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Low Earth Orbit Satellite Security and Reliability: Issues, Solutions, and the Road Ahead

Pingyue Yue, Jianping An, Jiankang Zhang, Jia Ye, Gaofeng Pan, Shuai Wang, Pei Xiao, Lajos Hanzo

arXiv:2201.03063v3eess.SP

TL;DR

LEO satellite communication systems face both adversarial security attacks and non-adversarial reliability risks, while existing literature provides limited coverage of these issues. This paper reviews their characteristics, requirements, vulnerabilities, enhancement solutions, trade-offs, and future research directions.

  • Problem

    Existing work focuses on security attacks, but LEO SCSs also face reliability risks such as single-event upsets and collisions.

  • Method

    The paper critically reviews LEO SCS characteristics, requirements, security attacks, reliability risks, enhancement solutions, trade-offs, and lessons learned.

  • Results

    The review classifies LEO SCS issues into security attacks and reliability risks and surveys corresponding security and reliability enhancement solutions.

  • Takeaways & Limitations

    Reliable and secure LEO SCS design must address both adversarial threats and operational hazards, including interference, jamming, collisions, and debris.

  • Takeaways & Limitations

    Machine-learning solutions are constrained by the limited public availability of real satellite datasets, leading researchers to use simulated or ground-generated data.

Abstract

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Low Earth Orbit (LEO) satellites undergo a period of rapid development driven by ever-increasing user demands, reduced costs, and technological progress. Since there is a paucity of literature on the security and reliability issues of LEO Satellite Communication Systems (SCSs), we aim to fill this knowledge gap. Specifically, we critically appraise the inherent characteristics of LEO SCSs and elaborate on their security and reliability requirements. In light of this, we further discuss their vulnerabilities, including potential security attacks launched against them and reliability risks, followed by outlining the associated lessons learned. Subsequently, we discuss the corresponding security and reliability enhancement solutions, unveil a range of trade-offs, and summarize the lessons gleaned. Furthermore, we shed light on several promising future research directions for enhancing the security and reliability of LEO SCSs, such as integrated sensing and communication, computer vision aided communications, as well as challenges brought about by mega-constellation and commercialization. Finally, we summarize the lessons inferred and crystallize the take-away messages in our design guidelines.

I. INTRODUCTION

LEO SCSs are expanding because they offer low latency, reduced deployment costs, and broad application potential, but their security and reliability issues remain incompletely covered in existing literature.

  • LEO SCS development: About 7824 LEO satellites were successfully launched from 2012 to the second quarter of 2023, reflecting rapid deployment enabled by reduced launch costs and time.LEO satellites are closer to Earth than MEO and GEO satellites, making them suitable for delay-sensitive communications.
  • Application scenarios: LEO SCSs support remote sensing and access, smart-city services, vehicular communication, telemedicine, and industrial or agricultural monitoring.Applications include mines, farms, mariculture farms, solar power plants, smart factories, homes, and emergency medical services.
  • Security motivation: These applications create security concerns involving confidential sensor data, patient privacy, eavesdropping, and communication disruption from jamming.Dense mega-constellations also make the electromagnetic environment more complex, increasing the risk of disrupted communications.
  • Research gap: Existing studies address selected security topics, integrated networks, or satellite applications, but often omit attacks such as jamming and message modification or LEO-specific reliability issues.Prior work includes physical-layer security, AI, blockchain, cognitive radio, and application-specific defenses, with incomplete coverage across threats.
  • Research gap: This survey critically appraises 23 citations and extends prior work by discussing reliability enhancement solutions alongside security issues and design guidelines.The paper explicitly contrasts its scope with existing magazine and survey papers.
  • Research gap: LEO SCS issues comprise both adversarial security attacks and non-adversarial reliability risks such as single-event upsets and collisions.The literature review identifies limited treatment of physical threats and motivates a broader assessment of LEO SCS issues.

3) Lack of Design Guidelines of Secure and Reliable LEO SCSs:

The paper argues that secure and reliable LEO SCS design requires integrated solutions and explicit guidelines that account for system characteristics, requirements, issues, and trade-offs.

