Satellite Communication Systems Research Articles

Investigation of mutual coupling coefficients in dual-polarized antenna arrays

Background. Antenna arrays are widely used in various fields of radio engineering, such as radio and telecommunications, satellite communication systems, etc. One of the important characteristics of an antenna array is its radiation pattern. The estimation of impedance matrices, scattering matrices, and partial radiation patterns is usually performed based on the results of numerical electrodynamic modelling. In the case of a large number of antenna elements, such modelling and optimization of the array requires significant time.
 Aim. To investigate the mutual coupling between dual- polarised antenna elements included in a linear antenna array.
 Methods. Modelling of antenna arrays based on cross-dipole elements was performed using methods of electrodynamic modelling software. The study of the mutual coupling of antenna elements in the antenna array and verification of the developed mathematical model were carried out by numerical methods.
 Results. A physical interpretation of that there is no almost interaction between the elements operating in orthogonal polarizations, and the coefficients of mutual coupling decrease with increasing distance between antenna elements is given. Proposed a simplified model of mutual coupling, which reduces the computational complexity of the problem of determining the mutual coupling matrices.
 Conclusion. It is developed a mathematical technique that allows to calculate the characteristics of antenna arrays with a large number of antenna elements, meanwhile electrodynamic modelling is carried out only for an isolated antenna element and a two-element array.

Design of Energy Efficient Multi-HAPS Assisted Hybrid RF/FSO Satellite Communication Systems With Optimal Placement

Design of Energy Efficient Multi-HAPS Assisted Hybrid RF/FSO Satellite Communication Systems With Optimal Placement

Problems of implementation of integrated satellite-ground NTN-network

The article is devoted to the discussion of challenges that arise during the rapid technological progress in satellite communication systems. The paper proposes an integrated satellite-ground system for systems of the 5G generation and above, discusses its architecture, methods and problems of its implementation, and scenarios for the use of the described system. Application areas requiring the depicted integrated architecture are described, and how this flexible multi-technology system can be used to provide global coverage and reliable access, provide transport communication via a satellite link, and data processing and content caching at the mobile edge. A multi-level network architecture with satellite and terrestrial elements will allow to create a telecommunications network with minimal delay, high deployment speed, guaranteed high quality of service and dynamic scalability, which can be controlled depending on the degree of system load and user needs in real time. Among the necessary technological solutions required for the successful implementation of the proposed system in the implementation of 5G are the following: millimeter-band communication, multi-access edge computing, network management and sharing, and spectrum sharing solutions.

Quantum Annealing for Complex Optimization in Satellite Communication Systems

Quantum Annealing for Complex Optimization in Satellite Communication Systems

A Stackelberg Differential Game Framework for Enhancing Energy Efficiency in Satellite Communication Systems

A Stackelberg Differential Game Framework for Enhancing Energy Efficiency in Satellite Communication Systems

6G Vision, IoT Technologies, Challenges and Emerging Technology Solutions—A Survey

The fifth generation (5G) is yet to be implemented globally, researchers have been impelled to envision 6G to provide evolving services and applications with high-class execution. The sixth-generation network technology is expected to support huge number of Internet of Things (IoT) devices needed to sustain higher data rates applications. Compared to the IoT provisions deployed in 5G, 6G IoT uses high density diverse gadgets with huge bandwidth, robust architecture and smart algorithms built on artificial intelligence (AI). It will enable novel applications with the help of AI and big data technologies. The existing 6GHz band is at present packed by data traffic. The lower transmission band cannot withstand higher data traffic transmission. Communication technology based on the Millimeter Wave (mmWave) is capable of supporting higher data rate transmission but at the cost of consuming high power and high hardware cost, thus violating the low-cost design norm of IoT devices. In this paper, we aim to provide 6G vision of IoT, the Key technologies and challenges involved. Various approaches such as Radio over Fiber technologies, wireless beam modulation (WBM) technique for transmitting mmWave, Satellite communication system is anticipated to perform a major role in IoT and applications in 6G vision and green communication for super performance in terms of energy efficiency are addressed to meet the high requirements of a 6G IoT system. Techniques such as convergence of 6G IoT with RoF will provide benefits of both wireless and optical technology, generating more challenges and prospects in the future. A comprehensive survey of current developments in 5G and 6G and future trends is presented in this survey article.

