Free Trial

Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.

Share this Page URL

Chapter 1: Introduction > Application Scenarios - Pg. 3

INTRODUCTION 3 As can be derived from Figure 1.1, LBSs are always context-aware services, because location is one special case of context information. In many cases, the concept of primary and secondary contexts can also be applied to LBSs, for example, when location data from different targets are related or the history of location data is analyzed to obtain high-level information such as the distance between targets or their velocity and direction of motion. Therefore, there is no sharp distinction between LBSs and context-aware services. And, in many cases context information that is relevant to a service, for example, information such as temperature, pollution, or audibility are closely related to the location of the target to be considered. Hence, its location must be obtained first before gathering other context information. A detailed introduction to the ideas and fundamentals of context-awareness is given in Dey and Abowd (1999) and Schmidt et al. (1999). LBSs can be classified into reactive and proactive LBSs. A reactive LBS is always explicitly activated by the user. The interaction between LBS and user is roughly as follows: the user first invokes the service and establishes a service session, either via a mobile device or a desktop PC. He then requests for certain functions or information, whereupon the service gathers location data (either of himself or of another target person), processes it, and returns the location-dependent result to the user, for example, a list of nearby restaurants. This request/response cycle may be repeated several times before the session is finally terminated. Thus, a reactive LBS is characterized by a synchronous interaction pattern between user and service. Proactive LBSs, on the other hand, are automatically initialized as soon as a predefined location event occurs, for example, if the user enters, approaches, or leaves a certain point of interest or if he approaches, meets, or leaves another target. As an example, consider an electronic tourist guide that notifies tourists via SMS as soon as they approach a landmark. Thus, proactive services are not explicitly requested by the user, but the interaction between them happens asynchronously. In contrast to proactive LBSs, where the user is only located once, proactive LBSs require to permanently track him in order to detect location events. In order to make the idea behind LBSs more clear, the following section presents a broad range of application scenarios. 1.2 Application Scenarios The scenarios presented here are subdivided into economical initiatives, which are carried out by operators and providers to raise the attractiveness of their networks and data ser- vices and thus to increase the average revenue per user, and public initiatives, which are introduced by governments for supporting or fulfilling sovereign or administrative tasks. 1.2.1 Business Initiatives The main motivation for offering LBSs is to gain revenue by increasing the average airtime per user, selling location information to third parties, and offering services tai- lored to the special needs of mobile users. A provider may either realize and offer LBSs on its own initiative or it may enter into business relationships with other actors, for example, from trade and commerce or the automobile industry, and realize and offer ser- vices on behalf of them. These relationships are defined by more or less complex business models, which are the subject of intensive research in the areas of business sciences