Updating and Querying Databases that Track Mobile Units

  • Authors:

  • Ouri Wolfson;A. Prasad Sistla;Sam Chamberlain;Yelena Yesha

  • Affiliations:

  • Department of Electrical Engineering and Computer Science, University of Illinois, Chicago, IL 60607. wolfson@eecs.uic.edu;Department of Electrical Engineering and Computer Science, University of Illinois, Chicago, IL 60607. sistla@eecs.uic.edu;Army Research Laboratory, Aberdeen Proving Ground, MD;Center of Excellence in Space Data and Information Sciences at NASA, Goddard Space Flight Center, Greenbelt, MD

  • Venue:
  • Distributed and Parallel Databases - Special issue on mobile data management and applications
  • Year:
  • 1999

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Abstract

In this paper, we consider databases representing information about moving objects(e.g., vehicles), particularly their location.We address the problems of updating and querying suchdatabases. Specifically, the update problem is to determine whenthe location of a moving object in the database (namely itsdatabase location) should be updated. We answer this question by proposing an information cost model that captures uncertainty, deviation, and communication.Then we analyze dead-reckoning policies, namely policies that update the database location whenever the distancebetween the actual location and the database location exceeds agiven threshold, x.Dead-reckoning is the prevalent approach in military applications,and our cost model enables us to determine the threshold x.We propose several dead-reckoning policies and we compare theirperformance by simulation.Then we consider the problem of processing range queriesin the database. An example of a range query is ‘retrieve the objects thatare currently inside a given polygon P′. We propose a probabilisticapproach to solve the problem. Namely, the DBMS will answersuch a query with a set of objects, each of which is associatedwith a probability that the object is inside P.