Inter-satellite Communication Research Articles

Average bit-error rate analysis of an inter-satellite optical communication system under the effect of perturbations

Average bit-error rate analysis of an inter-satellite optical communication system under the effect of perturbations

Enabling high-speed and large-capacity data transmission in optical inter-satellite communication links under various conditions

Enabling high-speed and large-capacity data transmission in optical inter-satellite communication links under various conditions

A 4 × 20 Gbps inter-satellite optical wireless communication system based on orbital angular momentum multiplexing: performance evaluation

A 4 × 20 Gbps inter-satellite optical wireless communication system based on orbital angular momentum multiplexing: performance evaluation

Hierarchical agglomerative clustering approach for direct and obstructed link classification in IsOWC systems

A novel. to the best of our knowledge, technique based on hierarchical agglomerative clustering (HAC) is proposed to classify the direct and obstructed links in intersatellite optical wireless communication (IsOWC) systems. Prior to the training phase, an exploratory data analysis and preprocessing technique are conducted on a dataset composing 250 instances with four unlabeled input features: relative intensity noise, propagation distance, pointing error, and insertion loss. These datasets extract from IsOWC systems utilizing on-off keying modulation. The HAC technique demonstrates exceptional performance, achieving a classification accuracy of 92.7%, surpassing other machine learning techniques. Additionally, the impact of input feature combinations is discussed in detail using dendrogram plots and various performance metrics. The results provide valuable insights for localizing satellite constellations in earth orbit and advancing global Internet accessibility.

Active phase locking of a three-aperture array using a corner cube lateral transfer reflector

We present a novel technique for coherent beam combining of a three-aperture array. In our method, a retroreflector samples the beam from the edge of each aperture and redirects the sampled beams back through the gap in the center. The sampled beams contain both angle and phase information for the three-aperture array, which can be used to lock the phase and tip/tilt. In a proof-of-concept experiment, we phase-lock the three-aperture array by maximizing the power through a pin hole of the far-field pattern of the sampled array via the stochastic parallel gradient descent algorithm. This approach eliminates the need for bulky sampling optics, which is particularly advantageous for the large-diameter arrays required for long distance inter-satellite free-space optical communication.

Analysis of inter-satellite optical wireless communication systems for enhanced data transmission in satellite constellations

This research focuses on the comprehensive performance analysis of inter-satellite optical wireless communication (IsOWC) systems, specifically tailored for high data rate applications in Earth observation satellites. The research employs OptiSystem 21.0 simulation software to model and analyze the IsOWC systems. The simulation scenario is set in a low Earth orbit (LEO) constellation, typical for Earth observation satellites. Various system parameters are systematically varied to assess their impact on performance. Modulation types, such as non-return-to-zero (NRZ) and return-to-zero (RZ) are analyzed for their influence on the quality (Q) factor. The study further explores the effects of different wavelengths, antenna apertures, transmitter output powers, and link distances on the IsOWC system performance. This research provides valuable insights into optimizing IsOWC systems for Earth observation satellites, contributing to the advancement of communication technologies in satellite networks. The research shows that the NRZ modulation consistently outperforms RZ modulation in terms of maximum Q factor and minimum BER across different antenna apertures and power levels. Additionally, shorter wavelengths exhibit improved performance, while larger antenna apertures contribute to enhanced signal quality. The relationship between transmitter power and data rate is also investigated, demonstrating the potential for achieving higher data rates with increased transmitter power. The findings guide the selection of parameters to achieve optimal performance, ensuring efficient data transfer and meeting the demands of contemporary Earth observation missions. This study provides conclusive evidence that the 1350 nm wavelength outperforms the 1550 nm wavelength in reliable and high-data-rate optical wireless communications, offering higher received power, superior signal quality, and lower bit error rates. This makes it a preferred choice for systems in challenging space environments and could enhance future satellite communication architectures.

