Location Privacy Protection for Smartphone Users Using Quadtree Entropy Maps

The ever-increasing popularity of location-based services poses a serious threat to users’ location privacy. Most protection systems, however, rely on an anonymization server, which itself becomes one source of untrustworthiness. This article presents EMP2—a new location privacy protection scheme based on a quadtree entropy map, enabling the protection of users’ location privacy only with their smartphones. EMP2 accurately estimates the uncertainty of users' intended destinations and dynamically adjusts the protection level to defend against sophisticated inference attacks based on query correlation. Our evaluation demonstrates that EMP2 can effectively protect users’ location privacy with reasonable computation time and resource consumption.