NB-IoT over NTN: Evaluating TBS and Elevation Angle Effects on Communication Reliability

Abstract

With the ever increasing size of the IoT market that utilizes 5G-IoT technologies, NB-IoT and LTE Cat-M, the variety of applications and the demand for functionality are increasing. Due to terrestrial constraints, 5G-IoT technologies cannot be applied globally to suit all use cases such as maritime asset tracking. With the introduction of Non Terrestrial Networks to the 5G ecosystem the newly estabilished standard NB-IoT over Sattelite could cover various use cases. This paper aims to explore the influence of the elevation angle of the gNodeB located in LEO (Low-Earth Orbit) related to the end-user device, as well as the TBS (Transport Block Size) configuration quantified by a Block Error Rate (BLER). A simulation in MATLAB 5G Toolbox was performed and the elevation angle with TBS changed in granual steps. The results show that the BLER drops significantly with higher elevation angles as well as increases with increasing orbital height of the gNodeB. The TBS influences the success rate of the communication link where the BLER decreases with smaller TBS configuration.