14 The dimensions of locational privacy

Mutual advancements in wireless communications and geospatial technologies are creating real-time, pervasive tracking environments capable of capturing detailed information about individual activities in space and time. These advances will potentially provide benefits for individuals, researchers and commercial interests. Among the more exciting possibilities are location-based services (LBS). LBS are information services dependent upon the geographic location of users to deliver spatially adaptive content such as maps, routing instructions and friend finding (Hjelm, 2002; Schiller and Voisard, 2004; Küpper, 2005). Common applications include emergency response, personal navigation assistance, fleet management and recreation. LBS may also serve as a mechanism for collecting disaggregate activity-travel data from an unprecedented number of individuals, providing social scientists and planners detailed information regarding spatiotemporal patterns of mobility, activity participation and social interaction in urban environments (Dykes and Mountain, 2003; Miller, 2005b; Mountain, 2005). However, the development of ubiquitous location sensing creates serious concerns for individual location privacy. Information privacy generally refers to the claim that individuals should have control over the information collected about them (Westin, 1967). Reductions in personal information privacy are generally a product of two types of innovations: innovations for observing information about people and innovations for sharing this information with others. For LBS, users are mobile and are located through the presence of location-aware devices, often wireless cellular telephones. These devices obtain detailed positional estimates for individuals and distribute this information to a broader network through established communication protocols. If positional estimates are sampled with frequent regularity, movement traces are created identifying all locations visited by individuals in space and time. Given the increasing distributed nature of information services, these observed locations may be transferred among multiple entities within the context of a single transaction.