Wiley: International Journal of Satellite Communications and Networking: Table of Contents

From an Enhanced TCP to a Multi‐Stream TCP for GEO Satellite Return Links

Zixuan Yu, Hongdong Wang, Furong Guo, Cao Huang — Sun, 07 Jun 2026 22:50:48 -0700

ABSTRACT

To address the severe performance degradation of TCP caused by high latency, time-varying link capacity, and high error rates in the return links of geostationary Earth orbit (GEO) satellite networks, this paper proposes two improvement schemes: TCP-GEO and Multi-stream TCP. TCP-GEO designs an adaptive startup mechanism and adjusts congestion thresholds and window growth strategies dynamically by incorporating the terminal-side information—the allocated bandwidth and the number of concurrent TCP flows. To further address multi-flow contention for the terminal's bottleneck bandwidth, Multi-stream TCP adopts a centralized coordination architecture entity, which constructs an initial window allocation model sensitive to these two terminal-side information, and introduces a joint link state discrimination mechanism using cross-flow correlation to precisely distinguish packet loss caused by terrestrial network congestion and by channel fading, and implements a hierarchical bandwidth allocation policy based on service priority to support differentiated quality of service (QoS). Simulation experiments based on the Satellite Network Simulator 3 demonstrate that TCP-GEO significantly improves bandwidth utilization and fairness. Multi-stream TCP further betters these performance metrics through centralized multi-stream coordination and guarantees transmission rates for high-priority services, making it most suitable for complex environmental scenarios with the bandwidth bottleneck at the terminal.

Geometric Characterization of LEO–GEO Inter‐Satellite Links for Bidirectional Communications

Muhammad Furqan, Lingfeng Ye, Yanming Feng — Thu, 04 Jun 2026 06:54:33 -0700

ABSTRACT

Incorporating geosynchronous Earth orbit (GEO) and low Earth orbit (LEO) satellites can extend communication services far beyond the reach of terrestrial infrastructure. A key enabler of such architectures is the establishment of inter-satellite links (ISLs) between LEOs and GEOs to support bidirectional communications. However, existing research has placed limited emphasis on the inherently dynamic and asymmetric nature of the LEO–GEO connectivity. This study presents a comprehensive numerical analysis of LEO–GEO ISL geometric characteristics, incorporating geometric visibility and pointing constraints, and evaluating link-availability performance and timeline dynamics across a wide range of constellation configurations. The analysis evaluates ISL availability and temporal dynamics using a dual approach: (i) simulations of operational constellations (Iridium, Starlink, and OneWeb) and (ii) a large-scale geometric performance assessment of a wide variety of synthetic orbital shells spanning diverse altitude–inclination combinations. Numerical results show that inclination is the primary driver of LEO–GEO ISL availability, whereas altitude plays a secondary role except beyond a critical height of about 950 km, where GEO field-of-view (FOV) constraints rapidly erode downlink opportunities. Two-GEO configurations generally provide near-continuous downlink for non-FOV-limited constellations (e.g., Iridium and Starlink), with a third GEO offering diminishing, mostly uplink-centric gains. In contrast, FOV-limited systems (OneWeb-like or high-inclination shells) require additional GEO diversity to achieve high downlink availability and to extend contact-arc durations. Low-inclination LEO constellations yield higher uplink availability, whereas higher inclinations reduce uplink opportunities. Overall, these results highlight the need for tightly integrated orbital and link-layer design to fully exploit LEO–GEO ISLs in future space-based communication systems.

Analysis of Multislot Spread Spectrum ALOHA for Satellite Short‐Burst Communication

Liu Tianli, Yang Xuan, Liu Xiaoxu — Tue, 02 Jun 2026 20:24:41 -0700

ABSTRACT

Satellite short-burst communication is a key complement to terrestrial networks in maritime, mountainous, and emergency scenarios. In existing satellite random access systems, Pure Spread Spectrum ALOHA (Pure SSA) is simple to implement but suffers from low resource utilization, whereas ideal Slotted Spread Spectrum ALOHA (Slotted SSA) improves throughput at the cost of forcing large numbers of terminals to start transmission at the same instant, which increases receiver-side signal discrimination and code-allocation pressure under massive access. To bridge these two operating extremes, this paper studies a Multislot Spread Spectrum ALOHA (Multislot SSA) protocol based on cross-microslot transmission. The packet start time is constrained to microslot boundaries, whereas each packet spans m consecutive microslots, so the parameter m provides a tunable trade-off between asynchronous access and fully synchronous slotted access. An analytical model including the finite demodulation-channel constraint of the central receiver is established under Poisson traffic, and the packet success probability and system throughput are derived. Monte Carlo simulations are used to validate the analytical results. Under the present assumptions, Multislot SSA occupies an intermediate operating point between Pure SSA and ideal Slotted SSA: Its throughput remains below the ideal slotted upper bound but above that of Pure SSA, whereas its distributed start phases provide a more implementation-friendly access structure. The results provide theoretical support for the design of massive random access in satellite short-burst communication systems.

CLEAR Interference Cancellation in a Wideband Dual‐Channel Receiver for Independent Satellite Multi‐Connectivity Links

Svilen Dimitrov — Mon, 01 Jun 2026 20:37:36 -0700

ABSTRACT

In this paper, the correlation learning estimation and adaptive reduction (CLEAR) of interference, an adaptive, blind and transparent interference compensation method applied in a wideband dual-channel receiver, is studied for a pair of independent satellite multi-connectivity links, using the same carrier frequency and signal bandwidth in use cases with or without polarization division multiplexing (PDM). The CLEAR method jointly processes the samples of the two channels after the corresponding analog-to-digital converters (ADCs), it has a low computational complexity and is suitable for very-high-rate implementations. This non-data-aided and non-decision-directed method is derived in a channel model with co-channel interference (CCI) and/or cross-polarization interference (XPI), including effects such as reduced cross-channel discrimination (XCD) and/or cross-polarization discrimination (XPD) of the receive antenna, depolarization due to atmospheric conditions, differential frequency offset (DFO) between the two channels, and power imbalance due to independent receive antenna gains. The resulting carrier-to-interference ratio C/I$$ C/I $$ and carrier-to-noise-and-interference ratio C/(N+I)$$ C/\left(N+I\right) $$ performance of the dual-channel receiver presents considerable energy efficiency improvements with this interference compensation method, and is particularly beneficial for higher-order modulation. As a result, the CLEAR method is a practical solution to increase the data rates of the satellite air interface in DVB-S2X/CCSDS and 5G NTN systems by the use of two independent satellite links.

Joint Optimization of Controller Placement and Switch Assignment in SDN‐Based LEO Satellite Networks

Zhiyun Jiang, Menglong Yang, Wei Li — Fri, 29 May 2026 21:45:38 -0700

ABSTRACT

Software-defined networking (SDN)–based low earth orbit (LEO) satellite networks utilize various characteristics of SDN to alleviate the problem of inefficient resource management under traditional network architectures. The most fundamental issue in SDN-based LEO satellite networks is how to place controllers and assign switches. The strategies adopted directly affect the network performance. However, most existing strategies cannot sensibly and dynamically adjust the controller location and controller–switch mapping according to the topology variation and traffic fluctuation of the LEO satellite network. In this paper, based on the dynamic placement dynamic assignment scheme, we first formulate the controller placement and switch assignment (CPSA) problem in the LEO satellite networks, which is an integer nonlinear programming problem. Then, a prior population–based genetic algorithm (PPGA) is proposed. Some individuals of the final generation of the algorithm for the current time slot are used as the prior population of the next time slot, thus stringing together the algorithms of adjacent time slots for successive optimization. Finally, we obtain the near-optimal solution for each time slot. Extensive experiments demonstrate that PPGA can adapt to the network topology changes and traffic surges and exhibits excellent robustness in the face of network failures, outperforming some existing CPSA strategies in the LEO satellite networks.

High‐Resolution Arbitrary Pattern Coverage Synthesis Using Adaptive and Iterative Fast Fourier Technique for Modern Satellite Applications

Ahmed Jameel Abdulqader — Thu, 28 May 2026 18:30:21 -0700

ABSTRACT

This paper contributes an advanced methodology for arbitrary pattern coverage footprint synthesis in sparse planar arrays using the adaptive and iterative fast Fourier technique (AIFFT), aiming to generate complex radiation patterns with high accuracy in terms of control of the main beam and sidebeam regions. A large-scale array of elements has been designed to generate a focused radiation pattern matching a regularly and irregularly shaped area. This area is defined by two mask colors derived from an outline of the map. The proposed model presents a sidebeam regions elimination of up to −30 dB, while maintaining very low ripple in the main beam coverage region, along with restricting the dynamic range ratio factor (DRRF) of the active elements' stimulus weights to a maximum value of 40 dB. The design process starts by constructing a radiation cover for two different regions in the spatial domain (u, v), where the main region represents the target geographic coverage area, while the side region is treated as the area to be strictly suppressed. Initial estimates for array element stimulations are obtained by performing the inverse Fourier algorithm on the softened copy version of the desired pattern coverage. Then, the AIFFT gradually optimizes the stimulations by moving between the spatial and frequency domains, imposing DRRF, ripple variation, signal-to-noise ratio (SNR), bit error rate (BER), and sideband region constraints at each iteration step. Computer simulation measurements explained the success of the algorithmic approach in generating a high-resolution pattern coverage that accurately matches the proposed geographic footprint. The study completed a side-interference level of approximately −30 dB, with essentially no ripple variation in the main beam region, and a very little number of non-zero elements, leading to reduced device complexity practically and improved energy efficiency. The results also demonstrated high SNR over the target coverage area of up to 30 dB for various assumed population densities, with a very low error rate of 10⁻⁵. This study demonstrates the potential of regular and irregular spatial masking regions and efficient spectral optimization for creating highly precise, tailored radiation patterns in next-satellite antenna arrays.

