Satellite Communications in the 5G Era
2: Interdisciplinary Centre for Security, University of Luxembourg, Luxembourg
3: European Space Agency ESA/ESTEC, Noordwijk, Netherlands
Satellite communications (SatCom) plays a vital role in ensuring seamless access to telecommunications services anytime, and is a viable option for delivering telecommunication services in a wide range of sectors such as aeronautical, military, maritime, rescue and disaster relief. It should be an important component of 5G-and-beyond wireless architectures as it can complement terrestrial telecommunication solutions in various scenarios to provide highly reliable and secure connectivity over a wide geographical area. This book explores promising scenarios for 5G SatCom, novel paradigms for hybrid/integrated satellite-terrestrial integration, and emerging technologies for the next generation of SatCom systems. Topics covered include: Role of SatCom in the 5G Era; 5G satellite use cases and scenarios; SDN-enabled networks, NFV-based scenarios and on-board processing for satellite-terrestrial integration; EHF broadband aeronautical SatCom systems; Next-generation NGSO SatCom systems; Diversity combining and handover techniques for MEO satellites; Non-linear countermeasures for multicarrier satellites; SDN demonstrator for multi-beam satellite precoding; Beam-hopping SatCom systems; Optical on-off keying data links for LEO downlink applications; Ultra-high speed data relay systems; On-board interference detection and localization; Advanced random access schemes for SatCom systems; Interference avoidance, mitigation and dynamic spectrum sharing for hybrid satellite-terrestrial systems; and Two-way satellite relaying.
Inspec keywords: radiowave propagation; radio spectrum management; mobile satellite communication; 5G mobile communication; interference suppression
Other keywords: onboard processing systems; propagation aspects; system-level techniques; 5G SatCom; satellite communications; physical-level techniques; latency reduction techniques; integrated satellite-terrestrial systems; optical technology-based satellite systems; advanced collision-interference mitigation; spectrum sharing
Subjects: Electromagnetic compatibility and interference; Mobile radio systems; General electrical engineering topics; Satellite communication systems
- Book DOI: 10.1049/PBTE079E
- Chapter DOI: 10.1049/PBTE079E
- ISBN: 9781785614279
- e-ISBN: 9781785614286
- Page count: 500
- Format: PDF
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Front Matter
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1 Role of satellite communications in 5G ecosystem: perspectives and challenges
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The next generation of mobile radio communication systems - so-called 5G - will provide some major changes to those generations to date. The ability to cope with huge increases in data traffic at reduced latencies and improved quality of user experience together with a major reduction in energy usage are big challenges. In addition, future systems will need to embody connections to billions of objects - the so-called Internet of Things (IoT) which raises new challenges. Visions of 5G are now available from regions across the world and research is ongoing towards new standards. The consensus is a flatter architecture that adds a dense network of small cells operating in the millimetre wave bands and which are adaptable and software controlled. But what is the place for satellites in such a vision? The chapter examines several potential roles for satellites in 5G including coverage extension, IoT, providing resilience, content caching and multi-cast, and the integrated architecture. Furthermore, the recent advances in satellite communications together with the challenges associated with the use of satellite in the integrated satellite-terrestrial architecture are also discussed.
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2 Satellite use cases and scenarios for 5G eMBB
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This chapter presents initial results available from the European Commission H2020 5G PPP Phase 2 project SaT5G (Satellite and Terrestrial Network for 5G) [1]. It specifically elaborates on the selected use cases and scenarios for satellite communications (SatCom) positioning in the 5G usage scenario of eMBB (enhanced mobile broadband), which appears the most commercially attractive for SatCom. After a short introduction to the satellite role in the 5G ecosystem and the SaT5G project, the chapter addresses the selected satellite use cases for eMBB by presenting their relevance to the key research pillars (RPs), their relevance to key 5G PPP key performance indicators (KPIs), their relevance to the 3rd Generation Partnership Project (3GPP) SA1 New Services and Markets Technology Enablers (SMARTER) use case families, their relevance to key 5G market verticals, and their market size assessment. The chapter then continues by providing a qualitative high-level description of multiple scenarios associated to each of the four selected satellite use cases for eMBB. Useful conclusions are drawn at the end of the chapter.
