Advances in Communications Satellite Systems: Proceedings of the 37th International Communications Satellite Systems Conference (ICSSC-2019)
2: Innovative Aerospace Information Systems, USA
3: Department of Electronics and Bioinformatics, Meiji University, Kawasaki, Japan
The International Communications Satellite Systems Conference (ICSSC) is the oldest and one of the most influential technical conferences in the field. The 37th edition was held from 29 Oct - 1 Nov 2019 in Okinawa, Japan. These proceedings present a broad spectrum of space communications contributions from the conference, with highlights including high speed optical communications and feeder links, advanced digital payloads, broadband satellite communication architectures and applications. Subjects covered include integrated applications and architectures for vessels and IoT; DTN and HTS technologies; new satellite system architectures and components; high speed optical communications and feeder links; advanced digital payloads and components; satellite antenna technologies; propagation and modelling for satellite communications; future technologies for 5G and beyond; flexible HTS systems and advanced digital payloads; satellite networks design challenges and applications; new satellite components and transmitter and modem technologies; NGSO constellations and 5G integration; and NGSO and GSO system issues and interference mitigation techniques. Offering a wide range of expert perspectives on communications satellite systems, these proceedings will be of interest to engineers and researchers in academia and industry working on satellite, digital, and wireless communications and networks, as well as advanced students, policy makers and stakeholders in the field.
Inspec keywords: optical communication; Long Term Evolution; tracking; reflector antenna feeds; Internet of Things; quality of service; meteorology; telecommunication network reliability; laser beam applications; delay tolerant networks; III-V semiconductors; cognitive radio; OFDM modulation; telecommunication terminals; energy conservation; wide band gap semiconductors; electromagnetic wave propagation; MIMO communication; distortion; precoding; adaptive codes; adaptive modulation; Earth orbit; private key cryptography; electromagnetic coupling; interference suppression; telecommunication power management; synchronisation; switching networks; transportation; radionavigation; satellite communication; test equipment; antenna radiation patterns; signal detection; emergency management; marine communication; 5G mobile communication; transponders; vegetation mapping; phase noise; UHF devices; marine robots; telecommunication links; adaptive optics; data communication; software radio; clouds; interference; frequency control; radiofrequency identification; radio spectrum management; modems; power control; radio transceivers; gallium compounds; artificial satellites; earthquakes; telecommunication channels; frequency division multiple access; oscillators; atmospheric turbulence; optimisation; MMIC; telecommunication security; measurement errors; array signal processing; millimetre wave power amplifiers; reflectarray antennas; calibration; decoding; broadband networks
Other keywords: integrated space-enabled hybrid 5G-V2X communications; laser communication infrastructure; International Communications Satellite Systems Conference; propagation direction estimation; interference mitigation techniques; return link; laser beam transmission; NICT; DBF antenna; ground station performance; ASCENT project; PAPR reduction; satellite communications propagation; engineering test satellite-9; turbulence impact; ACM; mega-constellations; satellite communications modeling; microsatellite body-pointing; timing drift estimation; high-speed tracking system; disaster countermeasure experiments; WINDS experiments; optical ground station; commercial communications satellites; broadband land mobile satellite communication systems; Ka-band satellite communications system; link characterization; advanced digital payloads; software-defined radio implementation; multibeam satellite communication systems; end-to-end data flows; self-calibration method; high-speed laser communication; external interference; RISESAT; measurement point reduction; autonomous shipping; site diversity; Ka-band mobile satellite communication; Ka-band on-the-move terminals; IoT; link budget design; hybrid analog-digital precoding design; integrated 5G-LEO communication; data transmission; digital predistortion; antenna pattern evaluation; time 40 year; VSOTA; graveyard orbits; carrier phase recovery; DVB-RCS2 satellite system; gallium nitride; mega-constellation design; DTN technologies; high-speed feeder links; small satellites; satellite integrated communication system; GNSS-assisted acquisition technique; 5G services; secret key agreement; reliable RF transceiver; optical observations; spectrum sharing schemes; cognitive communications; OFDMA; engineering test satellite 9; satellite-ground optical communications; UHF RFID tags; NASA Artemis 1 mission; marine robots operations; power control scheme; beam pattern optimization; beam-hopping system configuration; very high throughput satellites; 5G integration; ICSSC-2019; antenna propagation models; flexible HTS systems; MMIC power amplifier; seasonal vegetation changes; cloud blockage mitigation; frequency utilization efficiency; low earth orbit; long term ground meteorological observation data; downlink information; JAXA Uchinoura station; adaptive coding and modulation; decoding strategies; enterprise Ethereum blockchain; satellite MIMO system; integrated satellite-terrestrial network; optical intersatellite links; channel state modeling; LEO-based AIS; spectrum prediction; precoding performance; secure spacecraft tasking; channel capacity analysis; multibeam multicast satellite precoding systems; frequency flexibility; satellite transmitter; Ka-band transceiver sensitivity modeling; optimization tool; HICALI mission; performance evaluation; mutual coupling; optical communication experiment; RF optical transformation function; WINDS satellite; nonoperational satellites; secure spacecraft control; Japan; orbital altitude; Ka-band HTS applications; automatic identification system; interference detection; realistic payload characteristics; NGSO system; calibration method; high-throughput satellites; NGSO satellite network; satellite uplink asynchronous random access channels; maritime broadband communications; user terminal wideband modem; Kumamoto earthquakes; network switching controls; land broadband communications; differential oscillator phase noise; trunking systems; GaN; Satcom R&D; licensed shared access testbed; satellite laser communications; Australia; satellite antenna technologies; integrated satellite-terrestrial communications; bit rate 3.2 Gbit/s; LEO-to-ground links; HTS technologies; gating process; VL SNR channel; K-band transceiver sensitivity modeling; channel phase effects; DVB-S2x standard; NR-based NTN system; information rate; broadband satellite communication architectures; uplink information; optical ground systems; energy-efficient user terminals; digital satellite payloads; array antenna; systematic errors; communications link modeling; 5G Internet of things application; ETS-IX; mobile satellite communications; satellite experiments; GEO-to-ground links; NASA space systems; high-speed pixelated acquisition; hardware precoding demonstration; satellite base stations; high-rate delay-tolerant networking; high-performance V-band GaN MMIC HPA; Ka-band digital beam forming antenna payload; GEO system; direct spectrum division transmission; array-fed reflector configuration; multibeam UHTS communications; satellite communications systems; terminal synchronization; DVB-S2X; satellite networks design; reconfigurable antennas; digital beam forming receiving calibration; timing drift compensation; QVlift project; NGSO constellations; multiple transponders; 5G waveforms; quality of service; cloud climatological study; high-speed optical communications; space optical direct communications; fixed satellite services; fan-fold Ka-band large reflector; LTE over satellite; adaptive optics
Subjects: Radio links and equipment; Measurement standards and calibration; Optical communication; Optimisation techniques; Electromagnetic compatibility and interference; Computer communications; Frequency control; Instrumentation and techniques for geophysical, hydrospheric and lower atmosphere research; Oscillators; Energy utilisation; Instrumentation and measurement systems; Metrology; Emergency management; Digital signal processing; Other topics in Earth sciences; Laser applications; Conference proceedings; Data security; Optimisation techniques; Mobile, ubiquitous and pervasive computing; Mobile robots; Antennas; Lower atmosphere; General and management topics; Modulation and coding methods; Solid Earth physics; Stations and subscriber equipment; Control applications in telecommunications; Power and energy control; Optical materials and devices; Aerospace; Optics; General electrical engineering topics; Convection, diffusion, mixing, and turbulence in the upper atmosphere; Computer networks and techniques; Microwave integrated circuits; Amplifiers; Antenna theory; Testing equipment; Transportation system control; Radionavigation and direction finding; Communication system theory; Signal detection
- Book DOI: 10.1049/PBTE095E
- Chapter DOI: 10.1049/PBTE095E
- ISBN: 9781839531453
- e-ISBN: 9781839531460
- Page count: 930
- Format: PDF
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Front Matter
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Communications satellite systems: retrospect and prospect
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The International Communications Satellite Systems Conference (ICSSC) is widely regarded as the world's leading technical conference in the field of communication satellite systems. It is certainly the oldest conference in the field, the maiden edition of ICSSC having taken place in 1966 to commemorate the first anniversary of the launch of the world's first commercial communications satellite, Early Bird (later renamed Intelsat I) on April 06, 1965. Held biennially in even numbered years from 1966 through 2000 and annually since 2001, the 2019 event in Okinawa Japan was therefore the 37th edition of the conference. It brought together researchers, practitioners and experts in academia, industry, space agencies, and regulatory organizations around the world to formulate and exchange the latest ideas and to strengthen alliances and establish new partnerships and collaborations.