Impact of Station‐Keeping Strategies on VSAT Link Performance in GEO Satellites Under Adaptive Coding and Modulation

Oz Ibrahim, Yumusak Nejat — Wed, 27 May 2026 02:01:28 -0700

ABSTRACT

The demand for high-throughput satellite (HTS) services from Geostationary Earth Orbit (GEO) platforms continues to grow, driving the widespread adoption of advanced physical-layer techniques such as adaptive coding and modulation (ACM). ACM enhances link availability and spectral efficiency by dynamically adapting modulation order and forward error correction (FEC) in response to channel conditions, primarily targeting atmospheric impairments. However, an important and often underrepresented factor in GEO link performance is the impact of satellite orbital motion and station-keeping dynamics on antenna pointing accuracy. This paper investigates the effect of different station-keeping strategies on ACM-based VSAT link performance by comparing a chemically propelled satellite (Sat-C), and an electrically propelled satellite (Sat-E). Simulation results show that Sat-C exhibits average subsatellite point deviations of approximately 0.178°, compared to only 0.055° for Sat-E, leading to significantly higher pointing losses, particularly in Ka-band and for large antenna diameters. These variations translate into several decibels of additional link degradation, forcing frequent ACM downgrades from high-efficiency MODCODs (e.g., 16APSK/32APSK) to more robust modes such as QPSK. The results demonstrate that satellite station-keeping strategy is not merely an orbital control parameter, but a fundamental determinant of communication system efficiency that must be co-designed with ACM to realize the capacity of future GEO networks fully.

Directive Antenna Clutter Loss in Slant Paths

Fri, 22 May 2026 00:41:28 -0700

ABSTRACT

This paper investigates the development of a clutter loss model specifically for slant paths involving directive antennas. Conventionally, clutter loss is characterized by using isotropic antennas to facilitate standard link budget calculations via single antenna gain values. Clutter loss may represent a significant excess loss relative to free-space propagation. In scenarios such as coexistence interference between cellular and satellite systems, the former can employ highly directive, beam-steering architectures. Since the transmitter–receiver (Tx-Rx) link comprises multiple discrete propagation paths, each is subject to different antenna gains. This study proposes an extension to the five-ray model (5RM) for clutter loss to account for these differential gains. The methodology effectively characterizes paths from terrestrial transmitters to elevated platforms, including satellites, airborne systems, and Unmanned Aerial Vehicles (UAVs).

Dynamic Cell Division for Interference Management in Satellite Direct‐to‐Cell Systems

Satya Chan, Hee Wook Kim, Bon‐Jun Ku, Daesub Oh — Thu, 21 May 2026 00:36:15 -0700

ABSTRACT

Direct-to-cell (D2C) connectivity enables future non-terrestrial networks to provide service directly to standard terrestrial user equipment (UE) when terrestrial networks (TN) are unavailable. In this work, the satellite system is considered as a secondary network that supplements existing TN coverage while minimizing interference to the primary terrestrial infrastructure. To achieve this goal, we propose a dynamic cell-division framework in which satellite cells are adaptively formed to balance coverage and interference constraints. For UEs located near TN cells, a projected gradient descent algorithm is developed to place satellite cells as far as possible from the TN while maintaining user coverage. For UEs located far from the TN, a minimum covering cell (MCC) algorithm is employed to efficiently serve remote users while limiting the increase in the total number of cells. Simulation results demonstrate that the proposed method significantly reduces interference to the terrestrial network compared with conventional hexagonal cell layouts and the conventional MCC algorithm. In other words, the proposed method enables higher throughput without increasing the interference level compared to conventional approaches.

RL‐GA: An Optimization Strategy for Spatial Information Network Topology

Zhenxing Hu, Peng Yang, Jun Huang — Fri, 15 May 2026 08:32:08 -0700

ABSTRACT

Spatial information networks (SINs) are network systems characterized by their complex structure, high-speed operation, and extreme dynamics. Their intricate topology, involving a vast number of nodes and links, coupled with a harsh operating environment, makes them susceptible to both natural and man-made interference. This poses significant challenges to network stability. Therefore, the primary objective of topology optimization for SIN is to rapidly construct a network topology that is stable, highly connected, robust, and efficient. Previous optimization algorithms, including exact solutions based on dynamic programming and approximate solutions based on heuristics, struggle with limitations in escaping local optima and achieving rapid convergence. To address these drawbacks, this paper introduces a novel approach: a reinforcement learning–enhanced adaptive genetic algorithm (RL-GA). This framework integrates reinforcement learning to dynamically adjust the key parameters of the genetic algorithm, enhancing its ability to escape local optima and accelerate convergence. Experimental results, based on simulations of the Iridium and Qianfan satellite constellations, demonstrate that the proposed RL-GA algorithm outperforms existing methods in both solution quality (optimization results) and convergence speed. This advancement offers a more effective solution for SIN topology optimization, thereby enhancing the stability and efficiency of space-based communication networks.

Insights From the Alphasat Aldo Paraboni Experiment at Tito Scalo and Spino d'Adda: Characterizing Scintillation and Rain Attenuation at Ka‐ and Q‐Band Frequencies

Thu, 14 May 2026 06:31:11 -0700

ABSTRACT

We present experimental results on the relationship between rain attenuation and simultaneous scintillation during rain events, based on beacon signal measurements at 19.7 (Ka-band) and 39.4 GHz (Q-band) from the geosynchronous Alphasat satellite (25° E), received at two Italian ground stations, Spino d'Adda (42.1° slant path) and Tito Scalo (35.5° slant path). Time series data collected between 2015 and 2023 were processed at 16 Hz and filtered to isolate rain attenuation and scintillation components using fixed low-pass (0.05 Hz) and a band-pass (0.175–3 Hz) filters, respectively. The average rain attenuation A$$ A $$ (dB) and the average scintillation standard deviation σ$$ \sigma $$ (dB), computed in 1-min intervals, were found to follow a power-law relationship of the form σ=CA5/12$$ \sigma =C{A}^{5/12} $$ and σ=CA(5/12)/0.9$$ \sigma =C{A}^{\left(5/12\right)/0.9} $$, consistent with a thin turbulent layer. The models were fitted to the data over the attenuation range A$$ A $$ = 1.0–15.0 dB, where system noise has minimal influence, and their performance evaluated using mean squared error. The modified thin-layer model showed the best agreement overall, with lowest MSE values found when fitting the model to the Tito Scalo Ka-band and Spino d'Adda Ka- and Q-band data. Additionally, to demonstrate the thin-layer model's effectiveness, the models are examined briefly when frequency scaling the behavior of scintillations from 19.7 to 39.4 GHz. Among the models tested, the modified thin-layer model provided the best match to observed measurements when scaling. These results indicate that thin-layer turbulence models provide a physically consistent framework for characterizing rain-conditioned scintillation during rain events.

Low‐Complexity Hybrid Beamforming for LEO Satellites: Beam Update Rate Analysis and Advanced Adaptive Precoding

Mohammad Momani, Thomas Delamotte, Andreas Knopp — Thu, 14 May 2026 05:41:10 -0700

ABSTRACT

Low Earth Orbit (LEO) satellite constellations offer unprecedented opportunities for global broadband connectivity but pose significant beamforming challenges due to rapid platform motion and stringent onboard hardware constraints. Fully digital architectures, while optimal in theory, remain impractical for satellite payloads, motivating hybrid analog-digital designs that combine a reduced set of RF chains with analog phase shifter networks. In this work, we first quantify the required update rate for analog beam steering weights as a function of orbital altitude and array aperture size. We show that it is sufficient to update the analog beam steering vectors on the scale of seconds, even for larger arrays at lower altitudes. We then introduce a threshold-based algorithm that adaptively triggers analog beam steering updates, further reducing the frequency of steering events for a negligible sum-rate degradation. Finally, we propose an adaptive digital precoding (ADP) scheme that recomputes regularized zero-forcing (RZF)-based digital precoder only when interference leakage exceeds a tunable threshold, halving onboard matrix inversions for around a 6% average system sum-rate penalty. Monte Carlo simulations validate that these techniques jointly achieve near-optimal sum-rate performance while dramatically lowering both hardware and computational burdens, paving the way for practical, energy-efficient beamforming in next-generation LEO constellations.

