Another Outlier Bites the Dust: Computing Meaningful Aggregates in Sensor Networks

Abstract-- Recent work has demonstrated that readings provided by commodity sensor nodes are often of poor quality. In order to provide a valuable sensory infrastructure for monitoring applications, we first need to devise techniques that can withstand "dirty" and unreliable data during query processing. In this paper we present a novel aggregation framework that detects suspicious measurements by outlier nodes and refrains from incorporating such measurements in the computed aggregate values. We consider different definitions of an outlier node, based on the notion of a user-specified minimum support, and discuss techniques for properly routing messages in the network in order to reduce the bandwidth consumption and the energy drain during the query evaluation. In our experiments using real and synthetic traces we demonstrate that: (i) a straightforward evaluation of a user aggregate query leads to practically meaningless results due to the existence of outliers; (ii) our te...

• Type: Conference
• Year: 2009
• Where: ICDE
• Authors: Antonios Deligiannakis, Yannis Kotidis, Vasilis Vassalos, Vassilis Stoumpos, Alex Delis
• Keywords: Commodity Sensor Nodes, Computed Aggregate Values, Database, ICDE 2009, Outlier Nodes, User Aggregate Query, Valuable Sensory Infrastructure