Earth Station Research Articles

Sudanese Communications GEO Satellite: A case study on SUDASAT

Recently, and to cater to increased needs for communicating through satellite, there has been a growing interest in the marketplace as well as in the research community to develop advanced applications utilizing satellite communications systems. Satellite communications are becoming a common trend in Arab countries. A growing body of literature has focused on developing Geostationary Satellite (GEO) satellites. However, International Telecommunications Union (ITU) have the main coordination for all GEO satellite around the world. The present paper seeks to address the main timelines which relate to a Sudanese satellite. This research study is focused on GEO SUDASAT to offer a variety of communications applications in Sudan. The obtained data is provided from Space Capture ITU software. In this paper, we investigate a proposal for a Sudanese satellite called SUDASAT. The main goal of this paper is to define the SUDASAT technical information which consists of satellite orbital position, the main earth station, and its look angles, the coverage area, launch vehicle, satellite manufacturer and the suitable platform, EIRP, G/T, frequency bands, and several transponders.

Adaptive Access Selection Algorithm for Large-Scale Satellite Networks Based on Dynamic Domain.

The traditional satellite access selection algorithm, which is used in large-scale satellite networks, has some disadvantages, such as frequent link switching, high interrupt probability, and unable to adapt to a dynamic environment. According to the periodicity of the large-scale satellite network and the prior knowledge provided by acknowledgment packages, a dynamic domain-based adaptive access algorithm (DAA) is proposed in this paper. Firstly, this algorithm divides the large-scale satellite network into different domains according to the minimum elevation angle of the Earth station (ES) and the predictable characteristics of the trajectory of the satellite. Then, the ES selects the access satellites according to the relationship between the traffic volume and the satellites’ coverage time. Finally, the ES selects the backup access satellite based on the satellites’ coverage time, the traffic volume of the ES, satellite status provided by prior knowledge, and other information. When the access satellite cannot satisfy the communication demand, the ES adaptively switches the earth-satellite link to the backup access satellite. The ES first choice of access satellite does not require interaction with the satellites, reducing the consumption of communication resources. The selection strategy of backup access satellite and the concept of virtual destination address proposed in this paper can reduce the routing overhead after switching. Through theoretical analysis and simulation results in the StarLink constellation, it is proved that this paper improves the coverage time utilization of accessing satellites and reduces the switching probability compared with the traditional access algorithm, which is more suitable for ES to access large-scale satellite networks.

Device to Monitor Radio Path Operation of Earth Station of Satellite System for Remote Sensing of the Earth

Device to Monitor Radio Path Operation of Earth Station of Satellite System for Remote Sensing of the Earth

Compact Dual Bandpass Filter Using Dual-Split Ring Resonator for 5G Upper Microwave Flexible Use Services

A novel, compact dual bandpass filter design is proposed for 5G upper microwave flexible use services. To realize the proposed design, a dual split-ring resonator structure coupled to the microstrip transmission line is used. The output responses have been validated using vector network analyzer N5222A. The measured filter records a frequency range of 23.8 GHz–25.98 GHz for the first passband and 28.05 GHz–28.7 GHz for the second band, with fractional bandwidths of 8.8% and 2.2%, respectively. The minimum insertion loss is observed to be 4.2 dB using microstrip technology, even at higher frequencies. The proposed design occupies the area of 0.4 λg×0.27 λg, where λg is guided wavelength at the lower band central frequency. Simulated and measured results are approximately compatible with each other. The proposed design is useful for fixed satellite service earth stations, terrestrial wireless operations, and 5G mobile communications applications.

Evaluation of 5G Coexistence and Interference Signals in the C-Band Satellite Earth Station

Fixed Satellite Services (FSS) used to be alone at the C-Band spectrum in most countries. Since the deployment of 5G in many countries (i.e., 3.3–3.6 GHz), FSS is not the exclusive system in the C-Band anymore. In order to minimize the detrimental interference for the FSS to allowable levels, regional exclusion zones of maximum radiated power in 5G base stations (BS) are proposed and evaluated. In this paper, a measurement campaign has been carried out, and an analysis of the interference has been studied. A filtering model, namely Filter to Remove Broadband Interference 5G (FIREBRING), is proposed and analyzed concerning the carrier-to-noise ratio (C/N). Moreover, this paper focuses on the evaluation of the 5G interference into the FSS. The proposed solution deployed an Low-Noise Block (LNB) with a band frequency of 3.7 to 4.2 GHz to test the satellite down-conversion signal at the receiver. The paper offered a complete analysis of the 5G signal, taking into account the implications of out-of-band emissions, potentially LNB saturation into FSS receiver, and the repercussions of the deployment of the 5G BS active antenna systems. With the LNB and down-converter in place, it can be found that the signal interference between 1.450 GHz and 1.550 GHz, is nearly 18 dB.

