Editorial for Wiley's IJSCN Special Issue “Satellite networks integration with 5G”

Abstract

As such, the 5G ecosystem opens up an opportunity to integrate terrestrial and satellite systems in order to achieve the goal of the attributes mentioned above (i.e., global seamless connectivity, ubiquity, coverage, security, and resiliency) across the family of 5G use cases—eMBB, URLLC, and mMTC. It is not only throughput and ubiquity that are crucial; latency and reliability are now becoming important metrics in future systems to provide acceptable quality of experience (QoE) across use cases. To this end, the Third Generation Partnership Project (3GPP), as part of the 5G set of standardizations, has started working on Non-Terrestrial Networks (NTN) from Release 16 of the 5G standards, which includes satellites as well as high-altitude platform systems (HAPS) and unmanned aerial systems/vehicles (UASs/UAVs). In addition, various pre-commercial pilot deployments and over-the-air tests for satellite integration into 5G are being conducted worldwide. Moreover, several recent research, development, and innovation projects have been investigating the integration of satellites in 5G and have conducted several successful over-the-air demonstrations and validation campaigns paving the way for the seamless satellite integration into 5G. These recent activities—with the active involvement of the satellite and terrestrial mobile industry stakeholders—have resulted in inclusion of 5G features in satellite and non-terrestrial networks and their necessary integration and validation tests. Large-scale 5G testbeds have been developed to validate the end-to-end terrestrial-satellite 5G integrated system and their network performance and to demonstrate the seamless service delivery. The ability to achieve full network convergence is predicated on software-defined network (SDN) design and network function virtualized (NFV) elements which can be orchestrated to form an end-to-end virtualized network, including both terrestrial and satellite elements. Moreover, new networking paradigms can now allow more efficient resource allocation schemes on an end-to-end basis with clear implications on the implementations and orchestration in both ground segment (e.g., radio access network [RAN], satellite hub stations, and core network) and space segment (e.g., onboard satellite payloads, HAPS, and UAS). In parallel, progress is being made to enhance the physical layer performance with novel interference mitigation/management and multiple access techniques coupled with the design of smarter antennas and multi-antenna signal processing. The aim of this special issue has been to solicit and present advances in satellite and terrestrial networking technologies illustrating the many areas where 5G and satellites can be suitably and efficiently integrated in a unique system platform. As such, the papers presented in this special issue bring a sound balance between academic research and industrial development in order to provide a reference point for the know-how in this sector. In particular, this special issue includes nine original innovative papers which are overviewed hereinafter. In Paper 1—“Techno-economic analysis of inflight connectivity using an integrated satellite-5G network”, the authors present a techno-economic analysis conducted within the EU H2020 5GPPP project “SaT5G” (Satellite and Terrestrial network for 5G) for in-flight connectivity using an integrated satellite–5G network. The demand for mobile broadband services is increasing exponentially alongside with user expectations regarding the reachability of these services and their prices. This paper presents an integrated satellite and 5G network for providing in-flight connectivity and evaluates the economic viability of offering broadband connectivity to passengers on commercial airplanes by the development of a techno-economic framework. Results show that satellite bandwidth usage leads to high operational costs. Therefore, caching popular content on the network onboard is beneficial to reduce the traffic carried over the satellite link. Furthermore, the framework is used to compare the identified business models for in-flight connectivity and their pricing strategies. Finally, a sensitivity analysis is elaborated in order to mitigate the uncertainty of inputs (e.g., rate of caching) used to feed the total cost of ownership (TCO) model. The following concrete recommendations are the main result of this research: (i) providing in-flight broadband services with a 2- to 5-Mbps throughput per user is feasible with a satellite and 5G integrated network; (ii) caching popular data reduces the operational costs and the average cost per user (from 25% to 32% depending on the caching rate adopted); and (iii) this framework allows to provide recommendations on the best suited business models and related pricing schemes. In Paper 2—“An extensible network slicing framework for satellite integration into 5G”, the authors address an extensible network slicing framework for satellite integration into 5G. With the imminent deployment of 5G in the non-standalone version, some researches focus on network slicing to fully exploit