A Flexible Topology Control Strategy for Mega-Constellations via Inter-Satellite Links Based on Dynamic Link Optimization

In large-scale satellite constellations, the efficiency of inter-satellite communication is paramount. Traditional topology control strategies, such as the Manhattan configuration, provide stable links but can result in indirect communication paths, affecting the efficiency of information transfer. This paper addresses this issue by proposing an innovative “3 + 1” dynamic topology control scheme. The scheme retains three static links determined by the relative angular velocity and acceleration while introducing a dynamic link based on distance and angular velocity constraints to optimize the link duration and overall network communication efficiency. To address the complexity of matching dynamic links, this paper introduces an elite strategy-based maximum weighted matching algorithm for general graphs. Compared to traditional greedy algorithms, our proposed algorithm significantly improves the link duration and topological stability. Through simulation experiments comparing communication delays between Xiamen and Los Angeles, our results show that the proposed dynamic link scheme substantially reduces the average delay, enhancing the efficiency and flexibility of inter-satellite communication. This research not only extends the duration of inter-satellite links but also provides new perspectives and methodologies for further studies on inter-satellite topology control strategies.

Satellite-based entanglement distribution and quantum teleportation with continuous variables

Advances in satellite quantum communications aim at reshaping the global telecommunication network by increasing the security of the transferred information. Here, we study the effects of atmospheric turbulence in continuous-variable entanglement distribution and quantum teleportation in the optical regime between a ground station and a satellite. More specifically, we study the degradation of entanglement due to various error sources in the distribution, namely, diffraction, atmospheric attenuation, turbulence, and detector inefficiency, in both downlink and uplink scenarios. As the fidelity of a quantum teleportation protocol using these distributed entangled resources is not sufficient, we include an intermediate station for either state generation, or beam refocusing, in order to reduce the effects of atmospheric turbulence and diffraction, respectively. The results show the feasibility of free-space entanglement distribution and quantum teleportation in downlink paths up to the LEO region, but also in uplink paths with the help of the intermediate station. Finally, we complete the study with microwave-optical comparison in bad weather situations, and with the study of horizontal paths in ground-to-ground and inter-satellite quantum communication.

A Lightweight Broadband Circularly Polarized Stacked Patch Antenna Formed by Meshed Aluminum Disks for Inter-Satellite Communication

A Lightweight Broadband Circularly Polarized Stacked Patch Antenna Formed by Meshed Aluminum Disks for Inter-Satellite Communication

Channel Modeling Based on Transformer Symbolic Regression for Inter-Satellite Terahertz Communication

Channel modeling is crucial for inter-satellite terahertz communication system design. The conventional method involves manually constructing a mathematical channel model, which is labor-intensive, and using a neural network directly as a channel model lacks interpretability. This paper introduces a channel modeling approach based on symbolic regression. It is the first time that using transformer neural networks as the implementation tool of symbolic regression to generate the mathematical channel model from the channel data directly. It can save manpower and avoid the interpretability issue of using neural networks as a channel model. The feasibility of the proposed method is verified by generating a free space path loss model from simulation data in the terahertz frequency band.

Constellation design for PD-NOMA-based mmWave inter-satellite communication

The upcoming sixth-generation (6G) networks are supposed to utilize frequencies beyond the fifth-generation (B5G) and serve for satellite communications. During inter-satellite millimeter wave (mmWave) communications, the transmitting satellites may have identical simultaneous power transmissions, leading to the erroneous decoding of their information. This paper describes the application of a power-domain (PD) non-orthogonal multiple-access (NOMA) scheme for both terrestrial and inter-satellite communications consisting of two users or satellites. Specifically, the user (or satellite) symbol decoding is addressed under identical power transmissions. Both the user’s (transmitting satellite’s) data are extracted by minimizing the average probability of symbol errors using a designed constellation. Analytical/graphical results along with the simulation verify decent symbol decoding at a low average noise variance. At a noise variance of 0.01, the achieved average symbol-error probability reaches an order of up to 10−5. The proposed system results in a negligible error-vector magnitude (EVM) of −10 dB at higher end of the considered signal-to-interference-plus-noise ratio (SINR) range. Further, the proposed method alleviates the successive interference cancellation (SIC) pre-requisite of NOMA, strengthening the application of NOMA with mmWaves in next-generation satellite communication systems.

