  Due to the increase of Internet-of-Things (IoT) devices, IoT networks are
getting overcrowded. Networks can be extended with more gateways, increasing
the number of supported devices. However, as investigated in this work, massive
MIMO has the potential to increase the number of simultaneous connections,
while also lowering the energy expenditure of these devices. We present a study
of the channel characteristics of massive MIMO in the unlicensed sub-GHz band.
The goal is to support IoT applications with strict requirements in terms of
number of devices, power consumption, and reliability. The assessment is based
on experimental measurements using both a uniform linear and a rectangular
array. Our study demonstrates and validates the advantages of deploying massive
MIMO gateways to serve IoT nodes. While the results are general, here we
specifically focus on static nodes. The array gain and channel hardening effect
yield opportunities to lower the transmit-power of IoT nodes while also
increasing reliability. The exploration confirms that exploiting large arrays
brings great opportunities to connect a massive number of IoT devices by
separating the nodes in the spatial domain. In addition, we give an outlook on
how static IoT nodes could be scheduled based on partial channel state
information.
