Access Control and Collision Resolution for Massive Random Access in Satellite Internet of Things Networks

Satellite Internet of Things (IoT) networks are characterized by the wide coverage. However, a large number of access requests within the same beam may lead to conflicts and collisions among preamble sequences, hindering the performance and effectiveness of the access of machine-type devices (MTDs). Additionally, different from 5G networks, the satellite-terrestrial networks are accompanied by longer transmission delays, which present challenges for time-sensitive services. To solve the problem of collision fallback resulting from overload during massive random access, a dynamic distributed queue-based random access (DDQRA) approach is proposed to control the overload of satellite IoT networks. The proposed DDQRA can reduce the access delay by adopting the two-step random access approach compared to the traditional four-step random access approach. Moreover, the access class barring (ACB) scheme and the preamble collision resolution algorithm are adopted to control the random access overload and the access priority of different terminal services and resolve the conflict of overload respectively. The simulation results demonstrate that the proposed approach significantly enhances the overall success rate of random access, thereby satisfying the access requirements of time-sensitive MTDs.