Adaptive Beam Divergence for Different HAPS Altitudes in Satellite‐HAPS FSO Communication

Jitender Kumar, Soven K. Dana — Fri, 01 May 2026 19:25:26 -0700

ABSTRACT

Satellite communication fulfills the demand of global connectivity for next-generation networks. Free space optical (FSO) communication connects these high-bandwidth global links for seamless transmission. High altitude platform station (HAPS) improves the outage probability by relaying the signal when transmission to the long distances in one hop is not reliable. In this work, we consider adaptive beam divergence (ABD) technique for a low earth orbit (LEO) satellite, which transmits the FSO signal to the HAPS, where the divergence angle of the signal is selected based on the altitude of the HAPS. We considered the effects of threshold signal-to-noise ratio (SNR), receiver aperture diameter, jitter standard deviation, optical-to-electrical conversion efficiency and the horizontal distance between satellite and HAPS on the link outage probability. The results show that by using an appropriate beam divergence angle according to the height of the HAPS, the performance of the system improves. Additionally, it is observed that for a fixed outage probability, ABD achieves communication for longer transmission range with the HAPS located at an altitude, which is lower in comparison with the altitudes at lower and upper fixed divergence angles by 1.610 and 2.169 km, respectively.

Research on Large‐Scale Channel Model for Satellite–Terrestrial Communication Based on GBSM and NHMP

Dongxu Liu, Zhaoyang Su, Yuchen Cai, Yibo Gao, Yunxin Liang, Liu Liu — Tue, 28 Apr 2026 02:06:20 -0700

ABSTRACT

With the rapid development of LEO satellite communication systems, satellite–terrestrial integrated networks have become a crucial component of future 6G communication systems. However, the high-speed relative motion between satellites and terrestrial terminals forms a complex dual-dynamic communication scenario, which endows the channel with prominent time variability and nonstationarity, thus posing great challenges to the accurate modeling of large-scale fading. To address this problem, this paper proposes an integrated propagation probability calculation model that combines the GBSM with the NHMP. First, based on the Fresnel zone diffraction principle and stochastic geometry theory, this paper models urban buildings with Poisson and Rayleigh distributions and analytically derives the time-varying probability expressions for LOS propagation and reflected propagation. On this basis, aiming at the nonstationary switching of links among different propagation states, the NHMP model is constructed and the corresponding state transition matrix is derived, with the time-varying probability of integrated effective propagation solved by the forward Kolmogorov equation. The accuracy of the proposed model is verified via Monte Carlo simulation, which provides a universal large-scale channel modeling method for the satellite–terrestrial link budget in dual-dynamic scenarios.

Outage and Throughput Analysis of RSMA‐Enabled Satellite Downlinks Over Shadowed Rician Fading

Huu Q. Tran — Tue, 21 Apr 2026 22:50:58 -0700

ABSTRACT

Rate-splitting multiple access (RSMA) is a promising enabler for improving spectral efficiency, interference management, and user fairness in satellite downlink systems. Yet, most RSMA studies are either tailored to terrestrial settings or rely primarily on numerical optimization, offering limited analytical insight under satellite-realistic propagation such as shadowing. Motivated by geostationary Earth orbit (GEO) downlink operation, this paper provides a tractable performance analysis of an RSMA-enabled single-beam multiuser downlink over shadowed Rician fading. We consider a K$$ K $$-antenna GEO satellite serving Q$$ Q $$ single-antenna users with maximum-ratio transmission (MRT)–based precoding and perfect successive interference cancellation (SIC). Closed-form expressions are derived for the distribution of the effective channel gain, leading to exact and high-SNR outage probability characterizations. The resulting formulas explicitly reveal the roles of the antenna count (defined as the number of satellite transmit antennas K$$ K $$), shadowed Rician parameters, and RSMA power allocation. Furthermore, the analysis yields simple feasibility conditions that delineate practical operating regions for common/private power splitting. We obtain user and system throughput expressions and identify that the achieved diversity order equals K$$ K $$. Monte Carlo simulations validate the analysis and benchmark RSMA against nonorthogonal multiple access (NOMA) under various shadowing levels and power-allocation settings, highlighting reliability–rate trade-offs and providing actionable guidance for GEO satellite downlink design.

A New Space‐ and Time‐Correlated Tropospheric Attenuation Timeseries Synthesizer Driven by Low‐Resolution Meteorological Information for Earth–Space Communication Systems

Mon, 13 Apr 2026 21:40:21 -0700

ABSTRACT

Recommendation ITU-R P.1853-2 includes a stochastic approach to generate timeseries of total impairments that are correlated in time and space to support the design and operation of Satcom fade mitigation technique (FMT). Because it lacks any meteorological realism, it cannot reproduce realistic rainy/nonrainy periods or credible outage durations. We present a new modeling approach that combines meteorological data from the ERA5 reanalysis with stochastic components, preserving the required spatial–temporal correlations among several locations. The relative contribution of ERA5 and random terms is calibrated with high-resolution WRF-ARW simulations coupled to an electromagnetic module that converts 3D atmospheric information into microwave attenuation. With this hybrid model, ERA5 drives the slow dynamics while the stochastic part adds rapid fluctuations to the signal. Long-term ITU-R P. statistical models for rain, clouds, and water vapor transform normally distributed mixed processes into attenuation series; oxygen attenuation is computed directly from ERA5 variables, and scintillation is generated as in Rec. ITU-R P.1853-2. Model performance is assessed by comparing the complementary cumulative distribution function (CCDF) of many synthetic series with long-term ITU-R P. predictions, showing good agreement and revealing the climatic variance in the synthetic CCDF. Joint statistics are also evaluated against a new site-diversity prediction model that can handle more than two locations. Finally, fade and interfade durations are analyzed, demonstrating that the proposed synthesizer produces more realistic and longer outage and nonoutage periods than the original model from Rec. ITU-R P.1853-2.

Energy‐Efficient Optimization for RSMA‐Based Integrated Satellite–Terrestrial Networks Under Shadowed‐Rician Fading

Huu Q. Tran — Mon, 13 Apr 2026 05:18:22 -0700

ABSTRACT

This paper develops a unified analytical and optimization framework for rate-splitting multiple access (RSMA) in integrated satellite–terrestrial networks operating over shadowed-Rician fading channels. Closed-form integral expressions for the ergodic sum rate are derived using Meijer-G$$ G $$ functions, explicitly accounting for imperfect successive interference cancellation (SIC), multibeam satellite gains, and power splitting between common and private streams. Building on these expressions, a gradient-projection algorithm combined with Dinkelbach's method is proposed to optimize the power-split coefficients under quality-of-service and SIC constraints, jointly enhancing spectral and energy efficiency. Numerical and Monte Carlo results confirm the analytical accuracy and show that the optimized RSMA design achieves approximately 8%–20% ergodic sum-rate and 10%–18% energy-efficiency gains over non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA) baselines across both average and heavy shadowing conditions. The proposed framework provides implementation-oriented design insights into power-split adaptation and SIC robustness for future 6G non-terrestrial networks.

Demonstrating End to End Standards Based Beam Hopping With Commercial Equipment Derisking the Physical Layer Challenges

Mon, 13 Apr 2026 05:13:43 -0700

ABSTRACT

In the current high throughput satellite (HTS) systems, beams are continuously illuminated. To allocate bandwidth and avoid adjacent beam interference, spectrum and polarization are divided in disjunct and fixed portions, called FDM. In this paradigm, seamless flexibility to adjust beams to the demand can only be achieved by (1) an advanced and costly processing payload with flexible filter sizes and, in case of beamforming, circuits for all of the beams that are continuously illuminated, (2) make-before-break handovers requiring more expensive modems. Fortunately, there is an alternative providing seamless flexibility to adjust to demand, called beam hopping, where an on-board beam hopper illuminates a number of coverages, denoted cells (e.g., 8 cells), consecutively in time (hence TDM). The flexibility is achieved as the fraction of time by which each cell can be illuminated is configurable. As much less beams are simultaneously illuminated and no make before break (MBB) handover capability is required for the modems, this alternative is cheaper and less complex. The challenges to perform beam hopping are mainly situated at the physical layer, which have been addressed already partly by standardization (DVB-S2X, annex E formats 5, 6 and 7), by proprietary payload implementations with beam hopping and several funded ESA projects. This paper reports work from the ESA Free Hopper projects, which intends to fully validate and derisk an end to end HTS system with standards based beam hopping with commercial equipment from iDirect, Easii-ic (chip based receiver), Airbus (ABFN), and Honeywell (ferrite switches). The paper focuses on the gateway modulator architecture and the “ground only” synchronization mechanism, which is currently implemented and tested. The synchronization time-aligns the waveform with a transparent beam hopping satellite and then remains time aligned (taking into account satellite movement and clock drifts), without requiring a terminal to be collocated with the gateway transmitter.

