Optimization of Quality of Service in Wireless Sensor Networks Powered by Solar Cells

Sensors equipped with solar cells and rechargeable batteries are useful in many outdoor, long-lasting applications. In these sensors the cycles of energy harvesting and battery recharge need to be managed appropriately in order to avoid sensor unavailability due to energy shortages. We suggest that adapting the sensor duty cycle (and specifically its environment sampling frequency) to the expected energy production and residual battery charge is very useful to avoid sensors unavailability. To this purpose we introduce a novel concept of QoS, which is measured in terms of sampling frequency, and we provide a mean to maximize the QoS, i.e. the extent of the period in which the sensor operates at the user´s desired sampling frequency.