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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
5G Non-Terrestrial Networks Provides a complete and detailed description of the non-terrestrial component in the 5G ecosystem 5G Non-Terrestrial Networks is the first multi-authored reference dedicated to the integration of non-terrestrial networks (NTN) into the 5G ecosystem. Written by leaders in the development of the 3GPP 5G NTN specification, this authoritative resource addresses all key aspects of non-terrestrial components of 5G systems, including standardization, architecture, protocols, and regulatory considerations. Drawing from their expertise in academic and industrial research and development, the authors introduce fundamental principles of non-terrestrial communications, define the NTN architecture and radio protocol stacks, describe applications to support mobility and radio resource management, and more. The book covers 5G New Radio-based technology for NTN as well as LTE NB-IoT/eMTC, providing a well-rounded understanding of the unique characteristics of 5G-NTN systems. Throughout the text, the authors offer insights on various design approaches, technical choices, and trade-off options. In addition, the book: * Addresses the integration of non-terrestrial networks into 5G systems at all levels * Describes the principles of non-terrestrial systems, including orbital parameters, link budget, propagation, and space/ground segments * Includes a detailed overview of 5G-NTN system architectures, deployment scenarios, and spectrum aspects * Covers NB-IoT and eMTC in NTN, NTN use cases, 5G QoS, and New Radio * Discusses the potential of non-terrestrial components of 5G in the future 6G ecosystem 5G Non-Terrestrial Networks is a must-have for communication engineers, satellite network operators, aerospace and electrical engineers, network engineers, academic researchers and industry professionals involved in 5G infrastructure development, as well as advanced students taking courses on 5G and satellite communication.
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Table of Contents
Cover
Table of Contents
Title Page
Copyright
Dedication
Preface
About the Authors
Acknowledgments
Acronyms
1 Introduction
1.1 What is 5G NTN?
1.2 Use Cases for 5G NTN
1.3 ITU-R Vision and Requirements on the Satellite Component of IMT-2020
1.4 NTN Roadmap in 3GPP
1.5 3GPP Requirements for 5G via Satellite
1.6 Technical Challenges
1.7 Satellite RAN Architecture
1.8 NTN Spectrum
1.9 3GPP Work on NTN in Release-15 and Release-16
1.10 3GPP work on NTN in Release-17 and Release-18
1.11 NTN in Release-19 and Beyond
1.12 3GPP and Standardization
References
Notes
2 The 3GPP 5G Overview
2.1 Introduction
2.2 5G System Architecture
2.3 3GPP and 5G Standardization
References
3 Non-Terrestrial Networks Overview
3.1 Elements of a Satellite Communications System
3.2 Orbits and Constellations
3.3 Propagation and Link Performance
References
Notes
4 NR NTN Architecture and Network Protocols
4.1 Introduction
4.2 Architecture Overview
4.3 User Plane and Control Plane
4.4 Interworking with Terrestrial Mobile Networks
4.5 Impact on Other Technologies: IoT NTN
4.6 Regenerative Architectures
4.7 Conclusions
References
Note
5 NR NTN Radio Interface
5.1 Introduction
5.2 NR Basic Transmission Scheme
5.3 Downlink Synchronization Procedure in NTN
5.4 Uplink Synchronization Procedure in NTN
5.5 NR Timing Relationships Enhancements for NR NTN
5.6 Hybrid ARQ Enhancements for NR NTN
References
Notes
6 Impacts on the System Architecture and Network Protocol Aspects
6.1 Introduction
6.2 5G QoS and NTN
6.3 Network Attach, AMF Selection, and UE Location
6.4 Random-access Procedure
6.5 Other Enhancements at MAC
6.6 RLC, PDCP Enhancements
6.7 NTN-specific System Information
6.8 Mobility Aspects
6.9 Feeder Link Switchover
6.10 Network Management Aspects
Annex
References
Notes
7 RF and RRM Requirements
7.1 Frequency Bands In Which NTN Can Operate
7.2 NTN Architecture and Interfaces
7.3 Definition of RF Performances and Related Methodology
7.4 RRM Requirements
References
8 NB-IoT and eMTC in NTN
8.1 Overview
8.2 Architecture and Deployments Scenarios
8.3 Enhancements for NB-IoT/eMTC Support in NTN
References
Notes
9 Release 18 and Beyond
9.1 NTN in the Evolving Context of 5G, Beyond 5G and 6G
9.2 Non-Terrestrial Networks and 5G
9.3 Toward 6G and Non-Terrestrial Networks
References
Index
End User License Agreement
List of Tables
Chapter 1
Table 1.1 LEO Network specific characteristics creating and related technica...
Table 1.2 NTN operating bands in FR1-NTN.
Table 1.3 NTN operating bands in FR2-NTN (under definition).
Table 1.4 ITU-R frequency ranges above 10 GHz for Satellite Communications....
Table 1.5 List of satellite-related activities in 3GPP in the different TSG ...
Table 1.6 List of satellite-related activities in 3GPP in the different TSG ...
Table 1.7 3GPP RAN specifications updated for the integration of satellite c...
Table 1.8 Release-19 enhancements on system architecture for the support of ...
Table 1.9 Further enhancements/features for NR NTN in Release-19.
Table 1.10 Further enhancements/features for IoT NTN in Release-19
Table 1.11 Relevant 3GPP working groups for Non-Terrestrial Networks.
Chapter 2
Table 2.1 Connectivity options [22]. Option 2 also supports NR as both Maste...
Chapter 3
Table 3.1 Summary of constants of motion for bounded orbits.
Table 3.2 Summary of one-way and RTT delays for GEO and LEO satellites at
60
...
Table 3.3 Doppler characterization for LEO satellites.
Table 3.4 Doppler characterization for GEO satellites.
Table 3.5 Satellite parameters for system-level assessment, Set-1.
Table 3.6 Satellite parameters for system-level assessment, Set-2.
Table 3.7 UE parameters for system-level assessment.
Table 3.8 NTN DL link budget with Set-1 parameters.
Table 3.9 NTN DL link budget with Set-2 parameters.
Table 3.10 NTN UL link budget with Set-1 parameters.
Table 3.11 NTN UL link budget with Set-2 parameters.
Chapter 4
Table 4.1 Bandwidth required for fronthaul transport (DL only), for various ...
Chapter 5
Table 5.1 PAPR for DFT-spread OFDM [10].
Table 5.2 The value of
N
TA
,
offset
.
Table 5.3 Maximum timing advance update per TAC in RAR.
Table 5.4 Maximum timing advance update per TAC in MAC CE.
Table 5.5 Supported Satellite ephemeris parameters in 3GPP Release-17.
Table 5.6 Orbit propagation errors at the UE [16].
Table 5.7 Common TA parameters definition.
Table 5.8 Epoch time and validity duration parameters.
Table 5.9 Max Doppler shift/drift to be supported in NTN scenarios [2].
Table 5.10 Definition of cell-specific Koffset.
Table 5.11 Definition of kmac.
Table 5.12 Fields related to HARQ in DCI formats for scheduling of PDSCH.
