• Title/Summary/Keyword: constellation design

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Design of Regional Coverage Low Earth Orbit (LEO) Constellation with Optimal Inclination

  • Shin, Jinyoung;Park, Sang-Young;Son, Jihae;Song, Sung-Chan
    • Journal of Astronomy and Space Sciences
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    • v.38 no.4
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    • pp.217-227
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    • 2021
  • In this study, we describe an analytical process for designing a low Earth orbit constellation for discontinuous regional coverage, to be used for a surveillance and reconnaissance space mission. The objective of this study was to configure a satellite constellation that targeted multiple areas near the Korean Peninsula. The constellation design forms part of a discontinuous regional coverage problem with a minimum revisit time. We first introduced an optimal inclination search algorithm to calculate the orbital inclination that maximizes the geometrical coverage of single or multiple ground targets. The common ground track (CGT) constellation pattern with a repeating period of one nodal day was then used to construct the rest of the orbital elements of the constellation. Combining these results, we present an analytical design process that users can directly apply to their own situation. For Seoul, for example, 39.0° was determined as the optimal orbital inclination, and the maximum and average revisit times were 58.1 min and 27.9 min for a 20-satellite constellation, and 42.5 min and 19.7 min for a 30-satellite CGT constellation, respectively. This study also compares the revisit times of the proposed method with those of a traditional Walker-Delta constellation under three inclination conditions: optimal inclination, restricted inclination by launch trajectories from the Korean Peninsula, and inclination for the sun-synchronous orbit. A comparison showed that the CGT constellation had the shortest revisit times with a non-optimal inclination condition. The results of this analysis can serve as a reference for determining the appropriate constellation pattern for a given inclination condition.

Constellation Multi-Objective Optimization Design Based on QoS and Network Stability in LEO Satellite Broadband Networks

  • Yan, Dawei;You, Peng;Liu, Cong;Yong, Shaowei;Guan, Dongfang
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.3
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    • pp.1260-1283
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    • 2019
  • Low earth orbit (LEO) satellite broadband network is a crucial part of the space information network. LEO satellite constellation design is a top-level design, which plays a decisive role in the overall performance of the LEO satellite network. However, the existing works on constellation design mainly focus on the coverage criterion and rarely take network performance into the design process. In this article, we develop a unified framework for constellation optimization design in LEO satellite broadband networks. Several design criteria including network performance and coverage capability are combined into the design process. Firstly, the quality of service (QoS) metrics is presented to evaluate the performance of the LEO satellite broadband network. Also, we propose a network stability model for the rapid change of the satellite network topology. Besides, a mathematical model of constellation optimization design is formulated by considering the network cost-efficiency and stability. Then, an optimization algorithm based on non-dominated sorting genetic algorithm-II (NSGA-II) is provided for the problem of constellation design. Finally, the proposed method is further evaluated through numerical simulations. Simulation results validate the proposed method and show that it is an efficient and effective approach for solving the problem of constellation design in LEO satellite broadband networks.

Space Mission Design For Reconnaissance Micro-Satellite Constellation Using Sun Synchronous-Ground Repeating Orbit (태양동기-지상반복 궤도를 활용한 군 정찰용 초소형 위성군 설계)

  • Cho, Sungmin;Cho, Namsuk
    • Journal of the Korea Institute of Military Science and Technology
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    • v.23 no.2
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    • pp.125-138
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    • 2020
  • One of the most important steps to consider in utilizing micro-satellites for surveillance or reconnaissance operations is the design of the satellite constellation. The Walker-Delta constellation which is commonly used in designing satellite constellations is not ideal for this operation in which military satellites are required to monitor specific regions continuously in a stable manner. This study aims to discuss the methodology for designing a satellite constellation that is capable of monitoring the fixed region at the fixed time each day by using the Sun synchronous Orbit. The BB(Beach Ball) constellation that we propose outperforms the Walker-Delta constellation in terms of robustness and it holds the merit of being simple in its design, thereby making future expansions more convenient. We expect the BB constellation will have a high applicability as the operational concept of military surveillance satellites is established in the near future.

Optimum Design of an SAR Satellite Constellation Considering the Revisit Time Using a Genetic Algorithm

  • Kim, Yunjoong;Kim, Mingu;Han, Bumku;Kim, Youdan;Shin, Hohyun
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.2
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    • pp.334-343
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    • 2017
  • The optimum design of an SAR (Synthetic Aperture Radar) satellite constellation is developed herein using a genetic algorithm. The performance of Earth observations using a satellite constellation can be improved by minimizing the maximum revisit time. Classical orbit design using analytic methods has limitations when addressing orbit dynamics due to various disturbances. To overcome this issue, an optimization technique based on a genetic algorithm is used. STK (Systems Tool Kit) is utilized to propagate the satellite orbit when considering external disturbances, and the maximum revisit time on the earth observation area is calculated. By minimizing the performance index using a genetic algorithm, the optimum orbit of the satellite constellation is designed. Numerical results are provided to demonstrate the performance of the proposed method.

