  This paper proposes an ultra-reliable device-centric uplink (URDC-UL)
communication scheme for airborne networks. In particular, base stations (BSs)
are mounted on unmanned aerial vehicles (UAVs) that travel to schedule UL
transmissions and collect data from devices. To attain an ultra-reliable
unified device-centric performance, the UL connection is established when the
UAV-BS is hovering at the nearest possible distance from the scheduled device.
The performance of the proposed URDC-UL scheme is benchmarked against a
stationary UAV-centric uplink (SUC-UL) scheme where the devices are scheduled
to communicate to UAV-BSs that are continuously hovering at static locations.
Utilizing stochastic geometry and queueing theory, novel spatiotemporal
mathematical models are developed, which account for the UAV-BS spatial
densities, mobility, altitude, antenna directivity, ground-to-air channel, and
temporal traffic, among other factors. The results demonstrate the sensitivity
of the URDC-UL scheme to the ratio between hovering and traveling time. In
particular, the hovering to traveling time ratio should be carefully adjusted
to maximize the harvested performance gains for the URDC-UL scheme in terms of
link reliability, transmission rate, energy efficiency, and delay. Exploiting
the URDC-UL scheme allows IoT devices to minimize transmission power while
maintaining unified reliable transmission. This preserves the device's battery
and addresses a critical IoT design challenge.
