Research And Design For Emergency Message Rebroadcast Mechanism In VANET

With the rapid development of modern science and technology, the increasing vehicle caused pressure to urban road safety. Intelligent Transportation Systems (ITS) integrate advanced computer, communication, and sensing technologies providing efficient traffic management and real time traffic states for safety and comfort for drivers. Vehicular Ad Hoc Network (VANET) is a promising platform for the Intelligent Transportation System (ITS).Car-following theory is a significant research direction in the field of VANET, it describes the one-by-one following process of vehicles on the same lane in traffic flow. The paper analyzed Krauss car-following model and proposes a new model based on Krauss model in SUMO 0.21.0 platform to improve the authenticity of car model and implements it on the SUMO platform. This model considers the movement state of the car and the gradual process of deceleration in vehicles braking. Simulation experimental results show the superiority of new model over other ones in simulation that models real streets. It achieves good results in wait time, travel time, lane-change number and safe speed.At the same time, the paper proposes a protocol of emergency message rebroadcast mechanism. When it rebroadcast via synthetic nodes, some vehicular nodes are selected to rebroadcast the message instead of by all received nodes, with considering multi-lanes and traffic density. Meanwhile, opposite vehicles are selected to rebroadcast the message in sparse traffic. Simulation and analysis results show that the packet loss ratio and reconnecting time can be reduced by using this mechanism.