A synergetic approach to the development of the economic potential of the aviation complex enterprises

The potential of aviation enterprises makes it possible to increase the volume of development and production of aviation equipment, in particular: regional passenger and transport aircraft; aircraft engines and units; on-board radio-electronic equipment aimed at the use of satellite communication, navigation and observation systems; helicopters and general aviation aircraft, including unmanned ones; military goods and dual-use products. It is substantiated that the harmonization of the modern system of state regulation of the integration of the foreign trade sector of Ukraine into the EU should be carried out based on the fact that the parties have excellent reasons for forming an integration association. The consistent implementation of worldview and methodological procedures for maximizing the use of potential is, first of all, a tool for overcoming the low level of economic development, efforts through unification to create better conditions for the industrialization and development of aviation enterprises, the possibility of qualitative transformation of the foreign trade sector by attracting foreign investments and high technologies. This approach should contribute to the fundamental restructuring and diversification of export supplies, increase the opportunities to use positive development trends, and increase the level of international competitiveness of domestic economic entities. The results of the diagnostics of aviation enterprises made it possible to reveal the expediency of forming a new structure of interaction of enterprises and systematizing them into an aviation complex, which is considered as a set of organizations involved in the development, testing, production, sale, operation, modernization and repair of aviation equipment, which form several interconnected clusters.

Frequency Resource Allocation Using Combined Evaluation Function in High Throughput Satellite Communication System

Frequency Resource Allocation Using Combined Evaluation Function in High Throughput Satellite Communication System

Channel correlation based user grouping algorithm for nonlinear precoding satellite communication system

Channel correlation based user grouping algorithm for nonlinear precoding satellite communication system

Reduced-Complexity Decoding of 3D Product Codes for Satellite Communications

This paper aims to provide a reduced-complexity decoding for satellite communication systems to enhance system performance and transmission efficiency. By addressing the complexity, error rate, and latency issues for satellite communications, a novel 3-dimensional product decoding scheme is proposed. The density evolution algorithm is also introduced to analyze and optimize for the binary message passing decoding, which further reduces the computational complexity and latency. The simulation results show that the proposed method can obtain about 0.3- and 0.15-dB performance gains compared to the similar decodings of the conventional 2-dimensional BCH product codes and staircase codes, respectively. Our proposed coding scheme offers a broad prospect to the critical issues of transmission latency and data throughput in satellite networks.

Dynamic Beam Hopping and Resource Allocation for Non-Uniform Traffic Demand in NGSO Satellite Communication Systems

Dynamic Beam Hopping and Resource Allocation for Non-Uniform Traffic Demand in NGSO Satellite Communication Systems

All-optical suppression on the impact of Sun outage in laser satellite communication systems by using a nonlinear semiconductor optical amplifier

All-optical suppression on the impact of Sun outage in laser satellite communication systems by using a nonlinear semiconductor optical amplifier

Electronic Judicial Procedure as an Element of Access to Justice Regarding Protection of Rights of Individuals: Legal, administrative, Theoretical and Informational Aspects

The purpose of the research is to consider electronic judicial procedure as an element of access to justice regarding protection of rights of individuals. Main content. It has been established that that certain elements of digitalization of social processes change the social space and, in particular, the mechanisms of judicial proceedings. In the process of the development of society, certain factors came to life and these factors led to the growth of the role of information, and therefore to a clearer allocation of the information function in the field of jurisprudence. Development of society and science requires introduction of new technologies into the judicial system of Ukraine. Methodology: The methodological basis of the research is presented as comparative-legal and systematic analysis, formal-legal method, interpretation method, hermeneutic method as well as methods of analysis and synthesis. Conclusions. The following conclusion was made that the need to use information technologies in the judiciary is due to the global informatization of the modern society, the development of new forms of interaction in the civil sphere with the use of electronic means of communication: the global Internet, mobile and satellite communication systems, etc. “Electronic justice” involves the use of information and communication technologies in the process of implementing procedural legislation. The novelties of the judicial system are aimed at expanding accessibility of justice in conditions of territorial peculiarities of the Ukrainian state, improving the quality of the process and efficiency, achieving transparency and openness of the judicial system.Key words: electronic judicial procedure, access, justice, protection, rights of individuals.

