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With the continuous advancement of cloud computing and satellite communication technology, the cloud-network-integrated satellite network has emerged as a novel network architecture. This architecture harnesses the benefits of cloud computing and satellite communication to achieve global coverage, high reliability, and flexible information services. However, as business types and user demands grow, addressing differentiated Quality of Service (QoS) requirements has become a crucial challenge for cloud-network-integrated satellite networks. Effective resource allocation algorithms are essential to meet these differentiated QoS requirements. Currently, research on resource allocation algorithms for differentiated QoS requirements in cloud-network-integrated satellite networks is still in its early stages. While some research results have been achieved, there persist issues such as high algorithm complexity, limited practicality, and a lack of effective evaluation and adjustment mechanisms. The first part of this study examines the state of research on network virtual mapping methods that are currently in use. A reinforcement-learning-based virtual network mapping approach that considers quality of service is then suggested. This algorithm aims to improve user QoS and request acceptance ratio by introducing QoS satisfaction parameters. With the same computational complexity, QoS is significantly improved. Additionally, there has been a noticeable improvement in the request acceptance ratio and resource utilization efficiency. The proposed algorithm solves existing challenges and takes a step towards more practical and efficient resource allocation in cloud-network-integrated satellite networks. Experiments have proven the practicality of the proposed virtual network embedding algorithm of Satellite Network (SN-VNE) based on Reinforcement Learning (RL) in meeting QoS and improving utilization of limited heterogeneous resources. We contrast the performance of the SN-VNE algorithm with DDRL-VNE, CDRL, and DSCD-VNE. Our algorithm improve the acceptance ratio of VNEs, long-term average revenue and delay by an average of 7.9%, 15.87%, and 63.21%, respectively. [ABSTRACT FROM AUTHOR]

Summary: Cellular networks are projected to deal with an immense rise in data traffic, as well as an enormous and diverse device, plus advanced use cases, in the nearest future; hence, future 5G networks are being developed to consist of not only 5G but also different radio access technologies (RATs) integrated. In addition to 5G, the user's device (UD) will be able to connect to the network via LTE, WiMAX, WiFi, Satellite and other technologies. On the other hand, Satellite has been suggested as a preferred network to support 5G use cases. However, achieving load balancing is essential to guarantee an equal amount of traffic distributed between different RATs in a heterogeneous wireless network; this would enable optimal utilisation of the radio resources and lower the likelihood of call blocking/dropping. This study presented an artificial intelligent‐based application in heterogeneous wireless networks and proposed an enhanced particle optimisation (EPSO) algorithm to solve the load balancing problem in 5G‐Satellite networks. The algorithm uses a call admission control strategy to admit users into the network to ensure that users are evenly distributed on the network. The proposed algorithm was compared with the Artificial Bee Colony and Simulated Annealing algorithm using three performance metrics: throughput, call blocking and fairness. Finally, based on the experimental findings, results outcomes were analysed and discussed. [ABSTRACT FROM AUTHOR]

The expansion of megaconstellation networks (MCNs) represents a promising solution for achieving global Internet coverage. To meet the growing demand for satellite services, multipath routing allows the simultaneous establishment of multiple transmission paths, enabling the transmission of flows in parallel. Nevertheless, the mobility of satellites and time-varying link states presents a challenge for the discovery of optimal paths and traffic scheduling in multipath routing. Given the inflexibility of traditional static deep reinforcement learning (DRL)-based routing algorithms in dealing with time-varying constellation topologies, DRL-based multipath routing (DMR) enabled by a graph neural network (GNN) is proposed as a means of enhancing the transmission performance of MCNs. DMR decouples the stochastic optimization problem of multipath routing under traffic and bandwidth constraints into two subproblems: multipath routing discovery and multipath traffic scheduling. Firstly, the minimum hop count-based multipath route discovery algorithm (MHMRD) is proposed for the computation of multiple available paths between all source and destination nodes. Secondly, the GNN-based multipath traffic scheduling scheme (GMTS) is proposed as a means of dynamically scheduling the traffic on each available path for each data stream, based on the state information of ISLs and traffic demand. Simulation results demonstrate that the proposed scheme can be scaled to constellations with different configurations without the necessity for repeated training and enhance the throughput, completion ratio, and delay by 42.64%, 17.39%, and 3.66% in comparison with the shortest path first algorithm (SPF), respectively. [ABSTRACT FROM AUTHOR]

