Satellite-based Communication Research Articles

Multi-band ultrathin reflective metasurface for linear and circular polarization conversion in Ku, K, and Ka bands

Linear polarization (LP) and circular polarization (CP) holds paramount importance in Ku, K, and Ka bands for satellite based communication, and remote sensing applications. Satellite based remote sensing applications face challenges like atmospheric attenuation, noise & interference, and signal degradation. Moreover, satellite based communication application demands CP in two distinct, non-adjacent frequency bands with orthogonal polarizations at greater oblique angles, considering the unpredictable incidence angles of electromagnetic (EM) waves. Addressing these challenges, an innovative metasurface polarization converter is proposed to operate efficiently across the Ku-band (13.5–18.0 GHz), K-band (18.0–26.5 GHz), and Ka-band (26.5–38.5 GHz) frequency ranges. The converter achieves left-handed circular polarization (LHCP) in the Ku- and Ka-bands within the frequency ranges of 14.57–15.65 GHz and 27.47–33.85 GHz for y-polarized incident EM waves. Additionally, it provides right-handed circular polarization (RHCP) in the K- and Ka-bands at 17.27–23.92 GHz and 35.87–38.32 GHz for y-polarized incident EM waves. The LP conversion ratio exceeds 95% in the frequency bands of 15.97–16.85 GHz, 24.70–26.65 GHz, and 34.37–35.45 GHz for y-polarized, LHCP, and RHCP incident EM waves, respectively. The metasurface exhibits robust performance up to incidence angles of 45 degrees under oblique conditions. Experimental validation using traditional board-circuit manufacturing demonstrates close agreement between measured co- and cross-polarized reflection coefficients and simulations in the 13.5–18 GHz, and 24–38.5 GHz frequency range. Thin metasurface with a thickness of only 0.64 = 0.013λo mm, the proposed design outperforms existing studies in the literature, establishing its competitive edge in terms of structure and performance.

LEO satellites selection-based computation offloading algorithm in aircraft–satellite multi-access edge computing networks

The emergence of sixth-generation (6G) mobile networks and non-terrestrial networks (NTNs) has led to increased interest in low Earth orbit (LEO) satellite-based communication networks for their potential to provide global coverage and ubiquitous connectivity. In this paper, we investigate the LEO satellites selection-based computation offloading problem in the aircraft–satellite multi-access edge computing (ASMEC) network, where LEO satellites and edge computing processors are integrated to provide ubiquitous and low-latency communication and computation services for aircraft during flights. In contrast to most existing works, which directly assume a fixed number of satellites or orbits in satellite-based MEC networks, we investigate the problem of how many satellites and which satellites to select in the ASMEC network. Our objective is to minimize the average total time delay of tasks during aircraft–satellite computation offloading. To achieve this, we formulate a nonlinear integer programming (NLIP) problem and propose the LEO satellites selection-based computation offloading (LSSBCO) algorithm to solve it, which includes the shortest aircraft–satellite distance based access satellite selection (ASS-SD) algorithm and the nearest k(t) neighboring satellites selection (NSS-k(t)) algorithm. We evaluate the performance of the LSSBCO algorithm in terms of the average total time delay, the maximum throughput, the average aircraft–satellite distance, the average connection duration, and the number of satellite handovers. Numerical results show that the proposed algorithm outperforms the benchmark algorithms with a lower average total time delay.

Agromet Advisories to Mitigate the Effects of Aberrant Weather in Himachal Pradesh

