Uplink Sum Throughput Analysis and Maximization for Integrated Satellite-Terrestrial Cell-Free Massive MIMO

This paper studies multiple-access scenarios where users are cooperatively served by the satellite and terrestrial access points (APs). We derive the uplink ergodic throughput of scheduled users under practical conditions where maximum-radio combining is exploited locally at the ground gateway and the APs. The analytical result explicitly unveils the effects of pilot contamination and channel conditions on the achievable throughput of each scheduled user in the uplink data transmission. The system can explicitly define the scheduled users and perform the power allocation by maximizing the sum throughput using either model-based or learning-based approaches. Numerical results demonstrate that the cooperation between space and ground systems brings superior throughput improvements over either space or ground networks. Even though most users can be simultaneously served, some may not be scheduled in each coherence interval due to limited radio resources.