On query processing in wireless sensor networks using classes of quality of queries

This paper introduces the concept of quality of queries (QoQs) towards a more adaptive query processing in wireless sensor networks (WSNs). This approach aims at the intelligent consumption of the limited resources (energy and memory) available in these networks while still delivering a reasonable level of data quality as expected by client applications. In a nutshell, the concept of QoQ stipulates that the results of different queries injected into the same WSN can be tailored according to different criteria, in particular the levels of query result accuracy and energy consumption. For this purpose, four classes of QoQ (CoQoQ) are specified having in mind distinct requirements in terms of these criteria. To allow the implementation of these classes in a real WSN setting, a new novelty-detection based algorithm, referred to as AdaQuali (which stands for “ADAptive QUALIty control for query processing in WSN”), is also proposed in a manner as to control the sensor node activities through the dynamic adjustment of their rates of data collection and transmission. In order to validate the novel approach, simulations with a prototype implemented in Sinalgo have been conducted over real temperature data. The results achieved evidence the suitability of the proposal and point to gains of up to 66.76%, for different CoQoQ, in terms of reduction in energy consumption.