Satellite Computing Network Construction: Optimal Computing Node Deployment in Multi-layer LEO Mega-constellations

Low Earth Orbit (LEO) satellite communication systems have evolved into a critical component of global broadband networks, enabling wide‐area connectivity, IoT services, and intelligent multilayer satellite–terrestrial integration. Despite rapid advancements in constellation deployment, routing mechanisms, resource management, and LEO–5G/6G convergence, the long‐term evolution of research themes and network architectures remains insufficiently mapped. This study analyzes 2420 Web of Science articles published between 1995 and 2025 and applies bibliometric techniques, main path analysis, and edge‐betweenness clustering to identify the core technological trajectories shaping the LEO communication domain. The results reveal five major phases of development: foundational constellation design, multilayer architecture integration, performance and QoS optimization, 6G‐driven intelligent connectivity, and secure collaborative networking. Four dominant research clusters emerge: communication and IoT applications, routing and topology management, satellite edge computing and task offloading, and LEO‐enhanced GNSS positioning, highlighting the field's structural diversification. Main path and key‐route analyses further show a gradual shift from traditional connectivity‐oriented engineering toward distributed, AI‐enabled, and security‐aware satellite communication frameworks. This study provides the first longitudinal mapping of LEO communication research, offering an integrated understanding of how architectural evolution, protocol innovation, and emerging intelligent services intersect. The findings support future advances in satellite networking, resource optimization, and the design of resilient and interoperable LEO systems.

With the emergence of cellular radio technology, there has been a renewal of interest in low-Earth orbit (LEO) satellite communication networks. Interest in these type of systems is fuelled by reduced propagation delays compared to those experienced by geostationary satellites as well as the benefits associated with mobile and tetherless communications. LEO systems are presently being proposed to provide global communications for both voice and data applications. These systems are being designed to provide communications to areas of the world where either public telephone systems do not exist or cannot be provided due to terrain constraints. This paper examines the effects of packet-switched low-Earth orbit satellite systems as a medium for wireless communications. An overview of LEO systems is provided, as well as critical issues associated with the implementation of such a system. The benefits as well as the detriments to the implementation of LEO systems over other types of communication networks are addressed. To illustrate the nature of LEO communications, six representative constellations, varying in size from 36 to 77 satellites and residing at orbital altitudes ranging from 765 to 1549 kilometers, are examined.

Low Earth Orbit (LEO) satellite communication networks have become an important means to provide internet access services for areas with limited infrastructure. Compared with the Geostationary Earth Orbit (GEO) satellites, the LEO satellites have limited on-board communication caching and calculating resources. Furthermore, the distribution of traffic requests is dynamically changing and uneven due to the relative movement between the LEO satellites and the ground. Therefore, how to schedule the multi-dimensional resources is an important issue for the LEO satellite communication networks. Beam-hopping is an efficient approach to improve the resource utilization by dynamically allocating time, power, and frequency according to the traffic requests. This paper proposes an efficient multi-dimensional resource allocation mechanism for beam-hopping in LEO satellite networks, which simultaneously satisfies the GEO interference avoidance. First, we construct the beam-hopping model of LEO satellites, and formulate the resource optimization problem. Second, we provide the weighted greedy strategy to determine the illumination pattern. In order to reduce the search space, the cells are clustered to non-interference clusters. Then, an improved genetic algorithm is provided to jointly allocate the communication resources. Finally, we construct various simulations to evaluate our proposed mechanism. Compared with the random-BH, polling-BH and traditional genetic algorithm, our algorithm achieves better performance in terms of both system throughput, access success rate, average delay and fairness between cells. The performance improvement is more significant in scenarios where traffic demand is unevenly distributed.