  • Need for design guidelines: Security and reliable operation cannot depend on one solution alone; multiple enhancement solutions must cooperate.The paper links solution design to the relationship among confidentiality, integrity, and latency.
  • Need for design guidelines: LEO satellite constraints on size, memory, and power make complex encryption algorithms unsuitable onboard, requiring trade-offs between satellite and ground-segment capabilities.Ground systems generally have greater power and computing resources, while satellites may lack an operating system or use a stripped-down version.
  • Need for design guidelines: Existing literature does not integrate advanced security and reliability solutions into a unified safeguard for LEO SCSs.This gap motivates design guidelines distilled from system characteristics, requirements, issues, solutions, lessons, and trade-offs.
  • Survey contributions: The survey reviews LEO characteristics and requirements, categorizes security attacks and reliability risks, and analyzes their impacts and lessons.Reliability examples include single-event upsets and collisions with debris.
  • Survey contributions: Security enhancement solutions are organized as active or passive methods for prevention, detection, and mitigation, while reliability enhancement solutions and QoS trade-offs are also discussed.The paper’s organization includes separate sections for active security, passive security, reliability enhancement, and QoS trade-offs.
  • Future directions: The paper covers open problems including integrated sensing and communication, computer-vision-aided space communication, and LEO SCS commercialization.These topics appear in the road-ahead organization alongside design guidelines and concluding remarks.

III. BACKGROUND

The background outlines LEO SCS architecture, constellation development, and the standardization work integrating LEO satellites with terrestrial networks.

  • System architecture: LEO SCSs comprise space, ground, and user segments connected through satellites, gateways, the NCC, links, and user terminals.ISLs may connect satellites, while systems without ISLs require enough gateways for satellite visibility and reliable operation.
  • LEO constellation development: LEO mega-constellations are being redeveloped to provide low-latency services and broader Internet access through advanced materials, technology, and economies of scale.Earlier systems faced high costs, immature technology, and modest communication capabilities.
  • LEO and terrestrial integration: Research and industry are shifting toward LEO-based NTNs to extend 5G services to mMTC devices, especially in remote areas.This shift reflects demand for integrating terrestrial and satellite networks.
  • Standardization progress: 3GPP standardization progressed from Release-15 studies of NTN scenarios and channels to Release-16 and Release-17 work on 5G NR adaptation, architecture, synchronization, and HARQ.Release-17 considered transparent and regenerative architectures and Doppler compensation using UE position and satellite ephemeris.
  • Standardization progress: 3GPP identified NTN use cases including UE access and backhaul, IoT coverage, and mission-critical access during disasters.Subsequent work addressed network functions, mobility management, satellite delay, QoS, core-network architecture, and IoT NTNs.

C. Inherent Characteristics and Unique Challenges

LEO SCSs face security and reliability challenges arising from their orbit, mobility, scale, limited resources, production choices, and differentiated service requirements.

  • Orbit and spectrum: LEO satellites’ position between terrestrial systems and higher orbits increases exposure to low-power jamming and cross-system interference.Spectrum sharing and passage through GEO line-of-sight paths can produce severe CCI.
  • Mobility and orbital environment: High mobility limits satellite visibility time, complicating terminal mobility management and authentication while increasing collision and debris risks.The expanding satellite population and launch activity intensify these reliability threats.
  • Scale: Large numbers of satellites and gateways expand the attack surface required for global coverage.Transparent systems rely on many gateways, whereas onboard-processing systems may rely on multiple interconnected satellites.
  • Resource constraints: Limited power, storage, computation, and satellite mass constrain security processing and reliable operation.Starlink satellites weigh 227 kg and OneWeb satellites less than 150 kg; remote terminals may depend on batteries or solar panels.
  • Production and hardware: Low-cost production increases reliance on civilian-manufactured COTS components, while cosmic radiation can impair FPGA programs and algorithms.These production and radiation exposures affect both security and reliability.
  • QoS requirements: Security and reliability solutions must preserve QoS across differentiated services, including high connection density for mining and highly reliable low-latency telemedicine.QoS indicators include latency, traffic rate, BER, and voice or video quality.

