Spontaneous privacy-friendly indoor positioning using enhanced WLAN beacons

Location based services pervade our lives more and more. Not only are outdoor movement of people and vehicles sensed via GPS, but with the use of wireless networks it is possible even indoors to locate people. On the one hand, this offers helpful and entertaining features, where GPS is not available; on the other hand, individual privacy is at risk with the unprotected release of highly sensitive location data. Many state of the art positioning methods require data exchange between the device and the network to enable positioning. Thus the users must implicitly reveal their current position to the network provider. In this paper, we address this problem and offer a new approach that allows users to ascertain their positions without exposing themselves to the network provider. Our approach embeds position data as information elements into IEEE 802.11 beacon frames, which are broadcasted periodically within each 802.11 basic service set. Based on this data, a mobile device can calculate its current position without revealing its presence to the network since beacons can be monitored passively. Finally we introduce a protocol that enables the transmission of necessary location data required by the positioning methods Fingerprinting and Proximity Sensing.