Swing & swap: user-centric approaches towards maximizing location privacy

In wireless networks, the location tracking of devices and vehicles (nodes) based on their identifiable and locatable broadcasts, presents potential threats to the location privacy of their users. While the tracking of nodes can be mitigated to an extent by updating their identifiers to decorrelate their traversed locations, such an approach is still vulnerable to tracking methods that utilize the predictability of node movement to limit the location privacy provided by the identifier updates. On the other hand, since each user may need privacy at different locations and times, a user-centric approach is needed to enable the nodes to independently determine where/when to update their identifiers. However, mitigation of tracking with a user-centric approach is difficult due to the lack of synchronization between updating nodes. This paper addresses the challenges to providing location privacy by identifier updates due to the predictability of node locations and the asynchronous updates, and proposes a user-centric scheme called Swing that increases location privacy by enabling the nodes to loosely synchronize updates when changing their velocity. Further, since each identifier update inherently trades off network service for privacy, the paper also introduces an approach called Swap, which is an extension of Swing, that enables the nodes to exchange their identifiers to potentially maximize the location privacy provided by each update, hence reducing the number of updates needed to meet the desired privacy levels. The performance of the proposed schemes is evaluated under random and restricted pedestrian mobility.