B. Integrity

Integrity in LEO SCSs requires protecting information accuracy and completeness against jamming, mobility-induced Doppler effects, environmental risks, and competing system requirements.

  • Integrity threats: Powerful jamming can contaminate an entire frequency band, while LEO’s proximity to Earth makes such attacks easier than against GEO satellites.DSSS is presented as a countermeasure, while Doppler shift can impair integrity even without jamming.
  • Environmental constraints: LEO mega-constellations contribute to orbital crowding, requiring debris-removal measures to reduce harmful impacts on space operations.Debris from transportation tools and operational or retired satellites increases the problem.
  • Environmental constraints: Spectrum sharing under scarce resources requires LEO SCSs to avoid excessive interference with GEO SCSs.This requirement accompanies the broader integrity and reliability concerns of shared spectral environments.
  • Latency and QoS: End-to-end latency combines propagation, processing, and queuing delays, so security and reliability measures must account for their joint effect.At 600 km altitude, the uplink/downlink turnaround propagation delay is 4 ms, while G.729 adds 10 ms at both encoder and decoder.
  • Trade-offs: Security and reliability requirements cannot generally be optimized simultaneously because improving confidentiality can reduce integrity and increasing integrity can increase eavesdropping probability.The paper frames the design problem as multi-component Pareto optimization over non-dominated operating points.

2) Active Security Attacks:

Active security attacks disrupt or damage LEO SCS operation through jamming, spoofing, message modification, denial of service, node compromise, and node destruction.

  • Jamming attacks: Power-based jamming disrupts reception by transmitting high-power signals, exploiting bent-pipe transponders that lack onboard digital signal processing.Space-, air-, and ground-based jamming differ in range, duration, flexibility, power, and affected transmission direction.
  • Jamming attacks: Spoofing jamming deceives receivers with malicious signals that imitate genuine signal characteristics, requiring knowledge of waveforms and frame structures.It is more technical than power-based jamming.
  • Message modification: Message modification intercepts and changes, inserts, or deletes messages, particularly after attackers obtain ground-segment data-operation permission.Modified messages may lead to wrong decisions.
  • Availability attacks: DoS attacks overwhelm ground or space segments with persistent requests, while forged authentication requests can overload the ground segment.Distributed DoS recruits many compromised IoT devices to attack a target simultaneously.
  • Node attacks: Compromised nodes are difficult to detect because their behavior can resemble legitimate nodes, enabling information leakage and collateral damage.Code patches are identified as a mitigation method.
  • Node attacks: Node destruction threatens satellites, ground segments, and terminals through capture, anti-satellite weapons, missiles, and high-power lasers.Power-limited terminals without advanced protection are especially exposed to adversarial capture.
  • Attack classification: Passive attacks primarily steal confidential information, whereas active attacks target integrity and availability and may exploit information obtained passively.Active attacks can cause severe collateral damage when hostile nodes impersonate legitimate ones and consume resources.
  • Reliability risks: Reliability risks accompany attacks and include intra-system interference, cross-system CCI, SEUs, and collisions.Intra-system interference can arise from waveform selection and scarce spectrum.

2) CCI between Systems:

LEO systems face growing coexistence, radiation, and collision risks as spectrum use and orbital congestion increase. These risks constrain capacity, hardware reliability, and safe operation.

  • 2) CCI between Systems:: Spectrum sharing between LEO, GEO, and terrestrial systems creates CCI under limited radio-spectrum availability.GEO and terrestrial systems have higher priority access, leaving LEO systems to mitigate interference.
  • 2) CCI between Systems:: LEO satellite proliferation increases the probability of CCI, while terrestrial-network convergence makes coexistence planning more complex.The paper identifies this as an ongoing concern for future ubiquitous connectivity.
  • Reliability risks: Below 2000 km, higher orbit altitude and inclination nearer 90° increase the probability of single-event upsets.SEUs are reversible soft errors because rewriting or resetting can restore the circuit state.
  • Reliability risks: LEO orbits between 800 and 1400 km are especially crowded, increasing collision risks for satellites and spacecraft.Miniaturized satellites and mega-constellations contribute to this concentration.
  • Reliability risks: Collision hazards include spacecraft impacts and debris, with ESA estimating approximately 1036500 debris objects larger than 1 cm in orbit.Reported incidents include damage to Hubble, Endeavour, and Sentinel-1A, while operators plan avoidance maneuvers when risk exceeds a threshold.
  • Lessons Learned: Reliable LEO operation requires orbit selection, but satellite resource limits and operational difficulty constrain high-complexity security enhancements.FPGAs offer flexibility but require measures such as TMR and periodic refreshing to address SEUs.

