| In recent years,as the number of cars around the world continues to rise,road safety issues and traffic congestion have become increasingly prominent.As a Vehicleto-Everything(V2X)solution that can effectively solve traffic accidents and improve traffic efficiency,Cellular Vehicle-to-Everything(C-V2X)is in an important stage from planning to landing in China.The construction of communication infrastructure is the foundation for the landing of C-V2 X,with the increase in penetration of road-side unit(RSU)and on-board unit(OBU),network builders and maintainers urgently need to provide practical data support for network planning and optimization through a large number of actual drive test.This thesis studies the key technologies of wireless network drive test scanner,and designs and implements LTE-V2 X wireless network drive test scanner based on software defined radio(SDR)according to the unique propagation environment of V2 X,high-speed movement of vehicles,limited mobile area,low antenna height,which provides practical and powerful support for the deployment planning of RSU and the formulation of OBU vehicle-side driving strategy.The characteristics of large relative motion speed,low antenna height and long synchronization signal period between V2 X communication nodes increase the timing synchronization error of the receiving end symbol,affect the system communication performance,and even cause timing synchronization failure to cause packet loss.This thesis analyzes the advantages and disadvantages of the existing symbolic timing synchronization algorithm,designs an improved symbolic timing synchronization algorithm for the V2 X communication scenarios,and effectively improves the robustness of the improved algorithm in the scenarios of high frequency bias and low signal-to-noise ratio of the networking channel of the vehicle networking through the processes of algorithm fusion,threshold design and frequency offset compensation providing a theoretical basis of symbolic timing synchronization module of LTE-V2 X drive test scanner design.Fast motion speed and high density of OBU lead to transmission resource reselection frequently,which challenges the computational processing power of the drive test scanner.In this thesis,the sidelink traffic channel(STCH)reception process is studied,including blind detection of the physical sidelink control channel(PSCCH)and the decoding of the physical sidelink share channel(PSSCH).Aiming at the PSCCH blind detection algorithm requires multiple complete link-level processing,this thesis designs a low-complexity PSCCH blind detection algorithm using demodulation reference signal(DMRS)correlation.The improved algorithm extracts the resources grid that PSCCH located in and performs the maximum likelihood judgment after it is related to the local DMRS,so that the drive test scanner obtains the frequency domain position of PSCCH and the type of DMRS before performing link-level processing,which greatly reduces the complexity of the channel receiving algorithm.This thesis design and Achieve LTE-V2 X wireless network drive test scanner,the wireless signal is collected through the universal software radio peripheral(USRP),the subsequent signal processing is carried out by the MATLAB software platform,realize real-time calculation and output of wireless network quality parameters,real-time display of PSCCH and PSSCH constellations and channel impulse response,while the GPS time and location information is coupled.Finally,this thesis builds a laboratory test platform and an outdoor test platform to verify the correctness and integrity of the LTE-V2 X drive test scanner. |
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