A location privacy metric for V2X communication systems

The emerging vehicle-to-vehicle/vehicle-to-infrastructure (V2X) communication systems enable a new way of collaboration among the vehicles, the operators of transportation systems, and the service providers. However, many functionalities of V2X systems rely on detailed location information. This raises concerns on location privacy of the users of such systems. Although privacy protection mechanisms have been developed, existing privacy metrics are inappropriate or insufficient to reflect the true underlying privacy values in such systems. Without a proper metric, preserving location privacy in V2X communication systems becomes difficult due to the lack of a benchmark to evaluate any given protection mechanisms. In this paper, we develop a quantitative metric to measure and quantify location privacy in V2X systems. To do so, we introduce the concept of snapshots, which capture the information related to a user in a given space and time. Then the level of location privacy is quantified as the uncertainty of the information related to that user. Our analyses show that the metric provides the users, the system designers, and other stakeholders a valuable tool to evaluate the risk and measure the level of location privacy in V2X communication systems.