A Preliminary Study on Uncertainty of NB-IoT Measurements in Reverberation Chambers

New protocols related to internet-of-things applications may introduce previously unnoticed measurement effects due to the narrowband nature of these protocols. Such technologies also require less loading to meet the coherence bandwidth conditions, which may lead to higher variations accross the channel. This can cause a need to take additional components into account in the assessment of uncertainty. In this work, we present a preliminary study on uncertainties of NB-IoT measurements in reverberation chambers. We show a need to account for both the number of mode-stirring samples and the lack of spatial uniformity in the uncertainty analysis, where the latter generally dominates for wireless testing. We provide preliminary results for the uncertainty including both effects. We introduce a hypothesis for the effects of loading on the uncertainty, introducing that there may be an optimal loading point to minimize uncertainty, where we describe that this decision may not depend only on coherence bandwidth, but also on the number of significant modes.