저궤도 군집 위성 간 통신 현황 및 주요 기술 동향

차홍설,김종민,임병주,이주형,고영채 한국통신학회 2022 韓國通信學會論文誌 Vol.47 No.10

Traditional satellite communication was limited to specific services such as military communication or broadcasting due to the cost and technical complexity issues. However, thanks to the recent development of satellite launch technology, it is envisaged that future satellite communication supports broadband internet services by deploying tens of thousands of satellites in Low Earth Orbit (LEO). The mega-constellation of the LEO satellite communication system consists of satellite-to-ground communication and satellite-to-satellite communication. In particular, inter-satellite link (ISL) technology for satellite-to-satellite communication is in the early stage, while satellite-to-ground communication technology is relatively mature. Thus, many countries have been getting attention to this ISL technology to accomplish low-latency and high-rate LEO satellite communication. In this paper, we summarize the current status of LEO satellite communication technology, focusing on the ISL technology while providing its future direction. 기존의 위성 시스템들은 통신서비스를 제공하기 위하여 주로 고비용의 정지궤도 위성 시스템을 이용하였기 때문에, 저비용의 이동통신 서비스를 제공하는 데에는 여러 가지 한계점이 존재해 왔다. 그러나 최근 위성 발사 기술발전으로 다수의 위성을 저비용으로 운용할 수 있음에 따라, 위성 통신이 개인 무선통신 서비스까지 지원할 수있을 것으로 전망되고 있다. 특히 저궤도 (Low Earth Orbit, LEO)에 수만 대의 위성을 배치하여 전 지구적 범위로 통신 네트워크를 제공하는 방식이 차세대 통신 분야로 여겨지고 있으며, 이를 LEO 군집 위성 통신 시스템이라고 한다. 해당 LEO 군집 위성 통신 시스템은 크게 위성-지상 간 통신과 위성-위성 간 통신으로 나누어 볼 수있는데, 이미 성숙기에 접어든 위성-지상 간 통신 기술과는 달리, 위성-위성 간 통신 (Inter Satellite Link, ISL) 기술은 선도국인 미국을 포함해 전 세계적으로 아직 태동기이다. ISL 기술은 통신 지연시간을 최소화하고 초고속데이터 통신을 실현하기 위해 필수적인 기술이다. 본 논문에서는 해당 ISL 기술을 구현하기 위한 필수 요소 기술들과 기술 현황을 요약하여 국내 위성 통신 기술 개발에 참고가 되고자 한다.

A Mathematical Model for Optimal Communication Scheduling between Multiple Satellites and Multiple Ground Stations

Eugine Jeong(정유진),Heungseob Kim(김흥섭) 한국산업경영시스템학회 2018 한국산업경영시스템학회지 Vol.41 No.1

In the satellite operation phase, a ground station should continuously monitor the status of the satellite and sends out a tasking order, and a satellite should transmit data acquired in the space to the Earth. Therefore, the communication between the satellites and the ground stations is essential. However, a satellite and a ground station located in a specific region on Earth can be connected for a limited time because the satellite is continuously orbiting the Earth, and the communication between satellites and ground stations is only possible on a one-to-one basis. That is, one satellite can not communicate with plural ground stations, and one ground station can communicate with plural satellites concurrently. For such reasons, the efficiency of the communication schedule directly affects the utilization of the satellites. Thus, in this research, considering aforementioned unique situations of spacial communication, the mixed integer programming (MIP) model for the optimal communication planning between multiple satellites and multiple ground stations (MS-MG) is proposed. Furthermore, some numerical experiments are performed to verify and validate the mathematical model. The practical example for them is constructed based on the information of existing satellites and ground stations. The communicable time slots between them were obtained by STK (System Tool Kit), which is a well known professional software for space flight simulation. In the MIP model for the MS-MG problems, the objective function is also considered the minimization of communication cost, and ILOG CPLEX software searches the optimal schedule. Furthermore, it is confirmed that this study can be applied to the location selection of the ground stations.

