Abstract: The applications of WiFi technology have been gradually extended from the SOHO environment to outdoor mobile scenario, but meet with the problem of unreliable connection which is mostly caused by the nomadic scenario aimed scan mechanism. Hence the credibility of the scanning result record and its cost are studied, especially for the typical mobile scenarios of urban-road, highway, 250 km/h and 360 km/h railways, with the corresponding optimize strategies are put forward. Simulation results show that these strategies can achieve better credibility and lower cost in the typical mobile scenario with the implementation of wireless coverage taking into account, and then can provide a better AP（Access Point） switching decision and broadband data communication support for the onboard WiFi applications.

Key words: WiFi technology, scan, onboard, credibility, cost

摘要： WiFi技术已逐步由室内应用扩展到室外移动环境，但原本针对游牧式环境而设计的扫描策略尚难以为车载应用提供可靠的宽带连接，为此对WiFi在移动环境下的扫描记录可信度和扫描开销进行了深入探讨，并针对市区内、高速公路、250 km/h和360 km/h高速铁路等几种典型车载移动环境提出了相应的扫描策略优化方案。仿真结果表明，针对这几种典型车载移动环境设计的WiFi扫描策略在综合考虑无线信道部署方案的基础上，可达到较好的扫描记录可信度和较低的扫描开销，从而可为车载WiFi应用提供良好的AP切换判决和宽带数据通信支持。

关键词: WiFi技术, 扫描, 车载, 可信度, 开销