Research On Routing Algorithms For Internet Of Vehicles Based On Bus Assistance

Recently,the intelligent transportation system(ITS)has been developed rapidly,owing to the continuous improvement of wireless network technologies and the increasing traffic demand.As one of the crucial technologies of ITS,vehicular ad-hoc network(VANET)is widely used in traffic management,mobile entertainments services and other scenarios to improve road traffic safety,and provide entertainment service information for drivers.Due to the complexity of VANET,there are three main problems in the design of routing protocol: i)the high-speed movement of vehicle nodes leads to frequent changes in network topology;ii)the trajectory of vehicle nodes is restricted by road topology,traffic rules and the subjective consciousness of drivers;iii)the random movement of vehicle nodes leads to uneven distribution of vehicle.Therefore,traditional routing protocols cannot guarantee the communication quality in the VANETs.It is necessary to design efficient,real-time,and reliable routing protocols for VANETs.Aiming at the abvove problems existing in VANETs,considering the characteristics of the fixed trajectory,large communication coverage,less change in speed,strong ability to process and store data information of bus,this thesis employs bus as an auxiliary node to different transmission scenarios of vehicles communications,and the corresponding solutions are proposed according to transmission requirements.The main contributions of this thesis are as follows:(1)For the different kinds of packet transmission requirements in VANETs,this thesis proposes a routing algorithm which takes the bus as a relay node based on V2 V and5G cellular hybrid message transmission framework.Firstly,packets in VANETs are divided into two types: delay sensitive and delay insensitive.The delay sensitive packets can be transmitted efficiently taking the advantages of 5G cellular network with low delay,high reliability and wide network coverage.Considering the characteristics of large communication transmission range and fixed driving trajectory of bus,a routing algorithm with bus-realy is designed for delay insensitive data packets which uses the bus as a relay node to extend the communication transmission range and improve the routing performance.To reduce the probability of communication link disconnection,a neighbor table updating mechanism based on time prediction is proposed.Simulation results show that the proposed algorithm has a significant improvement on the packet delivery ratio,average end-to-end transmission delay and average transmission hops.(2)For a large amount of real-time data transmission from vehicles to infrastructure in the VANETs,this thesis proposes a routing algorithm based on the vehicle clustering.Firstly,the algorithm groups the vehicle nodes in the VANETs to construct a cluster with the bus as the cluster head.Then,the data information of nodes in the cluster is collected and preprocessed to reduce the redundancy by taking the advantages of abundant computing and storage resources of the bus.Finally,a multi-hop routing path based on bus-cluster-head is established by using relay selection algorithm for gateway node between adjacent clusters according to the location of the destination node.The routing path is dynamically adjusted according to the feedback of routing performance of packet transmission.Simulation results show that the proposed algorithm can adapt to the dynamic environment of VANET and improve the routing performance greatly.