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Section 1: Broadband satellite communication architectures and applications
1 The results of WINDS experiments of NICT
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The Wideband InterNetworking engineering test and Demonstration Satellite (WINDS) was developed for the research of high-data-rate satellite communication technologies using Ka-band. WINDS was launched on February 23, 2008 and completed its operation on February 27, 2019. The National Institute of Information and Communications Technology (NICT) planned and conducted various experiments, such as satellite communication experiments for disaster countermeasures, an orthogonal frequency-division multiplexing transmission experiment, and mobile satellite communication experiments, using a small vehicle earth station, an airborne earth station, and a seaborne earth station.
2 Report of 3.2 Gbps transmission experiment result using WINDS satellite
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The National Institute of Information and Communications Technology (NICT) has experimented using a 1,244 Mbps high-speed burst modem with single carrier QPSK modulation through a bandwidth of 1.1 GHz transponder on the Wideband InterNetworking engineering test and Demonstration Satellite (WINDS). We developed a 16APSK/16QAM-OFDM 3.2 Gbps radio frequency signal direct-processing transmitter and receiver system for even greater broadband transmission. This chapter shows that a 4K UHDTV transmission demonstration experiment using WINDS satellite bent-pipe transponder through a 10 GbE interface was successfully performed by this system.
3 Disaster countermeasure experiments using WINDS and the response of 2016 Kumamoto earthquakes
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Based on the lessons learned from the Great East Japan Earthquake, the National Institute of Information and Communications Technology has developed a mobile vehicle earth station for Wideband InterNetworking engineering test and Demonstration Satellite (WINDS) by which the emergency response organization itself can collect and transmit the latest damage situation in real-time while moving. Furthermore, National Institute of Information and Communications Technology (NICT) has carried out disaster countermeasure experiments, such as providing added functions, necessary for disaster countermeasures for the mobile vehicle station while acquiring emergency response agencies' cooperation, such as municipalities and fire departments. When the Kumamoto earthquakes occurred in 2016, NICT dispatched the mobile vehicle station to Takamori Town, Kumamoto Prefecture, built an emergency network, and provided an Internet satellite line using WINDS through the Kashima Space Technology Center. This chapter will introduce the mobile vehicle earth station for WINDS, which we have developed aiming for disaster countermeasures after the Great East Japan Earthquake, the content of disaster countermeasure experiments, and the emergency network building and operation for the Kumamoto earthquakes in 2016.
4 Satellite integrated communication system for marine robots operations
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The ocean industry in Japan has been in recession since the late 1990s. The Japanese government continues to capitalize on new ocean businesses such as the development of underwater minerals, ocean wind farms, and so on. But most of these items are not yet commercialized. Japan should vitalize the ocean industries since we have a huge area of the territorial sea and exclusive economic zone (EEZ) (the sixth biggest country in the world). To vitalize them significant cost reduction of works in/on the sea will be necessary. It will be achieved by automation or unmanned work in a harsh environment. The utilization of autonomous marine robots is an effective unmanned way to achieve this cost reduction. It would be better that the robots autonomously deal with dynamic change of environment and are remotely controlled by operators for mission execution. In this scheme, a real-time broadband satellite link is very important. Japan Agency for Marine-Earth Science and Technology has continuously conducted experimental research on how to apply satellite systems to a robot. The requirements for communication satellite to vitalize Japan's ocean industry include covering Japan's EEZ, minimum data rate of 5 Mbps, maximum latency of 300 ms, small earth station (easy to install on robots), completely unmanned operation of earth station, low consumption power, automatic restoration and connection, and low cost.
5 Evolution of Ka-band on-the-move terminals for land and maritime broadband communications
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The development of three SATCOM on-the-move (SOTM) terminals designed to operate on the Wideband InterNetworking engineering test and Demonstration Satellite is discussed. All three terminals were able to achieve a tracking error of less than 0.2° and uplink data rate of at least 9 Mbps when operated under worst-case motion. Key design choices and improvements between the earliest and later designs are presented.
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Section 2: Integrated applications and architectures for vessels and IoT
6 Mega-constellations as enabler of autonomous shipping
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Autonomous and remotely controlled ships operating in the Arctic area will need the connectivity that cannot be provided with the current systems. This study concentrates on investigating what kind of satellite communication system is needed for reliable operations in the defined area when the main application is a drone-assisted situational awareness system for the autonomous ships. The conducted work defines communication architecture and the constellation needed for reliable communications. The results show that the defined mega-constellation system is able to meet the throughput and coverage requirements.
7 On decoding strategies for satellite uplink asynchronous random access channels
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In this chapter, we first review the state-of-the-art schemes for nonorthogonal multiple access where multiple users share the satellite channel radio resources. Among different grant-based and grant-free access schemes, we focus on nonslotted techniques, we study some decoding strategies to improve the performance of asynchronous contention resolution diversity ALOHA. Our preliminary results show that the performance of the decoder can be improved significantly if the information on overlapping bursts' powers and the exact differential delay among the incoming bursts are known at the receiver. We present the simulation results for a simple model and discuss the possible generalizations to a more realistic system scenario. Finally, we shortly discuss the efficiency of the physical layer abstraction methods under our model assumptions.
8 Software-defined radio implementation of UHF RFID tags in 5G Internet of things application
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The current and projected rapid increase in usage of the radio frequency identification (RFID) tags will yield new uses and applications in an Internet of things (IoT) environment. This chapter will discuss the implementation of software-defined radio (SDR) to aggregate, analytically process, and efficiently transmit data from RFID tags through a satellite backhaul solution. In the infrastructure proposed below, the first layer SDR aggregates RFID data at a tower level, the second layer SDR aggregates tower data at a low Earth orbit (LEO) satellite level, and then this aggregated data are backhauled to the gateway for the third layer SDR processing and data analytics. This chapter will discuss the RFID/SDR current and future capabilities, SDR design trades, RFID/ SDR system prototype test results, and satellite implementation scenarios.
9 Energy-efficient user terminals for Internet of things applications over satellite
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Motivation for this work is the development of a new satellite air interface for a low data rate massive access network in the context of machine-to-machine communications (M2M)/Internet of things (IoT) applications. For this purpose, this chapter considers energy efficiency at the user terminal and gives an evaluation of hardware-related aspects for an energy-efficient air interface and introduces a hardware concept involving energy harvesting in combination with an intelligent energy and system management. Typically, the performance of air interfaces is measured in terms of throughput, transmit error performances, etc. However, we evaluate for energy efficiency, an additional hardware-related aspect, which indicates the joint energy efficiency of hardware and transmission scheme. In particular, conventional continuous transmission of a message is opposed to discontinuous transmission by telegram splitting, as specified for the telegram splitting ultra-narrowband (TS-UNB) technology standardized by European Telecommunications Standards Institute (ETSI). Evaluations show that discontinuous transmission exploits the hardware components in a more efficient way than continuous transmission. This results in an extended use of the battery, which translates into a longer lifetime of the user node.
