Advances in Communications Satellite Systems Proceedings of The 36th International Communications Satellite Systems Conference (ICSSC-2018)
The International Communications Satellite Systems Conference (ICSSC) is one of the most influential technical conferences in the field. The 36th edition was held in October 2018 in Niagara Falls, Canada. These proceedings present a broad spectrum of space communications topics from the conference, from the evolution of GEO from traditional area coverage to Ultra High Throughput Satellites (UHTS), the growing number of mega constellations expected to enter service in the next decade, navigation applications such as vehicle autonomy, wideband data backhaul from scientific and remote sensing payloads in LEO, and the extension of the 5G network to near earth, lunar and deep space environments in support of human exploration.
Inspec keywords: artificial satellites; multibeam antennas; correlation methods; radio spectrum management; radio links; cognitive radio; frequency division multiple access; radiowave propagation; adjacent channel interference; matrix algebra; telecommunication network planning; optimisation; telecommunication switching; space communication links; amplifiers; modulation; antenna phased arrays; telecommunication equipment testing; mobility management (mobile radio); cooperative communication; satellite navigation; broadcast communication; satellite ground stations; telecommunication standards; cloud computing; telecommunication computing; Mars; transponders; 5G mobile communication; signal detection; spread spectrum communication; precoding; Internet; bandwidth allocation; satellite communication; diversity reception; rain; software defined networking; wireless channels; interference suppression; packet radio networks; broadband networks; Moon; learning (artificial intelligence); optical communication
Other keywords: maritime Earth station; ICSSC-2018; rate-splitting approach; wideband nonlinearities correction; systematic optical data transfer; overlapping clustering; nonlinear HPA; mobile satellite systems; beam-hopping systems; adjacent beams resource sharing; multibeam UHTS; modular architecture; DVB-S2X super-framing; interference mitigation techniques; high data rate ground-to-satellite optical links; Sentinel-2A/B; interference protection; data throughput maximization; cislunar communications; flexible high data rate transmitter; Ka-Band; Earth observation space systems; VHF data exchange systems; over-the-air packet communications; Sentinel-1A/B; distributed precoding; DVB-RCS2 standard; rain fading channels; VDES satellite downlink component; 5G edge caching; robust initial access technique; flexible payload; diversity architectures; digital payloads channels; feeder links; block level precoding; EDRS; SC-FDMA subcarrier switching; mobile application; timeslicing transmission; flexible optical ground network operations; multiport amplifiers; system level modelling; earth observation satellite to ground transmission; hot spots; RF architectures; business modelling; mars; VHF radio channel; satellite backhaul; machine learning based modulation scheme; interference management; cognitive communications; navigation infrastructure; communications satellite systems; V-band low-noise amplifier module; spread spectrum; asynchronous cooperative NOMA capacity; satellite cognitive communication networks; mobile station; imperfect Butler matrices; time diversity gain; Alphasat; interactive satellite networks design; Ka-band mobile satellite communication; adaptive onboard compensation; GNURadio; cots-based software-defined communication system platform; 5G satellite networks; multibeam satellite systems; spectrum sensing algorithm; symbol level precoding; bandwidth efficient techniques; linearized transponders; productized multicarrier predistortion; NORSAT-2 satellite experiment; VLEO satellites; true customer use cases; linearized channels; capacity enhancement; VDE-SAT; EHF links; beam-hopping over-the-air tests; effective data downlink; rateless codes; high speed optical communications; mobility enhancement; parallel architectures; cloud computing; channel states information; moon; low cost phased array antenna; precoded communications; overlapping coverage areas; flexible high throughput satellite systems; adjacent channel interference; VSAT; satellite data exchange system; time correlation; multicarrier transmission; Internet for Space; X-Band; LEO applications; satellite payload design; DRRM communications; total throughput gains; rainfall prediction; autonomous bandwidth allocation scheme; propagation channel optimization; VHTS systems; International Communications Satellite Systems Conference; Earth observation missions; digital video satellite broadcast networks; research and development approach; adaptive resources allocation
Subjects: Signal processing and detection; Amplifiers; Communication system theory; Antennas; Modulation and coding methods; Radio links and equipment; Radiowave propagation; General and management topics; Algebra; General electrical engineering topics; Knowledge engineering techniques; Algebra; Communications computing; Electromagnetic compatibility and interference; Aerospace; Telecommunication applications; Optimisation techniques; Optimisation techniques; Optical communication; Information networks; Radionavigation and direction finding; Computer networks and techniques
- Book DOI: 10.1049/PBTE086E
- Chapter DOI: 10.1049/PBTE086E
- ISBN: 9781785619618
- e-ISBN: 9781785619625
- Page count: 351
- Format: PDF
-
Front Matter
- + Show details - Hide details
-
p.
(1)
-
Section 1 – Multi-beam Satellite Systems
1 Symbol vs block level precoding in multi-beam satellite systems
- + Show details - Hide details
-
p.
3
–9
(7)
Precoding techniques for mulit-beam satellite systems have received a considerable attention in recent years as a tool to mitigate the interference among the beams, and hence increasing the throughput. Our goal is to compare two main categories of precoding schemes, namely, the conventional linear block level precoding and the symbol level precoding. Focusing on power minimization problem with signal to interference plus noise ratio (SINR) constraints, symbol level precoding (SLP) has significant gains with respect to the zero forcing (ZF). However, the lower transmit power is achieved with a price: A higher computational complexity. Therefore, several sub-optimal SLP techniques have been proposed in the literature to overcome the complexity. While ZF has the lowest complexity among the techniques chosen in this paper, it is not an optimal linear block level precoder as far as power minimization is concerned. Therefore, in order to have a more complete picture, one needs also to consider optimal block level precoders. Our results indicate that in order to have a fair comparison, one needs to consider two different scenarios, namely, low and high SINR threshold regimes. While for low SINRs the optimal linear block level precoding scheme may provide a good solution with reasonable complexity, for high SINR threshold, the SLP techniques become more attractive. Our results also indicate that the performance of SLP highly depends on the chosen constellation space, and therefore a final conclusion can be achieved only after appropriately optimizing the constellation set.
