The Integrated Access Backhaul (IAB) is deemed to reduce the deployment costs of ultra-dense 5G millimetre-wave (mmWave) networks, using wireless backhaul links to relay the access traffic. ESA funded the project SATIABLE to investigate technical issues to use the satellite for this kind of service, aiming to draw recommendations for IAB features or extensions for scenarios integrating NTN networks, to provide an analytical baseline and a simulation tool for the assessment of benefits for further studies towards the 3GPP Release 18. The paper briefly describes the project objectives and outcomes.

As the telecommunications industry embarks on the transition to Sixth-Generation (6G) networks, this paper examines the integration of Non-Terrestrial Networks (NTN), and in particular satellite backhauling, in the context of Fifth-Generation (5G) systems. The Integrated Access and Backhaul (IAB) technology, conceived as a wireless terrestrial backhauling system in the Next Generation Radio Access Network (NG-RAN), has been identified as a possible enabler for the integration of satellite nodes. Despite the work already done in this direction, the combination of IAB architectures with satellite nodes operating in both the access and backhaul side requires further evaluations on feasibility and limitations for networks integrating Low Earth Orbit (LEO) and Geostationary Earth Orbit (GEO) satellites. To this end, this work contributes providing insights on background technologies, as well as a detailed analysis of the issues and challenges arising from such integration and a definition of use cases to support narrow-band and broadband services. Furthermore, the design and implementation of a simulation tool is proposed for a performance evaluation in terms of registration time, link capacity, single-hop and end-to-end delay. Results show that the integration turns out to be feasible, even if with strong constraints coming from the satellite system rather than the IAB usage itself. Indeed, the earth-satellite link in LEO systems has a significant impact on the packet delivery time due to the discontinuous coverage. In case of GEO satellite instead, a non-terrestrial backhaul link could limit the performance of the whole system, especially at lower elevation angles.

Reliable communications play a pivotal role in ensuring an efficient response and the coordination of recovery and rescue efforts. However, conventional communication methods may not always be accessible or dependable in such situations. In such circumstances, constellations of Low Earth Orbit (LEO) satellites can provide high bandwidth capabilities with relatively low latency, making them well-suited for supporting on-the-ground disaster management teams. Satellites can either complement or replace terrestrial telecommunication infrastructures. In this context, reliance on the recently defined QUIC protocol allows for a seamless transition from terrestrial to satellite communication as needed. Therefore, we investigate the possible use of a dual-stack node architecture along with the employment of the QUIC transport protocol for emergency communications, assuming that the backhaul link used to transfer users’ applications data may need to be changed (seamlessly). We conduct an extensive emulation study, evaluating the performance of QUIC under varying queuing policies and Congestion Control Algorithm (CCA) behaviour, providing practical insights and recommendations to enhance the protocol’s efficiency and robustness. The key aspects and configurations of QUIC protocol stack are identified, presenting optimal communication configurations leveraging CoDel and BBR CCA.

The 3GPP standardized a new architecture and procedures for the NG-RAN to extend the network coverage to those hidden or unreachable areas. It consists in a distributed topology of low-complexity and low-cost network nodes named Integrated Access and Backhaul (IAB). The IAB is defined in Rel-16 and enhanced in Rel-17 and allows to distribute the gNB element in multiple Distributed Units (nodes) controlled by a Central Unit (donor) directly connected with the core network. This architecture is designed to relay the radio signal of the UE leveraging a wireless backhaul. Furthermore, enhancements for the mobile-IAB are expected in the Rel-18, in particular assuming nodes mounted on top of moving vehicle which can be either Terrestrial or Non-Terrestrial. Similarly, the 3GPP published a study which identified some appealing use cases where Non-Terrestrial Networks (NTN), in particular the satellite, can be exploited to relay the radio signal of the UE in areas unserved or uncovered by Terrestrial networks. The integration of a satellite component in this scenario may be a further confirmation of its added value and the support that could be provided in mobile networks. First steps were already moved with the definition of two frequency bands for the Satellite Access Node (SAN) operations by 3GPP in Rel-17, while further enhancements are expected for 6G networks. This paper briefly reports the key aspect of the IAB technology and will investigate possible architectures including a satellite components. Two main integration approaches will be evaluated analysing possible adaptations required for SatCom in direct access.

