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Issue No. 10 - October (2011 vol. 23)
ISSN: 1041-4347
pp: 1513-1525
Baljeet Malhotra , University of Alberta, Edmonton
Mario A. Nascimento , University of Alberta, Edmonton
Ioanis Nikolaidis , University of Alberta, Edmonton
In this paper, we consider the exact top-k query problem in wireless sensor networks, i.e., where one seeks to find the k highest reported values as well as the complete set of nodes that reported them. Our primary contribution in this context is EXTOK, a provably correct and topology-independent new filtering-based algorithm for processing exact top-k queries. As a secondary contribution we confirm a previous result of ours by showing that the efficiency of top-k query processing algorithms, including EXTOK, can be further improved by simply choosing a proper underlying logical tree topology. We examine EXTOK's performance with respect to a number of parameters and different logical tree topologies while using both synthetic and real data sets. Our simulation reveal that EXTOK consistently outperforms the current state-of-the-art algorithm by a very significant margin and regardless of the underlying logical tree topology.
Wireless sensor networks, top-k query processing, in-network query processing, energy efficiency.

I. Nikolaidis, B. Malhotra and M. A. Nascimento, "Exact Top-K Queries in Wireless Sensor Networks," in IEEE Transactions on Knowledge & Data Engineering, vol. 23, no. , pp. 1513-1525, 2010.
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