A Scalable, High‐Performance, Standards‐Based Approach to Linear Precoding for the Multi Spot Beam Satellite User Downlink

Mon, 13 Apr 2026 05:13:43 -0700

ABSTRACT

Linear precoding is a means to increase the throughput of the multi spot beam satellite user (forward) downlink by facilitating aggressive frequency reuse compared to a 4-color reuse scheme. We propose a new way to apply the DVB-S2X standard in the context of precoding. The approach sidesteps the need to align physical layer frames of simultaneous users on jointly precoded carriers. Hence, physical layer frames can be scheduled more freely by per carrier independent adaptive coding and modulation processes. By introducing the concepts of superframe virtual carrier (SFVC) and dedicated estimation SFVC (ESFVC), a carrier can still be shared by multiple users. In the legacy use of DVB-S2X for precoding there are syntax elements (non-precoded pilots) that have dual use: for channel matrix estimation and as demodulation reference for precoded data symbols. We will demonstrate an adverse effect of this legacy approach and provide a remedy. We further sidestep the need for pre-calibration of differential delays between jointly precoded carriers of large bandwidth in the satellite and gateway RF paths. This is achieved by providing, while staying entirely within the syntax rules of the DVB-S2X standard, a large non-precoded field, eventually aligned and quasi-orthogonal among carriers, however already suitable for estimating the channel matrix and differential time delays even in the presence of initial delay differences exceeding one symbol period. The latter is not the case for methods described in the DVB-S2X standard's guideline. Finally, we describe how to organize aggressive frequency reuse over large areas served by overlapping spot beams in a scalable way, sticking to small precoding domains and decentralized processing. This contrasts with the concept of a centralized gateway presented elsewhere and sidesteps the need for fine time/frequency alignment of jointly precoded carrier feeds from different RF gateways.

Improving the Estimation of Attenuation in Q/V Band Systems With a Kalman‐Based Scintillation Filter

Justin Cano, Julien Queyrel, Laurent Castanet, Michel Bousquet — Mon, 13 Apr 2026 05:13:43 -0700

Abstract

This paper presents the design and implementation of a scintillation filter by Kalman-colored algorithm (SciFi), which is used to remove tropospheric scintillation in Q/V band total attenuation time series. In contrast to the classical methods using low-pass filters, the SciFi algorithm allows to estimate both the attenuation, its slope and a confidence interval. Moreover, the linear observer structure of the Kalman filter allows real-time operation. Therefore, the states and uncertainties estimated by SciFi can be used as input for fade mitigation techniques (FMT) such as adaptive coding and modulation (ACM) or site diversity (SD). In this article, a method to tune the estimator based on ITU-R recommendations is proposed. Finally, some time-series and statistical results of filtering on Alphasat experimental data are discussed.

Advanced Fade Mitigation Techniques for Q/V Band SATCOM Systems

Mon, 13 Apr 2026 05:13:43 -0700

ABSTRACT

Adaptive fade mitigation techniques, such as smart gateway diversity (SGD), are essential in addressing atmospheric fading affecting the operation of high throughput and very high throughput satellite systems at Ka-band and beyond. Specifically, the Q/V-band, offering up to 5 GHz of available spectrum, is very attractive for future high data rate services, but it is especially susceptible to atmospheric attenuation, with rain posing a significant challenge. This paper presents a simulation model for the design and performance assessment of a Q/V-band SATCOM (satellite communication) system. The model consists of two primary modules: (1) a physical model of the propagation channel, which integrates numerical weather predictions (NWPs) with a radiopropagation simulator and a temporal downscaling module; (2) a system simulator that operates SGD alongside traditional fade mitigation techniques, that is, uplink power control (ULPC) for the uplink and adaptive coding and modulation (ACM) for the downlink. The latency of SGD emerges as a critical parameter that constrains system performance (e.g., carrier to noise plus interference ratio and data rate) when compared to an ideal system capable of real-time traffic switching. This study explores the impact of varying SGD latency times on the performance of a Q/V-band SATCOM system, providing insights into system behavior under realistic conditions.

Dynamic Predictive Routing for Satellite Megaconstellations

Mike Greenwood, Rob Hunter, Afonso Nunes — Mon, 13 Apr 2026 05:13:43 -0700

ABSTRACT

Emerging low-Earth orbit (LEO) satellite mega-constellations introduce new challenges in traffic engineering due to their scale and highly dynamic topologies. This paper presents dynamic predictive routing (DPR), a machine learning approach that leverages graph neural networks (GNNs) and gradient-free optimization to enhance routing performance in constellations with intersatellite links (ISLs). Unlike traditional heuristics such as Dijkstra or Bellman–Ford, which react to current topology states, DPR anticipates short-term network evolution and proactively redistributes traffic to reduce congestion. Through simulation and emulation, we show that DPR outperforms baseline routing, achieving up to ~9% congestion reduction in highly loaded networks, with scalability to larger constellations. A GPU-optimized path algorithm further accelerates computation, enabling feasibility in resource-constrained environments. The vision at the heart of all mega-constellations is a very wide area network (VWAN) with latency competitive to terrestrial fiber. While routing challenges exist in any mesh network, they are particularly critical in LEO systems, where orbital dynamics, scarce spectrum, and limited gateways intensify performance pressure. As capacity becomes a premium resource, dynamic optimization is essential to extract maximum value from the orbital real estate. An intelligent routing fabric can unlock greater throughput without proportional hardware expansion, support differentiated services, and integrate operational constraints directly into planning and decision-making. In this paper, we describe the training methodology, including live interaction with simulated and emulated networks, and present results showing consistent congestion reduction, modest latency trade-offs, and scalability. Importantly, the alignment of performance gains across simulation and emulation provides a strong basis for operational deployment. Further optimization remains feasible when tailoring DPR to specific network constraints.

Deeper dive into interoperability and its implications for LunaNet communications and navigation services

Mon, 13 Apr 2026 05:13:43 -0700

Interoperability provides cislunar users the ability to operate in a collaborative environment similar to the terrestrial Internet. This paper reports on the development of the international LunaNet architecture, examining architectural and operational implications and exploring interoperability strategies and tactics to deploy and evolve the services proposed for cislunar missions.

Summary

The Artemis program being developed by the United States' (US) National Aeronautics and Space Administration (NASA) is advancing capabilities to return humans to the Moon and establish an initial base camp and associated infrastructure with extensive contributions from international and commercial partners. In planning for cislunar exploration and science missions, space agencies are collaborating to enable communications, networking, and Positioning, Navigation, and Timing (PNT) systems—called LunaNet—to exchange information and provide services to cislunar spacecraft and space systems, thus helping each other to achieve their shared goals. To achieve commonality and lower cost for mutual benefit, the strategy of interoperability is being adopted to help fit all the pieces together and function smoothly. Facilitating interoperability should benefit lunar missions by providing the ability to operate in a collaborative environment similar to the terrestrial Internet. Interoperability allows them to share information, navigate safely despite increasing radio frequency congestion, and follow common processes and procedures for effective joint operations. Unlike prior government-dominated efforts, this ecosystem is expected to include and benefit for-profit (commercial) businesses, non-profit organizations, and academic institutions as active stakeholders. Ultimately, the goal is to enable a cislunar ecosystem of service providers and users to contribute to and/or utilize infrastructure and capabilities to achieve mission objectives that span the full range of human endeavors while supporting a variety of business models. This approach enables a Systems of Systems (SoS), such as a Network of Networks, to be sustainable in the context of the LunaNet ecosystem as systems evolve over time in technologies, standards, components, and user applications. This paper reports on the results of an effort to help frame the development of the international LunaNet architecture by providing a canonical definition of interoperability broad enough to meet these needs, examining architectural and operational implications of the definition, and exploring interoperability strategies and tactics to deploy and evolve the services proposed for cislunar exploration and science missions.

DVB Standard Support of NGSO Systems

Mon, 13 Apr 2026 05:13:43 -0700

ABSTRACT

The DVB project has been active in maintaining and adapting its specifications to the requirements of modern satellite communications systems. The physical layer specifications, which include DVB-S2X for the forward link and DVB-RCS2 for the return link, have been recently updated to support beam hopping over the forward link and signaling within a VSAT system, including some support of nongeostationary orbit (NGSO) satellites. Last year, the DVB Commercial Module issued a new set of requirements for further support of NGSO by the DVB-RCS2 standard. The requirements call for support and analysis of operation within an NGSO system and extending the capabilities of the return link to support higher capacity and enable more symmetric traffic. The DVB Technical Module (satellite working group, TM-S) has produced an enhancement of the specifications and performed a set of analyses to answer the commercial requirements. In the paper, the new features described above will be introduced, as well as the analyses and discussions.

Special Issue: Best Papers From the 29th and 30th Ka and Broadband Space Communications and Navigation Conferences

Barry Evans — Mon, 13 Apr 2026 05:13:43 -0700

International Journal of Satellite Communications and Networking, Volume 44, Issue 3, Page 213-215, May/June 2026.

Issue Information

Mon, 13 Apr 2026 05:13:43 -0700

International Journal of Satellite Communications and Networking, Volume 44, Issue 3, May/June 2026.