5G aims at providing significant improvements to mobile networks with regard to previous 4G ones, in both performance and flexibility. Indeed, a 5G network is expected to increase throughput and reduce latency, leveraging softwarization and virtualization concepts and the state of the art in radio access and resources allocation. A 5G system (5GS) long-term goal is to address more and more challenging and broader use-cases, allowing a multi-tenant use (slicing) of the same physical infrastructure to enable and deploy at the same time ultra-reliable and low latency, machine-type or broadband communication services. In that context, network resources are highly abstracted and require complex management operations, which ultimately must be reflected downwards to the physical resources. In supporting that task, since 3GPP Rel-16, a network function called Network Data Analytics Function (NWDAF) was introduced, with the primary goal of collecting and processing heterogeneous data coming from the User Plane of the 5GS. The NWDAF outputs can then be used to perform network reconfigurations and automation in general, optimizing traffic management and overall network performance. In this paper we present which realtime metrics can be collected by a NWDAF and how, in a reference 5G core network, validating the correctness of the measurements performed using real traffic in a Linux-based testbed.

5G represents the latest currently available and the state of the art of mobile cellular networks. 5G is defined on the basis of new concepts like Software Defined Network (SDN), Network Function Virtualization (NFV) and Network Slicing, enabling a wide set of use-cases and applications. An innovative feature introduced in 5G since 3GPP Release 16 is Access Traffic Steering, Splitting and Switching (ATSSS), which gives the possibility to the user equipment (UE) connected to a 5G network using a 3GPP link (i.e., the gNB New Radio access) and a non-3GPP one (e.g., a public WLAN access point) to access 5G services using both links simultaneously. ATSSS can improve the user-experience, maximizing the throughput and improving resilience to network faults by downloading or uploading data using both channels at the same time or selecting the best link where to transmit for each data flow. In this paper, we analyze in depth the ATSSS functionality and the associated Multipath TCP (MP-TCP) mode in a Linux simulation testbed, including an Open Source 5G Core Network, with the full implementation of the User Plane and 3GPP and non-3GPP access links, using Free5GC, UERANSIM and a custom implementation of N3IWF. In this testbed setup, we run real traffic and assess the MP-TCP configuration and performance in realistic conditions, when the non-3GPP access is performed wither via terrestrial wireless or a high latency satellite link.

The 5G service-based architecture brought a high degree of flexibility in the dynamic network management and configuration, enabling several Network Functions (NFs) cooperating to customize a communication service based on requirements of a specific vertical. Since rel. 15, the 3GPP introduced a Network Data Analytic Function (NWDAF) for the collection of data from other NFs and the delivery of data analytics services. This paper addresses a compelling use case with a hybrid satellite terrestrial backhaul, with the NWDAF that can be used to catch the slice statistics on the user plane and to drive the enabling of a supplementary satellite backhaul link for performance optimization in compliance with the service requirements. Thus, an optimized configuration of the 5GC is proposed highlighting the NFs involved in the analytics as well as the data sources and the data interfaces.

5G is a cornerstone in the evolution of mobile communication networks, representing the most advanced and available standard at the state of art. Characterized by higher data rate and capacity, actually the real revolution of 5G relies in its capability to offer advanced and heterogeneous services by the full abstraction and slicing of network resources, realizing a service-oriented full-IP high-performance network over a common infrastructure, even belonging to different operators. Another key aspect, which is specifically addressed in this paper, is the possibility to access the services offered by the 5G network using non-3GPP access, and in particular Wi-Fi. This feature can allow access from home Access Points or using public Hotspots, even where there is no 5G coverage or roaming. At the same time, other types of IP access, including terrestrial wired options, are allowed by 3GPP specifications. Such a flexibility allows, although not explicitly mentioned, to consider as well satellite-based non-3GPP access methods, thus enabling wide-coverage use-cases and rural areas coverage. In the paper we discuss the network function required to enable non-3GPP access to 5G Core Networks, namely N3IWF, and the impact in using as access network a VSAT satellite link. After a focus on protocol stacks and signalling procedures, we implemented such an access on a real time Linux testbed including a 5G rel. 15 compliant Core Network, a N3IWF network function and a satellite emulation to assess control procedures timings, User plane latency and overhead.

The adoption of the Narrowband-Internet of Things technology in satellite communications intends to boost Internet of Things services beyond the boundaries imposed by the current terrestrial infrastructures. Apart from link-level studies in the scientific literature and preliminary 3GPP technical reports, the overall debate is still open. To provide a further step forward in this direction, the work presented herein pursues a novel service-oriented methodology to design an effective solution, meticulously stitched around application requirements and technological constraints. To this end, it conducts link-level and system-level investigations to tune physical transmissions, satellite constellation, and protocol architecture, while ensuring the expected system behavior. To offer a real smart agriculture service operating in Europe, the resulting solution exploits 24 low-Earth orbit satellites, grouped into eight different orbits, moving at an altitude of 500 km. The configured protocol stack supports the transmission of tens of bytes generated at the application layer, by also counteracting the issues introduced by the satellite link. Since each satellite has the whole protocol stack onboard, terminals can transmit data without the need for the feeder link. This ensures communication latencies ranging from 16 to 75 min, depending on the served number of terminals and the physical transmission settings. Moreover, the usage of the early data transmission scheme reduces communication latencies up to 40%. These results pave the way toward the deployment of an effective proof of concept, which drastically reduces the time to market imposed by the current state of the art.

