Robust Aggregation in Sensor Networks

In the emerging area of sensor-based systems, a significant c hallenge is to develop scalable, fault-tolerant methods to extract useful information from the data the sensors coll ect. An approach to this data management problem is the use of sensor "database" systems, which allow users to perfo rm aggregation queries on the readings of a sensor network. Due to power and range constraints, centralized ap proaches are generally impractical, so most systems use in-network aggregation to reduce network traffic. Howev er, these aggregation strategies become bandwidth- intensive when combined with the fault-tolerant, multi-pa th routing methods often used in these environments. In order to avoid this expense, we investigate the use ofapproximate in-network aggregation using small sketches and we survey robust and scalable methods for computing dupl icate-sensitive aggregates.