Traffic And Communication Congestion Avoidance Mechanism Design And Verification Based On VANET

In recent years,with the continuous improvement of economic level,the number of urban vehicles in China is increasing and urban roads are under the great pressure.VANET technology can effectively alleviate the serious traffic congestion problems.But with the rapid development of VANET and the expansion of the network scale,how to utilize the existing network resources effectively and control the network congestion problem in real time by dynamic routing in order to improve the communication efficiency of VANET is particularly important.In this paper,we focus on the problem of traffic congestion on urban roads and network congestion in VANET.From dimensions of the traffic flow and information flow,we combine VANET technology with Ant Colony Algorithm to design two different types of congestion avoidance mechanisms:Traffic Congestion Avoidance Mechanism Based on Improved Ant Colony Algorithm;We use the V2I communication technology of VANET and improve the Ant Colony Algorithm to carry out the heuristic dynamic path planning.The algorithm uses the vehicle ants to collect real-time traffic data to predict the traffic situation in the short term.We consider the complex and dynamic traffic factors to improve calculation rules of the state transition probability and pheromone updating.We do not only consider the recurrent traffic congestion but also and deal with the non-recurrent traffic congestion caused by traffic accidents,road construction,weather conditions.In addition,we generate packet ants periodically to calculate multiple alternative paths for each origin-destination pairs in the road network.According to the different types of vehicles,we combine the priority scheduling with the first-come-first-service strategy to allocate routes to the vehicles and decentralize the traffic flow.Communication Congestion Avoidance Mechanism Based on SDN-V:Due to the high mobility of the vehicle nodes,the high dynamic of the network topology and intermittent connection,we apply SDN technology to VANET and design a hierarchical network architecture.We separate the control plane from the data plane in the vehicle nodes and make vehicles just be responsible for effective data forwarding.The centralized controller is used to control the global network topology and call the improved Ant Colony Algorithm to carry out the dynamic routing,so as to maintain the network load balance,control the network congestion and improve the communication efficiency of VANET.In this paper,we carry out the simulation experiments by coupling the traffic simulator SUMO with the network simulator NS3.The experimental results show the practicability of Traffic Congestion Avoidance Mechanism Based on Ant Colony Algorithm to alleviate the traffic congestion and the effectiveness of Communication Congestion Avoidance Mechanism Based on SDN-V in dealing with network congestion and improving the network performance.