Ensuring Legal Safeguards for Digitalized Social Services within the Framework of Government Decentralization

The purpose of the study is to digitize the social services system in the context of decentralization of power: legal regulation and areas of improvement. Main content. It has been established that new online services are being introduced in Ukraine to enable consumers to receive such services virtually. In our opinion, in the future, these services should simplify the procedure for access to them, taking into account the entities which are primarily interested in using them, and expand the scope of their provision: from informing the consumer to obtaining the result. The society and science development requires the introduction of new technologies into the service system. It has been concluded that the need to use information technologies in judicial proceedings is due to the global informational support of modern society, and development of new interaction forms in the social area using electronic means of communication: the global Internet, mobile and satellite communication systems. The author reveals the essence of "Portal Diia", which is introduced within the framework of the Unified Social Information System of a single electronic document in the social matters, and highlighted the disadvantage of this application: ensuring the protection of personal data, and access to information about the citizen sphere of interests accumulated in computer networks.

From the History of the Development of Russian Space Television

The article examines the activities for the development of the space television system in Russia. The date of birth of the national space television is October 7, 1959. It is the day of the beginning of the radio and television transmission of images of the far side of the Moon to Earth. In 1971, the international satellite communication and broadcasting system Intersputnik was created in the USSR. Soon after the beginning of its development, the control of the Earth from space for the purposes of space surveillance and aerospace defense became an important function of space television.

Electromagnetic Accessibility of Starlink User Terminals

The results of assessing the electromagnetic accessibility of radio emission sources of the Starlink satellite communication system are presented. The features of the organizational and technical structure of the system are considered. Its main technical capabilities for organizing the provision of telecommunications services to users of subscriber terminals are analyzed. The technical features of the infrastructure of the Starlink satellite communication system, which are essential for the electromagnetic accessibility of its sources, have been studied. The possibility of radio links for transmitting information content in the upstream and downstream channels of the Starlink satellite communication system was assessed. The main stages of the developed methodology for assessing the electromagnetic accessibility of sources are presented. Analytical expressions are given for calculating the probability of detection and attenuation of signals. The requirements for the sensitivity of the receiving equipment of monitoring equipment are substantiated. Dependences of the level of signal attenuation on the distance of control equipment were obtained.

Novel T-Shaped Gate Structure of AlGaN/GaN HEMTs on Si for RF Application

Due to the high electron saturation velocity and breakdown electric field, GaN-based high electron mobility transistors (HEMTs) have been widely used in high frequency and power application, such as telecommunication, satellite communication, and radar system [1]. Since first demonstration of AlGaN/GaN HEMTs in 1993 [2], the RF performance of these device has continuously improved by the progress on epitaxy and device scaling technology [3].The current gain cut-off frequency (fT) and the maximum oscillation frequency (fmax) from the small-signal equivalent circuit of the HEMT are derived by the following equations [4].From these equations, it can be concluded that in order to achieve high frequency operation, HEMTs should be designed with a T-shaped gate structure that simultaneously achieves low gate resistance (Rg) and low parasitic capacitance (Cgs and Cgd). However, there are complex fabrication processes to form the T-shaped gate. Typically, the T-shaped gate structure is implemented through electron beam lithography process using a tri-layer resist such as PMMA/PMGI/PMMA, which requires multiple exposures or developments. Multiple exposures can cause overlay errors that can significantly affect the T-shaped gate with smaller gate lengths [5]. Also, it is difficult to obtain an undercut structure that enables a good lift-off and guarantees a high yield due to the need for precise dose control. In addition, since the T-shaped gate has an unstable structure in which a narrow foot supports the weight of a wide head, the gate may collapse during a subsequent process.In this work, we fabricated a novel T-shaped gate using the negative e-beam resist HSQ, which offers a simple T-shaped gate fabrication process. The HSQ that was exposed to e-beam is located underneath the gate head and on both sides of the gate foot in our novel T-shaped gate design, providing a robust structure. The HSQ-assisted gate HEMTs exhibit comparable DC/RF performance compared to conventional T-shaped gate HEMTs. Acknowledgement This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MIST) (No. NRF-2021M3C13097672).

