System-Level Simulation Framework for NB-IoT: Key Features and Performance Evaluation

Narrowband Internet of Things (NB-IoT) is a technology specifically designated by the 3 rd Generation Partnership Project (3GPP) to meet the explosive demand for massive machine-type communications (mMTC), and it is evolving to RedCap. Industrial companies have increasingly adopted NB-IoT as the solution for mMTC due to its lightweight design and comprehensive technical specifications released by 3GPP. This article presents a system-level simulation framework for NB-IoT networks to evaluate their performance. The system-level simulator is structured into four parts: Initialization, pregeneration, main simulation loop, and postprocessing. In addition, three essential features are investigated to enhance coverage, support massive connections, and ensure low power consumption. Simulation results demonstrate that the cumulative distribution function curves of the signal-to-interference-and-noise ratio fully comply with industrial standards. Furthermore, the throughput performance explains how NB-IoT networks realize massive connections at the cost of data rate. This work highlights its practical utility and paves the way for developing NB-IoT networks.