Temporal Event Ordering with Fault Tolerance for Wireless Sensor and Actuator Networks

Temporal event ordering is an important issue in wireless sensor and actuator networks (WSAN) since actuators perform correct actions based on correct ordering among the time-related events. For temporal event ordering algorithms, they ensure that events captured from different sensors should be in the order. However, most of temporal ordering algorithms focus on the delay to transmit packets without considering the delay due to data loss. In the latter condition, the temporal ordering among events may be incorrect since some sensed data are lost due to the fail communication link or sensor. However, there is no literature for addressing the fault tolerance under the temporal event ordering of WSAN. Therefore, we propose a temporal event ordering with fault tolerance (TVOFT) in this paper. Differed from other temporal event ordering algorithms, TVOFT uses the routing table of each node with a acknowledge message once time to ensure the correct ordering of the time-related events. Therefore, the overhead of control packets also could be reduced in TVOFT. The simulations results demonstrate that TVOFT has the better correct event ordering rate and the less overhead of control packets than other temporal ordering algorithms even if the communication link or the sensor is fail.