In recent years, with the development of low‐earth orbit broadband satellites, the combination of multi‐path transmission and software‐defined networking (SDN) for satellite networks has seen rapid advancement. The integration of SDN and multi‐path transmission contributes to improving the efficiency of transmission and reducing network congestion. However, the current SDN controllers do not support the multi‐path QUIC protocol (MPQUIC), and the routing algorithm used in current satellite networks based on minimum hop count struggles to meet the real‐time requirements for some applications. Therefore, this paper designs and implements an SDN controller that supports the MPQUIC protocol and proposes a multi‐objective optimization‐based routing algorithm. This algorithm selects paths with lower propagation delays and higher available bandwidth for subflow transmission to improve transmission throughput. Considering the high‐speed mobility of satellite nodes and frequent link switching, this paper also designs a flow table update algorithm based on the predictability of satellite network topology. It enables proactive rerouting upon link switching, ensuring stable transmission. The performance of the proposed solution is evaluated through satellite network simulation environments. The experimental results highlight that SDN‐MPQUIC significantly improves performance metrics: it reduces average completion time by 37.3% to 59.3% compared to QSMPS and by 52.8% to 72.4% compared to Disjoint for files with different sizes. Additionally, SDN‐MPQUIC achieves an average throughput improvement of 81.4% compared to QSMPS and 147.8% compared to Disjoint, while demonstrating a 26.3% lower retransmission rate than QSMPS. [ABSTRACT FROM AUTHOR]

One of the major challenges arising in internet of military things (IoMT) is accommodating massive connectivity while providing guaranteed quality of service (QoS) in terms of ultra-high reliability. In this regard, this paper presents a class of code-domain nonorthogonal multiple accesses (NOMAs) for uplink ultra reliable networking of massive IoMT based on tactical datalink such as Link-16 and joint tactical information distribution system (JTIDS). In the considered scenario, a satellite equipped with Nr antennas servers K devices including vehicles, drones, ships, sensors, handset radios, etc. Nonorthogonal coded modulation, a special form of multiple input multiple output (MIMO)-NOMA is proposed. The discussion starts with evaluating the output signal to interference-plus-noise (SINR) of receiver filter, leading to the unveiling of a closed-form expression for overloading systems as the number of users is significantly larger than the number of devices admitted such that massive connectivity is rendered. The expression allows for the development of simple yet successful interference suppression based on power allocation and phase shaping techniques that maximizes the sum rate since it is equivalent to fixed-point programming as can be proved. The proposed design is exemplified by nonlinear modulation schemes such as minimum shift keying (MSK) and Gaussian MSK (GMSK), two pivotal modulation formats in IoMT standards such as Link-16 and JITDS. Numerical results show that near capacity performance is offered. Fortunately, the performance is obtained using simple forward error corrections (FECs) of higher coding rate than existing schemes do, while the transmit power is reduced by 6 dB. The proposed design finds wide applications not only in IoMT but also in deep space communications, where ultra reliability and massive connectivity is a keen concern.

High bit error rate (BER), long delay, dynamic networking and multi-hop nature of satellite networks can affect the transmission performance of integrated networks, which poses a great challenge to the transmission performance of space-air-ground integrated networks constructed by satellite networks and terrestrial multi-hop networks. In order to improve the transmission rate of heterogeneous converged satellite networks and terrestrial multi-hop networks, this study proposed a scheme applicable to the transmission characteristics. By analyzing the transmission characteristics of satellite networks with long delay and high BER and terrestrial wireless multi-hop networks, the data delivery in the slow start-up phase was improved, and the type of lost data in the congestion avoidance phase was discriminated to enhance the transmission performance of the heterogeneous integrated network. The performance of the proposed scheme was further verified by simulation on OPNET software. Results show that, the proposed scheme not only can effectively reduce the queuing delay of nodes but also can enhance the transmission efficiency of multi-hop network terminals and the data transmission rate in the long delay network environment. With the increase in the number of hops, the transmission rate of the proposed protocol is about twice those of other protocols. Therefore, the proposed scheme can help improve the transmission performance of heterogeneous integrated satellite networks and terrestrial multi-hop networks. [ABSTRACT FROM AUTHOR]