Table 5.13 Fields related to HARQ in DCI formats for scheduling of PUSCH.
Table 5.14 Number of HARQ processes in NTN.
Table 5.15 Enhancement on the HARQ process indication.
Chapter 6
Table 6.1 SIB19 content.
Table 6.2 Measurement events.
Table 6.A.1 Standardized mapping of 5QI to QoS characteristics.
Chapter 7
Table 7.1 Possible satellite service allocated frequency bands for NTN.
Table 7.2 NTN operating bands in FR1 for satellite networks.
Table 7.3 NTN operating bands above 10 GHz for satellite networks.
Table 7.4 Possible frequency bands for HAPS networks.
Table 7.5 NTN operating bands in FR1 for HAPS networks.
Table 7.6 ACLR/ACS values for TN BS and TN UE (2 GHz).
Table 7.7 ACLR/ACS for TN (2 GHz).
Table 7.8 Selected scenario for each interference type.
Table 7.9 SAN channel bandwidths and SCS per operating band in FR1.
Table 7.10 SAN Classes in Release-17.
Table 7.11 ACLR and ACS of 5G NR NTN SAN and NTN UE in Release-17.
Table 7.12
T
e_NTN
timing error limit.
Table 7.13
T
q_NTN
maximum autonomous time adjustment step and
T
p_NTN
minimum...
Chapter 8
Table 8.1 UE maximum output power in NTN.
Table 8.2 NB-IoT/eMTC reference scenarios from TR 36.763.
Table 8.3 Set-1 of satellite parameters for NB-IoT/eMTC.
Table 8.4 Set-2 of satellite parameters for NB-IoT/eMTC.
Table 8.5 Set-3 of satellite parameters for NB-IoT/eMTC [5].
Table 8.6 Set-4 of satellite parameters for NB-IoT/eMTC [5].
Table 8.7 Set-5 of satellite parameters for NB-IoT/eMTC [5].
Table 8.8 UTRA satellite access operating bands.
Table 8.9 Channel bandwidth.
Table 8.10 SIB31(-NB) parameters for timing and frequency pre-compensation....
Table 8.11 SIB31(-NB) parameters for timing relationship enhancements.
Table 8.12 SIB32 content.
List of Illustrations
Chapter 1
Figure 1.1 Percentage of launched satellites per service type between 1974 a...
Figure 1.2 Number of launched satellites per orbit.
Figure 1.3 From SatCom to NTN.
Figure 1.4 Toward a network unifying NTN–TN network components.
Figure 1.5 3GPP Works on NTN up to Rel-18.
Figure 1.6 3GPP defined satellite network solutions for 5G.
Figure 1.7 Integration of non-terrestrial and terrestrial networks for both ...
Figure 1.8 Satellite component of IMT-2020 usage scenarios.
Figure 1.9 Requirements for the satellite radio interface(s) of IMT-2020....
Figure 1.10 Satellite-related study and work items in 3GPP.
Figure 1.11 NTN based RAN architecture with transparent satellite.(a) NT...
Figure 1.12 3GPP Rel-17 NTN impacts on 3GPP specifications.
Figure 1.13 3GPP and standardization.
Figure 1.14 Estimated number of Technical Documents submitted to the 3GPP TS...
Chapter 2
Figure 2.1 The NG-RAN logical architecture [6].
Figure 2.2 NG-RAN architecture with a split gNB [5].
Figure 2.3 NG-RAN architecture with separation of gNB-CU-CP and gNB-CU-UP [5...
Figure 2.4 3GPP structure.
Chapter 3
Figure 3.1 Segments and links of a general Non-Terrestrial Network (NTN) sys...
Figure 3.2 Orbit shape as a function of the eccentricity.
Figure 3.3 Satellite velocity and period in a circular orbit as a function o...
Figure 3.4 Definition of the Keplerian orbital elements.
Figure 3.5 Main orbits for artificial satellites around the Earth.
Figure 3.6 Instantaneous and long-term system coverage.
Figure 3.7 Walker Star (a) and Delta (b) constellations.
Figure 3.8 System architecture and orbit determination steps [9].
Figure 3.9 Reference diagram for the Earth–satellite geometry.
Figure 3.10 Slant range as a function of the elevation angle for different s...
Figure 3.11 Example of FoV for a GEO satellite, SSP at Lat = 0° , Lon...
Figure 3.12 Example of FoV for a LEO satellite at 200 km (a) and 1000 km (b)...
Figure 3.13 Minimum and maximum one-way propagation delay for transparent an...
Figure 3.14 GEO satellite orbital box (a) and trajectory with perturbations ...
Figure 3.15 Link configuration.
Chapter 4
Figure 4.1 NTN in 3GPP Rel-17.
Figure 4.2 Dual connectivity with Rel-17 NTN architecture [2].
Figure 4.3 NTN based on a transparent satellite, showing end-to-end mapping ...
Figure 4.4 Control plane stack for NTN [2].
Figure 4.5 User plane stack for NTN [2].
Figure 4.6 Dual connectivity involving NTN and terrestrial networks [2].
Figure 4.7 NTN for E-UTRAN IoT/MTC in 3GPP Rel-17.
Figure 4.8 Regenerative satellite with ISL [2].
Figure 4.9 NG-RAN with a regenerative satellite based on gNB-DU [2].
Figure 4.10 Possible split between a “central” and a “distributed” unit with...
Figure 4.11 Possible lower layer split options studied in 3GPP. DL is on the...
Chapter 5
Figure 5.1 NR Resource Block (RB).
Figure 5.2 NR Frame structure.
Figure 5.3 NR Downlink channels.
Figure 5.4 NR Uplink channels.
Figure 5.5 Polarization reuse scheme used together with frequency reuse.
Figure 5.6 DL frequency compensation for Doppler in Release-17.
Figure 5.7 Uplink/Downlink radio frame timing in TN.
Figure 5.8 Uplink/Downlink radio frame timing at the gNB and the UE in NTN....
Figure 5.9 UE-specific TA and Common TA.
Figure 5.10 NTN Higher-layer parameters handling.
Figure 5.11 Epoch time explicitly provided in
ntn-Config
-r17 for serving cel...
Figure 5.12 Epoch time explicitly provided in
ntn-Config
-r17 for neighbor ce...
Figure 5.13 Uplink synchronization validity duration and associated UE behav...
Figure 5.14 Time when UL synchronization is obtained after SIB19 is acquired...
Figure 5.15 Timing Advance adjustment in NR NTN.
Figure 5.16 An example to justify the necessity of introducing an additional...
Figure 5.17 Differential Koffset MAC Control Element.
Figure 5.18 Random access procedure.
Figure 5.19 Fallback for RA with 2-step RA type.
Figure 5.20 Msg2 (RAR) window and ra-ContentionResolution delayed by UE-gNB ...
Figure 5.21 Transmission timing of PUSCH in TN.
Figure 5.22 Transmission timing of DCI scheduled PUSCH in NTN using Koffset ...
Figure 5.23 MAC PDU structure.
Figure 5.24 MAC CE timing relationships in TN.
Figure 5.25 MAC CE timing relationships in NTN when DL and UL frame timing a...
