On the Random Access Procedure of NB-IoT Non-Terrestrial Networks

The standardization of the 5G systems has recently entered in an advanced phase, where non-terrestrial networks will be a new key feature in the upcoming releases. Narrowband Internet of Things (NB-IoT) is one of the technologies that will address the massive machine type communication (mMTC) traffic of the 5G. To meet the demanding need for global connectivity, satellite communications can provide an essential support to complement and extend the NB-IoT terrestrial infrastructure. However, the presence of the satellite channel comes up with new demands for the NB-IoT procedures. In this paper, we investigate the main challenges introduced by the satellite channel in the NB-IoT random access procedure, while pointing out valuable solutions and research directions to overcome those challenges.