Performance Evaluation of NR-Based Random Access in LEO Mega-Constellations

This paper investigates the random access capacity in low-earth-orbit mega-constellation. We establish a novel methodology by considering key components, e.g., preamble collision and detection procedures. Leveraging on the system-level simulation platform, we study the impact of latitudes, user density, and random access channel resources on the random access capability. Simulation results reveal that the number of successfully connected users saturates with the growth of user density, and the sat-uration point is around 260 users per second. Furthermore, satellite-centric and user-centric coverage approaches are discussed, and the latter is preferable in terms of the signal-to-interference-plus-noise ratio. In addition, we propose the non-uniform broadcast beam sweeping scheme, and the total access capacity gain of 33.31% is achieved compared to the uniform baseline.