The Study On Location Based Services In 3GPP/LTE Network

In recent years,the global wireless communication technology has experienced a substantial leap,especially 3GPP/LTE network technology in wireless communication.With the rapid development of Mongolia's mobile communication system,the number of mobile users has continuously increased,the communication quality has also been improved,and many new service businesses have been developed.In addition to traditional voice communication services,the 3GPP/LTE system adds other new service functions.Among them,Location Based Services(LBS)has been widely used,and positioning technology is one of the key technologies for implementing LBS.The research of wireless network location technology is carried out around two core issues.One is how to obtain more accurate TOA(Time of Arrival),TDOA(Time Difference of Arrival)and AOA(Angle of Arrival)in a complex and varied wireless channel environment.The electric wave characteristic measurement value;the other is to design a reliable and effective positioning scheme and a high-precision positioning processing algorithm.In this paper,mobile terminal location in Mongolia 3GPP/LTE network is studied.Based on AOA,TDOA and extended Kalman filter,a TDOA/AOA algorithm based on extended Kalman filter is proposed.This algorithm has high positioning accuracy and can track mobile users in real time and dynamically.The main contents and research results are as follows:(1)Firstly,this paper summarizes the research background and status quo of the subject,introduces the commonly used location technology and evaluation indicators of location performance in cellular networks,and focuses on the principles and mathematical models of TOA,AOA and TDOA.Through comparative analysis,TDOA/AOA algorithm is selected as the research focus of this paper.(2)Single-station TDOA/AOA location algorithm in 3GPP/LTE network is studied.In order to track and locate the moving target mobile station,an extended Kalman filter based on TDOA and AOA is proposed to locate the moving target.The extended Kalman filter is used to track the moving target dynamically.(3)The LBS implementation process of TDOA/AOA positioning method based on extended Kalman filter(EKF)evaluates the performance of all aspects of the algorithm for different base station antenna positions(horizontal and vertical)and mobile station position changes under the preset cell radius,and comprehensively analyses the positioning effect of LBS.The positioning error performance of TDOA/AOA algorithm based on extended Kalman filter and Taylor sequence expansion algorithm in static positioning method are compared and analyzed.Finally,simulation results show that the former has higher positioning accuracy.