Satellite Links Research Articles

Enhancing Satellite Link Security Against Drone Eavesdropping Through Cooperative Communication

ABSTRACTIntegrated satellite terrestrial networks (ISTNs) are emerging as a promising next‐generation communication technology, for example, B5G and 6G, with low‐earth orbit (LEO) satellites playing a growing role. However, the complex and unique characteristics of ISTNs make them more susceptible to cyberattacks. Recently, the use of drones for public and private services has increased the risk of eavesdropping on LEO satellite links. Such scenario presents an extremely challenging environment due to dynamic nature of LEO satellite and drone along with atmospheric attenuation at sub‐THz frequencies. This study proposes a novel adaptive power‐bandwidth cooperative scheme designed to mitigate the likelihood of eavesdropping attacks on LEO satellite links communicating with a ground station when a drone is within the line of sight. The mathematical algorithm dynamically adapts the resources to maximize the normalized secrecy capacity in this challenging scenario while maintaining a reasonable signal‐to‐noise ratio (SNR) at the legitimate receiver. The adaptive scheme involves strategic cooperation with a nearby terrestrial third party to amplify and forward the satellite signal to the ground station receiver. The simulation results demonstrate the effectiveness of the proposed algorithm, showing significant improvements (> 70%) compared to the non‐adaptive scheme over a wide range of elevation angles.

Methodological proposal for satellite communication on offshore self-elevating platform

The use of information and communication technologies has expanded the ways of working and communicating with others. However, these offer challenges when people or organizations are in places where communication is difficult. Self-elevating platforms and vessels with oil and fishing activities are in the middle of the sea, and the distance between them and the nearest port is very far. This affects the flow of information and communication that it generates to function properly. The objective of this work is to implement a satellite communication system for an offshore platform using various tools and equipment related to local area networks and satellite networks, specifically VSAT technology. The proposed and used methodology is based on experience and considers site analysis, site design, equipment installation and satellite communication tests. This has been tested in previous satellite link implementations. As a result, the parameters obtained in antenna pointing, isolation and latency tests are adequate and optimal. The applied methodology presents practical steps with specific results that can be replicated or adapted to any satellite technology implementation.

DT-DDQNR: A digital twin assisted direct-to-cell satellite network intelligent routing algorithm

This paper presents a novel routing algorithm designed for direct-to-cell satellite constellations in satellite networks. The algorithm aims to ensure stable Quality of Service (QoS) for users despite the highly dynamic nature of satellite links and network conditions. It comprises two key components: a terrestrial-satellite link selection model and an inter-satellite multi-hop routing decision model. To enhance decision-making, the algorithm incorporates a mechanism that interacts with large-scale digital twin constellations, offering agents with high-precision state data inputs and feedback for training and application support. The terrestrial-satellite link selection process is modeled as a constraint satisfaction problem, maximizing the Link Quality Indicator (LQI). Meanwhile, inter-satellite data forwarding decisions are determined utilizing an enhanced dynamic reward mechanism and a re-designed neural network in the DDQN model. Simulation results demonstrate the superiority of the Digital Twin-Assisted Double Deep Q-Network Routing (DT-DDQNR) algorithm over traditional routing algorithms in terms of overall network QoS performance, offering a promising solution for optimizing data transmission in integrated terrestrial-satellite networks.

Design and Implementation of Transparent Cross‐Polarization Interference Compensation in a Wideband Dual‐Polarization Satellite Receiver

ABSTRACTIn this paper, simultaneous transmission on two orthogonal antenna polarizations in a polarization division multiplexing (PDM) fashion is studied for wideband satellite communication links using dual‐polarization satellite receivers for the purpose of doubling the data rate. In order to mitigate the cross‐polarization interference (XPI), a new digital blind and transparent XPI compensation method is proposed, coined as XPI correlation learning estimation and adaptive reduction (XPI‐CLEAR). The received signal‐to‐noise‐and‐interference ratio (SNIR) and packet‐error rate (PER) performance with this non‐data‐aided and non‐decision‐directed method is assessed in a comprehensively modelled XPI channel with effects such as depolarization due to atmospheric conditions, imperfect cross‐polarization discrimination (XPD) of the antennas at the transmitter and the receiver, memory effects due to frequency selectivity of the XPD, and differential frequency offset (DFO) between the two channels. The application of the XPI‐CLEAR method presents considerable energy efficiency improvements for all the studied XPI channel effects, and is particularly beneficial for higher order modulation. A low‐complexity hardware implementation with symbol rates up to 500 MBaud validates the XPI‐CLEAR method as a practical solution to increase the data rates of the satellite air interface and to achieve the doubling of the throughput of the satellite link by the use of PDM.

