Research On Performance Optimization Of NR Based V2X Communication

With the rise and development of the Vehicle to Everything(V2X)communication technology,the 3rd Generation Partnership Projet(3GPP)has begun to promote the standardization of New Radio(NR)based V2X communication technology,also called NR-V2X.This release can better support unmanned driving,autonomous driving and other new features,while at the same time,it has higher requirements on communication delay and reliability.Radio resource allocation is an important part of designing an NR-V2X communication system.According to the 3GPP NR-V2X standardization process,it can be known that NR-V2X supports the user equipment(UE)autonomous resource selection mode.In this resource allocation mode,the resource selection process will affect the physical layer delay and transmission reliability.Therefore,for NR-V2X communication performance optimization technology,this thesis mainly studies the following two aspects:First,according to the resource selection process in the autonomous resource selection mode,an optimization scheme based on channel busy ratio and a hybrid optimization scheme based on resource collision detection results and channel busy ratio are proposed.The two schemes combine parameters such as packet priority,reliability requirements,resource collision probability,number of collisions,and channel busy ratio to adjust the resource selection window size with the goal of balancing delay and reliability under different scenario requirements as far as possible,while considering the communication scenario and communication requirements,to ensure the physical layer delay and lower probability of resource collision.The simulation results show that the two schemes both can improve the communication performance under different communication scenarios and different performance requirements,and the hybrid optimization scheme based on the resource collision detection results and channel busy ratio is more optimized under the condition of lower resource pool occupancy.Secondly,in order to solve the problem of resource collision detection,under the Orthogonal Frequency Division Multiplexing(OFDM)signal waveform with cyclic prefix,this thesis proposes to use mixed signal detection and identification technology.Among them,the mixed signal detection algorithm based on the squared spectrum feature obtains the number of mixed signals and the sub-signal bandwidth by detecting the number of squared spectral lines.The simulation verifies the effectiveness of the algorithm and obtains the detection success rate under different sub-signal bandwidth and signal-to-interference conditions.The mixed signal detection algorithm based on spectral characteristics analyzes the spectral width and amplitude of the mixed signal to obtain the mixed signal detection result.The simulation verifies the effectiveness of the algorithm and obtains the detection success rate of the algorithm under different frequency offset ratios.When the frequency offset is small,the detection success rate is greatly improved.The successful detection of mixed signals indicates that resource conflicts occur at the resources occupied by the signals.The number of detected sub-signals is used to measure the number of UEs in conflict.The two results are used as input parameters for the hybrid optimization scheme based on the resource collision detection results and the channel busy ratio,to futher optimize resource selection and communication performance.