VI. SECURITY AND RELIABILITY ENHANCEMENT SOLUTIONS

The paper organizes enhancement measures around prevention, detection, and mitigation, and further distinguishes active from passive solutions. It surveys cryptographic, communication, and learning-based approaches alongside their deployment constraints.

  • VI. SECURITY AND RELIABILITY ENHANCEMENT SOLUTIONS: Prevention, detection, and mitigation form the core principles for security and reliability enhancement in LEO SCSs.Prevention acts before exposure, detection identifies bypassed attacks, and mitigation limits damage after issues occur.
  • VI. SECURITY AND RELIABILITY ENHANCEMENT SOLUTIONS: Active solutions provide prevention or detection, whereas passive solutions directly confront issues and reduce or eliminate their impacts.The paper classifies the solution landscape accordingly in Fig. 12.
  • Active Security Enhancement Solutions: QKD, blockchain, THz, space-based laser communications, and AI support active prevention or detection of impending security and reliability issues.The approaches target information-theoretic security, decentralization, spectrum-crunch interference, traffic prediction, telemetry mining, and anomaly detection.
  • 1) Quantum Key Distribution:: Quantum communication research includes free-space experiments and satellite-based QKD, but large-scale deployment remains an open challenge.The paper notes the first quantum satellite-based QKD experiment in 2016 and continuing service efforts by ESA and Canada.
  • 1) Quantum Key Distribution:: QKD faces limited distance, cloud-induced optical attenuation and scattering, telescope-alignment requirements, and additional challenges from LEO mobility.Operational QKD networks generally provide point-to-point or short-distance key distribution because quantum signals cannot be amplified.

2) Blockchain:

Blockchain offers decentralized, tamper-resistant management for growing LEO networks, while THz and laser links address spectrum scarcity and interference. These technologies remain constrained by resource, propagation, alignment, and mobility challenges.

  • 2) Blockchain:: Blockchain stores transactional records across peer-to-peer nodes, making it a candidate for decentralized LEO SCS management.Its use is motivated by increasing numbers of satellites and supported users.
  • 2) Blockchain:: Encrypted records, immutable updates, and distributed replication support confidentiality, accountability, decentralization, and fault tolerance.Other nodes can retain data and continue functioning when one or more blockchain nodes fail.
  • 2) Blockchain:: Blockchain-based schemes have been applied to spoofing-jamming detection, modification protection, DDoS identification, and false-report filtering.Some filtering schemes reduce key-storage and communication overhead by avoiding critical exchanges between sensor nodes.
  • 2) Blockchain:: Blockchain security services require substantial storage and computing power, creating challenges for resource-constrained terminals and LEO satellites.Sharing sensitive information among gateways or satellites also requires explicit privacy protection.
  • 3) THz and Space-based Laser Communication:: THz and optical bands offer additional spectrum, but THz transmission distance and propagation loss limit satellite applications.The paper notes 21 km at 140 GHz as insufficient for inter-satellite links and calls for larger antenna arrays and higher-power devices.
  • 3) THz and Space-based Laser Communication:: Laser communications provide strong anti-interference capability and favorable size, weight, and power characteristics, but directional beams complicate alignment in mobile LEO links.High velocity, payload jitter, and Doppler shifts make inter-satellite acquisition, tracking, and synchronization difficult.

4) Aritificial Intelligence:

AI and ML support prediction, anomaly detection, classification, and attack analysis across LEO satellite data. Their practical use is limited by computational burden and scarce real-satellite datasets.

