Modes and models for satellite integration in 5G networks

5G communication models, based on service-based architectures, network function virtualization, and separation between data and control planes move the attention to network capabilities and functions rather than physical resources. Consequently, 5G-based services can easily rely on satellites to optimize performance or broaden their scope, even transparently to end users. The 3GPP efforts reflect this cutting-edge trend by introducing Non-Terrestrial Network support (in particular satellite), since Rel-16. Nevertheless, the definition of the specific role of the satellite is in continuous evolution and scattered in different 3GPP specification documents, so that actual and future satellite involvement is not easily appreciable. Starting from the state-of-the-art of satellite-related 3GPP standardization and taking into account the outputs of some research projects, this article presents a unified view of the possible satellite integration options in 5G networks.