Satellite Capacity Research Articles

Enhancing the Capacity of Large LEO Satellites with Internetworked Small Piggybacks for Low Latency Payload Data Transmission

Enhancing the Capacity of Large LEO Satellites with Internetworked Small Piggybacks for Low Latency Payload Data Transmission

Service blockage on the downlink in large-scale satellite optical networks: a multi-downlink scheduling for routing selection

Over years of space laser communication technology advances, satellite optical networks (SONs) have emerged as a pivotal component in 6 G networks. Satellite services are transmitted from the global view, undergoing transmission through SONs, and being downloaded to the targeted areas. However, the transmission capacity of satellites passing through the areas where users are concentrated may be insufficient to download services transmitted worldwide. This problem exists in various kinds of satellite networks and may cause a large amount of service congestion. In this paper, we propose a multi-downlink delivery routing selection (MDD-RS) strategy to study the total utilization of transmission capacity of SONs. We construct an integer linear programming (ILP) model to establish an optimal case study for minimal network capacity occupation. Also, we design an online option, MDD-RS heuristic algorithm, dynamically calculating path routes, considering bandwidth allocation and resource constraints. A comparative analysis against the conventional single-downlink scheme reveals superior performance of the MDD-RS heuristic algorithm, with a reduction in blocking probability of 0.129 and an improvement in bandwidth utilization of 0.032.

Multiobjective Optimization for Beam Hopping and Power Allocation in Dual Satellite Cooperative Transmission Networks

Since single satellite capacity is limited for hotspot areas, we propose a dual satellite (DS) cooperative transmission network to increase the number of served cells and improve the quality of service (QoS) in this article. We study the global beam hopping and power allocation in the proposed network, where the conflict between cell priority and latency is balanced. Due to the beam power impacting both cochannel interference and capacity, the two multiobjective problems are coupled. The plural method is introduced to simplify the coupled problems, which obtains a better QoS than the fixed-weight method. As the dimensionality of the beam hopping pattern increases with the number of cells, global beam hopping design is a dimensional explosion problem. The demand-weighted power (DWP)-adaptive particle marching (APM) algorithm includes roulette, stochastic exploration, and nonlinear weights strategies. It is proposed to handle high-dimensional problems and converge fast to better optimal solutions. The simulation results show that the DWP-APM algorithm performs better with a few particles than the four baseline algorithms. Compared with baseline algorithms, the DWP-APM algorithm reduces the computation time by 57% and improves the QoS level by 13.6% at least.

Sparse Bandit Learning Based Location Management for Space-Ground Integrated Networks

The Space-Ground Integrated Network (SGIN) concept constitutes a promising solution for providing seamless global coverage. However, the mobility of satellites and wireless terminals imposes unprecedented challenges on the location management in SGIN. We tackle this challenge by conceiving a split identifier (ID) and Network Address (NA) based design for providing natural mobility support, and characterize the ID-NA mapping allocation problem by exploiting the storage capacity of both Geostationary Earth Orbit Satellites (GEOSs) and Low Earth Orbiting Satellites (LEOSs) to form a spatially distributed binding resolution system and optimize the caching reward in each LEOS. By considering the large quantity of ID-NA mapping and the sparsity of popular mapping having positive mean caching rewards, we formulate the mapping allocation problem as a sparse Multi-Armed Bandit (MAB) learning procedure, where the mappings are treated as the arms and the LEOSs act as the players. A distributed learning algorithm, namely the Sparse Upper confidence bound based Learning aided Caching algorithm (SULC), is proposed for estimating the mean caching rewards of mappings and selecting the optimal mappings for caching. Moreover, we derive a sub-linear upper bound of the cumulative learning regret to prove the learning efficiency of the proposed SULC. Extensive simulations have been conducted to show that the proposed SULC can quickly identify the popular mappings and provide near-optimal content hit rates. In contrast with the existing solutions, SULC has higher caching rewards and can significantly reduce the cumulative regret after a short period of learning.

Multi-domain united link adaptation technique in high-throughput satellite communication system

Under the condition of using the same frequency resources, the communication capacity of high-throughput satellites is tens or even hundreds of times higher than that of traditional satellites. Compared with traditional satellites, high-throughput satellites have a large capacity, high speed, and anti-interference characteristics. However, the high-throughput satellite communication link using Ku/Ka-band is vulnerable to weather factors such as rain attenuation, so the system should have a control mechanism to achieve fade countermeasures. The existing methods include transmission power adjustment, mod cod adaptive adjustment, carrier symbol rate adjustment, etc. In this paper, various technical means are comprehensively used to compare and analyze the effect of combined control and propose a multi-domain united link adaptation technique to optimize link availability and resource utilization.