2 Hardware Demonstration of Precoded Communications in Multi-Beam UHTS
- + Show details - Hide details
-
p.
11
–15
(5)
In this paper, we present a hardware test-bed to demonstrate closed-loop precoded communications for interference mitigation in the forward link of the multi-beam ultra-high throughput satellite systems. The hardware demonstrator is a full-chain closedloop communication system with a multi-beam DVB-S2X compliant gateway, a satellite payload, and MIMO channel emulator and a set of DVB-S2X user terminals with real-time CSI estimation and feedback. We experimentally show the feasibility of Precoding implementation in satellite communications based on the superframe structure DVB-S2X standard. Using the test-bed we have a possibility to run real-time precoded DVB-S2X communication and benchmark its performance under realistic environment. The hardware demonstrator is suitable to perform realistic benchmarks of Blockand Symbol-level Precoding techniques for multicast and unicast user scheduling scenarios.
3 On the capacity of asynchronous cooperative NOMA in multibeam satellite systems
- + Show details - Hide details
-
p.
17
–22
(6)
In this paper, we investigate the effect of asynchronous reception in multibeam satellite system forward link using our previously proposed cooperative non-orthogonal multiple access (NOMA) technique. Our proposed system is in a dense frequency reuse scheme and based on the cooperation of transmitting beams by targeting one user terminal at a time. The jointly reception of data streams features multiple access channel (MAC), where both data will be recovered by devising successive interference cancellation (SIC). Herein paper we show that in case of asynchronous reception, the propagation of errors through SIC causes huge loss of data frames and throughput degradation. Hence, we propose the channel model of the asynchronous NOMA, and we investigate the system's capacity region, where the information theoretic results show that the asynchronous reception of the data streams can indeed improve the sum-rate upper bounds.
4 Overlapping clustering for beam-hopping systems
- + Show details - Hide details
-
p.
23
–28
(6)
Beam hopping system sharing transmitting resources in time enables satellites and gateways to reduce their costs for increased HTS capacity. However, the conventional beam hopping system decreases frequency efficiency if the traffic demands vary among clusters because it shares their resources only in a cluster. Therefore, this paper proposes the novel beam hopping technique which overlaps each of clusters to share transmitting resources among them. The effectiveness of the proposal is verified through simulation results.
5 Adjacent beams resource sharing to serve hot spots: a rate-splitting approach
- + Show details - Hide details
-
p.
29
–36
(8)
This work addresses the uneven traffic demand scenario in multi-beam satellite svstems, in which a hot-spot beam is surrounded bv cold beams. After partitioning the hotspot beam in different sectors, resource pulling from cold neighbouring beams is allowed following an aggressive frequencv-reuse scheme. As a consequence, the level of the co-channel interference within the hot-spot beam increases. A scheme known as Non-Coherent Rate-Splitting (NCRS) is emploved to cope with this interference, based on the exclusive use of magnitude channel state information at the transmitter (CSIT). The receiver complexitv is increased with respect to full CSIT precoding schemes, which are considered for benchmarking purposes. Different NCRS strategies are analvzed and compared with several partial and full CSIT schemes. The proposed solution not onlv shows an improvement with respect to partial CSIT benchmarks, but also displavs a competitive performance against full CSIT precoders.
-
Section 2 – Cognitive Communications and Propagation Channel Optimization
6 Time Correlation Used to Improve Time Diversity Gain of Rainfall Prediction
- + Show details - Hide details
-
p.
39
–44
(6)
Correlation of the rainfall rate with time depends on geography, environment, and the type of rainfall. In this letter, we consider the use of such a correlation to improve the time diversity gain of a system that predicts rainfall over Japan. From a rain may with 4 years of data, we selected 43 locations throughout mainland Japan, and from these data, we derived the cumulative time percentage, the diversity gain from a time diversity method using 10 to 120 min delays, and the correlation from a time series of rainfall. This information is used to improve the prediction of rainfall. Root-mean-square errors show an improvement in the diversity gain.
7 Protection of the Mobile Station from the Interference by Maritime Earth Station in Motion in the 28 GHZ Band
- + Show details - Hide details
-
p.
45
–48
(4)
The Earth Stations in Motion (ESIM) system are one of the most modern satellite systems, providing high-speed and high-capacity communication with mobility. ESIM in the Kaband should be operated under the condition ensuring the protection of existing services in the same frequency band. Therefore compatibility studies of ESIM with incumbent services in the same frequency band should be conducted before authorization, licence or operation of EISM. This paper provides a methodology to assess the interference from maritime ESIM to an MS stations in the 28 GHz frequency band. Taking into account a point-to-point interference scenario, the simulation results show the separation distances between maritime ESIM and MS station for protecting the MS stations. We considered the heights of station, elevation angle and time percentage in calculating the interference to reflect various factors affecting the interference level. The separation distance of up to 155 km would be required to ensure the protection of MS receiver taking the results of simulation into consideration.
8 Rateless codes for satellite systems over rain fading channels
- + Show details - Hide details
-
p.
