Satellite Communication Systems Research Articles

Dynamic Resource Allocation for Multi-Beam Satellite Communication Systems

Dynamic Resource Allocation for Multi-Beam Satellite Communication Systems

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

GRU-attention Model for Linearizing Millimeter-Wave Transmitters in Vehicle to Satellite Communication Systems

GRU-attention Model for Linearizing Millimeter-Wave Transmitters in Vehicle to Satellite Communication Systems

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.

Model of operation of a high-speed satellite communication system for rational distribution of frequency-energy and time resources in the space and ground segment

Model of operation of a high-speed satellite communication system for rational distribution of frequency-energy and time resources in the space and ground segment

Random Access Control and Beam Management Scheme for the 5G NR based Beam Hopping LEO Satellite Communication Systems

Random Access Control and Beam Management Scheme for the 5G NR based Beam Hopping LEO Satellite Communication Systems

Accumulation and Elimination: A Hard Decision-Based Multi-User Interference Cancellation Method in Satellite Communication System

With the increasing number of users in the Medium-Orbit (MEO) satellite communication system, multi-access interference (MAI) has become an important factor that restricts the reliability and capacity of the system. Additionally, the low carrier-power-to-noise-density ratio (C/N0) resulting from long-distance transmission poses a significant concern. The parallel interference cancellation (PIC) algorithm, utilized within the paradigm of multi-user detection (MUD), exhibits the capability to effectively mitigate the impact of MAI within the same system. Simultaneously, coherent accumulation serves as a means to substantially enhance the correct detection probability (Pcd) at low C/N0. In this study, a signal acquisition method for multi-user spread spectrum satellite receivers is proposed, which employs interference cancellation and coherent accumulation as its core mechanisms. Furthermore, we introduce a power estimation method based on the outcomes of signal acquisition, which can be integrated into the signal reconstruction module of PIC. Finally, we implement the aforementioned algorithms in both simulation and hardware platforms. Remarkably, we observe that when the interference-to-signal ratio (ISR) caused by MAI equals 20 dB, the improved algorithm attains a maximum Pcd of 0.95 within the high signal-to-noise ratio (SNR) region, closely approaching the theoretical limit for the bit error rate (BER). The experimental results prove the effectiveness and feasibility of the acquisition algorithm. In summary, the enhanced algorithm holds vast potential for widespread implementation in multi-user spread spectrum communication systems.

Computational Tool for Rain Attenuation and Gaseous Absorption in Geostationary Satellite Links

This paper presents a computational tool for the calculation of gaseous absorption and rain attenuation in satellite communication systems with a geostationary orbit (GEO). Th software designed, planned, and implemented is based on MVC architecture that separates the code of the stages obtaining a clear and efficient structure. The software has a flow divided into three parts to process the algorithm (model, views, and controller). The software uses some forms to interact with the user and present the results of the computations in a friendly way. Additionally, to this, the program gives some files pdf to show the results and can be updated in its earth stations and satellites database.

Сравнительный анализ точности алгоритмов частотной синхронизации для системы спутниковой связи на основе сигнала DVB-S2

The paper investigates the schemes of frequency synchronization of signal reception of satellite communication system based on DVB-S2 standard with different combinations of coarse and fine frequency synchronization algorithms, namely, the following pairs of algorithms are considered: «Edge band» and «Delay & Multiply», «Delay & Multiply» and «L&R», «Edge band» and «L&R», where the first algorithm in each pair performs the task of coarse and the second algorithm performs the task of fine frequency synchronization. The accuracy of the investigated frequency synchronization schemes is evaluated using the Root Mean Square Error (RMSE) metric of frequency offset estimation in the channel. In addition, one of the performance metrics of the algorithm is the estimation of synchronization time. The frequency shift in the signal transmission channel is set constant and equal to 20% of the signal bandwidth. Using combinations of Non-Data-Aided (blind) algorithms for coarse frequency shift estimation and Data-Aided algorithms for fine frequency synchronization, the synchronization time can be reduced by almost a factor of 2, while maintaining high accuracy of RMS estimation.

Analysis of noise immunity of satellite communications under small-scale ionospheric disturbances and time-selective fading of received signals

The article develops a methodology for analyzing the noise immunity of satellite communication systems under small-scale disturbances of the ionosphere, taking into account the possibility of general and time-selective fading of received signals Differential Phase Shift Keying. The refined dependences of the intervals of time and space correlation of fading in the transionospheric radio channel on the parameters of transmitted signals and the state of the ionosphere are obtained. The analytical dependence of the probability of erroneous reception of signals with Differential Phase Shift Keying on the average signal-to-noise ratio at the receiver input, the frequency-time parameters of the signals and the characteristics of small-scale ionospheric inhomogeneities was obtained.

Towards phased array antenna operating in Ku-band for satellite communications

Satellite communication systems for mounting on vehicles are commonly based on phased array antennas with electronical beam steering. In this work we develop active metasurface-based receive-transmit antenna arrays for newly deployed satellite constellation system running in Ku-band. Both receive and transmit subarrays are based on patch-antenna elements driven in circular polarization using 90∘ hybrids. In both subarrays we optimized elements sizes and array period to have optimal ellipticity, gain, side lobe level. In electromagnetic simulations we achieved realized gain of 32.2 dBi for the Rx subarray and 33.4 dBi for the Tx subarray obtained in a broad scanning angle range from − 15∘ to + 45∘.

Reliability analysis and redundancy design of satellite communication system based on a novel Bayesian environmental importance

Satellite communication system holds a crucial role in modern society, so it is significant to improve its reliability and stability. Optimizing reliability and designing redundancy become imperative methods to ensure continuous and efficient operation of the system in the intricate space environment. In this paper, we initially model the satellite communication system using a Markov Bayesian Network in conjunction with a non-working reserve system, facilitating a systematic analysis of its reliability. Secondly, we propose a novel Bayesian environmental importance measure by considering the unique attributes of the space environment. This importance measure verifies the contributions and significance of the individual subsystems within the satellite communication system. Subsequently, we formulate a redundancy design strategy for critical subsystems to maximize reliability while minimizing costs. To solve the optimal number of redundancies of components in the subsystem, we employ the multi-objective particle swarm optimization algorithm. Finally, the effectiveness of the proposed method is demonstrated by a satellite communication system.