Figure 5.26 MAC CE timing relationship enhancement with
K
mac
.
Figure 5.27 The timing relationship for beam failure recovery enhanced with
Figure 5.28 Hybrid ARQ principles in NR.
Figure 5.29 HARQ stalling.
Figure 5.30 Example of enhanced semi-static (Type-1) HARQ-ACK codebook.
Figure 5.31 Example of enhanced semi-static (Type-1) HARQ-ACK codebook and C...
Figure 5.32 Example of enhanced dynamic (Type-2) HARQ-ACK codebook.
Figure 5.33 Transmission timing for HARQ-ACK on PUCCH in terrestrial network...
Figure 5.34 Transmission timing for HARQ-ACK on PUCCH in NTN.
Chapter 6
Figure 6.1 Classification and UP marking for QoS flows, and mapping to AN re...
Figure 6.2 Random Access Procedure.
Figure 6.3 The random-access procedure when UE operates in NTN.
Figure 6.4 HARQ procedure in NTN.
Figure 6.5 Example of logical channel prioritization (LCP) operation.
Figure 6.6 Timer for scheduling request transmission.
Figure 6.7 Measurement rules for cell reselection.
Figure 6.8 Received signal strength in (a) Terrestrial Network, (b) NTN.
Figure 6.9 Entering condition of Event D1.
Figure 6.10 “Hard” feeder link switchover for non-geostationary satellites....
Figure 6.11 “Soft” feeder link switchover for non-geostationary satellites....
Figure 6.12 NTN-based NG-RAN [4].
Chapter 7
Figure 7.1 ITU regions and the dividing lines between them: Region 1 (Europe...
Figure 7.2 5G NR satellite system architecture in Release-17.
Figure 7.3 S-band NTN-TN adjacent band coexistence scenarios with TN in FDD ...
Figure 7.4 S-band NTN-TN adjacent band coexistence scenarios with TN in TDD ...
Figure 7.5 Throughput Loss (%) as a function of ACIR (dB) for TN-NTN coexist...
Figure 7.6 System architecture overview.
Chapter 8
Figure 8.1 Cellular IoT in 3GPP Roadmap.
Figure 8.2 IoT NTN EUTRAN architecture.
Figure 8.3 UE-specific TA and Common TA.
Figure 8.4 Frequency pre-compensation in IoT-NTN.
Figure 8.5 Short, sporadic transmissions for IoT over NTN.
Figure 8.6 Long connection with connected mode DRX for IoT over NTN.
Figure 8.7 Discontinuous coverage in NTN IoT.
Figure 8.8 Tracking Area handling in Cellular IoT over satellite access.
Chapter 9
Figure 9.1 Interactions between “terrestrial” and non-terrestrial networks b...
Figure 9.2 Rel-17 NTN impacts on 5G NR/NG-RAN specifications.
Figure 9.3 Reference scenarios for 5G NTN.
Figure 9.4 Enhanced capabilities compared to 5G.
Figure 9.5 New capabilities enabled by 6G.
Figure 9.6 Key design principles of non-terrestrial networks for B5G/6G.
Figure 9.7 3GPP standardization schedule with respect to IMT-2030 definition...
Guide
Cover
Table of Contents
Title Page
Copyright
Dedication
Preface
About the Authors
Acknowledgments
Acronyms
Begin Reading
Index
End User License Agreement
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IEEE Press445 Hoes LanePiscataway, NJ 08854
IEEE Press Editorial BoardSarah Spurgeon, Editor in Chief
Jón Atli Benediktsson Anjan Bose James Duncan Amin Moeness Desineni Subbaram Naidu
Behzad Razavi Jim Lyke Hai Li Brian Johnson
Jeffrey Reed Diomidis Spinellis Adam Drobot Tom Robertazzi Ahmet Murat Tekalp
5G Non-Terrestrial Networks
Technologies, Standards, and System Design
Alessandro Vanelli-Coralli
University of BolognaItaly
Nicolas Chuberre
Thales Alenia Space – FranceFrance
Gino Masini
Ericsson ABSweden
Alessandro Guidotti
CNIT, Research Unit at the University of BolognaItaly
Mohamed El Jaafari
Thales Alenia Space – FranceFrance
Copyright © 2024 by The Institute of Electrical and Electronics Engineers, Inc.All rights reserved.
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Library of Congress Cataloging-in-Publication Data:
Names: Vanelli-Coralli, Alessandro, author.
Title: 5G non-terrestrial networks / Alessandro Vanelli-Coralli [and four others].
Description: Hoboken, New Jersey : Wiley, [2024] | Includes index.
Identifiers: LCCN 2023048993 (print) | LCCN 2023048994 (ebook) | ISBN 9781119891154 (hardback) | ISBN 9781119891161 (adobe pdf) | ISBN 9781119891178 (epub)
Subjects: LCSH: 5G mobile communication systems. | Artificial satellites.
Classification: LCC TK5103.25 .V36 2024 (print) | LCC TK5103.25 (ebook) | DDC 621.3845/6–dc23/eng/20231122
LC record available at https://lccn.loc.gov/2023048993
LC ebook record available at https://lccn.loc.gov/2023048994
Cover Design: WileyCover Image: © metamorworks/Shutterstock
To our families, Elena, Leonardo, Caterina, Daniela, Luigi, Lucia, Giulia, Nabiha, Rassane, Maryam, Anne-Claire, Marine, Alix, Cyprien, Xavier, and Hélène, for their continuous support and encouragement.
Preface
For many years, the cellular industry has had the goal to provide its services anytime, anywhere, and on any device (ATAWAD). Such a goal was always postponed to the next generation of mobile systems. What became a dream will now be reality with 3rd Generation Partnership Project (3GPP) Release-17 technical specifications allowing the addition of non-terrestrial network (NTN) components in the 5G system. Leveraging this global standard, industrial initiatives aim at developing and deploying new satellite networks that are able to directly serve smartphones and IoT devices. Moreover, this standard will contribute to create a global market for broadband satellite networks operating in above 10 GHz frequency bands facilitating their interworking with terrestrial communication infrastructure for the support of backhaul services, as well as connectivity to any moving platforms (aircraft, vessels, trains, and land vehicles).
This book aims at providing an overview of this 3GPP-defined “NTN” standard. Aimed at easing the inclusion of NTN elements in the 5G ecosystem, the work was conducted within the 3GPP starting with the identification of the technical challenges and potential solutions to support New Radio (NR) protocols and features over satellite links. This marked a radical paradigm shift in how mobile communication standards are defined, as now we are moving to satellite-terrestrial integration. The first global standard for an NTN component in the 5G system was published mid-2022 in the context of 3GPP Release-17. This standard provides the specifications for 5G systems to support a satellite component. However, it should be mentioned that it does not just represent a set of technical specifications, but it rather opens the door for the satellite industry to enter the 3GPP ecosystem, which involved more than 800 organizations at global level working to ensure a global market for telecommunications.
