Ambient RF Energy Harvesting Sensor Device With Capacitor-Leakage-Aware Duty Cycle Control

In this paper, we present a software control method that maximizes the sensing rate of wireless sensor networks (WSNs) that are solely powered by ambient RF power. Unlike all other energy harvesting WSN systems, RF-powered systems present new challenges for energy management. A WSN node repeatedly charges and discharges at short intervals, depending on the energy intake. Typically in energy harvesting systems, a capacitor is used for energy storage because of its efficient charge and discharge performance and infinite recharge cycles. When the charging time is too short, a node is more likely to experience an energy shortage. On the contrary, if it is too long, more energy is lost because of leakage in the capacitor. In this paper, we introduce an adaptive duty cycle control scheme optimized for RF energy harvesting. This method maximizes the sensing rate by taking into account the leakage problem, a factor that has never been previously studied in this context. Our control scheme improves the efficiency by aggregate evaluation of operation reliability and leakage reduction.