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Section 3: DTN and HTS technologies
10 Rising above the cloud: toward high-rate delay-tolerant networking in low earth orbit
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The high data rate architecture (HiDRA) project is implementing a high-rate delay-tolerant networking (HDTN) capability that can support low Earth orbit (LEO) applications and environments. The present state of the effort, future work, and other elements of the work to date are described in this chapter. This implementation is intended to support applications that run at 1+ Gbps per the requirements of modern optical and high-frequency radio frequency links. Uniquely, this implementation is also tuned to support relay and data trunking applications, which might require support for large numbers of small bundles per second. The design for this platform is based entirely on commercial-off-the-shelf (COTS) components and possesses buffering capabilities in the 5 TB range. This document takes results from previous individual tests and integrates them to demonstrate results in the presence of a coherent use-case, for example, consider a network aboard the International Space Station which intends to utilize an upcoming optical communications capability. For this use-case, orbital analysis software is used to analyze orbital dynamics, from which a list of access times are generated that might take in to account weather, schedule competition, etc. A variant of contact graph routing (CGR) is applied to these windows to determine an optimal schedule. This schedule is then loaded into the HDTN prototype and, in conjunction with various measurement tools, a complete end-to-end analysis of HDTN's performance is conducted. Various bottlenecks (including storage) are identified: these bottlenecks are expected to help us focus our future work on the elements of the system that are most likely to present issues moving forward. Finally, we discuss possible paths for evolution beyond the present rates supported by the system, including (but not limited to) hardware acceleration.
11 Integration of high-performance V-band GAN MMIC HPA for the QVlift project
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In the framework of the Horizon 2020 project QVLIFT, funded by the European Commission, a V-band high power amplifier based on gallium nitride (GaN) monolithic microwave integrated circuits (MMIC) technology was designed and developed. Design manufacturing and on-wafer pulsed measurements of two runs of MMIC fabrication were performed and the best chipsets demonstrated peak output power of about 5 W in pulsed mode. Waveguide modules were integrated and tested and are able to provide up to 2 W at 48 GHz in continuous wave.
12 Performance study of frequency flexibility in high throughput satellites and its contribution to operations strategy
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In this chapter, we describe a plan for comprehensive evaluation of a satellite communications (SATCOM) system with frequency flexibility. To cope with the more and more increasing demand of the SATCOM system, next-generation high-throughput satellites (HTS) will install a frequency flexibility function that can change the frequency assignment flexibly. To control this HTS, the flexible channel assignment method has been proposed. Under the time-varying traffic, this method performs higher throughput and reduces the number of control actions that change the frequency assignment. In the next step, comprehensive evaluation of the HTS system with the frequency flexibility is required. We summarize our previous results and describe a plan for the comprehensive evaluation of the HTS system in terms of performance index, communication traffic, and link assignment schemes. Finally, we suggest operations strategy of the HTS system including the predictive control.
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Section 4: New satellite system architectures and components
13 Satellite experiments on direct spectrum division transmission over multiple transponders
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We have been studying a direct spectrum division transmission (DSDT) technique that can divide a single carrier signal into multiple subspectra and assign them to dispersed frequency resources of the satellite transponder to improve the spectrum efficiency of the whole system. In a past study, we carried out fundamental satellite experiments on DSDT over a single transponder. This time, we conduct satellite experiments on DSDT over multiple transponders by using the latest DVB-S2X format signal. We expect using DSDT over multiple transponders will provide a new type of satellite communication service by raking unused frequency resources dispersed through multiple transponders.
14 User terminal wideband modem for very high throughput satellites
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The continuous increase of the demand for high data rate satellite services has triggered the development of new high-end satellite modems, which are capable of supporting a bandwidth of up to 500 MHz. For commercial application, the downlink from low Earth orbit (LEO) sensors and observation satellites is of a special interest. Such satellites should be capable of recording gigabytes of data and transferring it to the ground stations within a few minutes since the satellite is only visible for a short time at such low altitudes. This implies a very fast and reliable information processing at the terminal. For this, it would be beneficial to utilize the entire 1500 MHz spectrum of the extended Ka-band. In this context, the design of the modem architecture is very challenging. This problem is addressed in this chapter for the first time. We develop a new terminal modem architecture, which is expected to support a data rate in the range between 25 Msps and 1400 Msps. Through this, the receiver can easily adapt to changes in the data rate according to the traffic requirements. Furthermore, a simulator tool is developed, which is used for a numerical performance evaluation of the individual components and the whole system.
15 Licensed shared access testbed for integrated satellite-terrestrial communications: the ASCENT project
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The ASCENT project studies spectrum sharing between satellite and cellular networks using a licensed shared access (LSA) approach, in which information stored in a database is exploited to enable spectrum sharing between users. The project focuses on one side 5G pioneer bands 3.4-3.8 GHz and 24.25-27.5 GHz, which are well-recognized as satellite frequency bands, and on the other side on legacy international mobile telecommunication (IMT) frequency bands. We identified different spectrum sharing scenarios and defined four use cases. We have developed an LSA system testbed, which is used to study and validate the interest of the LSA approach in satellite/ terrestrial sharing scenarios. The results of our simulations and the tests realized on the testbed show that the LSA approach could be used to improve spectrum sharing between satellite and terrestrial networks. This approach could be envisaged to facilitate spectrum sharing between terrestrial mobile network such as international mobile telecommunications and satellite networks operating in a same frequency band. Such an approach could offer new spectrum sharing opportunities which could benefit to both mobile and satellite community. The LSA testbed and the results of the project will be further utilized to develop and assess new sharing scenarios that could lead to creating new spectrum opportunities for different radiocommunication systems.
16 Cognitive communications for NASA space systems
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The growing complexity of spacecraft constellations, communication relay offerings, and mission architectures drives the need for the development of autonomous communication systems. The National Aeronautics and Space Administration (NASA) has traditionally launched single spacecraft missions that are served by the Space Communication and Navigation (SCaN) program. Operations on SCaN networks are typically scheduled weeks in advance, and often each asset serves a single user spacecraft at a time. Recent movement towards swarm missions could make the current approach unsustainable. Additionally, the integration of commercial communication service providers will substantially increase the data transfer options available to new missions. NASA science missions have found benefit in launching swarms of space-craft, allowing coordinated simultaneous observations from different perspectives. Inter-spacecraft communication (mesh networking) is an enabler for this architecture, as are CubeSats that allow cost-effective provisioning of distributed mission assets. As more complex swarm missions launch, one challenge is coordinating communication within the swarm and choosing the appropriate mechanism for telemetry, tracking, control, and data services to and from Earth. Cognitive communications research conducted by SCaN aims to mitigate the increasing communication complexity for mission users by increasing the autonomy of links, networks, and service scheduling. By considering automation techniques including recent advances in artificial intelligence and machine learning, cognitive algorithms and related approaches enable increased mission science return, improved resource utilization for service provider networks, and resiliency in unpredictable or unplanned environments. The Cognitive Communications Project at the NASA Glenn Research Center develops applications of data-driven, nondeterministic methods to improve the autonomy of space communication. The project emphasizes the development of decentralized space networks with artificial intelligence agents optimizing communication link throughput, data routing, and system-wide asset management. This chapter discusses the objectives, approaches, and opportunities of the research to address growing needs of the space communications community.
17 Supporting NASA Artemis 1 mission with JAXA Uchinoura station
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This chapter presents an ongoing effort in preparing JAXA Uchinoura station support to the Artemis 1 mission, scheduled for launch in late 2020. The system involves three key participants: JAXA ground station at Uchinoura, the Deep Space Network (DSN) components at the Jet Propulsion Laboratory, California, and the Artemis 1 mission navigation at the NASA Johnson Space Center, Texas. Demonstration of Uchinoura station support to the future Artemis signal relies on the use of a low-cost, highly-portable software-defined radio (SDR) test equipment as well as the tracking of the Lunar Reconnaissance Orbiter (LRO) spacecraft. Using the SDR equipment, we validated the compatibility of signal format between the Artemis flight radio and the Uchinoura ground station without having to send the flight equipment to the station. By tracking an ongoing operational spacecraft such as LRO, we were able to calibrate the performance of the system in real operational conditions. The measured Doppler noise of 0.03 Hz (1-sigma), or 0.002 m/s range rate at S-band, for Uchinoura station is deemed suitable to the Artemis 1 mission navigation needs. This chapter also discusses the test equipment capability and its performance. In addition to being low cost, the equipment offers many advantages compared to the traditional full-scaled test signal simulator. Chief among them is portability making system easy to set up and transport, and the fidelity of the test signal that it captures from spacecraft flight equipment. Some of the lessons learned, such as internal frequency stability of the test signal, are also reflected.
