Non-Terrestrial Networks Research Articles

A systematic literature review on the role of UAV-enabled communications in advancing the UN’s sustainable development goals

Unmanned Aerial Vehicles (UAVs), commonly known as drones, show great potential in advancing the United Nations (UN) Sustainable Development Goals (SDGs), a collection of 17 worldwide targets outlined by the United Nations (UN) to tackle diverse social, economic, and environmental issues and foster sustainable development by 2030. As per the Federal Aviation Administration (FAA), UAVs can significantly improve areas of sustainability like wildlife and wildfire monitoring, precision agriculture, as well as healthcare. Furthermore, drones with communication capabilities are seen as key elements of non-terrestrial networks, and as enabling technologies for future 6G communication networks. This systematic literature review focuses on the role of UAV-enabled communications to achieve the SDGs. Our study is based on a thorough selection and analysis of scientific articles. Initially, we performed a broad search across three major databases: IEEE Xplore, Web of Science, and Scopus, yielding a set of 10,499 papers. Following a strict selection methodology (Preferred Reporting Items for Systematic Review and Meta-Analysis - PRISMA), we narrowed this set down to 28 key journal articles. Our analysis highlights six global targets that greatly benefit from UAV-enabled aerial communication. In order of impact, these are: “Sustainable Cities and Communities,” where UAVs improve security and disaster management; “Life on Land,” where drones help with wildlife monitoring and reforestation; “Industry, Innovation, and Infrastructure,” where UAVs (Unmanned Aerial Vehicles) aid in infrastructure inspection; “No Hunger,” where drones improve agricultural practices; “‘Good Health and Wellbeing,” where UAVs assist with disease prediction and monitoring; and “Clean water and sanitation,”where drones play a crucial role in efficiently monitoring water quality and distribution. In summary, this paper offers a detailed look at the applications of UAVs in achieving the SDGs through aerial communications. By identifying areas of major impact and spotting gaps and weaknesses in current research, this review article aims to guide future research and policy-making in sustainable drone applications.

Regulatory and spectrum policy challenges for combined airspace and non-terrestrial networks

The recent advancements in the aviation and space industries facilitate new types of users in the sky, e.g., electrical vertical take-off and landing (eVTOL) aircraft. To unlock the full potential of these innovations, it is crucial to create interconnected three-dimensional networks that integrate airspace and non-terrestrial networks (NTNs) with their terrestrial counterparts, also known as Combined Airspace and Non-Terrestrial Networks (ASN). Combined ASN needs a flexible and adaptive network architecture with multiple, and partly converging technologies, such as air-to-ground, satellite, and high-altitude platforms, with a focus to cover both ground and aerial users. In addition to technical challenges, spectrum policy and regulatory aspects will affect the wireless network design and management schemes in three-dimensional space. Hence, this paper introduces regulatory and spectrum policy challenges posed by the development of combined ASN. This paper investigates a hypothetical urban air mobility use case with an eVTOL aircraft that operates as a flying taxi.

Enhancing Service Continuity in Non-Terrestrial Networks via Multi-Connectivity Offloading

Enhancing Service Continuity in Non-Terrestrial Networks via Multi-Connectivity Offloading

Preamble Design and Detection Based on Sequence Selection Pattern for Random Access in Non-Terrestrial Networks

Preamble Design and Detection Based on Sequence Selection Pattern for Random Access in Non-Terrestrial Networks

5G Non-Terrestrial Networks: Technologies, Standards, and System Design

5G Non-Terrestrial Networks: Technologies, Standards, and System Design

Guard Band Protection Scheme to Facilitate Coexistence of 5G Base Stations and Radar Altimeters

Reformation of the 3.7–4.0 GHz band to expand 5G communication deployment poses a risk of 5G signals disrupting radar altimeter operation, leading to data loss or inaccuracies. Thus, this paper proposes a guard band protection method to facilitate the coexistence of 5G base stations and radar altimeters operating in the 4.2–4.4 GHz band. To enhance the adjacent channel leakage ratio (ACLR), we implemented spectral regrowth on an oversampled waveform using a high-power amplifier model, filtering out-of-band spectral emissions. The results demonstrated that a 150 MHz guard band enables coexistence, except in the case of the 16-by-16 antenna array in rural environments. Notably, for the 4-by-4 antenna array in urban environments, coexistence can be achieved using a 50 MHz guard band. The proposed mitigation techniques may also be extended to promote coexistence between non-terrestrial networks and 5G communication systems, including satellites, unmanned aerial vehicles, and hot air balloons.

