Continuous probabilistic count queries in wireless sensor networks

Abstract

Count queries in wireless sensor networks (WSNs) report the number of sensor nodes whose measured values satisfy a given predicate. However, measurements in WSNs are typically imprecise due, for instance, to limited accuracy of the sensor hardware. In this context, we present four algorithms for computing continuous probabilistic count queries on a WSN, i.e., given a query Q we compute a probability distribution over the number of sensors satisfying Q's predicate. These algorithms aim at maximizing the lifetime of the sensors by minimizing the communication overhead and data processing cost. Our performance evaluation shows that by using a distributed and incremental approach we are able to reduce the number of message transfers within the WSN by up to a factor of 5 when compared to a straightforward centralized algorithm. © 2011 Springer-Verlag.