  We provide an overview of the 3rd generation partnership project (3GPP) work
on evolving the 5G wireless technology to support non-terrestrial satellite
networks. Adapting 5G to support non-terrestrial networks entails a holistic
design spanning across multiple areas from radio access network to services and
system aspects to core and terminals. In this article, we describe the main
topics of non-terrestrial networks, explain in detail the design aspects, and
share various design rationales influencing standardization.