49
–54
(6)
Modern satellite systems utilize high frequency bands usually above 15 GHz to provide high speed transmission services, and adopt adaptive modulation and coding (AMC) schemes in order to countermeasure serious rain fading occurred in the utilized frequency bands. This paper introduces an efficient scheme to countermeasure rain fading by using rateless codes. The proposed scheme utilizes existing AMC scheme with the LDPC codes, and thus it can be easily combined with existing standards. The error rate and spectral efficiency performance simulation results demonstrate performance enhancement over a satellite rain fading channel, with almost the same code rate as the existing LDPC codes.
9 Channel States Information based Spectrum Sensing Algorithm in Satellite Cognitive Communication Networks
- + Show details - Hide details
-
p.
55
–59
(5)
This paper proposes a spectrum sensing algorithm based on channel states information to solve the problem of the instantaneous power drop of the signal in the satellite cognitive network. The proposed algorithm adds an update mechanism in the traditional energy detection process and maps the current channel state statistic by using the channel statistics of the previous detections. This algorithm is studied in the satellite cognitive network scenario, in which GEO satellite network is primary user, LEO satellite network is secondary user. Moreover, a spectrum sensing model is built to help study this algorithm. Simulation results show that the proposed algorithm significantly improves the efficiency of spectrum sensing and solves the problem that the power of the signal to be detected is constantly changing due to shadow effect.
10 Wideband nonlinearities correction in digital payloads channels with parallel architectures
- + Show details - Hide details
-
p.
61
–65
(5)
The problem domain related to the correction of wideband non-linearities on satellite receiving or transmitting chains is more and more increasing due to the need of satellite missions with high throughput data handling, high precision accuracy and high energy efficiency. Typical non-linear distortions could be introduced by different active on-board devices in the RX/TX chains such as LNA, mixers, active filters, A/D and D/A converters and high power amplifiers (in low back-off operations). Modeling wideband distortions requires the introduction of memory effects, to account for more complex distortion mechanisms than static polynomial nonlinear models. In multi-channel (beam-forming) receivers/transmitters, especially if wideband, the data rate increases with the number and bandwidth of channels, and so does the need for hardware resources. Generalized models based on Volterra kernels are hardware-consuming, especially when applied for wideband systems with high data rates and potentially long memory effects. In this paper the architecture of a Volterra filter, adapted in order to exploit high parallelism in a possible target space hardware, is presented, taking into account the design constraint to keep digital complexity to a minimum by using a priori (restricted models) or a posteriori (pruning) techniques for complexity reduction and low power exploitation. Finally, the implementation of this filter performed on a many-core processors technology, in order to achieve high throughput performances on beam-forming and wideband systems, is evaluated in terms of computational cost and I/O, taking into account data rates, memory requirements, data dependencies, and raw processing power.
-
Section 3 – Flexible High Throughput Satellite Systems and Interference Mitigation Techniques
11 Modifications to Multi-beam Systems for DRRM
- + Show details - Hide details
-
p.
69
–74
(6)
An initial study of the emergency communications services offered by current multi-beam satellite systems for disaster relief and rescue mission (DRRM) effort has been conducted within the frame work of DVB and LTE/5G in ETSI. A multi-beam communications satellite system with its unique coverage and beam hopping advantage can be adapted to provide DRRM communications services when and where the other communications services are absent. A proposal of using partial multi-beam system resources for the DRRM is made and a sample design of the digital analysis filter bank for the modified satellite transponder is presented and partially optimized.
12 Adaptive Resources Allocation for Flexible Payload enabling VHTS systems: Methodology and Architecture
- + Show details - Hide details
-
p.
75
–82
(8)
Very High Throughput Satellites (VHTS) are optimized satellite systems that will meet the demands on increasing data traffic. VHTS outperforms the capacity of traditional systems that provide FSS and MSS (Fixed and Mobile Satellite Services, respectively) which use contoured regional footprints. VHTS aims at achieving 1 Terabit/s per satellite in the near future, and are based on multi-spot coverage with frequency and polarization reuse schemes using larger bandwidths in the feeder link in the frequency Q/V bands or by optic links. These systems provide higher satellite links capacity with a reduced cost per Gpbs-in-orbit. Since traffic demand is not always the same in the service area and it may change over time, new flexible payload concepts are required. In this sense, this contribution presents the study of a flexible payload concept, the methodology for the adaptive algorithm to be used during the on-line or off-line processes for optimal resources allocation and the architecture for adaptive resources allocation as well with a set of preliminary results.
13 Adaptive Onboard Compensation of Non-Linear HPAs and Imperfect Butler Matrices in Multiport Amplifiers for High Throughput Satellites
- + Show details - Hide details
-
p.
83
–90
(8)
Multiport amplifier (MPA) is a key technology for future high throughput satellites (HTS) which aim at delivering extremely high data rates with flexible payloads. MPAs offer more flexible and efficient use of power onboard the satellite. This paper outlines two major issues which degrade the optimal MPA performance, i.e. the non-linear effects of high power amplifiers (HPAs) and the hardware imperfections in implementing input/output-hybrid Butler matrices (INET/ONET). Furthermore, a novel two-step technique to improve MPA performance is presented. The proposed technique compensates the imperfect INET/ONET in the first step and predistorts the non-linear amplifiers in the second step. Simulation results presented indicate that by implementing the proposed adaptive solution, we gain in the bit error ratio (BER) performance and the system robustness to hardware imperfections.
14 Distributed precoding for multiple satellite systems with overlapping coverage areas
- + Show details - Hide details
-
p.
