Satellite-Based Non-Terrestrial Networks in 5G: Insights and Challenges

Non-terrestrial networks (NTNs) will become an indispensable part of future wirelessnetworks. Integration with terrestrial networks will provide new opportunities for both satellite andterrestrial telecommunication industries and therefore there is a need to harmonize them in a unifiedtechnological framework. Among different NTNs, low earth orbit (LEO) satellites have gained increasingattention in recent years and several companies have filed federal communication commission (FCC)proposals to deploy their LEO constellation in space. This is mainly due to several desired features suchas large capacity and low latency. In addition, recent successful LEO network deployments such as Starlinkhave motivated other companies. In the past satellite and terrestrial wireless networks have been evolvingseparately but now they are joining forces to enhance coverage and connectivity experience in the futurewireless networks. The 3rd Generation Partnership Project (3GPP) is one of the dominating standardizationbodies that is working on various technical aspects to provide ubiquitous access to the 5G networks withthe aid of NTNs. Initial steps have been taken to adopt 5G state of the art technologies and concepts andharmonized them with the conditions met in non-terrestrial networks. In this article, we review some ofthe important technical considerations in 5G NTNs with emphasis on the radio access network (RAN) partand provide some simulation based results to assess the required modifications and shed light on the designconsideration