The 3GPP-defined NTN standard is the result of a massive joint effort between stakeholders from both the terrestrial and satellite industries, which leads to a two-fold benefit. On the one hand, 3GPP can now truly achieve global service continuity and network resiliency; on the other hand, satellite stakeholders can now access the unified and global 3GPP ecosystem and, as such, the possibility to reduce the costs through economy of scale. Moreover, the inclusion of a non-terrestrial component in 3GPP can also yield huge benefits for the satellite industry as ground systems exploiting equipment coming from different providers are now available. Notably, this standard is also supported by vertical stakeholders (including public safety, transportation, and automotive) calling for the seamless integration of satellite and terrestrial components and the support of 5G features across these different radio access technologies.
The addition of the NTN component in 5G systems is already creating a global market for satellite communication industry stakeholders and a unique technology framework for satellite networks based on whatever orbit, frequency band, and service provision considering a variety of terminal types (including smartphones and very small aperture terminals), as well as an open architecture approach.
While the current Release-17 NTN standard provides a solid ground for future satellite networks integrated into the 5G system, a significant innovation breakthrough in technologies, techniques, and architectures is needed to prepare for next-generation satellite networks based on Release-19 and beyond, which will pave the way for 6G communications. At the time of writing this book, 3GPP Release-18 is being defined and it includes enhancing features to further improve the performance or to introduce new capabilities for the support of NTN. Moreover, the discussions on the potential topics to be addressed in the 3GPP Release-19 package are already ongoing.
In this context, this book aims to provide a complete and comprehensive overview of the study and normative activities that led to the definition of the first NTN component in the 3GPP 5G ecosystem within Release-17 and to provide a guideline for the ongoing normative work in 3GPP Release-18. More specifically, the following topics are addressed:
Chapter 1
provides an introduction to satellite communications and NTNs and what their role is in 5G systems. The evolution of 3GPP specifications throughout the study phase (Release-15 and -16) and the normative phase (Release-17 and beyond) is discussed.
Chapter 2
introduces the 3GPP ecosystem and the global 5G standard, in terms of architectures (core and radio access), enabling features, and interfaces and protocols. This chapter introduces the reader to 5G systems and 3GPP procedures.
Chapter 3
provides an overview of NTNs, addressing the network elements (ground, space, and user segment), orbits and orbital propagation aspects, Earth-satellite geometry, and link budget computation. The scope of this chapter allows readers who are not experts in satellite communications to enter the 3GPP NTN world and understand its underlying principles.
Chapter 4
is dedicated to NR NTN architectures and network protocols, interfaces, and functionalities for both the
user
and
control
planes; these discussions are not limited to Release-17, which is built assuming transparent payloads, but also covers the more advanced options with regenerative payloads that are expected for 5G-Advanced. Aspects related to the interworking with terrestrial network components are also covered.
Chapter 5
reports an extensive description of the NTN radio interface at physical layer, covering the basic transmission principles (waveform, modulation and coding, multiple access scheme, framing, operating frequency, and radio channels), more advanced topics, and the necessary physical layer mechanisms and procedure modifications for the 5G NR to support a satellite-based access.
Chapter 6
provides an extensive review of the impacts on the system architectures and network protocols that the introduction of the NTN characteristics has. In particular, the discussion addresses the handling of
quality of service
(
QoS
), attachment procedures for the
user equipment
(
UE
), mobility, feeder link switch, and network management. As for the previous chapter, the focus is on Release-17, but also the ongoing enhancements for Release-18 are presented.
Chapter 7
addresses
radio frequency
(
RF
) and
radio resource management
(
RRM
) aspects, in terms of requirements and target performance, also taking into account the recommendations set forth by the
International Telecommunication Union Radiocommunication
sector (
ITU-R
).
Chapter 8
provides an overview of
narrowband Internet-of-Things
(
NB-IoT
) and
enhanced Machine Type Communications
(
eMTC
) via NTN, covering 3GPP normative activities and the impact of the NTN channel on radio protocols and the related enhancements.
Chapter 9
covers the further enhancements and capabilities of NTNs in the evolving context of 5G-Advanced as well as 6G, including both standardization aspects and industrial perspectives. An overview of the preliminary expectations related to NTN in 6G systems is detailed.
December 22, 2023
Alessandro Vanelli-CoralliUniversity of BolognaNicolas ChuberreThales Alenia SpaceGino MasiniErcisson ABAlessandro GuidottiCNIT Research Unit at the University of BolognaMohamed El JaafariThales Alenia Space
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About the Authors
Alessandro Vanelli-Coralli, PhD, is a full professor of telecommunications at the Department of Electrical, Electronic, and Information Engineering “Guglielmo Marconi,” University of Bologna, Italy. Since March 2022, he has been a research fellow in the Digital Integrated Circuits and Systems group at ETH Zurich (CH) working on RISC-V-based multicore platforms for 5G and 6G signal processing. From January to June 2021, he was a visiting professor at ETH Zurich working on Internet of Things (IoT) software-defined radio. In 2003 and 2005, he was a visiting scientist at Qualcomm Inc. (San Diego, CA). His research activity focuses on wireless communication with specific emphasis on 5G and 6G systems and non-terrestrial networks (NTNs). His pioneering work on heterogeneous satellite networks in 2009 set the basis for the concept of 3D multidimensional NTNs (A. Vanelli-Coralli et al. “The ISICOM Architecture,” 2009 International Workshop on Satellite and Space Communications). He participates in national and international research projects on satellite mobile communication systems serving as scientific responsible and prime contractor for several European Space Agency (ESA) and European Commission funded projects. He participates in industrial and scientific fora and bodies, he is responsible for the vision and research strategy task force of the NetworldEurope SatCom Working Group, and he is the delegate for the University of Bologna in the 6G-IA, ETSI, and 3GPP. He served as a member of the editorial board of the Wiley InterScience Journal on Satellite Communications and Networks, as guest co-editor for several special issues in international scientific journals, and since 2010 he has been the general co-chairman of the IEEE ASMS Conference. He co-authored more than 290 peer-reviewed papers and he is co-recipient of several best paper awards. He is an IEEE senior member and the 2019 recipient of the IEEE Satellite Communications Technical Recognition Award.
Nicolas Chuberre graduated in 1988 from Ecole Supérieure d'Ingénieur en Electronique et Electrotechnique in Paris. Previously with Nokia and Alcatel Mobile to design signal processing algorithms, medium access control protocols, and test tools for 2G cellular handsets and systems assembly, he then joined Thales Alenia Space to manage the development of satellite payload equipment and the design of advanced satellite communication systems (GEO and non-GEO). He has successfully initiated and led several European collaborative research projects in FP6, FP7, and H2020, as well as the ESA ARTES context. He has been chairing the SatCom Working Group of Networld2020 technology platforms (https://www.networld2020.eu/) for nine years and was a member of the partnership board of the 5G Infrastructure Association (http://5g-ppp.eu/). He has published several papers on innovative satellite system concepts. Currently, he is defining and developing satellite solutions for 5G and 6G systems. In addition, he is the lead representative of Thales in 3GPP TSG RAN where he has been the rapporteur of the standardization on the integration of satellite in 5G since 2017 (https://www.3gpp.org/news-events/partners-news/2254-ntn_rel17). He also chairs since 2006 the satellite communication and navigation working group at ETSI (www.etsi.org). Last, he is the technical manager of the Horizon Europe research project “6G-NTN” (https://www.6g-ntn.eu/).
