A Statistical Evaluation of Coherence Time for Non-Terrestrial Communications

Non-terrestrial networks (NTNs) are recognized as essential components of the next-generation communication systems. This letter evaluates the coherence time for non-terrestrial channels, revealing that the rapid mobility of non-terrestrial base stations (BSs) substantially diminishes channel coherence time. Our results demonstrate that the existence and enhancement of the line-of-sight channel play a crucial role in extending coherence time. Furthermore, unlike terrestrial networks, adjustments to receiver beamwidth seldom affect coherence time with a highspeed motion of the BS in NTNs.