91
–97
(7)
This study aims at designing precoding in multiple satellite multibeam systems with overlapping coverage areas where the multiple satellites have the same footprints and overlap in their coverage. Besides, high throughput full frequency reuse pattern among satellites is used. In such an architecture, the key objective lies in the collaboration between satellites and obtains: i) reliable multibeam infrastructure to serve unforeseen changes in the traffic demand through establishing supportive secondary satellites, ii) multiple satellites can provide service to higher spatial diversity by keeping the size of the payload affordable, iii) employing multiple satellites provides hardware redundancy to guarantee uninterrupted service delivery. However, intra-satellite and inter-satellite interference are the bottleneck of the whole network and employing interference mitigation techniques, particularly precoding techniques, is essential. In this paper, we analytically and numerically study designing precoding technique that: a) properly mitigates intra-satellite and inter-satellite interference, b) since the performance of precoding is sensitive to the quality of Channel State Information (CSI), proper low complex CSI exchange mechanism among the satellites is developed.
15 Productized Multicarrier Predistortion Total Throughput Gains around 20£ over Linearized Channels in True Customer Use Cases
- + Show details - Hide details
-
p.
99
–103
(5)
Efficiency gain is a relevant metric of communication technology directly translating to the same improvement in operational expenditures while sometimes also allowing capital expenditure gains. The latest and best known multicarrier predistortion techniques for satellite communications yielding significant guaranteed throughput gains for all the receivers, regardless of the link budget, even over linearized transponders, have now been productized, tested over the Avanti satellite Hylas 4, and deployed, up to 500 MHz. This paper provides performance results for multiple use cases, including different number of carriers (1, 2, and 4 carriers), balanced and unbalanced power levels. For the relevant use case of two beams with unequal throughput requirements over a completely linearized transponder, total throughput gains around 20% in a single transponder have been achieved. We expect a continued and significant roll-out of this technology in the next 5 years, as long as the carriers in the forward of a high throughput satellite link follows a fixed carrier plan.
16 A mitigation technique for adjacent channel interference in communication satellites
- + Show details - Hide details
-
p.
105
–108
(4)
Adjacent channel interference is one of the major impairments that reduces achievable capacity in communication satellites, especially in high capacity throughput satellites (HTS) with densely packed spot beams. Adjacent channel interference (ACI) arises due to leakages in channel filters in any satellite repeaters. Because all filters are finite response filters, adjacent channel interference is always present. The most common technique to suppress ACI is to design multi-pole Butterworth filters with very steep roll-offs and thus very low leakages. However, the steeper the filter is, the higher its insertion loss will be, and the more expensive it will get. A very simple and low cost technique to suppress ACI is presented here. The technique is based on optimizing carrier assignment scheme to users in a ground system. The proposed technique allows maximum bandwidth usage without ACI impairment thus maximizing the achievable capacity throughput in any communication satellite system.
-
Section 4 – New Satellite System Architectures and Components
17 Novel RF architectures and technologies for VSAT
- + Show details - Hide details
-
p.
111
–116
(6)
Very Small Aperture Terminal (VSAT) systems provide satellite communication solutions for users where terrestrial technologies are either uneconomical or simply non-existent. VSAT ground terminals conceived to date are largely based on conventional RF architectures, which make use of bulky, high power and/or costly components. The continuous downwards pressure on the price and form factor of VSAT terminals requires a major evolution of the associated RF hardware - in terms of higher packaging density, lower power dissipation and optimized frequency stability. This paper describes the recent developments in the field of ground segment RF architectures and technologies and provides an overview of relevant R&D opportunities for VSAT terminals.
18 A Modular Architecture for Low Cost Phased Array Antenna System for Ka-Band Mobile Satellite Communication
- + Show details - Hide details
-
p.
117
–121
(5)
A low-cost and low profile phased array antenna system based on a modular approach is being developed for Ka-band mobile SATCOM applications. A Transmitter (TX) antenna array has been designed to provide the required circular polarized (CP) radiation beam with sufficient gain and a radiation pattern that satisfies the standard (FCC) emission mask. In the proposed modular approach, the intelligent active phased subarray (module) is designed and used as a building block to construct the whole array in any form and any size in any customized platform. In this design, the size of the intelligent subarray is chosen to be 4×4 with half-wavelength separation between the elements for both TX (30 GHz), and RX (20 GHz) array antennas. Larger array antenna with a few thousands of radiating elements can be formed by assembling as many modules as required on one platform. This paper discusses the modular approach aspects and its application in large scale phased array antenna implementation. Super TX / RX array modules of 256 elements are assembled and tested successfully to validate the proposed modular architecture. The measured radiation patterns at 30/ 20 GHz shows that the antenna's main beam can be steered to ± 70° in both azimuth and elevation directions.
19 A cots-based software-defined communication system platform and applications in LEO
- + Show details - Hide details
-
p.
123
–127
(5)
We present a complete, small form-factor, modular, and flexible software-defined radio communications platform based on carefully selected automotive-grade commercial off-the-shelf (COTS) components. The hardware consists of three credit-card sized modules for software-defined radio signal processing, computing and network processing, and power conditioning, as well as a multibeam active phased array antenna module. Requiring only unregulated spacecraft power supply and a data connection, the platform delivers electronically steerable and programmable radio communications links including encryption, physical-layer and network processing, channelization, and radio-signal conditioning within a low profile, modular, and scalable system. In addition, the platform may host application-specific payload processing tasks using available computing resources and reconfigurable hardware. The combination of programmability and small form factor allows for various use cases ranging from LEO satellites via UAVs and aircraft to missiles.
20 V-band low-noise amplifier module for high throughput satellite applications
- + Show details - Hide details
-
p.