Satellite communications (SatCom) have a role of advanced service enablers in the new virtual networks, following 3GPP specifications. Specifically, the satellite peculiar characteristics are of paramount importance to dynamically activate capabilities, such as multicast and broadcast channels, sudden traffic offloading, capacity bonding, and cost-efficient coverage of uncovered areas. A key aspect to achieve a seamless and efficient integration between satellite and terrestrial infrastructures is to make satellite resource management dynamic and with a centralised control of a single orchestrator that has visibility of the end-to-end network. Considering the adoption of Software Defined Networking (SDN) and Network Function Virtualization (NFV) paradigms and the upcoming 5thgeneration of mobile communications (5G), this paper presents the ongoing work within the European Space Agency (ESA) ANChOR project, whose main output will be a data-driven Network Controller and Orchestrator for SatCom networks. This tool will be based on Artificial Intelligence (AI) / Machine Learning (ML)-based techniques to properly allocate resources exploiting some feedback knowledge of the network and it aims to support different services over 5G integrated satellite-terrestrial networks.

The management of public utilities represents a complex issue even in normal operational conditions. In case of emergency the degree of complexity increases exponentially and the variables to take into account, the data to process, the useful expected outcomes and the decision processes need to be supported by technology.For these reasons, the eUmaP project aims to design and develop an open platform through which local authorities will be able to plan and manage the demand and supply of building utilities in case of quarantine or lock down. It will be based on the rational of Earth observation, and the recording of the required network information in open BIM platforms of five European capital cities (Rome, Berlin, Athens, Vilnius, Nicosia).The paper is focused on the architecture definition discussing the pros and cons of three different architectural schemes.

The advent of 5G with the three identified use case classes (eMBB, mMTC, URLLC) requires to adequately define system architectures including all the technological segments that can contribute to satisfactorily reach the target performance. For this reason, satellite systems must be duly considered because their intrinsic characteristics are well suitable to support 5G services. In particular, as concerns mMTC/NB-IoT class an ongoing ESA project is demonstrating the feasibility and the usefulness of the inclusion of the satellite segment in the system architecture and has identified peculiar use cases. The paper presents some of the outcomes of the project so far achieved, both in terms of scenario identification and implementation issues in compliance with 3GPP standard architectures.

The QUIC (Quick UDP Internet Connection) protocol suite is going to approach its final stages of standardization to become part of the official Internet standards (RFCs) and of the new HTTP/3 specification. Some of its disruptive characteristics, such as the 0-RTT establishment of secure communications and a connection-oriented management over a UDP-based connection-less transport, can be reused and tailored in the framework of a Performance Enhancing Proxy (PEP) architecture for the effective management of multiple links. In this paper, we describe the design and implementation of a QUIC-based splitting solution to enhance the communication across multiple backhaul links, each associated with a different network technology (e.g., satellite and terrestrial). After discussing the working principles of the designed QUIC-based proxy, we present a software implementation, as well as preliminary results obtained, through a set of meaningful test-cases deployed over a Linux based testbed.

In the definition of advanced 5G scenarios, one of the possible configurations including the satellite link is to consider it to provide a supplementary capacity to enhance backhauling towards data networks. The peculiar satellite physical characteristics and the resulting challenging communication environment (i.e., large propagation delays, possible losses, etc.) are usually tackled with the introduction of Performance Enhancing Proxies (PEPs) agents aimed to improve performance. In this regard, 5G offers the cutting-edge capability to exploit virtualization and slicing concepts, so that PEP can be implemented as a set of Virtualized Network Functions (VNFs) to be dynamically deployed into the network responding to the specific requirement of the target service slice. In this paper we discuss this approach, validated in the frame of an European Space Agency (ESA) project, where a hybrid terrestrial-satellite backhaul is envisaged to enhance performance and system. In particular, we present a QUIC proxy as distributed VNFs aimed to efficiently manage the hybrid link allowing an efficient failover in case of terrestrial link outage or unavailability.