Analysis And Optimization Of Access And Reselection Process In LTE Network

As a typical representative of the fourth generation mobile communication system,Long Term Evolution(LTE)technology has made outstanding achievements in various fields and even changed the structure of some industries,but with the passage of time,especially the beginning of 5G commercialization,some of the potential problems in LTE,such as the difficulty of building large base stations in complex scenarios,the high cost of upgrading and operation and maintenance began to gradually emerge.Building a dedicated small base station based on SDR equipment can be used as one of the solutions to the above problems.In the context of a dedicated network,this thesis uses the International Mobile Subscriber Identification Number(IMSI)as the identity to divide users into authenticated users and non-authenticated users.By focusing on user access and mobility management processes,the access and disconnection schemes of the two types of users were differentiated,and the relevant parts of the OAI platform were customized.A simulation system was built to simulate the actual scene.Finally,system testing and analysis were carried out.The main work is summarized as follows:1.Analyzed the structure of the OAI platform and the role of the main modules.It focuses on the PLMN selection,cell selection,cell reselection,attachment and tracking area update processes based on the OAI platform,and points out the imperfections of the platform.In order to reduce the impact of the private network on non-authenticated users,the unauthorized user exit strategy is designed to use TAU Reject and RRC Connection Release to avoid the impact of the private network on the user authentication function of the private network.Repeatedly access the private network.2.Completed the overall scheme design of building a dedicated network,rationally designed and improved each module according to the previous theoretical analysis,improved one by one in the project and paved the way for the automated deployment scheme.Finally,the relevant SIBs used by the UE for cell selection and reselection were completed,the Attach and TAU processes were re-integrated,and the whitelist was used to complete the private network identity authentication scheme,and a reasonable departure strategy for non-authenticated users was realized.3.Build an OAI platform using USRP B210 and PC,test the improved and newly added SIBs,design a quantitative experiment and analyze the impact of RSRP on the success rate of cell reselection,and verify the UE's cell in idle mode Reselection strategy and identity authentication process.The test results show that the terminal on the public network can reselect to the private network built in this thesis The non-authentication users specified in the experiment can be separated according to the set plan.The experiment is generally in line with the expected test results.