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3 SDN-enabled SatCom networks for satellite-terrestrial integration
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Key features of satellite communications such as wide-scale coverage, broadcast/multicast support and high availability, together with significant amounts of new satellite capacity coming online, anticipate new opportunities for satellite communications services to become an integral part of upcoming 5G systems. This chapter examines the realization of end-to-end (E2E) traffic engineering (TE) in a combined terrestrial-satellite network embracing software-defined networking (SDN) technologies. The focus is placed on a mobile backhaul network scenario where a satellite component is used to complement the terrestrial infrastructure in a way that E2E paths across both satellite and terrestrial links can be centrally computed and rearranged dynamically at flow-level granularity in front of link congestion and failure events. The chapter describes the architecture of such SDN-enabled satellite ground segment system and presents illustrative TE workflows. Furthermore, sustained in the proposed architectural framework, an SDN-based TE application for hybrid satelliteterrestrial backhaul networks is developed and its performance assessed under diverse scenario conditions.
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4 NFV-based scenarios for satellite–terrestrial integration
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This chapter focuses on this issue, reviewing the applicability of cloud networking technologies to satcom platforms and determining the benefits and the challenges associated with the integration of satellite infrastructures into future cloud networks.
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5 Propagation and system dimensions in extremely high frequency broadband aeronautical SatCom systems
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The potentialities of using EHF frequencies on a satellite for aeronautical broadband communication provision have been discussed in this chapter. Currently used Ka band frequencies will soon not be able to cope with the increased Internet demands from aircraft passengers. There do not appear to be any major regulatory barriers to adopting Q/V and W bands, except perhaps around airports. It has been shown that the propagation impairments in the troposphere that are preventing for now the use of those bands for satellite user links are not a major issue for aeronautical applications as the magnitude of those impairments is significantly decreasing with altitude. They are almost negligible at cruise level. The various tools available to size the propagation margins have been detailed. An outcome of the analysis is that the margins required to ensure more than 99.9% of availability could be lower than 10 dB for most of the flight configurations at Q/V and W band. In order to get an idea of the improvement of the performances brought by the use of those higher frequency bands, current aeronautical terminals and satellites characteristics' have been extrapolated to EHF. It has been shown that the capacities provided can be enhanced by use of conformal antennas and provide from 4 to 10 times increases over current Ka band systems. These would appear to accommodate the predicted requirements of around 200Mbps per aircraft made for 2020 and beyond. This demonstrates the feasibility of EHF satellite systems to meet future Aero passenger requirements, letting bandwidth for ground-based applications at lower frequency bands.
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6 Next-generation non-geostationary satellite communication systems: link characterization and system perspective
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In this book chapter, the next-generation NGSO satellite communication systems and the propagation link characteristics induced are presented and discussed. NGSO satellite systems are not a very recent idea, since NGSO systems have been operating since the end of the 1990s of the previous century. In Table 6.3, the advantages and disadvantages of NGSO systems in comparison to GSO networks are briefly given. The advantages of NGSO systems are the lower latency, smaller size and lower losses in comparison to GEO satellite systems and that when a constellation is shaped a global coverage can be achieved. Now, new systems have been put in operation and are planned which are using NGSO satellites. The next-generation systems will make use of the high-frequency bands and higher data rates could be delivered. Depending on the application, service provided and kind of link (feeder or user links), different frequency bands will be used. Different bands experience different propagation characteristics. Lower bands (L-/S-bands) are mostly affected by the local environment while in high-RF bands and optical range, atmospheric effects must be considered for the system design. Moreover, the use of fade mitigation techniques, such as ACM or diversity techniques, increase system's throughput and availability as has been shown in recent studies. However, an issue which must be tackled is the inter-system interference not only for the NGSO and GEO systems but also for the different mega-constellations, if all these planning systems will be set during launch and operation.
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7 Diversity combining and handover techniques: enabling 5G using MEO satellites
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In this chapter, we provide a thorough review of medium Earth orbit (MEO) satellites, highlighting their applications, peculiarities, and the role that they may play in the implementation of 5G for satellite networks. In particular, we will explain why MEO satellites are a new paradigm, how to tackle the challenges related to their usage, and how they fit into the 5G context. In this perspective, we will show how diversity combining and handover are key functionalities for their successful integration. Towards describing the 5G paradigm with MEO satellites, the chapter first provides a high-level description of the satellite characteristics, the services that have been deployed, and also possible future applications. Further, a high-level description of all the atmospheric effects affecting typical MEO communications is included. Finally, a critical review of handover techniques (state-of-the-art, trade-offs, and future challenges), as well as a review of combining techniques (theoretical performance in a MEO scenario, advantages, drawbacks, and trade-offs), will be presented.
