Measurement-Based Investigations of the NB-IoT Downlink Performance in Fading Channels

The letter presents experimental results of investigations on the narrowband Internet of Things (NB-IoT) performance under two predefined multipath channel models, related to the reflections-free scenario of an unobstructed signal path. The NB-IoT downlink channel performance was systematically tested for resilience to the multipath propagation phenomenon (naturally occurring in real-life environments of IoT devices deployment), with the most robust modulation-coding scheme enforced, i.e., quadrature phase shift keying (QPSK) modulation without repetitions. Each of these three radio fading channels was artificially generated in electromagnetically isolated laboratory facilities. The NB-IoT equipment setup, the fading simulator for emulating the fading channels as well as the infrastructure that allowed obtaining desirable maximum coupling loss (MCL) values, were described along with the presentation of the measurement scenarios. Analysis of results led to the formulation of practical takeaways regarding the reduction in the maximum pathloss of a fading-free channel, in response to fadings incurred on the NB-IoT downlink signal by Extended Pedestrian-A (EPA) and Extended Typical Urban (ETU) channels.