Authors: Juan A. Vásquez-Peralvo, Jorge Querol, Flor Ortíz, Jorge Luis González Ríos, Eva Lagunas, Luis Manuel Garcés-Socarrás, Juan Carlos Merlano Duncán, Marcele O. K. Mendonça, Symeon Chatzinotas
Venue: IEEE Open Journal of the Communications Society (2024)
Research Areas: Satellite Communications, Beamforming & MIMO
DOI: 10.1109/ojcoms.2024.3385021
Open Access Repository: ORBiLu – University of Luxembourg

Optimal Linear Precoding Under Realistic Satellite Communications Scenarios

Mon, 01 Jan 2024 00:00:00 +0000

Abstract & Overview

Publication Metadata

Authors: Geoffrey Eappen, Jorge Luis Gonzalez, Vibhum Singh, Rakesh Palisetty, Alireza Haqiqtnejad, Liz Martinez Marrero, Jevgenij Krivochiza, Jorge Querol, Nicola Maturo, Juan Carlos Merlano Duncan, Eva Lagunas, Stefano Andrenacci, Symeon Chatzinotas
Venue: arXiv preprint arXiv:2408.08621 (2024)
Research Areas: Satellite Communications, Beamforming & MIMO
DOI: 10.1109/ojvt.2024.3509646
Open Access Repository: ORBiLu – University of Luxembourg

Performance Evaluation of Neuromorphic Hardware for Onboard Satellite Communication Applications

Mon, 01 Jan 2024 00:00:00 +0000

Abstract & Overview

Spiking neural networks (SNNs) implemented on neuromorphic processors (NPs) can enhance the energy efficiency of deployments of artificial intelligence (AI) for specific workloads. As such, NPs represent an interesting opportunity for implementing AI tasks power-limited onboard satellite communication spacecraft. In this article, we disseminate the findings of a recently completed study which targeted the comparison, in terms of performance and power-consumption, of different satellite communication use cases implemented on standard AI accelerators and on NPs. In particular, the article describes three prominent use cases, namely payload resource optimization, onboard interference detection and classification, and dynamic receive beamforming; and compares the performance of conventional convolutional neural networks (CNNs) implemented on Xilinx’s VCK5000 Versal development card, and SNNs on Intel’s neuromorphic chip Loihi 2.

Publication Metadata

Authors: Eva Lagunas, Flor Ortiz, Geoffrey Eappen, Saed Daoud, Wallace Alves Martins, Jorge Querol, Symeon Chatzinotas, Nicolas Skatchkovsky, Bipin Rajendran, Osvaldo Simeone
Venue: arXiv preprint arXiv:2401.06911 (2024)
Research Areas: Satellite Communications, AI & Neuromorphic SatCom, SDR & Experimental Testbeds
DOI: 10.1109/mwc.016.2300560
Open Access Repository: ORBiLu – University of Luxembourg

Rate-Splitting Multiple Access for Secure Communications Over CR MISO SWIPT Systems With Non-Linear EH Users

Mon, 01 Jan 2024 00:00:00 +0000

Abstract & Overview

In this paper, we investigate a secure transmission for a rate-splitting multiple-access (RSMA)-based multiple-input single-output (MISO) underlay cognitive radio (CR) system. The proposed network is composed of a set of secondary users (SUs) that utilize simultaneous wireless information and power transfer (SWIPT) technology and an additional set of non-linear energy harvesting (EH) users. Moreover, the system model under consideration is exposed to multiple eavesdroppers. Thus, we propose to minimize the transmit power intended to the SUs and EH users while maximizing the artificial noise (AN) generated by the secondary transmitter, aiming to counter eavesdroppers’ wiretaps while satisfying the quality-of-service constraints. Therefore, we develop a novel approach based on ant colony regression (ACOR) and semidefinite relaxation (SDR) methods to solve the challenging and non-convex problem which is further transformed into a bilevel optimization problem. Afterward, we investigate a comparative solution based on the particle swarm optimization (PSO) algorithm, the successive convex approximation (SCA) technique, and analyze the incidence of linear and non-linear EH designs. In addition, we compare the RSMA-based scheme with non-orthogonal multiple-access (NOMA), space-division multiple access (SDMA), and zero-forcing (ZF) techniques. Satisfactorily, simulation results prove the proposed ACOR-SDR framework achieves better performance and lower complexity than its counterparts.

Publication Metadata

Authors: Carla E. García, Mario R. Camana, Jorge Querol, Symeon Chatzinotas
Venue: IEEE Transactions on Green Communications and Networking (2024)
Research Areas: Satellite Communications, Signal Processing
DOI: 10.1109/tgcn.2024.3404891
Open Access Repository: ORBiLu – University of Luxembourg

Supervised Learning Based Real-Time Adaptive Beamforming On-Board Multibeam Satellites

Mon, 01 Jan 2024 00:00:00 +0000

Abstract & Overview

Satellite communications (SatCom) are crucial for global connectivity, especially in the era of emerging technologies like 6G and narrowing the digital divide. Traditional SatCom systems struggle with efficient resource management due to static multibeam configurations, hindering quality of service (QoS) amidst dynamic traffic demands. This paper introduces an innovative solution - real-time adaptive beamforming on multibeam satellites with software-defined payloads in geostationary orbit (GEO). Utilizing a Direct Radiating Array (DRA) with circular polarization in the 17.7 - 20.2 GHz band, the paper outlines DRA design and a supervised learning-based algorithm for on-board beamforming. This adaptive approach not only meets precise beam projection needs but also dynamically adjusts beamwidth, minimizes sidelobe levels (SLL), and optimizes effective isotropic radiated power (EIRP).

