City University of New York
Data gathering or convergecast in wireless sensor networks is a many-to-one communication pattern in which sensors send data to a base station or sink. Each sensor node operates as a data source and/or relay node to pass along data items. A routing tree, specifying paths from all source nodes to the sink, is derived from the connectivity graph of the underlying network. Data at each sensor node is forwarded on to the parent within the tree, until reaching the root, i.e., the sink.