Mobile Tracking in 5G and Beyond Networks: Problems, Challenges, and New Directions

This paper explores mobile tracking as a privacy threat posed by 5G and beyond (5G&B) cellular networks. We reviewed the mobile network operation and protocol design, with a focus on the use of mobile identifiers and localization methods, as they are the key technical enablers of tracking and localization in mobile networks. We note that user location privacy against mobile network operators (MNO) is an extremely challenging problem. While a permanent identifier is the most critical piece of information to pinpoint a user and create linkability among records of a user, using a dynamic identifier presents significant privacy-utility challenges-many mobile applications and national security and emergency response services rely on the knowledge of mobile locations. At the same time, using an obfuscated version of a permanent identifier is only secure against outsider attackers, not the MNOs. We argue that, to protect user privacy against MNOs, a radically new design is necessary and such design must nullify any permanent identifiers to break record linkability and take into consideration of user anonymity, network utility (e.g., incoming call), user accountability, and user privacy awareness and control simultaneously. Lastly, we identify potential new directions as an initial attempt to tackle this challenging problem.