Privacy-aware and energy-efficient geofencing through reverse cellular positioning

Location-based services (LBSs) are gaining a significant increase in popularity these days and are about to take the next step towards proactive LBSs. In comparison to conventional LBSs, their proactive variant makes use of continuous position tracking to detect changes in spatial relationships between a user and surrounding objects and proactively perform according actions, a concept that is also known as geofencing. But tracking so far also results in tremendous battery drain in mobile devices and may conceal serious privacy issues for their users which can be seen as the biggest inhibitors to making proactive LBSs available for the masses. This paper proposes a method to detect the relationship between a user and a target location without significant overhead in power consumption by exploiting signals broadcasted from cellular radio network infrastructure at that location. In opposite to conventional cellular location determination mechanisms like WiFi or Cell-Id positioning where a radio beacon will be resolved as soon as it is detected, our proposal has to resolve only one request initially. This not only saves energy, but also preserves the user´s privacy since no consecutive requests have to be sent to a location lookup server, for translating radio beacons into locations. Instead, the radio beacons that can be detected at the target location will be queried once and afterwards only compared to the currently received cellular radio signals. In some outlying areas only rudimentary cellular coverage might be provided, which leads to inaccurate positioning. In that case, the method can still serve as a basis mechanism to further improve accuracy by shortly utilizing additional positioning methods like GPS. Relying on an almost global wireless data connectivity, smartphones can access data from the internet almost anywhere, which allows this approach to be broadly available as an energy-efficient and privacy-aware alternative to conventional cellular location d- termination.