129
–133
(5)
This paper presents the final test results of the Low-Noise Amplifier (LNA) module developed in Thales under a contract with the European Space Agency (ESA) operating in the frequency range 47.2 to 51.6 GHz. The LNA, featuring an unsurpassed noise figure of less than 2.8dB all over the band, is a complete Engineering Model (EM), ready to be employed as a front-end in advanced Q/V band payload on board of modern High Throughput Satellites (HTS). It provides 45 dB of gain automatically compensated in temperature (range -30 to +65 °C) and high linearity, performing a third order intercept point (IP3) of 24dBm with a power consumption of 870 mW. All the MMICs composing the line-up have been fabricated in Europe by using the recently space qualified process 0.1μm GaAs PHEMT provided by UMS.
21 Satellite payload design for cislunar communications
- + Show details - Hide details
-
p.
135
–142
(8)
This paper presents the design and performance of a communications payload module equipped with dedicated antennas for K-band, UHF and S-band links, which is envisaged as part of a possible future satellite constellation. The proposed design enables high availability and high capacity digital communication links between the Moon and Earth for a wide range of lunar missions; manned and unmanned, orbiters (including cubesats), landers, sample return vehicles, and includes compatibility to missions such as Lunar Orbital Platform-Gateway and Orion.
-
Section 5 – High Speed Optical Communications and Feeder Links
22 Alphasat, Sentinel-1A/B, Sentinel-2A/B, and EDRS Paving theWay for Systematic Optical Data Transfer for Earth Observation Missions
- + Show details - Hide details
-
p.
145
–158
(14)
Since late 2013, Inmarsat operated Alphasat GEO communication satellite has been providing a reliable platform for the experimental activities of its 4 hosted Technical Demonstration Payloads (TDPs), procured and operated by ESA. Amongst them, TDP1 is capable to receive observation data from a lower orbit (LEO) spacecraft thanks to its Laser Communication Terminal (LCT), and route the data to ground via a Ka band RF link. With the launch of Sentinel-1A in April 2014, of Sentinel-2A in June 2015, of Sentinel-1B in April 2016, and of Sentinel-2B in March 2017 in their sun-synchronous orbits, an increasing number of in-flight companions for the ASA terminal were made available. Part of the Copernicus program, the Sentinel satellites perform their earth observation missions thanks to a Synthetic Aperture Radar (S1A and S1B) and a Multi-Spectral Imager (S2A and S2B) respectively, and carry on board an Optical Communication Payload, based on the same TESAT LCT embarked on Alphasat. An Optical Inter-Satellite Link demonstration campaign in late 2014 with ASA and S1A using lead to the first data transmission from S1A in November 2014. The campaign was completed with results well beyond expectation in terms of link performances. Following the completion of the in-orbit commissioning of its Optical Communication Payload, S2A joined S1A in the following “Experimentation Phase”, aiming at the characterisation of the paired terminal performances over its operational envelope, that has been going on since the beginning of 2015. S1B and recently S2B have also been used as companion to Alphasat TDP1 terminal for their in orbit testing and calibration activities in the light of their commissioning into the now operational European Data Relay Satellite system. The Alphasat and Sentinels experience has provided the ultimate demonstration of the technology underlying the EDRS, and also made available an important opportunity to test the system operations in a realistic scenario and gain valuable experience to be put to fruition for the EDRS GS and operations, as well as for any future optical intersatellite communication system.
23 Diversity Architectures for High Data Rate Ground-to-Satellite Optical and EHF Links
- + Show details - Hide details
-
p.
159
–167
(9)
Architectural framework for next-generation satellite and ground terminal nodes using optical and EHF links will require diversity, redundancy, and network layer switchover designs to efficiently mitigate for signal losses due to atmospheric attenuation and scintillation. Our architecture leverages proven technologies, including Software-Defined Networking (SDN), Wavelength Division Multiplexing (WDM), linear programming optimization, and cost-effective IP/Ethernet packet processing within a unified network model. It is compatible with an agile and efficient control plane that is based on SDN OpenFlow (OF)-based link state measurements, centralized traffic route determination to address optical link fading, and standardized OF-based configuration of commodity hardware. Baseline and contingency traffic routing plans are used for rapid configuration of satellite payload, gateway and ground network nodes to leverage a make-before-break approach for dealing with high data rate link failures. This architectural framework is based on a linear algebraic traffic transport model with the following features: diversity gateway sites, proactive switchovers, optimal traffic routing, traffic engineering per traffic class, and optimized capital and operational costs. The next-generation systems with optical links can thus leverage cost-effective software and networking technologies, scalable cloud computing for optimal routing, and mature SDN protocols that can reduce the overall network implementation risks and costs.
24 Research and development approach to realize flexible opticalground network operations for effective data downlink from space to ground
- + Show details - Hide details
-
p.
169
–175
(7)
The application of optical communications technology for intersatellite and direct links is increasing in the fields of remote sensing and space explorations. Optical communication experiments have been conducted internationally and there are plans to use related technologies for space operations. However, there are not many experiments or plans for the network of optical ground stations focused on the particular issue of how to avoid cloud blocking in optical links between space and the ground for effective data downlink. In 2015, JAXA reported on a future experimental plan for optical direct communication links from space to ground in order to acquire the fundamental technologies of spatial pointing and tracking with the International Space Station and the experimental concept for the avoidance of cloud blockings by optical ground stations, cloud sensors and network planning systems [3]. To forward the study on flexible optical ground network operations, JAXA began joint research with Tokai University in 2017 and has studied more specific experiment method with ground fiber networks, cloud sensors, network planning systems and meteorological satellite data. This paper presents the research and development approach to realize flexible optical ground network operations for effective data downlink from space to ground.
