Wireless Sensor and Actuator Networks: Algorithms and Protocols for Scalable Coordination and Data Communication

10.5 COVERAGE MAINTENANCE BY ACTUATORS

It has not yet been well studied how to repair/maintain coverage using actuators. Existing solutions (Mei et al., 2007) are straightforward application of clustering and flooding with huge message overhead. They work under the assumption that actuators are carrying sufficient spare sensors. However, with this assumption, we can obtain a more efficient solution by combining face routing (Bose et al., 1999) and anycasting (Mitton et al., 2009). Below, we first introduce the previous work (Mei et al., 2007) and then describe the new solution.

10.5.1 Cluster-Based Approach

Mei et al. (2007) addressed how to replace failed sensors in WSAN by presenting three straightforward actuator coordination protocols. In a proposed centralized protocol, an actuator is appointed central manager and responsible for handling node failure reports. The central controller broadcasts its location to all sensors and other actuators. It maintains the latest position of each actuator by listening to actuator location updates. Sensors monitor each other and report detected node failures to the central manager, which then dispatches closest actuators to replace failed sensors with their carried spare ones. An actuator receiving multiple orders will handle them on a first-come-first-serve basis. As an actuator moves to its assigned failure location, it keeps updating the central manager with its latest position.

In a proposed distributed protocol, the sensory field is ...