Sense-And-Trace: A Privacy Preserving Distributed Geolocation Tracking System.

The capabilities of modern smartphones pave the way for a new collaborative usage of this technology. Several researchers already envisaged to use this technology for distributed sensing purposes. In particular, one of these purposes focuses on tracing devices (people) movement. Current solutions for distributed tracing (either based on information provided by the mobile nodes, or collected by the surrounding network) have some limitations: e.g. accuracy, privacy, cost of deployment, and cost of operation. The aim of this paper is to highlight the open problems of distributed geolocation tracing and to propose a solution for some of the current problems. In particular, we propose Sense-And-Trace (SAT), which is a system that makes use of collaborative sensing to collect information about other mobile nodes with the final aim of tracking potential target nodes. In SAT, information is collected in a way such that the privacy of nodes that voluntarily collaborate is preserved, and the information of the mobility of a node is disclosed only to the authorized entity (e.g. a law enforcement agency with the appropriate permission). Our solution can be seen as an enhancement of the classical "neighborhood watching" concept, with fine-grained mobility information automatically-collected through the devices carried by humans.