-
Section 6 – VHF Data Exchange Systems
25 On the VHF radio channel for the data exchange system via satellite (VDE-SAT); experimental results from the NORSAT-2 satellite experiment
- + Show details - Hide details
-
p.
179
–186
(8)
Measurements of the Very High Frequency (VHF) downlink from NorSat-2 has been analysed in the context of development of the waveforms for VHF Data Exchange via Satellite. Received carrier, noise and interference power were analysed and compared with theory and simulations. The received power levels are as expected for most of the time. Slowly varying fading is observed with peak-to-peak variations in the order of 20 dB and a standard deviation of 4.2 dB. The fading has a close to normal distribution (in dB) and is mainly caused by sea reflections and to a lesser degree shadowing by the ship structure. Although time periods with significant interference were observed, most of the time the noise floor can be classified as residential or city according to ITU-R Rec. 372 on Radio noise. The noise plus interference level measured did not represent white Gaussian noise, and it is beneficial if the waveform(s) is robust with respect to both narrowband and wideband noise. The received C/N0 showed a dynamic range of about 25 dB, exceeding 34.7 dBHz for 95 per cent of time.
26 Field trials of the VHF data exchange system (VDES) satellite downlink component
- + Show details - Hide details
-
p.
187
–194
(8)
This paper focuses on analysing and characterising the communication channel of the VDES satellite downlink component by carrying out a measurement campaign of the VDE-SAT signal. The VHF downlink signal was transmitted from the Norwegian satellite NORSAT-2 operated by Space Norway. Three simultaneous carriers, specified in ITU-R M.2092-0, were transmitted in the test waveform: carrier 1 with BPSK/CDMA-8 modulation, carrier 2 with π/4 QPSK modulation and carrier 3 with 8PSK modulation. In addition, the satellite also transmits a CW carrier for test purposes. During this work a COTS-based receiver station has been designed, and installed on the roof of a house next to the sea. An embedded software application was implemented to automatically capture the test waveform every time the satellite was over the horizon. All the captured data was processed offline and the received waveform was thoroughly analysed, in order to assess the quality of the received signal and model the communications channel. The most relevant results derived from this work are presented in the paper.
-
Section 7 – Mobile Satellite Systems and Bandwidth Efficient Techniques
27 Mobility enhancement for digital video broadcast networks via satellite
- + Show details - Hide details
-
p.
197
–205
(9)
The DVB-S2 standard has been optimised for provision of broadband multimedia services to geographically dispersed fixed satellite end-users under line-of-sight (LOS) channel condition. However, continuing growth in demand for mobile broadband services via satellite necessitates a detailed examination of the DVB-S2 technology to assess its suitability for application in the mobile satellite environment. The environment is affected by signal fading due to path blockage, multipath propagation and shadowing, Doppler shift which is expressed by the Rician channel K-factor parameter values. In this paper, a model was developed in MATLAB® to simulate transmission scenarios through a mobile satellite channel, in order to investigate the bit-error-rate (BER) performance of the 16-APSK and 32-APSK modulation formats for different coding rates. This modelling of higher modulation formats of the DVB-S2 standard until now, has not been addressed adequately in related literature. Moreover, the mobility effect over the BER performance is not well investigated in the literature especially for high modulation schemes. Results obtained by simulation indicate a significant degradation in the system's BER when compared to a line-of-sight channel condition. Which even becomes worse with added varying mobility scenarios. However, higher Rician channel K-factor values tend to improve the link quality closer to that of the AWGN. These results highlight a crucial need to develop improved receiver processing and new switching thresholds applicable to the mobile satellite environment that deliver improved link availability as well as enhanced data throughput for different mobility scenarios.
28 System level modelling of DVB-S2X in high throughput satellite system
- + Show details - Hide details
-
p.
207
–210
(4)
DVB-S2X was published in 2014 to update and optimize the DVB-S2 specification, which was formulated ten years earlier. DVB-S2X offers increased efficiency and flexibility, enables the usage of advanced techniques, such as intra-system interference mitigation, beam hopping and multiformat transmissions, and more flexible SNR usage due to addition of high efficiency and more robust MODCODs. In this article, the system level model of DVB-S2X on top of Satellite Network Simulator 3 (SNS3) has been described and verified by means of simulations. It can be seen, that DVBS2X provides 13% gain in both peak spectral efficiency and burst throughput per user, while optimal channel condition with most efficient MODCOD may provide almost 40% gain in user throughput.
29 Demonstration of Autonomous Bandwidth Allocation Scheme using SC-FDMA subcarrier switching
- + Show details - Hide details
-
p.
211
–215
(5)
This paper introduces the Autonomous Bandwidth Allocation Scheme (ABAS) focusing on modulation/demodulation adopting SC (Single Carrier)-FDMA. In ABAS, which we have studied so far, each terminal station autonomously increases or decreases the frequency band in use according to the minimum common rule. This paper reports the overview of ABAS and its fundamental performance evaluation by developing the prototype of the SC- FDMA demodulator.
30 Robust initial access technique of spread spectrum based on DVB-RCS2 standard for mobile application
- + Show details - Hide details
-
p.
217
–221
(5)
In this paper, we deal with robust initial access scheme in spread spectrum mode for mobile DVB-RCS2 standard. For log-on process, it should be effective in terms of rapidity and reliability if we can utilize robust transmission and reception schemes under large timing and carrier frequency offset as well as very low SNR. Firstly, after we review the log-on burst transmission related with spread spectrum of DVBRCS2 specification under the harsh channel condition, we come up with the DVB-RCS2 tailored scheme that VSAT terminals should be able to support the reference waveforms. It's expected that it's applicable adaptively depending on channel condition to be considered.