Performance Analysis of Power Budget Management for Satellite Design under Ka Band Frequency Band

Abstract: In the manuscript, a power budget analysis is performed for the estimation of the link budget between satellite and ground station. Various parameters have been considered for this estimation that includes aperture efficiency, operating wavelength, earth station antenna diameter. Several calculations have been performed for the assessment of link budget related to the transmitted power with respect to various carrier-to-noise (C/N) ratio. Keywords: C/N, Aperture, Ka, VSAT

4-degrees of freedom attitude equations of motion: A new approach for simulating flexible satellite dynamics with time-varying payload despite time delay and disturbances

A new approach for the pointing of satellite’s payload is improving the dynamics of satellites to more than 3-DOF. In this approach, there would be no requirement for satellite complete rotations to perform the payload’s mission. The purpose of this study is to derive Four Degrees of Freedom (4-DOF) equations of motion of a satellite and its payload. Therefore, the payload can observe an area of the earth, and simultaneously, the satellite can transfer data to the earth station. Lagrange dynamics are utilized to derive 4-DOF dynamic equations of the system. Then, the system of payload-satellite is controlled by the sliding mode control method with three different sliding functions. Environmental disturbances and appropriate time delay for Low Earth Orbit are applied to the nonlinear attitude equations. Numerical simulations demonstrate the effectiveness of the 4-DOF nonlinear dynamics of the payload-satellite system and indicate that the controller negates the effects of the nonlinear external disturbances and time delay. According to the results, the attitude states attain the reference targets of Euler angles and the time-varying payload with excellent precision and high convergence speed.

Mixed FSO/RF Based Multiple HAPs Assisted Multiuser Multiantenna Terrestrial Communication

In this work, a mixed free-space optics (FSO)/radio-frequency (RF) based multiple serial high altitude platforms (HAPs) assisted multiuser multiantenna terrestrial communication system is considered. For the considered multi-hop system, earth station to HAP and HAP to HAP links are assumed as FSO links, and HAP to terrestrial mobile users (MUs) link is assumed as RF link. At the FSO detector both the heterodyne detection and intensity modulation direct detection techniques are considered. Atmospheric turbulence of the ES to HAP FSO link is modeled with Gamma-Gamma fading along with the pointing error impairments. As HAP situates in the stratosphere, negligible atmospheric turbulence exists at HAP altitude (20 km), hence, only pointing error is considered for the inter HAP links. Further, the HAP consists of multiantenna array to provide high data-rates to the terrestrial users via RF links, considered to be Nakagami-m distributed. The intermediate HAPs perform selective decode-and-forward relaying and opportunistic user scheduling is performed for the best user selection. For the performance analysis, analytical expression of overall outage probability is obtained and the impact of various selection parameters like pointing error, FSO detection type, MU selection, number of antennas, and RF fading severity are observed on the outage performance. Asymptotic outage probability is also derived to obtain the diversity order of the considered communication system. Further, considering various modulation schemes, a generalized average bit-error-rate expression is derived and the impact of pointing error, FSO detection type, MU selection, number of antennas, and RF fading severity are observed on its performance. Finally, derived results are validated through Monte-Carlo simulations.

EFFECT OF SIMULATED SPACE CONDITIONS ON FUNCTIONAL CONNECTIVITY

Long duration spaceflight missions can affect the cognitive and behavioral activities of astronauts due to changes in gravity. The microgravity significantly impacts the central nervous system physiology which causes the degradation in the performance and lead to potential risk in the space exploration. The aim of this study was to evaluate functional connectivity at simulated space conditions using an unloading harness system to mimic the body-weight distribution related to Earth, Mars, and International Space Station. A unity model with six directional arrows to imagine six different motor imagery tasks associated with arms and legs were designed for the Oculus Rift S virtual reality headset for testing. An Electroencephalogram (EEG) and functional near infrared spectroscopy (fNIRS) signals were recorded from 10 participants in the distributed weight conditions related to Earth, Mars, and International Space station using the g.Nautilus fNIRS system at sampling rate of 500 Hz. The magnitude squared coherence were estimated from left vs right hemisphere of the brain that represents functional connectivity. The EEG coherence was the higher which shows the strong functional connectivity and fNIRS coherence was lower shows weak functional connectivity between left vs right hemisphere of the brain, during all the tasks and trials irrespective of the simulated space conditions. Further analysis of functional connectivity needed between the intra-regions of the brain.