A comprehensive systematic review of privacy and security issues in Satellite Networks

The recent advancements in satellite networks have garnered significant interest due to their extensive geographic coverage and flexible deployment capabilities, offering a promising solution for global communications and transforming traditional communication methods. Despite these advancements, current satellite systems face challenges such as high propagation delays and inadequate coverage of high-latitude regions, particularly in Geostationary (GEO) systems. Low Earth Orbit (LEO) systems, which can address these issues, are primarily used for voice services, as seen in the Iridium system, but have encountered financial difficulties. This study aims to address the security issues in satellite networks, a critical concern as these networks increasingly rely on IP protocols and hybrid configurations of terrestrial nodes and satellite links. Previous works have identified various potential security attacks on satellite networks and proposed different solutions, but these solutions often lack comprehensive effectiveness and robustness. Our methodology involves analyzing the security vulnerabilities in satellite networks similar to the Iridium system, which includes inter-satellite links (ISL) and routers on each satellite. We review and evaluate existing security measures and propose enhancements to improve their effectiveness. Our results indicate significant vulnerabilities in current systems, but also show that with targeted improvements, security can be substantially enhanced. The implications of this study are profound, suggesting that more secure satellite networks can better support critical global communications and services, including broadband Internet and data services, thereby enhancing their reliability and user trust

Impact of visibility limiting conditions on satellite and high-altitude platform quantum key distribution links.

Satellite and aerial platforms are critical in the deployment of global quantum communications networks. Currently, there remain significant challenges including operation during daytime and robustness to visibility limiting conditions. In this work we investigate, through simulation, the impact of visibility limiting conditions on low-Earth orbit CubeSat dimensioned satellites, small satellites and high-altitude platform implementations. Three different operational wavelengths were considered: currently used near-infrared (at 850 nm); next-generation short-wave infrared (at 1550 nm); and a candidate longer wavelength (at 2133 nm). We present channel attenuation and consider quantum key distribution (QKD) system performance parameters. Results indicate that the "best wavelength" for an implementation depends on the minimum visibility rated and the single-photon detector technology utilized. In the cases where tolerated meteorological visibility is short, 1550 nm and 2133 nm wavelengths provide better performance. In cases when the visibility is long, the operational wavelength of 850 nm provides better QKD system performance.

Connecting quantum cities: simulation of a satellite-based quantum network

We present and analyze an architecture for a European-scale quantum network using satellite links to connect Quantum Cities, which are metropolitan quantum networks with minimal hardware requirements for the end users. Using NetSquid, a quantum network simulation tool based on discrete events, we assess and benchmark the performance of such a network linking distant locations in Europe in terms of quantum key distribution rates, considering realistic parameters for currently available or near-term technology. Our results highlight the key parameters and the limits of current satellite quantum communication links and can be used to assist the design of future missions. We also discuss the possibility of using high-altitude balloons as an alternative to satellites.

Radiofrequency and optical satellite link budgeting calculator

Abstract Satellite communications represent one of the most widely used communication systems nowadays. From the 50’s of 20th century up to the present, the demand for satellite services has increased rapidly, so the need to design and implement reliable, up-to-date systems that meet the needs of users is increasingly imperative. Technological progress also implies a better use of the radio spectrum and the incorporation of benefits in terms of transmission performance. Traditionally, satellite systems have been implemented in the range corresponding to radio frequency, and more recently, special attention has been paid to the exploration of the spectrum corresponding to optical communications, due to the superior benefits that it offers, despite the set of challenges that its implementation represents. Such advances demand the greatest certainty of operation even from the conception and design stage of the transmission system, since satellite communications are not prone to constant changes and maintenance. The calculation process known as link budget is a tool present in the design of any wireless communications system, and its results determine the efficiency and reliability of the design. However, due to the large number of manufacturers and operators, as well as considering the novelty of using high-performance optical systems, it is difficult to stick to a single method or even to point out one as totally reliable and simple to use. With the purpose of expediting the calculation of link budgets, there are various computational tools that allow this process to be carried out. However, these tools carry the problem of poor compatibility, differences and a low degree of reliability and ease of use. In the present work, the construction and use of a web application is proposed that includes the link budget calculation process for both radio and optical satellite systems, flexible, simple, user-friendly, compatible, and mainly, abode to standardised and documented models for provide reliability and accuracy.