Large-volume LEO satellite imaging data networked transmission scheduling problem: Model and algorithm

With the current miniaturization and cost reduction trend, many small imaging satellites are deployed in low Earth orbit (LEO). Efficient scheduling of transmission links is crucial for handling the large volume of imaging data in the time-varying inter-satellite broadband communication networks. This ensures optimal utilization of inter-satellite link resources and gives rise to a novel problem known as the Large-volume LEO satellite Imaging Data Networked Transmission Scheduling Problem (LLSIDNTSP). This problem requires the integrity of the imaging data received on the ground station. A Specific Time-Evolving Graph (STEG) model is introduced to formulate this problem, while a highly effective Sequential Two-Phased Heuristic Algorithm (STPHA) is proposed to solve it. STPHA determines an optimized Contact Plan (CP) with a Contact-Fast Construction Algorithm (CFCA) in the first phase. With this CP as input, it produces an optimal transmission schedule with Linear Programming in the second phase. The CFCA incorporates a novel heuristic called Mission Residual Volume Factor(MRVF), which guides the selection of a proper inter-satellite and satellite-to-ground link at each construction step. Extensive simulation results demonstrate the effectiveness of the proposed STPHA. In particular, it can achieve the optimal solution for small-sized scenarios with one-hundredth of the computing time used by the exact solver CPLEX. Also, it is consistently better than other heuristic algorithms adapted from the literature for large-sized scenarios. Additional experimental analysis is conducted to showcase the effectiveness of the innovative components of STPHA.

In situ plasma and neutral gas observation time windows during a comet flyby: Application to the Comet Interceptor mission

A comet flyby, like the one planned for ESA’s Comet Interceptor mission, places stringent requirements on spacecraft resources. To plan the time line of in situ plasma and neutral gas observations during the flyby, the size of the comet magnetosphere and neutral coma must be estimated well. For given solar irradiance and solar wind conditions, comet composition, and neutral gas expansion speed, the size of gas coma and magnetosphere during the flyby can be estimated from the gas production rate and the flyby geometry. Combined with flyby velocity, the time spent in these regions can be inferred and a data acquisition plan can be elaborated for each instrument, compatible with the limited data storage capacity. The sizes of magnetosphere and gas coma are found from a statistical analysis based on the probability distributions of gas production rate, flyby velocity, and solar wind conditions. The size of the magnetosphere as measured by bow shock standoff distance is 105–106km near 1au in the unlikely case of a Halley-type target comet, down to a nonexistent bow shock for targets with low activity. This translates into durations up to 103–104 seconds. These estimates can be narrowed down when a target is identified far from the Sun, and even more so as its activity can be predicted more reliably closer to the Sun. Plasma and neutral gas instruments on the Comet Interceptor main spacecraft can monitor the entire flyby by using an adaptive data acquisition strategy in the context of a record-and-playback scenario. For probes released from the main spacecraft, the inter-satellite communication link limits the data return. For a slow flyby of an active comet, the probes may not yet be released during the inbound bow shock crossing.

Free space optical communication system: a review of practical constraints, applications, and challenges

Abstract FSO (free space optical) communication holds emanated position in the role of propitious innovation with exorbitant-speed using the data transmission mechanism without the wire, propounding an accomplishable explication to the surging need for bandwidth in communication networks. This research paper probes into the improvements and obstacles in FSO communication systems, pursuing to anticipate a compendious encapsulation of the state-of-the-art establishment in this discipline. The evaluation incorporates a meticulous inspection of vital constituents such as laser sources, modulators, and receivers, elucidating their contribution to accomplishing coherent data transfer. The scrutinizing also investigates innumerable atmospheric circumstances affecting FSO links, including weather conditions and turbulence, and puts forward ingenious approaches to alleviate their repercussion on communication performance. Furthermore, the paper explores the homogenization of ultra-modern signal processing techniques to amplify the credibility and robustness of FSO systems, corroborating seamless communication even in challenging environments. Moreover, the research inquiries into the neoteric experimental framework and real-world execution of FSO communication, shedding light on heuristic contemplation, and substantiating theoretical unearthing. The conclusion of this research shells out treasures perception of the ongoing attempt to optimize FSO communication for variegated applications, including, inter-satellite communication, high-speed internet access, and last-mile connectivity. As FSO perpetuates progress, this paper suffices as a recent and inclusive resource for researchers, engineers, and policymakers maneuvering the edges of optical communication technologies.

Parameter-free fiber coupling method for inter-satellite laser communications based on Gaussian approximation

Satellite constellation networks play a pivotal role in making Beyond 5G services universally accessible to people worldwide. Inter-satellite laser communication is a crucial component of satellite communication networks. To utilize fiber amplifiers, it is imperative to couple the free-space optical beam into a single-mode fiber. However, vibrations and non-coaxial errors significantly impact coupling efficiency, thereby affecting communication quality. We have developed a parameter-free fiber coupling method based on Gaussian approximation to rectify non-coaxial errors and mitigate incident angle deviations induced by vibrations, ensuring consistently high coupling efficiency. This method is fast, stable, and parameter-free, eliminating the need for manual intervention. Furthermore, experimental results demonstrate the method’s effectiveness across the entire correction range of the correction device. In environments with strong vibrations, the communication link experiences a bit error rate of 6.734 E-2, which is reduced to zero bit errors after implementing this method in a closed loop.

