A Wi-Fi direct system architecture for proximity-based applications

The widespread adoption of Wi-Fi made the need for easy, fast, and reliable ad-hoc networking much more critical. The Wi-Fi Direct standard provides a fast, stable, and secure connection which can be easily established between devices without requiring a wireless access point or an Internet connection. This is especially important as users of mobile phones can keep connection to several devices simultaneously without interrupting their Internet connection. Compared to Bluetooth, Wi-Fi Direct is more secure, operates at data rates of up to 250 Mbps, and covers distances up to 150 meters. We will give a short overview of Wi-Fi direct in general and then describe how it can be used for proximity-based applications such as ticketing systems, localized advertising and dynamic crowd management (e.g. football stadiums). The specialty of our implementation of Wi-Fi direct is that we utilize a star-like network. In this network, our server node works as the group owner in its center. All clients connect to the server node, which takes care of authentication, dynamic IP assignment and blacklisting. This architecture has also the advantage that it can be extended to service more clients by chaining server nodes together. In this paper, we describe the software components of our system and discuss the critical aspects of its design with respect to security, notification, and authentication. Finally, we compare our approach with other systems and investigate its limitations and differences.