Two-ray channel models with doppler effects for LEO satellite communications

In this paper we present some two-ray models with Doppler effects for Low Earth Orbit (LEO) satellite links. We show that satellite motion-caused Doppler shifts are different along the two rays, resulting in a time-varying phase shift. This is quantified with a few Doppler models and approximations. The combined interference effects, along with the path length difference caused phase shift, are calculated using a generic LEO pass-over. Channel gains are computed and compared using various antenna patterns and system parameters. The models show good agreements except for very low elevation angles. They demonstrate that a tracking antenna is effective in reducing fading for moderate to high elevation angles. Fixed patch antennas perform well. Omnidirectional and dipole antennas perform poorly. Higher carrier frequency and higher antenna height lead to faster fades. The fading becomes deeper at low elevation angles. Very fast fading is observed near the ends of a pass-over.

Provably secure optimal homomorphic signcryption for satellite-based internet of things

Satellites have long been reliable and widely used mediums for communication. With recent advancements in the Internet of Things (IoT), satellite-based IoT has emerged, enhancing global connectivity by enabling real-time communication between remote sensing devices and central hubs through satellite links. However, secure and authenticated communication between Low Earth Orbit (LEO) satellites and resource-constrained ground devices remains underexplored. This paper introduces a novel homomorphic signcryption scheme designed for satellite IoT environments. Our scheme employs hyperelliptic curve cryptography and homomorphic encryption to facilitate the privacy-preserving transmission of aggregated data from multiple IoT devices to LEO satellites. We benchmark our homomorphic signcryption scheme against several established schemes tailored for different network environments, including for satellite networks, Identity-based Signcryption for Smart Grids, 3-Factor Authentication schemes and heterogeneous Vehicular Ad-hoc Networks (VANETs) encryption schemes. Our scheme demonstrates substantial improvements in computational efficiency, communication overhead, and storage capacity. It reduces computational costs by 90% to 99%, communication overhead by 41% to 92%, and storage demands by 62% to 93% compared to existing methods. These quantitative findings demonstrate the practical viability of our approach for satellite IoT deployments with limited resources. Additionally, the robustness of our approach is confirmed through formal security validation using BAN Logic and Scyther, which verifies its strong security, optimal performance, and privacy preservation capabilities, making it ideally suited for real-world satellite IoT systems.

Analysis of micro- vs. macro-flows management in QKD-secured edge computing

Quantum Key Distribution (QKD) holds the promise of a secure exchange of cryptographic material between applications that have access to the same network of QKD nodes, interconnected through fiber optic or satellite links. Worldwide several such networks are being deployed at a metropolitan level, where edge computing is already offered by the telco operators to customers as a viable alternative to both cloud and on-premise hosting of computational resources. In this paper, we investigate the implications of enabling QKD for edge-native applications from a practical perspective of resource allocation in the QKD network and the edge infrastructure. Specifically, we consider the dichotomy between aggregating all the applications on the same source–destination path vs. adopting a more flexible micro-flow approach, inspired from Software Defined Networking (SDN) concepts. Our simulation results show that there is a fundamental trade-off between the efficient use of resources and the signaling overhead, which we managed to diminish with the use of suitable hybrid solutions.

A Comparative Analysis of the Effect of Orbital Geometry and Signal Frequency on the Ionospheric Scintillations over a Low Latitude Indian Station: First Results from the 25th Solar Cycle