Low earth orbit (LEO) satellite communications are expected to be incorporated in future wireless networks to provide global wireless access with enhanced data rates. Massive multiple-input multiple-output (MIMO) techniques, though widely used in terrestrial communication systems, have not been applied to LEO satellite communication systems. In this paper, we propose a massive MIMO downlink (DL) transmission scheme with full frequency reuse (FFR) for LEO satellite communication systems by exploiting statistical channel state information (sCSI) at the transmitter. We first establish a massive MIMO channel model for LEO satellite communications and propose Doppler and time delay compensation techniques at user terminals (UTs). Then, we develop a closed-form low-complexity sCSI based DL precoder by maximizing the average signal-to-leakage-plus-noise ratio (ASLNR). Motivated by the DL ASLNR upper bound, we further propose a space angle based user grouping algorithm to schedule the served UTs into different groups, where each group of UTs use the same time and frequency resource. Numerical results demonstrate that the proposed massive MIMO transmission scheme with FFR significantly enhances the data rate of LEO satellite communication systems.

In this paper, we consider the sparse code multiple access (SCMA) for low earth orbit (LEO) satellite communications to achieve high user capacity and provide technical support for satellite-based Internet of Things (IoT) applications. Note that Doppler shift in the LEO satellite link can not be ignored and the message passing algorithm (MPA) extensively utilized by SCMA is quite time-consuming due to high complexity. Thus we propose a coherent iterative receiver with low complexity for SCMA-based LEO satellite communication systems. First, we design a data-aided carrier synchronization scheme using multiple disjoint pilot blocks to estimate the Doppler shift precisely. Then, a soft-out approximate message passing (SO-AMP) algorithm with linear complexity is derived from the first-order approximation of MPA based on a novel framework of SCMA mapper. Further, a damping method is introduced into the SO-AMP detector developing a damped SO-AMP (DSO- AMP) to improve the overall performance. Numerical results show that the designed receiver can achieve excellent performance close to ideal performance with no Doppler shift while maintaining low complexity.

This work develops an analytical framework for downlink low Earth orbit (LEO) or medium Earth orbit (MEO) satellite communications, leveraging tools from stochastic geometry. We propose a tractable approach to the analysis of such satellite communication systems, accounting for the fact that satellites are located on circular orbits. We accurately incorporate this geometric property of LEO or MEO satellite constellations by developing a Cox point process model that jointly produces orbits and satellites on these orbits. Our work contrasts with previous modeling studies that presumed satellite locations to be entirely random, thereby overlooking the fundamental fact that satellites are jointly positioned on orbits. Employing this Cox model, we analyze the network performance experienced by users located on Earth. Specifically, we evaluate the no-satellite probability of the proposed network and the Laplace transform of the interference created by such a network. Using it, we compute its SIR (signalto-interference) distribution, namely its coverage probability. By presenting fundamental network performance as functions of key parameters, this model allows one to assess the statistical properties of downlink LEO or MEO satellite communications and can thus be used as a system-level design tool to operate and optimize forthcoming complex LEO or MEO satellite networks.

A hybrid multibeamforming receiver for low Earth orbit (LEO) satellite communication in the Ku-band is designed and tested. The proposed receiver is implemented with eight channels to enable multibeam control. The proposed receiver, including both analog and digital beamforming structures, is capable of multibeam reception using both analog and digital beamforming techniques simultaneously or selectively. Analog beamforming is implemented by employing a local oscillator phase shifter using direct digital synthesis and phase-locked loop (PLL) structures. In digital beamforming, a software-defined radio can control the phase of the signal in the digital baseband. The multibeam received using the proposed hybrid multibeamforming receiver was measured at 11.7 GHz and 12.7 GHz in an anechoic chamber. The phase-control resolutions of analog and digital beamforming were 0.022° and 0.72°, respectively. Analog beam-switching speed is slower than digital beamforming because it depends on the settling time of the PLL circuit, but it has a high phase-control resolution. Therefore, by using analog and digital beamforming when precise beam tilting and fast beam switching are required, respectively, the proposed hybrid multibeamforming is shown to be suitable in accordance with the communication situation.

