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7. Status Update on Laser Communication Activities in NICT

Author

Kolev, Dimitar, primary, Shiratama, Koichi, additional, Carrasco-Casado, Alberto, additional, Saito, Yoshihiko, additional, Munemasa, Yasushi, additional, Nakazono, Junichi, additional, Trinh, Phuc V., additional, Kotake, Hideaki, additional, Kunimori, Hiroo, additional, Kubooka, Toshihiro, additional, Fuse, Tetsuharu, additional, and Toyoshima, Morio, additional

Published
2022
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10. A study on Satellite-Terrestrial Cooperation System as a Part of Research and Development of Ka-band Satellite Communication Control for Various Use Cases

Author

Sekiguchi, Mariko, primary, Miura, Amane, additional, Abe, Yuma, additional, Otsuru, Go, additional, Morikawa, Eihisa, additional, Yoshimura, Naoko, additional, Takahashi, Takashi, additional, Kubo-Oka, Toshihiro, additional, Fuse, Tetsuharu, additional, Tsuji, Hiroyuki, additional, and Toyoshima, Morio, additional

Published
2021
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12. Development of Advanced HTS Onboard Ka-band Antennas for Engineering Test Satellite 9

Author

Kusano Masaaki, Tsuji Hiroyuki, Kanasashi Arimasa, Yoshimura Naoko, Okawa Mitsugu, Abe Yuma, Orikasa Teruaki, Tanaka Tai, Toyoshima Morio, Sunaga Terumi, Morikawa Eihisa, Tsunoda Toshiyasu, Miura Amane, Uchida Shigeru, Horie Nobuyoshi, Sakai Eiichi, Okura Takuya, and Takahashi Takashi

Subjects
business.industry, Computer science, Astrophysics::Instrumentation and Methods for Astrophysics, Electrical engineering, Spectral efficiency, Communications system, High-throughput satellite, Ka band, Satellite, Antenna (radio), business, Throughput (business), Beam (structure), Computer Science::Information Theory
Abstract

We have developed the advanced onboard antennas for High Throughput Satellite (HTS). They are three types of the antennas utilizing Ka-band frequencies to aim in-orbit verification by the Japanese Engineering Test Satellite 9 (ETS-9). First antenna is the fixed multi-beam antenna (Fixed MBA) employing the miniaturized and integrated feeder unit to enable dense allocation of multi beams for improvement of spectrum efficiency. Second antenna is the Digital Beam Forming antenna (DBF-ANT) to enable flexible beam shape. Third antenna is the common communications system antenna (CCS-ANT) transmitting broad beam which has beacon transmission function etc.

Published
2021
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16. Throughput Analysis for TCP Over the FSO-Based Satellite-Assisted Internet of Vehicles.

Author

Le, Hoang D., Trinh, Phuc V., Pham, Thanh V., Kolev, Dimitar R., Carrasco-Casado, Alberto, Kubo-Oka, Toshihiro, Toyoshima, Morio, and Pham, Anh T.

Subjects
TCP/IP, FREE-space optical technology, LOW earth orbit satellites, INTERNET, INTERNET access, COMBINED sewer overflows, DRONE aircraft
Abstract

Free-space optics (FSO)-based, low-earth orbit (LEO) satellite-assisted Internet of vehicles (IoVs) has recently attracted research efforts worldwide. For the majority of Internet applications, transmission control protocol (TCP) is one of the most widely deployed protocols. Nevertheless, a complete understanding of the TCP performance over FSO-based satellite-assisted IoVs networks is still lacking in the literature. This is a highly challenging issue, as a consequence of the non-trivial interdependencies between transmission losses caused by the dynamics/uncertainty of atmospheric last-mile channels and the buffer overflows on the Internet, as well as their joint impact on the TCP congestion control mechanisms. This paper offers a comprehensive analytical framework that allows assessing the TCP throughput performance under the joint impact of congestion losses occurred in the Internet and transmission errors at the last-mile link from the satellite-to-vehicle. Internet access for emerging unmanned aerial vehicles (UAVs) is considered while the analysis can be also applied to other kinds of vehicles, which, in fact, require simpler channel models. The link-layer incremental redundancy hybrid automatic repeat request (IR-HARQ) protocol is employed at satellite-to-UAV channels to further improve the TCP throughput performance. Numerical results provide non-trivial findings and insights for the TCP performance in satellite/FSO-based IoVs, in which optimal UAV’s parameters are chosen to maximize the TCP throughput. [ABSTRACT FROM AUTHOR]

Published
2022
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17. DBF-Based Fusion Control of Transmit Power and Beam Directivity for Flexible Resource Allocation in HTS Communication System Toward B5G.

