Implementation Of Multi-point Communication Testing Emulator For V2X

Internet of vehicles(IoVs)aims to facilitate information exchange among vehicles or among infrastructure and vehicles,enabling intelligent traffic management and intelligent vehicle control,effectively reducing road congestion and improving road safety.The vehicle terminals,as a key part of IoVs,is the focus of users and researchers on the reliability and stability of its' communication function.At present,in order to evaluate the communication quality of vehicle terminals,testers need to do a lot of field measurement in different environments,which is time-consuming and laborious.Considering that the scene of IoVs have multi-points,moving scatters and inter-point interference,a multi-points network channel model with geometry-based stochastic(GBS)is established.Then a system implementation scheme of multi-node network channel emulator for IoVs is proposed,and on this basis a channel emulator for communication test of IoVs is developed,which can reproduce the effect of channel indoors on the communication quality of IoVs by real propagation and greatly shortens the research and development cycle of the vehicle communication equipment.The main work of this thesis is as follows:(1)The basic theories of channel fading,inter-point interference and channel noise in multi-point wireless channel are studied,and the deterministic model and statistical models of fading and interference are analyzed and compared respectively.And the multi-point network channel model for IoVs based on GBS is established,and the calculation process of fading model parameters with communication scene and vehicle motion trajectory is deduced,the calculation method of inter-point interference and channel noise is studied,and the correctness of the calculation method is verified by numerical simulation.(2)Aiming at the multi-point network channel model and the expected performance index,a prototype of the multi-point network channel emulator for IoVs is designed and implemented based on the NI PXIe hardware platform,and the application software including the user interaction interface and the realization scheme of channel parameter calculation are analyzed in detail,as well as the hardware implementation method for key modules with LabView FPGA such as the multipath delay module,channel overlay module and saturation intercept module.(3)The basic index and the scene of campus are measured and verified with the channel emulator developed in this paper,firstly,the performance indexes such as path loss,channel noise and channel fading are measured in detail with the typical test signal,and the measured results are consistent with the preset value or the theoretical value.Then,the emulation function of the system is measured with the video information transmission system,and also the field measurement is carried out under the real scene of the campus.The measured results show that the emulator can reflect the distortion effect of the actual propagation environment on the vehicle communication equipment,and can be used for semiphysical emulation of real-time duplex communication,dynamic networking and other characteristics of the vehicle equipment with channel influence and different topology structure,greatly shorten the research and development cycle of vehicle terminals and reduce costs.