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Section 5: High-speed optical communications and feeder links 1
18 Implementation of the method for estimating propagation direction of laser beam transmitted from ground to satellite
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An implementation of the method to estimate the direction of the laser beam emitted from ground to satellite is proposed. The implementation employs two boresight cameras to observe the backscattered light of the emitted beam. To carry out the proposed method, it is necessary to estimate the center line of the image of the scattered light from the laser beam taken by the boresight camera. A simple method to find the center line of the image of the backscattered light is also proposed. Since the accuracy of the estimation of the beam propagation direction should be known to design a free-space optical terminal, an experiment is performed to measure the angular error of the estimation by the proposed method.
19 Studies on site diversity to mitigate cloud blockage in satellite-ground optical communications based on long-term ground meteorological observation data
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Cloud blockage in Japan area is analyzed with the long-term ground-based observation data to find candidate sites for the site diversity scheme. First, the period in which both ground-based observation data and satellite-based observation data are available is confirmed. Next, from the viewpoint of the average cloud amount, and in consideration of the installation conditions of the optical ground station, some appropriate candidate sites are selected. Finally, the cloud amount correlation values among the selected sites are obtained, and the final candidate site combinations are listed.
20 Overview of optical ground systems developments for network switching controls to avoid cloud blockage in space optical direct communications
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For high-speed space communications, future needs of space optical communication technologies are further increasing to provide operation services of intersatellite links and direct links in the field of remote sensing and space explorations. However, cloud blockage of direct communication links is one of the issues in space optical direct communications, while the atmospheric effect on the communication links is also an important issue on the link quality in a given satellite path connected with optical ground stations. Space optical communication experiments have been performed and results have also been reported internationally, but many of them are mainly focused on communication link evaluations for stable optical direct links under atmosphere, while experiments of optical ground systems for avoidance of cloud blockage with ground network switching controls have not been sufficiently reported. For the network switching controls among optical ground stations based on cloud blockage on a given satellite path over stations, JAXA developed ground network systems. First, the laser ground network planning system is explained. Next, our optical ground stations and the infrared cloud monitoring and discrimination system for lower cloud blockage are explained. Finally, our planned network switching testings are explained.
21 Demonstration of high-speed pixelated acquisition and tracking system for optical intersatellite links
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Multiple emerging small satellite constellations aim to provide worldwide connectivity through high-speed free-space optical communication across many thousands of kilometers. The scale of these constellations requires a new approach to the design, build, and verification of high-performance space optics, one that will focus on mass-producibility, low-cost design, and limited touch-time. Honeywell and our partners have developed an optical intersatellite terminal that builds on our combined decades of experience in reliable space optics, electronics, and mass production of space hardware. The critical technical drivers of optical systems for space are their susceptibility to the thermal and radiation environments. The system is designed around Honeywell's Optical Pointing and Tracking Relay Assembly for Communications (OPTRAC), a low-cost subsystem which is designed to drive all of Honeywell's optical link products by providing a common interface between swappable front-end telescopes and back-end optical transceivers. The lowest-cost traditional approach to performing pointing and tracking is to apply quadrant photodiode sensors. These large-area devices have limited sensitivity and must maintain tight alignment tolerances over temperature. This chapter discusses the advantages and impacts of tracking with a pixelated sensor and presents results of laboratory testing and environmental qualification of a pixelated prototype subsystem.
22 An experimental study of RF optical transformation function
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Application of optical communication systems to satellite communications has started. On the other hand, radio frequency (RF) communication is used widely at present and stable service is offered. RF communication will coexist with optical communication in the future and hybrid systems will be enabled to exchange information widely and seamless networks will be built. Under this background, NEC has initiated a study of RF optical eXchange (RFOX) since January 2019, by using a ground evaluation model of RFOX (GRFOX). In this chapter, we will report on the study approach, schedule and progress to date.
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Section 6: Advanced digital payloads and components
23 Beam-hopping system configuration and terminal synchronization schemes
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In 2019, the digital video broadcasting (DVB) project published an updated specification of the DVB-S2X standard to improve the support of beam-hopping systems. This was on the one hand due to market needs for enhanced efficiency and flexibility compared to conventional systems but on the other hand also enabled by emerging satellite technologies such as active antenna and beam forming solutions that allow for practical implementation of the beam hopping systems. To this end, this chapter discusses system deployment and configuration scenarios as well as features of the DVB-S2X standard specification for beam-hopping. Furthermore, potential terminal features and synchronization schemes are described, which includes an essential algorithm for the start of illumination detection.
24 Adaptive coding and modulation (ACM) and power control scheme for return link of DVB-RCS2 satellite system
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In this chapter, we investigate a DVB-RCS2-based satellite communication system consisting of a gateway, a satellite, and a return channel satellite terminal (RCST). We formulate an optimization problem to maximize the transmission rate of the system. To solve the problem, we propose an adaptive coding and modulation (ACM) and power control scheme for return link transmission based on the return channel condition and power headroom of the RCST. Simulation results show that the proposed ACM and power control scheme increases the transmission rate as the transmit power of RCST and satellite increases or the power headroom of RCST increases.
25 A study of frequency utilization efficiency of OFDMA adaptive coding and modulation on Ka-band satellite communications system
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We investigate adaptive coding and modulation (ACM) with orthogonal frequency-division multiple access (OFDMA) relative to maintaining highfrequency utilization efficiency according to the change of power and frequency bandwidth limited channels on Ka-band high-throughput satellite (HTS) systems. Using the DVB-S2X modulation scheme for OFDMA, implementation of ACM results in improved frequency utilization efficiency.
26 Antenna pattern evaluation formed by reconfigurable antennas with the configuration of an array-fed reflector
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The R&D project aimed to realize the beamforming flexibility for Ka-band high throughput satellite is now in progress. The important technological challenge is to establish the wideband digital beamforming (DBF) technology. The developed technology is planned to be tested in orbit by the engineering test satellite-9. In this chapter, the beamforming capability of DBF with the configuration of an array-fed reflector is investigated. Antenna patterns are evaluated by considering the different restrictions on excitation coefficients between DBF and a conventional active phased array antenna (APAA). The excitation phase and amplitude of APAA is constrained to the assumed discretized values. The sidelobe levels formed by DBF achieve an excellent performance of more than 5 dB compared to APAA. We confirmed the more flexible beamforming capability of DBF.
27 Gallium nitride MMIC power amplifier for use in Ka-band HTS applications
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There is a need for solid-state power amplifiers (SSPAs) to be used in commercial satellite applications. Specifically with respect to high throughput satellites (HTS) where the amount of information passed through the transponders, that is, capacity, is determined mainly by the quantity of beams the satellite can generate. This application is well suited for SSPAs over the conventional TWTA solution as they are smaller and lighter weight enabling a simplification of HTS payload architectures, higher density physical integration, and the ability to support active array transmit solutions all of which increases the quantity of beams and thus capacity. However, this is also dependent on the SSPA's DC power and thermal dissipation as these are limited by a satellite's ability to generate the DC power and remove the thermal energy created by these types of units. Gallium nitride (GaN) power amplifiers (PAs) have shown the ability to generate high RF output power levels with small size and high efficiency thereby enabling step-function improvement in capacity for our emerging generation of HTS [1]. For this effort, K-band power amplifier breadboards were designed, fabricated, and tested. The purpose of the breadboards was to validate the baseline approach to meet the challenging performance required for HTS. These requirements were based on the need to increase satellite capacity. Maxar Space Infrastructure leads the industry in launched HTS capacity, with SSL having built some of the world's highest capacity spacecraft, with initial HTS systems of 50 GBps, innovating 100 GBps class, then to 200 GBps class, and now over 500 GBps class solutions [2]. This trend of nearly doubling the throughput capacity with each innovated new generation continues to project forward with the need for higher capacity solutions. This chapter will describe the design and performance of the GaN PA breadboards. Measurements of three key parameters-RF power out (Pout), power added efficiency (PAE), and carrier to third order intermodulation level (C/3IM) and/or noise power ratio (NPR)-will be presented to describe the performance of the PA. Additionally, a description of the GaN PA MMICs and the module integration approaches utilized will be given. To the author's best knowledge, the results presented are the best reported for a GaN PA module in this frequency band.
