Research On Fast Switching Technology Between APs Based On Vehicle Embedded WiFi

With the rapid development of mobile Internet, people have more and more high demand for fast access to the Internet in a mobile environment. The development of WiFi technology has become increasingly mature. In view of widespread application and low cost of WiFi,it has become one of potential ideal technologies of the broadband fast access to the Internet in a mobile environment But because of its own problem of existence horizon access and access being not stable in nomadic environment, the need for the further optimization and improvement so that it can provide broadband access stable for mobile environment. Therefore, this paper has a comprehensive and systematic study of the switching and scanning mechanism of WiFi in typical mobile environments.Firstly, this paper illustrates the WiFi technology, mainly including the characteristics of WiFi technology, development status, development and research status of WiFi technology in vehicle access. Besides, this paper introduces the domestic and foreign development and research status of AP fast switching, systematic analysis of the WiFi switching process and puts forward to the analysis of fast switching model based on multi-wireless module.Then, analyzes the core problems in the scanning process. The scanning mechanism in the urban environment (50km/h), highway(110km/h),high-speed railway (200km/h) and high-speed railway (300km/h) of several mobile environment have been studied deeply. The results show that:in the urban road (50km/h) environment, can be deployed11channel or the deployment of3orthogonal channels, and the scanning time interval corresponding design respectively for260ms and180ms; highway (110km/h) environment, and can be deployed in2to3orthogonal channels, scanning interval is100ms; high speed rail (200km/h) environment, and can be deployed in2orthogonal channels, the corresponding design scanning interval is60ms; high-speed railway (300km/h) environment, and can be deployed in1channels, the design interval scanning time of20ms.Finally, this paper sets up the WiFi scanning experiment platform based on multi-wireless module, developes scanning control of main control program Handoff, studies the driver program of the wireless module and optimizes the scanning time interval parameter and does the scanning experiment on this basis the fixed and the speed of mobile environment40km/h,60km/h and80km/h, the experimental results show that can guarantee the mobile environment scanning and recording the credibility through the optimization of scanning parameters, and scanning interval were not more than1s,0.5s and0.25s in three different speeds of40km/h,60km/h and80km/h in the mobile environment.