Gino Masini is principal researcher with Ericsson in Sweden. In his many years in telecommunications in both industry and academia, he has worked with microwave antennas and propagation, satellite telecommunications, microwave circuit research and development, backhaul network design, and radio access network architecture. He received his electronics engineering degree from Politecnico di Milano in 1996 and an MBA from SDA Bocconi School of Management in Milano in 2008. He started as a researcher at Politecnico di Milano, working on projects for the ESA and the Italian Space Agency (ASI); through that activity, he contributed to the background for millimeter wave propagation experiments such as the Alphasat satellite mission. He later joined Ericsson, working with antennas and planning for microwave radio links and with MMIC development. Since 2009 he has been working with 4G and 5G radio access network architecture. He has been working in standards since 2001, having attended 3GPP, ETSI, ITU, and CEPT, among others. He has been active in 3GPP since 2009, he was RAN WG3 chairman from 2017 to 2021, overseeing the standardization of 5G radio network architecture, interfaces, and protocols. He is the author of more than 70 patents and several scientific publications, and he is co-author of books on 5G radio access networks; he also holds a “Six Sigma” certification.
Alessandro Guidotti received the Dr. Ing. degree (magna cum laude) in telecommunications engineering and the PhD in electronics, computer science, and telecommunications from the University of Bologna (Italy) in 2008 and 2012, respectively. In 2012 he joined the Department of Electrical, Electronic, and Information Engineering (DEI) at the University of Bologna. During his PhD from 2008 to 2012, he was the representative for the Italian Administration within the CEPT SE-43 working group on cognitive radios. In 2011–2012, he spent some months as a visiting researcher at SUPELEC (Paris, France) working on the application of stochastic geometry to interference characterization in wireless networks. From 2012 to 2014 and from 2014 to 2021, he was a post-doctoral researcher and research associate at the University of Bologna, respectively. Since 2021, he has been a senior researcher within the National Inter-University Consortium for Telecommunications (CNIT), working at the research unit of the University of Bologna. He participates in national and international research projects on satellite and terrestrial mobile communication systems. His research interests are in the area of wireless communication systems, NTNs, satellite-terrestrial networks, and digital transmission techniques. He is a member of the IEEE AESS Technical Panel on Glue Technologies for Space Systems, and since 2016 he is TPC and Publication Co-Chair of the IEEE ASMS/SPSC Conference.
Mohamed El Jaafari is a radio access network specialist engineer with more than 23 years of experience in cellular communications, including 5G NR, eUTRAN, GERAN, and cellular IoT. He received an engineering degree in telecommunications from EMI in 1999. He is an expert in radio access network design, radio frequency planning, radio network optimization, and radio access network system dimensioning with extensive multi-vendor experience. He currently conducts extensive research work on 5G NR NTN and IoT NTN. He joined the R&D department of the Telecommunication Business Line of Thales Alenia Space in 2020. He is the lead representative of Thales in 3GPP RAN1 working group where he is a feature lead for the 3GPP work item on satellite integration in 5G. Currently, he is defining and developing solutions for 5G NR to support NTNs. He is active in national and international research projects on wireless and satellite communication systems in several ESA and European Commission funded projects. His research interests include 3GPP wireless communication systems, satellite communications, and their integration in 5G and future 6G networks. He has recently led the drafting of a special edition on NTN standards, https://onlinelibrary.wiley.com/toc/15420981/2023/41/3.
Acknowledgments
The authors would like to express their special gratitude to Mr. Dorin Panaitopol from Thales, for the valuable inputs related to radio frequency (RF) and radio resource management (RRM) aspects and his careful review of the corresponding chapter, and to Dr. Carla Amatetti from the University of Bologna, Italy, for the discussions and contributions on narrowband Internet of Things (NB-IoT) via non-terrestrial network (NTN).
This NTN standardization adventure has involved numerous 3rd Generation Partnership Project (3GPP) experts from the global telecom industry. It is fair to praise the work of 3GPP leadership that had the difficult task of moderating the discussions between two different ecosystems (satellite and mobile industry) in the different groups of 3GPP with an attempt to build consensus on the various aspects of the NTN standard.
TSG-SA chair: Erik Guttman (Samsung) then Georg Mayer (Huawei) then Puneet Jain (Intel)
SA1 WG chair: Toon Norp (TNO) then Jose Almodovar (TNO)
SA2 WG chair: Frank Mademann (Huawei) then Puneet Jain (Intel)
SA3 WG chair: Suresh Nair (Nokia)
SA3-LI WG chair: Alex Leadbeater (BT group)
SA5 WG chair: Thomas Tovinger (Ericsson)
TSG-RAN chair: Balazs Bertenyi (Nokia) then Wanshi Chen (Qualcomm)
RAN1 WG chair: Wanshi Chen (Qualcomm) then Younsun Kim (Samsung)
RAN1 WG vice chair: Havish Koorapaty (Ericsson) then David Mazzarese (Huawei)
RAN2 WG chair: Richard Burbridge (Intel) then Johan Johansson (Mediatek)
RAN2 WG vice chairs: Diana Pani (Inter Digital) and Sergio Parolari (ZTE)
RAN3 WG chair: Gao Yin (ZTE) who took over from Gino Masini (Ericsson)
RAN4 WG Chair: Steven Chen (Futurewei) then Xizeng Dai (Huawei)
RAN4 WG vice chairs: Haijie Qiu (Samsung) on RF aspects and Andrey Chervyakov (Intel) on RRM aspects
Special thanks to the many experts involved very early in the NTN standardization work among which are: Tommi Jamsa (Huawei), Frank Hsieh (Nokia), Gilles Charbit (Mediatek), Nan Zhang (ZTE), Xiaofeng Wang (Qualcomm), Philippe Reininger (Huawei), Martin Israelsson (Ericsson), Stefano Cioni (ESA), Munira Jaffar (Hughes), Olof Liberg (Ericsson), Thibaud Deleu (Thales), Baptiste Chamaillard (Thales), Thomas Heyn (Fraunhofer IIS), Thomas Haustein (Fraunhofer HHI), Mohamed El Jaafari (Thales), Cyril Michel (Thales), Relja Djapic (TNO), Saso Stojanovski (Intel), Hannu Hietalahti (Nokia), Matthew Baker (Nokia), Thomas Chapman (Ericsson), Luca Lodigiani (Inmarsat), and Jean-Yves Fine (Thales).
The support of ETSI MCC secretaries such as Joern Krause, Patrick Merias, and Maurice Pope in the various 3GPP groups shall also be underlined.