Weather is a pivotal factor in agricultural production, influencing crop growth, disease and pest occurrences, water and fertilizer needs, and the effectiveness of cultural and preventive measures. Extreme weather events can cause physiological stress, physical damage, soil erosion, and crop quality degradation. In India, agriculture's vulnerability to adverse weather is a significant concern, with natural disasters like floods, droughts, and cyclones leading to crop failure, food insecurity, and economic impacts. To mitigate these challenges, Agrometeorological Advisory Services (AAS) play a crucial role in providing farmers with weather-based advisories to manage agricultural risks. The Integrated Agro-Meteorological Advisory Service (IAAS), run by the Indian Ministry of Earth Sciences and the India Meteorological Department (IMD), offers district-level weather forecasts and agromet advisories to support farmers in adapting to weather fluctuations. These advisories cover various weather-related risks, including cold injury and frost, high temperatures, wind damage, hailstorms, and floods. Sample advisories suggest measures like irrigation for frost protection, mulching to reduce heat stress, and shelter belts to mitigate wind damage. Effective dissemination of advisories involves communication through electronic media, Krishi Vigyan Kendras (Agriculture Science Centres), and Kisan (Farmer) Call Centres. Thrust areas for enhancing AAS include improved scientific understanding, advanced monitoring and prediction of severe weather events, satellite-based communication technologies, and real-time forecasting. By integrating these strategies, farmers can better prepare for extreme weather and mitigate its impact on agriculture.

Miniaturized Microstrip Dual-Channel Diplexer Based on Modified Meander Line Resonators for Wireless and Computer Communication Technologies

There has been a lot of interest in microstrip diplexers lately due to their potential use in numerous wireless and computer communication technologies, including radio broadcasts, mobile phones, broadband wireless, and satellite-based communication systems. It can do this because it has a communication channel that can combine two distinct filters into one. This article presents a narrow-band microstrip diplexer that uses a stepped impedance resonator, a uniform impedance resonator, tiny square patches, and a meander line resonator. The projected diplexer might be made smaller than its initial dimensions by utilizing the winding construction. To model the microstrip diplexer topology for WiMAX and WIFI/WLAN at 1.66 GHz and 2.52 GHz, the Advanced Wave Research (AWR) solver was employed. It exhibited an insertion loss of 3.2 dB and a return loss of 16 dB for the first channel, while the insertion loss and return loss were 2.88 dB and 21 dB, respectively, for the second channel. When both filters were simulated, the band isolation was 31 dB. The projected microstrip diplexer has been fabricated using an FR4 epoxy laminate with dimensions of 32 × 26 mm2. The simulated S-parameters phase and group delay closely matched the measurements.

Machine learning approach for ionospheric scintillation prediction on ROTI parameter over the African Region during solar cycle 24

Scintillation is a dynamic phenomenon of the earth's ionosphere that adversely affects satellite-based communication and navigation systems. It is characterized by rapid fluctuations in phase and amplitude of trans-ionospheric radio waves, posing immense risks to systems that operate at radio frequencies, such as the Global Positioning System (GPS). In this regard, harnessing modern technology and state-of-the-art datasets to predict their occurrence is crucial for mitigating their effects. This paper presents a neural network approach to predict ionospheric scintillation using datasets obtained from distributed geodetic receivers in the African region. The motivation for this work is to develop a model backed by an extensive database for scintillation prediction over the region. Eleven years of data from the stations were obtained for magnetically quiet days and the Rate of TEC index (ROTI) was computed as a proxy for scintillation. The model development was backed by data from the ascending to the maximum phases of solar cycle 24 while the years in the descending phase were used for model validation and prediction. Using the solar flux (F10.7 cm), elevation and critical frequency (FoF2) as physical model parameters, the model achieved a prediction accuracy of about 70 %. A control experiment using the wavelet features increased the model's accuracy to about 91 % during the testing phase with an 86 % prediction accuracy. The model was extensively evaluated using metrics such as the Root Mean Square Error (RMSE), statistics from the Residuals and the Wavelet Coherence Analysis (WCA) technique. The standard deviation was used alongside the RMSE to gauge dispersion and ascertain model stability. The developed model demonstrated the ability to reconstruct the ROTI with low errors.

Experimental demonstration of a reconfigurable free-space receiver implementing polarization routing and filtering for daytime quantum key distribution.