This paper discusses the reliability deployment of Service Function Chain (SFC) on the hybrid satellite network based on SDN architecture. Firstly, this paper describes the reliability protection problem of SFC, establishes the underlying network and SFC request model, and then establishes the reliability requirement model of network service function and the reliability requirement model of LEO satellite link, and clarifies the optimization goals and constraints. Then, a reliability-based satellite service function chain protection method is proposed, including a reliability protection algorithm based on deep reinforcement learning and a reliability backup algorithm based on LEO satellite node and link. Experiments show that the proposed reliability-based satellite service function chain protection method can improve the SFC request acceptance rate, reduce the average delay, and maintain high request acceptance on hybrid satellite networks based on SDN architecture.

Satellite mobile communication networks can provide communication services in areas beyond the coverage of terrestrial cellular networks. Ground relay stations for satellite networks is an effective solution to improve the coverage quality and to ensure connectivity between regular ground terminals and the satellite network. Without power grid coverage, the ground relay station can only be powered by green energy generation devices. So the problem of energy-saving under sleep strategy is worthy of studying.This paper proposes an energy-saving sleep control method for ground relay stations through Double Deep Q Network (DDQN) algorithm. Based on the traditional rule-based method that is only set for residual energy, it also considers the impact of weather factors on solar and wind power generation on the energy efficiency of relay stations. The research results show that by considering multiple influencing factors at the same time, the method used in this paper can effectively save non-communication energy consumption at low loads, ensure the satellite communication needs of most users, and improve the operational energy efficiency of the relay station over a period of time.

In recent years, satellite networks have been proposed as an essential part of next-generation mobile communication systems. Software defined networking techniques are introduced in satellite networks to handle the growing challenges induced by time-varying topology, intermittent inter-satellite link and dramatically increased satellite constellation size. This survey covers the latest progress of software defined satellite networks, including key techniques, existing solutions, challenges, opportunities, and simulation tools. To the best of our knowledge, this paper is the most comprehensive survey that covers the latest progress of software defined satellite networks. An open GitHub repository is further created where the latest papers on this topic will be tracked and updated periodically. Compared with these existing surveys, this survey contributes from three aspects: (1) an up-to-date SDN-oriented review for the latest progress of key techniques and solutions in software defined satellite networks; (2) an inspiring summary of existing challenges, new research opportunities and publicly available simulation tools for follow-up studies; (3) an effort of building a public repository to track new results.

The problem of multiple DAGs sharing satellite constellation resources has gradually attracted widespread attention. Due to the limited computing resources and energy consumption of satellite networks, it is necessary to formulate a reasonable multi-DAG task scheduling scheme to ensure the fairness of each workflow under the premise of considering latency and energy consumption. Therefore, in this paper, we propose a multi-DAG satellite network task scheduling algorithm based on cache-composite priority under the Software-Defined Networking satellite network architecture. The basic idea of this algorithm lies in the DAG selection phase, where not only are task priorities computed but also the concept of fair scheduling is introduced, so as to prevent the excessively delayed scheduling of low-priority DAG tasks. In addition, the concept of public subtasks is introduced to reduce the system overhead caused by repetitive tasks. The experimental results show that the hybrid scheduling strategy proposed in this paper can meet the demand of DAG scheduling and improve the degree of task completion while effectively reducing the task latency and energy consumption. [ABSTRACT FROM AUTHOR]

