustness of the positioning system has been improved to some extent.(3)The scheme design of peer-to-peer cooperative indoor positioning system based on smart phone is completed.The system adopts a client-server structure.During peer-to-peer cooperative positioning,each smart phone scans the surrounding Wi Fi spots and Bluetooth devices,and uploads relevant information to the positioning server.The positioning server runs the cooperative positioning algorithm to determine the position information of a plurality of interconnected positioning terminals(This is hereinafter referred to as "cooperative positioning groups".)within a certain range.(4)In addition,based on the scheme design of cooperative indoor positioning system,this paper develops a cooperative positioning system for experimental verification and analysis.Specifically,the indoor positioning APP is developed based on Android platform,the positioning server is built based on Windows platform,and a large number of experiments are carried out on the developed collaborative positioning prototype system,which verifies the effectiveness of the collaborative positioning algorithm proposed in this paper and the reliability of the collaborative positioning system.