Conceptual design of emergency communication system to cope with severe accidents in NPPs and its performance evaluation

Son, Kwang Seop,Kim, Chang Hwoi,Kang, Hyun Gook Elsevier 2015 Annals of nuclear energy Vol.76 No.-

<P><B>Abstract</B></P> <P>The Fukushima accident induced by the great earthquake and tsunami reveals the vulnerability of I&C System. In the severe environment, the normal I&C system did not work properly and results in false information about the internal situation in NPP. Eventually the accident was not properly handled at the early stage. Therefore advanced emergency response system using a wireless channel is necessary to cope with the severe accident. In this paper, we introduce the ERS consisting of the HMS and MCS the ECS linking the HMS with MCS and the performance requirement of the ECS is analyzed. The ECS satisfying the requirement is designed conceptually and the performance of the ECS is evaluated through analysis and simulator. To secure a reliable and diverse configuration, the ECS is configured as the dual system which consists of the terrestrial communication and satellite communication. The terrestrial communication system is designed based on the IEEE 802.11. Analyzed performance results prove that the performance requirement can be sufficiently achieved. But if the scalability of data capacity is considered later, use of the advanced 802.11 standard such as 802.11n and multiple signal paths between the HMS and MCS are necessary. In the satellite communication system, the FDMA is used in the status link and the DSSS is used in the control link. The network supporting various data rates is designed and the communication link budget is analyzed considering the link availability of 99%. The designed satellite communication system can secure the link margin of 1.3–15.7dB.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The emergency communication system requires the performances of the throughput of 1Mbps, BER of 10<SUP>−6</SUP> and network configuration of 1:12 communication. </LI> <LI> The emergency communication system consists of the terrestrial communication and satellite communication system. </LI> <LI> In the terrestrial communication system, at least two wireless repeaters are needed to secure LOS and the throughput and delay time are 16Mbps and 16ms, respectively. </LI> <LI> In the satellite communication system, DSSS and FDMA are used and the fade margin range is from 1.3 to 16dB. </LI> </UL> </P>

Reconfigurable Communication Satellite System "SoftSAT"

Nishinaga, Nozomu,Ogawa, Yasuo,Takayama, Yoshihisa,Takahashi, Takashi,Kubooka, Toshihiro,Hiroaki, Umehara Hanako 통신위성우주산업연구회 2002 Joint Conference on Satellite Communications Vol.2002 No.-

Satellite communications provides characteristics such as wide-area coverage and flexibility of network construction. Since an enormous budget and time are require for satellite development, however, it is difficult to implement the latest techniques onboard. Even of the latest communications technology is implemented at the time of launch, it is impossible to follow paradigm shifts in terrestrial network technology. In this paper, we propose a reconfigurable communication satellite system based on the formation-flight technique and inter-satellite communication technology. This satellite system consists of a group of layered satellites that can operate together like one satellite.

Comparative Study and Performance Analysis of Different Modulation Techniques Relevant to Bangabandhu Satellite Communication System

Md. Sazal Miah,Md. Atiqur Rahman,Zabid Ahmed,Yeonggwang Kim,Jinsul Kim 한국디지털콘텐츠학회 2020 The Journal of Contents Computing Vol.2 No.1

Satellite communication assumes a crucial job in the innovative advancement of a nation. Being the nation"s first communications satellite, Bangabandhu Satellite-1 (BS-1) is considered as an achievement for Bangladesh in the advanced Era. With the effective dispatch and situated in an orbit, this is a proper journey towards the space age for this developing nation that became freedom just 47 years ago. The main objective of this research is to study and compare to analyze the performance of different modulation techniques relevant to the Bangabandhu Satellite-1 communications system. The working principle and modulation techniques of Bangabandhu Satellite-1 as well as the advantages of this satellite in Bangladesh are illustrated here. The analysis and design of the elements of modern satellite communications systems are considered here. Firstly, we have introduced the concept of satellite communication along with its background and motivation. A discussion of the history of BS-1 and its coverage area, technical aspects, frequency bandwidth, services, advantages, and key features are included. Next, we have described different types of analog and digital modulation, highlighting the ones that are being used in BS-1. The performance of different modulation techniques is implemented and compared using MATLAB based simulation. Finally, we can come to the conclusion that modulation techniques used in BS-1 are well serving the purposes considering its performance and beneficial criteria as compared with others.

