Research On C-V2X Emergency Message Propagation Scheme Of Ultra-Reliable And Low Latency Applications

To meet the ultra-reliable and low latency communications requirements of emergency message dissemination in-vehicle security applications,the wireless communication systems should have to support millisecond end-to-end latency and close to 99.999% reliability.However,existing broadcast or multicast strategies such as Dedicated Short Range Communication(DSRC)or LTE-based Vehicle-to-Everything(LTE-V2X)are difficult to meet both reliability and latency requirements,and there is an urgent need to research relevant technologies for ultra-reliable and low latency communications.To better support advanced V2 X applications with ultra-reliable and low latency communication requirements,the New Radio V2X(NR-V2X)has been expanded and enhanced based on LTE-V2 X.This thesis focuses on the research on the key technologies of the emergency message dissemination of cellular V2X(C-V2X)with ultra-reliable and low latency,and it is specifically developed into the following three aspects.1)Research on the delay performance of message propagation under sufficient resourcesA scheme of unicast message propagation under the condition of sufficient resources in NR-V2 X mode 1 is proposed.First of all,while satisfying the real-time requirements of CV2 X message dissemination,the problem of maximizing message dissemination coverage is proposed.Then,to solve this problem,an algorithm HKVR based on maximum matching to maximize the coverage of k nodes is proposed,which is used for seed node selection and message propagation path planning in the process of message dissemination between vehicles.Finally,the actual trajectory of the vehicle is used to generate a dynamic topology map,which is used to verify the effectiveness of the HKVR algorithm.Experimental results show that the HKVR algorithm has significant advantages over the classic centrality-based algorithm in terms of the delay and coverage of message dissemination.2)Analysis of the reliability of message dissemination under limited resourcesThe link reliability of unicast concurrent message propagation under the condition of limited resources in NR-V2 X mode 1 is analyzed.First,under the assumption that the number of vehicles arriving at a certain road section per unit time obeys the Poisson distribution,a closed-form expression for the link reliability of the message propagation is obtained,and the conversion relationship between link reliability and user capacity is given.Then,according to the macro configuration of the system,a message dissemination control algorithm(MDC)is proposed to control the number of concurrent dissemination nodes to optimize the user capacity in the process of message dissemination.The experimental results show that the MDC algorithm can maximize the user load under the premise of meeting the reliability requirements of the link.3)Research on the ultra-reliable and low latency strategy of message dissemination under limited resourcesTo meet the high reliability and low latency performance requirements of NR-V2 X emergency message dissemination,the problem of maximizing message dissemination coverage is proposed.To solve this problem,a message dissemination algorithm(HKVP)under the condition of limited system resources is proposed.When selecting the seed vehicle for message dissemination and planning the message dissemination path,first calculate the current user capacity,and then limit the number of vehicles that send messages at the same time according to the user capacity,to ensure system reliability.Finally,using SUMO and OMNe T++ to build a simulation platform to implement the HKVP algorithm,the simulation results show that the HKVP algorithm has a wider message coverage than the classical centrality scheme while ensuring link reliability and delay performance.