Author

Takahashi, Masaki, Kawamoto, Yuichi, Kato, Nei, Miura, Amane, and Toyoshima, Morio

Abstract

The demand for satellite communication increases with digitalization and globalization in the era of 5G and beyond; therefore, research and development of high-throughput satellites (HTSs) to increase the communication capacity and improve the flexibility of satellite communication systems is underway. Additionally, digital beamforming (DBF), which can control the directivity of multiple beams through high-speed digital signal processing, has received significant attention as a technology to improve the flexibility of resource allocation with HTSs. The principal control parameters in the DBF-based HTS, including the transmission power, beam gain, and placement location of each beam, cause alterations in the positional characteristics of the total throughput in the coverage area of an HTS. However, there are no power resource allocation models with dual control of these control parameters, based on the above positional characteristic. This study clarifies the effect of such control parameters on the total throughput in the coverage area of an HTS. We demonstrate a method for improving the flexibility of resource allocation to satisfy the geographic distribution of traffic requirements by constructing a power resource allocation model with a DBF-based fusion control in the HTS communication system. We evaluated the effectiveness of our proposed method through a simulation analysis using exponential annealing. [ABSTRACT FROM AUTHOR]

Published
2022
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23. Recent Trends in Space Laser Communications for Small Satellites and Constellations.

Author

Toyoshima, Morio

Abstract

Free-space optical communications in space can realize broadband and large-capacity communications using smaller and lower-power-consumption onboard equipment. Recently, many mega-constellation systems have been planned and launched from various countries. Although the frequency spectra will soon be exhausted, optical communications have potentially wider bandwidths in the optical spectrum and are a viable alternative. Because optical communications do not have regulatory restrictions or licensing issues, this technology can revolutionize the space system architecture. This article describes the recent trends and future prospects of space laser communications. [ABSTRACT FROM AUTHOR]

Published
2021
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24. Flexible Resource Allocation With Inter-Beam Interference in Satellite Communication Systems With a Digital Channelizer.

Author

Kawamoto, Yuichi, Kamei, Taiki, Takahashi, Masaki, Kato, Nei, Miura, Amane, and Toyoshima, Morio

Abstract

Satellite communication systems have attracted considerable attention recently because they can communicate in various conditions, including terrestrial, airspace, and marine terrain. In addition, high-throughput satellites (HTSs) that allow high-speed and large-capacity communication are currently being launched. However, the allocation of communication resources to each beam is fixed in conventional HTSs, which exhibit low flexibility under state changes. This includes requests to the satellite communication systems or environmental changes around the systems. Therefore, the use of a digital channelizer in a satellite communication system can allocate frequency resources to each beam. However, even if a digital channelizer is used, conventional frequency resource allocation methods that consider inter-beam interference do not use the same frequency resource as the adjacent beam. As a result, the frequency resources cannot be used effectively. To alleviate this issue, we propose a frequency resource allocation method with inter-beam interference so that the satellite communication system can allocate frequency resources more flexibly. In addition, we extend the conventional flexibility analysis model such that it quantifies the flexibility more accurately. Finally, the effectiveness of the proposed method is demonstrated under state changes of the satellite communication system using the extended flexibility analysis model. [ABSTRACT FROM AUTHOR]

Published
2020
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26. Satellite Laser Communication Activities in NICT