The equatorial post-sunset ionospheric irregularities induce rapid fluctuations in the phase and amplitude of global navigation satellite system (GNSS) signals which may lead to the loss of lock and can potentially degrade the position accuracy. This study presents a new analysis of L-band scintillation from a low latitude station at Guntur (Geographic 16.44°N, 80.62°E, dip 22.18°), India, for the period of 18 months from August 2021 to January 2023. The observations are categorized either in the medium Earth-orbiting (MEO) or geosynchronous orbiting (GSO) satellites (GSO is considered as a set of the geostationary and inclined geosynchronous satellites) for L1, L2, and L5 signals. The results show a higher occurrence of moderate (0.5 < S4 ≤ 0.8) and strong (S4 > 0.8) scintillations on different signals from the MEO compared to the GSO satellites. Statistically, the average of peak S4 values provides a higher confidence in the severity of scintillations on a given night, which is found to be in-line with the scintillation occurrences. The percentage occurrence of scintillation-affected satellites is found to be higher on L1 compared to other signals, wherein a contrasting higher percentage of affected satellites over GSO than MEO is observed. While a clear demarcation between the L2/L5 signals and L1 is found over the MEO, in the case of GSO, the CCDF over L5 is found to match mostly with the L1 signal. This could possibly originate from the space diversity gain effect known to impact the closely spaced geostationary satellite links. Another major difference of higher slopes and less scatter of S4 values corresponding to L1 versus L2/L5 from the GSO satellite is found compared to mostly non-linear highly scattered relations from the MEO. The distribution of the percentage of scintillation-affected satellites on L1 shows a close match between MEO and GSO in a total number of minutes up to ~60%. However, such a number of minutes corresponding to higher than 60% is found to be larger for GSO. Thus, the results indicate the possibility of homogeneous spatial patterns in a scintillation distribution over a low latitude site, which could originate from the closely spaced GSO links and highlight the role of the number of available satellites with the geometry of the links, being the deciding factors. This helps the ionospheric community to develop inter-GNSS (MEO and GSO) operability models for achieving highly accurate positioning solutions during adverse ionospheric weather conditions.

Hardware pipelined architecture with reconfigurable key based on the AES algorithm and hamming code for the earth observation satellite application: Sentinel-2 satellite data case

Earth Observation Satellite has facilitated the study of the earth’s environment and become powerful in various applications such as: Land temperature, Land use, urban monitoring, defense, etc. Additionally, the transmission of this image captured from the EOS to the earth must be confidential and secure against illegal access, and without data corruption. However, this task remains challenging due to the space radiation environment that could affect the satellite’s hardware, and lead to corrupted data. These issues motivate our study to provide an enhanced approach to securing the satellite and ground station link. In this paper, we propose a secure implementation-based radiation-hardened Virtex-4QV FPGA. The secure implementation utilizes a combined architecture between the AES algorithm and Hamming code to ensure security. The most significant advantage of the proposed implementation is the use of the three keys 128/192/256 bits with the pipelined architecture which leads to a high throughput and a high level of security. Based on several security criteria, the suggested cryptosystem findings demonstrate the system’s effectiveness in terms of security. Therefore, this proposed solution can be used and utilized in the EOS application.

LWARX: Lightweight ARX white-box cipher for satellite communications

Satellite communication links are vulnerable to attacks due to the lack of necessary security protection and can be considered as a white-box environment. In a white-box environment, cryptanalysts can access the intermediate processes of the algorithm and even manipulate or change the operating environment. Cryptanalysts can obtain keys or tamper with important data in many ways, which makes data communication unsecured. To solve the problem, a lightweight white-box cipher over Addition/Rotation/XOR (ARX) structure (LWARX) is proposed, which has 48 rounds of iterations through an unbalanced Feistel structure. On this basis, some of its linear operations are represented as lookup tables, and a secure external coding method is combined to complete the white-box implementation. The design and white-box implementation of the algorithm has resulted in a lighter and more rational structure, and still provides sufficient obfuscation of the data even when the S-box is discarded. The test results show that the average encryption speed is 37.53 Kbps, and average encryption speed after white-box implementation is 30.05 Kbps. And it can resist various attacks. The security of the algorithm against common attack methods such as differential analysis, linear analysis, code lifting attacks and BGE attacks is given in the paper with security analysis and specific values. This scheme balances computing efficiency and security, takes up little space, can be applied to scenarios with limited hardware and software resources, and broadens the application area of white-box cryptography.

