Research On Hybrid Routing Protocol Based On Opportunity Communication In Vehicular Ad-hoc Networks

Vehicular Ad-hoc Networks(VANETs)is an implementation in Internet of Vehicles,and the design of routing protocol is the key technology for VANETs to achieve reliable multi-hop transmission,which is also one of the research hotspots of VANETs.In VANETs,fast movement of nodes lead to the rapid change of topology and poor connectivity,but the opportunity forwarding mechanism based on "storage-carry-forward" model can be well applied in this specific traffic environment.This dissertation focuses on the research of data transmission in VANTEs,and a hybrid routing protocol that can forward opportunities without pre-establishing a complete routing path is designed,and verify it in the experiment.The experimental results show that the protocol can effectively improve the stability and scalability of transmission in VANETs.The prime research work is as follows:An overview of routing protocols in vehicular self-organizing networks was summarized,and the principle of PRoPHET routing algorithm and its defects in VANETs were analyzed.Combining with actual traffic environment,a probabilistic routing algorithm based on the duration of encounter between nodes(PRoPHET-CT)was proposed.The algorithm combined the PRoPHET protocol with the duration of the encounter between nodes,which not only considered the efficiency of message transmission,but also the reliable transmission of messages when two nodes meet was under investigation.The experimental results showed that the improved protocol increases the successful forwarding efficiency of messages,reduces network load,and decreases the average hop count.Aiming at the performance of network degradation caused by blind flooding forwarding of multi-copy-based Spray and Wait routing algorithm,a hybrid routing algorithm based on opportunistic forwarding was proposed in this dissertation.In the Spray phase,the probabilistic prediction based on the encounter connection time and the number of connections between nodes in the PRoPHET-CT routing algorithm were introduced to evaluate the transmission capacity of the nodes.Meanwhile,the number of message copies was dynamically allocated to nodes with different transmission capabilities.In the Wait phase,the relay nodes were determined by the movement properties and the encountering index of nodes,and the policy of passive waiting for the destination nodes was changed to active searching for a more suitable next hop node for forwarding the message.The proposed PRoPHET-CT and hybrid routing algorithms were compared and analyzed on the ONE simulation platform.The results revealed that,compared with the Epidemic,the PRoPHET,and Spray and Wait routing algorithms,the improved route enhances the successful forwarding efficiency of the message,reduces the network load and improves the overall performance of the network.