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

Ata Sattarzadeh,Zhiqun Song,Yun Liu,Abdelrahim Mohamed,Ruiliang Song,Rahim Tafazolli,Chuanfeng Niu,Haipeng Zhang,Pei Xiao

doi:10.1109/access.2021.3137560

Ata Sattarzadeh, Zhiqun Song + Show 7 more

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https://doi.org/10.1109/access.2021.3137560

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Non-terrestrial networks (NTNs) will become an indispensable part of future wireless networks. Integration with terrestrial networks will provide new opportunities for both satellite and terrestrial telecommunication industries and therefore there is a need to harmonize them in a unified technological framework. Among different NTNs, low earth orbit (LEO) satellites have gained increasing attention 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 such as large capacity and low latency. In addition, recent successful LEO network deployments such as Starlink have motivated other companies. In the past satellite and terrestrial wireless networks have been evolving separately but now they are joining forces to enhance coverage and connectivity experience in the future wireless networks. The 3rd Generation Partnership Project (3GPP) is one of the dominating standardization bodies that is working on various technical aspects to provide ubiquitous access to the 5G networks with the aid of NTNs. Initial steps have been taken to adopt 5G state of the art technologies and concepts and harmonized them with the conditions met in non-terrestrial networks. In this article, we review some of the important technical considerations in 5G NTNs with emphasis on the radio access network (RAN) part and provide some simulation based results to assess the required modifications and shed light on the design considerations.

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Wireless networks coverage is limited to the access points’ locations and their footprints
III. 5G NON-TERRESTRIAL NETWORKS we review some of the main challenges in deploying 5G using non-terrestrial satellite networks
Non-terrestrial networks will be an indispensable part of the future networks and several use cases for non-terrestrial networks (NTNs) have been envisioned

Summary

INTRODUCTION

Wireless networks coverage is limited to the access points’ locations and their footprints. Apart from lower signal energy loss, deploying a large number of satellites with restricted footprints and focused beams on the ground, like a cellular network, can provide better frequency reuse capabilities which enhances the total network average spectral efficiency. A. SYNCHRONIZATION Delay and doppler are the two main channel impairments that should be addressed in NTNs. The first step for users to access a 5G network is to receive the synchronization signals transmitted from the satellites and synchronize with a gNB. The pre-compensation is performed according to the doppler of a selected point for each beam (i.e. centre of each beam) and can effectively reduce the maximum CFO within acceptable regions [8] This is possible because of the known location of the beams and ephemeris of the satellite at the network side. Maximum TA difference whithin each beam (msec) Number of beams required to cover

Beam Number

CONCLUSION