Free-space quantum key distribution (QKD) systems are often designed to implement polarization-encoding protocols. Alternatively, time-bin/phase-encoding protocols are considerably more challenging to perform over a channel experiencing atmospheric turbulence. However, over the last decade, new and improved optical platforms have revived the interest in them. In this paper, we present a free-space multi-protocol receiver designed to work with three different time-bin/phase-encoding protocols highlighting its interoperability with different systems and architectures for potential satellite-based communications. We also present a detailed analysis of different experimental configurations when implementing the coherent one-way (COW) protocol in a free-space channel, as well as a polarization filtering technique showing how time-bin/phase-encoding protocols could be used for QKD applications in daylight conditions. We demonstrate secret key rates of several kbps for channels with a total 30 dB attenuation even with moderately high QBERs of ≈3.5%. Moreover, a 2.6 dB improvement in the signal to noise ratio is achieved by filtering background light in the polarization degree of freedom, a technique that could be used in daylight QKD.

Gravity-based network traffic abstraction and laser ON/OFF control in optical satellite networks

As the cost of launching low Earth orbit satellites continuously decreases, satellite-based communications networks are emerging as a new area for both academia and industry. Lasers are already employed for building inter-satellite links, forming optical satellite networks. The orbiting nature of satellites determines that the optical satellite networks are usually uniformly distributed around the Earth, to provide seamless coverage to any place at all times. However, the end users on the Earth are non-uniformly distributed. As a result, many satellites with laser links might not be utilized efficiently. From the energy perspective, this work studies the energy-efficiency issues of the inter-satellite laser links. We first model the optical satellite networks by presenting the satellite constellation with inter-satellite laser design principles and introduce the laser ON/OFF control problem accordingly. To explore the possibility of saving energy in the massive satellite deployment, we further introduce the gravity-based network traffic model and propose a gravity-based network traffic abstraction (GNTA) model to evaluate the importance of each laser link. Accordingly, we further propose a GNTA-based ON/OFF control (GOOC) algorithm to improve the energy efficiency of inter-satellite laser links by switching OFF parts of the laser links that are less utilized. We evaluate the GOOC’s performance using simulation, and results show that switching OFF 20% of the laser terminals in the full-gridmesh topology can improve the energy efficiency by about 10%, with an acceptable cost of network performance degradation.

Global ozone loss following extreme solar proton storms based on the July 2012 coronal mass ejection

Large solar coronal mass ejections pose a threat in the near-Earth space. As a cause of extreme periods of space weather, they can damage satellite-based communications and create geomagnetically induced currents in power and energy grids. Further, the solar wind energetic particles can reduce the protecting layer of atmospheric ozone and pose a threat to life on Earth. The large coronal mass ejection (CME) of July 2012, although directed away from the Earth, is often highlighted as a prime example of a potentially devastating super storm. Here we show, based on proton fluxes recorded by the instruments aboard the STEREO-A satellite, that the atmospheric response to the July 2012 event would have been comparable to those of the largest solar proton events of the satellite era. Significant impact on total ozone outside polar regions would require a much larger event, similar to those recorded in historical proxy data sets. Such an extreme event would cause long-term ozone reduction all the way to the equator and increase the size, duration, and depth of the Antarctic ozone hole. The impact would be comparable to predicted drastic and sudden ozone reduction from major volcanic eruptions, regional nuclear conflicts, or long-term stratospheric geoengineering.

Ionospheric Effect on Global Navigation Satellite System Performance - A Review

Satellite-based Communication, Navigation, Surveillance and Air Traffic Management (CNS/ATM) systems have been adopted by the international aviation community to meet the challenges of continuously rising global air traffic. Global Navigation Satellite System (GNSS) has been prescribed for the provision of navigation services to the air traffic. Performance of GNSS depends upon many factors including refraction and scintillation effects of ionosphere on the satellite signals. Severity of this effect depends largely upon the geographical location of the navigation receiver, the time of the day, the month of the year and the year on the 11-year solar cycle. This paper studies ionosphere mechanism and discusses its effect on the performance of GNSS. The paper also predicts the performance during solar cycle maximum expected in 2013-2014 [Jensen, Anna B.O., Mitchell, Cathryn 2011]. It touches upon the preparations going on to face the adverse effects of increased solar activity during the cycle maximum and recommends coordination/cooperation between various relevant organizations/institutions in the processes of data collection and development of a model.

