Date Added: Mar 2012
This paper explores a novel sleep scheduling method to reduce the delay of alarm broadcasting from any sensor node in WSNs. When a critical event occurs, an alarm message should be broadcast to the entire network. Specifically, there are two determined traffic paths for the transmission of alarm message, and level-by-level offset based wake up pattern according to the paths, respectively. When a critical event occurs, an alarm message is quickly transmitted along one of the traffic paths to center node, and then it is immediately broadcast by the center node along another path without collision.