Publication Metadata

Authors: Flor Ortiz, Juan A Vasquez-Peralvo, Jorge Querol, Eva Lagunas, Jorge L González Rios, Marcele OK Mendonça, Luis Garces, Victor Monzon Baeza, Symeon Chatzinotas
Venue: 2024 18th European Conference on Antennas and Propagation (EuCAP) (2024)
Research Areas: Satellite Communications, Beamforming & MIMO
DOI: 10.23919/eucap60739.2024.10501412

5G NTN LEO based demonstrator using OpenAirInterface5G

Sun, 01 Jan 2023 00:00:00 +0000

Abstract & Overview

3GPP Release-17 formally recognizes Non- Terrestrial Network (NTN) components as an integral part of future telecommunication networks. The integration of 5G with NTN has gained significant traction due to the joint effort from academia, industry, and government space agencies. The first phase of 5G-NTN prototype development has been successful using GEO satellites. Moving ahead, LEO satellites can provide higher data rates and lower latency compared to GEO. In this paper, we discuss the 3GPP Release-17 compliant cross-layered adaptations done in OpenAirInterface5G during the project 5G-LEO (OpenAirInterface5G Extension for 5G Satellite Links). 5G-LEO aims to provide direct access to 5G services to a ground UE via a transparent payload LEO satellite. To the best of our knowledge, 5G-LEO is the first work involving the adaptation of 5G protocol addressing the challenges presented by the LEO satellite channel for example high and time-varying Doppler, Round-Trip-Time; and frequent handover. A Software Defined Radio-based end-to-end demonstrator has been developed during the project. Results from the experiments conducted during functional validation over the demonstrator are presented in this work. Our initial experiments show promising results and the feasibility of direct access to 5G services through transparent payload LEO satellites.

Publication Metadata

Authors: Sumit Kumar, Chandan Kumar Sheemar, Jorge Querol, Turker Yilmaz, Symeon Chatzinotas, Marwan Hammouda, Thomas Heyn, Thomas Schlichter, Paulo Marques, Luis Pereira
Venue: ICSSC (2023)
Research Areas: 6G-NTN, Satellite Communications, AI & Neuromorphic SatCom, SDR & Experimental Testbeds
DOI: 10.1049/icp.2024.0822
Open Access Repository: ORBiLu – University of Luxembourg

Beam centric Doppler pre-compensation for LEO-based 5G-NTN

Sun, 01 Jan 2023 00:00:00 +0000

Abstract & Overview

Integration of Non-Terrestrial Networks (NTN) components with 5G Terrestrial Networks (TN) is getting sig- nificant traction from academia and industry, resulting in the standardization of 5G-NTN in 3GPP. Low Earth Orbit (LEO) based 5G-NTN, especially regenerative payload, are of particular interest as they can provide latency and throughput comparable to terrestrial 5G networks. Initial synchronization is the first step when a User Equipment (UE) attempts to establish a data link with the gNB. However, the excessive Doppler caused by the LEO satellite’s fast movement must be exclusively compensated before the UE can successfully align time and frequency. This work presents an effective method to address this issue. In this method, a regenerative LEO satellite-based 5G gNodeB (gNB) pre-compensates the Doppler with respect to its Beam Center (BC) before any transmission. Further, a UE post-compensates the residual Doppler to achieve successful initial synchronization. With the proposed methodology, we expect the accuracy of initial synchronization to be comparable to 5G-TN without increasing the processing complexity at the UE. Furthermore, for the realistic scenario, our analysis includes the effect of the LEO satellite trajectory error sphere and pointing error.

Publication Metadata

Authors: Ashish Kumar Meshram, Sumit Kumar, Jorge Querol, Symeon Chatzinotas
Venue: IET Digital Library (2023)
Research Areas: 6G-NTN, Satellite Communications, GNSS & Positioning, Beamforming & MIMO
DOI: 10.1049/icp.2024.0815
Open Access Repository: ORBiLu – University of Luxembourg

Doppler effect mitigation in LEO-based 5G non-terrestrial networks

Sun, 01 Jan 2023 00:00:00 +0000

Abstract & Overview

In recent years, integrating Non-Terrestrial Networks (NTN) components with 5G Terrestrial Networks (TN) has led to considerable attention from academia and industry, leading to the standardization of 5G-NTN in 3GPP. Among the various NTN solutions, a notable one is the Low Earth Orbit (LEO)-based 5G-NTN with a regenerative payload. This system stands out because it can provide latency and throughput levels similar to terrestrial 5G networks. However, a significant challenge in this integration arises from the substantial Doppler effect caused by the rapid movement of LEO satellites. This effect must be effectively addressed to establish a successful data link between the User Equipment (UE) and the gNodeB (gNB). This study proposes a simple yet efficient method to tackle this issue. The method involves using a regenerative LEO satellite-based 5G gNB, which pre-compensates the Doppler frequency with respect to its beam center before initiating any data transmission. Subsequently, the UE performs post-compensation to handle residual Doppler frequency and achieve accurate initial synchronization. We evaluated the performance through simulations and demonstrated the effectiveness of the proposed system. The results indicate successful mitigation of Doppler effects, facilitating seamless communication between LEO satellite-based 5G NTN.

Publication Metadata

Authors: Ashish Kumar Meshram, Sumit Kumar, Jorge Querol, Symeon Chatzinotas
Venue: 2023 IEEE Globecom Workshops (GC Wkshps) (2023)
Research Areas: 6G-NTN, Satellite Communications, RFI Mitigation & GNSS Security, GNSS & Positioning
DOI: 10.1109/gcwkshps58843.2023.10464931
Open Access Repository: ORBiLu – University of Luxembourg

End-to-end performance evaluation of slp waveforms

Sun, 01 Jan 2023 00:00:00 +0000

Abstract & Overview

In this paper, we investigate the demodulation and decoding of the symbol-level precoded (SLP) signal using the conventional logarithmic likelihood ratio (LLR) and low-density parity check (LDPC) decoding algorithms operating in real-time on the software-defined radio (SDR) receiver. Its conventional forward error correction (FEC) is designed assuming symmetric additive white Gaussian noise (AWGN). While SLP generates asymmetric constellation point clouds it is unclear if it can achieve similar FEC gains in an end-to-end coded setup. The receiver is implemented based on the DVB-S2X standard. It estimates multi-beam interference-limited channel coefficients by using the orthogonal pilots embedded into the DVB-S2X frames to facilitate precoding at the transmitter. After the received frames are fully synchronized the payload symbols are decoded in two stages: soft decision using the LLR and hard decision using the LDPC decoders. We benchmark the bit error rate (BER) and frame error rate (FER) of the complete decoding chain while using the zero-forcing (ZF) and the selected SLP channel-interference canceling techniques. The conducted in-lab experiments show that the SLP can improve BER and FER performance in the conventional receiving and decoding design for symmetric constellations while achieving its original optimization goals.