International organizations such as the 3rd Generation Partnership Project (3GPP) and the International Telecommunication Union (ITU) regard non-terrestrial networks (NTNs) as an essential component of the sixth-generation (6G) mobile communication technology and have advanced relevant standardization efforts. Low Earth orbit (LEO) satellite communication (SatCom) constitutes a key part of NTNs, and efficient uplink random access (RA) is crucial for establishing initial connections in LEO SatCom systems. However, the long propagation delay and wide coverage of LEO satellites substantially increase access latency and collision probability due to the limited number of beams and their constrained coverage areas. In addition, the highly non-uniform spatial distribution of user equipment (UE) further aggravates access inefficiency. To this end, this paper investigates joint beam position grouping and RA channel (RACH) occasions (ROs) allocation (JBPGRA) for LEO SatCom systems. Specifically, we develop a system model for RA under beam hopping and identify the key factors that influence RA performance. Furthermore, we derive expressions for both the instantaneous signal-to-interference-plus-noise ratio (SINR) and the average SINR under a given non-uniform UE spatial distribution. Building on this analysis, the JBPGRA problem is formulated as an integer linear programming problem that seeks to maximize RA success while conserving RO resources under non-uniform UE distribution. To achieve a practical solution, we propose an efficient JBPGRA algorithm composed of beam position classification, sparse beam position grouping, and RO allocation modules. Simulation results demonstrate that, under the same UE density, the proposed JBPGRA scheme achieves over 29% higher access success rate in dense beam positions compared with the uniform baseline adopted in existing SatCom systems, while reducing RO consumption by more than 49% and decreasing the number of beam position groups by over 57%.

There is a growing interest in using networks of small satellites in low Earth orbit (LEO) to provide a variety of communications services in conjunction with small ground terminals. The only ’little LEO’ microsatellite digital store‐and‐forward communications network (HealthNet) in commercial operation at the time of writing uses microsatellites, communications payloads, and protocols designed and built at the University of Surrey, U.K. In order to provide an in‐orbit research test‐bed for improving communications with microsatellites in LEO by optimizing modulation and demodulation techniques, an advanced DSP payload, the digital signal processing experiment (DSPE), was included on board the latest Surrey microsatellite (PoSAT‐1). In‐orbit experiments using the PoSAT‐1 DSPE first optimized the existing non‐coherent CPFSK communication systems and then investigated the use of coherent MSK to provide a potential 3dB advantage while remaining compatible with the spacecraft systems. A novel DSP implementation of the Hodgart‐Massey coherent MSK demodulator/decoder was developed by the authors and its behaviour compared with the classical de Buda demodulator undertypical LEO conditions through a sequence of rigorous computer simulations and laboratory bench tests. The simulations and bench tests quantified a practical 2dB improvement in BER performance when compared with non‐coherent CPFSK, while also exhibiting considerable tolerance to the frequency and amplitude variations which are encountered in an LEO environment. These characteristics were subsequently confirmed by in‐orbit demonstrations using the PoSAT‐1 DSPE. The microsatellite, payload, modems and experimental results are presented in this paper and discussed with a view towards implementing an adaptable DSP‐based communications system capable of optimizing data throughput with LEO microsatellites.

Thanks to its long-range, low-power characteristics, the LoRa modulation technique is being increasingly adopted for Low Earth Orbit (LEO) satellite communications with the Internet of Things (IoT) remote node terminals. However, with satellites reaching speeds of around $7.8 \mathrm{~km} / \mathrm{s}$, the LoRa symbols experience a frequency shift due to the Doppler effect which could result in packet loss. This study examines three linear models for evaluating the accumulated Doppler effect in a sequence of LoRa symbols, with a focus on higher spreading factors. The results demonstrate the maximum number of successfully received symbols without error caused by the cumulative Doppler shift per packet for different LoRa configurations, providing initial metrics for mitigation techniques and emphasizing the need for careful consideration of packet length in this communication scenario. Additionally, it was found that the difference in the predicted position of the first error symbol due to accumulated Doppler shift among the three models does not exceed one symbol unity.

