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Abstract.Tracking is an enabling technology for many location based services. Given that the location of a moving object changes continuously but the database cannot be updated continuously, the research issue is how to accurately maintain the current location of a large number of moving objects while minimizing the number of updates. The traditional approach used in existing commercial transportation systems is for the moving object or the cellular network to periodically update the location database; e.g. every 2 miles. We introduce a new location update policy, and show experimentally that it is superior to the simplistic policy currently used for tracking; the superiority is up to 43% depending on the uncertainty threshold. We also introduce a method of generating realistic synthetic spatio-temporal information, namely pseudo trajectories of moving objects. The method selects a random route, and superimposes on it speed patterns that were recorded during actual driving trips.

Abstract. In this paper we examine the dissemination of reports about resources in mobile networks with hotspots, where hotspots, vehicles and sensors communicate with each other via short-range wireless transmission. Each disseminated report represents information about a spatial-temporal event, such as the availability of a parking slot at a particular time or the detection of an injured in an earthquake damaged building. We propose an opportunistic dissemination paradigm, in which a moving object transmits the reports it carries to encountered peers and obtains new reports in exchange. We address two issues in such an environment. First, we develop an architecture that allows a moving object to receive resource reports opportunistically. Second, we study how the received reports are used by a consumer to reduce resource discovery time. The proposed system has the potential to create a completely new information marketplace.

Abstract. In this paper we examine the benefit of reports about resources in mobile ad-hoc networks. Each disseminated report represents information about a spatio-temporal event, such as the availability of a parking slot or a cab request. Reports are disseminated by a peer-to-peer broadcast paradigm, in which an object periodically broadcasts the reports it carries to encountered objects. We evaluate the value of resource information in terms of how much time is saved when using the information to discover resources, compared to the case when the information is not used.

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