US Patent 9086499 Clustering protocol for directional sensor networks

A method and apparatus for tracking target objects includes a network of unidirectional sensors which correspond to nodes on the network. The sensors identify the presence of a target object, determine a first criteria for the relationship of the target object to the sensors and send a message to sensors neighboring the sensor. The message includes a unique identification of the target object and the first criteria. The sensors are ranked to determine which of the sensors should head a cluster of sensors for tracking the target object. Clusters are propagated and fragmented as the target object moves through a field of sensors.