Cognitive radio (CR) is an efficient way to increase spectrum efficiency for the small low earth orbit (LEO) satellite communication system. Due to the implementation difficulties, we focus on the CR in the uplink transmission. In CR, the cognitive medium access (CMA) is designed to enable the coexistence with the interferences from other systems. However, the CMA schemes designed for the terrestrial system cannot deal well with the global history of interferences in our system. Here, we design the memorized centroid bucket (MCB) scheme that can efficiently utilize the global history of interferences onboard without storing the complete interference samples. With MCB, we can achieve the effective long-term interference prediction to meet the special requirements of the LEO satellite. The key component in MCB is the matching algorithm that can help retrieve the useful historical information. In this paper, we propose three different matching algorithms and the corresponding MCB schemes. The schemes are also compared with the widely used Markovian method and the pair counting-based method. Among all the schemes, the Bayesian scheme MCB-FSNMI-Bayes is the best. The conclusion is validated experimentally with the real data that were collected by an LEO satellite.

Robust Connectivity in Time-Frequency Dual Fading Channels for the 6G Satellite IoT: Chirp and FRFT

Low Earth Orbit (LEO) satellite communication systems have emerged as a critical solution to address the growing demand for global, seamless, and low-latency connectivity. Compared with Geosynchronous Earth Orbit (GEO) satellites, LEO satellites enable reduced signal delays and broad coverage. Therefore, they are particularly suitable for remote and underserved regions. This paper provides a comprehensive review of LEO satellite communication systems, focusing on three major aspects: frequency band division, system architecture, and case analysis. The study explores the utilization of various frequency bands, including L, S, C, X, Ku, Ka, Q, and V bands, highlighting their characteristics and applications. The system architecture, including the space, user, and ground segments, is analyzed in detail. Additionally, the paper examines the Starlink constellation as a typical example and discusses its architecture, performance, and coverage capabilities. However, LEO satellite communication systems face significant challenges, such as limited resources, high costs, and problems due to the high speed of satellites. Therefore, advancements in artificial intelligence, ultra-narrow beamforming, and 5G and 6G networks present promising opportunities for future development.

This paper extends previous research efforts related to the simulation performance modelling and analysis of satellite communication networks. Specifically, the use of low earth orbit (LEO) satellite networks for personal communications is examined. Six different satellite constellation configurations are investigated in a packet-switched operating environment. Performance metrics examined are the end-to-end packet delay and the utilization of satellite channels in the dynamic environment. Realistic and accurate models of the physical satellite network and its terrestrial transmitters require that numerous operating characteristics and assumptions be specified. These are based on proposed design requirements of commercial systems, such as Iridium. Via the use of simulation, we show the relative delay and utilization performance of differing satellite network architectures. From these simulation models, mathematical metamodels are derived for the system delays. These innovative models are used to predict the delay performance of different network architectures not previously simulated. Comparison of these metamodels with simulation results show that metamodels provide an accurate means for performance prediction. Copyright © 1999 John Wiley & Sons, Ltd.

With the advancement of low earth orbit (LEO) satellite communications, direct-to-satellite technology has attracted widespread attention. Due to the constrained onboard resources of LEO satellite, an efficient resource allocation strategy is essential to meet diverse user traffic demands. Furthermore, the spectrum sharing among multi-layer LEO satellites requires effective interference avoidance mechanism to enhance the overall service quality of the satellite system. To achieve efficient resource management in a dual-layer LEO satellite system, we propose a resource allocation strategy based on multi-agent proximal policy optimization (MAPPO). This strategy consists of three steps. Firstly, beam hopping time plan (BHTP) is designed based on a low complexity strategy. Next, the users served in each time slot are selected according to the buffer status. Finally, the MAPPO framework is employed to enable the flexible allocation of bandwidth and power resources. Simulation results demonstrate that the proposed strategy not only satisfies the diverse traffic demands of terminal users but also effectively reduces satellite power consumption.