다수의 인공위성-지상국 간 통신 스케줄 최적화 모형

정유진,김흥섭 한국산업경영시스템학회 2018 한국산업경영시스템학회지 Vol.41 No.1

In the satellite operation phase, a ground station should continuously monitor the status of the satellite and sends out a tasking order, and a satellite should transmit data acquired in the space to the Earth. Therefore, the communication between the satellites and the ground stations is essential. However, a satellite and a ground station located in a specific region on Earth can be connected for a limited time because the satellite is continuously orbiting the Earth, and the communication between satellites and ground stations is only possible on a one-to-one basis. That is, one satellite can not communicate with plural ground stations, and one ground station can communicate with plural satellites concurrently. For such reasons, the efficiency of the communication schedule directly affects the utilization of the satellites. Thus, in this research, considering aforementioned unique situations of spacial communication, the mixed integer programming (MIP) model for the optimal communication planning between multiple satellites and multiple ground stations (MS-MG) is proposed. Furthermore, some numerical experiments are performed to verify and validate the mathematical model. The practical example for them is constructed based on the information of existing satellites and ground stations. The communicable time slots between them were obtained by STK (System Tool Kit), which is a well known professional software for space flight simulation. In the MIP model for the MS-MG problems, the objective function is also considered the minimization of communication cost, and ILOG CPLEX software searches the optimal schedule. Furthermore, it is confirmed that this study can be applied to the location selection of the ground stations.

차기군위성통신에서 지상망 ALL-IP 연동을 위한 네트워크운용구조 및 데이터링크 프로토콜 연구

이창영,강경란,심용희 한국군사과학기술학회 2018 한국군사과학기술학회지 Vol.21 No.6

The military satellite communication of ROK military, ANASIS is designed for analog data such as voice and streaming data. ANASIS cannot fully support All-IP communications due to its long propagation delay. The next generation satellite communication system is being designed to overcome the limitation. Next generation satellite communications system considers both high-speed and low-speed networks to support various operating environment. The low-speed satellite supports both broadband and narrow-band communication. This network works as the infrastructure for of wide-area internetworking over multiple AS’s in the terrestrial network. It requires minimum satellite frequency and minimum power and works without PEP and router. In this paper, we propose a network operation structure to enable the inter-operation between high and low-speed satellite networks. In addition, we propose a data link protocol for low speed satellite networks.

Characteristics of the Real-Time Operation For COMS Normal Operation

조영민,박철민,김방엽,이상철,Cho, Young-Min,Park, Cheol-Min,Kim, Bang-Yeop,Lee, Sang-Cherl Korea Society of Satellite Technology 2013 한국위성정보통신학회논문지 Vol.12 No.1