  • 4) Aritificial Intelligence:: ML learns empirical models and tracks changing data patterns, supporting security analysis across diverse satellite data types.Neural networks, including LSTM and GRU, are prominent techniques for prediction, anomaly detection, and classification.
  • Tele-traffic Data: Traffic prediction can optimize routing and resource scheduling, mitigate CCI, reduce outages and congestion, and support early abnormal-traffic detection.GRU reduces gate complexity relative to LSTM and can combine transfer learning with online training.
  • Housekeeping Data: LSTM achieves the highest prediction accuracy for evaluated battery-temperature, power-bus-voltage, and load-current data, while GRU has the shortest running time.Temporal convolution networks are also noted for parallel processing and operational efficiency compared with LSTM.
  • Spectrum Data: ML processes spectrum features such as interference type, bandwidth, intensity, and frequency for interference classification and management.Experiments demonstrated nearly 100% accuracy in spectrum detection across six interference patterns.
  • Data limitations: Real-satellite datasets are rarely public, so studies often use simulated, ground-generated, or internet network-traffic data instead.Dataset availability is identified as a key implementation bottleneck.
  • Passive Security Enhancement Solutions: Passive AI-oriented solutions complement antennas and coordination techniques for mitigating eavesdropping, CCI between systems, and malicious power-based jamming.The paper also discusses AI tools alongside security-oriented antennas and other passive measures.

2) Reconfigurable Intelligent Surfaces:

RIS-based techniques can enhance secrecy and interference management in LEO SCSs, but their effectiveness depends on deployment conditions, satellite dynamics, and computationally difficult optimization.

  • RIS fundamentals: RISs manipulate reflecting-element phase and amplitude to improve the wireless environment, mitigate line-of-sight blockage, and support secure communications.Passive RISs alter propagation without active amplification, while active RISs add power consumption and thermal noise.
  • Security enhancement: RIS-assisted security schemes jointly design terrestrial beamformer weights and RIS reflection coefficients to reflect interference toward ground eavesdroppers.A HAP-mounted RIS can secure an LEO-to-UAV link even without eavesdropper channel-state information by increasing the number of reflecting elements.
  • Security enhancement: Active RISs can outperform passive RISs in secrecy energy efficiency, but whether they improve security remains an open question.Active RISs consume additional power and amplify thermal noise alongside incident signals.
  • Interference mitigation: RIS performance for interference mitigation improves with more RISs, more reflecting elements, and finer phase-shift resolution.The reported benefit is expressed through improved received SINR and sum rate in LEO and spectrum-sharing networks.
  • Lessons learned: LEO-specific RIS designs must account for limited visibility, frequent handovers, high Doppler shifts, and time-varying SNR, delay, and propagation conditions.Much prior RIS literature targets GEO satellites or omits satellite type, leaving these LEO effects insufficiently investigated.
  • Interference coordination: Interference coordination addresses LEO–GEO coexistence through power control, beam drifting, cognitive radio, and optimization under GEO frequency-priority constraints.Power control must protect GEO users while also affecting LEO throughput; beam drifting can move users into adjacent beams before interference occurs.

4) SS Techniques:

Spread-spectrum and adaptive filtering methods improve confidentiality, integrity, and anti-jamming performance in LEO SCSs, but they expose trade-offs involving throughput, SNR, and implementation complexity.

