An efficient approach for continuous density queries

Jie Wen*, Xiaofeng Meng, Xing Hao, Jianliang XU

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

4 Citations (Scopus)


In location-based services, a density query returns the regions with high concentrations of moving objects (MOs). The use of density queries can help users identify crowded regions so as to avoid congestion. Most of the existing methods try very hard to improve the accuracy of query results, but ignore query efficiency. However, response time is also an important concern in query processing and may have an impact on user experience. In order to address this issue, we present a new definition of continuous density queries. Our approach for processing continuous density queries is based on the new notion of a safe interval, using which the states of both dense and sparse regions are dynamically maintained. Two indexing structures are also used to index candidate regions for accelerating query processing and improving the quality of results. The efficiency and accuracy of our approach are shown through an experimental comparison with snapshot density queries.

Original languageEnglish
Pages (from-to)581-595
Number of pages15
JournalFrontiers of Computer Science in China
Issue number5
Publication statusPublished - Oct 2012

Scopus Subject Areas

  • Theoretical Computer Science
  • Computer Science(all)

User-Defined Keywords

  • continuous density queries
  • query efficiency
  • safe interval


Dive into the research topics of 'An efficient approach for continuous density queries'. Together they form a unique fingerprint.

Cite this