Communication Ocean Meteorological Satellite (COMS) has the hybrid mission of meteorological observation, ocean monitoring, and telecommunication service. The COMS is located at $128.2{\circ}$ east longitude on the geostationary orbit and currently under normal operation service since April 2011. In order to perform the three missions, the COMS has 3 separate payloads, the meteorological imager (MI), the Geostationary Ocean Color Imager (GOCI), and the Ka-band communication payload. The satellite controls for the three mission operations and the satellite maintenance are done by the real-time operation which is the activity to communicate directly with the satellite through command and telemetry. In this paper the real-time operation for COMS is discussed in terms of the ground station configuration and the characteristics of daily, weekly, monthly, seasonal, and yearly operation activities. The successful real-time operation is also confirmed with the one year operation results for 2011 which includes both the latter part of the In-Orbit-Test (IOT) and the first year normal operation of the COMS. 통신, 해양, 기상의 세 분야 복합 임무를 수행하는 천리안위성(Communication Ocean Meteorological Satellite: COMS)은 정지궤도 동경 $128.2{\circ}$에서 2011년 4월부터 현재 정상 운영 임무를 수행하고 있다. 세 임무를 수행하기 위해 천리안위성에는 3가지 탑재체인 기상탑재체(Meteorological Imager: MI), 해양탑재체(Geostationary Ocean Color Imager: GOCI), 통신탑재체(Ka-band communication payload)가 실려 있다. 세 가지 임무 운영과 위성 유지 관리를 위해 위성 관제가 실시간 운영으로 수행된다. 위성 실시간 운영은 명령과 원격측정자료를 통해 위성과 직접 통신하는 업무이다. 본 논문에서는 천리안위성의 실시간 운영 특성으로 지상국 장비 구성과 일일, 주간, 월간, 계절별, 연간 운영 업무 특성을 논하였다. 천리안위성의 궤도상 시험(In-Orbit-Test: IOT) 말기와 정상 운영 첫 해가 포함되는 2011년의 1년간 운영 결과에 대한 토의를 통해 성공적인 실시간 운영 결과 확인도 제시하였다.

Performance Analysis of DPSK Optical Communication for LEO-to-Ground Relay Link Via a GEO Satellite

Lim, Hyung-Chul,Park, Jong Uk,Choi, Mansoo,Choi, Chul-Sung,Choi, Jae-Dong,Kim, Jongah The Korean Space Science Society 2020 Journal of Astronomy and Space Sciences Vol.37 No.1

Satellite optical communication has gained significant attention owing to its many quality features (e.g., a larger bandwidth, license free spectrum, higher data rate, and better security) compared to satellite microwave communication. Various experiments have been performed during many space missions to demonstrate and characterize inter-satellite links, downlinks, and uplinks. Korea has also planned to establish an experimental communication system using a geostationary earth orbit (GEO) satellite and the Geochang station as an optical ground station for low Earth orbit (LEO)-to-ground optical relay links. In this study, the performance of inter-satellite communication links and downlinks was investigated for the new Korean experimental communication system in terms of link margin, bit error rate (BER), and channel capacity. In particular, the performance of the inter-satellite links was analyzed based on the receiving apertures and the transmitting power, while that of the downlink was analyzed in terms of atmospheric turbulence conditions and transmitting power. Finally, we discussed two system parameters of receiving aperture and transmitting power to meet the three criteria of link margin, BER, and channel capacity.

인공위성 활용 분야 기술 발전 현황 및 전망

이정호(Jeong-Ho Lee),윤보열(Bo-Yeol Yoon),김윤수(Youn-Soo Kim),임덕원(Deok-Won Lim),허문범(Moon-Beom Heo),이병선(Byoung-Sun Lee),오현웅(Hyun-Ung Oh) 한국항공우주학회 2016 韓國航空宇宙學會誌 Vol.44 No.8

우리나라는 그동안 국가주도의 위성개발사업을 통해 다수의 위성을 개발하였으며, 현재 다양한 센서의 지구관측위성, 과학기술위성, 통신위성 등을 운영하고 있다. 위성은 많은 분야에서 활용될 수 있으며 대표적인 활용분야는 위성정보, 위성항법, 위성통신방송, 우주태양양광발전시스템 등이 있다. 우리나라가 다양한 위성을 보유한 현 상황에서 이제는 위성활용에 역량을 더 집중해야한다. 본 논문에서는 위성정보, 위성항법, 위성통신방송, 우주태양양광발전시스템에 대하여 기술발전 현황을 살펴보고 미래 전망을 분석하였다. Korea developed several satellites through government-led satellite development projects, and now operates earth observation satellites of various sensors, science and technology satellites, and communication satellites. Satellites can be utilized in many fields, and Satellite Information, Global Navigation Satellite System, Satellite Communications and Broadcasting, Space Solar Power System are typical application fields. Now that we have developed and operated several satellites, we have to concentrate more efforts on satellite application. In this paper, we reviewed the current states of the technologies of four satellite application fields mentioned above and analyzed the future prospects of them.