Research On Transmission Control Optimization Using Network Coding Based On Connectivity In Vehicular Ad Hoc Network

With the rapid development of economy,followed by the improvement of people's living standard,our country has already become one of the automobile industrial countries.The significantly increasing demands for road traffic lead to the increasing attention to Vehicular Ad Hoc Network,which is the specific application in the intelligent transportation system.The increasing requirement of data transmission is an inevitable result of the increasing demands for road traffic.There is an increasing focus on the time taken to acquire information and the information quality not just the capability of acquiring information.Therefore,how to improve the efficiency and reliability of data transmission in vehicular communication network is currently one of research hotspots.The optimization of data transmission based on network coding in the high-speed communication network is discussed in this thesis which mainly consists of two points as follows:Firstly,the data transmission must be established on the basis of inter-vehicle communication,therefore,an analysis model of the vehicular communication network based on the headway distribution is presented in the first part in order to ensure the effective communication between vehicles.The distribution of the headway is analyzed after considering the vehicle speed and direction.The vehicular connectivity and the calculating model of the connectivity is given.Analysis and simulation results show the relationship among connectivity,the arrival rate of vehicles and average vehicle density.Moreover,the predictive analysis of the optimal communication distance in highway is made to ensure connectivity during the process of data transmission in the further research.Secondly,in the case that any two vehicles within the communication range are well connected with each other,one or more relays are necessary to achieve mediate communication for those vehicles unable to communication directly with each other.Some vehicles are used as relay in this thesis,and an algorithm which takes the network connectivity,the traffic density and the channel condition into account is discussed,then the multi-path transmission control protocol based on linear network coding is proposed in this thesis.In order to decide whether it should hold the newly received packet and wait for an opportunity to encode packet or send it out immediately to reduce delay,the vehicles maintain a queuing buffer to hold the data received from other vehicles at first.Then the packets will be encoded and forwarded to relay by the source vehicle.The encoded packets will be decoded in the destination vehicle to acquire the original data.Simulation shows that the routing overhead and delivery rate are improved effectively using the proposed method in this thesis,thus the problem of low efficiency and data transmission can be solved.