Generation of equatorial plasma bubble after the 2022 Tonga volcanic eruption

Equatorial plasma bubbles are a phenomenon of plasma density depletion with small-scale density irregularities, normally observed in the equatorial ionosphere. This phenomenon, which impacts satellite-based communications, was observed in the Asia-Pacific region after the largest-on-record January 15, 2022 eruption of the Tonga volcano. We used satellite and ground-based ionospheric observations to demonstrate that an air pressure wave triggered by the Tonga volcanic eruption could cause the emergence of an equatorial plasma bubble. The most prominent observation result shows a sudden increase of electron density and height of the ionosphere several ten minutes to hours before the initial arrival of the air pressure wave in the lower atmosphere. The propagation speed of ionospheric electron density variations was ~ 480–540 m/s, whose speed was higher than that of a Lamb wave (~315 m/s) in the troposphere. The electron density variations started larger in the Northern Hemisphere than in the Southern Hemisphere. The fast response of the ionosphere could be caused by an instantaneous transmission of the electric field to the magnetic conjugate ionosphere along the magnetic field lines. After the ionospheric perturbations, electron density depletion appeared in the equatorial and low-latitude ionosphere and extended at least up to ±25° in geomagnetic latitude.

Machine Learning-Based Solutions for Handover Decisions in Non-Terrestrial Networks

The non-terrestrial network (NTN) is a network that uses radio frequency (RF) resources mounted on satellites and includes satellite-based communications networks, high altitude platform systems (HAPS), and air-to-ground networks. The fifth generation (5G) and NTN may be crucial in utilizing communication infrastructure to provide 5G services in the future, anytime and anywhere. Based on the outcome of the Rel-16 study, the 3rd generation partnership project (3GPP) decided to start a work item on an NTN in 5G new radio (NR) Rel-17, and the focus of the study was on mobility management procedures, due to the movements of NTN platforms; especially, low earth orbit (LEO) satellites. Handover enhancements were discussed to tackle the frequent handover due to the fast satellite movement. Therefore, the major problem of handover in LEO satellite systems was the signaling storm created by handing over all user equipment (UE) in a cell to a new cell because when the UE crosses the boundary between the neighboring cell of a satellite, an intra-satellite or cell handover occurs; thus, all users in a cell are expected to experience a change of cell due to handover every few seconds. In addition, UE location is not easy to define due to moving cell/beam situations. In this study, we propose machine learning-based solutions for handover decisions in non-terrestrial networks for cell handovers or intra-satellite handovers to reduce signaling storms during handovers where the handover requests will be executed by clustered users. First, the dataset was generated by the simulator that simulates communication between users and satellites. Second, we preprocessed the data, and also used the feature creation technique to create the distance feature using the Haversine formula, and then applied clustering and classification algorithms. The experimental results show that the distance between a user and its cell center is an important parameter for handover decisions in NTN, and the random forest outperforms all models with a higher accuracy of 99% along with a better F1-score of 0.9961.

Terabit FSO communication based on a soliton microcomb

Free-space optical (FSO) communication technology is a promising approach to establish a secure wireless link, which has the advantages of excellent directionality, large bandwidth, multiple services, low mass and less power requirements, and easy and fast deployments. Increasing the communication capacity is the perennial goal in both scientific and engineer communities. In this paper, we experimentally demonstrate a Tbit/s parallel FSO communication system using a soliton microcomb as a multiple wavelength laser source. Two communication terminals are installed in two buildings with a straight-line distance of ∼ 1 km . 102 comb lines are modulated by 10 Gbit/s differential phase-shift keying signals and demodulated using a delay-line interferometer. When the transmitted optical power is amplified to 19.8 dBm, 42 optical channels have optical signal-to-noise ratios higher than 27 dB and bit error rates less than 1 × 10 − 9 . Our experiment shows the feasibility of a wavelength-division multiplexing FSO communication system which suits the ultra-high-speed wireless transmission application scenarios in future satellite-based communications, disaster recovery, defense, last mile problems in networks and remote sensing, and so on.