  • SS techniques: DSSS reduces eavesdropping risk and provides partial jamming immunity, but stronger anti-jamming protection requires longer spreading sequences and lowers payload rate.The payload rate is governed by bandwidth divided by spreading factor, creating a direct throughput-versus-anti-jamming trade-off.
  • SS techniques: FHSS avoids severely jammed frequencies through adaptive hopping, while FFHSS strengthens anti-jamming capability by completing multiple hops within one symbol.Low-complexity non-coherent FFHSS demodulation incurs substantial SNR loss.
  • SS techniques: MC-DSSS senses occupied and available bands, allocating sub-carriers to avoid existing signals and improve signal integrity.In simulation, BER degraded as concealed frequency-band fraction increased from 12.5% to 50%.
  • Jamming suppression: When jamming exceeds an SS receiver’s tolerance, dedicated suppression methods are required, including temporal LMS filtering and transform-domain filtering.LMS updates weights using current error, whereas transform-domain filtering identifies jamming in frequency space and band-pass filters it before inverse transformation.
  • Satellite cooperation: A single resource-limited LEO satellite may struggle to satisfy confidentiality and integrity simultaneously because lower transmit power improves confidentiality but weakens link integrity.Increasing transmit power reverses this balance by improving legitimate-link integrity while increasing eavesdropping probability.
  • Satellite cooperation: Combining signals from multiple visible satellites can preserve integrity at lower terminal transmit power, provided delay, Doppler, and phase offsets are compensated.A modified SUMPLE algorithm estimates and compensates phase offsets for coherent DSSS combining across satellites.
  • Satellite cooperation: At least 3 satellites mitigated jamming effects in reported experiments, demonstrating cooperation diversity against jamming.The associated scheme jointly optimized terminal transmit power across user–satellite links to maximize total data rate.

7) Artificial Intelligence:

AI supports security and reliability in LEO SCSs by predicting traffic, solving difficult optimization problems, and assisting space-environment monitoring, while practical deployment remains data-constrained.

  • Artificial Intelligence: Deep reinforcement learning combined with simulated annealing addresses dynamic beam hopping under fluctuating traffic demand and time-varying channel conditions.An intelligent method also estimates received signal strengths in overlapping areas to prevent adjacent beams from using identical frequency resources.
  • Artificial Intelligence: Graph attention networks solve RIS passive-beamforming sum-rate problems with low online complexity while capturing dynamic RIS-assisted LEO network topology.Deep learning has also been used to optimize RIS coefficients for secrecy-related objectives.
  • Artificial Intelligence: AI can predict traffic features and evolutionary trends, helping avoid future congestion and high co-channel interference.The paper positions AI as useful across active and passive information-domain safeguards.
  • Lessons learned: AI-based security and reliability methods depend on sufficiently large training datasets, which may be inaccessible in practical LEO SCS deployments.This data requirement is identified as a condition for successful AI application.
  • Reliability enhancement: Reliability enhancement combines SSA, debris removal, radiation resistance, and sensor-based debris tracking to support stable satellite operation.SSA uses ground- and space-based facilities and algorithms to detect and track resident space objects.
  • Lessons learned: Crowded mega-constellation orbits, debris generation, and cosmic radiation increase collision and electronic-device failure risks, while spaceborne THz systems remain power-limited.THz systems may support secure inter-satellite links and debris detection, but their attainable transmission power limits communication distance.

2) Debris Removal:

LEO debris threatens satellite reliability through collision cascades, motivating detection, avoidance, removal, and coordinated international action. Existing removal options span nets, harpoons, lasers, robotic arms, balloons, and suicide satellites, but remain largely experimental.

  • Debris Removal:: LEO is heavily contaminated by debris, creating substantial collision risk and potentially triggering avalanche-like chains of further collisions.Debris arises from explosions, impacts, and launch activities, while mega-constellations increase the number of high-speed objects.
  • Debris Removal:: Removal concepts include nets, harpoons, lasers, robotic arms, giant balloons, and low-cost suicide satellites that de-orbit debris.These methods capture, redirect, slow, or increase the atmospheric drag of debris or failed spacecraft.
  • Debris Removal:: The RemoveDEBRIS mission verified the feasibility of capturing a nearby released target probe with a net.The capture occurred on September 16th, 2018.
  • Debris Removal:: Removal techniques remain in the design or experimental phase, requiring further engineering and operational validation under time-varying space conditions.Practical feasibility must be verified before action because environmental uncertainties affect target identification and removal decisions.
  • Debris Removal:: Reducing debris risk requires countries and research institutions to share responsibilities, establish cooperation mechanisms, and prevent new debris while removing existing debris.Recommended measures include safe end-of-life disposal and robotic arms, balloons, nets, or harpoons for large debris.
  • Debris Removal:: AI, sensors, radar, optical telescopes, and filtering algorithms support debris detection, tracking, collision avoidance, identification, and removal planning.Deep learning addresses low-SNR debris detection, while reinforcement learning supports online reactive removal planning.