Publication Metadata

Authors: Jevgenij Krivochiza, Juan Carlos Merlano Duncán, Jorge Querol, Symeon Chatzinotas
Venue: IEEE Access (2023)
Research Areas: Satellite Communications, Signal Processing
DOI: 10.1109/access.2023.3327643
Open Access Repository: ORBiLu – University of Luxembourg

Flexible beamforming for direct radiating arrays in satellite communications

Sun, 01 Jan 2023 00:00:00 +0000

Abstract & Overview

Onboard satellite communication systems generate and manage coverage beams over the Earth. Depending on data traffic requirements, the number of beams, side lobe levels, nulls, and EIRP, their beamwidth must be efficiently generated and managed. Therefore, this paper describes an approach for beam pattern synthesis applied to geostationary satellite communication systems. The beam pattern synthesis can generate beams with a beamwidth variation from 0.45° to 1.5°, which can be controlled independently for the two principal cuts. In addition, other requirements have been considered, e.g., latitude, and longitude, required EIRP, minimum and maximum side love levels for the two principal cuts, and nulling direction. The output of the synthesizer is a weight matrix with beamforming coefficients of the required beam. The direct radiating array in this contribution utilizes an open-ended waveguide antenna as unit cell elements with a period of 0.875λ0designed to work in left-hand circular polarization in the frequency band from 17.7 to 20.1 GHz. Since this design is intended for high-data rates applications, the minimum beamwidth requirements are very narrow. Therefore, 36 × 36 sub-arrays of 4 × 4 unit cells with a period of 3.5λ are considered to accomplish the beamwidth requirements while maintaining reduced computational and time resources for the weight matrix calculation compared to the conventional counterpart of 144×144 unit cells. The results show that the algorithm, which uses the surrogate optimizer, can compute the weight matrix and synthesize the beam with a slight deviation from the input data.

Publication Metadata

Authors: Juan Andrés Vásquez-Peralvo, Jorge Querol, Flor Ortíz, Jorge Luis González Rios, Eva Lagunas, Victor Monzon Baeza, Gianluca Fontanesi, Luis Manuel Garcés-Socorrás, Juan Carlos Merlano Duncan, Symeon Chatzinotas
Venue: IEEE Access (2023)
Research Areas: Satellite Communications, Beamforming & MIMO
DOI: 10.1109/access.2023.3300039
Open Access Repository: ORBiLu – University of Luxembourg

Flexible Payload Configuration for Satellites using Machine Learning

Sun, 01 Jan 2023 00:00:00 +0000

Abstract & Overview

Publication Metadata

Authors: Marcele OLIVEIRA KUHFUSS DE MENDONÇA, Flor de Guadalupe ORTIZ GOMEZ, Jorge Querol, Eva Lagunas, Juan Andres VASQUEZ-PERALVO, Victor MONZON BAEZA, Symeon Chatzinotas, Björn OTTERSTEN
Venue: IEEE International Conference on Machine Learning for Communication (2023)
Research Areas: Satellite Communications, AI & Neuromorphic SatCom
DOI: 10.1109/icmlcn59089.2024.10624839
Open Access Repository: ORBiLu – University of Luxembourg

Genetic Algorithm-based Beamforming in Subarray Architectures for GEO Satellites

Sun, 01 Jan 2023 00:00:00 +0000

Abstract & Overview

Publication Metadata

Authors: Juan Andrés Vásquez-Peralvo, Jorge Querol, Eva Lagunas, Flor Ortiz, Luis Manuel Garcés-Socarrás, Jorge Luis González-Rios, Victor Monzon Baeza, Symeon Chatzinotas
Venue: arXiv e-prints (2023)
Research Areas: Satellite Communications, Beamforming & MIMO
DOI: 10.48550/arxiv.2311.01366

Implementation of Edge-driven Geofencing and BVLOS Control for 5G-enabled Delivery Drone

Sun, 01 Jan 2023 00:00:00 +0000

Abstract & Overview

Drone-assisted applications have gained significant attention in both academic and industrial research and development. The utilization of advanced technologies like 5G and edge computing plays a vital role in facilitating the capabilities of these drone applications. Time-critical drone applications can be effectively supported by leveraging the high-bandwidth connectivity provided by 5G networks. Moreover, the integration of edge offloading addresses the challenge of limited onboard processing power in drone operations. This paper demonstrates the requirements and implementation of drone, edge, and 5G technology use case scenarios. Specifically, we focus on implementing a dynamic geofencing algorithm and beyond visual line of sight (BVLOS) control for the delivery drone use case in a real system using 5G, exploiting the use of edge computing to extend the onboard processing power of the drone. Finally, the obtained results and accompanying videos provide concrete evidence of the applicability of edge-driven 5G-enabled drones in drone-assisted use-case scenarios.

Publication Metadata

Authors: Abhishek Bera, Youssouf Drif, Jorge Querol, Miguel Olivares-Mendez
Venue: 2023 IEEE Globecom Workshops (GC Wkshps) (2023)
Research Areas: 6G-NTN, Satellite Communications
DOI: 10.1109/gcwkshps58843.2023.10464731

Location dependent allocation of timers and buffers at layer-2 in LEO based 5G-NTN

Sun, 01 Jan 2023 00:00:00 +0000

Abstract & Overview

The integration of Terrestrial Networks (TN) and Non-Terrestrial Networks (NTN), primarily utilizing satellites, has gained significant attention due to the potential of NTN to provide widespread coverage. The unique physical layer properties of 5G-NR offer the possibility of direct access to 5G services through satellites. However, the substantial Round-Trip Delays (RTD) associated with NTNs necessitate a re-evaluation of the design of timers and buffers in the radio link control (RLC) and packet data convergence protocol (PDCP) layers. This is particularly crucial for regenerative payload satellites with limited computational resources that require optimal utilization of the available resources. This research aims to explore the integration of emerging NTNs with limited resources from a higher-layer perspective. We propose a novel and efficient method for designing the buffers and timers in the RLC and PDCP layers without the need for intensive computations. Since the optimal solution depends on the RTD, which might result to be different for users located at different spots of the satellite beam, a user location-dependent approach is adopted. This approach is particularly relevant for efficiently utilizing the available limited resources and avoiding unnecessary delays in the system. Through simulations, we demonstrate that the proposed methods significantly improve performance in terms of resource utilization and reducing delays.

