Research On FDD-LTE Terminal Management Identity Information Detection And Random Access Technology

With the development and in-depth application of the fourth-generation mobile communication technology,the mobile communication industry has ushered in unprecedented prosperity.Intelligent terminal has become an indispensable information communication tool in human society,but it also exposes many information security problems.Nowadays,telecommunication fraud has become the main criminal means of many lawbreakers.The public security department needs to control all terminals in the criminal activity area to prevent their criminal activities,and at the same time,without affecting the normal communication of other users,block the communication between criminals and the outside world to arrest.Therefore,it is of great practical value to study a management and control system for specific target terminal communication.In this paper,the LTE protocol architecture is studied,and an fdd-lte terminal management and control system is designed,which can obtain the terminal identity information,identify the specific target terminal according to the identity information and block its communication.In addition,some control channel detection algorithms involved in the system are analyzed,and the performance of existing detection algorithms is compared and simulated.First of all,the existing pseudo base station management and control scheme is analyzed.Aiming at the problem that the circuit domain dumb call mode in the existing pseudo base station management and control technology can not absorb and control the volte terminal,a terminal adsorption scheme based on the mode three interference principle is proposed.This scheme combines the characteristics of LTE system in the same frequency network,and identifies the physical cell of the pseudo cell the setting of identifier(PCI)is the same as that of the service cell.Since the same cell after PCI mode 3,the location of the cell's dedicated reference signal is the same,and interference will occur under the same frequency,so that all terminals in the service cell(including the volte terminal)can be disconnected and connected to the pseudo cell.Under this premise,the identity detection and control scheme based on signaling process is designed,in which the GNU radio open-source software is used to scan the base station,and only one computer and USRP equipment are used to obtain the cell information of the base station.Compared with the expensive frequency sweeper,the equipment and maintenance cost are saved while the signal measurement accuracy is not reduced.Secondly,the preamble detection algorithm of physical random access channel in random access process is studied.In the medium and low speed environment,the success detection probability of semi dynamic threshold and fixed threshold preamble detection algorithm under different SNR conditions is tested.The results show that the former has better anti noise performance,and the root sequence grouping detection method reduces the delay.Finally,the software radio platform is used to realize the design.Through the USRP b210 device and openlte open source project,the LTE pseudo base station is built.Through modifying the openlte source code,the functions of the target user terminal identity acquisition and the black and white list control module are realized respectively,and the test is carried out one by one in combination with the test cell phone.The feasibility and correctness of the design scheme are verified.