High-throughput satellite flexibility design and modeling

The paper presents a high-throughput satellite flexibility modeling and analysis method. The described method gives the design basis for choosing flexible satellite payloads such as transparent digital processors (DTP) for high-throughput satellites. The algorithm in the paper takes different time demands within the high-throughput satellite beams and different area demands between beams as input analyzes the capacity matching rate under the onboard resource constraint in different application scenarios. It also gives the conclusion of whether the satellite chooses a flexible design or not. When the variance of inter-beam demand and design capacity in the coverage area exceeds a given limit, the flexible payload is selected to achieve a higher capacity matching ratio and lower satellite design and usage cost. When the variance of demand and beam design capacity is less than the given limit, the variance of inter-beam demand in the coverage area is smaller, and the satellite system without flexible design is selected considering the full satellite capacity and cost.

Two-Switch Forward Converter With an Integrated Buck Converter for High Bus Voltage in Satellites

As satellite missions become increasingly diverse, the power capacity of satellites continues to increase. Accordingly, the weight and loss of the electrical power system of the satellite must be reduced. Thus, a high bus voltage is required for the electrical power system of the satellite. However, most high-power dc/dc converter topologies, such as half-bridge and full-bridge dc/dc converters have leg-structures, which violate the heritage design characteristics of the dc/dc converters for satellites. To solve these problems, a two-switch forward converter with an integrated buck converter is proposed in this article. By integrating the buck converter into the two-switch forward converter, one switch and one diode are eliminated in the proposed converter, and consequently, its cost, weight, and volume can be greatly reduced. Moreover, the zero-voltage switching of the low-side switch can be achieved. Therefore, the proposed converter achieves a high efficiency under the entire load condition compared with conventional converters. The effectiveness and feasibility of the proposed converter were verified with a prototype of 300–330 V input and 600 W (150 V/100 V) output.

A matheuristic for a 2-echelon vehicle routing problem with capacitated satellites and reverse flows

Last-mile collection and delivery services often rely on multi-echelon logistic systems with many types of practical spatial, temporal, and resource constraints. We consider three extensions of the basic 2-echelon vehicle routing problem that are of practical interest: First, second-echelon vehicles need to simultaneously deliver and collect goods at customers within their specified time window. Second, first-echelon vehicles are allowed to perform multiple trips during the planning horizon. Third, the intermediate facilities, called satellites, allow temporary storage of goods, but the quantity that can be stored at a time is limited. This paper integrates these complicating features in a single mathematical model. To solve the problem, we design a decomposition-based matheuristic. It employs a reduced and refined mixed-integer programming formulation and two echelon-specific large neighborhood searches (LNS) to produce improving routes for the respective echelon. The most important algorithmic component is the feasibility check of LNS that relies on a sequence of constant-time and low-complexity tests. The final test allows re-scheduling of the operations taking place at a satellite. Extensive computational experiments systematically evaluate the new components of the matheuristic and benchmark it against a recent exact method for a related problem. Moreover, the impact of the main problem features such as the number and capacity of satellites as well as the integration of forward and reverse flows is analyzed.

User Capacity Analysis of Space-Based Internet of Things with Multibeam Techniques

Space-based Internet of Things (S-IoT) utilizes the characteristics of satellite network coverage, strong antidestructiveness, and full-time work to realize large-scale sensing and interconnection of everything in the sky, land, sea, and air. The user capacity of S-IoT satellites is mainly determined by beam design, communication schemes, satellite-to-earth links, and communication protocols, which directly affect the system capacity and operational capabilities of S-IoT. This paper proposes an S-IoT satellite user capacity analysis model with multibeam and spread spectrum technology. Taking into account the randomness of user distribution, the difference in transmit power, and different spreading sequences, the user capacity of S-IoT satellites was simulated and compared in different scenarios. Based on these results, this article analyzes the key factors affecting user capacity, which will provide a valuable reference for S-IoT design, link optimization, and power selection.