This paper discusses the reliability deployment of Service Function Chain (SFC) on the hybrid satellite network based on SDN architecture. Firstly, this paper describes the reliability protection problem of SFC, establishes the underlying network and SFC request model, and then establishes the reliability requirement model of network service function and the reliability requirement model of LEO satellite link, and clarifies the optimization goals and constraints. Then, a reliability-based satellite service function chain protection method is proposed, including a reliability protection algorithm based on deep reinforcement learning and a reliability backup algorithm based on LEO satellite node and link. Experiments show that the proposed reliability-based satellite service function chain protection method can improve the SFC request acceptance rate, reduce the average delay, and maintain high request acceptance on hybrid satellite networks based on SDN architecture. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the public land mobile communication network transitioning from the 5G era where information flows freely to the 6G era where everything is interconnected, satellite networks have become a hot development topic all around the world.At the same time, with the improvement of satellite on-board computing capabilities and the integration of computing and satellite networks, cloud network integration has become a new development trend.On the basis of a brief introduction to the current development status of satellite networks and satellite computing, the development roadmap of satellite network development architecture was summarized.Then, a satellite network architecture based on cloud-network integration (i.e.satellite cloud network) was proposed, and the advantages of satellite cloud network architecture from five aspects: computing driven communication enhancement, computing driven network enhancement were analyzed, computing driven service enhancement, computing driven control enhancement, and computing driven management enhancement.

Satellite network has attracted extensive attention from academia and industry due to its characteristics of wide coverage, high bandwidth, strong survivability, natural broadcast and so on. However, due to the characteristics of long propagation delay, high bit error rate and asymmetric bandwidth, the traditional TCP protocol has poor performance in satellite network. In recent years, with the rapid development and large-scale deployment of the giant constellations represented by "Starlink", the satellite network has shown the characteristics of high dynamics, which poses a severe challenge to the high-performance transmission of satellite constellation network. This paper summarizes the research progress of new technologies for satellite network transport protocol optimization that have emerged in recent years. Especially, the new technologies represented by multi-path transmission, QUIC, intelligent transmission optimization are deeply compared and analyzed. [ABSTRACT FROM AUTHOR]

The rapid development of sixth-generation (6G) mobile broadband networks and Internet of Things (IoT) applications has led to significant increases in data transmission and processing, resulting in severe traffic congestion. To better allocate network resources, predicting network traffic has become crucial. However, satellite networks face global imbalances in IoT traffic demand, with substantial variations in satellite density and load distribution within the same constellation. These disparities render traditional traffic prediction algorithms inadequate for dynamically changing satellite network topologies. This paper thoroughly examines the impact of adaptive time stepping on the prediction of dynamic traffic load. Particularly, we propose a high-speed traffic prediction method that employs machine learning and recurrent neural networks over the 6G Space Air Ground Integration Network (SAGIN) structure. In our proposed method, we first investigate a variable step size-normalized least mean square (VSS-NLMS) adaptive prediction method for transforming time series prediction datasets. Then, we propose an adaptive time stepping-Gated Recurrent Unit (ATS-GRU) algorithm for real-time network traffic prediction. Finally, we compare the prediction accuracy of the ATS-GRU algorithm with that of the fixed time stepping-Gated Recurrent Unit (FTS-GRU) algorithm and compared the prediction results of three different step sizes (FSS, VSS, and ATS) based on normalized least mean square (NLMS). Numerical results demonstrate that our proposed scheme can automatically choose a suitable time stepping to track and predict the traffic load curve with acceptable accuracy and reasonable computational complexity, as its time stepping dynamically adjusts with the traffic. [ABSTRACT FROM AUTHOR]

Communication between a nanosatellite located in Low Earth Orbit (LEO) and a ground station is limited in regions far from the poles, occurring for only a few minutes on different days and at different times. By utilizing satellite-to-satellite communication, it is possible to transmit and receive information more efficiently, circumventing the restrictions inherent in satellite-ground station links. The objective of this study is to present a comparative report on the results of data transmission through inter-satellite and satellite-to-ground station communication, focusing on a 1U CubeSat nanosatellite (AztechSat-1). This paper discusses the use of the GlobalStar network and a nanosatellite for inter-satellite communication. This paper also discusses the use of proprietary and open-source ground stations for satellite-ground communication. We provide an overview of the GlobalStar network and the associated ground stations involved in this research, along with the results and their subsequent analysis. [ABSTRACT FROM AUTHOR]

