Linear Location-Based Services

Location-based services (LBS) support users during their mobile decision-making. T hey ar e i nformation services which are se nsitive t o their u ser’s location and r elate it to the surrounding environment, which in turn pro-vides l ocation-based information t o facilitate the successful completion of spatio-temporal tasks. Traditionally, LBS have been classified into different application areas [5]. We p ropose to d escribe LBS by t he d egrees o f f reedom t hey o ffer to their users in choosing the space-time path [6] while using the service. Two di-mensions are c onsidered: w hether or n ot an LBS offers th e freedom o f choosing 1) t he s patial t rajectory, and 2) the s peed o f l ocomotion. These lead to the following four categories (see also Table 1): A) Explorer LBS: t he u ser can f reely ch oose both, spatial t rajectory a nd speed. Most LBS fall into this category, such as pedestrian tourist guides where points of interest (POI) can be visited in arbitrary order. B) Flow LBS: the user can freely choose her trajectory, but not her speed. A car d river’s s peed, for ex ample, i s typically c onstrained by th e tra ffic flow, while there is usually more than one route option. Location-base