Privacy in Location-Based Services: State-of-the-Art and Research Directions

The explosive growth of location-detection devices (e.g., GPS-like devices and handheld devices) along with wireless communications and mobile databases results in realizing location-based applications that deliver specific information to their users based on their current locations. Examples of such applications include location-based store finder, location-based traffic reports, and location-based advertisements. Although location-based services promise safety and convenience, they threaten the privacy and security of users as such services explicitly require users to share private location information with the service. If a user wants to keep her location information private, she has to turn off her location-aware device and temporarily unsubscribe from the service. Recent studies show that such privacy concerns - ranging from worries over employers snooping on their workers' whereabouts to fears of tracking by potential stalkers - are a serious obstacle to wider adoption of location-based services. This article aims to provide practitioners, researchers, and graduate students with the state of the art and major research issues in the important and practical research area of location privacy. In general, the tutorial is divided into the following five parts: (1) legislative issues and privacy concerns, (2) location privacy in mobile environments, (3) privacy attack models, (4) privacy-aware location query processing; (5) concluding remarks.