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Section 7: High-speed optical communications and feeder links 2
28 Technological trends and future prospects of satellite communications for mega-constellations with small satellites
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Global satellite communications services provided by nongeostationary satellite systems have been planned and launched from many countries. Small satellites are smaller, lighter, and cheaper than conventional satellites and will revolutionize space systems architecture. The advantages of low Earth orbit and medium Earth orbit satellite constellations are low latency and the lower power required due to the shorter distance; however, there is a problem with frequency allocation. This chapter describes the technological trends and the future prospects of satellite communications for megaconstellations with small satellites and the frequency allocation problem.
29 Commercial communications satellites in the post-2020 era
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The commercial segment of the satellite communications industry has led the way in terms of innovation and investment. Beginning with the launch of Intelsat 1, Early Bird, in 1965, the size and coverage of satellites in general and geostationary Earth orbit (GEO) systems in particular, have complemented and sometimes matched that of both fiber optic and wireless resources. The latest trend toward high-throughput satellites and non-GEO constellations assures that space is still vital to a variety of users who can depend on the robustness and bandwidth offered by satellite links. Perhaps we are at a point of inflection reminiscent of the 1980s when cables began to take over long-haul telecom demands, and again in the 1990s when satellite TV took front stage in terms of monetary gains and general knowledge of space broadcasting. The Internet exploded in the late 1990s to become a foundation for almost all forms of communication and even product marketing. Satellites responded with the very small aperture terminal that could deliver medium data rates, but cable modems and 3G wireless proved the master. Post-2000, satellite links came back by proving their effeteness in supporting remote locations to extend cellular systems, serve ships and aircraft, and aiding the success of our defense forces by reaching beyond line-of-sight. This brings us to the current day where our ability to use space is unparalleled, yet some doubt that satellites can be relevant and even retain an innovative posture as the world adopts 5G. To this, we can point to how the fundamentals cannot change as to the advantages of the space link and coverage of the planet, and of outer space for that matter. We discuss construction of space systems to apply low Earth orbit (LEO), medium Earth orbit (MEO), and GEO, with advanced features to reach all people and places, providing them with information and critical support no matter their access to terrestrial wireless or fiber. We describe the processes needed to allow the space segment and satellite terminal devices to adapt to the user's situation, dependent on network connectivity and handoff performance. Ground facilities to access networks and resources will likewise arise from cloud technologies and intelligence to build infrastructure that can overcome prior disadvantages in remoteness and susceptibility to outage and other threats. This is the promise of the renewed commercial satellite communications segment, precisely because this is where innovators reside and where investment will always find a home.
30 5G and beyond for new space: vision and research challenges
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This chapter creates a vision for 5G and beyond satellite connectivity and discusses use cases where development is needed. We define a layered architecture for future integrated terrestrial-nonterrestrial networks and discuss what are the key communications technologies needed to make the operation reliable and efficient. We outline research challenges including high-frequency bands, spectrum sharing and interference management, optical communications, and network management using software-defined networking principles. Autonomous transport and autonomous satellites are described both as key drivers behind the development as well as disruptive technologies to fulfill future needs.
31 Direction of Satcom R&D in Japan: WINDS, ETS-IX, and beyond
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Advance satellite communications technology has been achieved through Wideband InterNetworking engineering test Satellite (WINDS) and Engineering Test Satellite 9 (ETS-IX) projects in these two decades in Japan. WINDS achieved Gbps-class transmission capability, wide bandwidth active phased array antenna in Ka-band, and high speed onboard switching technologies. ETS-IX is currently being developed to demonstrate flexible resource management capability with wide bandwidth digital channelizer and digital beam former in Ka-band. In this chapter, very high capacity optical communications technology being developed for feeder link applications of a very high throughput satellite is reviewed. Satellite communications are thought to be beneficial for 5G coverage expansion to the ocean surface, air and space, and some trials to integrate to 5G. ETS-IX will be used as an experimental platform for such technical trials based on European Space Agency-National Institute of Information and Communications Technology (ESA-NICT) collaborations. Based on these achievements and experiences, and taking into account the recent trend of satellite communications technology for VHTS, LEO constellations, HAPS, and so on, we have studied next-generation satellite communications technology.
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Section 8: Satellite antenna technologies
32 Development of highly maintainable and reliable RF transceiver for satellite base stations
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Maintainability and reliability are required to sustainably operate a satellite communication system. This chapter presents highly maintainable and reliable radio frequency (RF) transceiver structures for satellite base stations. We have developed two types of RF transceivers: one with a C-band gallium nitride (GaN) solid-state power amplifier (SSPA) and one with an output control manager of two Ku-band traveling wave tube amplifiers (TWTAs). We show the structures and evaluate the performances of the RF transceivers.
33 Fan-fold Ka-band large reflector and its applications
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Large aperture reflectors can have high radio frequency (RF) gain due to its large aperture and can be used to make flexible and appropriate services with recent digital processing technologies. Despite the performance of large aperture reflectors, most commercial geostationary communications satellites use up to 2.5 m aperture reflectors for high speed and fixed beam communication services due to rocket fairing size restrictions. To improve this situation, the recent discussions held by the Ministry of Internal Affairs and Communications Japan have concluded that large aperture reflector antennas for Ka-band are one of the key technologies to realize for the next generation of geostationary communications satellites. To this end, JAXA, or Japan Aerospace Exploration Agency, started to investigate the realization of 5 m aperture large deployable reflector of Ku/Ka-band for geostationary communication satellites. The reflector is a fan-fold deployable reflector and composed of a fan-fold deployable structure, a thin-plate network, and a metal mesh. The fan-fold deployable structure is designed as a Japanese fan, or “sensu,” and can be stowed in the manner of a folded fan. A rhombus lattice thin-plate network forms the parabolic surface. This chapter discusses the design concept of a fan-fold reflector and its applications.
34 The reduction of measurement point for self-calibration method of systematic errors for DBF antenna using gating process
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The National Institute of Information and Communications Technology (NICT) is currently researching and developing an array-fed reflector antenna that flexibly changes the coverage area using a digital beam-former (DBF) and improves the frequency utilization efficiency using a digital channelizer (DC) for next-generation communication satellites in the Ka-band. The systematic error calibration of an array feed is very important because the influence of phase errors appears prominently in the characteristics of the antennas. We propose a self-calibration system for an array feed using a pickup antenna and gating process to realize a more accurate systematic error calibration for array-fed reflector antennas. The calibration values for the array feed are obtained from the coupling characteristics using a pickup antenna from which the noise is removed by a gating process. This chapter shows the proposed method, procedure, and calibration results of the radiation pattern in an anechoic chamber. In order to determine the measurement parameters of the proposed method by parametric study, only the characteristics of the array feed were measured and evaluated. The calibration values, with gating a width of 0.01 ms, were almost the same compared with reference values. The calibrated radiation pattern using the proposed method was compared with a simulated radiation pattern, and the deviation in the Hand V-planes within a ± 60 range was about ±1.0 and ±0.6 dB, respectively. This chapter shows that the proposed self-calibration using a pickup antenna and gating process is effective for a DBF array feed.
35 Calibration method for array antenna considering mutual coupling in mobile satellite communications
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In this chapter, we propose a calibration method for an array antenna, which includes electromagnetic coupling between antenna elements. Conventional methods such as the rotating element electric field vector (REV) method for elements of an array antenna do not take into account the electromagnetic coupling between elements. If the antenna calibration is not properly performed, the radiation pattern of the radio waves in the undesired directions will increase and interfere with the other satellites that are not intended. To overcome this drawback, a model of an array antenna including the mutual coupling between antenna elements has been constructed. Using this model, the estimation problem of the effect of the mutual coupling is formulated as a formulation problem. Finally, a calibration method based on the solution of the optimization problem is derived and shows the effectiveness of the method through some numerical examples.
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Section 9: Propagation and modeling for satellite communications
36 Analysis of the impact of turbulence on adaptive optics ground station performance
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To date, many of the laser satellite communications downlink demonstrations have occurred at optical ground station (OGS) sites located at astronomical observatories, which are typically chosen for their favorable atmospheric characteristics including low turbulence. In this study, we investigate the effects of atmospheric turbulence on laser satellite communications performance for a low altitude ground site, where the effects of the turbulence can be more significant. In particular, we consider a site near sea level in Adelaide, South Australia where we are developing an OGS with adaptive optics (AO). A combination of experimental site turbulence measurements and numerical propagation modeling is used to undertake the investigation.