Copyright of Space-Integrated-Ground Information Networks is the property of Beijing Xintong Media Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the space environment, cosmic rays and high-energy particles may cause a single-event upset (SEU) during program execution, and further cause silent data corruption (SDC) errors in program outputs. After extensive research on SEU and SDC errors, it has been found that SDC errors in the routing program in satellite networks may lead to the emergence of Sinkhole (SH) and Grayhole (GH) nodes in the network, which may cause damage to satellite networks. To find and solve the problems in time, a digital-twin-based detection and protection framework for SDC-induced SH and GH nodes in satellite networks is proposed. First, the satellite network fault model under SEU and the generation mechanism of SH and GH nodes induced by SDC errors are described. Then, the data structure based on digital twins required by the proposed detection and protection framework is designed, and the detection methods of SH and GH nodes induced by SDC errors are proposed. SKT and LLFI simulation tools are used to build a simulated Iridium satellite network and carry out fault injection experiments. Experiment results show that the accuracy of the proposed detection method is 98–100%, and the additional time cost of routing convergence caused by the proposed framework is 3.1–28.2%. Compared with existing SH and GH detection methods, the proposed methods can timely and accurately detect faults during the routing update stage. [ABSTRACT FROM AUTHOR]

The continuous growth of satellite network scale brings great challenges to the eff ective scheduling of TT＆amp;C resources.Aff ected by weather and other factors, the performance of the satellite-ground link is of high uncertainty.In order to took into both resource utilization and task reliability, a robust scheduling method of TT＆amp;C resources was proposed.This method could arranged the start time and duration of the transmission window for TT＆amp;C tasks by the predicted the channel state distribution of satelliteground link and the task distribution in the planning period, and optimized the resource allocation scheme by backward iteration to maximized the expected profit of the tasks.The experimental results showed that compared with the traditional non-robust scheduling method, the scheduling method proposed could obtain more task profi t under diff erent channel distributions and achieve the improvement of both resource utilization and task reliability.

With the advancement of space technology and satellite communications, low-Earth-orbit (LEO) satellite networks have experienced rapid development in the past decade. In the vision of 6G, LEO satellite networks play an important role in future 6G networks. On the other hand, a variety of applications, including many delay-sensitive applications, are continuously emerging. Due to the highly dynamic nature of LEO satellite networks, supporting time-deterministic services in such networks is challenging. However, we can provide latency guarantees for most delay-sensitive applications through data plane traffic shaping and control plane routing optimization. This paper addresses the routing optimization problem for time-sensitive (TS) flows in software-defined low-Earth-orbit (LEO) satellite networks. We model the problem as an integer linear programming (ILP) model aiming to minimize path handovers and maximum link utilization while meeting TS flow latency constraints. Since this problem is NP-hard, we design an efficient longest continuous path (LCP) approximation algorithm. LCP selects the longest valid path in each topology snapshot that satisfies delay constraints. An auxiliary graph then determines the routing sequence with minimized handovers. We implement an LEO satellite network testbed with Open vSwitch (OVS) and an open-network operating system (ONOS) controller to evaluate LCP. The results show that LCP reduces the number of path handovers by up to 31.7% and keeps the maximum link utilization lowest for more than 75% of the time compared to benchmark algorithms. In summary, LCP achieves excellent path handover optimization and load balancing performance under TS flow latency constraints. [ABSTRACT FROM AUTHOR]

Copyright of Frontiers of Information Technology & Electronic Engineering is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent years, major natural disasters and public safety accidents have frequently occurred worldwide. In order to deal with various disasters and accidents using rapidly deployable, reliable, efficient, and stable emergency communication networks, all countries in the world are strengthening and improving emergency communication network construction and related technology research. Motivated by these situations, in this paper, we provide a state-of-the-art survey of the current situation and development of emergency communication networks. In this detailed investigation, our primary focus is the extensive discussion of emergency communication network technology, including satellite networks, ad hoc networks, cellular networks, and wireless private networks. Then, we explore and analyze the networks currently applied in emergency rescue, such as the 370M narrowband private network, broadband cluster network, and 5G constellation plan. We propose a broadband-narrowband integrated emergency communication network to provide an effective solution for visual dispatch of emergency rescue services. The main findings derived from the comprehensive survey on the emergency communication network are then summarized, and possible research challenges are noted. Lastly, we complete this survey by shedding new light on future directions for the emergency communication network. In the future, the emergency network will develop in the direction of intelligence, integration, popularization, and lower cost, and space-air-ground-sea integrated networks. This survey provides a reference basis for the construction of networks to mitigate major natural disasters and public safety accidents. [ABSTRACT FROM AUTHOR]