5G‐NR GNSS Independent Time and Frequency Synchronization in NTN Scenarios

Philippe Delbeke, Dieter Duyck — Mon, 13 Apr 2026 05:13:43 -0700

ABSTRACT

In recent years, we observed a growing interest to re-use the terrestrial 5G-NR waveform over satellite or non-terrestrial networks (NTNs). The 5G-NR radio waveform is based on multi-carrier orthogonal frequency division multiplex (OFDM) modulation while existing satellite waveforms like DVB-S2X and DVB-RCS are based on square root raised cosine (SRRC) pulse-shaped single carrier transmissions. Next to some clear advantages of OFDM for multi-channel transmissions, there are some drawbacks. A critical disadvantage is the higher sensitive of the OFDM waveform to time and frequency misalignment of the terminal. Terminal misalignment in time or frequency will result in non-orthogonality of the different subcarriers and cause intersymbol interference (ISI) and intercarrier interference (ICI). 5G-NR thus requires tighter time and frequency synchronization than existing satellite waveforms. The 5G-NR standardization body (3GPP) has put forward the use of global navigation satellite systems (GNSS) and satellite orbit information to pre-compensate the mobility effects. The aim of the present solution is to avoid the GNSS information and satellite orbit data dependency for reliable communication. This paper will first review the critical synchronization accuracy needs and the Doppler requirements for 5G-NR NTNs. Next, we explore different time and frequency tracking options highlighting their shortcomings, and finally, we propose a novel solution based on higher order closed loop tracking.

A decade of EHF scientific research: Unveiling insights from Alphasat Q/V‐band satellite communication experiments

Mon, 13 Apr 2026 05:13:43 -0700

This paper presents a comprehensive analysis of the scientific outcomes obtained from a decade-long series of Q/V-band satellite communication experiments conducted via the Alphasat “Aldo Paraboni” payload. Core research areas encompassed channel estimation, prediction, and modeling, along with the development of propagation impairments mitigation techniques and the exploration of opportunistic utilization of EHF satellite links.

Summary

In 2008, the Italian Space Agency (ASI) consolidated its position on research and experiments regarding extremely high frequency (EHF) satellite communication through the proposal to the European Space Agency (ESA) of hosting a Q/V-band experimental payload on board the Alphasat geostationary satellite. The latter large platform, launched in 2013, thus hosted the so-called TDP#5 (Technology Demonstration Payload), aimed at performing the first Q/V-band telecommunication and propagation experimental campaigns. Thanks to the precious contribution given to the definition of the overall mission and the scientific objectives, the payload was then renamed in memory of Professor Aldo Paraboni, pioneer of scientific research on EHF satellite propagation.

Since 2014, a large number of satellite communication scientific experiments have been conducted by the University of Rome Tor Vergata, principal investigator for the ASI telecommunication campaign. Due to the excellent scientific results and the high reliability of the system, the experimental campaign is still ongoing. The main objective of the proposed telecommunication experiments is to demonstrate the feasibility of broadband satellite communications in Q/V band, optimizing and assessing, over-the-air, the performance of the indispensable adaptive transmission techniques. Moreover, the application of innovative paradigms related to software-defined networking (SDN) and network functions virtualization (NFV) has been investigated in the framework of satellite systems exploiting beyond Ka-band frequencies.

The goal that drives this experimental activity is to provide to the academic community, manufacturers, and service providers useful tools to cope with Q/V-band links for future satellite communication systems. The use of EHF links contributes to the reduction of RF front end and thus minimization of orbital junk; moreover, high throughput links in conjunction with software-driven architectures enable a high level of system reconfigurability that is one of the pillars for a sustainable use of space.

The paper presents the main results of the last 10 years of Q/V-band experiments, as well as the plans and perspectives for future scientific and operational activities in a sustainable space framework.

Location‐Assisted Graph‐Based User Scheduling in Multi‐User MIMO LEO NTN Systems

Mon, 13 Apr 2026 05:13:43 -0700

ABSTRACT

This paper addresses user clustering and scheduling for multi-user MIMO low Earth orbit nonterrestrial network systems in full frequency reuse. Since the number of on-ground user terminals is usually much higher than the number of on-board LEO satellite antennas, user scheduling becomes a fundamental task. We accomplish user scheduling by grouping users into clusters. Users within the same cluster are served by the satellite at the same time by means of space division multiplexing via location-based feed space digital beamforming. Each cluster is then assigned to a distinct time slot and served by means of time division multiplexing. Given the full frequency reuse nature of the system, we design user scheduling algorithms with the goal of maximizing the average per-user throughput while minimizing the co-channel interference and preserving fairness among users. To this aim, we propose in this paper (a) a distance-based iterative graph-based scheduler based on the maximum clique approach and (b) a distance-based implementation of the multiple antenna downlink orthogonal user clustering algorithm. For both these schedulers, the great circle distance between the users is employed as a dissimilarity metric to compute the user adjacency matrix, avoiding the need for the transmission of downlink pilots for channel state information estimation. To further validate our analysis, the proposed approaches are compared with (a) channel state information-based graph and maximum clique approach and (b) original multiple antenna downlink orthogonal user clustering algorithm. Extensive simulations assess the achievable per-user throughput and signal-to-noise plus interference ratio achieved by the proposed schedulers, highlighting the impact that the distance-based metric has on the system performance. This study provides valuable insights into the effective use of user scheduling algorithms.

Monte Carlo Throughput Estimation in Dynamic LEO Satellite Networks

Wed, 08 Apr 2026 18:39:26 -0700

ABSTRACT

This study introduces a comprehensive framework for analyzing capacity dynamics and throughput performance in low Earth orbit satellite networks (LSNs) with unreliable intersatellite links (ISLs). It addresses two critical limitations of prior models: (1) the lack of capacity and throughput evaluation under dynamic network conditions, an inherent and unavoidable characteristic of LSNs, and (2) the inability of flow-network models (e.g., maximum flow) to estimate throughput under specific, practical routing schemes, as they inherently assume traffic is routed according to an optimal flow distribution. To address these challenges, we propose the capacity model under a dynamic LSN (Cap-DLSN), which characterizes the time-varying link capacity under stochastic ISL failures, along with a Monte Carlo throughput estimation (MCTE) framework that evaluates network throughput under dynamic traffic and diverse routing policies. Simulations on operational constellations show that MCTE provides realistic and computationally efficient performance benchmarks, offering practical guidance for routing optimization or network design in next-generation LSNs.

Secure Satellite Communication in the Post‐Quantum Era: A Lattice‐Based Cryptographic Approach

Tutan Ghosh, Ira Nath — Wed, 18 Mar 2026 04:57:14 -0700

ABSTRACT

Quantum computing poses a looming threat to the cryptographic primitives that secure today's satellite communications. In response, post-quantum cryptography (PQC) has emerged to protect data against future quantum-enabled adversaries. This paper provides a comprehensive analysis of lattice-based PQC methods for secure satellite communication in the post-quantum era. We examine the performance and security of leading lattice-based schemes—including encryption/key-establishment algorithms like CRYSTALS-Kyber and NTRU, and digital signature schemes like CRYSTALS-Dilithium and FALCON—in the context of satellite systems. Real-world benchmark data from peer-reviewed sources are used to evaluate computational efficiency, bandwidth overhead, memory footprint, and energy consumption of these schemes on resource-constrained satellite hardware. We compare lattice-based approaches with classical RSA/ECC and alternative post-quantum techniques (hash-based signatures, code-based encryption), highlighting the favorable trade-offs that have led to lattice-based algorithms becoming primary candidates for standardization. Security analysis is presented to explain the hardness assumptions (e.g., Learning With Errors and NTRU problems) that underpin lattice cryptography, and to assess known cryptanalytic results, resistance to quantum attacks, and remaining security margins. We also discuss practical considerations for deploying lattice-based cryptography on satellites, including integration into existing communication protocols, potential need for hardware acceleration, and strategies for cryptographic agility in long-lived space assets. The results show that lattice-based PQC can be feasibly implemented in satellites with acceptable performance impact, providing strong security against quantum threats and a viable path to future-proof the confidentiality and authenticity of satellite communications.

Lookahead‐Based Lookaside Selection: Mitigating Inline Frequency Interference Between Satellite Constellations

Huiliang Liu, Fei Peng, Zhe Zhang, Yao Chu — Fri, 13 Mar 2026 00:25:50 -0700

ABSTRACT

The densification of non-geostationary orbit (NGSO) constellations has made co-frequency interference (CFI) a critical bottleneck for system capacity, particularly inline interference events where angular separation between heterogeneous satellite systems approaches zero. Existing mitigation strategies, such as spatial isolation or reactive handovers, often suffer from myopic decision-making, resulting in either persistent interference or excessive signaling overhead. This paper proposes a proactive lookahead-based lookaside selection algorithm to mitigate inline CFI in dynamic NGSO environments. By modeling satellite selection as a receding horizon optimization problem, the proposed algorithm integrates multi-step trajectory prediction, a temporal discount factor, and explicit switching penalties to optimize the long-term radio frequency environment. Simulation results using Walker-type constellations over a 30-day period demonstrate that the proposed method effectively eliminates severe interference events. At high latitudes (60° N), the probability of angular separation falling below 5° is reduced to 0%, compared to 1.1% for conventional highest-elevation strategies. Similar robustness is observed at lower latitudes and in challenging co-inclined “chasing” scenarios. Crucially, this performance is achieved with a balanced operational cost: Daily handovers increase by only 64% relative to stability-first baselines, while remaining 70% lower than elevation-maximization strategies. Parametric analysis further reveals that the optimal lookahead horizon correlates strongly with the average satellite pass duration, establishing a design guideline for proactive interference management in future 5G/6G-integrated non-terrestrial networks.