Modeling of Fixed Service Interference in Aeronautical SATCOM Channels

A detailed assessment of the radiofrequency interference from terrestrial fixed service into aeronautical earth stations operating with geostationary satellite orbit networks in the fixed-satellite service is performed. We analyze the impact of the major physical, technical, operational, and regulatory parameters in the interference environment having multiple degrees of freedom to be considered. By performing exhaustive geometric computer simulations, we determine the statistical characteristics of the time-variant radiofrequency interference caused by multiple terrestrial fixed service transmitters using information of existing/registered fixed service stations in France. Subsequently, a stochastic channel model to predict the impact of the terrestrial interference using a higher order finite-state Markov process is developed. Balancing model accuracy and complexity, a reasonable vector quantization clustering algorithm is applied for the partitioning of the interference into representative channel states. For these channel states, we provide a method for scaling this model to different antenna sizes and flight velocities, to be used for development of interference mitigation measures and system design of aeronautical earth stations in motion operating in the 17.7–19.7 GHz frequency range.

Analysis of Velocity Measurement of Radar Signal in Space Vehicle Application using VLSI Chip

The objective of the project is to design a low cost Spectral Monitor for a Space vehicle velocity measurement application, based on Doppler Shift principle by generating an radar signal source from earth station towards moving target device in space and processing received high speed analog 200MHz radar signal from target vehicle device through Antenna, analog pre-processing and FPGA based spectral analyzer. The hardware reconfigurable spectral analyzer design consist of ADC(500MSPS) Interface block, SRAM Memory(1024×16) block, Radix-2 FFT (16 bit DSP block) and LCD Display (Monitoring) driver algorithm implemented On-Chip SOC-FPGA system. The proposed algorithm can be used to meet the need of many real time application such as space exploration, wideband communication, command and control application. The desired algorithm is implemented on-chip reconfigurable hardware SOC-FPGA while keeping the cost, power and area of device low compared to general purpose processor and Embedded based microcontroller. The code architecture is described using hardware description language, VHDL and synthesized and simulated using Xilinx 12.2 ISE Design suite.

Hybrid of Angular and Distance Protection for Coexistence of 5G Base Stations and Satellite Earth Stations

In this study, we investigated the coexistence of the 5G communication network with a fixed-satellite service (FSS) in the 3.5 GHz and 26 GHz frequency bands. We analyzed an angular protection scheme for the FSS Earth station (ES) and 5G base stations (BSs). In addition, we defined the fixed BS-ES relative location, relative distance, and angular changes. The angular protection was integrated into the exclusion and restricted zones proposed by the distance protection scheme for simulation analysis to develop a transmit power control scheme based on the Citizens Broadband Radio Service. Its performances were extensively analyzed through simulations. The proposed scheme was evaluated in practical scenarios: rural macrocells, urban macrocells, and urban microcells, as defined by the 3rd Generation Partnership Project (3GPP). The influence of antenna type was also researched, and BSs with 4 × 4, 8 × 8 and 16 × 16 antenna arrays, as specified by 3GPP, were considered for 5G networks. Finally, the results prove that the angular protection solution can solve the coexistence of the 5G system and the FSS. In addition, when angular protection and distance protection are used simultaneously, the coexistence effect of the two systems can be strengthened. Moreover, this work provides a quantitative perception for selecting system parameters, including an interference margin for the different scenarios and antenna types, the exclusion size, and the reduction area.