Publication Metadata

Authors: Chandan Kumar Sheemar, Sumit Kumar, Jorge Querol, Symeon Chatzinotas
Venue: IET Conference Proceedings CP873 (2023)
Research Areas: 6G-NTN, Satellite Communications
DOI: 10.1049/icp.2024.0823
Open Access Repository: ORBiLu – University of Luxembourg

Onboard processing in satellite communications using ai accelerators

Sun, 01 Jan 2023 00:00:00 +0000

Abstract & Overview

Satellite communication (SatCom) systems operations centers currently require high human intervention, which leads to increased operational expenditure (OPEX) and implicit latency in human action that causes degradation in the quality of service (QoS). Consequently, new SatCom systems leverage artificial intelligence and machine learning (AI/ML) to provide higher levels of autonomy and control. Onboard processing for advanced AI/ML algorithms, especially deep learning algorithms, requires an improvement of several magnitudes in computing power compared to what is available with legacy, radiation-tolerant, space-grade processors in space vehicles today. The next generation of onboard AI/ML space processors will likely include a diverse landscape of heterogeneous systems. This manuscript identifies the key requirements for onboard AI/ML processing, defines a reference architecture, evaluates different use case scenarios, and assesses the hardware landscape for current and next-generation space AI processors.

Publication Metadata

Authors: Flor Ortíz, Víctor Monzón Baeza, Luis Manuel Garcés-Socarrás, Juan A. Vásquez-Peralvo, Jorge Luis González Ríos, Gianluca Fontanesi, Eva Lagunas, Jorge Querol, Symeon Chatzinotas
Venue: Aerospace (2023)
Research Areas: Satellite Communications, AI & Neuromorphic SatCom
DOI: 10.3390/aerospace10020101
Open Access Repository: ORBiLu – University of Luxembourg

Short-Packet Communication Assisted Reliable Control of UAV for Optimum Coverage Range

Sun, 01 Jan 2023 00:00:00 +0000

Abstract & Overview

The reliability of command and control (C2) operation of the UAV is one of the crucial aspects for the success of UAV applications beyond 5G wireless networks. In this paper, we focus on the short-packet communication to maximize the coverage range of reliable UAV control. We quantify the reliability performance of the C2 transmission from a multi-antenna ground control station (GCS), which also leverages maximal-ratio transmission beamforming, by deriving the closed-form expression for the average block error rate (BLER). To obtain additional insights, we also derive the asymptotic expression of the average BLER in the high-transmit power regime and subsequently analyze the possible UAV configuration space to find the optimum altitude. Based on the derived average BLER, we formulate a joint optimization problem to maximize the range up to which a UAV can be reliably controlled from a GCS. The solution to this problem leads to the optimal resource allocation parameters including blocklength and transmit power while exploiting the vertical degrees of freedom for UAV placement. Finally, we present numerical and simulation results to corroborate the analysis and to provide various useful design insights.

Publication Metadata

Authors: Sourabh Solanki, Vibhum Singh, Sumit Gautam, Jorge Querol, Symeon Chatzinotas
Venue: ICC 2023-IEEE International Conference on Communications (2023)
Research Areas: Satellite Communications, Signal Processing
DOI: 10.1109/icc45041.2023.10279207
Open Access Repository: ORBiLu – University of Luxembourg

Single-and multi-connectivity for multi-satellite 6G communication networks

Sun, 01 Jan 2023 00:00:00 +0000

Abstract & Overview

This study explores the connectivity strategies for downlink multi-satellites in 6G communication networks. We begin with concepts, technologies, and trade-offs of Single-Connectivity (SC) and Multi-Connectivity (MC). Within the realm of MC, we present three different scenarios, one of which serves as a case study with a particular emphasis on Dual Connectivity (DC). This DC is performed between Geostationary Earth Orbit (GEO) and Low Earth Orbit (LEO) satellites for public safety systems. To improve reliability, we consider packet duplication mechanisms in addition to multi-band satellite capabilities. This supports the LEO link, addresses its limited availability, and facilitates a smooth handover between LEO satellites. Using link-level simulation, outage probability is examined by comparing the SC and MC modes under normal and adverse weather conditions. The findings of this study pave the way for more research to enhance connectivity solutions for more reliable and efficient global communication networks by bringing to light the MC opportunities for multi-satellite systems.

Publication Metadata

Authors: Mohammed Al-Ansi, Jorge Querol, Eva Lagunas, Symeon Chatzinotas
Venue: IET Digital Library (2023)
Research Areas: 6G-NTN, Satellite Communications
DOI: 10.1049/icp.2024.0840

System Analysis of Lunar Computations Communication Architectures

Sun, 01 Jan 2023 00:00:00 +0000

Abstract & Overview

This research contribution by Laura Chikosman, Miguel Angel OLIVARES MENDEZ, Juan Carlos MERLANO DUNCAN, Sumit Kumar et al. (2023), published in Space Resources Week, investigates “System Analysis of Lunar Computations Communication Architectures” within the domains of Satellite Communications, Signal Processing. The work is part of Dr. Jorge Querol’s research portfolio in advanced satellite communications, non-terrestrial networks (NTN), and radio-frequency signal processing at SnT (University of Luxembourg) and UPC-BarcelonaTech.