Current industry activities on 5G via satellite would not have been possible without
the support of:
the European Space Agency (especially Antonio Franchi, Xavier Lobao, Maria Guta, and Dr. Riccardo di Gaudenzi)
the European Commission (especially Mr. Bernard Barani)
the European Telecommunication Standard Institute (especially Mr. Adrian Scrase)
space industry's leaders (Bertrand Maureau/Thales, Didier Le Boulc'h/Thales, Stéphane Anjuere/Thales, Lin-Nan Lee/Hughes Network System)
And the groundbreaking work by a number of pioneers in our field. Among them:
Prof. Francesco Carassa (Politecnico di Milano): Our fond thoughts go to his memory. In 1977 his Sirio satellite enabled for the first time the investigation of the 12–18 GHz frequencies for satellite communications.
Prof. Barry Evans (University of Surrey) and Prof. Giovanni E. Corazza (University of Bologna) who both led numerous research activities on the integration of satellites with mobile communications.
Dr. Walter Zoccarato and Mr. Mathieu Arnaud (Thales) who demonstrated the technical feasibility of direct satellite-to-smartphone connectivity. Mr. Romain Bucelle (Thales) who identified the enablers for an economically viable “Direct to Device” system.
Mr. Laurent Combelles (Thales) and Mr. Sebastian Euler (Ericsson) for their exceptional work at ITU-R paving the way for the recognition of NTN as an IMT2020 satellite radio interface.
Acronyms
3D
Three-dimensional
3GPP
3rd Generation Partnership Project
5G
Fifth Generation
5GC
5G Core Network
5QI
5G QoS Identifier
ACK
Acknowledgment
ACLR
Adjacent Channel Leakage Ratio
ACS
Adjacent Channel Selectivity
AI
Artificial Intelligence
AM
Acknowledged Mode
AMF
Access and Mobility Management Function
AN
Access Network
AoI
Area of Interest
AR
Augmented Reality
ARP
Allocation and Retention Priority
ARQ
Automatic Repeat Request
AS
Access Stratum
BAP
Backhaul Adaptation Protocol
BCCH
Broadcast Control Channel
BCH
Broadcast Channel
BPSK
Binary Phase-Shift Keying
BWP
Bandwidth Part
CAG
Closed Access Group
CBG
Code Block Group
CBGFI
Code Block Group Flush Indicator
CBGTI
Code Block Group Transmission Information
CC
Component Carrier
CCCH
Common Control Channel
cDAI
counter Downlink Assignment Index
CE
Control Element
CFO
Carrier Frequency Offset
CHO
Conditional Handover
CM
Cubic Metric
cMTC
Critical MTC
CNR
Carrier-to-Noise Ratio
CP
Control Plane
CP-OFDM
Cyclic Prefix-Orthogonal Frequency-Division Multiplexing
CPRI
Common Public Radio Interface
CRC
Cyclic Redundancy Check
CRT
Contention Resolution Timer
CS-RNTI
Configured Scheduling Radio Network Temporary Identifier
CSI
Channel-State Information
CSI-RS
Channel-State Information Reference Signal
CU
Central Unit
DAI
Downlink Assignment Index
dB
Decibel
DC
Dual Connectivity
DCCH
Dedicated Control Channel
DCI
Downlink Control Information
DFT
Discrete Fourier Transform
DFT-S-OFDM
DFT Spread OFDM
DL
Downlink
DL-SCH
Downlink Shared Channel
DM-RS
Demodulation Reference Signals
DRB
Data Radio Bearer
DTCH
Dedicated Traffic Channel
DU
Distributed Unit
E-UTRA
Enhanced Universal Terrestrial Radio Access
E-UTRAN
Enhanced Universal Terrestrial RAN
ECEF
Earth-Centered, Earth-Fixed
ECI
Earth-Centered Inertial
eCPRI
Enhanced CPRI
eDRX
Extended Discontinuous Reception
EIRP
Effective Isotropic Radiated Power
eLTE
Enhanced LTE
eMBB
Enhanced Mobile Broadband
EMF
Electromagnetic Field
eMTC
Enhanced Machine Type Communications
EN-DC
E-UTRAN-NR Dual Connectivity
EPC
Evolved Packet Core
ESIM
Earth Station In Motion
ESOMP
Earth Station On Moving Platform
FCC
Federal Communications Commission
FDD
Frequency Division Duplex
FEC
Forward Error Correction
FFT
Fast Fourier Transform
FoV
Field of View
FR
Frequency Range
FRF
Frequency Reuse Factor
FSS
Fixed Satellite Service
FWA
Fixed Wireless Access
GCI
Geocentric Celestial Inertial
GEO
Geostationary Earth Orbit
gNB
gNodeB
GNSS
Global Navigation Satellite System
GPS
Global Positioning System
GSM
Global System for Mobile Communications
GSO
Geosynchronous Orbit
GTO
Geostationary Transfer Orbit
GW
Gateway
HAPS
High Altitude Platform System
HARQ
Hybrid Automatic Repeat Request
HD
High Definition
HEO
High Elliptical Orbit
HPA
High-Power Amplifier
HPBW
Half-Power Beam Width
I-RNTI
Inactive State Radio Network Temporary Identifier
IAA
Instantaneous Access Area
IAB
Integrated Access and Backhaul
ID
Identity
IE
Information Element
IEEE
Institute of Electrical and Electronics Engineers
iFFT
Inverse FFT
IMT
International Mobile Telecommunications
IoT
Internet of Things
IR
Incremental Redundancy
ISL
Inter-Satellite Link
ISS
International Space Station
ITU
International Telecommunications Union
ITU-R
ITU Radiocommunication Sector
kHz
kiloHertz
L1
Layer 1
L2
Layer 2
LDPC
Low-Density Parity Check
LEO
Low Earth Orbit
LHCP
Left Hand Circular Polarization
LMF
Location Management Function
LOS
Line-of-Sight
LTE
Long-Term Evolution
MAC
Medium Access Control
MBMS
Multimedia Broadcast Multicast Service
MBS
Multicast-Broadcast Services
MCC
Mobile Country Code
MCE
Multicell/Multicast Coordination Entity
MCG
Master Cell Group
MCS
Modulation and Coding Scheme
MDBV
Maximum Data Burst Volume
MEO
Medium Earth Orbit
MHz
Megahertz
MIB
Master Information Block
MIMO
Multiple Input Multiple Output
MME
Mobility Management Entity
mMTC
Massive Machine Type Communications
MN
Master Node
MNC
Mobile Network Code
MNO
Mobile Network Operator
MSG1
Message 1
MSG2
Message 2
MSGA
Message A
MSS
Mobile Satellite Service
MT
Mobile Termination
MTC
Machine Type Communications
NAK
Negative Acknowledgment or Not Acknowledged
NAS
Non-Access Stratum
NB-IoT
Narrowband Internet of Things
NCC
NTN Control Center
NCGI
NR Cell Global Identity
NCI
NR Cell Identity
NDI
New Data Indicator
NE-DC
NR-E-UTRAN Dual Connectivity
NFI
New Feedback Indicator
NG-RAN
Next-Generation Radio Access Network
NGEN-DC
NG-RAN EN-DC
NGSO
Non-Geosynchronous Orbit
NLOS
Non-Line-of-Sight
NNSF
NAS Node Selection Function
NPDCCH
NB-IoT Physical Downlink Control Channel
NPRACH
NB-IoT Physical Random Access Channel
NR
New Radio
NR-U
NR Unlicensed
NRPPa
NR Positioning Protocol a
NSA
Non-Stand-Alone
NSAG
Network Slice AS Group
NTN
Non-Terrestrial Network
NTN GW
Non-Terrestrial Networks Gateway
O-RAN
Open RAN
O&M
Operations & Maintenance
OBP
On-Board Processor
OD
Orbit Determination
OFDM
Orthogonal Frequency Division Multiplexing
OFDMA
