  Data aggregation is an effective solution to enable cellular support of
Internet-of-things (IoT) communications. Indeed, it helps alleviate channel
congestion, reduce the communication range, and extend battery-lifetime. In
this paper, we use stochastic geometry to analyze the performance of uplink
cellular IoT using different deployment strategies of aggregators, including
terrestrial and aerial ones, e.g., drones or unmanned aerial vehicles. We focus
on IoT-specific performance metrics, that are typically used by 3GPP.
Specifically, we derive closed-form expressions of the average transmit power
consumption, which is key to determine the lifetime of IoT devices, as well as
the maximum coupling loss, which is essential to determine the maximum coverage
the cellular system can support. Simulation results are presented to validate
the derived theoretical expressions. It is shown that aerial aggregators can
significantly extend the device lifetime and provide superior coverage compared
to other deployment strategies. In addition, random deployment performs well
when aggregators are densely deployed, whereas optimizing the location of a
single terrestrial aggregator is beneficial when devices are more clustered.