Outage–Throughput Performance of RSMA‐Enabled GEO Multibeam Satellite–Terrestrial Downlink Systems

Huu Q. Tran — Tue, 10 Mar 2026 10:57:47 -0700

ABSTRACT

This paper presents an analytical framework for evaluating the outage–throughput performance of rate-splitting multiple access (RSMA) in GEO multibeam satellite–terrestrial downlink systems operating over shadowed–Rician fading channels. Closed-form expressions are derived for the outage probability and system throughput under the baseline assumption of perfect successive interference cancellation (SIC), accompanied by asymptotic analysis revealing the diversity gain achieved with multiple satellite antennas. The proposed model is developed for a general Q$$ Q $$-user GEO multibeam downlink and specializes to the two-user configuration for numerical illustration, while a separate discussion is provided on how the outage, throughput, and computational complexity scale with Q$$ Q $$. In addition, an explicit design for the common message precoding vector is specified as a weighted combination of user channels, enabling a quantitative assessment of its impact on link reliability and spectral efficiency. To better match practical satellite receivers, an imperfect SIC model is introduced, where a residual interference factor captures decoding errors and leakage, and its effect on outage probability, throughput, and robustness is analyzed. A simple yet effective power allocation strategy is also discussed: We formulate a throughput-maximization problem with outage constraints and then motivate the adopted power-splitting coefficients through offline search and sensitivity analysis. Monte Carlo simulations validate the analytical results and demonstrate that RSMA achieves significant gains over NOMA, especially under moderate and heavy shadowing conditions.

Tracing Three Decades of Low Earth Orbit Satellite Communication Development: A Bibliometric and Main Path Analysis of Network Architectures, Protocol Evolution, and Emerging Intelligent Services

Wei‐Hao Su, Ya‐Chen Chuang, Long‐Sheng Chen — Fri, 06 Mar 2026 00:00:00 -0800

ABSTRACT

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.

Preprocessing Procedure for Propagation Measurements on MEO Satellite Links

Marlene Brás, Susana Mota, Armando Rocha — Fri, 06 Mar 2026 00:00:00 -0800

ABSTRACT

This paper presents a software tool designed for preprocessing data from an experimental campaign aimed at characterizing the tropospheric propagation channel using Medium Earth Orbit (MEO) satellites. The collected data provide critical insights into the channel in scenarios involving continuous variations in azimuth and elevation, along with frequent satellite handovers. This work presents the challenges associated with extracting attenuation time series from measured signal levels and outlines the solutions developed to accelerate this process in a multisatellite observation context. The software efficiently integrates beacon amplitude time series, antenna pointing data, receiver parameters, and meteorological records into a unified framework, enabling users to assess measurement conditions and apply both automated and manual classification techniques to the extracted time series. Additionally, the data structures, algorithms, and manipulation techniques designed to leverage multiple data channels are detailed, ensuring precise qualification of beacon propagation data. A step-by-step preprocessing procedure using 1 day of real data is presented. The retrieved attenuation time series is compared with Ka-band Geostationary satellite measurements, highlighting interchannel differences. In addition, selected cumulative statistics are reported.

Integrated LEO Constellation and In‐Cabin Distribution System for Continuous Aircraft 5G Connectivity

Mon, 23 Feb 2026 00:00:00 -0800

ABSTRACT

The integration of low Earth orbit (LEO) satellite constellations with commercial aircraft communication systems presents critical challenges in maintaining continuous connectivity during dynamic flight conditions. Current geostationary satellite systems suffer from high round-trip latency (>$$ > $$ 500 ms) and inadequate coverage at high latitudes, limiting their utility for modern aeronautical applications. This study presents an integrated aerospace systems architecture combining LEO satellite constellation management with in-cabin signal distribution networks to achieve uninterrupted 5G connectivity for aircraft. A simulation framework incorporating orbital mechanics, adaptive handover algorithms, and 3GPP-compliant ray tracing techniques evaluates system performance across transcontinental routes. Results demonstrate 97.78% connectivity reliability using sequential satellite insertion with 8–10 LEO satellites along a 2500-km flight corridor, achieving handover success rates of 97.5% with execution times of 150–250 ms. In-cabin signal analysis using distributed 4×$$ \times $$8 MIMO antenna arrays achieves 58.55-dB average path loss with 3.2-dB standard deviation across passenger areas. Performance validation under extreme operational scenarios (transpolar routes, emergency descent, and takeoff/landing phases) confirms >93%$$ >93\% $$ connectivity maintenance across all flight phases. These findings provide aerospace systems designers with quantitative performance metrics and architectural guidelines for next-generation satellite-based aircraft communication systems, addressing critical gaps in handover optimization, signal distribution, and operational robustness for commercial aviation applications.

A Delay Jitter Control Method for LEO Satellite Communications Based on Disturbance Modeling and Temporal Convolutional Networks

Yibo Gao, Xianglong Duan, Zhaoyang Su, Yuchen Cai, Liu Liu — Sun, 22 Feb 2026 19:35:45 -0800

ABSTRACT

As an essential complement to terrestrial networks, low Earth orbit (LEO) satellite networks constitute a critical component of the future integrated space-air-ground network architecture. Owing to the high mobility of LEO satellites and the long propagation distance of satellite-to-ground links, the system faces significant delay jitter issues, which adversely affect communication, real-time performance, and stability. This study proposes a temporal dynamic convolutional network model that adapts to the elevation angle by considering the orbital dynamics of LEO satellites and environmental variations in the ionosphere and troposphere along the satellite-ground propagation path. The proposed model enables effective modeling and dynamic compensation of propagation delay jitter under different orbital altitudes and elevation angle conditions. The simulation results demonstrate that the proposed method achieves high accuracy in delay prediction and jitter suppression, providing a robust design basis and technical support for delay optimization in LEO satellite communication systems.

Path‐Based Deep Reinforcement Learning for On‐Board Routing in Satellite Constellation Networks

Fri, 20 Feb 2026 00:51:59 -0800

ABSTRACT

Efficient usage of available network resources is a crucial factor for broadband services in interconnected satellite constellations. To meet required quality of service standards under heavy network loads, it is essential to optimize traffic distribution among the intersatellite links. To address this challenge, we propose an adaptive traffic engineering framework based on deep reinforcement learning. Our approach employs a path-based decision-making strategy, using a centralized agent to distribute incoming flow requests on a set of candidate paths. This method approximates optimal solutions to the multicommodity flow problem with relatively low computational complexity, making it suitable for in-space network control despite on-board processing limitations. The performance of the proposed scheme is evaluated against state-of-the-art rule-based benchmarks in various scenarios. We quantify the impact on performance of different candidate path sets and traffic patterns. Overall, the proposed solution presents a viable approach for optimizing flow distribution in satellite constellation networks, suitable for the integration into the controller logic of software-defined networks.

A QoS Supported Carrier Planning and Timeslot Allocation Algorithm for the Return Link of GEO Satellite

Cao Huang, Wei Sun, Yanan Zhou, Guangxiu Pan, Feiteng Luo — Tue, 17 Feb 2026 15:09:20 -0800

ABSTRACT

To tackle the significant challenge of achieving the frequency domain and time domain resource allocation on the Geostationary Earth Orbit (GEO) satellite return link, we develop a two-tier “Carrier Planning-Timeslot Allocation” cooperative resource-management framework to optimize system efficiency and different quality of service (QoS) for diverse user demands simultaneously. The Dynamic Planning Carrier Configuration (DPCC) algorithm continuously reconfigures the frequency carrier set through a multi-layer aggregation and proportional allocation procedure, in which the share granted to each carrier tier is steered by the weighted traffic demand of every priority class and the prevailing channel fading severity. The Timeslot Allocation under Fixed Carriers Set (TAFCS) algorithm initially utilizes a modulation and coding (MODCOD) update mechanism to exploit favorable channel conditions. Then it conducts scheduling in three successive phases “priority-driven allocation, idle-slot aggregation and reuse, and residual-request slicing”. Extensive Satellite Network Simulator 3 simulations show that TAFCS alone outperforms the first-fit algorithm and the Reserve Channel with Priority (RCP)-fit algorithm, boosting timeslot utilization and return channel satellite terminal (RCST) response rates by roughly 8%–11% while meeting QoS targets across high-/medium-/low-priority traffic. When DPCC is introduced, the simulation under seven scenarios with diverse traffic and channel dynamics confirms that the DPCC-TAFCS framework markedly surpasses single-layer TAFCS on both system efficiency and QoS support, while demonstrating robust effectiveness under harsh link conditions.

