Research On Time Synchronization Method For VANET And Development Of VANET Terminals

In recent years,with the rapid growth of the number of cars,the road carrying capacity in many cities has reached saturation.The problem of traffic safety,travel efficiency and environmental protection have become increasingly prominent.Traffic problems have become the key factor restricting further development of economy and society.People hope to improve the current traffic situation with the new generation of electronic information technology,sensor technology and computer technology.In this background,Vehicular Ad-hoc Network(VANET)has become a hot spot for the research of application.Due to the VANET's particular environment,such as fast-moving characteristic of the VANET node and changing of network topology,the traditional wireless communication protocols can not meet the actual application scenarios and communication requirements of VANET.Therefore,the IEEE issued the WAVE(Wireless Access in Vehicular Environment)protocol stack for VANET in 2013.However,there is no mature and car-mounted VANET communication terminal supporting the WAVE protocol stack.The goal of this dissertation is to develop a VANET communication terminal supporting the WAVE protocol stack.At the same time,time synchronization among VANET communication terminals is the key factor affecting the performance of VANET network.Therefore,another work of this dissertation is to analyze and study the time synchronization method among VANET communication terminals,and to realize the time synchronization method that meets the accuracy requirement of WAVE protocol.The main work of this article is summarized as follows:1)The multi-channel coordination in the WAVE protocol is implemented through the time division mechanism.Therefore,the communication performance among VANET communication terminals mainly depends on the time synchronization among devices.This dissertation studies and designs the time synchronization method among VANET communication terminals.Moreover,we implement the time synchronization method by Linux-C programming to ensure and enhance the performance of network;2)According to the actual functional requirements of VANET communication terminal,we designed and developed the VANET communication terminal that meets the requirements.The main development work focuses on the debugging and porting of 802.11 p RF module and the design and implementation of the user graphic interface based on embedded Ubuntu + QT.3)The following experiments have been carried out on the developed VANET communication terminals:installation and commissioning of 802.1 1p RF module,data transmission and reception test,actual performance of time synchronization algorithm applied on VANET communication terminals,functional tests of main components of the system and operation experience of user graphical interface.