Dynamic Tracking of Composite Events in Wireless Sensor Networks

Tracking moving objects is one important feature of wireless sensor networks. It is of interest in intrusion detection, traffic monitoring, security applications, and environmental monitoring. Current approaches to event tracking either focus on ad-hoc solutions to track specific objects, or address specific sensors or transducers as sources of data. On the other hand, by addressing composite events as source of data, it is possible to obtain higher-level information that is computed cooperatively by the sensors themselves that aggregate and combine the low-level acquired data. To address tracking of composite event we propose a general approach based on query languages. Our proposal allows to express in a simple form the properties of the composite event to be tracked, and the attributes related to the tracked events that have to be reported to the user. We propose and an in-network query processing model that implements the language and that allows the sensors to track and collect data from a moving event in a dynamic and autonomous way. The results of simulation experiments show that the proposed approach allows to successfully track moving events by properly tuning some parameters of the system.