Research On Transmission Architecture And Protocol Improvement Of Vehicle Ad Hoc Network Based On Integrated Public Transport System

Intelligent Transportation System(ITS)is to improve the traffic environment,the realization of intelligent interconnection between vehicles designed network system,ITS core is Vehicle Ad-Hoc Network(VANET),which has the characteristics of fast network topology change,strong scalability and high autonomy,can enable networked vehicles to send and receive real-time information about the current traffic conditions,thus reminding drivers of the current road conditions.Due to the fast moving speed of the vehicle,the application layer requires high delay and delivery rate of the packet.this thesis combines the characteristics of VANET,improves the VANET network architecture and its transmission protocol,and carries out application tests to improve the overall performance of the VANET.The research work of this thesis includes the following three parts:(1)A new VANET network architecture is proposed,which introduces traffic infrastructure and public transport vehicles,and integrates them with private vehicles.In the new network architecture,communication between vehicles transmits data through buses and assisted by Road Side Unit(RSU)and Traffic Control Center(TCC),where RSU is used to ensure service coverage,while TCC helps to locate the target vehicle quickly.The experimental results show that the proposed new architecture has better performance than the traditional VANET,significantly reduces the transmission delay and has higher data delivery rate.(2)Aiming at the serious problem of data packet collision in high-speed vehicle movement,two MAC protocols based on Time Division Multiple Access(TDMA)are proposed in combination with the proposed network architecture,which are based on Slot Migration-based MAC protocol ZA-MAC and Predication-based MAC protocol ZT-MAC.ZA-MAC is specially designed for two-way traffic roads,It aims to reduce the number of data packet collisions.ZT-MAC can be used for two-way roads and four-way crossroads to predict data packet collisions and eliminate them before collisions occur.Experiments show that the proposed protocols achieve the desired results.(3)In order to further improve the transmission performance,a test platform was built using Dedicated Short Range Communications(DSRC)components to test the transmission performance of streaming video data in VANET.Experimental tests show that the proposed retransmission and caching strategy improves the reliability of data transmission in VANET and reduces the packet loss rate of streaming packets.