Integrating terrestrial and non-terrestrial networks via IAB technology: System-level design and evaluation

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.

Exploiting stream scheduling in QUIC: Performance assessment over wireless connectivity scenarios

The advent of wireless technologies has led to the development of novel services for end-users, with stringent needs and requirements. High availability, very high throughput, low latency, and reliability are all of them crucial performance parameters. To address these demands, emerging technologies, such as non-terrestrial networks or millimeter wave (mmWave), are being included in 5G and Beyond 5G (B5G) specifications. mmWave enables massive data transmissions, at the expense of a more hostile propagation, typical for high frequency bands. Consequently, the inherent instability of the physical channel significantly affects the upper layers of the protocol stack, resulting in congestion and data losses, which might strongly hinder the overall communication performance. These challenges can be addressed not only at the link layer, but at any affected layer. QUIC is a new transport protocol designed to reduce communications latency in many ways. Among other features, it enables the use of multiple streams to effectively manage data flows sent through its underlying UDP socket. This paper introduces an implementation of priority-based stream schedulers along with the design of a flexible interface. Exploiting the proposed approach, applications are able to set the required scheduling scheme, as well as the stream priorities. The feasibility of the proposed approach is validated through an extensive experiment campaign, which combines Docker containers, the ns-3 simulator and the Mahimahi framework, which is exploited to introduce realistic mmWave channel traces. The results evince that an appropriate stream scheduler can indeed yield lower delays for time-sensitive applications by up to 36% under unreliable conditions.

Implementing 6G via Non-Terrestrial Networks (NTN): Considerations for High Altitude Platform Stations (HAPS)

Implementing 6G via Non-Terrestrial Networks (NTN): Considerations for High Altitude Platform Stations (HAPS)

Fair resource optimization for cooperative non-terrestrial vehicular networks

Non-terrestrial networks aim to extend wireless communications capabilities beyond traditional terrestrial infrastructure by utilizing various platforms such as satellites, high-altitude platform stations (HAPS), and unmanned aerial vehicles to provide global or localized coverage. However, improving data rates in non-terrestrial cooperative communications (NTCC) networks presents unique challenges, necessitating innovative solutions. This paper presents a novel approach to enhance the request–response ratio (RRR) of NTCC in time asynchrony. By leveraging the advantages of HAPS, such as wide coverage, high altitude, and flexible deployment, we aim to optimize the performance of NTCC networks. We formulate an optimization problem considering the simultaneous connection between the HAPS and ground users, power distribution, and decoding order. The joint optimization problem is formulated as non-convex-non-linear and is also NP-hard, making it very challenging to obtain a globally optimal solution. To reduce the complexity of the problem and make it more tractable, we decouple it into subproblems and achieve an efficient solution in two steps. In the first step, we use the Gale–Shapley algorithm to solve the many-to-many two-sided matching problem of HAPS user terminal association, given the fixed decoding and power allocation. Then, we solve the decoding order and power allocation problem using the Dinkeback-like algorithm, given the optimal association in the second step. Our proposed method iteratively updates the preference lists, mitigating interference among HAPS and enhancing overall system performance. Through extensive simulations, we demonstrate that implementing our proposed schemes achieves high RRR compared to benchmark schemes. Additionally, when temporal asynchrony is employed alongside our approach, there is an increase in the overall performance obtained from the process.

