Evaluating Coverage Performance of NB-IoT in the ISM-band

The Narrowband Internet of Things (NB-IoT) is one of the premier access technologies adopted by many telecom operators as the next-generation IoT solution. This technology is primarily designed to tackle the rapid growth of low-power IoT applications. However, NB-IoT runs in licensed frequency bands leased by the conventional telecom operators and is usually very expensive. In this paper, we present a framework for evaluating the link-level performance of NB-IoT in the license-free radio spectrum, namely in the prominent 915 MHz band. The evaluation is performed using extensive physical layer emulation, including the effect of existing high-level interference recorded in this band. We report the resulting packet error rate with respect to the level of interference and different NB-IoT configurations. The results show promising feasibility of using the license-free spectrum to support NB-IoT enabled by the packet-repetition feature.