Event Query Processing Based on Data-Centric Storage in Wireless Sensor Networks

When wireless sensor networks are employed for event monitoring, such as fire detection and enemy movement monitoring, the observers are more interested in the monitored events rather than the readings from sensors. To answer event queries such as "Where was the fire detected during 2-6pm?", an energy-efficient query processing technique is required. This paper presents a data-centric storage strategy, called CM-DCS, and also proposes two distributed event query processing algorithms. Furthermore, the energy consumptions for query processing methods based on three kinds of storage strategies namely external storage, local storage and CM-DCS are analyzed and compared, so that users can have a guideline of choosing a correct storage strategy for different applications. Theoretical analysis and simulation results show that the event query processing algorithm based on CM-DCS can save more energy than those algorithms based on the external storage strategy and the local storage strategy in most cases.