GOCI operation during the 10 years of sun interference in COMS

A practical approach has been studied to cope with the sun interference of Earth observation geostationary satellite and the results of 10-year satellite operation for preventing sun outage are presented with detailed analysis in this paper. The Communication Ocean Meteorological Satellite (COMS) is equipped with the Geostationary Ocean Color Imager (GOCI), which performs ocean observation mission in the geostationary orbit. After the launch of the COMS, this study was initiated to prevent image data loss due to sun interference in receiving GOCI image data at the ground station of the principle user site under the operation configuration of single satellite and single ground station. This paper fully covers the entire research and the operation process which have been conducted over the 10 years from 2011 to 2021, including unexpected changes of operational environment such as ground station antenna change and satellite longitude position change. The specific characteristics of sun interference on the COMS operation is analysed through the theoretical simulation on the strength and the occurrence time of sun interference affecting the GOCI image data reception. The simulation outcomes are used to specify trigger level, date and time of sun outage in the COMS operation. From the concept that the sun outage could be prevented by adjusting the GOCI imaging time in advance, a GOCI special operation plan was established for the practical way of the sun outage prevention that was optimized for the COMS mission and could be applied to actual satellite operation. The approach of this study is verified by confirming the success of the sun outage prevention after the execution of the GOCI special operation plan. The verification is based on the operation results of the satellite link Radio Frequency (RF) signal performance and the image reception success status which has been obtained during the 10 years of the COMS operation. And, this study shows good consistency between the simulation outcomes and the operational measurements as well as the operational flexibility that it is possible to cope with the sun outage successfully even in the unexpected operational changes during the 10 years.

PEPesc: A TCP Performance Enhancing Proxy for Non-Terrestrial Networks

Non-terrestrial networks (NTNs) using flying objects such as satellites play key roles in the next-generation wireless system (6 G). The NTN links with long propagation delay and random packet losses pose a great challenge to the performance of Transport Control Protocol (TCP), which many Internet applications rely on. Performance enhancing proxy (PEP) is an easy-to-deploy approach for improving TCP's performance. In this paper, we design and implement a novel PEP called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PEPesc</i> which has two distinctive features. First, it features <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">retransmission-free</i> loss recovery, using an adaptive packet-level forward erasure correction method called streaming coding (SC). Second, as packet losses are recovered by SC, the congestion control problem is simplified to rate control and local acknowledgement between entities based on bandwidth estimation. Based on a queueing theoretic analysis of the design, we carefully devise a protocol and implement PEPesc as an open-source application. Extensive evaluations show that PEPesc can achieve much higher <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">and</i> smoother goodput than the canonical TCP variants and than other existing open-source PEPs in applications including <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">iperf</i> and HTTP-based adaptive streaming, and achieves similar performance in web browsing. Finally, we also present a deployment case over a real-world geostationary satellite link.

Real-time polarization compensation method in quantum communication based on channel Muller parameters detection

Polarization drift in fiber and free-space optical links is a major factor in the dynamic increase of bit error rate in polarization-coded quantum key distribution (QKD) systems. A dynamic polarization compensation method applicable to both links is a challenge. Here we propose a universally applicable real-time polarization compensation method, that the Muller parameters of the optical links are first detected using a polarization detector, and then the optimal parameters of the controller are obtained by gradient descent algorithm. Simulation results indicate advantages over current methods, with fewer waveplates, faster speed, and wider applicability for various optical links. In equivalent experiments of both satellite and fiber optical links, the average polarization extinction ratio of 27.9 dB and 32.2 dB are respectively achieved. The successful implementation of our method will contribute to the real-time polarization design of fiber and free-space QKD systems, while also contributing to the design of laser-based polarization systems.

Performance of the QUIC transport protocol over geostationary satellite links

Performance of the QUIC transport protocol over geostationary satellite links

AI-optimised site diversity switching for geostationary satellite links

AI-optimised site diversity switching for geostationary satellite links

A Best-Path Approach to the Design of a Hybrid Space–Ground Quantum Network with Dynamic Constraints

The design and operation of quantum networks are both decisive in the current push towards a global quantum internet. Although space-enabled quantum connectivity has already been identified as a beneficial candidate for long-range quantum channels for over two decades, the architecture of a hybrid space–ground network is still a work in progress. Here, we propose an analysis of such a network based on a best-path approach, where either fiber- or satellite-based elementary links can be concatenated to form a repeater chain. The network consisting of quantum information processing nodes, equipped with both ground and space connections, is mapped into a graph structure, where edge weights represent the achievable secret key rates, chosen as the figure of merit for the network analysis. A weight minimization algorithm allows for identifying the best path dynamically, i.e., as the weather conditions, stray light radiance, and satellite orbital position change. From the results, we conclude that satellite links will play a significant role in the future large-scale quantum internet, in particular when node distances exceed 500 km, and both a constellation of satellites—spanning 20 or more satellites—and significant advances in filtering technology are required to achieve continuous coverage.