Modeling the NB-IoT transmission process with intermittent network availability

Abstract

Standardized by 3GPP, Narrowband Internet-of-Thing (NB-IoT) technology operating in licensed bands is nowadays widely deployed and utilized for static deployments of IoT communications services. The recent trend to equip large complex inherently nomadic systems such as trains and ships with advanced sensory capabilities call for mobility support in NB-IoT technology. Such systems entering and leaving the NB-IoT coverage periodically could lead to synchronized behavior of sensor nodes resulting in occasional spikes in the number of sensors simultaneously accessing the NB-IoT random access channel. In this study, we develop a model capturing behavior of nomadic systems roaming between coverage of NB-IoT technology. The metrics of interest are mean message transmission delay as well as the message loss probability. Our numerical results illustrate that these metrics are mainly affected by the duration of the outage interval and fraction of time systems spends in outage conditions. At the same time, the loss and delay performance only insignificantly affected by the number of sensors implying that NB-IoT random access procedure may efficiently handle sporadic loads.