An enhanced cross‐layer solution for IFC applications using HTS systems at Q/V‐band

The Q/V band communication systems open new avenues for next generation of high-throughput satellite (HTS) systems. More specifically, they are attractive due to their high bandwidth for user and gateway links. Having a wide bandwidth at Q/V band makes it permissible to offload the links between the satellite and its earth station hubs (gateway) from the Ka band to the Q/V band. This enables additional bandwidth available for HTS feeder links and user links of specific market verticals, which in turn results in reduction of cost per bit for in-flight connectivity applications to provide WiFi capability on the aircraft. This study provides a deep overview of network architecture at the ground gateway infrastructure with respect to the network management system (NMS) to optimize network traffic utilization. We have looked at a gateway constellation platform which optimizes the actual cost-efficient solution for deploying routing user traffic among the networks. In addition, the study discusses the elements involved in the NMS which interfaces with the gateway platform. The overall NMS platform design and capabilities are discussed as they provision the network service parameters throughout the entire operation. The proposed solution integrates the physical antenna, antenna control unit and the power supply into one bundle on the aircraft. This will result in approximately 10% throughput increase compared to conventional methods that do not deploy N+P gateway architecture. The proposed method has enhanced spectrum efficiency along with the NMS unit that has been discussed in detail. Finally, a wideband and multibeam antenna is introduced as an essential part of the solution followed up by simulation results.

2.2 Ghz S-Band Helical Antenna Design for Earth Surveillance LAPAN-TUBSAT Data Acquisition in Indonesia Regional Security

It is necessary to have an LAPAN-TUBSAT (Lembaga Penerbangan dan Antariksa Nasional/ National Institute of Aeronautics and Space) (Technische University of Berlin Satellite) satellite data receiving system that is low cost and can be placed in various parts of Indonesia. This system will later spear head the data receiver and this meets all areas detected by the earth surveillance method in real time and can be recorded at the Earth Station. By using a helical antenna that is engineered independently with the rules of the S band at 2.22 GHz, it will be able to control the Indonesian region. The construction of this receiving antenna uses a helical antenna, a receiver antenna system that combines helix asa feed horn on a parabolic antenna is designed to be able to work at a center frequency of 2,220 MHz, a bandwidth of 27 MHz, LHCP polarization, and a minimum gain of 10 dB. With a Parabolic shaped reflection antenna with Prime Focus. With motor antenna is a full motion antenna with a perstep movement of 0.25 degrees on Azimuth and elevation. The Design will be acquisition the data from satellite, and with the helical antenna. The Helical that by requirement of the 2,22 GHz design. With the LHCP (Left Hand Circular Polarization) and with the a bandwidth of 27 MHz. for the antenna parabola as a catcher of signal from satellite we use type of Primefocus wichis the point focal in the central face of parabola and we will put feed Horn that include inside is the Helical feed antenna. Antenna have a spesification Movement is 0,25 degrees per second With the successful engineering of the development of Helical antenna, it can also later apply it to various other satellites with adjustments to the dimensions of the antenna only and the receiving system.

Robust secure beamforming algorithm for intelligent reflecting surface-assisted satellite-terrestrial integrated networks

For intelligent reflection surface (IRS) assisted satellite-terrestrial integrated network (STIN), a robust secure beamforming method based on the imperfect channel state information (CSI) of eavesdroppers is proposed. First of all, considering that the satellite uses spot beam technology to serve the earth station, while the ground base station (BS) serves multiple ground users through multicast technology, and in the case of frequency spectrum shared between the two networks, a joint optimization problem is formulated to minimize the total transmit power of STIN while satisfying the quality of service constraints of the BS users and the achievable secrecy rate constraints of the earth station. Secondly, in order to solve this non-convex problem, the upper bound and the lower bound of the eavesdroppers’ output signal-to-noise ratio under the condition of imperfect CSI are derived by employing triangle inequality together with Holder inequality. Then, a joint optimization scheme of robust BF and power control based on semi-positive definite programming and penalty function method is proposed to realize the secure and reliable transmission in STIN. Finally, the simulation results verify the effectiveness and superiority of the proposed algorithm.

Feasibility of Using Beam Steering to Mitigate Ku-Band LEO-to-GEO Interference

Low-Earth orbiting (LEO) satellites now hold promise to provide broadband service anywhere in the world, but they must share the radio spectrum with geosynchronous Earth-orbiting (GEO) satellites. The United Nations International Telecommunications Union (ITU) and the U.S. Federal Communications Commission (FCC) require that operators of LEO satellite systems avoid interfering with GEO satellite systems even though both use the same bands within the radio spectrum. Such interference can occur when a LEO satellite passes through an area between a GEO earth station and its intended GEO satellite. This is called an in-line event. In this paper we develop a first order estimate of the probability of occurrence of such an event, an indication that Ku-band LEO-to-GEO interference is a serious problem. We describe the use of beam steering to mitigate such interference and consider its feasibility for currently deployed LEO constellations. We find that beam steering appears to be a practical and effective approach for a LEO constellation that has this capability and uses sufficiently narrow beams.

