  It has been shown that ultra-narrow-band (uNB) massive machine type
communication using very compact devices with direct access to satellites is
possible at ultra low rate. This enables global ubiquitous coverage for
terminals without terrestrial service in the Internet of Remote Things and
provides access to any satellite up to the the geostationary earth orbit. The
lower data rate for waveforms providing uNB communication is set by the
stability and the phase noise of the applied oscillators. In this paper we
analyze the physical layer of two candidate waveforms, which are LoRa and
Unipolar Coded Chirp-Spread Spectrum (UCSS) with respect to phase noise and
oscillator frequency drifts. It is figured out that UCSS is more robust against
linear frequency drifts, which is the main source of error for uNB
transmissions.
