Mobile Intelligence

19.2 RELATED WORK

Works related to location privacy techniques can be categorized into three main classes: anonymity-based, obfuscation-based, and policy-based.

Anonymity-based techniques provide solutions for the protection of the identities of the users. This class includes all solutions based on the notion of anonymity [10, 12, 19, 23], which is aimed at making an individual (i.e., her identity or personal information) not identifiable. Beresford and Stajano [10, 11] propose a method, called mix zones, based on an anonymity service that delays and reorders messages from subscribers within predefined zones. The proposal is based on a trusted middleware that lies between the positioning systems and the third-party applications and is responsible for limiting the information collected by applications. The mix zones model introduces the concepts of application zones, which are homogeneous application interested located in a specific geographic area, and mix zones, which represent areas where a user cannot be tracked. In particular, within mix zones, a user is anonymous in the sense that the identities of all users coexisting in the same zone are mixed and become indiscernible. The mix zones model is aimed at protecting long-term user movements still allowing the interaction with many location-based services. Other works [19, 23] are based on the concept of location k-anonymity, meaning that a user is indistinguishable from other k − 1 users in a given location area or temporal interval. ...