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8 Powerful nonlinear countermeasures for multicarrier satellites: progression to 5G
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The exigent demand for transmitting high data rates over satellites, coupled with the challenge to maximize satellite mass efficiency, has necessitated that multiple carriers with high-order modulation share the same transponder's high-power amplifier (HPA) that is operated close to saturation. Several powerful technological solutions, applied at the transmitter, in the form of predistortion, and at the receiver, in the form of equalization, are explored in this chapter to minimize the resulting nonlinear distortion. To establish greater commonality with the emerging fifth-generation (5G) ecosystem, the second part of this chapter endeavors to apply orthogonal frequency-division multiplexing (OFDM) signaling for broadband satellite transmission in the forward direction, namely, from the gateway to terminals. 5G terrestrial systems continue to use OFDM air interface. The aforementioned powerful countermeasures are then generalized, utilized, and shown to exhibit excellent performance in allowing OFDM-based satellite systems to be competitive with, and in some cases surpassing, traditional systems that use single-carrier modulation (SCM) when employing high-order constellations and/or having multiple signals share the same transponder.
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9 Satellite multi-beam precoding software-defined radio demonstrator
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The aim of this chapter is to demonstrate the ability of broadband multi-beam satellite systems to operate in aggressive frequency reuse modes, enabled by advanced signal processing methods, namely precoding, when practical constraints affects the implementation of signal processing techniques. To accomplish the objective, a specific hardware infrastructure composed by properly interconnected software-defined radios (SDRs) has been built. The infrastructure is able to emulate a satellite forward (FWD) link transmission using a GW emulator and a multi-beam satellite channel emulator, which includes, on top of the satellite impairments, the multiple-input-multiple-output (MIMO) user link channel and a set of independent UTs radio frequency (RF) impairments emulators. To enable real-time precoding implementation, a feedback channel from UTs to the GW is emulated accordingly. The general infrastructure includes a various number of SDR development platforms called universal software radio peripherals (USRPs), each of them connected to a central hub used for selecting the sub-infrastructure required for the specific test, while also providing control and monitoring functionalities. Each board is itself a single-antenna/multi-antenna system equipped with a RF module, digital-to-analog (DAC) and analog-to-digital converters (ADC) and a high performance FPGA for user-defined digital processing. The central hub is also supported by a high computational capabilities workstation equipped with a set of FPGAs, used for the centralized processing.
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10 Beam-hopping systems for next-generation satellite communication systems
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In this chapter, the concepts and benefits of beam-hopping were presented along with some detection performance considerations. In particular, the gains in user satisfaction and system usable throughput were compared to that of a conventional broadband satellite system with a static coverage. Complementing the beam-hopping system principles, we discussed the physical layer transmission solutions suitable for beamhopping. Based on the identified waveform key-requirements for applying beamhopping, the already released DVB-S2X standard was reviewed and analysed using practical and representative system examples. It was found that the super-framing specification offers high practical relevance compared to the conventional DVBS2/S2X framing. The author also presented actual and future technology for a beam-hopping systems. Specifically, the upcoming Eutelsat Quantum-class satellite designed for beamhopping was presented along with its features like re-configurable beam-forming and highlights potential applications. The corresponding ground equipment was also discussed exploiting the advantages of wideband processing. Furthermore, implementation feasibility has been demonstrated by means of detection performance results exploiting DVB-S2X SF Format 4. Beam-hopping offers flexible system architecture to address changing traffic demands over time and geographical locations by sharing in time, power and frequency resources among multiple beams. Beam-hopping systems offer higher usable throughput by focusing the system resources where they are most needed at a time.
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11 Optical on–off keying data links for low Earth orbit downlink applications
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Within this chapter, high-speed optical satellite data downlinks have been reviewed and the key characteristics of this application scenario have been described. The excellent properties of optical links, especially the high data rate, license free operation and favourable SWaP (size, weight and power) provide a game-changing technological alternative to RF-links for Earth observation satellite operators. Despite some drawbacks of the technology, industries and research organisations around the world are now developing optical communication systems that are suitable for downlink applications, demonstrating the potential of the technology and underlining its future importance for various applications.
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12 Ultra-high-speed data relay systems
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The objective of this chapter is to define and analyze the key elements in the design of future ultra-high-speed relay systems based on optical technologies.
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13 On-board processing for satellite-terrestrial integration
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Flexibility in satellites is one of the major requirements to make use of them in the 5G environment. A key method to achieve this goal is on-board processing. Satellites have become more and more flexible in recent days, started by the development years ago with the development of digital transparent processors to gain flexibility in frequency and channel allocation. First, this chapter gives a brief history of on-board processers (OBPs) followed by a classification of OBPs. For illustration, the current design of the Fraunhofer OBP (FOBP) is described followed by an exemplary 5G use case for OBP using low-earth orbiting (LEO) satellites. The chapter closes with a short summary.
