A fault-tolerant model for wireless sensor-actor system

In a wireless sensor and actor network MAN), a group of sensors and actors are geographically distributed and linked by wireless networks. Sensors gather information sensed for an event in the physical world and send them to actors. Actors perform appropriate actions on actuation devices by making a decision on receipt of sensed information from sensors. Sensors are low cost, low powered devices with limited energy, computation, and wireless communication capabilities. Sensors may not only stop by fault but also suffer from arbitrary faults. Furthermore, wireless communication is less reliable due to noise and shortage of power of sensors. Reliable real time communication among sensors, actors, and actuation devices, is required in WSAN applications. We newly propose a multi-actor/multi-sensor (MAMS) model. In addition, multiple actors may perform actions on receipt of sensed information. Multiple redundant execution of an action on each device have to be prevented and conflicting actions on each device from multiple actors have to be serialized. In this paper, we discuss how to make WSAN reliable and available and how to reliably and non-redundantly perform actions with realtime constraints.