NR NTN Architecture and Network Protocols

The journey of non-terrestrial networks (NTN) toward the 3rd Generation Partnership Project (3GPP) started years ago in Rel-15 with the first study on scenarios and channel models, followed by another study on architecture in Rel-16. These two studies paved the way for the introduction of NTN in 3GPP specifications in Rel-17. Rel-17 is then the first 3GPP release that supports NTN. In the same release, NTN support for Enhanced Universal Terrestrial RAN Internet of Things and Long Term Evolution Long Term Evolution cat M is also added following a quick study, taking as baseline the same NTN architecture and signaling introduced in New Radio (NR). This chapter presents the NR NTN architecture, focusing on what is specified in Rel-17 but also mentioning other options considered during past studies (especially, regenerative architectures).