the 5G infrastructure and achieve a high level of flexibility in the network. This level of flexibility offered by the network slicing paradigm also fits the need of satellite networks in which satellite network operators want to offer 5G connectivity services additionally to the traditional satellite connectivity. However, the work that has been done so far for network slicing in 5G does not directly apply to satellite networks due to satellite architecture specificities and thus needs to be extended. In this paper, the work on network slicing is extended and a novel satellite slicing framework is proposed in order to fully exploit the satellite infrastructure and to facilitate the integration of satellite services into 5G. Such framework includes definition, modeling, orchestration, and deployment of multiple satellite network slices and their associated network services on top of mutualized satellite infrastructures. In Paper 3—“An integrated satellite–terrestrial 5G network and its use to demonstrate 5G use cases”, the authors address an integrated satellite–terrestrial 5G network and its use to demonstrate 5G use cases developed within the EU H2020 5GPPP project “SaT5G” (Satellite and Terrestrial network for 5G). The testbed's 3GPP Rel 15/6-compliant mobile core and RAN are first presented. It is then detailed how satellite NTN UE and gateway elements were integrated into the testbed using virtualization and software-defined orchestration. The satellite element provides 5G backhaul, which in concert with the terrestrial/mobile segment of the testbed forms a fully integrated end-to-end 5G network. The resulting hybrid 5G network is then used to validate the four major use cases defined within the SaT5G project: cellular backhaul, edge delivery of multimedia content, multicast and caching for media delivery, and multilinking using satellite and terrestrial. The multi-access edge computing (MEC) implementations developed to address each of the aforementioned use cases are described, and it is explored how each MEC system integrates into the 5G network. Measurements from trials of the use cases over a live GEO satellite system are also provided, and in each case, the improvements that result from the use of satellite in the 5G network are indicated. In Paper 4—“Satellite integration into 5G: accent on testbed implementation and demonstration results for 5G Aero platform backhauling use case”, the authors address the testbed implementation and present demonstration results of tests conducted within the EU H2020 5GPPP project “SaT5G” (Satellite and Terrestrial network for 5G) for a 5G aeronautical platform backhauling use case. The SaT5G project addressed the plug-and-play integration of satellite communication into 5G. One of the SaT5G use cases corresponds to the delivery of 5G connectivity services to moving platforms such as aircraft via geostationary (GEO) and medium Earth orbit (MEO) satellite backhauling. With focus on this use case, this paper elaborates on the practical implementation and measurement results obtained within the 5G Aero testbed developed as part of the SaT5G project. The 5G Aero testbed activities focus on the next generation of connectivity and content distribution services to airplanes through satellite and terrestrial integration in 5G at the user, control, and management planes. SDN and NFV are key enablers to develop a powerful end-to-end testbed that can accelerate the adoption of MEC for the next-generation In-Flight Entertainment and Connectivity (IFEC) services, which use GEO and MEO satellite backhauling technologies. Hence, measurement results obtained from both over-the-air demonstration over the O3b MEO satellite constellation and in-lab validation over an emulated GEO satellite link are presented, towards the next-generation 5G-enabled IFEC services. In Paper 5—“5G-VINNI use cases and testbed solutions for 5G cellular backhauling via satellite”, the authors address the use cases and testbed solutions developed within the EU H2020 5GPPP project “5G-VINNI” (5G Verticals Innovation Infrastructure) for 5G cellular backhauling via satellite. It presents the end-to-end design of the 5G-VINNI Norway and Luxembourg Facility Sites, which are currently under development and aim to showcase the satellite integration into 5G with focus on satellite backhauling solutions. It elaborates on the satellite transport network between the 5G RAN and the 5G Core Network (5GC), where design aspects on the satellite network integration into the standard 3GPP 5GC architecture are detailed. It also addresses the split of the 5GC between the central node and the edge node, where the edge node can be fixed and nomadic. The paper describes also the management and orchestration (MANO) and network functions virtualization infrastructure (NFVI) features of the 5G-VINNI Norway and Luxembourg Facility Sites. In Paper 6—“Emergency 5G communications on-the-move: concept and field trial of a mobile satellite backhaul for public protection and disaster relief”, the authors address a concept and field trial of a 5G-enabled satellite communications on-the-move solution for the Public Protection and Disaster Relief (PPDR) vertical market. A