Research On The Protection And Navigation System Of The Highway Running In Fog By ZigBee Technology Application

The highway running and management experience of all countries around the world shows that the fog is the most serious danger in the running of the highway in all unfavorable weather conditions. Nowadays, many kinds of measures are used to decrease or prevent the traffic accidents which are caused by fog. They are close highway, fog warnings and the automatic speed control system and the driver assistant system which is based on the technology of infrared ray, microwave and photography, etc. However, their shortcomings are obvious. Closing the highway will bring the loss of transportation and the inconvenience of going out. The installation and maintain of fog warnings and the speed control system will cost extremely much. If the driver assistant system based on the technology of infrared ray, microwave and photography were installed; all cars needed to be refitted and had to install this system. Thus this system is very difficult widely used in actual application. The main effect of the fog on the running safety of the highway is the low visibility. The low visibility influence the visible distance of drivers. The cars might stray from the traffic line because drivers could not identify the traffic condition. Then the traffic accidents happen or the rear-end accidents happen for the distance between the consequent two cars is less than the safe distance. Therefore, the protection and navigation system of the highway running in fog is researched and investigated to solve this problem. The system adopted GPS technology to provide drivers for traffic navigation, and use ZigBee wireless communication technology to realize the communication among cars. It offers the information of the distance between the consequent cars and the traffic condition. The system employed the embedded development technology, which could avoid the refit of cars.In recent years, with the fast development of the wireless technology network and the embedded system technology, the wireless communication network technology has advanced and been widely utilized in systems of wireless meter reading, wireless digital speech and intelligent transportation, etc. This dissertation integrative adopted ZigBee wireless communication technology, embedded technology and GPS location technology to construct the protection and navigation system of the highway running in fog. This dissertation briefly introduced the background of the project, the standard, the principle and the utilized area of the adopted technology. On the theoretical basis, the system hardware and software development platform and the environment were designed, focusing on the study and analysis of the requirements of the real-time system. MarKov chain model of mathematical analysis was constructed for the MAC layer unslotted CSMA/CA Algorithm of the ZigBee agreement. Some important parameters and their performance in this system were difficultly measured and assessed in the physical environment. In order to solve this problem, NS2 network simulation platform was used to testify this model, and to make simulation analysis on the important parameters. Therefore, the feasibility of the protection and navigation system of the highway running in fog was tested and verified further. The project is funded by Chongqing University Postgraduates science and Innovation Fund, Project Number: 200701Y1B0220208.