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14 On-board interference detection and localization for satellite communication
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Interference is identified as a critical issue for satellite communication (SATCOM) systems and services. There is a growing concern in the satellite industry to manage and mitigate interference efficiently. In this context, an on-board spectrum monitoring and localization unit can be used to detect and localize the interference reliably. Current satellite spectrum monitoring and localization units are deployed on the ground, and the introduction of an in-orbit spectrum monitoring and localization unit can bring several benefits, e.g., simplifying the ground-based station in multibeam systems. This chapter presents the interference detection and localization techniques which take place on-board the satellite within a digital transparent processor (DTP) satellite payload or in a partially regenerative satellite. First, the conventional energy detector (CED) is presented, which is an efficient technique to monitor strong interference in SATCOMs. However, weak interference is not so easily detectable because of its low interference-to-signal-plus-noise ratio (ISNR). To address this issue, a second detector is discussed, which exploits the frame structure and pilot symbols of the SATCOM standards. Assuming that the pilot signal is known at the receiver, it can be removed from the total received signal, and then, an ED technique can be applied on the remaining signal to decide on the presence or absence of interference. Nevertheless, the detection at low values of ISNR may require more samples than the number of pilots supported by the standards. For this reason, a third detector is introduced by demodulating the desired signal, removing it from the total received signal and applying an ED in the remaining signal for the detection of interference. After detecting the interference, the interferer needs to be localized and, hence, this chapter describes the current techniques for on-ground interference localization and presents an on-board interference localization technique using frequency of arrival (FoA) via a single satellite.
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15 Random access in satellite communications: a background on legacy and advanced schemes
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This chapter presents a background on the various legacy and advanced RA techniques proposed for satellite communications. First, we describe the main motivations for enhancing RA performance on the return link. Then, we present a list of legacy RA techniques used mostly for login purposes. Furthermore, we provide another list describing the recent RA techniques with enhanced performance due to data replication and additional signal processing at the receiver side. These recent RA schemes can be mutually used for login as well as data transmissions over the return link. Finally, we give a global comparison of the performance of enhanced RA and we discuss the application of each scheme with respect to system constraints such as power limitations, lower data rates and synchronisation overhead reduction.
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16 Interference avoidance and mitigation techniques for hybrid satellite-terrestrial networks
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In this chapter, we described interference avoidance and mitigation techniques for hybrid satellite-terrestrial MBH systems. More specifically, we considered a hybrid backhaul setup where the satellite segment off-loads the terrestrial one and enhances the overall capacity of the system. Moreover, we assumed that these two segments share the same spectrum, in order to utilize more efficiently this scarce and expensive resource. In addition, in the proposed system, the backhaul nodes are equipped with antenna arrays instead of drum antennas and make use of multiantenna communication techniques.
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17 Dynamic spectrum sharing in hybrid satellite–terrestrial systems
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The focus of this chapter is on dynamic spectrum sharing in hybrid satellite-terrestrial systems. We start by classifying the scenarios for these systems. The most important dynamic spectrum-sharing techniques such as spectrum sensing, databases, beamforming, beam hopping, and adaptive frequency and power allocation are discussed and their applicability in different scenarios is analysed. Interference analysis shows how Ka band sharing between satellite and terrestrial systems can be enabled. Autonomous ships are defined as an interesting emerging application area for hybrid satellite-terrestrial systems. In order to make them operate reliably and safely both close to shoreline and in deep sea, multiple communication technologies are needed. Interference management and spectrum-sharing techniques could be used, e.g. to prevent blocking or hijacking of the control signalling of a ship. In addition, we discuss shortly the citizens broadband radio service (CBRS) concept in the 3.5-GHz band. Ideas to use CBRS and other database techniques in millimetre wave bands to enable spectrum sharing between satellite and terrestrial components of a future 5G system are given.
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18 Two-way satellite relaying
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We have discussed the problems associated with the TWSR in this chapter. A training protocol for the TWSR system has been discussed and studied in detail. This training protocol is used to estimate the CSI required for self-interference cancellation and symbol decoding with sufficiently low estimation noise. Performance of this training-based scheme has been analysed in terms of BER and average capacity. Then, differential modulation-based TWSR has been discussed. The use of differential modulation allows for obtaining a differential detector which does not require any channel information in the destination ES. This useful virtue of the proposed differential detector allows for avoiding the difficulty of channel estimation in two-way AF satellite communication. Further, two beamforming and combining schemes for TWSR have been discussed in this chapter. In first scheme, the calculation of beamforming and combining vectors has been performed by utilizing local channels of ESs, whereas second scheme is SNR optimal and the beamforming and combining vectors have been calculated by using maximum eigenvalue criterion. It can be concluded that SNR optimal beamforming and combining outperforms the local channel-based beamforming and combining scheme. All the presented schemes are very useful for practical implementation of TWSR communication systems.
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Back Matter
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