31 Beam-hopping over-the-air tests using DVB-S2X super-framing
- + Show details - Hide details
-
p.
223
–229
(7)
The beam-hopping transmission concept has recently received a lot of attention due to a new level of flexibility to accommodate dynamic traffic profiles by employing the latest satellite technology. Based on the latest ground equipment developments of WORK Microwave and Fraunhofer IIS, beam-hopping system synchronization and control aspects have been tested over-the-air in June 2018. The network synchronization scheme as well as the ground equipment synchronization worked well and the performance goals have successfully been achieved.
-
Section 8 – Transmitter and Modern Technologies
32 Maximizing data throughput in earth observation satellite to ground transmission by employing a flexible high data rate transmitter operating in X-Band and Ka-Band
- + Show details - Hide details
-
p.
233
–238
(6)
Earth Observation (EO) and Intelligence, Surveillance and Reconnaissance (ISR) Systems equipped with High Resolution instruments are designed for high-performance operations in terms of fast revisit time, for very short system response time and for providing actionable intelligence with low data latency. The increased reliance on this data has created demand for decreasing latency. However, higher speeds and increasing bandwidth for data download are needed with the increasing numbers of satellites. At the same time, the scarce frequency resources especially in X-band (8.025 GHz to 8.4 GHz) but also in Ka-band (25.5 GHz to 27 GHz) call for more bandwidth efficient modulation schemes. This paper shares details regarding a new data transmission solution to efficiently use the available radio frequency (RF) bandwidth both in X-Band and Ka-Band by using Adaptive Coding & Modulation (ACM) as a key technology, allowing the volume of data to adapt to link budget characteristics. At the same time, high performance forward error correction coding such as SCCC and LDPC (DVB-S2) and high order modulation schemes (up to 64-APSK) are used, yielding both high power and spectrum efficiency. In terms of end-to-end performance, such sophisticated systems need to account for the ground station receiver characteristics. The proposed solution has therefore been verified using prototypes of both transmitter and receiver. Finally, a specific highly integrated transmitter design suited for smaller Earth Observation satellites down to SmallSats is presented.
33 Implementation of a Machine Learning Based Modulation Scheme in GNURadio for Over-the-Air Packet Communications
- + Show details - Hide details
-
p.
239
–245
(7)
In this paper we introduce an auto-encoder neural network that can be used to model a node-to-node radio frequency communication channel. With some simple assumptions the encoding layer of this neural network can be interpreted as a phase modulated signal which can be transmitted across a communication channel. When the auto-encoder is trained to minimize bit error rates within the transmitted messages, it effectively learns an optimal modulation scheme for that particular communication channel. To implement these signals in a physical link we developed GNURadio flowcharts along with custom signal processing blocks that transmit and receive the auto-encoder generated signals between a pair of Universal Serial Radio Peripherals. Finally, we show the methodology used for incorporating the GNURadio flowcharts with the auto-encoder training program so that the autoencoder can be trained on the physical communication channel itself.
34 An efficiency comparison between timeslicing and multi-carrier transmission for linearized transponders
- + Show details - Hide details
-
p.
247
–251
(5)
Very high throughput satellites (HTS), where single transponders have large bandwidths (in the order of 500 MHz), significantly reduced the cost per Mbit for satellite communications, and are therefore omnipresent for applications like broadband, mobile and enterprise connectivity. An HTS transponder can amplify single or multiple carriers. Single carrier transmission is still the most efficient mode in a nonlinear channel due its lower peak-to-average power ratio. In order to avoid too complex and expensive receivers, the wide carrier (around 500 MHz) is chopped in time slices such that receivers can decode their part of the very wide carrier. This crosslayer technology, applied for single carrier transmission, may bring overhead in some cases, also leading to some inefficiencies. In this paper, we will introduce and explain timeslicing and present a holistic efficiency comparison between single carrier transmission with timeslicing and multi-carrier transmisson without timeslicing, with and without non-linear predistortion. We conclude that Newtec non-linear predistortion (present in Newtec Equalink) with single or multi-carrier transmission outperforms single carrier transmission without non-linear predistortion. In addition, the throughput gain of single carrier transmission with respect to dual (four) carrier transmission is around 6% (9%) for linearized channels, the nowadays standard. Adding Newtec Equalink on top of single carrier transmission yields a total gain around 15% and 20% over dual and four carrier transmission without non-linear predistortion, respectively.
-
Section 9 – 5G and Satellite Networks Integration
35 Efficient 5G Edge Caching Over Satellite
- + Show details - Hide details
-
p.
255
–259
(5)
The fifth generation (5G) wireless networks have to deal with the high data rate and stringent latency requirements due to the massive invasion of connected devices and data-hungry applications. Edge caching is a promising technique to overcome these challenges by prefetching the content closer to the end users at the edge node's local storage. In this paper, we analyze the performance of edge caching 5G networks with the aid of satellite communication systems. Firstly, we investigate the satellite-aided edge caching systems in two promising use cases: a) in dense urban areas, and b) in sparsely populated regions, e.g., rural areas. Secondly, we study the effectiveness of satellite systems via the proposed satellite-aided caching algorithm, which can be used in three configurations: i) mono-beam satellite, ii) multi-beam satellite, and iii) hybrid mode. Thirdly, the proposed caching algorithm is evaluated by using both empirical Zipf-distribution data and the more realistic Movielens dataset. We show via numerical results that for the considered popularity data the multi-beam satellite will surpass the mono-beam system when the demands are less correlated, and that the hybrid achieves a cache hit ratio (CHR) between the multi-beam and mono-beam schemes.