The development of computer technology and network technology makes network‐oriented three‐dimensional (3D) visualization an important development direction in the computer field. And the arrival of the era of big data makes it irreplaceable in dynamic simulation, disaster simulation, and supporting decision‐making of geographic information systems (GIS). However, the composition in GIS is not static, but dynamically changing, even moving at high speed, such as various transportation vehicles, which brings great challenges to real‐time and accurate visualization. How to realize real‐time visualization of dynamically changing GIS is of urgent significance. In this paper, the characteristics of real‐time positioning of satellite network are considered to design a visualization and analysis method based on satellite network for 3D geographic information (SN‐3DGVA). It can sense the change of objects and locate the corresponding change tracks and position, so as to perform 3D geographic visualization analysis. [ABSTRACT FROM AUTHOR]

Copyright of Space-Integrated-Ground Information Networks is the property of Beijing Xintong Media Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In satellite network, different nodes have different effects on network connectivity and throughput.In order to avoid network communication disturbances caused by the failure of key nodes in the satellite network, network planning can be carried out in advance by measuring the importance of satellite network nodes.According to the characteristics of satellite network information heterogeneity, satellite virtual nodes and virtual sub-layers were defined, and the satellite multi-layer heterogeneous information correlation network model was proposed.The normalized degree, normalized node betweenness and virtual node correlation factor of virtual nodes were defi ned, and the network node importance calculation function was proposed through the defined parameters, which could accurately measured the node importance in the satellite multi-layer heterogeneous information network.Based on typical examples, the network connectivity and throughput indicators were analyzed.The results showed that the proposed algorithm was better than the classical graph theory algorithm, which could comprehensively considered the impact of data information on the importance of network nodes, and more accurately described the connectivity index of satellite multi-layer heterogeneous information networks.

The important role satellite communications plays in next-generation communication protocols brings both opportunities and challenges.Beamforming is an essential technology for effi cient and fl exible utilization of onboard resources.To explored a better beamforming technology, the optical control beamforming composed of the optical real-time delay line and the traditional analog beam were compared in principle.The phased array beamforming technology based on optical true time delay line meets the expectations of small size, lightweight, and low power in satellite communication.Phased arrays based on optical true delay lines could easily achieved no squint during beam scanning.The technical advantages and constraints of beamforming of optical real-time delay lines under diff erent technical paths were analyzed.For example, based on micro-ring resonator arrays, based on grating delay lines, based on multi-path switching and optical switches, and based on wavelength-selective optical true time delay lines.Finally, the research status of the existing optical beamforming technology was summarized.The possibility of realization in satellite interconnection was proposed, and its future development direction was predicted.

Satellite networks can communicate with the outside world from anywhere in the world, and multihop networks are suitable for occasions in which infrastructure is lacking or for emergencies. Heterogeneous networks formed by satellite and multihop networks can further expand the communication range of wireless networks; this expansion is conducive to communication with the outside world in remote areas and in emergency situations. However, the formation of heterogeneous networks also brings new challenges to wireless network research. To improve the transmission performance of heterogeneous networks composed of satellite and multihop networks, this paper first introduces the heterogeneous network model of satellite and multihop networks, then analyzes the bandwidth delay products of heterogeneous networks and proposes an end-to-end transmission control algorithm for heterogeneous networks. The algorithm incorporates different congestion window settings in the slow start through a threshold and through the size of the receiver notification window by increasing the amount of data transmitted in the slow start to improve the throughput of the satellite link. The algorithm then differentiates packet losses in congestion avoidance through the sizes of unacknowledged data in the heterogeneous network, using different threshold settings for different unacknowledged data sizes. The simulation results show that the proposed algorithm has some advantages over the TCP Hybla, TCP Veno and TCP Reno schemes in terms of the throughput of the satellite link, the download response time of the multihop network and the queue delay of nodes. [ABSTRACT FROM AUTHOR]

