Page 48 - Kaleidoscope Academic Conference Proceedings 2022

2022 ITU Kaleidoscope Academic Conference

organizations. It empowers network service providers to The European Space Agency (ESA) funded project
offer high quality services and seamless mobility from a TN “Demonstrator for satellite-terrestrial integration in the 5G
to NTN and vice versa. context (SATis5)” has aimed to build a large-scale, live,
proof-of-concept testbed of 5G integrated satellite-
The remainder of this paper is organized as follows. Section terrestrial networks [6]. The testbed is used to demonstrate
2 discusses related research, development, and the applicability of satellite technology to realize the 5G use
standardization activities. Section 3 presents scenarios of cases of enhanced Mobile Broadband (eMBB) and massive
TN and NTN convergence in the control plane. Section 4 Machine-Type Communication (mMTC) services.
describes the functional architecture of integrated and
individual network control systems for TN and NTN Research projects related to TN and NTN convergence are
convergence. Section 5 concludes the paper by listing also progressing in Japan. In the Beyond 5G/6G whitepaper
future work items. published by the National Institute of Information and
Communications Technology (NICT) recently [8], TN and
2. RELATED WORK NTN convergence has been considered a key technological
innovation for serving the future society of 2030s and
Non-terrestrial networks, composed of satellites, HAPS and beyond. TN and NTN convergence has been considered
drones, will have the capability of offering communication indispensable for the realization of three novel use-case
services on a large scale because of their wide coverage scenarios of the future society, namely, cybernetics avatar
around the world and robust multilink transmission society, city on the moon, and transcending space and time.
capability. High-Throughput Satellites (HTS) are being Similarly, the Space ICT Promotion Initiative Forum (SPIF)
developed for the extension of an urban 5G system’s small [9] has been promoting the multifaceted development of
cell coverage to rural and remote areas. Although satellite space-related communication technologies and applications
communications in the past used to be for specific purposes by establishing a close collaboration between industry,
such as television broadcasting or international telephone academia, and government. It is channeling Japan’s
trunk lines, recent deployments of very high throughput collective efforts on sharing information on the latest
GEO satellites and LEO satellite constellations have technological and application development trends,
extended their usage to general purpose telephony and data identifying cooperation/competition areas, and examining
communication services [3]. various strategies.

Worldwide efforts of research, development, and SDOs are also actively progressing the standardization of
standardization of TN and NTN convergence technologies TN and NTN convergence technologies. In ITU, the
have been progressing rapidly. The European Commission scenarios of satellite access integration with terrestrial
(EC) has recently funded several projects to investigate TN networks were discussed by using the term ManyNet under
and NTN integration issues and develop suitable solutions. the activities of Focus Group on Technologies for Network
The project named “Satellite and terrestrial networks for 5G 2030 (FG-NET2030) [10]. Recently, ITU-T Study Group
(SaT5G)” [2] has investigated the extension of Network 13 has started the study of requirements, capabilities,
Function Virtualization (NFV) and Software-Defined interfaces, service continuity, and procedures for fixed,
Networking (SDN) capabilities to satellite network mobile and satellite convergence in networks beyond IMT-
configuration and management. It has proposed technology 2020 [11].
for seamlessly integrating NTN into the 5G Management
And Orchestration (MANO) system, while addressing the 3GPP has published several related technical reports. 3GPP
issues of multi-links, heterogeneous transport, control and TR 22.822 presents a study on using satellite access in 5G
user planes harmonization, security, caching, and multicast. systems [12]. It describes twelve use cases by categorizing
Similarly, another project named “5G agile and flexible them into three groups (i.e. service continuity, ubiquity, and
integration of satellite and cellular (5G- ALLSTAR)” has scalability) and drawing several requirements from each use
investigated the issues of multiple access when combining case. 3GPP TR 28.802 discusses the management aspect of
cellular and satellite access technologies for reliable, satellites in 5G [13]. It identifies the issues associated with
ubiquitous broadband services [4]. More specifically, it has service and network management of satellite integrated 5G
explored a set of technologies such as new radio-based and presents a reference architecture for management and
satellite access, multi-connectivity, and spectrum sharing the associated solutions. 3GPP TR 23.737 presents a study
between cellular and satellite systems to provide global on architecture aspects for satellite access in 5G [14]. It has
connectivity and support mission critical applications. identified the impact areas and solutions (including
Similarly, the project named VITAL (Virtualized hybrid procedures) for resolving radio access and core network
satellite-terrestrial systems for resilient and flexible future related issues. Similarly, ETSI TR 103 611 presents the
networks) has studied the federated resource management various integration scenarios of NTN in 5G systems and
of hybrid satellite-terrestrial networks by applying NFV and related architecture options [15].
SDN in satellite networks [5]. It has studied three scenarios
of virtualization and sharing of satellite communication Several academic research papers published recently have
resources, 5G backhauling services, and federated satellite- also discussed the diverse aspects of TN and NTN
terrestrial access services. convergence. A comprehensive survey of the state-of-the-

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