Photonic generation and transmission for an X-band dual-chirp waveform with frequency multiplication and power-fading compensation.

The generation of an X-band dual-chirp waveform, which is capable of pulse compression, plays an important role in radar, electric warfare, and satellite communication systems. With the development of applications such as multi-static radar, transmission over long distances has attracted considerable attention. In this paper, a photonic system for X-band dual-chirp waveform generation and transmission based on frequency multiplication and power-fading compensation is put forward and experimentally carried out. Based on a compact dual-parallel Mach-Zehnder modulator (DPMZM), the dual-chirp waveforms of 8.6-9.6GHz and 9.6-10.6GHz are generated by an RF carrier of 4.8GHz and transmitted through a 40km single-mode fiber (SMF) spool. The dispersion-induced power fading of the chirp waveform is compensated for by about 13dB. The full width at half maximum (FWHM) and the peak-to-sidelobe ratio (PSR) of the compressed pulses are 1ns and 11.5dB, respectively. Moreover, the compensation of power fading in the entire X-band is verified to demonstrate the applicability of our system. By flexibly adjusting the bias voltage of the built-in phase shifter, the system can be applied in more scenarios.

A NavCom Signal Authentication Scheme Based on Twice Two-Way Satellite Time Transfer

Low Earth Orbit (LEO) satellite communication systems typically achieve identity authentication through the encryption and decryption of two-way information, which requires complex key management systems. In contrast, the integration of navigation and communication (NavCom) signals provides novel opportunities for physical observation and authentication solutions due to its measurement functions. This paper introduces a novel signal authentication scheme based on twice two-way satellite time transfer (TWSTT) for LEO satellite systems. It leverages the non-mutated nature of the clock difference to ascertain the legitimacy of the signal by measuring the clock difference of signals at different instances. Unlike traditional authentication methods, this approach directly exploits the temporal and spatial characteristics of the signal, negating the necessity for intricate authorization key systems. Additionally, it adeptly tackles the challenges posed by spoofing interference. The performance analysis indicates that this scheme can achieve a high detection probability for the repeater spoofing signal in the low carrier-to-noise ratio conditions.

Development of a Numerical Simulation Model to Support the Design of a Ship–Satellite Communication System for Autonomous Marine Navigation

In recent years, the concept of autonomous navigation systems has gained substantial significance, with the potential to change the traditional concept of autonomous navigation. The presented numerical simulation investigates the feasibility of a ship’s autonomous navigation system through a laser communication infrastructure handled by a two-degrees-of-freedom (DoFs) acquisition, tracking and pointing (ATP) system able to enable ship–satellite data transmission. The methodology introduced presents the geometrical and kinematic delineation of the model, coupled with the implemented control system, aimed at assessing the pointing accuracy. The minimum requested pointing accuracy is 100 µrad and the analysis highlights the need of using methodologies to reduce the pointing error. Two approaches are investigated to examine a possible improvement of the system, and results show that the pointing phase is influenced less by ship motions and more by errors that occur during the satellite’s positioning and the ship motion acquisition process. A trade-off in choosing parameters to improve the system’s accuracy leads to a satellite’s first targeting time of 0.25 s alongside the probability of hitting the target once every 0.0013 s. The reliability of the system is evaluated through a brief sizing of the optical electromechanical component of the system using the trade-off parameters chosen to improve the pointing phase accuracy.