Enabling In-Flight Connectivity with the new Generation of Electronically Steered Antennas

In-flight communication (IFC) services offered to passengers and crew are of great importance to the air transport sector. The improvement of the satellite capacity with High Throughput Satellites (HTS) in GEO and the advent of MEO and LEO constellations will support the forecast growth of the IFC market. Antenna equipment for satellite communications will need to address multiple scenarios from G2G (Gate-to-Gate) to multi-operation under GEO-MEO-LEO systems. Under these conditions, antennas with the ability to track multiple satellites and having superior performance and reliability will play a key role. Electronically steered antennas (ESA) have emerged as a viable solution in response to these demands. The EU-funded LESAF project proposes an ESA solution of reduced size and greater efficiency for the next generation of in-flight connectivity services. This will be managed through the requirements definition, system analysis, technology assessment, prototyping and validation of ESAs. The project has successfully passed the first milestone corresponding to requirements consolidation, baseline architecture definition and candidate technology trade-offs. Multi-beam Electronically Steered Antennas, separated apertures for both transmission and reception, a flexible modular approach coupled with planar multilayer integration and an advanced beamformer design are the basis for the proposed concept. The following project phase will be focused on the design and validation of an antenna demonstrator aimed at proving the superior added value of ESAs technological solution for the aviation industry needs.

User Capacity Analysis of Space-Based Internet of Things with Multibeam Techniques

Space-based Internet of Things (S-IoT) utilizes the characteristics of satellite network coverage, strong antidestructiveness, and full-time work to realize large-scale sensing and interconnection of everything in the sky, land, sea, and air. The user capacity of S-IoT satellites is mainly determined by beam design, communication schemes, satellite-to-earth links, and communication protocols, which directly affect the system capacity and operational capabilities of S-IoT. This paper proposes an S-IoT satellite user capacity analysis model with multibeam and spread spectrum technology. Taking into account the randomness of user distribution, the difference in transmit power, and different spreading sequences, the user capacity of S-IoT satellites was simulated and compared in different scenarios. Based on these results, this article analyzes the key factors affecting user capacity, which will provide a valuable reference for S-IoT design, link optimization, and power selection.

Scheduled service network design with resource management for two-tier multimodal city logistics

We address the tactical-planning problem for an extended two-tiered City Logistics system. This more realistic problem setting, compared to the literature, integrates inbound and outbound demands, different transportation modes combining traditional, road-based, carriers with modes and vehicles of mass transport, such as light and regular rail. Aside from the assignment of customers to consolidation distribution centers and satellites, we manage a number of major resources, such as the multiple satellite capacity measures and the structure, allocation, and size of the heterogeneous fleets. We propose a scheduled service network design formulation for the tactical planning of such extended systems, and develop an efficient Benders decomposition algorithm, which includes a tailored partial decomposition technique for deterministic mixed-integer linear-programming formulations. The results of extensive numerical experiments show the efficiency of the proposed solution method, as well as the benefits of integrating several demand types and multimodal transportation networks into a single formulation.

NOMA Application to Satellite Communication Networks for 5G: A Comprehensive Survey of Existing Studies

The 4th generation of communication networks (4G) seems limited and unable to satisfy the growing networks’ performances demands of new intended communication services such as the internet-of-things (IoTs). The 5th generation of communication networks (5G) has therefore been envisaged to fill the gap. The non-orthogonal multiple access (NOMA) technology and the satellite communication have been identified as key enabling technologies for the achievement of 5G networks. There are many ongoing NOMA related works for 5G; however, the few existing reviews mostly discuss works that apply NOMA to terrestrial networks. This paper therefore, gives a comprehensive and up-to-date review of existing works applying NOMA to satellite communication networks. More precisely, it presents studies that have either designed or do performance analysis of NOMA-based multibeam satellitesystems (MBSSs) or integrated satellite-terrestrial networks (ISTNs). The surveys presented showed that the application of NOMA to satellite communications for 5G is starting to gain considerable interest. Most of the current PD-NOMA design works attempt to maximize the system capacity (sum-rate), and most of the current PD-NOMA performance analysis works demonstrate the superiority of NOMA over OMA through Ergodic Capacity and Outage probability estimations. The surveys also showed that this field is still quite opened for research, with issues such as user-fairness maximization, satellite capacity improvement, ground-surface moving beams (for LEOs and MEOs satellites) and multiple gateways combination … etc. remaining prospective research areas to be explored.

