The Data Distribution Technology Based On Wi-Fi Direct For Cooperative Vehicle Infrastructure System

With the rapid development of vehicle networking technology, the information interaction between vehicle and road has became one of the key issues for the traffic system. Car-road traffic data has the characteristic of strong real-time and high suddenness, so research of the interaction method for cooperative vehicle infrastructure system is particularly urgent, especially the data distribution efficiency and mechanism may directly affect the data sharing real-time and reliability. Wi-Fi Direct is a new short-range wireless communication technology, now is to be attended and promoted widely. The paper mainly studies data distribution in the cooperative vehicle infrastructure interactive system by using Wi-Fi Direct, and through improving access methods and distribution algorithm to meet the efficient transmission requirement.Firstly, the paper analyzes the characteristics of the cooperative vehicle infrastructure system application, and studies Wi-Fi Direct standard and its access mechanism.By analysising the current lack of access performance in the cooperative vehicle infrastructure system,the paper proposes a Wi-Fi Direct fast access method based on filtering information, effectively raising the speed of the vehicle-mounted device access roadside base station.Secondly, the papper studies the data characteristics and transfer mechanism of the system, also describes the principles, advantages and advantages of the existing data distribution algorithms such as FCFS algorithm, RM algorithm, and EDF algorithm.Then the paper analyzes those algorithms’ viability in the car-road system. Aiming at strong real-time dynamic priority algorithm EDF, the paper proposed an improved algorithm APEDF with variable cycle and proposed CR-APEDF data distribution algorithm by combining with car-road environment data distribution requirements.Finally, the paper designs and implements a data distribution software on Android platform, including Wi-Fi Direct access module, socket communication module, data transmission module and algorithm module. In a real car road scene, the paper uses the software testing the performance of fast access method and CR-APEDF data distribution algorithm by using the software.The testing results show that the Wi-Fi Direct fast access method based on filtering information improved upon 30% on the access speed; the CR-APEDF algorithm better than others on the indicators of task miss rate、average latency and processor utilization; The software distribution system including CR-APEDF algorithms has a large data throughput under static and dynamic environments, so it meets the real-time requirement in the cooperative vehicle infrastructure system.