Design And Implementation Of V2X Roadside Equipment Based On Vehicle-road Collaboratio

With the increase of urban population and the number of motor vehicles,the urban traffic situation is becoming more and more complex.Traffic efficiency and driving safety have become two major problems.However,with the continuous development of transmission and information industry,solving traffic problems through technical means has become the research direction at this stage.Compared with automatic driving and assisted driving,cooperative vehicle infrastructure system(CVIS)has the advantages of wide service range,rich application scenarios and low deployment cost.Road-side unit(RSU)is a key link to realize the function of cooperative vehicle infrastructure system.How to design the function of road-side unit and related transmission protocol has become the key to the effective operation of cooperative vehicle infrastructure system.This thesis focuses on the design and implementation of road-side unit hardware and software modules,and designs relevant scenarios for testing.The main research work and innovations are as follows:1)In terms of hardware design,the performance and interfaces of various constituent modules are investigated,the hardware composition framework of road-side unit is constructed,the development environment based on Linux system is adopted,the functions of each module are debugged,and the performance of each constituent module is compared with the design standard of road-side unit.The debugging results show that the selected hardware modules meet the road-side unit design standards,and the software development can be carried out on this basis.2)In terms of software design,according to the transmission performance requirements in different scenarios,an application layer protocol stack suitable for cooperative vehicle infrastructure environment is designed.This protocol stack adopts hybrid protocol design.Different transmission protocols are designed and implemented for traffic efficiency applications,traffic safety applications and cloud macro-control applications.Based on the traditional protocol,the concept of electronic fence is introduced.An emergency supplementary protocol is designed for low signal coverage.At the same time,unaligned packet encoding rule is adopted to ensure the security of the transmission process.Experiments show that the transmission delay in each scenario is millimeter level,which meets the transmission performance requirements in the connected vehicle environment.3)According to the typical scenarios of connected vehicle(CV)formulated by the National Intelligent Transportation System Standardization Technical Committee,several types of typical scenarios are selected for customized implementation,outfield test,detection function integrity and transmission performance.Among them,the road congestion scenario simulates a method to estimate the queue length at the intersection according to the location of connected vehicle.At the same time,a period level queue length evaluation index is proposed to evaluate the accuracy of queue length estimation results in the road congestion scenario.The proposed evaluation index has more stable evaluation performance in small sample scenario.