An energy management method of sensor nodes for environmental monitoring in Amazonian Basin

In this paper we specifically address the constraint of energy consumption related to wireless sensor networks deployed at remote regions where the geographical access is complicated and consequently the maintenance routines seldom occurs. This research proposes an energy management method for environmental monitoring at the Amazonian Basin, where the interval between maintenance routines is greater than 6 months and the geographical location constrains the access to the sensor nodes. The proposed method is based on the duty cycling technique and aims to extend the sensor node lifespan in case of its external power source fails or its power consumption increases due to damages in sensor node devices. The management energy algorithm embedded into the sensor node employs the Shepherd Equation to simulate curves of battery discharge for each power consumption condition and thus it enables to estimate accurately the lifespan of a sensor node. Therefore, the sensor node is aware of its available energy and was programmed to react to it by switching between predefined operating modes to save energy and prolong as much as possible its lifespan. The Sensor Energy Management Method (SEMM) ensures that sensor nodes are operational throughout maintenance periods so that at least data acquisition tasks are performed to guarantee historical data sets essential to hydrological forecasts. A sensor node prototype was built and the SEMM was validated by a number of indoors experiments. The sensor node lifetime was increased by 20 % when the proposed method was compared to a conventional energy use.