36 Use cases to business modelling of satellite backhaul in 5G
- + Show details - Hide details
-
p.
261
–267
(7)
The H2020 project SaT5G [10] [13] is researching and developing the capability to seamlessly integrate satellite communication (satcom) backhaul links into 5G to support enhanced Mobile Broadband (eMBB). Four relevant use cases and a set of KPIs have been identified. A variety of different integration architectures are described. These factors have then been reviewed to allow business modelling for the new paradigms brought by 5G, and the role of a bandwidth broker has been identified.
37 5G technologies for a communications and navigation integrated infrastructure on moon and mars
- + Show details - Hide details
-
p.
269
–278
(10)
In the past years, ESA set forth the idea of a “Moon Village”, a village on the moon built by huge 3D printers and inhabited for months at a time by teams of astronauts. The plan outlined by the ESA is that, starting from the early 2020s, robots will be sent to the Moon to begin constructing various facilities, followed a few years later by the first inhabitants. Back in 2013, ESA teamed up with building companies to start testing out various Moon base-building technologies, and determined that local materials would be the best for constructing buildings and other structures, which means no need for transporting resources from earth at an astronomical cost. But the problems to be solved for the realization of such stable manned infrastructure on the Moon (a true follow-on of the International Space Station) involve much more than just building technologies. The Moon Village will be a large and complex system where requirements related to operations and safety of life will be of paramount importance. Moreover, from an architectural viewpoint the “village” will have to be expandable and “open” to the integration with other systems, hence integrability and expandability will be two key issues. But first and above all, the Moon Village will have to be affordable and sustainable, i.e., its cost will need to be assessed over its life-cycle. As a “Wild West” town in the old times, “Moon Village” will have to provide a number of essential infrastructures. In particular, the exploration of the Moon with human and robotic missions and its colonization, through the establishment of permanent bases, will require planetary communications and navigation infrastructures. The approach described in this paper was first presented in 2016 [1] and relies on the use of Commercial off-the-shelf (COTS) component for communication and navigation on the Moon surface. The use of LTE technology, currently deployed on Earth, and the coming 5G technology will allow communication and navigation, within the maximum throughput and the accuracy provided by the standard, assuming the implementation of all the basic pre-requisites on the Moon. More recently (March 2018), Vodafone and its technology partners Nokia, PTScientists, Audi and SpaceX announced their plan to set up the first cellular network node on the Moon. Because 5G is still in its very early stages, Vodafone has decided to go for the time being with 4G technology, using spectrum in the 1.8 GHz band. The Vodafone team intends to set up a base station near the Lunar Rover left in the Taurus-Littrow valley during the Apollo 17 mission and send to Earth live HD videos from the Moon's surface. The 4G network on the moon will connect two Audi Lunar Quattro rovers to a base station in the Autonomous Landing and Navigation Module (ALINA). This mission, planned for not earlier than 2019, would be the first private mission to the Moon. Esa's vision is much more ambitious, aiming at the creation of a permanent inhabited base on the Moon, with all the infrastructures needed to support life and operations.
-
Section 10 – Satellite Networks Design Challenges and Applications
38 Capacity enhancement and interference management for interactive satellite networks
- + Show details - Hide details
-
p.
281
–286
(6)
We investigate the effect of aggressive frequency reuse in multibeam satellite systems using novel techniques. The techniques include our previously proposed non-spreading non-orthogonal multiple access (NOMA) scheme as well as spread spectrum code division multiplexing (CDM) NOMA. The 4-color frequency reuse is used as benchmarks, while the 2-color 70-beam and 1-color 20-beam, exhibiting significant co-channel interference (CCI), were considered as interference-limited scenarios for comparative capacity performance evaluations. The operation accuracy of the successive interference cancellation (SIC) at the core of our interference mitigation (IM) techniques was also investigated. In terms of overall achievable capacity, the results show promising achievements in the 1-color 20-beam scenario while there are no capacity gains indicated in 70-beam scenario with 2-color frequency mapping. However, a significant fairness enhancement has been shown in both scenarios.
39 VLEO Satellites – a New Earth Observation Space Systems Commercial and Business Model
- + Show details - Hide details
-
p.
287
–297
(11)
Low earth orbits are defined as orbits with altitude below 2000km, these orbits provide superior advantages for earth observations missions. The distinction between VLEO and LEO is the altitude of the former is below 500km. VLEO missions possess great advantages such as, in maritime surveillance, illegal immigration and piracy this is due to the fact that the imagery capabilities are enhanced significantly and identification of small objects in the order of 1 meter is feasible, in addition to higher frequency of intraday location inspection visits. These are some of the great benefits for home land security and national security of any country.
40 Towards the Internet for Space: bringing cloud computing to space systems
- + Show details - Hide details
-
p.
299
–303
(5)
Data is the most valuable asset in space. It is produced by communicating and observing payloads, then downlinked to ground stations, and eventually delivered to the users, who generate information and insights from it. This paper explores an alternative avenue for the exploitation of space data, with the concept of Space Cloud. The space cloud is an orbiting cloud computing infrastructure providing in-orbit data storage and processing services. The idea is to enable on-orbit decision making including reactive planning and scheduling decisions, as well as complex resource management in space networks. The space cloud is the missing element to enable efficient and reliable intersatellite connectivity on top of which a whole new set of services and opportunities can be built in a similar fashion to what happened for the Internet during the 1990s. Building on previous work by the authors, this paper illustrates new efforts for the development of the space cloud concept through the demonstration of optical communication technology as a backbone for cloud computing in space. We illustrate how optical communications technology is an enabler of future space clouds.
-
Back Matter
- + Show details - Hide details
-
p.
(1)