  One of the main challenges when designing a new self-powered wireless sensor
network (WSN) technology is the vast operational dependence on its scarce
energy resources. Therefore, a thorough identification and characterisation of
the main energy consumption processes may lay the foundation for developing
further mechanisms aimed to make a more efficient use of devices' batteries.
This paper provides an energy consumption model for IEEE 802.11ah WLANs
operating in power saving mode, which are expected to become one of the
technology drivers in the development of the Internet of Things (IoT) in the
next years. Given the network characteristics, the presented analytical model
is able to provide an estimation of the average energy consumed by a station as
well as to predict its battery lifetime. Once the model has been validated, we
use it to obtain the optimal IEEE 802.11ah power saving parameters in several
IoT key scenarios, validating that the parameters provided by the IEEE 802.11ah
Task Group are already a very good choice.