Three‐Year Propagation Experiment at Ku‐, Ka‐, and Q‐Band in French West Indies

Jean‐Pascal Monvoisin, Laurent Castanet, Laurent Féral, Xavier Boulanger — Tue, 10 Feb 2026 23:55:58 -0800

ABSTRACT

From January 2021 to December 2023, the Office National d'Etudes et de Recherches Aérospatiales (ONERA) and the Centre National d'Etudes Spatiales (CNES) conducted a three-year Earth-space propagation measurement campaign in Guadeloupe. The experiment used beacon receivers deployed in Pointe-à-Pitre airport to record signals at 11.2, 19.7, and 39.8 GHz from E65WA satellite. A rain gauge was also installed on site to collect concurrent rainfall rate measurements alongside beacon data. The availability of the data is close to 100% for the first 2 years of the experiment and higher than 95% over the full duration of the experiment at all three frequencies. This paper presents an analysis of the collected data to enhance the understanding of propagation effects in tropical environments. First, the climatic characteristics of Guadeloupe are shown to contextualize the study. Second, the propagation experiment setup and the data processing methodology are described. Third, experimental statistics of rain attenuation and rainfall rate are provided. The results are compared with the prediction methods of Recommendation ITU-R P.837-8 (rainfall rate), Recommendation ITU-R P.618-14 (rain attenuation and frequency scaling) and Recommendation ITU-R P.16231 (fade slope and fade duration) to evaluate their accuracy in tropical areas.

Anti‐Jamming Satellite Communication Based on Blind Source Separation: Problems and Challenges

Jiong Li, Lijuan Gao — Thu, 29 Jan 2026 17:24:37 -0800

ABSTRACT

Spread spectrum communication technology is one of the most critical core technologies in anti-jamming satellite communication systems. However, it has certain technical limitations in anti-jamming applications. For instance, frequency-hopping spread spectrum technology exhibits weak resistance against spot jamming, while direct-sequence spread spectrum technology is less effective in mitigating wideband interference. With the continuous development of satellite countermeasure technologies, these technical limitations will significantly constrain the performance of satellite communication systems and compromise the reliable transmission of space-based information. Aiming at the technical limitations of spread spectrum anti-jamming satellite communication, this paper proposes a solution based on blind source separation technology to enhance the anti-jamming capability of spread spectrum communication. This paper establishes a blind source separation-based anti-jamming communication prototype system, verifying the feasibility of applying blind source separation to communication anti-jamming. It conducts an in-depth analysis of the characteristics and existing issues in spread spectrum anti-jamming satellite communication systems, identifies the problems and challenges of applying blind source separation to such systems, and proposes potential solutions.

Comprehensive Review on Performance Analysis for Satellite Communication MIMO Over Terrestrial Communication MIMO

Shradha Kumari, Ashraf Hossain — Thu, 22 Jan 2026 00:46:12 -0800

ABSTRACT

This paper presents a thorough review on technical and physical comparison between the implementation of satellite MIMO (multiple-input multiple-output) and terrestrial MIMO. The technological improvements in satellite MIMO over terrestrial MIMO which are absent in related previous works are additional with this survey paper. Most of the applications for heterogeneous user cases are feasible due to diversity performances and shortening the digital divide with facility of higher data rate capacity to remotely located and underserved areas. Over and above that suitable antenna design, perspectives to achieve satisfactory performance metrics like number of ports, slot effects, isolation factor, metamaterial are considered, while multiple antenna elements are also carried out for executing MIMO performance over satellite. Adaptive beamforming and multiplexing are the potential characteristics of MIMO technology which makes the device more feasible for high potential applications of satellite communication (SatCom) in various applications that demand higher capacity and enhanced coverage for ultrareliable wireless communication system. Various constellation satellites such as LEO (low earth orbit), MEO (medium earth orbit), and GEO (geostationary earth orbit) are categorized according to their altitude, elevation angle, and their applications. Exploitation of diversity performance to accomplish the critical services along with global coverage is an excellent service provided by satellite MIMO communication system. Furthermore, challenges associated with installation of MIMO with SatCom are analyzed, and benefits along with difficulties are introduced.

Adjacent Satellites Collaborative Beam Hopping–Based Interference Avoidance Technique for LEO Satellite System

Chao Zhang, Xiangyu Gan, Guang Liang, Xinglong Jiang, Huawang Li — Mon, 19 Jan 2026 22:02:16 -0800

ABSTRACT

Low earth orbit (LEO) satellite communication system can achieve global coverage and has attracted widespread attention. However, the common demand for broadband satellite spectrum resources inevitably leads to cofrequency interference between LEO and geostationary orbit (GSO) satellite communication systems. To meet interference avoidance requirements while ensuring LEO system performance, this paper proposes an adjacent satellites collaborative beam hopping–based interference avoidance technique for GSO–LEO coexistence systems. First, the adaptive demand satisfaction ratio user grouping method is developed to accommodate the energy efficiency weight factor in resource efficiency (RE). Meanwhile, a residual demand priority adjacent satellites collaborative greedy user scheduling scheme is employed to enhance LEO system capacity while avoiding severe interference to GSO systems. Subsequently, a quadratic transformation–based convex optimization power allocation is proposed to further improve LEO system RE and reduce cofrequency interference. Finally, the above steps are alternately iterated timeslot by timeslot to obtain the local optimal user scheduling strategy and power allocation scheme over the beam-hopping period. Simulation results validate that the proposed technique effectively mitigates interference while achieving optimal performance in multiple indicators including RE.

Cognitive Orbital Mesh Beamforming (COMB) for LEO Satellite Networks: A Performance Simulation Framework

W. Belgacem, N. Belgacem — Mon, 05 Jan 2026 23:35:16 -0800

ABSTRACT

The rapid evolution of 6G non-terrestrial networks (NTNs) demands innovative solutions to address the challenges of high-mobility low Earth orbit (LEO) satellite communications, including dynamic channel conditions, Doppler shifts, and adversarial threats. This paper proposes a Quantum- Integrated OTFS-RIS Framework with AI-Driven Security, tailored for 6G NTNs. The framework combines Orthogonal Time Frequency Space (OTFS) modulation with reconfigurable intelligent surfaces (RIS) to enhance throughput and robustness, leveraging quantum computing for real-time delay-Doppler channel prediction and optimization. An AI-driven decision engine, integrating advanced recurrent neural network-transformer models and machine learning-based attack detectors, dynamically adjusts RIS phase shifts and relay trajectories, achieving up to 30% throughput gains and significant bit error rate (BER) reductions compared with conventional schemes. Security is fortified through quantum key distribution (QKD) and AI-enhanced physical layer security (PLS), mitigating jamming and eavesdropping while maximizing covert rates. Simulation results, validated in a multi-user massive MIMO LEO environment, demonstrate superior spectral efficiency, energy optimization, and resilience against adversarial interference, positioning this framework as a cornerstone for secure, scalable 6G NTN connectivity.

Beyond 5G and Non‐terrestrial Network (NTN) Integrated Architecture: Access Challenges for Expanding Artificial Intelligence of Things (AIoT)

Byung Woon Kim, Ga Eun Choi — Thu, 18 Dec 2025 16:34:57 -0800

ABSTRACT

This study analyzes the architecture of the beyond 5G-NTN (Non-terrestrial Network) integrated network and presents the technical, legal, and regulatory challenges and considerations for expanding the Artificial Intelligence of Things (AIoT) ecosystem. 5G-NTN integrates LEO, MEO, and GEO satellite communications with terrestrial networks (Mobile Network Operator, Mobile Virtual Network Operator) to provide global connectivity. Based on the 3GPP Rel-17/18 standards, it incorporates key technologies such as network slicing, edge computing, and dynamic spectrum allocation. To establish a robust AIoT ecosystem, technological solutions such as shared licensing for NTN and terrestrial network spectrum, optimization of network slicing, and QoS-based service differentiation are required. From a legal and regulatory perspective, cooperation with global regulatory bodies such as the ITU, FCC, and MSIT is necessary to establish NTN access models and wholesale policies. Additionally, policies for satellite data security and privacy protection must be developed. Strengthening interoperability between MNOs and Satellite Network Operators (SNOs) and establishing the Satellite Virtual Network Operator (SVNO) model, which includes MVNOs and the private 5G market, is crucial. This study emphasizes that the 5G-NTN-based AIoT ecosystem will serve as a key infrastructure driving future digital innovation and provides practical insights for policymakers, telecom operators, and research institutions. The global AIoT economy is projected to reach $411.5 billion by 2040, necessitating technical standardization and regulatory support to sustain its growth. Importantly, slicing must also be understood as a business model, involving SLA agreements and value chain optimization between SNOs and Mobile Network Operators (MNOs).

