Sleep Schedule for Fast and Efficient Control of Parameters in Wireless Sensor-Actor Networks

Wireless sensor-actor networks can provide remote sensing and actuation services in a variety of applications. Depending on the application, the network should rapidly respond to critical variations in sensor input and take appropriate control action by the actor nodes without any delay. In order to prolong the lifetime of sensor networks, energy saving is done using sleep scheduling algorithms. Though the existing methods save energy, they lead to a large increase in end-to-end latency, which affects the efficiency of the sensor-actor network that requires fast control action. We propose a novel sleep schedule for the radio of the nodes for fast and efficient control of parameters (SEC) in sensor-actor networks with a semi-automated architecture that require minimum latency. During normal operation, the sensor nodes sense the parameters periodically using a static schedule. If the value of any parameter exceeds the set point the sink calculates the error signal and the sleep schedule is changed dynamically to activate the actor nodes in the area of interest. The corresponding sensor-actor nodes are made completely active till the error signal becomes zero, i.e. till the parameters are brought within the set point. The objectives of our protocol are to (1) minimize the latency in controlling the parameters by activating the actor nodes for the appropriate duration using the dynamic schedule (2) reduce the energy consumption by activating the neighboring sensor-actor nodes completely, only when parameters exceed the set point. Simulation results show that SEC protocol performs better than S-MAC by providing nearly 80% low latency with minimum energy consumption