37 A 40-year cloud climatological study for Australia implications for siting of laser communication infrastructure
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Cloud cover, cloud properties, and the change in cloud cover over time are important variables to quantify in planning for ground-space bidirectional high bandwidth optical communication systems. As operators of optical communication systems will endeavor to function when skies have optically thin cloud cover, a climatological study that includes cloud physics in the dataset (i.e., cloud emissivity and cloud optical depth) will provide beneficial guidance. As a first step in undertaking such an investigation, we have initiated a study of the Australian continent with the aim of identifying any significant decadal trends in cloud climatology over a 40-year period. The database, covering PATMOS-x AVHRR cloud data from 1979 to 2018, includes sampling of the climatology at four times during the diurnal cycle so that selection of operating conditions can be further analyzed. Examples of the spatial and temporal variability of satellite-derived cloud fractional amounts over Australia will be presented along with an approach to analyzing and interpreting this information in aid of the decision-making process to optimize clear-sky optical ground station positioning. When used in conjunction with the average monthly cloud amount, monthly specific decadal time-specific anomalies can highlight when and where minimum levels of cloud cover occur.
38 Experimental results of seasonal vegetation changes on data transmission for Ka-band mobile satellite communication
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The National Institute of Information and Communications Technology (NICT) of Japan has performed communications propagation measurements between the Wideband InterNetworking engineering test and Demonstration Satellite (WINDS, also known as “KIZUNA”) and a moving vehicle earth station. With a focus on the future occurrences of a Nankai Trough earthquake and an associated giant tsunami, regions with a higher disaster risk have been selected for extensive study. Shadowing has been shown to have a large impact on satellite communications due to the use of a directional Ka-band antenna with high rectilinearity. The influence of shadowing is dependent on the seasons, as the conditions of the leaves vary by season for different types of trees. Therefore, in a previous study, we measured the attenuation of a received signal from the satellite throughout the year with shadowing from several types of trees to examine seasonal differences. The results of our year-long investigation revealed seasonal fluctuations in the received power beneath deciduous trees but no such variations beneath evergreen trees. In this chapter, we present the results of the measured user datagram protocol (UDP) throughput for Ka-band satellite communication.
39 Experimental study of external interference for LEO-based automatic identification system (AIS)
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In 2014, the Japan Aerospace Exploration Agency (JAXA) launched a second space-based automatic identification system (AIS), SPace-based AIS Experiment 2nd (SPAISE2), mounted on DAICHI-2. Then in May 2015, SPAISE2 entered an extended operations phase and is now continuously observing the seas around Japan to evaluate external interference and signal collision. This study reports on the separation of AIS messages and the external interference of large spike noise. And this chapter cites the heatmap of external interference and AIS messages on a low Earth orbit.
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Section 10: Future technologies for 5G and beyond
40 Advanced demonstration plans of high-speed laser communication "HICALI" mission onboard the engineering test satellite 9
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The National Institute of Information and Communications Technology (NICT) in Japan has over 20 years of experience in R&D of space-ground laser communications with missions. We are currently developing a laser communication terminal named “HICALI” (HIgh-speed Communication with Advanced Laser Instrument), aiming to achieve 10 Gbps-class space communications with a 1.5 μm-band laser beam between optical ground stations (OGSs) and the next-generation high-throughput satellite called ETS-9 with a hybrid onboard communication system using radio and optical frequencies, which will be launched into the geostationary orbit in 2021. Moreover, we have studied laser communication terminals for terrestrial networks, as an alternative wireless system to radio frequency (RF) band. The development of a test and breadboard model for HICALI has been conducted for several years and we are now carrying out an engineering model as well as designing the OGSs segment. In this chapter, we describe the current development status and advanced demonstration plans of the “HICALI” mission with ETS-9.
41 Optical communication experiment with microsatellite body-pointing using VSOTA on RISESAT
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The optical communication device VSOTA (a very small optical transmitter) developed by National Institute of Information and Communications Technology (NICT) was installed on the Rapid International Scientific Experiment Satellite (RISESAT) and launched in 2019. We are starting an initial orbit check using VSOTA. In this chapter, initial checkout experiments are performed and confirmed that VSOTA functions are operating normally.
42 Research and development of an optical ground station supporting both GEO- and LEO-to-ground links
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The Japanese National Institute of Information and Communications Technology has started the development of a novel optical ground station that will be able to support satellite-to-ground links for both geostationary and low-Earth orbit satellites. The design includes some of the main concepts in current standardization efforts that are taking place in the Consultative Committee for Space Data Systems. Different design issues have been discussed together with mission specifics and design solutions.
43 Optical observations of nonoperational satellites in graveyard orbits
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National Institute of Information and Communications Technology (NICT) plans to launch Engineering Test Satellite-9 (ETS-9) in the geosynchronous Earth orbit (GEO) in 2021. When the operation of a GEO satellite is terminated, it must be removed from the GEO protected region and maneuvered to a graveyard orbit. For example, ETS-8, former generation of ETS-9, ended its operation as planned in 2017 and moved to a graveyard orbit. Wideband Inter Networking engineering test and Demonstration Satellite (WINDS) suddenly ended its operation due to a communication error in 2019 and it could not be maneuvered to a graveyard orbit. From the above, we should be aware of the rotation of the objects not only in graveyard orbits but also of objects in GEO to ensure the safety of the operation of ETS-9 and also telecom, earth observation, and navigation satellites. In this study, we carried out optical observations for some of nonoperational satellites including ETS-8 and WINDS using a CCD camera attached to a 1-m telescope. We will report how to select the nonoperational satellites, the results of the optical observations, and the light curves of the satellites using photometry. As a result, we estimate the rotational status of the nonoperational satellites from the light curves.
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Section 11: Flexible HTS systems and advanced digital payloads
44 Development of Ka-band digital beam forming antenna payload for the engineering test satellite-9
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The R&D project entitled “Research and Development of Ka-band Wideband Digital Beam Forming for Efficient Frequency Use” has been started since July 2017. The goal of this R&D is the realization of beam location/shape flexibility for Ka-band high throughput satellite (HTS) and the improvement of frequency use efficiency compared with conventional HTS. This DBF payload is developed and planned to be tested in orbit by the engineering test satellite-9 (launch planned in FY 2021). This chapter describes the overview of R&D program and the current outcome of system development.
45 The initial study of calibrating receiving digital beam forming in engineering test satellite-9
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In realizing geostationary high throughput satellite (HTS), building flexible beam adapting to change of communication traffic is needed. Digital beam forming (DBF) has advantages of flexibility of beam steering and high integration. The R&D project focused on developing receiving DBF with Ka-band is ongoing. In DBF system, it is important to calibrate the gain, phase, and delay for each antenna element. In this chapter, we propose a method of calibration using digital processing on the satellite and ground station. The crosscorrelation vector between elements calculated in digital processor on the satellite is useful for detecting error of the gain, phase, and delay for each antenna element. These errors will be corrected with setting the correction coefficient to the satellite, which is calculated at the ground station with a cross-correlation vector transmitted from the satellite.
46 Beam pattern optimization based on up/downlink information for multibeam satellite communication systems
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To reduce the cost of satellite communications, it is important to minimize the number of beams by arranging the beams so as to suit the traffic load. Although a nonuniform beam pattern optimization method controlled by digital beam forming (DBF) has been proposed, its metric reflects only a single link's information. This conventional method using a single link's information cannot optimize the other links, thus it has limited ability to reduce the number of beams. Therefore, we propose a beam pattern optimization method which matches the traffic load in both the up and downlinks to reduce the required number of beams. The effectiveness of the proposed method is verified by simulation.
