Counting Targets: Building and Managing Aggregates in Wireless Sensor Networks

Constructing and maintaining aggregates of sensors are key to many collaborative processing tasks for sensor networks such as tracking and localization. This paper defines a sensor aggregate as those nodes in a network that satisfy a grouping predicate. The parameters of the predicate depend on task and resource requirements. The paper develops a distributed protocol for constructing sensor aggregates in the context of counting distinct targets in a sensor field. Minimal assumptions about node onboard processing and communication capabilities are made so as to allow possible implementations on resource constrained hardware such as Berkeley wireless sensors (motes). Factors affecting protocol performance are discussed. The paper then presents simulation results showing how the protocol performance varies as key network and task parameters change, and provides an analytical analysis of the network behaviors consistent with the simulation results.