The spatial network has numerous nodes and complex links, which makes it more suitable for the Multipath Transmission Control Protocol (MPTCP). As an extension of the traditional TCP protocol, this protocol can aggregate the bandwidth of multiple paths to improve transmission performance. However, the traditional network architecture has limited support for MPTCP, making it impossible to select a good transmission path for the subflow according to the current global network status, so it is easy to cause subflow collision. By separating the control plane and data plane, the Software Defined Network (SDN) architecture can obtain the global network status and better manage the network. The introduction of SDN can solve the problem that traditional networks cannot optimize subflow transmission based on the global network status. However, the existing SDN-based solutions mainly optimize the terrestrial network and take the available bandwidth of the network as the key reference factor, which is not suitable for the network environment with a large scale of time and space such as the spatial network. Besides, due to the high-speed movement of satellite nodes, frequent link switching will cause the selected path to fail and affect the subflow transmission on the path. For this reason, a dynamic subflow allocation strategy for multi-path transmission in SDN-based spatial networks is proposed in this paper, which uses the SDN controller to monitor and analyze the network status, and selects multiple optimal and disjoint transmission paths for the subflow based on the delay and bandwidth of the path to improve the link utilization and load balancing. Then, the strategy uses the predictable characteristics of the spatial network topology to predict the link to be disconnected, reselects the optimal path for the subflow, and solves the problem that the subflow cannot be continuously transmitted due to link switching. The experimental results show that the strategy in this paper is more suitable for the spatial network, because the selected path has lower delay and higher bandwidth. It solves the collision problem of subflows, and makes the subflow transmission have better stability in the highly dynamic spatial network. [ABSTRACT FROM AUTHOR]

Large-scale low earth orbit (LEO) satellite constellation projects are increasingly adopting inter-satellite links (ISLs) to enable their autonomous and collaborative operation. Due to the large number of satellite constellation network nodes and their continuous movement in orbit, the network nodes may not remain visible to each other at all times, so the ISL-building choices among satellites are diverse and vary with time. As a result, maintaining a network topology requires onboard planning and management. In this paper, we creatively propose an onboard centralized ISL-building planning scheme with the goal of autonomous topology management. A multi-antenna visibility calculation method that takes the antenna installation angle and the turntable rotation threshold into account is provided for the visibility calculation procedure. Additionally, the link-building planning process is modeled using integer linear programming (ILP); however, to tackle the computational complexity problem of ILP, a link-building planning method based on topology stability optimization is presented. The simulation results show that the proposed onboard centralized ISL-building planning scheme can operate among satellites to successfully realize network status collection, visibility calculation, link-building planning, and planning result distribution, as conducted by the dynamic primary satellite. Moreover, the inter-plane link-building planning method based on topology stability optimization improves the network topology stability on the basis of reducing the network delay. [ABSTRACT FROM AUTHOR]

Single event upset (SEU) refers to the change in the state of a digital circuit caused by a single, energetic particle passing through the sensitive area of semiconductor components. In the space environment, cosmic rays and high-energy particles may lead to SEUs, which can cause failures of routing functions, such as forwarding errors, in satellite networks. This paper focuses on the impact of SEUs on satellite networks from the perspective of distributed routing. The influence of SEUs on a single satellite can easily spread to the entire satellite network through distributed routing, which can influence the reliability of the satellite network. We propose a framework for the reliability analysis of satellite networks under the impact of SEUs. According to the influence of SEUs on the execution of routing programs in different routing phases, we present the error propagation model of satellite networks for understanding SEUs in satellite network routing. We found that all the influences on program execution ultimately converge on data forwarding and can be reflected in the proposed path topology graph. Therefore, we propose an algorithm that can evaluate the impact of SEUs on satellite networks by analyzing the path topology graphs in both normal and SEU scenarios. The feasibility and effectiveness of the proposed method is demonstrated by experiments. The proposed method could provide a new perspective and theoretical basis for research on secure routing mechanisms and program/instruction reinforcement. [ABSTRACT FROM AUTHOR]