Equatorial Plasma Bubbles: A Review

The equatorial plasma bubble (EPB) phenomenon is an important component of space weather as the ionospheric irregularities that develop within EPBs can have major detrimental effects on the operation of satellite-based communication and navigation systems. Although the name suggests that EPBs occur in the equatorial ionosphere, the nature of the plasma instability that gives rise to EPBs is such that the bubbles may extend over a large part of the global ionosphere between geomagnetic latitudes of approximately ±15°. The scientific challenge continues to be to understand the day-to-day variability in the occurrence and characteristics of EPBs, such as their latitudinal extent and the development of irregularities within EPBs. In this paper, basic theoretical aspects of the plasma processes involved in the generation of EPBs, associated ionospheric irregularities, and observations of their characteristics using different techniques will be reviewed. Special focus will be given to observations of scintillations produced by the scattering of VHF and higher frequency radio waves while they propagate through ionospheric irregularities associated with EPBs, as these observations have revealed new information about the non-linear development of Rayleigh–Taylor instability in equatorial ionospheric plasma, which is the genesis of EPBs.

Satellite-based communications security: A survey of threats, solutions, and research challenges

Satellite-based Communication systems are gaining renewed momentum in Industry and Academia, thanks to innovative services introduced by leading tech companies and the promising impact they can deliver towards the global connectivity objective tackled by early 6G initiatives. On the one hand, the emergence of new manufacturing processes and radio technologies promises to reduce service costs while guaranteeing outstanding communication latency, available bandwidth, flexibility, and coverage range. On the other hand, cybersecurity techniques and solutions applied in SATCOM links should be updated to reflect the substantial advancements in attacker capabilities characterizing the last two decades. However, business urgency and opportunities are leading operators towards challenging system trade-offs, resulting in an increased attack surface and a general relaxation of the available security services. In this paper, we tackle the cited problems and present a comprehensive survey on the link-layer security threats, solutions, and challenges faced when deploying and operating SATCOM systems.Specifically, we classify the literature on security for SATCOM systems into two main branches, i.e., physical-layer security and cryptography schemes.Then, we further identify specific research domains for each of the identified branches, focusing on dedicated security issues, including, e.g., physical-layer confidentiality, anti-jamming schemes, anti-spoofing strategies, and quantum-based key distribution schemes. For each of the above domains, we highlight the most essential techniques, peculiarities, advantages, disadvantages, lessons learned, and future directions.Finally, we also identify emerging research topics whose additional investigation by Academia and Industry could further attract researchers and investors, ultimately unleashing the full potential behind ubiquitous satellite communications.

A Way to Access SCADA System via Satellite Channel and its relevant Security Trends

SCADA systems have been playing important roles for industrial automation and processing, as the results the productions can be produced in minimal time with more efficiency and profitability. Mainly, the whole industrial production is carried through various connected sensors or field devices, which may configured in local area network (LAN)/Wide area network (WAN). In previous two decades, wireless based communication gained popularity and the SCADA industries (such as oil, gas and water) also accepted and deployed their production through the use of wireless media. To be more advanced, the SCADA systems are also required to access the remote networked devices that may located at various places in the World over wireless links, thus the best solution is satellite communication. Satellite transmission will provide an easy, faster and efficient access to, monitor and control the geographical networked remote devices from the central location or central station, which also a main goal of this study. This study proposes a satellite based communication facility for SCADA water station, moreover security issues that mainly linked with satellite transmission are also considered and relevant protection mechanisms are suggested.

Quantum steering with vector vortex photon states with the detection loophole closed

Violating a nonlocality inequality enables the most powerful remote quantum information tasks and fundamental tests of quantum physics. Loophole-free photonic verification of nonlocality has been achieved with polarization-entangled photon pairs, but not with states entangled in other degrees of freedom. Here we demonstrate completion of the quantum steering nonlocality task, with the detection loophole closed, when entanglement is distributed by transmitting a photon in an optical vector vortex state, formed by optical orbital angular momentum (OAM) and polarization. As well as opening up a high-efficiency encoding beyond polarization, the critically important demonstration of vector vortex steering opens the door to new free-space and satellite-based secure quantum communication devices and device-independent protocols.

