Research On The Multi-dimensional Assisted Download Method Of Space-Time-Frequency In VANET

Vehicular Ad-Hoc Network(VANET)has broad development prospects as a communication medium for transmitting road safety,traffic efficiency and entertainment media information.The data download demand of vehicle users is increasing.Although 4G/5G communication technology can support wireless network services,due to the high deployment cost and the sparse distribution of base stations,full network coverage cannot be achieved.The provision of low-cost,high-capacity data download services by roadside infrastructure has become an effective supplement to cellular communications.In expressways,the roadside infrastructure is sparsely distributed and the coverage area is limited.The assisted downloading technology of assisting the transmission of data through surrounding vehicles and expanding the coverage of roadside infrastructure has become a research hotspot.However,the current research on the Internet of Vehicles assisted downloading still has the problems of low data download during the transmission process and difficulty in guaranteeing transmission security.In response to the above problems,the main work and innovations of this thesis include:1.Aiming at the problem of low data downloads in the process of assisted download and transmission of the Internet of Vehicles,a multi-dimensional assisted download method based on time,space and frequency is proposed.Firstly,the Internet of Vehicles assisted download scene is modeled as a three-dimensional state model based on time,space,and frequency,and the utility function is designed according to the position of the node and the connection time between the nodes,which is used as the basis of the car selection strategy.Then a dynamic block method of the blind zone is designed to reduce the complexity of the algorithm.Finally,bipartite graph matching is used to calculate the optimal network structure.Simulation experiments show that this method can effectively improve system throughput.2.Aiming at the problem that the target node cannot obtain the assistance service due to the selfishness of the assisting node in the assisted download of the Internet of Vehicles,the target node is not able to obtain the assistance service,and a data distribution strategy based on credibility is proposed to further improve the utilization rate of blind spots and reduce the impact of dead pixels.By evaluating the interactive services between the target node and the assisting node,the past credibility of the target node and the assisting node is defined as direct credibility,and the credibility of other nodes to the assisting node is indirect credibility.Reliability is one of the elements based on the selection of cars,which reduces the probability of malicious nodes participating in assisting forwarding.Simulation experiments show that this scheme effectively reduces the influence of malicious nodes on the system and improves system performance.