secure and flexible communication infrastructure for the use of broadband and IP-based services is becoming more and more important in the context of PPDR. Government agencies and emergency responders need to be able to react quickly to emergencies across the globe. In particular, satellite-based 5G mobile networks can support government agencies during their critical tasks. In order to support the standardization committees and the industry, it is required to evaluate new architectures for such networks by utilizing testbeds and field trials. In this article, the authors propose and investigate architectures for mobile PPDR networks with satellite backhaul to ensure Communication on-the-Move (COTM). The flexibility within the architectures comes with the distribution of the core network nodes at the edge of the network applying the Core-Edge Split concept. The presented results show that existing interfaces of the Evolved Packet Core 3GPP standard allow satellite-based 5G networks to be tailored to the needs of government authorities. In Paper 7—“5G satellite networks for IoT: backhauling and offloading”, the authors focus on the use of low-Earth orbit (LEO) satellite constellations for two specific purposes towards Internet of things (IoT): offloading and backhauling. The connection of IoT devices is one of the main drivers of 5G cellular networks. To achieve anytime, anywhere IoT connectivity, the next leap is to integrate NTN into 5G terrestrial systems to extend the coverage and complement the terrestrial service. Offloading allows offloading IoT traffic from a congested terrestrial network, usually in a very dense area. With respect backhauling, the constellation provides a multi-hop backhaul that connects a remote terrestrial gNB to the 5G core network. After providing an overview of the status of the 3GPP standardization process, the user data performance is modeled and analyzed in both cases, specifically in the uplink access and the satellite multi-hop constellation path. The evaluation of the collisions, the delay and the Age of Information, and the comparison of the terrestrial and the satellite access networks provide useful insights to understand the potential of LEO constellations for offloading and backhauling. In Paper 8—“Integrating the 5G NR and satellite systems: main features, needed changes, and performance results”, the authors address the recent developments conducted within the EU H2020 5GPPP project “SaT5G” (Satellite and Terrestrial network for 5G) towards integrating the air interface of satellite communications into the upcoming 5G new radio (NR) systems. In particular, the focus is on harmonizing the physical (PHY) and medium access control (MAC) layers of both satellite and 5G NR systems by first identifying key features and incompatible procedures and then proposing suitable solutions to successfully integrate satellite and terrestrial networks. Moreover, proper use cases are defined and evaluated by means of computer simulations, as well as analytical models. In Paper 9—“Licensed shared access (LSA) field trial and a testbed for 5G and beyond satellite-terrestrial communications”, the authors address a licensed shared access (LSA) field trial using live 5G networks in the spectrum sharing scenario between satellite and cellular networks. The trial focuses on 5G pioneer bands 3.4–3.8 and 24.25–27.5 GHz where the satellite system is operating in the downlink direction and a cellular system is accessing the same band. The performance evaluation in the trial concerns evacuation and frequency change times using different types of base stations, that is, how fast the system relinquishes the shared band to the primary user and continues transmission using other bands. It is shown that the proposed LSA system is scalable and able to support large number of base stations. In addition, it is investigated how satellite systems could reuse International Mobile Telecommunication (IMT) bands to offer enhanced satellite communication services for land, maritime, and aeronautical applications. Preliminary simulations and analysis confirm the possibility to reuse IMT spectrum for satellite systems without causing harmful interference, both with a satellite band allocation in the same and in the opposite direction from the terrestrial system. The above papers have already produced results and recommendations which have been contributed to the 3GPP Rel 16 study work on NTN. Most of the existing work has concentrated on satellite backhaul applications and on eMBB use cases. 3GPP Rel 17 extends this work to mMTC (NB-IoT) and URLLC use cases. In addition, the direct satellite access to terminals via 5G NR air interface, which is addressed in one of the papers in this special issue, is receiving attention in 3GPP. This is perhaps particularly relevant to the non-GEO satellite constellations that are now starting to appear. The emphasis thus far has been on research and demonstration of key techniques and technologies to demonstrate that an integrated satellite–terrestrial 5G solution is feasible. Progress will continue to be made via 3GPP Rel 17 onwards, towards standards for commercial availability in the next couple of years.