Orthogonal Frequency Division Multiple Access
OP
Orbit Prediction
PAPR
Peak-to-Average Power Ratio
PBCH
Physical Broadcast Channel
PCC
Policy and Charging Control
PCCH
Paging Control Channel
PCH
Paging Channel
PCI
Physical Cell Identifier
PDB
Packet Delay Budget
PDCCH
Physical Downlink Control Channel
PDCP
Packet Data Convergence Protocol
PDR
Packet Detection Rule
PDSCH
Physical Downlink Shared Channel
PDU
Packet Data Unit
PHFTI
PDSCH-to-HARQ-Feedback-Timing-Indicator
PHY
Physical Layer
PLMN
Public Land Mobile Network
PLMN ID
PLMN Identifier
PO
Polar Orbit
POD
Precision Orbit Determination
PRACH
Physical Random Access Channel
PSD
Power Spectral Density
PSM
Power Saving Mode
PSS
Primary Synchronization Signal
PT-RS
Phase-Tracking Reference Signal
PUCCH
Physical Uplink Control Channel
PUSCH
Physical Uplink Shared Channel
PV
Position and Velocity
PVT
Position, Velocity, and Time
PWS
Public Warning Service
QAM
Quadrature Amplitude Modulation
QFI
QoS Flow ID
QoE
Quality of Experience
QoS
Quality of Service
QPSK
Quadrature Phase-Shift Keying
RA
Random Access
RAAN
Right Ascension of the Ascending Node
RAN
Radio Access Network
RAO
Random Access Occasion
RAR
Random Access Response
RAT
Radio Access Technology
RB
Resource Block
RE
Resource Element
RedCap
Reduced Capability
RF
Radio Frequency
RHCP
Right Hand Circular Polarization
RIM
Remote Interference Management
RLC
Radio Link Control
RMS
Root Mean Square
RMSE
Root Mean Square Error
RNTI
Radio Network Temporary Identifier
RP
Reference Point
RRC
Radio Resource Control
RRM
Radio Resource Management
RSRP
Reference Signal Received Power
RSRQ
Reference Signal Received Quality
RTD
Round Trip Delay
RTT
Round Trip Time
RU
Remote Unit
RV
Redundancy Version
S-NSSAI
Single Network Slice Selection Assistance Information
SA
Stand-Alone
SAN
Satellite Access Node
SCC
System Control Center
SCG
Secondary Cell Group
SCS
Sub-Carrier Spacing
SDAP
Service Data Adaptation Protocol
SDF
Service Data Flow
SDMA
Space Division Multiple Access
SDO
Standards-Developing Organization
SDT
Small Data Transmission
SDU
Service Data Unit
SFN
System Frame Number
SI
Study Item
SIB
System Information Block
SINR
Signal-to-Interference-Plus-Noise Ratio
SN
Secondary Node
SNO
Satellite Network Operator
SNPN
Standalone Non-Public Network
SON
Self-Organizing Networks
SPS
Semi-Persistent Scheduling
SRB
Signaling Radio Bearer
SRI
Satellite Radio Interface
SRS
Sounding Reference Signal
SS
Synchronization Signal
SSB
SS/PBCH block
SSO
Sun-Synchronous Orbit
SSP
Sub-Satellite Point
SSS
Secondary Synchronization Signal
TA
Timing Advance
TAC
Tracking Area Code
TAG
Timing Advance Group
TAI
Tracking Area Identity
TAU
Tracking Area Update
TB
Transport Block
TC-RNTI
Temporary C-RNTI
tDAI
Total Downlink Assignment Index
TDD
Time-Division Duplexing
TDMA
Time-Division Multiple Access
Te
Transmission Error
TM
Transparent Mode
TM/TC
Telemetry/Telecommand
TN
Terrestrial Network
TNL
Transport Network Layer
TP
Transmission Point
TR
Technical Report
TRP
Transmission and Reception Point
TRS
Tracking Reference Signal
TS
Technical Specification
TSG
Technical Specification Group
TT&C
Telemetry Tracking and Control
TTFF
Time to First Fix
TTI
Time Transmission Interval
UAS
Unmanned Aerial System
UCI
Uplink Control Information
UE
User Equipment
UL
Uplink
UL-SCH
Uplink-Shared Channel
ULI
User Location Information
UM
Unacknowledged Mode
UMTS
Universal Mobile Telecommunications System
UP
User Plane
UPF
User Plane Function
URLLC
Ultra-Reliable, Low-Latency Communications
UTSRP
Uplink Time Synchronization Reference Point
V2X
Vehicle-to-Everything
vLEO
Very Low Earth Orbit
VMR
Vehicle Mounted Relay
VR
Virtual Reality
VSAT
Very Small Aperture Terminal
WG
Working Group
1Introduction
Satellite Communications (SatCom) can be defined as the use of artificial satellites to establish communication links between various points on the Earth's surface, i.e., a telecommunication system encompassing at least one communication satellite. Since the launch of the first artificial satellite (1957, Sputnik 1, Soviet Union), SatCom gained ever-increasing attention, and various artificial satellites have been launched in the following years to provide manyfold services, including communications, navigation, and Earth observation, among others. Figure 1.1 shows the number of launched satellites between 1974 and 2022 per service category; it can be noticed that the number of commercial platforms has always been larger compared to other service categories, and it is still increasing. In some cases, these platforms are multi-mission and also allow to provide government or military applications.
It is also interesting to notice the trends in terms of target orbit. Figure 1.2 shows the number of launched satellites to Geostationary Earth Orbit (GEO), Low Earth Orbit (LEO), Medium Earth Orbit (MEO), and Highly Elliptical Orbit (HEO) since 1974. Initially, taking into account the massive costs involved in both manufacturing and launches, the satellite providers aimed at deploying large platforms at high altitudes, to cover a portion of the Earth as large as possible with as few satellites as possible. In the past years, thanks to the significant advancements in the space industry in terms of on-board capabilities and cost reduction (in particular, thanks to the rise of reusable first-stage rockets), we have witnessed a surge in the research and development of LEO and Very Low Earth Orbit (VLEO) systems, followed by a new space race to mega-constellations (e.g. SpaceX Starlink, OneWeb, and Amazon Kuiper, to name a few).
In parallel to this trend, the past years have also seen significant advancements related to Air-to-Ground (ATG) systems, drones, and High-Altitude Platform Stations (HAPS), initially to support the connectivity to on-ground users in critical scenarios, but now also for many other applications. The combination of the New Space era with the exploitation of low-altitude nodes led to a broadening in the family of communications from the sky: Non-Terrestrial Networks (NTN), which include the use of airborne and spaceborne nodes to establish communication links between various points on the Earth's surface. As shown in Figure 1.3, we now have a continuum of layers/orbits in which NTN nodes can be deployed, allowing terrestrial networks (TNs) to really touch the sky.
