A Node's Life: Increasing WSN Lifetime by Dynamic Voltage Scaling

In mobile applications, like wireless sensor networks, it is often inevitable to use a location-independent source of energy. Wherever the batteries capacity or inefficient energy harvesting limits the lifetime, other solutions have to be implemented to increase the energy efficiency. Dynamic Voltage Scaling (DVS) is a well known technique with the ability to adapt the voltage level to the actual system load to save energy. While it has been used in many application areas, DVS has not been studied sufficiently for wireless sensor nodes. In this paper, we present a method to estimate the gain of DVS. We study DVS theoretically as well as in a practical manner, i.e., we using a prototype implementation of a DVS capable wireless sensor node. With the theoretical considerations we were able to optimize DVS for an 8-Bit ULP micro controller by a combination of DVS and dynamic power management (DPM). In addition, we proved the calculated results with an extensive practical evaluation of the concept using a prototypical implementation. Moreover, we analysed the effect of voltage scaling on other components of the sensor node (transceiver, sensors and memory).