A Survey on Authentication in Satellite Internet

Satellite Internet is a promising technology that provides global connectivity and has attracted widespread attention from both industry and academia. However, the open nature of wireless communication links renders Satellite Internet vulnerable to signal spoofing and illegal access attacks. Authentication has been recognized as an effective countermeasure to these attacks. Therefore, this paper presents a comprehensive survey of existing authentication schemes in Satellite Internet for the first time. We categorize existing authentication schemes into two main scenarios, i.e., the Satellite-based Communication (SATCOM) system and the Global Navigation Satellite System (GNSS) scenario. We further divide the literature in the SATCOM scenario into five sub-categories and that in the GNSS scenario into two sub-categories. Finally, we discuss the challenges that existing authentication schemes are facing and will face and further present some future research directions.

Space for the Sustainable Development Goals: mapping the contributions of space-based projects and technologies to the achievement of the 2030 Agenda for Sustainable Development

Progress towards the achievement of the 17 Sustainable Development Goals (SDGs) of the 2030 Agenda for Sustainable Development in many ways presupposes the utilisation of science, technology and innovation. Many sustainability-oriented projects across industries make use of space-based technologies and services to contribute to the Goals. Among others, satellite-based Earth observation, positioning, navigation and communication services are used in an array of sectors ranging from monitoring environmental conditions and changes to supporting search and rescue missions. In order to illustrate contributions to the SDGs, space agencies and other institutions have aligned their projects to the SDG framework. This study attempts a more holistic, aggregate mapping of such alignments to gauge which SDGs benefit the most and from space-based projects and technologies, as opposed to those benefiting the least. The results demonstrate that the number of contributing projects varies significantly across the Goal spectrum, as does the share of the various technologies involved, with particular focus on industrial development, hunger elimination, and improved healthcare. Nevertheless, the range of application of space-based technologies is wide and highlights the relevance of space to support the transition towards a sustainable future.

Help from space: grant-free massive access for satellite-based IoT in the 6G era

The Sixth-Generation (6G) standard for wireless communications is expected to realize ubiquitous coverage for massive Internet of Things (IoT) networks by 2030. Satellite-based communications are recognized as a highly promising technical enabler to satisfy IoT service requirements in the 6G era. This study analyzes multiple access technologies, which are essential for the effective deployment of satellite-based IoT. First, we thoroughly investigate the existing research related to massive access, including information-theory considerations as well as Non-Orthogonal Multiple Access (NOMA) and Random Access (RA) technologies.Then, we explore the influence of the satellite transmission environment on multiple access technologies. Based on this study, a Non-orthogonal Massive Grant-Free Access (NoMaGFA) scheme, which reaps the joint benefits of RA and NOMA, is proposed for asynchronous transmissions in satellite-based IoT to achieve improved system throughput and enhance the system robustness under varying traffics. Finally, we identify some important and interesting future developments for satellite-based IoT, including waveform design, transceiver design, resource allocation, and artificial intelligence-enhanced design.

Study of different performance measures and their relations in satellite‐based and terrestrial quantum communication

Rapid developments in quantum communication are paving the way forward for more advanced technologies. Conventional channels like optical fibres have been a great resource in recent decades. However, they suffer largely from exponential transmissivity decays and are not suitable for very long-distance communication. Satellite links along with quantum cryptography can be the foundation of modern quantum communication systems. This work presents an overview of the hybrid quantum repeater with a detailed analysis of different parametric relations in satellite-based communication from experimental data. The link efficiency between the satellite-based scheme and terrestrial scheme is also compared, emphasising the satellite-based scheme's importance for quantum communication. Finally, we present a performance analysis of different quantities and derive relations between them.