Figure 1.1 Percentage of launched satellites per service type between 1974 and 2022.
Source: Adapted from https://www.ucsusa.org/resources/satellite-database.
Figure 1.2 Number of launched satellites per orbit.
Source: Adapted from https://www.ucsusa.org/resources/satellite-database.
Figure 1.3 From SatCom to NTN.
1.1 What is 5G NTN?
Throughout history, legacy SatCom systems have been designed and developed relying on industry-driven technical specifications leading to proprietary architectures, protocol stacks, and radio access solutions, which made the interoperability of the satellite access network between different vendors not granted. This approach of the SatCom Industry leads to a fragmented market with vendor-locked solutions, and limited interworking with mobile systems. With the recent publication of 3GPP technical specifications on the introduction of NTN, a global standard for satellite systems has been newly defined aiming at supporting any orbit, any frequency band, and any device. Such specifications open the door for the seamless integration of airborne and spaceborne network components in the 5G system (5GS) and beyond (including 5G-Advanced and the upcoming 6G), delivering the promise of a ubiquitous mobile system that can support new use cases.
Figure 1.4 Toward a network unifying NTN–TN network components.
As depicted in Figure 1.4, before 3GPP Release-17, 3GPP networks were natively designed and optimized only for terrestrial-based cellular networks. On the other hand, Satellite networks, as previously mentioned, were based on proprietary technologies. Thereby, only limited interworking between SatCom-based networks and 3GPP mobile network components was possible, mainly including backhaul services. The massive 3GPP work on NTN, and the resulting integration of the satellite technology in 3GPP specifications starting from 3GPP Release-17, opened a brand new frontier in 3GPP cellular systems and ushered in new paradigms for connected society, thereby delivering the promise of a ubiquitous end-to-end ecosystem that can support a myriad of new use cases. Here, “integration” means that the space-/air-borne and terrestrial components of the network are able to seamlessly work together to provide coverage continuity to the end users. As the 5G design has originally been optimized for the TN component, a great care has been taken to minimize impacts on User Equipment (UE), 5G Radio Access Network (RAN), and 5G Core (5GC) network level, while supporting the largest range of NTN deployment scenarios.
In order to support such hybrid terrestrial-satellite1 systems enabling New Radio (NR) and Internet of Things (IoT) services through satellites, the 3GPP work started with Study Items (SIs) on NTN in Releases 15 and 16, as shown in Figure 1.5; the necessary features for the support of the NTN component have been then specified as part of the 3GPP Release-17. The Release-17 normative works on NTN and satellites in 3GPP Technical Specification Group (TSG) RAN and TSG Service and system Aspects (SA) have been completed in June 2022 and the related ASN.1 freeze in September 2022 [2]. As previously mentioned, particular attention was given to the minimization of the impacts at UE, NG-RAN, and 5GC levels to support NTN by re-using as much as possible the existing terrestrial-optimized 5G specifications. This first 3GPP NTN standard provides the specifications for 3GPP satellite access networks based on both 5G NR protocols and 4G Narrowband IoT (NB-IoT) and enhanced Machine Type Communications (eMTC) radio protocols; in both cases, the system is operating in Frequency Range 1 (FR1)2 bands. In Release-17, the NR-based satellite access is designed to serve handheld devices to provide enhanced Mobile Broadband (eMBB) services, while the NB-IoT/eMTC-based satellite access aims at providing MTC services to IoT devices for applications in agriculture, transport, logistics, and security markets. To support new scenarios and deployments above 10 GHz, as well as to introduce several enhancements for NR-NTN and IoT-NTN, a normative work is currently being carried out as part of Release-18.
Figure 1.5 3GPP Works on NTN up to Rel-18.
Source: El Jaafari et al. [1].
The support of IoT-NTN is largely aligned with that of NR-NTN in 5GS. It is worthwhile mentioning that, since access networks based on Unmanned Aerial System (UAS), including HAPS and drones, could be considered as a special case of NTN access with lower latencies and Doppler values and variation rates, the main focus is on satellite-based NTN only.
In 3GPP, NTN refers to a network providing non-terrestrial access to UEs by means of an NTN payload embarked on an air-borne or space-borne NTN vehicle and an NTN gateway. A space-borne vehicle can embark a bent-pipe or a regenerative payload telecommunication transmitter, and it can be placed at LEO, MEO, or GEO orbits; an air-borne vehicle is HAPS encompassing UAS, including Lighter than Air UAS (LTA) and Heavier than Air UAS (HTA), all operating in altitudes typically between 8 and 50 km, i.e., quasi-stationary.
Figure 1.6 3GPP defined satellite network solutions for 5G.
Source: El Jaafari et al. [1].
As shown in Figure 1.6, the following satellite network solutions have been integrated within 5GS starting from 3GPP Release-17:
3GPP-defined NR-based satellite access network: NG-RAN based on
satellite access node
s (
SAN
s), connected to a 5GC, providing eMBB via satellite (eMBB-s) and
High Reliability Communication via satellite
(
HRC-s
) services to 3GPP-defined UEs. It supports the 3GPP NR access technology and it may also provide connectivity to
Integrated Access and Backhaul
(
IAB
) nodes.
3GPP-defined LTE-based satellite access network:
Evolved Universal Terrestrial Radio Access
(
E-UTRA
) RAN-based on SANs, connected to an
Evolved Packet Core
network (
EPC
), providing
mMTC via satellite
(
mMTC-s
) services to 3GPP UEs. It supports the 4G NB-IoT/eMTC access technology.
Satellite backhaul: A transport network over satellite that provides connectivity between the 5GC and the gNB, which can be based on 3GPP or non-3GPP-defined radio protocols.
1.2 Use Cases for 5G NTN
The emergence of hybrid terrestrial-satellite systems is the result of a joint effort between stakeholders of both mobile and satellite industries, and it is paving the way to new business opportunities. 3GPP Technical Report (TR) 38.811 [3], reports the identified use cases for the provision of services when considering the integration of the NTN access component in the 5GS; a more detailed description of each use case can be found in 3GPP TR 22.822 [4]. The identified use cases benefit from the wide service coverage capabilities and the reduced vulnerability provided by the space-/air-borne nodes of the NTN component to physical attacks and natural disasters. In general, they can be categorized into the following three macro-usage scenarios:
Service ubiquity and global connectivity: This category targets the reduction of the digital divide by providing direct access connectivity to handheld terminals, households, and IoT devices. This scenario will complement the TN in under-served or un-served geographical areas. Some uses cases that fall into this category include direct access to smartphone and home access in rural or isolated areas,
Public Safety and Public Protection and Disaster Relief
(
PPDR
) in remote areas or areas that experienced a disaster (for instance, earthquakes, floods, or terrorist attacks) leading to a partial or total destruction of the terrestrial infrastructure, IoT for agriculture, critical infrastructures metering and control–pipelines, and asset tracking/tracing.