An Open Data and Citizen Science Approach to Building Resilience to Natural Hazards in a Data-Scarce Remote Mountainous Part of Nepal

The citizen science approach has gained momentum in recent years. It can enable both experts and citizen scientists to co-create new knowledge. Better understanding of local environmental, social, and geographical contexts can help in designing appropriate plans for sustainable development. However, a lack of geospatial data, especially in the context of developing countries, often precludes context-specific development planning. This study therefore tests an innovative approach of volunteer citizen science and an open mapping platform to build resilience to natural hazards in the remote mountainous parts of western Nepal. In this study, citizen scientists and mapping experts jointly mapped two districts of Nepal (Bajhang and Bajura) using the OpenStreetMap (OSM) platform. Remote mapping based on satellite imagery, capacity building, and mobilization of citizen scientists was performed to collect the data. These data were then uploaded to OSM and later retrieved in ArcGIS to produce a usable map that could be exploited as a reference resource for evidence-based decision-making. The collected data are freely accessible to community members as well as government and humanitarian actors, and can be used for development planning and risk reduction. By piloting in two communities of western Nepal, we found that using open data platforms for collecting and analyzing location-based data has a mutual benefit for researchers and communities. Such data could be vital in understanding the local landscape, environmental risk, and distribution of resources. Furthermore, they enable both researchers and local people to transfer technical knowledge, collect location-specific data, and use them for better decision-making.

LAA: Lattice-Based Access Authentication Scheme for IoT in Space Information Networks

Space information network (SIN), which has the characteristics of large capacity, high reliability, and wide coverage, can be effectively applied to the Internet of Things (IoT) business. However, SIN is vulnerable to various attacks due to its highly exposed links, and the power and processing capacity of satellites and IoT devices (IoTDs) are usually limited. Meanwhile, massive IoTDs connecting to SIN in an instant incur a severe signaling congestion and there is no authentication protocol proposed for massive IoTDs in SIN. In this article, we first propose a novel semi-aggregated signature mechanism and session key agreement mechanism. Then, based on the above two mechanisms, we propose a novel access authentication scheme named lattice-based access authentication (LAA) which contains two types of lattice-based authentication protocols: 1) LAA for massive IoTDs and 2) LAA for a single IoTD. The security analysis by employing the formal provable security analysis, the automation verification tool named Scyther, the Burrows–Abadi–Needham-logic, and the informal security analysis demonstrate that our proposed protocols successfully achieve these security properties, including mutual authentication, conditional anonymity, unlinkability, data confidentiality, data integrity, unforgeability, undeniability, key establishment, perfect forward/backward secrecy (PFS/PBS), and resistance against protocol attacks and quantum attacks. We further evaluate the performance of our proposed protocols with regard to signaling overhead, transmission overhead, computational overhead, and authentication delay, which shows that our proposed protocols can provide high efficiency.

Multi-satellite scheduling framework and algorithm for very large area observation

This paper presents a multi-satellite scheduling problem for very large area observation with given specific constraints, derived from satellite capacity and customer requests. It is assumed that the profit was proportional to the coverage of acquired area, and the objective is therefore to maximize the total profits of generated observation schedule. To address the satellite scheduling problem, we first demonstrate a detailed problem description and then transform the problem into set covering problem within several criteria and constraints. Based on that, a mathematical model is established. In order to solve the multi-satellite scheduling problem for large area observation, a new solving framework is proposed. The framework is composed of three phases. In the discretizing phase, an area discretization method is adopted to establish the evaluation system. In the target decomposing phase, area target is decomposed into strips and corresponding visible time windows are calculated. In the scheduling phase, with crossover, mutation and feasibility operators, a genetic algorithm is introduced to generate an optimal observation schedule. Through extensive computational experiments on realistically generated problem with Chinese satellite platform, the effectiveness and reliability of the proposed solving framework are verified.

Quiescence of human muscle stem cells is favored by culture on natural biopolymeric films

BackgroundSatellite cells are quiescent resident muscle stem cells that present an important potential to regenerate damaged tissue. However, this potential is diminished once they are removed from their niche environment in vivo, prohibiting the long-term study and genetic investigation of these cells. This study therefore aimed to provide a novel biomaterial platform for the in-vitro culture of human satellite cells that maintains their stem-like quiescent state, an important step for cell therapeutic studies.MethodsHuman muscle satellite cells were isolated from two donors and cultured on soft biopolymeric films of controlled stiffness. Cell adhesive phenotype, maintenance of satellite cell quiescence and capacity for gene manipulation were investigated using FACS, western blotting, fluorescence microscopy and electron microscopy.ResultsAbout 85% of satellite cells cultured in vitro on soft biopolymer films for 3 days maintained expression of the quiescence marker Pax7, as compared with 60% on stiffer films and 50% on tissue culture plastic. The soft biopolymeric films allowed satellite cell culture for up to 6 days without renewing the media. These cells retained their stem-like properties, as evidenced by the expression of stem cell markers and reduced expression of differentiated markers. In addition, 95% of cells grown on these soft biopolymeric films were in the G0/G1 stage of the cell cycle, as opposed to those grown on plastic that became activated and began to proliferate and differentiate.ConclusionsOur study identifies a new biomaterial made of a biopolymer thin film for the maintenance of the quiescence state of muscle satellite cells. These cells could be activated at any point simply by replating them onto a plastic culture dish. Furthermore, these cells could be genetically manipulated by viral transduction, showing that this biomaterial may be further used for therapeutic strategies.

