Undervolting in WSNs — A feasibility analysis

The energy consumption of electric circuits depends on the applied voltage level. This is used by dynamic voltage scaling approaches where the voltage is lowered up to a datasheet specified level. To reduce the energy consumption even further, it would be possible to power the electric circuits below the specified voltage levels. Considering Wireless Sensor Nodes, this `undervolting' would save a substantial amount of energy and, hence, would lead to a significant longer lifetime of nodes and networks. Contrariwise, operating processors or nodes outside their specifications adds some extra incertitude to the system. In this paper, we analyze the effects of undervolting for a typical wireless sensor node in theory and practice. A prototype implementation is used to characterize the influence of lower-than-recommended voltage levels on the MCU. In addition, the impact of different temperatures is considered as well as the behaviour of an undervolted transceiver unit and, therefore, the effects on the wireless communication. While classical computer applications may contain too many hazards to outweigh the improved energy consumption when using undervolting, we show that it is particularly suitable for Wireless Sensor Networks (WSNs) with a huge potential of saving energy and the opportunity of novel power management approaches on every layer.