Study on Linewidth and Phase Noise Characteristics of a Narrow Linewidth External Cavity Diode Laser.

In the field of inter-satellite laser communication, achieving high-quality communication and compensating for the Doppler frequency shift caused by relative motion necessitate lasers with narrow linewidths, low phase noise, and the ability to achieve mode-hop-free tuning within a specific range. To this end, this paper investigates a novel external cavity diode laser (ECDL) with a frequency-selective F-P etalon structure, leveraging the external cavity F-P etalon structure in conjunction with an auxiliary filter to achieve single longitudinal mode selection. The laser undergoes linewidth testing using a delayed self-heterodyne beating method, followed by the testing of its phase noise and frequency noise characteristics using a noise analyzer, yielding beat spectra and noise power spectral density profiles. Furthermore, the paper introduces an innovative bidirectional temperature-scanning laser method to achieve optimal laser-operating point selection and mode-hop-free tuning. The experimental results showcase that the single longitudinal mode spectral side-mode suppression ratio (SMSR) is around 70 dB, and the output power exceeds 10 mW. Enhancing the precision of the F-P etalon leads to a more pronounced suppression of low-frequency phase noise, reducing the Lorentzian linewidth from the initial 10 kHz level to a remarkable 5 kHz level. The bidirectional temperature-scanning laser method not only allows for the selection of the optimal operating point but also enables mode-hop-free tuning within 160 pm.

On the Design of Broadband Asymmetric Y-Junction Ferrite Circulator for 60-GHz Inter-Satellite Communication

On the Design of Broadband Asymmetric Y-Junction Ferrite Circulator for 60-GHz Inter-Satellite Communication

Transponder-type laser interferometer prototype for spaceborne gravitational wave detectors.

Transponder-type laser interferometry is essential in spaceborne gravitational wave detection missions. This paper presents a transponder-type laser interferometer prototype for potential noise calibration of spaceborne gravitational wave detectors. Using a digital optical phase-locked loop, we successfully locked the phase of the slave laser to the master laser (∼200p W). Once the link between the master laser and the slave laser is established, the two satellites (essentially two lasers) form a transponder-type laser interferometer. We carefully analyze the measurement stability and noise characteristics of the interferometer, and the results show that the Allan deviation of the zero drift can reach 243.2pm at t=0.429s, while the noise spectral density has a typical 1/f line shape with a floor of 21p m/H z 1/2 at 1Hz. The coherence analysis shows that the temperature drift is an important factor limiting the performance of the interferometer below 2mHz, while the frequency noise of the master laser is not dominant in the experiment. Transponder-type laser interferometers have a wide range of applications in intersatellite communication and measurement. Our design can serve as a valuable reference for gravitational wave detection missions such as LISA.

Research on Hopping Routing of Periodic Multiorbit LEO Satellites

In recent years, the low Earth orbit microsatellite network technology has experienced rapid development due to its advantages of low latency, low cost, and short development cycles. However, building an efficient and reliable satellite network routing system faces many challenges due to the characteristics of satellite networks, such as fast‐changing topology, large variations in link latency, higher probabilities of node and link failures, and limited resources. Routing algorithms have a significant impact on intersatellite communication and have become a research hotspot. The current mainstream algorithms focus on reducing information propagation delays between satellites to enable faster transmission. However, many satellite networks, such as meteorological observation satellite networks, are not sensitive to propagation delays but emphasize reducing hardware costs, especially for the receiving and transmitting signal systems of satellites. This means minimizing the single‐step signal transmission distance of satellites. This article proposes a routing algorithm based on time slot planning and the shortest path step length. Experimental simulation results demonstrate that this algorithm significantly reduces the step length of signal transmission and lowers hardware costs.

Research on Inter-Satellite Laser Communication Link Transmission and Routing Switching Technology of Satellite Internet (Invited)

Research on Inter-Satellite Laser Communication Link Transmission and Routing Switching Technology of Satellite Internet (Invited)