Publication Metadata

Authors: Laura Chikosman, Miguel Angel OLIVARES MENDEZ, Juan Carlos MERLANO DUNCAN, Sumit Kumar, Chandan Kumar SHEEMAR, Symeon Chatzinotas, Loveneesh Rana, Andreas Hein, Youssouf Drif, Swetha Varadarajulu, Jorge Querol
Venue: Space Resources Week (2023)
Research Areas: Satellite Communications, Signal Processing

5G-NTN GEO-based in-lab demonstrator using OpenAirInterface5G

Sat, 01 Jan 2022 00:00:00 +0000

Abstract & Overview

This research contribution by Sumit Kumar, Abdelrahman Abdalla, Oltjon Kodheli, Jorge Querol et al. (2022), published in 11th Advanced Satellite Multimedia Conference, investigates “5G-NTN GEO-based in-lab demonstrator using OpenAirInterface5G” within the domains of 6G-NTN, Satellite Communications, AI & Neuromorphic SatCom. The work is part of Dr. Jorge Querol’s research portfolio in advanced satellite communications, non-terrestrial networks (NTN), and radio-frequency signal processing at SnT (University of Luxembourg) and UPC-BarcelonaTech.

Publication Metadata

Authors: Sumit Kumar, Abdelrahman Abdalla, Oltjon Kodheli, Jorge Querol, Symeon Chatzinotas, Thomas Schlichter, Guido Casati, Thomas Heyn, Florian Volk, Sertac Kaya
Venue: 11th Advanced Satellite Multimedia Conference (2022)
Research Areas: 6G-NTN, Satellite Communications, AI & Neuromorphic SatCom, SDR & Experimental Testbeds

Architectures and synchronization techniques for distributed satellite systems: A survey

Sat, 01 Jan 2022 00:00:00 +0000

Abstract & Overview

Cohesive Distributed Satellite Systems (CDSSs) is a key enabling technology for the future of remote sensing and communication missions. However, they have to meet strict synchronization requirements before their use is generalized. When clock or local oscillator signals are generated locally at each of the distributed nodes, achieving exact synchronization in absolute phase, frequency, and time is a complex problem. In addition, satellite systems have significant resource constraints, especially for small satellites, which are envisioned to be part of the future CDSSs. Thus, the development of precise, robust, and resource-efficient synchronization techniques is essential for the advancement of future CDSSs. In this context, this survey aims to summarize and categorize the most relevant results on synchronization techniques for Distributed Satellite Systems (DSSs). First, some important architecture and system concepts are defined. Then, the synchronization methods reported in the literature are reviewed and categorized. This article also provides an extensive list of applications and examples of synchronization techniques for DSSs in addition to the most significant advances in other operations closely related to synchronization, such as inter-satellite ranging and relative position. The survey also provides a discussion on emerging data-driven synchronization techniques based on Machine Learning (ML). Finally, a compilation of current research activities and potential research topics is proposed, identifying problems and open challenges that can be useful for researchers in the field.

Publication Metadata

Authors: Liz Martínez Marrero, Juan Carlos Merlano Duncán, Jorge Querol, Sumit Kumar, Jevgenij Krivochiza, Shree Krishna Sharma, Symeon Chatzinotas, Adriano Camps, Björn Ottersten
Venue: IEEE access (2022)
Research Areas: Satellite Communications
DOI: 10.1109/access.2022.3169499

Differential phase compensation in over-the-air precoding test-bed for a multi-beam satellite

Sat, 01 Jan 2022 00:00:00 +0000

Abstract & Overview

This article presents a closed-loop differential phase compensation system for a precoding-enabled multibeam satellite forward link and its validation by live experiments on a GEO satellite scenario. The precoding operation avoids inter-beam interference and maximizes the spectrum efficiency by full frequency reuse as an alternative to the traditional two-color or four-color reuse methods proposed in the DVB-S2 standard. However, the satellite payload introduces differential phase and frequency impairments, which can degrade the precoding performance. This work describes the implementation of the differential phase and frequency tracking and compensation loop in an end-to-end testbed over a multibeam satellite system with independent local oscillators. The developed system performs end-to-end real-time communication over the satellite link, including channel measurements and precompensation. Results are validated by an over-the-air demonstration using two beams of the SES-14 multibeam satellite. Each beam is transmitted by independent transponders, which results in differential frequency and phase offsets due to the transponder undisciplined local oscillators. This phase offset makes it impossible to use precoding without the phase compensation loop. We prove that the implemented system can successfully track and compensate the differential phase and frequency to improve precoding performance.

Publication Metadata

Authors: Liz Martínez Marrero, Juan Carlos Merlano Duncán, Jorge Querol, Nicola Maturo, Jevgenij Krivochiza, Symeon Chatzinotas, Björn Ottersten
Venue: 2022 IEEE Wireless Communications and Networking Conference (WCNC) (2022)
Research Areas: Satellite Communications, AI & Neuromorphic SatCom, Beamforming & MIMO
DOI: 10.1109/wcnc51071.2022.9771918
Open Access Repository: ORBiLu – University of Luxembourg

Machine learning for radio resource management in multibeam GEO satellite systems

Sat, 01 Jan 2022 00:00:00 +0000

Abstract & Overview

Satellite communications (SatComs) systems are facing a massive increase in traffic demand. However, this increase is not uniform across the service area due to the uneven distribution of users and changes in traffic demand diurnal. This problem is addressed by using flexible payload architectures, which allow payload resources to be flexibly allocated to meet the traffic demand of each beam. While optimization-based radio resource management (RRM) has shown significant performance gains, its intense computational complexity limits its practical implementation in real systems. In this paper, we discuss the architecture, implementation and applications of Machine Learning (ML) for resource management in multibeam GEO satellite systems. We mainly focus on two systems, one with power, bandwidth, and/or beamwidth flexibility, and the second with time flexibility, i.e., beam hopping. We analyze and compare different ML techniques that have been proposed for these architectures, emphasizing the use of Supervised Learning (SL) and Reinforcement Learning (RL). To this end, we define whether training should be conducted online or offline based on the characteristics and requirements of each proposed ML technique and discuss the most appropriate system architecture and the advantages and disadvantages of each approach.

