Dynamic Network Formation for FSO Satellite Communication

Satellite network optimization is essential, particularly since the cost of manufacturing, launching and maintaining each satellite is significant. Moreover, classical communication optimization methods, such as Minimal Spanning Tree, cannot be applied directly in dynamic scenarios where the satellite constellation is constantly changing. Motivated by the rapid growth of the Star-Link constellation that, as of Q4 2021, consists of over 1600 operational LEO satellites with thousands more expected in the coming years, this paper focuses on the problem of constructing an optimal inter-satellite (laser) communication network. More formally, given a large set of LEO satellites, each equipped with a fixed number of laser links, we direct each laser module on each satellite such that the underlying laser network will be optimal with respect to a given objective function and communication demand. In this work, we present a novel heuristic to create an optimal dynamic optical network communication using an Ant Colony algorithm. This method takes into account both the time it takes to establish an optical link (acquisition time) and the bounded number of communication links, as each satellite has a fixed amount of optical communication modules installed. Based on a large number of simulations, we conclude that, although the underlying problem of bounded-degree-spanning-tree is NP-hard (even for static cases), the suggested ant-colony heuristic is able to compute cost-efficient solutions in semi-real-time.

On the Security of LEO Satellite Communication Systems: Vulnerabilities, Countermeasures, and Future Trends

<div>In view of the development status of the security of LEO satellite communication system, a comprehensive review, induction, and summary is carried out.<br></div>

Virtualized High Throughput Satellite Gateway with a Global Bandwidth Management Method

With the development of new satellite payload technology, in order to improve the utilization of system resources, research is based on software-defined network (SDN) and network function virtualization (NFV) gateway architecture. Based on this architecture, the system realizes global resource management and overall data distribution, which can solve the problem of resource allocation and maximum/minimum rate guarantee between different VNO terminals under different beams, different gateways, and different satellites. For this, a global bandwidth management method can be used which is mainly a process of management to control the traffic on a communication link. The proposed global resource management and control method can be based on the rate guarantee value of the VNO/terminal configured in the system as the basic limiting condition and reallocate the rate guarantee value limiting parameter according to the resource application status of the online terminal. The method can maximize the resource utilization of the entire satellite communication system and satisfy the resource request of the user terminal as much as possible.

On the Security of LEO Satellite Communication Systems: Vulnerabilities, Countermeasures, and Future Trends

<div>In view of the development status of the security of LEO satellite communication system, a comprehensive review, induction, and summary is carried out.<br></div>

Effectiveness Evaluation Method of Constellation Satellite Communication System with Acceptable Consistency and Consensus Under Probability Hesitant Intuitionistic Fuzzy Preference Relationship

System effectiveness evaluation is an important part of constellation satellite communication system research, with applications in project verification and optimization as well as tactical and technical measurement argumentation. This paper presents a systematic and comprehensive effectiveness evaluation method for a constellation satellite communication system under a probabilistic hesitant intuitionistic fuzzy preference relationship (PHIFPR), aiming to better address the fuzziness and uncertainty in effectiveness evaluation. First, a proposed definition of PHIFPR describes the hesitancy of evaluators, provides hesitancy distribution information, and depicts the worst negative information and risk preferences in effectiveness evaluation. Then, we deduce the approximate consistency index of PHIFPR and establish a mathematical programming model to increase individual consistency when the approximate consistency index does not reach a predetermined level. In the sequel, a proposed group consensus index uses the PHIFPR-based Hausdorff distance to measure the closeness between evaluators' judgements. Afterwards, a consistency and consensus improvement model is designed to retain the original opinions of evaluators to make the consistency and consensus of PHIFPRs acceptable. Moreover, a goal programming model is established to gain the reliable scheme priority weights by regarding the approximate consistency condition of a PHIFPR as a fuzzy constraint. Finally, an experimental example is offered to highlight the practicability and feasibility of the proposed method, and some comparative analyses with other methods offer insights into the designed method.

Modeling and Fabrication of a Reconfigurable RF Output Stage for Nanosatellite Communication Subsystems

Current small satellite platforms such as CubeSats require robust and versatile communication subsystems that allow the reconfiguration of the critical operating parameters such as carrier frequency, transmission power, bandwidth, or filter roll-off factor. A reconfigurable Analog Back-End for the space segment of a satellite communication subsystem is presented in this work. This prototype is implemented on a 9.5 cm2 6-layer PCB, and it operates from 0.070 to 6 GHz and complies with CubeSat and IPC-2221 standards. The processing, control, and synchronizing stages are carried out on a Software-Defined Radio approach executed on a baseband processor. Results showed that the signal power at the output of the proposed Analog Back-End is suitable for feeding the following antenna subsystem. Furthermore, the emitted radiation levels by the transmission lines do not generate electromagnetic interference.

Communication satellite resource scheduling based on improved whale optimization algorithm

Under the background of increasing pressure of satellite communication support, reasonable and efficient dispatch of communication satellite resources is an important means to improve the utilization efficiency of communication resources. Aiming at the resource scheduling task requirements of geostationary orbit communication satellite system, communication satellite resource scheduling (CSRS) model is established first of all, based on this, advances a kind of CSRS method based on improved whale optimization algorithm. In this method, the detection and search strategy is proposed and the crossover mutation operator is used to avoid the algorithm falling into local optimum. Simulation results show that IWOA can effectively improve the quality and stability of satellite resource scheduling.

Analysis of key technologies for creating multisatellite orbital constellations of small spacecraft

One of the key areas of modern world cosmonautics is the development of cluster space systems for various purposes, consisting of a large number of functioning spacecraft. This became possible due to a decrease in the mass of spacecraft due to the creation and use of new materials, the development of electronics and microelectromechanical systems, the use of the group launch method, the development of multi-agent technologies and inter-satellite communication sys-tems. There are projects of systems consisting of a large number of space objects, such as OneWeb, Planet, Starlink, Satellogic, etc. The main classes of devices used to create such multi-satellite systems are small satellites, including the number of micro (up to 100 kg) and nano (up to 10-15 kg) classes, which have significant advantages over heavy space-craft, especially in terms of the timing and cost of their creation. The deployment of multi-satellite constellations, in-cluding hundreds and thousands of satellites, requires fundamentally new approaches to the creation of spacecraft and the system as a whole at all stages of the life cycle. The article discusses the key technologies used to create multi-satellite orbital constellations based on small satellites at different stages of the life cycle - from the early stages of de-sign to the stage of operation and disposal (information from orbit). The experience of a joint project of Samara Univer-sity and the Progress Rocket and Space Center on the creation of a constellation of small spacecraft of the AIST series is presented.

Load Balancing Routing Algorithm of Low-Orbit Communication Satellite Network Traffic Based on Machine Learning

Satellite communication has become an important research trend in the field of communication technology. Low-orbit satellites have always been the focus of extensive attention by scholars due to their wide coverage, strong flexibility, and freedom from geographical constraints. This article introduces some technologies about low-orbit satellites and introduces a routing algorithm DDPG based on machine learning for simulation experiments. The performance of this algorithm is compared with the performance of three commonly used low-orbit satellite routing algorithms, and a conclusion is drawn. The routing algorithm based on machine learning has the smallest average delay, and the average value is 126 ms under different weights. Its packet loss rate is the smallest, with an average of 2.9%. Its throughput is the largest, with an average of 201.7 Mbps; its load distribution index is the smallest, with an average of 0.54. In summary, the performance of routing algorithms based on machine learning is better than general algorithms.