High-Integrity File Transmission Method In Urban VANETs

In recent years,the rapid development of VANETs has attracted extensive attention in both academia and industry and various VANETs applications have emerged.Many VANETs applications are based on the file transmission between vehicles,so it is increasingly urgent to ensure the complete and reliable file transmission in urban VANETs.However,due to the variable vehicle movement,the diverse road environment,the complex wireless channel and the unstable link connection in urban VANETs,it is very challenging to realize complete and reliable file transmission in urban VANETs.On addressing this issue,this thesis proposes the high-integrity file transmission method in urban VANETs.Firstly,this thesis develops a vehicle movement model in urban to predict the distance and communication time between vehicles.Then,this thesis establishes the V2 V physical layer communication model and MAC channel contention model.Given the above models,this thesis is able to evaluate the transmission capacity.Based on the transmission capacity,a VANETs cooperative transmission method is proposed to ensure the integrity and reliability of files.In this method,when a sender vehicle receives a file request from a receiver vehicle,the transmission capacity between tow vehicles will be calculated to judge the probability of successful transmission.If the probability is higher than the threshold,the file will be transferred directly.Otherwise the sender vehicle invites the appropriate neighbors to join the cluster until the total transmission capacity is greater than the file size.Then the file is split according to the transmission capacities and sent to the corresponding vehicles.Finally,the receiver and the relay vehicles form a chain cluster to help transmit the file fragments.When the transmission is completed,the receiver will splice the file fragments into a complete file.In this thesis,a simulation experiment of urban traffic environment is built by SUMO platform.The NS3 simulation platform is used to realize the method proposed in this thesis.And this method is analyzed and compared with the existing CFT and IOCT methods which are focus on the file integrity transmission.The simulation results show that the proposed method can effectively improve the integrity and reliability of the file transmission in urban VANETs.