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Section 12: Satellite networks design challenges and applications
47 Channel state modeling and performance evaluation of DVB-S2X based broadband land mobile satellite communication systems
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The increasing demand of highly efficient wireless communication systems that supports high data-rates has been manifest with the fifth-generation (5G) system of systems. Satellite communications systems are to play significant role in supporting this system in terms of significant capacity enhancement, in addition to its ability to serve area where the terrestrial infrastructure is unable to provide services. The DVB-S2 standards are the candidates that will support this quest. The extension of the second generation of the DVB-S2X has further justified this advantage by incorporating higher modulation and coding schemes (MODCODs) such as the 64-APSK, 128-APSK, and 256-APSK. However, with the increasing utilization of on-the-move applications and services, the classical limitations of the satellite links in a mobile environment pose a problem to the seamless realization of capacity. These problems include signal fading due to path blockage, multipath propagation, and shadowing. A realistic mobile satellite channel has been modeled in MATLAB® using realistic terrain data which is processed in Systems Tool Kits simulator (STK) in order to determine the satellite-receiver access time leading to the determination of the Markovian Transition Matrix used for channel state condition. The performance of a good selection of DVB-S2X MODCODs has been presented and the new mobile channel has been used to test the effect on mobility on system performance. The result indicated that the mobility of the earth station causes degradation to the link performance, with scenarios of higher values of Rician K-factor, denoting the dominance of line-of-sight (LOS) being the best. Therefore, the need for further highly efficient receiver processing and optimal thresholds switching techniques that can support mobile channels in terms of high data-rate and availability is more than a prerequisite for the satellite component of the 5G systems.
48 Impact of antenna and propagation models on coexistence of 5G and fixed satellite services
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The progress of 5G new radio (NR) standardization and anticipated deployment of 5G services in both C-band and Ka-band has motivated many coexistence studies for cochannel spectrum sharing with incumbent fixed satellite service (FSS) operators. The use of proposed 5G antenna and propagation models in different urban and rural deployment scenarios impacts the definition of coordination and exclusion zones used to foster coexistence. This chapter analyzes the effect of spatial antenna gain variation and different propagation models on the shape of the coordination zones around FSS Earth station (ES) receivers.
49 Integrated space-enabled hybrid 5G-V2X communications link modeling
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Vehicle-to-everything (V2X) communication is the next innovative technology to transform the automotive industry. It implements the power of Internet of things (IoTs) connectivity and processing to improve the efficiency, performance, and safety of future vehicles. V2X enables vehicles to have a high awareness of the surrounding environmental factors, infrastructures, and other vehicles through the advanced sensing and communication technologies in place. Current communication platforms in place are not able to fully support the transmission of high priority safety critical data required to provide these services. Individually, the two main V2X architectures (DSRC and C-V2X) have limitations which inhibit them from fully supporting the V2X platform. As such, this chapter proposes the integration of 5G technology, which supports all types of communication technologies through the integration of reconfigurable devices and offers higher data rates and bandwidths than any preceding platform. The architecture proposed in the chapter is composed of three layers: DSR V2X for direct short-range communication; cellular V2X layer which will combine 5G cellular platform to provide backup communication when DSR V2X layer fails and multimedia capabilities; and satellite (SAT)-V2X which provides extra backhaul connectivity when both DSR and cellular V2X is unavailable. The system design, modeling, and simulation results yield a more reliable and sustainable V2X capacity for critical real-time vehicular communication applications.
50 K/Ka-band transceiver sensitivity modeling and link characterization for integrated 5G-LEO communication applications
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This chapter presents a transceiver sensitivity modeling and link characterization over-the-air (OTA) for K/Ka-band frequency for next-generation 5G and low earth orbit (LEO) communication applications. The transceiver system is simulated using estimated link budget parameters. The simulated transceiver includes a DQPSK modulator, a power amplifier, a low noise amplifier, and mixers optimized to meet industry specifications. The transmitter front-end shows a 24.6 dBm output power with an input transmission power of 0 dBm. The receiver simulation shows a gain of 48 dBm and an intermediate frequency output power of 35.8 dBm. The simulated sensitivity of the receiver spans from -115 dBm to -110 dBm, indicating good coverage over the channel bandwidth.
51 Link budget design for integrated 5G-LEO communication applications
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Fifth-generation (5G) promises an all-round connectivity scenario through the Internet of things, between people, and their environments as well as delivery of new communication levels and efficiency. To guarantee this goal of an all-round connectivity, the integration of satellite systems is vital based on the wide coverage area provided by satellite infrastructures. Hence a detailed analysis and definition of parameters and architectures for the seamless deployment of satellite systems within the 5G network is presented and captured in the design of a link budget for integrated 5G-low earth orbiting communication applications.
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Section 13: New satellite components and transmitter and modem technologies
52 Secret key agreement for satellite laser communications
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Free-space optical (FSO) communications offer high-capacity wireless transmission due to their plentiful properties originated from higher carrier frequency. These properties also yield a greater security advantage: the high directionality of the laser beam and the line-of-sight configuration can reasonably restrict an attack model launched by an eavesdropper (Eve). Secret key agreement over FSO links (FSO-SKA) employs this security advantage for key establishment between two distant parties, which is secure against Eve even with unbounded computer resources. In this chapter, we numerically evaluate the performance of FSO-SKA for satellite laser communications under the given power constraint. We also compare the performance of FSOSKA and quantum key distribution (QKD). Our result shows that FSO-SKA can generate a key even for the distance between geostationary orbit satellite and ground station. We anticipate that FSO-SKA has a potential to extend the secure satellite networks to global scale, which is hard only with QKD.
53 Methods for securing spacecraft tasking and control via an enterprise Ethereum blockchain
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Integration of space-based communications infrastructure within 5G networks presents specific challenges for spacecraft, namely a necessary rationalization of currently patchy communications security and the assurance of identity when conducting high-level spacecraft tasking and control operations. This chapter presents approaches to addressing both issues via the deployment of an enterprise Ethereum blockchain modified with a consensus algorithm appropriate for access by spacecraft. We discuss the applicability of enterprise Ethereum blockchains to the problem of spacecraft communication security, analyze the properties of blockchain consensus algorithms suitable for use with spacecraft, and suggest information architectures to allow secure spacecraft integration into 5G networks.
54 PAPR reduction and digital predistortion for 5G waveforms in digital satellite payloads
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Satellite systems will play an important role in the coming fifth generation (5G) of mobile communications. For a smooth integration of satellite networks into the terrestrial ones, the standardization bodies are pushing for shared spectrum. Therefore, it is of interest to study satellite specific scenarios, the applicability of multicarrier waveforms that have already shown promise to meet the requirements of the future mobile networks. 5G candidate waveforms such as filtered orthogonal frequency division multiplexing (f-OFDM), filter bank multicarrier (FBMC), and universal filtered multicarrier (UFMC) offer sharper out-of-band characteristics, significantly increasing the spectral efficiency. However, like OFDM, these waveforms exhibit a high peak to average power ratio (PAPR). A high PAPR saturates the nonlinear high power amplifier (HPA) which leads to nonlinear distortions in the on-board HPA's output. Moreover, signal clipping is often proposed in the literature to reduce the PAPR. However, clipping itself introduces nonlinear distortions within the signal bandwidth. Digital predistortion (DPD) can be applied to the clipped signal to remove the added nonlinear distortions while keeping the overall PAPR low. This chapter provides the simulation results on the application of the aforementioned waveforms to a satellite communication chain and presents the gains achieved by implementing DPD and clipping together in terms of PAPR, power spectral densities (PSDs), and bit error rates (BERs).
55 Effects of differential oscillator phase noise in precoding performance
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Satellite precoding is a promising technique to meet the target data rates of the future high throughput satellite systems and the costs per bit as required by 5G applications and networks, but it requires strict synchronization among the transmitted waveforms, in addition to accurate channel state information. Most of the published work about this topic consider ideal oscillators, but in practice, the output of an oscillator is not a single spectral line at the nominal frequency. This chapter proposes a model for the oscillator phase noise and analyzes the resulting received signal to interference plus noise ratio (SNIR) in a satellite communication system using precoding. Simulations of a communication satellite system with a two-beam transponder and two receivers were performed to compute the effective SNIR. This work uses a simulator which also considers practical impairments such as time misalignment, errors in the channel state information, interference, thermal noise, and phase noise masks for satellite oscillators. The precoding methods used for the analysis are zero forcing (ZF) and minimum mean square error (MMSE). The obtained results prove that there is a degradation in the performance due to the use of independent oscillators but this effect is compensated by the precoding matrix.
