Estimating the Benefit of Location-Awareness for Mobile Data Management Mechanisms Uwe Kubach and Kurt Rothermel Institute of Parallel and Distributed High-Performance Systems (IPVR), University of Stuttgart, Breitwiesenstr. 20-22, 70565 Stuttgart, Germany Uwe.Kubach@informatik.uni-stuttgart.de Abstract With the increasing popularity of mobile computing devices, the need to access information in mobile environments has also grown rapidly. In order to support such mobile information accesses, location-based services and mobile information systems often rely on location-aware data management mechanisms like location-aware caching, data dissemination or prefetching. As we explain in this paper, the location-awareness of such mechanisms is only useful, if the ac- cessed information is location-dependent, i.e. if the probability with that a certain information object is accessed depends on the user’s location. Although the location-dependency of the accessed information is crucial for the efficiency of location-aware data management mechanisms and the benefit they can get out of their location-awareness, no metric to measure the location-depen- dency of information has been proposed so far. In this paper, we describe such a metric together with a second one for a further important characteristic of mobile information accesses, the so-called focus. 1 Introduction Location-based services provide their users with local information depending on their current geographic position. For example, a user can ask for nearby restaurants or the shopping centers in his proximity. An important requirement for such location-based services to be beneficial is that the offered information is location-dependent, i.e. that the relevance of each information object for the user depends on his location. Such a location-dependency is not only exploited for the pre-selection of informa- tion in location-based services but also in many other data management mechanisms supporting mobile information systems. Since they consider a user’s location, these mechanisms are called location-aware. Examples are location-aware caching [11,5], dissemination [6], prefetching [4], and hoarding mechanisms [8]. So far, the location-dependency has been mostly considered as a binary character- istic of an information system, i.e. an information system respectively the information offered by the system was said to be location-dependent or not. However, we claim that there is a complete spectrum of mobile information systems, which differ in the degree of their location-dependency. This spectrum ranges from inherently location-dependent systems to location-independent systems with many nuances in between. In inherently location-dependent systems each information object belongs to a fixed location and is only accessed when the user is located there. An example for such a sys- 1