The Design And Implementation Of Vehicular Central Navigation Terminal System Based On IPv6

With the rapid development of Chinese economy, the congestion of urban traffic has been brought into focus among people. The development of communication technology and the widely use of geographical information systems technology, Central navigation system has been brought into focus among the navigation, because it can relieve urban traffic congestion. The most difference between central navigation system and autonomous navigation system is that center navigation system provides real time and accurate navigation, according to road network information and road conditions. At the same time the navigation terminal system download map data through network from map data server, the terminal does not store the electronic map data and the complexity application of intelligent transportation systems. Only defines the center vehicle terminal and the navigation data exchange protocol, car navigation terminal will be a purely man-machine interface (HMI, Human Machine Interface), which greatly reduces the complexity of the design and implementation. Also, this design philosophy and the social development of China's current high-speed, fast network and roadside POI (Point of Interest) fit with the update, but if not handled properly on the center of the network delay will cause a lot of the effect of navigation.This paper studied central navigation terminal system based on IPv6 not only provides navigation services and information services, but it also can provide remote diagnose and repair function through the wireless network. Navigation system terminal map data download from the server, The Center navigation system needs to solve the biggest problem is that how ensure the terminal system get the map data in real time. This navigation device solves well the navigation effect of network transmission.First, this paper designed and implemented a map matching module, the necessary road network data is downloaded through the wireless network server in real time from the navigation center server. Designed road network data pre-fetch and update policies during network transmission based on the map block. The vehicle experiment test the feasibility of real-time map-matching downloading data service from a central network through the wireless network. Second, this map designed and implemented the navigation guide function, it downloads data (local amplification data and path planning data) by the network, guide user according to real-time traffic, provide user road path planning function. Third, this paper designed and implemented the map display function is an important function, in order to ensure the real-time map display, chooses to use the map block storage and the secondary cache data to improve transfer and display map graphic efficiency. It design navigation center server and the terminal graphical data communication protocol and the terminal store graphics data structure, the system achieves effective e-map data which includes real-time navigation information transmission between the terminal and the server. To meet the ream-time demand of the e-map updating in the terminal, it put forward an online e-map data pre-fetch and updating strategy. Simulation and test-bed test both show that the system can achieve good online and real-time e-map distribution by using CDMA.