Research On Vehicular Communication System In The Loop Testing Method Based On Channel Emulation

The testing and evaluation of intelligent connected vehicles is the key technology of research on the vehicle intelligence.Traditional road testing methods require a large amount of driving mileage to verify,which wastes both time and materials and has risks of accidents.Therefore,hardware-in-the-loop simulation testing is an efficient and safe method.The intelligent vehicles’ perception system includes Radar,Li DAR,camera and vehicular communication.Vehicular communication is a wireless information interaction system that uses VANET(Vehicular Ad Hoc Network)or cellular networks to achieve vehicle-to-vehicle,vehicle-to-infrastructure and vehicle-to-pedestrian communications.The application scenarios of the vehicular communication consider the propagation of wireless signals compared with the other two sensors.Thus,it is challenging for testing to emulate the channel conditions of the real environment.So,it is the basis for the design and development of the vehicular communication and the prerequisite for the vigorous development of intelligent connected vehicles that building the testing platform with channel emulation and high reliability testing method.This paper carries out a research on vehicular communication system in the loop testing method based on channel emulation supported by the National Key R&D Program of China(2018YFB0105103).First,the channel model based on the extraction of scenario elements is established by analyzing the channel features of the vehicular communication.Next,the vehicular communication system in the loop testing platform is built after designing the framework and principle of it.And then,the testing methods of wireless communication and autonomous driving algorithm performance are considered.Finally,several testing experiment is completed to verify the feasibility of the testing methods.The main research contents of this paper include the following four aspects:(1)Wireless channel emulation based on scenario elements extractionThe vehicular communication channel model is established with considering the propagation principle of wireless signals and the features of the vehicular communication.When the related elements are extracted from the simulation scenarios in real time,the parameters of channel model such as multipath,Doppler,fading can update dynamically.(2)Vehicular communication system in the loop testing platformThe principle and structural framework of the vehicular communication system in the loop testing platform are described.Then,to solve the clock synchronization of hardwares,GNSS positioning,data transmission and other issues,the modular control system and software kits of the NI platform is selected.After completing the platform,the channel model is realized through programming.(3)Communication performance testing methodsConsidering the long distance and high mobility in the vehicular communication application scenarios,the performance of the tested equipment under static and dynamic channel conditions is tested.The evaluation indicators include delay,packet loss and SNR.Finally,the feasibility of the testing method is verified through several testing experiments and analysis of results.(4)Autonomous driving algorithms performance testing methodsA closed-loop testing method centred on simulation scenarios is designed,which aimed at the autonomous driving algorithms based on vehicular communication.By injecting virtual signals generated in the simulation scenarios into the device under test,and adjusting the signal source power and propagation path gain parameters at the same time,the functions of the algorithms are tested in different scenarios.Also,finally,the feasibility of the testing method is verified.