Determination of Operational Threshold for Coding and Modulation Combination to Improve The Quality of High Throughput Satellite in Ka-Band Frequency in Indonesia

The vast enhancement of telecommunication technology has encouraged the increase of demand for more satellite capacity. HTS in Ka-Band frequency, that can deliver more capacity up to 50 GHz, can be a solution. Unfortunately, Ka-Band is susceptible to rain attenuation which is potentially difficult to be implemented in Indonesia because of its high rain rate. But, According to the previous research by Suwadi, Marrudani, and Lye, the combination of coding and modulation technique can be used as a solution to improve the performance of service dealing with rain attenuation.
 In this research, the writer will try to improve whether the combination of coding and modulation is also able to improve HTS Ka-Band communication link here ini in Indonesia with the high rain rate per year and to determine threshold of which the combination of coding and modulation that is best suited to each weather condition, in order to get the minimum required performance with BER min = 10 − 8. The conclusion of this research shows that the quality of HTS in Ka-Band frequency in Indonesia with BER = 10 − 8 can be improved by using QPSK, 8-APSK, 16-APSK, and 9 types of FEC. Furthermore, the 17 pairs of ModCod can be categorized into 8 thresholds that will determine with that ModCod that should be used in order to get the link quality of BER = 10 − 8 for each certain rain condition.

Privatizing Space Missions: The Critical Route to Boost Indian Space Economy

Space-based services in India have reached a stage where demand is outpacing supply and is creating a unique opportunity for developing space industry. A major outcome of advances in space, information, and communications technologies, coupled with changes in policy environment in India, immensely favors deregulation of space activities in a strategic manner into a public–private domain; thrusted private sector investments and space assets ownership and operations; space services to burgeoning domestic demand and impacting global businesses; creating high technology manufacturing capability, and competitive alliances and cooperation. Prospects for growth of commercial space activities in India are promising given that there is still high potential for growth in demands for satellite capacity and for new services such as Geographic Information System (GIS) based decision support systems, mobile multimedia, positioning and navigation applications, disaster management support, rural connectivity and national security-related applications. Demand for satellite communications is very high with large downstream services business; constant need for repetitive and high res images from space and other platforms with downstream services potential for National GIS; expanding from a regional to a global positioning system and services and applications; large-scale supply of operational LEO/GEO launch systems capability based on operational Polar Satellite Launch Vehicle (PSLV); catering to global markets of space manufacturing/applications by offering high-quality but cost-effective Indianized solutions are classic cases that can be easily privatized and migrated from present “ISRO regime” to a combinative “ISRO+private sector” capacity for future Indian space success—founding the possibility of Indian private sector space assets ownership and operations. The article creates a case and scenario for a time-bound strategy of “license-buyback” model of thrust for private-sector manufacturing, ownership and operations of Indian space assets—especially communication satellites, EO satellites, PSLV-type launch vehicle, and so on. for space services to meet Indian requirements. This approach will also bring in private sector investment in Indian space releasing financial resources for critical advanced technology development in the public regime of ISRO. The article analyses “sample cases” from an investment scenario assessment, policy dimensions, and risk environment that would be of interest for private-sector development for Indian space.

Radar satellites measure ice cover displacements induced by moving vehicles

Vehicles moving on floating ice modulate its surface depending on ice, bathymetric, and traffic variables. Under certain conditions, they may cause ice cover breakthroughs that jeopardize productivity, property, and life. The initiation of ice cover failure by traffic is commonly referred to as the moving vehicle problem. Scientific progress towards mitigating this problem has been limited. Subject-matter experts have argued that this is due, in part, to the absence of convenient and accurate means to measure ice cover modulations. Here we demonstrate a previously unknown capacity of radar earth observation satellites to measure the modulation of ice cover by moving vehicles with an unparalleled breadth of view, superior spatial detail and millimeter-scale vertical accuracy. This capacity derives from satellite radar technology that is experimental at present and differential interferometric radar data processing techniques. Ice modulations measured by means of conventional devices are typically described as ‘deflections’; we purposely refer to the radar satellite measurements as ‘displacements’ to signify a difference in the measurement method and result. Our findings indicate opportunities for ice road and radar earth observation stakeholders, may spark renewed interest in and progress towards mitigating the moving vehicle problem, and thus help improve the efficiency and safety of ice road transportation.