| C-V2X(Cellular Vehicle-to-Everything)is a V2X(Vehicle-toEverything)technology based on Cellular Mobile Communication,which is standardized by 3GPP(The 3rd Generation Partnership Project).NRV2X(New Radio Vehicle-to-Everything)is the product of the combination of V2X and 5G technology.It mainly faces enhanced V2X applications such as platooning and advanced driving.NR-V2X provides wireless communication services with high reliability and low delay features.Resource allocation is one of the important technologies in NR-V2X,which mainly solves the problem of efficient allocation and management of limited wireless resources.In the distributed resource allocation approach of NR-V2X,the transmitting vehicles autonomously occupy wireless communication resources through sensing-based resource selection and periodic reservation.The approach takes advantage of the periodic transmission characteristic of V2X application messages,and has the advantages of improving resource utilization and reducing signaling overhead.However,it still faces the problems of half-duplex,hidden terminal problem,and insufficient support for new scenarios such as vehicular relaying and multicast,etc.Therefore,this thesis focuses on the resource conflict incurred by hidden terminal problem and the resource allocation for connectionoriented multicast scenario of the distributed resource allocation approach of NR-V2X direct communication.The main contributions of this thesis include:(1)A distributed resource allocation approach for the hidden terminal problem is proposed.In this approach,vehicles monitor the decoding of resources,use channel parameters to determine conflict resources from failed resources,and use resource fragment to broadcast conflict resource coordinates.Based on feedback information,the receivers evaluate the selected probability of available resource sets through FBARPE(Feedback-Based Available Resource Probability Evaluation Algorithm).FBARPE adds the influence of feedback information on the basis of random selection strategy to expand the acquisition range of vehicles resource occupation,so as to effectively alleviate the hidden terminal problem.(2)A connection-oriented distributed resource allocation approach for NR-V2X multicast scenarios is proposed.In this approach,platoons are divided into multiple sensing groups through DBDGS(Distance-Based Dynamic GL Selection Algorithm)and use the sensing results of each GL(Group Leader)to select the resource set.Platoon leader allocates resources to platoon members through CRSF(Candidate Resource Set Filter Algorithm).This approach uses group-sensing to select resource set to alleviate the unfair problem of PL-sensing.Resource conflict is effectively reduced by using CRSF. |
