Research,simulation And Optimization Of Positioning Algorithms Based On Reference Signals In 5G System

In the context of rapid economic and industrial development as well as rapid iteration of mobile communication technology,5G will carry out in-depth cooperation with all walks of life,striving to break through traditional concepts and drive social development.In the 5 G era,location-based services are closely related to people's life,entertainment,health,emergency rescue and disaster relief,which breeds huge business opportunities.In the future,with the gradual deployment of ultra-dense network,the number of micro-base stations will increase significantly,which makes the use of widely existing base stations for positioning become a very convenient and accurate way.At the same time,3 GPP has added a reference signal PRS for the base station positioning method to improve the positioning accuracy,which can be used in combination with a variety of positioning technologies.Therefore,this thesis studies,simulates and optimises the multi-base station positioning algorithm and process based on PRS in 5G system.The main work completed is as follows:(1)Aiming at the research and optimization of reference signal and positioning algorithm,firstly,the downlink and reference signal in the physical layer of 5G NR system are studied,and the basic location technology is elaborated,with the focus on the positioning method based on distance measurement.Secondly,the different distribution of PRS in a frame is simulated and analyzed,and a new PRS sequence generation mechanism is proposed according to the autocorrelation performance of PRS.Finally,the three-dimensional CHAN positioning algorithm based on OTDOA is deduced and improved.(2)Aiming at the simulation and optimization of the positioning process,firstly,a positioning platform was designed and built according to the three main modules of the network side,the user side and the base station side,and the functions of the main units in each module were added and improved.Secondly,the scene of 5G dense cell is modeled using stochastic geometric Poisson process PPP,and relevant standards and parameters of 5G are used for setting and debugging of the positioning platform.Finally,the usability and accuracy of the platform are verified by relevant simulation,and the simulation results are analyzed.(3)Aiming at the selection and optimization of the positioning base station in a dense cell scene,the three-dimensional accuracy factor DOP was firstly studied and derived.Secondly,the influence of different base station topological distribution on location error is analyzed through a lot of simulation,and a better UE-base station topological distribution rule is summarized.Finally,the optimization scheme of base station selection based on topology is proposed to improve the positioning accuracy.The platform and research contents of this thesis can provide the basis for further researches and simulations on other factors affecting the positioning accuracy,which has a certain practicability and value.