Continuous Quantile Query Processing in Wireless Sensor Networks
Johannes Niedermayer, Mário A. Nascimento, Matthias Renz, Peer Kröger, Hans‐Peter Kriegel · 2014
A major concern when processing queries within a wireless sensor network is to minimize the energy consumption of the network nodes, thus extending the networks lifetime. One way to achieve this is by minimizing the amount of communication required to answer queries. In this paper we investigate exact continuous quantile queries, focusing on the particular case of the median query. Many recently proposed algorithms determine a quantile by performing a series of refining histogram queries. For that class of queries, we recently proposed a cost-model to estimate the optimal number of histogram buckets within an algorithm for mini-mizing the energy consumption of a query. In this paper, we extend that algorithm for continuous queries. Furthermore we also offer a new refinement-based algorithm that employs a heuristic to minimize the number of message transmis-sions. Our experiments, using synthetic and real datasets, show that despite its theoretical runtime complexity our heuristic solution is able to perform significantly better than histogram-based approaches. 1.