NB-IoT random access procedure via NTN: system level performances

Abstract

With the evolution process of the 5G into the 6G, there will be an exponential growth of the Internet of Things (IoT) devices, offering ubiquitous and continuous connectivity services in all areas of our life. In order to deal with such huge amount of IoT devices, and to satisfy the large capacity requirements of the most advanced of them, non-terrestrial networks (NTNs) will play a pivotal role to assist and complement the terrestrial systems. However, one of the major challenges of the NTN channel is represented by the large delay which hampers the different communication phases, such as the Random Access (RA) procedure. In this paper, we provide an assessment of the system level performances, in terms of access delay and access success probability, of the Narrowband IoT (NB-IoT) devices in typical satellite scenarios defined by the 3GPP. In particular, we provide a detailed analysis under different network densities, for various combinations of the related configuration parameters, and for different system architectures supporting the NB-IoT over NTN. The analysis led to a useful comparison of the RA performances obtained with 3GPP compliant configurations for access parameters and satellite configuration with the aim to maximize the access success probability and minimize the access time in a NB-IoT NTN system.