Over the last few years, the number of mobile devices connected to the CERN internal network has increased from a handful in 2006 to more than 10,000 in 2015. Wireless access is no longer a “nice to have” or just for conference and meeting rooms, now support for mobility is expected by most, if not all, of the CERN community. In this context, a full renewal of the CERN Wi-Fi network has been launched in order to provide a state-of-the-art Campus-wide Wi-Fi Infrastructure. Which technologies can provide an end-user experience comparable, for most applications, to a wired connection? Which solution can cover more than 200 office buildings, which represent a total surface of more than 400.000 m2, while keeping a single, simple, flexible and open management platform? The presentation will focus on the pre-studies which were done at CERN to review the full Wi-Fi infrastructure across the Campus. Moreover modern demands for Wi-Fi connectivity, as well as designing process of new CERN Wi-Fi network (RF planning, simulation, site survey) will be presented.