Self‐Healing Swarm Beamforming for LEO Satellite Constellations

W. Belgacem, N. Belgacem — Tue, 16 Dec 2025 18:34:11 -0800

ABSTRACT

Low Earth Orbit (LEO) satellite constellations must be able to communicate reliably, strongly, and with little energy use in order to meet 5G/6G performance goals. This paper introduces Self-Healing Swarm Beamforming (SHSB), a new way to do distributed beamforming. SHSB lets adaptive digital beamforming happen across the whole constellation by using federated deep reinforcement learning (FDRL) and topology-aware dynamic antenna arrays. SHSB creates a virtual massive multiple-input multiple-output (MIMO) array by treating satellites as a cooperative swarm. This increases signal-to-interference-plus-noise ratio (SINR), lowers energy use, and improves spatial coverage. Reconfigurable intelligent surfaces (RIS) make beam directivity even better at 28 GHz. In case of a satellite failure, a predictive self-healing mechanism reallocates beams within five seconds. It uses graph neural networks (GNNs) to predict topology, which fills in gaps in the previous FDRL-RIS methods that focused on energy but did not have resilient beamforming. SHSB reduces energy consumption by 25%, delivers SINR >$$ > $$ 18 dB at 16-dB SNR, and achieves a spectral efficiency of 120 bits/s/Hz at 20-dB SNR, according to MATLAB simulations. The feasibility is confirmed by theoretical limits on FDRL convergence and system stability. For next-generation satellite networks, SHSB provides a scalable, autonomous, and high-capacity solution with direct applications in disaster recovery, Internet of Things (IoT) connectivity, and international broadband services. This study proposes Self-Healing Swarm Beamforming (SHSB), a distributed framework integrating federated deep reinforcement learning (FDRL), reconfigurable intelligent surfaces (RIS), and graph neural network (GNNs) for resilient Low Earth Orbit (LEO) satellite communications. This work enables predictive self-healing with beam reallocation in less than 5 s upon satellite failure, ensuring constellation-wide topology adaptation. This research forms virtual massive multiple-input multiple-output (MIMO) arrays via swarm coordination, achieving SINR >18 dB at 16-dB SNR and spectral efficiency of 120 bits/s/Hz at 20-dB SNR. This work demonstrates 25% energy reduction compared to centralized DBF baselines through MATLAB simulations with 100 Monte Carlo runs under Ricean fading. This study provides theoretical convergence bounds for FDRL and stability proofs, affirming scalability for 5G/6G applications in disaster recovery and Internet of Things (IoT).

Sparse Channel Recovery in LEO Satellite–UAV Networks Using Centralized Cooperative CS

Ahmed Moumena — Fri, 12 Dec 2025 18:04:32 -0800

ABSTRACT

The combination of low Earth orbit (LEO) satellite constellations and unmanned aerial vehicle (UAV) fleets represents a revolutionary structure for future communication systems, providing widespread connectivity and improved operational adaptability. Nevertheless, the considerable mobility of LEO satellites brings about notable Doppler shifts, and the air-to-ground communication channel is naturally limited, posing a crucial obstacle in accurately and effectively estimating the channel. This study explores a centralized cooperative compressed sensing (CS) framework in order to effectively tackle this particular challenge. We conduct a simulation of a network in which multiple UAVs work together to sense a sparsely populated communication channel from a LEO satellite. Every UAV obtains a limited set of compressed measurements and transmits them to a central controller. This controller consolidates the measurements and utilizes the orthogonal matching pursuit (OMP) algorithm to simultaneously reconstruct the high-dimensional channel impulse response. The simulation carried out in the MATLAB software models a practical scenario involving cooperative UAVs and noncooperative UAVs, a channel of specific length with sparsity, and includes the Doppler effect arising from a LEO satellite communicating in the S-band. The findings illustrate the effectiveness of the collaborative method in attaining a precise channel reconstruction with a low normalized mean squared error (NMSE). The examination validates that through combining measurements taken at a rate below the Nyquist limit, the network can effectively address the limited sampling capabilities of each UAV. This results in a resilient and precise reconstruction of the sparse channel structure. Communication throughput in dynamic systems involving LEO and UAV technology. This study confirms the capacity of collaborative CS as a fundamental technology enabling efficient, high-capacity communication in dynamic LEO-UAV systems.

Design and Performance Analysis of Multisatellite Cooperative Transmission Based on Orthogonal Carrier Aggregation

Fri, 05 Dec 2025 00:00:00 -0800

ABSTRACT

With the continuous growth of satellite communication traffic and user access demands, the limited bandwidth capacity of a single satellite is insufficient to support the scalable broadband access demands of video services. To address this challenge, this paper proposes a multisatellite cooperative distributed orthogonal carrier aggregation (CA). By dynamically allocating satellite spectrum resources to orthogonal subcarriers and combining signals at the ground terminal, the system bandwidth is significantly enhanced. Employing a guard-interval-free design, the scheme relies on precise synchronization and Doppler precompensation to achieve seamless orthogonal CA, effectively avoiding spectrum waste, suppressing interference, and maximizing spectral efficiency. In response to the key technical challenges in cooperative transmission, this paper focuses on studying symbol timing synchronization and frequency synchronization algorithms for multilink scenarios. To validate the practical performance of the scheme, a dual-satellite cooperative transmission simulation system with a signal bandwidth of 5 MHz was established, and QPSK modulation was adopted for testing. Simulation results demonstrate that at a bit error rate (BER) of 10⁻³, the signal-to-noise ratio (SNR) gains under ideal synchronization conditions (without timing and frequency impairments) reach 3 and 2.7 dB in AWGN and NTN-TDL-D channels, respectively. Even when channel impairments such as Doppler frequency offset and link delay are introduced, the system still maintains SNR gains of 2.75 and 2.5 dB after precompensation at the transmitter based on the proposed algorithm. These results significantly validate the effectiveness and robustness of the proposed scheme in complex satellite-terrestrial communication scenarios.

Digital Twin‐Based Optimization of Service Availability in LEO Mega Constellations Considering Handover Delays in Open RAN

Siva Satya Sri Ganesh Seeram, Luca Feltrin, Mustafa Ozger, Cicek Cavdar — Thu, 04 Dec 2025 20:30:25 -0800

ABSTRACT

As non-terrestrial networks (NTNs) become integral to future 6G systems, ensuring seamless connectivity and service continuity over low Earth orbit (LEO) satellite constellations is essential. This work investigates the impact of open radio access network (RAN) functional splits on handover performance in NTNs, focusing on minimizing service interruptions. We propose effective service time as a novel availability metric that accounts for end-to-end conditional handover (CHO) delay, radio link failures (RLFs), coverage gaps, and constellation-specific propagation dynamics—factors often simplified or ignored. Unlike baseline models that assume ideal, instantaneous switching with no protocol delays or topology changes, our CHO mode reflects 3GPP-compliant, real-world constraints. Leveraging a digital twin-based satellite handover framework, we evaluate availability across multiple constellations, geographic regions, and Open RAN architectures (gNB onboard, Split 2, and Split 7.2x). Results reveal that increasing satellite density beyond a threshold yields diminishing returns, as denser constellations suffer more frequent handovers and higher downtime. For instance, a medium-density constellation with lower altitude achieves an average of 11 min of daily downtime, which rises to 13–16 min under a denser deployment. In contrast, a higher altitude but sparser constellation provides only 5–7 min of downtime, benefiting from fewer handovers. Our analysis revealed that the claim of 99.9%$$ 99.9\% $$ availability in LEO is impractical, where we demonstrated that maximum 99.2%$$ 99.2\% $$ can be achieved with lower altitude constellations. Moreover, functional splits impact performance: Transitioning from gNB onboard to Split 7.2x can reduce availability from say about 99%$$ 99\% $$– 98.5%$$ 98.5\% $$. Finally, we construct a four-dimensional suitability map to identify optimal constellation–architecture pairings across a variety of service requirements defined by delay, modulation, reliability, and availability. Notably, stringent 50-ms delay requirements are not supported by higher altitude constellations despite their higher availability, whereas lower altitude constellations can satisfy them. This study provides valuable insights into NTN design, highlighting the interplay between satellite constellation, network architecture, and service-level guarantees.

Estimating Rain‐Specific Attenuation at Extremely High Frequencies From Disdrometer Measurements at Various Climate Zones in the US

Eugene S. Hong, George Brost, Nicholas Tarasenko, Steven A. Lane — Wed, 03 Dec 2025 00:15:23 -0800

ABSTRACT

The raindrop size distribution (DSD) plays an essential role in understanding rain attenuation effects at extremely high frequencies (EHFs). Over 1 year of DSD measurements was taken at different Köppen–Geiger climate classifications within the United States. Optical disdrometers from Thies Clima were used to measure both the size and velocity of rain droplets. Rain-specific attenuation estimates at various frequencies and rain rates below 40 mm/h were obtained and compared across the multiple locations. Results show that the International Telecommunication Union (ITU) model (ITU-R P.838) generally falls near the median of results across multiple locations; however, the wide variance across the locations demonstrates that no single DSD or rain attenuation model can universally characterize rain attenuation at EHFs. This study provides valuable insights for designers of millimeter-wave communication systems, helping them predict rain attenuation across various climate zones in the US.

Generative Semantic Communication for Efficient Utilization of Satellite Resources in 6G

Hyein Lee, Sooyoung Kim, Heewook Kim, Jihong Park, Jinho Choi, Daesub Oh — Tue, 02 Dec 2025 23:52:40 -0800

ABSTRACT

In this paper, a two-stage resource allocation framework is proposed for generative semantic communication (GSC)–enabled multibeam satellite systems. By integrating semantic compression and generative artificial intelligence, GSC enables efficient downlink transmission by allowing users to reconstruct content from compressed semantic prompts. The proposed framework jointly optimizes the selection of generative cells and generative user ratios as well as bandwidth and power allocation through a multiobjective optimization problem. To reduce complexity, a constrained subset search method and a pruning-based strategy are introduced, achieving near-optimal performance with significantly reduced computation compared with exhaustive search. Simulation results show that the proposed method outperforms conventional ones without GSC in terms of success rate, and goodput under moderate-to-heavy traffic demand, underscoring GSC's potential for a wide range of satellite-based applications, including disaster relief, defense, autonomous driving, and large-scale extended reality.