NBIoT Random Access Procedure: System Simulation and Performance

Abstract

The 3rd Generation Partnership Project (3GPP) has defined the Narrow-Band Internet of Things (NBIoT) standard in Long Term Evolution release 13. This paper presents a model of the NB-IoT random-access procedure (RAP) and analyzes and compares its performance allowing decision-making from a system point of view. It includes a fully configurable signal propagation model, and quantifies the number of users camped on a cell and cell and RAP configuration parameters. The paper shows a novel framework to evaluate the RAP proposed in NB-IoT Re1–13 standard with a comprehensive and realistic approach. The contention-based random access is treated considering Msg3 collisions of the RAP instead of the Msgl collisions, where Msgl collisions are treated as a multi-path transmission. This framework includes the machine traffic generation models defined by the 3GPP, the radio transmission effect on the probability of access success, and the random-access (RA) itself. From the foregoing, single-tone and multi-tone transmission performance results have been obtained to show the impact of some parameters that are not typically considered such as the Msg3 transmission mode, Msg3 modulation and coding scheme (MCS), the use of power control mechanisms, and the power ramping step. The results provide interesting information about how these configuration parameters impact on the RAP global performance and insight into its evolution in future systems.