4) Radiation Resistance:

Radiation resistance combines hardware selection, redundancy, refreshing, and targeted protection to maintain reliable payload operation in harsh space environments. The central design trade-off is between reliability or integrity and resource, computation, bandwidth, or implementation overhead.

  • Radiation Resistance:: Radiation resistance uses advanced chips and redundancy, assigning time-invariant functions to ASICs and upgradeable programs to flexible FPGAs.The formulation of radiation-resistance measures follows the process illustrated in Fig. 22.
  • Radiation Resistance:: Triple Modular Redundancy masks single-event upsets by voting among three identical program modules, but consumes three times the original module’s resources.Designers therefore commonly apply TMR selectively to key program components such as control logic.
  • Radiation Resistance:: Periodical refreshing corrects errors without interrupting execution, but FPGA block RAM loses its real-time state during refresh and therefore also needs TMR.Refreshing does not cover every FPGA resource.
  • Radiation Resistance:: Combining partial TMR with periodical refreshing may improve FPGA reliability by balancing SEU mitigation against resource consumption and coverage limitations.TMR detects and corrects SEU effects, whereas refreshing avoids additional resource consumption but cannot protect all FPGA resources.
  • Trade-offs in Quality of Service (QoS) guarantees:: LEO security and reliability solutions require segment-specific choices because improvement must be weighed against overhead and satellites’ limited computation capabilities.Computationally intensive encryption may be unsuitable for satellites but routinely used in ground segments.
  • Trade-offs in Quality of Service (QoS) guarantees:: DSSS, MC-DSSS, and adaptive filtering expose trade-offs among integrity, confidentiality, anti-jamming capability, convergence speed, latency, and weight variance.For temporal-domain LMS filtering, a higher step size accelerates convergence but increases weight variance.

C. Mega-Consetellations

Mega-constellations intensify operational, networking, standardization, security, and commercial challenges as LEO systems scale. The paper responds with design guidance grounded in reliability, security, and resource considerations.

  • Scale and operations: Mega-constellation operators must supervise hundreds or thousands of satellites in real time, making minor computational or command errors potentially severe.
  • Scale and operations: Inter-satellite links reduce ground-station and relay-satellite deployment costs but create multi-hop networking challenges.
  • Commercialization: Commercial growth intensifies competition and makes uniform satellite and product quality difficult to maintain as more partners enter the industry.
  • Commercialization: Commercialization expands LEO applications but increases security challenges because diverse terminals, standards, and operational policies are more prone to attackers.
  • Design implications: Secure and reliable design must balance conflicting factors, begin from security specifications, and use lightweight, low-power solutions on resource-limited satellites.
  • Design implications: Orbit, frequency, and waveform choices must jointly address collision avoidance, single-event upsets, interference, and application-specific resource constraints.

E. LEO SCSs Secure and Reliable Design

Secure and reliable LEO SCS design combines protections across antennas, processors, ground segments, users, and collision-management systems. The paper frames these measures around both security attacks and reliability risks affecting safe operation.

  • Security enhancement: Security-oriented antennas, artificial noise, RISs, and satellite cooperation can mitigate eavesdropping and jamming while preserving signal integrity and reducing terminal transmit power.
  • Reliability enhancement: Radiation-resistant processors are required because single-event upsets threaten the reliable operation of onboard programs and algorithms.
  • Security enhancement: Ground segments support complex encryption, machine learning, and blockchain because they provide operation and control with abundant power, but malfunctions can halt the system.
  • Security enhancement: Users should update patches regularly and cooperate with the space segment through frequency or transmit-power adjustments to reduce attacks and intra-system interference.
  • Reliability enhancement: Collision reliability requires ground monitoring and advance warning, plus onboard SBRs or SBCs that detect erratic debris movement and enable immediate satellite adjustment.
  • Reliability enhancement: LEO systems must limit interference with GEO systems through coordinated uplink power control and beam drifting before interference occurs.
  • Scope: The paper identifies eavesdropping, DoS, collisions, and SEUs as security and reliability challenges, then organizes solutions, trade-offs, lessons, future directions, and design guidelines.
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