Publication Metadata

Authors: Flor Ortíz, Lei Lei, Eva Lagunas, Ramón Martínez Rodríguez‐Osorio, Daniele Tarchi, Jorge Querol, Miguel A. Salas‐Natera, Symeon Chatzinotas
Venue: Electronics (2022)
Research Areas: Satellite Communications, AI & Neuromorphic SatCom, Beamforming & MIMO
DOI: 10.3390/electronics11070992
Open Access Repository: ORBiLu – University of Luxembourg

Non-coherent massive MIMO integration in satellite communication

Sat, 01 Jan 2022 00:00:00 +0000

Abstract & Overview

Massive Multiple Input-Multiple Output (mMIMO) technique has been considered an efficient standard to improve the transmission rate significantly for the following wireless communication systems, such as 5G and beyond. However, implementing this technology has been facing a critical issue of acquiring much channel state information. Primarily, this problem becomes more criticising in the integrated satellite and terrestrial networks (3GPP-Release 15) due to the countable high transmission delay. To deal with this challenging problem, the mMIMO-empowered non-coherent technique can be a promising solution. To our best knowledge, this paper is the first work considering employing the non-coherent mMIMO in satellite communication systems. This work aims to analyse the challenges and opportunities emerging with this integration. Moreover, we identified the issues in this conjunction. The preliminary results presented in this work show that the performance measured in bit error rate (BER) and the number of antennas are not far from that required for terrestrial links. Furthermore, thanks to mMIMO in conjunction with the non-coherent approach, we can work in a low signal-to-noise ratio (SNR) regime, which is an excellent advantage for satellite links.

Publication Metadata

Authors: V.M. Baeza, V.N. Ha, Jorge Querol, S. Chatzinotas
Venue: 39th International Communications Satellite Systems Conference (ICSSC (2022)
Research Areas: Satellite Communications, Beamforming & MIMO
DOI: 10.48550/arxiv.2209.09701
Open Access Repository: ORBiLu – University of Luxembourg

Non-Coherent Massive MIMO Integration in Satellite Communication

Sat, 01 Jan 2022 00:00:00 +0000

Abstract & Overview

Publication Metadata

Authors: Víctor Monzón Baeza, Vu Nguyen Ha, Jorge Querol, Symeon Chatzinotas
Venue: arXiv preprint arXiv:2209.09701 (2022)
Research Areas: Satellite Communications, Beamforming & MIMO
DOI: 10.1049/icp.2023.1386

A cubesat-ready phase synchronization digital payload for coherent distributed remote sensing missions

Fri, 01 Jan 2021 00:00:00 +0000

Abstract & Overview

Distributed antenna arrays, fractionated payloads and cooperative platforms can provide unprecedented performance in the next generation of spaceborne communications and remote sensing systems. Remote phase synchronization of physically separated oscillators is the first step towards a coherent operation of distributed systems. This work shows the preliminary results of a TDD remote phase synchronization algorithm with a master-follower architecture. Herein, we describe the implementation and validation of the proposed algorithm. The implementation has been conducted in a Cubesat-ready software defined radio and validated at the end-to-end satellite communications testbed available at the University of Luxembourg.

Publication Metadata

Authors: Jorge Querol, J. C. Merlano-Duncan, L. Martinez-Marrero, J. Krivochiza, S. Kumar, N Maturo, A. Camps, S. Chatzinotas, B. Ottersten
Venue: 2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS (2021)
Research Areas: Satellite Communications, JCAS & Earth Observation
DOI: 10.1109/igarss47720.2021.9554042
Open Access Repository: ORBiLu – University of Luxembourg

Centralized gateway concept for precoded multi-beam GEO satellite networks

Fri, 01 Jan 2021 00:00:00 +0000

Abstract & Overview

Satellite Communications offer complementary benefits to terrestrial 5G/6G infrastructure, covering a wide range of use cases in need of ubiquitous coverage and reliability. However, to be as competitive as the terrestrial counterpart in terms of supplied throughput, satellite communications require a highly efficient use of the limited available spectrum. Linear precoding has demonstrated the ability to boost the spectral efficiency in the satellite domain, but raising a new issue: the bandwidth requirements of the feeder link. Deployment of several gateways, each of which precoding an independent cluster of beams causes performance degradation. Therefore, in this paper, we investigate the centralized gateway concept, where all digital baseband processes (including precoding) are implemented in a remote server connected via high speed fibers to the distributed remote gateways responsible for the downlink and uplink of the satellite radio frequency signals. In particular, we highlight the main technical challenges and provide a preliminary vision of potential solutions.

Publication Metadata

Authors: Steven Kisseleff, Eva Lagunas, Jevgenij Krivochiza, Jorge Querol, Nicola Maturo, Liz Martínez Marrero, Juan Carlos Merlano Duncán, Symeon Chatzinotas
Venue: 2021 IEEE 94th Vehicular Technology Conference (VTC2021-Fall) (2021)
Research Areas: Satellite Communications, Beamforming & MIMO
DOI: 10.1109/vtc2021-fall52928.2021.9625524
Open Access Repository: ORBiLu – University of Luxembourg

End-to-end precoding validation over a live GEO satellite forward link

Fri, 01 Jan 2021 00:00:00 +0000

Abstract & Overview

In this paper we demonstrate end-to-end precoded multi-user multiple-input single-output (MU-MISO) communications over a live GEO satellite link. Precoded communications enable full frequency reuse (FFR) schemes in satellite communications (SATCOM) to achieve broader service availability and higher spectrum efficiency than with the conventional four-color (4CR) and two-color (2CR) reuse approaches. In this scope, we develop an over-the-air test-bed for end-to-end precoding validations. We use an actual multi-beam satellite to transmit and receive precoded signals using the DVB-S2X standard based gateway and user terminals. The developed system is capable of end-to-end real-time communications over the satellite link including channel measurements and precompensation. It is shown, that by successfully canceling inter-user interference in the actual satellite FFR link precoding brings gains in terms of enhanced SINR and increased system goodput.

