Fast alarm broadcasting in critical event monitoring using wireless sensor networks

In mission-critical applications such as battlefield reconnaissance or industrial safety and security, a large number of sensor nodes are deployed in a large area to detect and report event related information to the end-users. When a critical event in the monitoring region is detected by a node, alarm should be broadcast to all the other nodes in the neighborhood. As the sensor nodes are expected to work for a long time without recharging their batteries, a sleep scheduling is always used during the monitoring process. However, sleep scheduling will cause serious delays in large scale Wireless Sensor Networks (WSNs), because sensor nodes always have to wait for the receiver nodes to wake up before being able to transmit packets to them. Therefore, a delay-efficient sleep scheduling needs to be designed for critical event monitoring, which can guarantee low broadcasting delay for all the nodes in the network.