A wireless propagation analysis for the frequency of the pseudonym changes to support privacy in VANETs

Vehicle Ad Hoc Networks (VANETs) in Cooperative Intelligent Transport Systems (C-ITS) are based on the exchanges of messages among ITS-Stations (e.g., vehicles and roadside infrastructure) using the wireless G5 Dedicated Short Rate Communication (DSRC) standard to support safety-critical applications. VANETs require the authentication of ITS-stations and messages but the privacy of the drivers of the vehicles must be supported. In recent years, researchers have proposed solutions to mitigate privacy risks based on the use of pseudonyms. A key design decision is related to the frequency of the change of pseudonyms. The activity of a vehicle under one pseudonym can be linked to another thus providing traceability of the vehicle and a privacy risk for the driver. To prevent link-ability of actions, the vehicle must change pseudonyms over time. In this paper, the authors propose a radio frequency physical layer analysis to determine the frequency of the pseudonym changes. The rationale is that different wireless propagation conditions will impact the capability of the privacy attacker to trace the vehicle, thus reducing the need to frequently change the pseudonyms. The analysis has been performed in different channel fading conditions and for different relative speed values.