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Semantic Caching in Location-Dependent Query Processing

  • Baihua Zheng
  • Dik Lun Lee
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2121)

Abstract

A method is presented in this paper for answering location-dependent queries in a mobile computing environment. We investigate a common scenario where data objects (e.g., restaurants and gas stations) are stationary while clients that issue queries about the data objects are mobile. Our proposed technique constructs a Voronoi Diagram (VD) on the data objects to serve as an index for them. A VD defines, for each data object d, the region within which d is the nearest point to any mobile client within that region. As such, the VD can be used to answer nearest-neighbor queries directly. Furthermore, the area within which the answer is valid can be computed. Based on the VD, we develop a semantic caching scheme that records a cached item as well as its valid range. A simulation is conducted to study the performance of the proposed semantic cache in comparison with the traditional cache and the baseline case where no cache is used. We show that the semantic cache has a much better performance than the other two methods.

Keywords

mobile computing location-dependent query Voronoi Diagrams 

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References

  1. 1.
    D. Barbara. Mobile computing and databases-a survey. IEEE Transactions on Knowledge and Data Engineering, 11(1), January-February 1999.Google Scholar
  2. 2.
    Budiarto, K. Harumoto, M. Tsukamoto, and S. Nishio. Position locking: Handling location dependent queries in mobile computing environment. In Proceeding of the Wordwide Computing and Its Applications, 1997.Google Scholar
  3. 3.
    M. de Berg, M. van Kreveld, M. Overmars, and O. Schwarzkopf. Computational Geometry: Algorithms and Applications, chapter 7. Springer-Verlag, 2000.Google Scholar
  4. 4.
    H. G. Gök. Processing of continuous queries from moving objects in mobile computing systems. Master’s thesis, Bilkent University, 1999.Google Scholar
  5. 5.
    H. G. Gök and O. Ulusoy. Transmission of continuous query results in mobile computing systems. Information Sciences, 125, 2000.Google Scholar
  6. 6.
    G. Kollios, D. Gunopulos, and V. J. Tsotras. Nearest neighbor queries in a mobile environment. In International Workshop on Spatio-Temporal Database Management, September 1999.Google Scholar
  7. 7.
    G. Kollios, D. Gunopulos, and V. J. Tsotras. On indexing mobile objects. In 18th ACM SIGMOD-SIGACT-SIGART Symp. on Principles of Database Systems, May 1999.Google Scholar
  8. 8.
    M. Nascimento and Y. Theodoridis. Benchmarking spatial-temporal databases: The gstd software. http://www.cti.gr/RD3/GSTD/.
  9. 9.
    Q. Ren and M. H. Dunham. Semantic caching in mobile computing. Submitted, under revision, 2000.Google Scholar
  10. 10.
    Q. Ren and M. H. Dunham. Using semantic caching to manage location dependent data in mobile computing. In The Sixth Annual International Conference on Mobile Computing and Networking, August 2000.Google Scholar
  11. 11.
    H. Schwetman. Csim User’s Guide (version 17). MCC Corporation, 1992.Google Scholar
  12. 12.
    Jonathan Richard Shewchuk. Triangle: A two-dimensional quality mesh generator and delaunay triangulator. http://www.cs.cmu.edu/quake/triangle.html.
  13. 13.
    P. Sistla, O. Wolfson, S. Chamberlain, and S. Dao. Modeling and querying moving objects. In Thirteenth International Conference on Data Engineering, April 1997.Google Scholar
  14. 14.
    P. Sistla, O. Wolfson, S. Chamberlain, and S. Dao. Querying the Uncertain Position of Moving Objects, pages 310–337. Springer Verlag, 1998.Google Scholar
  15. 15.
    J. L. Xu, X. Y. Tang, D. L. Lee, and Q. L. Hu. Cache coherency in location-dependent information services for mobile environment. In The First Conference on Mobile Data Management, December 1999.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2001

Authors and Affiliations

  • Baihua Zheng
    • 1
  • Dik Lun Lee
    • 1
  1. 1.Department of Computer ScienceHong Kong University of Science and TechnologyClear Water BayHongKong

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