INTERFERENCE ANALYSIS OF UWB DEVICES TO THE SATELLITE SERVICES IN THE 7240-8240 MHZ FREQUENCY BAND

Ultra-wideband radio technology (UWB), is a wireless access technology that allows exchanging of data over a radio channel between over short distances at very high speed and low power consumption. UWB signals are short pulses the entire energy of which is distributed over a given wide region of the spectrum. With a sufficiently high total power transmitted over the air and with low power consumption and a pulsed nature of data transmission, a high data transmission rate can be obtained. This work has done interference analysis of ultra-wide bandwidth technologies (UWB) operating in the frequency band 7240-8240 MHz to the Earth monitoring and meteorological satellite systems that operate in this band. Taking into account the rapid development of users’ UWB devices in different frequency bands, the study tries to estimate the long-term impact of aggregate interference from UWB devices located around the satellite Earth stations. The study considers two satellite systems as an example of victim receivers. The UWB density assumptions made in the studies are based on the forecasts of CEPT and UWB Alliance.

The CODYSUN Approach: A Novel Distributed Paradigm for Dynamic Spectrum Sharing in Satellite Communications.

With a constant increase in the number of deployed satellites, it is expected that the current fixed spectrum allocation in satellite communications (SATCOM) will migrate towards more dynamic and flexible spectrum sharing rules. This migration is accelerated due to the introduction of new terrestrial services in bands used by satellite services. Therefore, it is important to design dynamic spectrum sharing (DSS) solutions that can maximize spectrum utilization and support coexistence between a high number of satellite and terrestrial networks operating in the same spectrum bands. Several DSS solutions for SATCOM exist, however, they are mainly centralized solutions and might lead to scalability issues with increasing satellite density. This paper describes two distributed DSS techniques for efficient spectrum sharing across multiple satellite systems (geostationary and non-geostationary satellites with earth stations in motion) and terrestrial networks, with a focus on increasing spectrum utilization and minimizing the impact of interference between satellite and terrestrial segments. Two relevant SATCOM use cases have been selected for dynamic spectrum sharing: the opportunistic sharing of satellite and terrestrial systems in (i) downlink Ka-band and (ii) uplink Ka-band. For the two selected use cases, the performance of proposed DSS techniques has been analyzed and compared to static spectrum allocation. Notable performance gains have been obtained.

Investigation of the Directional Characteristics of the Antenna of the Satellite Earth Station Using the Spiral Scanning Method

Results of earth station antenna experimental studies of satellite communication were shown. This antenna looks like two-mirror construction designed by Cassegrain circuit with parabolic reflector, which diameter is 1.2 m. This results made with help of spherical scanner by spiral scanning method. Antenna directional patterns were constructed. Deviation reasons of the measured directional characteristics from the calculated ones were analyzed

Construction of Space Quantum Information System Based on Satellite Recognition

Satellite identification is a form of space quantum information, which refers to the use of artificial earth satellites as the transmitting station between earth communication stations to perform satellite identification to construct a space quantum information system. However, at this stage, a single form of identification cannot meet the needs of various aspects such as the development of the information society. And mobile broadband services. Based on this, this paper has carried out research on the construction of space quantum information system based on satellite recognition. This paper firstly introduces the research significance of space quantum information transmission based on satellite identification, and then analyzes the research status of space information system based on satellite identification and the research status of space quantum information system based on satellite identification at home and abroad. Aiming at the problem of asymmetrical transmission of space information, this paper proposes, a spatial asymmetric transmission scheme based on layered modulation and network coding, and in view of the low communication quality caused by the influence of weather and surrounding environment on the space-based communication channel, this paper proposes an adaptive transmission scheme of spatial information based on satellite cooperation. The survey results show that under the MNC strategy and the traditional zero-padded strategy, the end-to-end bit error rate performance of S2 is not much different. As the signal-to-noise ratio continues to increase to 30dB, the two are basically the same. In the whole range of k value, the access probability of the MNC strategy is equal to a constant 0.67 and remains unchanged. When k=1, under the OUS scheme, it shows that the two source nodes have the same probability of accessing the channel, and the access probability is 50%, which is 16.7% lower than that of the MNC scheme.