Edge Intelligence for IoT Services in 6G Integrated Terrestrial and Non-Terrestrial Networks

Edge Intelligence for IoT Services in 6G Integrated Terrestrial and Non-Terrestrial Networks

Semantic Communication in Non-Terrestrial Networks: A Future-Ready Paradigm

Semantic Communication in Non-Terrestrial Networks: A Future-Ready Paradigm

Enhancing IoT Services in 6G Non-Terrestrial Networks With Multicast Massive MIMO

Enhancing IoT Services in 6G Non-Terrestrial Networks With Multicast Massive MIMO

Empowering 6G Non-Terrestrial Networks With Intelligent Reflection Technologies for IoT Applications

Empowering 6G Non-Terrestrial Networks With Intelligent Reflection Technologies for IoT Applications

Non-Terrestrial Networks Based on Non-Orthogonal Multiple Access Towards 6G

Non-Terrestrial Networks Based on Non-Orthogonal Multiple Access Towards 6G

Mobile networks expanding to space: Overview of the seranis beyond 5G testbed

In recent years, Non-Terrestrial Networks (NTNs) have gained increased attention from the 3rd Generation Partnership Project (3GPP) due to their potential to enhance cellular networks by improving coverage, resiliency, and reliability, especially in rural areas and disaster scenarios. The upcoming Sixth-Generation (6G) cellular networks aim to establish layers of cells at different altitudes with Base Stations (BSs) on Earth and in space, providing a seamless user experience. Testing and experimentation are crucial for realizing this ambitious vision. University of the Bundeswehr Munich (UniBw M) is deploying a Beyond 5G (B5G) and 6G testbed comprising both space and ground segments. The space segment of the testbed is composed of the ATHENE-1 satellite that is going to be launched in 2025. The ground segment includes the satellite ground station with several full motion antennas for the radiofrequency links and an optical ground station for the free-space optical link based on laser technology, while the Terrestrial Network (TN) component is deployed using a Fifth-Generation (5G) Non-Public Network (NPN) with multiple gNodeBs (gNBs) and multiple 5G core solutions. In its current state, the testbed includes various measurement equipment and emulators in the 5G Lab, a Gnb with two active cells, a core network, a satellite ground station, and a mobile 5G on-the-move solution. This testbed allows various experiments including interference management between existing networks, positioning and localization, Public Protection and Disaster Recovery (PPDR) using Multi-Access Edge Computing (MEC) and NTN. This paper describes the components of the Seamless Radio Access Networks for Internet of Space (SeRANIS) B5G testbed, the current status, future deployment plan, preliminary test results, and planned tests.

Split Learning with Differential Privacy for Integrated Terrestrial and Non-Terrestrial Networks

Integrated terrestrial and non-terrestrial networks (TNTNs) have become promising architecture for enabling ubiquitous connectivity. Smart remote sensing is one of the typical applications of TNTNs that collects and analyzes various dimensions of remote sensing data by deploying Internet of Things (IoT) sensors and edge computing in terrestrial, space, aerial, and underwater networks. To improve the analysis accuracy of remote sensing data, the owners of different networks should conduct collaborative learning on different dimensions of data, while data and label privacy should be jointly considered. However, the existing collaborative learning paradigms are difficult to meet this demand. In this article, we propose a paradigm of split learning (SL), where the data owner and the label owner train different parts of the deep learning model and only exchange the intermediate data (i.e., smashed data and cut layer gradients). We explore the potential privacy attacks that recover the raw data and label information based on the intermediate data and propose the differential privacy (DP) based defense mechanisms that inject randomly generated Laplace noise into the intermediate data to disturb the attack performance. We also conduct a simulation study based on a real-world satellite remote sensing dataset to validate that the SL paradigm with defense mechanisms can effectively balance the performance of the collaborative model training and the protection of the data and label privacy. Finally, we discuss the main challenges and potential research directions of the privacy-preserving SL paradigm for smart remote sensing over TNTNs.

Federated Cell-Free MIMO in Nonterrestrial Networks: Architectures and Performance

Federated Cell-Free MIMO in Nonterrestrial Networks: Architectures and Performance

Enhancing Resource Utilization of Non-Terrestrial Networks Using Temporal Graph-Based Deterministic Routing

Enhancing Resource Utilization of Non-Terrestrial Networks Using Temporal Graph-Based Deterministic Routing

Multi-Tier Deep Reinforcement Learning for Non-Terrestrial Networks

Multi-Tier Deep Reinforcement Learning for Non-Terrestrial Networks