56 GNSS-assisted acquisition technique for LTE over satellite
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In this chapter, we describe an acquisition method for LTE over satellite, based on the standard 3GPP LTE PRACH waveform and processing procedures. The method is applicable when the user terminals are equipped and can utilize a global navigation satellite system (GNSS, e.g., GPS) receiver. The method requires modification of LTE user equipment (UE) only in software at layer 2 and reuse the PRACH preamble processing (detection and estimation) at the base station (eNodeB).
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Section 14: NGSO constellations and 5G integration
57 Information rate and quality of service guarantees for end-to-end data flows in an NGSO satellite network
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Nongeosynchronous orbit (NGSO) satellite networks have the potential to provide very high throughput, low delay, broadband services on a global scale and complement or even compete with terrestrial fiber and wireless services. However, providing services with information rate and quality of service guarantees is very challenging in these systems primarily due to their inherent dynamic, time-variant connectivity between network nodes. This chapter describes a combination of algorithms and procedures that work collectively to ensure that assured end-to-end services can be provided in an NGSO satellite network.
58 A new optimization tool for mega-constellation design and its application to trunking systems
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Nongeostationary mega-constellations have the potential to offer low-latency services to under-served geographical areas and aeronautical/maritime sectors. This will be enabled through a constellation involving low Earth orbit (LEO) fleet of satellites, which can be massively produced and inexpensively launched. Most of the existing trunking satellite systems are optimized (in terms of resources, processing, and architectures) for the GEO consolidated architecture. This system design vastly differs from the envisaged LEO system due to the motion ofthe satellite and limited coverage. This chapter considers the development of a tool to optimize the resources, processing, and architectures for next-generation LEO systems to meet the increasing requirements from trunking markets. The developed optimization tool jointly optimizes the number of beams, beam width, power, and bandwidth allocation in order to match the provided data rate to the predicted traffic demand. Due to the generic nature of the proposed method, further system parameters, such as orbit parameters, number of satellites, or frequency reuse factor, can be easily added to the list of optimization parameters. The proposed solution is numerically evaluated for a trunking market of static end users. The proposed solution shows a very good traffic matching and outperforms a naive approach without optimization.
59 Estimation and compensation of timing drift for NR-based NTN system
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The integration of satellite and terrestrial 5G (NR) networks aims to provide global coverage, improve service reliability, and enable the network scalability. However, the inherent characteristics of satellite channels bring challenges on the air interface design of integrated terrestrial-satellite networks. For example, due to the high-speed motion of low Earth orbit (LEO) satellite, timing drift has a serious impact on orthogonal frequency division multiplexing (OFDM)-based 5G (NR) system. In this chapter, we study the timing drift issue in the integration of satellite communication and 5G (NR) system. Signal processing-based methods are proposed to eliminate the impact of timing drift and the efficiency of the proposed methods is validated by simulation results.
60 Spectrum sharing schemes in integrated satellite-terrestrial network
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Nowadays, the demand of spectrum is rapidly increasing since the quality of communication has significantly been focused on by users. Therefore, as a research point of next generation network (NGN), integrated satellite-terrestrial network has been considered by institutions and universities. The most significant advantage of an integrated satellite-terrestrial network is taking full advantage of existing inadequate spectrum resources. In such network, the terrestrial system uses the same portions of frequency bands as an associated operational satellite system. This chapter intends to model and analyze several frequency sharing schemes in integrated satellite-terrestrial network with the analysis of unavoidable interference caused by frequency sharing and finally find the preferred solution.
61 Hybrid analog–digital precoding design for satellite systems
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The work investigates the feasibility of massive multiple-input multiple-output (MIMO) in SatCom. Toward this, the necessary channel models, system parameters, and scenarios are identified and a basic simulator is developed. The work then considers an efficient implementation of the massive MIMO transmission through the use of hybrid analog/digital precoder. Efficient algorithmic solutions are proposed for the partially connected precoder architecture which enables efficiency in power/hardware complexity and its performance evaluated.
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Section 15: NGSO and GEO system issues and interference mitigation techniques
62 Carrier phase recovery for DVB-S2x standard in VL SNR channel
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In this paper, we come up with a robust carrier phase synchronization scheme in DVB-S2x Annex E SF mode format 2 for VL SNR channel. Unlike DVBS2 standard, DVB-S2x standard can support VL SNR condition by around -10 dB which is useful for low profile antenna and heavy rain channel condition. The proposed scheme is applicable to reduce the FER performance degradation which is caused by inaccurate estimation. By means of computer simulations, we can show that there were practically much closer approaches over the ideal AWGN channel for the proposed scheme in terms of FER performance.
63 Spectrum prediction and interference detection for satellite communications
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Spectrum monitoring and interference detection are crucial for the satellite service performance and the revenue of SatCom operators. Interference is one of the major causes of service degradation and deficient operational efficiency. Moreover, the satellite spectrum is becoming more crowded, as more satellites are being launched for different applications. This increases the risk of interference, which causes anomalies in the received signal, and mandates the adoption of techniques that can enable the automatic and realtime detection of such anomalies as a first step toward interference mitigation and suppression. In this chapter, we present a machine learning (ML)-based approach which is able to guarantee a real-time and automatic detection of both short-term and long-term interference in the spectrum of the received signal at the base station. The proposed approach can localize the interference both in time and in frequency and is universally applicable across a discrete set of different signal spectra. We present experimental results obtained by applying our method to real spectrum data from the Swedish Space Corporation. We also compare our ML-based approach to a model-based approach applied to the same spectrum data and used as a realistic baseline. Experimental results show that our method is a more reliable interference detector.
64 Channel capacity analysis of satellite MIMO system depending on the orbital altitude
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With the improved sensor capabilities of Earth observation satellites and the introduction of constellation service in low Earth orbit (LEO), the volume of data transmitted from a satellite to a ground station is increasing. Multipleinput and multiple-output (MIMO) is hopeful for increasing the channel capacity in the power-limited and the band-limited channel. The authors have investigated the MIMO channels in LEO satellites, specifically proposing a channel model and assuming line-of-sight (LOS) environments. In the previous study, the authors analyzed channel capacity by using a channel model that randomly defines the satellite position. However, channel capacity that considers the parameters of the antenna position due to the satellite attitude must be analyzed. The authors evaluated the channel capacity on the LEOMIMO channel model by using the transmitting antenna distance and satellite altitude as parameters. As a result, the authors found that the channel capacity of an LEO-MIMO satellite varies at different time interval, and this time interval depends on the antenna distance and the altitude.
65 Effects of channel phase in multibeam multicast satellite precoding systems
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This chapter revisits the impact of channel phase in multibeam multicast satellite precoding. First, we analyze the unicast case showing that the phase components relative to the different slant paths to each user do not affect the precoding performance. Then, we indicate that for the multicast transmission, the mentioned phase effect may have impact depending on the employed clustering technique. Finally, we propose an alternative clustering solution based on normalizing out the phase components relative to the different slant paths. According to our simulation results, this novel clustering technique provides robustness to these phase components and also behaves better than previously reported clustering schemes.
66 Hardware precoding demonstration in multibeam UHTS communications under realistic payload characteristics
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In this chapter, we present a new hardware test-bed to demonstrate closed-loop precoded communications for interference mitigation in multibeam ultrahigh throughput satellite systems under realistic payload and channel impairments. We build the test-bed to demonstrate a real-time channel aided precoded transmission under realistic conditions such as the power constraints and satellite-payload nonlinearities. We develop a scalable architecture of an SDR platform with the DVB-S2X piloting. The SDR platform consists of two parts: analog-to-digital (ADC) and digital-to-analog (DAC) converters preceded by radio frequency (RF) front end and field-programmable gate array (FPGA) backend. The former introduces realistic impairments in the transmission chain such as carrier frequency and phase misalignments, quantization noise of multichannel ADC and DAC, and nonlinearities of RF components. It allows evaluating the performance of the precoded transmission in a more realistic environment rather than using only numerical simulations. We benchmark the performance of the communication standard in realistic channel scenarios, evaluate received signal SNR, and measure the actual channel throughput using LDPC codes.
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Back Matter
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