Design And Implementation Of Receiving System For The Multi-station Fingerprint Position

As the rapid development of mobile communication and wireless Internet of Things technology,the demand on LBS for the terminal and node devices have been generated extensively on the fields of business,medical and public safety.Due to the outstanding performance of accurate positioning in complex NLOS scenarios,the fingerprint positioning technology has become a research hotspot in the academic circles of mobile communication technology in recent years.According to the planning arrangement of the multi-station LTE terminal fingerprint positioning technology and the system development tasks,the paper mainly carried out research and development work on LTE uplink receiving system,which can provide support for the target system to obtain high-quality terminal fingerprint signal information.The main researches are as follows.(1)According to the characteristics of actual application scenarios of the terminal fingerprint positioning program,one kind of system wireless channel simulation model based on the ray tracing model method is given.In order to solve the problem of symbol synchronization accuracy under high-delay multipath channels,the receiving symbol synchronization algorithm using coarse synchronization and fine synchronization is proposed according to the LTE-A uplink physical layer protocol standard,in which coarse synchronization is implemented by using DMRS sliding window correlation operations based on peak detection,and fine synchronization is achieved by using the improved multi-symbol differential CP synchronization algorithm to compensate for the effect of multipath delay on coarse synchronization.The simulation comparison analysis with related algorithms shows that the designed synchronization method makes the receiving system the overall synchronization performance has been effectively improved.(2)Through the comprehensive analysis of classic channel estimation algorithms such as LS,MMSE,and transform domains,as well as according to the technical characteristics of the project system and its requirements for algorithm accuracy and technical feasibility,the symmetric extended DFT estimation algorithm is adopted,and the DWT algorithm is introduced to solve the problem of noise which is in the energy concentration interval and the deterioration of estimation result due to the few number of pilots.DWT algorithm was used to improve the accuracy of channel estimation by denoising the threshold of high frequency wavelet coefficients.On this basis,the CFR at the pilot position obtained by the improved channel estimation is subjected to matrix transformation to generate the ADCPM matrix of fingerprint information.Simulation results show that the designed channel estimation scheme can improve the denoising performance in the energy concentration interval,and the estimated stability under different pilot numbers,which meets the needs of the receiving system to output high-quality fingerprint information.(3)Based on the USRP N310 hardware platform,the receiving system is implemented and developed by GNU Radio tools.According to the GNU Radio system framework,the symbol synchronization,channel estimation and DMRS generation modules of the receiving system are designed,which includes the OOT module,Flow graph,and key code SSE optimization.The verification results show that the implementation module of the receiving system has achieved the function and performance goals,which laid a solid foundation for the implementation of the multi-station terminal fingerprint positioning system.