Design of Micro-Satellite Constellation for Reconnaissance of Korean Peninsula (한반도 감시·정찰을 위한 초소형 위성군 설계)

  • Shin, Jinyoung;Hwang, Youngmin;Park, Sang-Young;Jeon, Soobin;Lee, Eunji;Song, Sung-Chan
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.50 no.6
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    • pp.401-412
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    • 2022
  • In this study, we investigated the design methods of satellite constellations to conduct near-real-time surveillance reconnaissance of the Korean Peninsula. Also, we designed satellite constellations utilizing the Walker-Delta method and repeat-ground-track method, and taking into account the target area and the feasible number of satellites. The constrains of the Electro-Optical and Synthetic Aperture Radar equipment were also considered in performance analysis. As a result, the designed constellation has mean revisit time of less than 30 min which enables near-real-time surveillance reconnaissance of the Korean Peninsula. This research provides the strategy to design the satellite constellation for reconnaissance. Furthermore, it contributes to suggesting an operating strategy for micro-satellites constellation and guidelines for establishing space force.

Design of SAR Satellite Constellation Configuration for ISR Mission (ISR 임무를 위한 SAR 위성의 군집궤도 배치형상 설계)

  • Kim, Hongrae;Song, Sua;Chang, Young-Keun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.45 no.1
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    • pp.54-62
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    • 2017
  • For the Earth observation satellite for ISR mission, a satellite constellation can be utilized to observe a specific area periodically and ultimately increase the effectiveness of the mission. The Walker-Delta method was applied to design constellation orbits with four satellites, which could detect abnormal activities in AoI(Area of Interest). To evaluate the effectiveness of the mission, a revisiting time was selected as a key requirement. This paper presents the mission analysis process for four SAR satellites constellation as well as the result of constellation configuration design to meet the requirements. Figure of Merits analysis was performed based on algorithm developed. Finally, it was confirmed that the constellation orbit with four different orbital planes is likely to be appropriate for ISR mission.

A New Design of Signal Constellation of the Spiral Quadrature Amplitude Modulation (나선 직교진폭변조 신호성상도의 새로운 설계)

  • Li, Shuang;Kang, Seog Geun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.24 no.3
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    • pp.398-404
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    • 2020
  • In this paper, we propose a new design method of signal constellation of the spiral quadrature amplitude modulation (QAM) exploiting a modified gradient descent search algorithm and its binary mapping rule. Unlike the conventional method, the new method, which uses and the constellation optimization algorithm and the maximum number of iterations as a parameter for the iterative design, is more robust to phase noise. And the proposed binary mapping rule significantly reduces the average Hamming distance of the spiral constellation. As a result, the proposed spiral QAM constellation has much improved error performance compared to the conventional ones even in a very severe phase noise environment. It is, therefore, considered that the proposed QAM may be a useful modulation format for coherent optical communication systems and orthogonal frequency division multiplexing (OFDM) systems.

Low PAPR CIOD for the Rotated Square QAM Constellation (회전 변환 정사각 신호 성좌에 적용한 낮은 PAPR의 CIOD 전송방식)

  • Kim, Chang-Joong;Lee, Ho-Kyoung
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.49 no.8
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    • pp.65-69
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    • 2012
  • We introduce a rotated square QAM constellation with low peak-to-average-power ratio (PAPR) for coordinate interleaved orthogonal design (CIOD). The proposed signal constellation has much lower PAPR than the ordinary square QAM constellations for CIOD while it keeps almost the same coordinate product distance (CPD).

Design of a New 3-D 16-ary Signal Constellation with Constant Envelope (상진폭 특성을 가지는 새로운 3차원 16진 신호성상도의 설계)

  • Choe, Chae-Cheol;Kang, Seog-Geun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.10
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    • pp.2149-2156
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    • 2011
  • In this paper, design of a new 3-dimensional (3-D) 16-ary signal constellation with constant envelope is presented and analyzed. Unlike the conventional 16-ary constellations, all signal points of the new constellation are uniformly located on the surface of a sphere so that they have a unique amplitude level and a symmetrical structure. When average power of the constellations is normalized, the presented 16-ary constellation has around 11.4% increased minimum Euclidean distance (MED) as compared to the conventional ones that have non-constant envelope. As a result, a digital communication system which exploits the presented constellation has 1.2dB improved symbol error rate (SER). While signal points of the conventional constant-envelope constellation are not distributed uniformly on the surface of a sphere, those of the proposed constellation has a completely symmetric distribution. In addition, the new signal constellation has much lower computational complexity for practical implementation than the conventional one. Hence, the proposed 3-D 16-ary signal constellation is appropriate for the application to a communication system which strongly requires a constant-envelope characteristic.

Design of Multi-Constellation and Multi-Frequency GNSS SDR with Fully Reconfigurable Functionality

  • Song, Young-Jin;Lee, Hak-beom;Won, Jong-Hoon
    • Journal of Positioning, Navigation, and Timing
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    • v.10 no.2
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    • pp.91-102
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    • 2021
  • In this paper, a fully reconfigurable Software Defined Radio (SDR) for multi-constellation and multi-frequency Global Navigation Satellite System (GNSS) receivers is presented. The reconfigurability with respect to the data structure, variability of signal and receiver parameters, and receiver's internal functionality is presented. The configuration file, that is modified to lead to an entirely different operation of the SDR in response to specific target signal scenarios, directly determines the operating characteristics of the SDR. In this manner, receiver designers can effectively reduce the effort to develop many different combinations of multi-constellation and/or multi-frequency GNSS receivers. Finally, the implementation of the presented fully reconfigurable SDR is included with the experimental processing results such as acquisition, tracking, navigation for the received signals in the realistic fields.