Date Added: Feb 2010
Wireless Sensor - Actuator Networks (WSANs) greatly enhance the existing wireless sensor network architecture by introducing powerful and possibly even mobile actuators. The actuators work with the sensor nodes, but can perform much richer application-specific actions. To act responsively and accurately, an efficient and reliable reporting scheme is crucial for the sensors to inform the actuators about the environmental events. Unfortunately, the low-power multi-hop communications in a WSAN are inherently unreliable; frequent sensor failures and excessive delays due to congestion or in-network data aggregation further aggravate the problem.