In the space environment, cosmic rays and high-energy particles may cause a single-event upset (SEU) during program execution, and further cause silent data corruption (SDC) errors in program outputs. After extensive research on SEU and SDC errors, it has been found that SDC errors in the routing program in satellite networks may lead to the emergence of Sinkhole (SH) and Grayhole (GH) nodes in the network, which may cause damage to satellite networks. To find and solve the problems in time, a digital-twin-based detection and protection framework for SDC-induced SH and GH nodes in satellite networks is proposed. First, the satellite network fault model under SEU and the generation mechanism of SH and GH nodes induced by SDC errors are described. Then, the data structure based on digital twins required by the proposed detection and protection framework is designed, and the detection methods of SH and GH nodes induced by SDC errors are proposed. SKT and LLFI simulation tools are used to build a simulated Iridium satellite network and carry out fault injection experiments. Experiment results show that the accuracy of the proposed detection method is 98–100%, and the additional time cost of routing convergence caused by the proposed framework is 3.1–28.2%. Compared with existing SH and GH detection methods, the proposed methods can timely and accurately detect faults during the routing update stage.

In recent years, the low-Earth-orbit (LEO) satellite network has achieved considerable development. Moreover, it is necessary to introduce edge computing into LEO networks, which can provide high-quality services, such as worldwide seamless low-delay computation offloading for unmanned aerial vehicles (UAVs) or user terminals and nearby remote-sensing data processing for UAVs or satellites. However, because the computation resource of the satellite is relatively scarce compared to the ground server, it is hard for a single satellite to complete massive deep neural network (DNN) inference tasks in a short time. Consequently, in this paper, we focus on the multi-satellite collaborative inference problem and propose a novel COllaborative INference algorithm for LEO edge computing called COIN-LEO. COIN-LEO manages to split the complete DNN model into several submodels consisting of some consecutive layers and deploy these submodels to several satellites for inference. We innovatively leverage deep reinforcement learning (DRL) to efficiently split the model and use a neural network (NN) to predict the time required for inference tasks of a specific submodel on a specific satellite. By implementing COIN-LEO and evaluating its performance in a highly realistic satellite-network-emulation platform, we find that our COIN-LEO outperforms baseline algorithms in terms of inference throughput, time consumed and network traffic overhead.

Aiming at the problem that the number of users and available bandwidth of the current satellite service are increasing significantly, and the spectrum utilization rate of the existing spectrum allocation scheme is low, this paper first establishes a space-earth integrated spectrum resource sharing model, and analyzes the scenario of using the idle spectrum of the ground network to recognize the satellite downlink. Furthermore, a spectrum allocation algorithm based on stable matching is proposed for cognitive satellite network. According to the transmission characteristics of satellite communication, utility functions of cognitive satellite are given. Users can form stable matching between PUs and SUs through independent negotiation. The spectrum allocation algorithm proposed in this paper has low complexity and can adapt to dynamic networks. Experiments show that the proposed algorithm is superior to greedy matching and random matching in utility value, average sum rate, throughput and spectrum utilization ratio, so as to effectively allocate satellite spectrum.

The Internet of Things (IoT) has influenced technology in numerous ways. What started as a network of physical devices communicating over the Internet grew tremendously sophisticated by incorporating billions of devices and defining specific IoT domains. IoT has found its subdomains in many fields such as medicine, healthcare, robotics, etc., and several domains are yet to incorporate IoT. One of the rapidly advancing technologies in space research. Space research has been growing tremendously over the last few decades, with studies ranging across exoplanet detection, colonization, space communication, and the possibility of life forms across other bodies. In this paper, we suggest a novel architecture of the Internet of Space Things (IoST) compatible with the cloud for the increasingly growing and futuristic field of space technology. The article proposes a detailed physical and logical architecture considering the public network, cloud provider, enterprise network, ground station, and interspace communication. The study will benefit researchers and scientists working in IoT, space technologies, colonization, robot-assisted surgery, space farming, etc.

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