Publication Metadata

Authors: Jevgenij Krivochiza, Juan Carlos Merlano Duncan, Jorge Querol, Nicola Maturo, Liz Martinez Marrero, Stefano Andrenacci, Jens Krause, Symeon Chatzinotas
Venue: IEEE Access (2021)
Research Areas: Satellite Communications, Beamforming & MIMO
DOI: 10.48550/arxiv.2103.11760

Wireless and networking technologies for social distancing-indoor and outdoor

Fri, 01 Jan 2021 00:00:00 +0000

Abstract & Overview

This chapter reviews the suitability of the most relevant wireless and networking communications technologies (e.g. GNSS, cellular, WiFi, Bluetooth and RFID) for the implementation of social distancing applications such as interpersonal distancing, real-time area monitoring, or geo-fencing.

Publication Metadata

Authors: Jorge Querol, Alejandro González, Vu Nguyen Ha, Sumit Kumar, Symeon Chatzinotas
Venue: Institution of Engineering and Technology eBooks (2021)
Research Areas: Satellite Communications, Signal Processing
DOI: 10.1049/pbte104e_ch3

Satellite communications in the new space era: A survey and future challenges

Wed, 01 Jan 2020 00:00:00 +0000

Abstract & Overview

Satellite communications (SatComs) have recently entered a period of renewed interest motivated by technological advances and nurtured through private investment and ventures. The present survey aims at capturing the state of the art in SatComs, while highlighting the most promising open research topics. Firstly, the main innovation drivers are motivated, such as new constellation types, on-board processing capabilities, non-terrestrial networks and space-based data collection/processing. Secondly, the most promising applications are described, i.e., 5G integration, space communications, Earth observation, aeronautical and maritime tracking and communication. Subsequently, an in-depth literature review is provided across five axes: i) system aspects, ii) air interface, iii) medium access, iv) networking, v) testbeds & prototyping. Finally, a number of future challenges and the respective open research topics are described.

Publication Metadata

Authors: Oltjon Kodheli, Eva Lagunas, Nicola Maturo, Shree Krishna Sharma, Bhavani Shankar, Jesus Fabian Mendoza Montoya, Juan Carlos Merlano Duncan, Danilo Spano, Symeon Chatzinotas, Steven Kisseleff, Jorge Querol
Venue: IEEE Communications Surveys & Tutorials (2020)
Research Areas: Satellite Communications
DOI: 10.1109/comst.2020.3028247
Open Access Repository: ORBiLu – University of Luxembourg

System modeling and design aspects of next generation high throughput satellites

Wed, 01 Jan 2020 00:00:00 +0000

Abstract & Overview

As compared to terrestrial systems, the design of Satellite Communication (SatCom) systems requires a different approach due to differences in terms of wave propagation, operating frequency, antenna structures, interfering sources, limitations of onboard processing, power limitations and transceiver impairments. In this regard, this letter aims to identify and discuss important modeling and design aspects of the next generation High Throughput Satellite (HTS) systems. First, communication models of HTSs including the ones for multibeam and multicarrier satellites, multiple antenna techniques, and for SatCom payloads and antennas are highlighted and discussed. Subsequently, various design aspects of SatCom transceivers including impairments related to the transceiver, payload and channel, and traffic-based coverage adaptation are presented. Finally, some open topics are identified and discussed.

Publication Metadata

Authors: Shree Krishna Sharma, Jorge Querol Borras, Nicola Maturo, Symeon Chatzinotas, Bjorn Ottersten
Venue: IEEE Communications Letters (2020)
Research Areas: Satellite Communications
DOI: 10.1109/lcomm.2020.3036593

System Modelling and Design Aspects of Next Generation High Throughput Satellites

Wed, 01 Jan 2020 00:00:00 +0000

Abstract & Overview

Publication Metadata

Authors: Shree Krishna Sharma, Jorge Querol, Nicola Maturo, Symeon Chatzinotas, Björn Ottersten
Venue: arXiv e-prints (2020)
Research Areas: Satellite Communications
DOI: 10.48550/arXiv.2011.09333

Demonstrator of precoding technique for a multi-beams satellite system

Tue, 01 Jan 2019 00:00:00 +0000

Abstract & Overview

In this document, we present a real-time demonstrator of precoding technique, to be used to enable full frequency reuse in the forward link of future multi-beam satellite systems. To this aim, our demonstrator will implement all the functionalities required to correctly exploit the achievable gain coming from the usage of precoding. In particular, the main functionality to be included on the User Terminal (UT) side is the proper collection of the estimated Channel State Information (CSI). On the Gateway (GW), a computationally-efficient calculation of the precoding matrix and application of the resulting precoder to the vectors of symbol streams, have to been developed. Using this demonstrator we are able to prove the feasibility of precoding implementation in satellite communications relying on the superframe framing structure defined in Annex E of the DVB-S2X standard.

Publication Metadata

Authors: Nicola Maturo, Juan Carlos Merlano Duncan, Jevgenij Krivochiza, Jorge Querol, Danilo Spano, Symeon Chatzinotas, Björn Ottersten
Venue: 2019 8th International Workshop on Tracking, Telemetry and Command (2019)
Research Areas: Satellite Communications, Beamforming & MIMO, SDR & Experimental Testbeds
DOI: 10.1109/ttc.2019.8895466
Open Access Repository: ORBiLu – University of Luxembourg

The global navigation satellite systems reflectometry (GNSS-R) microwave interferometric reflectometer: Hardware, calibration, and validation experiments

Tue, 01 Jan 2019 00:00:00 +0000

Abstract & Overview

This manuscript describes the Microwave Interferometric Reflectometer (MIR) instrument, a multi-beam dual-band GNSS-Reflectometer with beam-steering capabilities built to assess the performance of a PAssive Reflectrometry and Interferometry System-In Orbit Demonstrator (PARIS-IoD) like instrument and to compare the performance of different GNSS-R techniques and signals. The instrument is capable of tracking up to 4 different GNSS satellites, two at L1/E1 band, and two at L5/E5 band. The calibration procedure of the up- and down-looking arrays is presented, the calibration performance is evaluated, and the results of the validation experiments carried out before the field experiments are shown in this paper.