Author

Kolev, Dimitar R., primary, Carrasco-Casado, Alberto, additional, Takenaka, Hideki, additional, Munemasa, Yasushi, additional, Trinh, Phuc V., additional, Saito, Yoshihiko, additional, Kunimori, Hiroo, additional, Koyama, Yoshisada, additional, Suzuki, Kenji, additional, Kubooka, Toshihiro, additional, and Toyoshima, Morio, additional

Published
2018
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35. Optical communication on CubeSats — Enabling the next era in space science

Author

Carrasco-Casado, Alberto, Biswas, Abhijit, Fields, Renny, Grefenstette, Brian, Harrison, Fiona, Sburlan, Suzana, Toyoshima, Morio, Carrasco-Casado, Alberto, Biswas, Abhijit, Fields, Renny, Grefenstette, Brian, Harrison, Fiona, Sburlan, Suzana, and Toyoshima, Morio

Abstract

CubeSats are excellent platforms to rapidly perform simple space experiments. Several hundreds of CubeSats have already been successfully launched in the past few years and the number of announced launches grows every year. These platforms provide an easy access to space for universities and organizations which otherwise could not afford it. However, these spacecraft still rely on RF communications, where the spectrum is already crowded and cannot support the growing demand for data transmission to the ground. Lasercom holds the promise to be the solution to this problem, with a potential improvement of several orders of magnitude in the transmission capacity, while keeping a low size, weight and power. Between 2016 and 2017, The Keck Institute for Space Studies (KISS), a joint institute of the California Institute of Technology and the Jet Propulsion Laboratory, brought together a group of space scientists and lasercom engineers to address the current challenges that this technology faces, in order to enable it to compete with RF and eventually replace it when high-data rate is needed. After two one-week workshops, the working group started developing a report addressing three study cases: low Earth orbit, crosslinks and deep space. This paper presents the main points and conclusions of these KISS workshops.

Published
2017

36. Construction of a Flexibility Analysis Model for Flexible High-Throughput Satellite Communication Systems With a Digital Channelizer.

Author

Kaneko, Kazuma, Nishiyama, Hiroki, Kato, Nei, Miura, Amane, and Toyoshima, Morio

Subjects
TELECOMMUNICATION satellites, SPECIALTY channels (Television programs), SPECTRUM allocation, CHANNEL spacing (Telecommunication), TELEVISION frequency allocation
Abstract

Recent years have seen the development of a satellite communication system called a high-throughput satellite (HTS), which enables large-capacity communication to cope with various communication demands. Current HTSs have a fixed allocation of communication resources and cannot flexibly change this allocation during operation. Thus, effectively allocating communication resources for communication demands with a bias is not possible. Therefore, technology is being developed to add flexibility to satellite communication systems, but there is no system analysis model available to quantitatively evaluate the flexibility performance. In this study, we constructed a system analysis model to quantitatively evaluate the flexibility of a satellite communication system and used it to analyze a satellite communication system equipped with a digital channelizer. [ABSTRACT FROM AUTHOR]

Published
2018
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39. First results of wavefront sensing on SOTA

Author

Vedrenne, Nicolas, primary, Velluet, Marie-Therese, additional, Petit, Cyril, additional, Michau, Vincent, additional, Chabe, J., additional, Ziad, A., additional, Phung, Duy-Ha, additional, Maurice, Nicolas, additional, Samain, Etienne, additional, Artaud, Geraldine, additional, Issler, Jean-Luc, additional, Toyoshima, Morio, additional, Akioka, Maki, additional, Kolev, Dimitar, additional, Munemasa, Yasushi, additional, Takenaka, Hideki, additional, and Iwakiri, Naohiko, additional

Published
2015
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45. Satellite-to-ground optical communication system on Low Earth Orbit micro-satellite RISESAT

Author

Kuwahara, Toshinori, primary, Yoshida, Kazuya, additional, Sakamoto, Yuji, additional, Tomioka, Yoshihiro, additional, Fukuda, Kazufumi, additional, Fukuyama, Masato, additional, Sugimura, Nobuo, additional, Kunimori, Hiroo, additional, Takenaka, Hideki, additional, Toyoshima, Morio, additional, Fuse, Tetsuharu, additional, and Kubooka, Toshihiro, additional

Published
2012
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