Publication Metadata

Authors: Raul Onrubia, Daniel Pascual, Jorge Querol, Hyuk Park, Adriano Camps
Venue: Sensors (2019)
Research Areas: Satellite Communications, JCAS & Earth Observation, GNSS & Positioning, SDR & Experimental Testbeds
DOI: 10.3390/s19051019

3CAT-3/MOTS, an experimental nanosatellite for multispectral and GNSS-R earth observation: airborne optical and GNSS-R campaign

Mon, 01 Jan 2018 00:00:00 +0000

Abstract & Overview

The3Cat-3/MOTS mission is a joint initiative between the Institut Cartogràfic i Geològic de Catalunya (ICGC) and the Universitat Politècnica de Catalunya-BarcelonaTech (UPC) to foster new and innovative technologies on Earth Observation (EO) based on the data fusion of Global Navigation Satellite Systems Reflectometry (GNSS-R) and optical payloads on a 6U CubeSat platform. The final objective of the mission is to provide soil moisture mapping through the GNSS-R payload and improve its resolution by data fusion with the multi-spectral optical data acquired. This technique has been successfully applied to SMOS, but never performed from a 6U CubeSat carrying both payloads. An airborne optical and GNSS-R field experiment has been carried out to test/develop the algorithm and to analyze the results both separately (GNSS-R + optical data) and as a soil moisture product, once performed the data fusion.

Publication Metadata

Authors: Jordi Castellvi-Esturi, Adriano Camps, Jordi Corbera, Raul Onrubia, Ramon Alamús, Daniel Pascual, Jorge Querol, Hyuk Park
Venue: IGARSS 2018-2018 IEEE International Geoscience and Remote Sensing Symposium (2018)
Research Areas: Satellite Communications, JCAS & Earth Observation, GNSS & Positioning, AI & Neuromorphic SatCom, SDR & Experimental Testbeds
DOI: 10.1109/igarss.2018.8518216

Altimetric performance of the GEROS experiment at the ISS

Fri, 01 Jan 2016 00:00:00 +0000

Abstract & Overview

The GNSS rEflectometry, Radio Occultation and Scatterometry onboard the International Space Station (GEROS-ISS) is an innovative experiment for climate research, proposed in 2011 within a call of the European Space Agency (ESA) for installation at the ISS. This international proposal was the only one selected for further studies by ESA out of ~25 submitted ones. In this work, an updated assessment of the instrument performance for the near-nadir altimetry (GNSS-R) mode and scatterometry is assessed, including the effect of the inter-modulation signals, and the expected degradation due to presence of radio-frequency interference coming from DME/TACAN systems. These results correspond to the study lead by Airbus Defence and Space-Spain, one of the two parallel Phase A studies conducted by ESA.

Publication Metadata

Authors: A. Camps, H. Park, R. Onrubia, D. Pascual, Jorge Querol, A. Alonso-Arroyo, J. Benito, A. Andres-Beivide, S. Moreno, X. Ballesteros, M. Segarra, R. Vilaseca, A. Rius, M. Martin-Neira
Venue: 2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) (2016)
Research Areas: Satellite Communications, Signal Processing
DOI: 10.1109/igarss.2016.7730468

Impact of multi-path by ISS structure on GEROS-ISS measured waveforms

Fri, 01 Jan 2016 00:00:00 +0000

Abstract & Overview

The GNSS rEflectometry, Radio Occultation and Scatterometry onboard the International Space Station (GEROS-ISS) experiment consists of the installation of a GNSS reflectometry (GNSS-R) instrument on the International Space Station (ISS). Due to the complex structure of ISS, the GEROS-ISS instrument suffers from multipath effects. The collected signals are not only from received directly, but also after multiple reflections in the ISS structure. This work analyzes the multipath effect of the GEROS-ISS instrument based on the ISS structure. Using the ray tracing simulation, all rays reaching the instrument after one or two reflections are computed, as well as the corresponding additional delays. This information, together with the direction of arrival to the antenna arrays (up and down-looking), and the co- and cross-polar antenna patterns is used to assess the impact of multipath on the waveforms are demonstrated.

Publication Metadata

Authors: Hyuk Park, Adriano Camps, Ivan Sekulic, J. M. Rius, Daniel Pascual, Alberto Alonso-Arroyo, Jorge Querol, Raul Onrubia
Venue: 2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) (2016)
Research Areas: Satellite Communications, Signal Processing
DOI: 10.1109/igarss.2016.7730463

Improvement of PAU/PARIS end-to-end performance simulator (P 2 EPS): Land scattering including topography

Fri, 01 Jan 2016 00:00:00 +0000

Abstract & Overview

This work presents an improvement of the P2EPS end-to-end simulator to assess the performances of Global Navigation Satellite System Reflectometry (GNSS-R) space missions over land. Beyond the single specular reflection model, topography effects are included. In order to avoid the computational burden of facet approach based on the bi-static radar model, the Phong reflection model is employed. By calculating the delay, Doppler frequency, and relative intensity of scattered points, the topography effects can be accounted for as a sort of impulse response in the delay, and Doppler domains to be convolved with the Woodward Ambiguity function.

Publication Metadata

Authors: Hyuk Park, Adriano Camps, Daniel Pascual, Alberto Alonso-Arroyo, Jorge Querol, Raul Onrubia
Venue: 2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) (2016)
Research Areas: Satellite Communications, Signal Processing
DOI: 10.1109/igarss.2016.7730464

MCU Controlled DC-DC Buck/Boost Converter for Supercapacitors

Sun, 01 Jan 2012 00:00:00 +0000

Abstract & Overview

This work is focused on DC to DC conversion, what is a crucial function to enable the use of supercapacitors for energy storage. A theoretical study and comparison of methods, algorithms and techni …

Publication Metadata

Authors: Jorge Querol
Venue: Conference Paper (2012)
Research Areas: Satellite Communications, Signal Processing