SDR & Experimental Testbeds | Dr. Jorge Querol

Joint 5G NR-NTN and GNSS Overlay in MEO: Experimental Assessment of Navigation Data Robustness under DSSS–OFDM Coexistence

Wed, 07 Oct 2026 00:00:00 +0000

Abstract & Overview

Recent advances in Joint Communication and Positioning (JCAP) motivate the integration of navigation signals within communication waveforms. This paper investigates a hybrid Direct-Sequence Spread Spectrum (DSSS)–Orthogonal Frequency-Division Multiplexing (OFDM) waveform in which a low-power legacy Global Positioning System (GPS) L1 Coarse/Acquisition (C/A) signal carrying the Legacy Navigation Message (LNAV) message is intentionally overlaid on a Fifth Generation (5G) New Radio (NR) Non-Terrestrial Network (NTN) downlink. The focus is on the Global Navigation Satellite System (GNSS)-side ability to acquire, track, and demodulate the navigation message in the presence of structured 5G interference. The study considers a Medium Earth Orbit (MEO) scenario representative of the SES O3b mPOWER constellation at an altitude of approximately 8000 km. First, MEO Doppler dynamics are characterized using representative orbital parameters, and Monte Carlo (MC) simulations are performed to evaluate LNAV recovery versus Signal-to-Interference-plus-Noise Ratio (SINR) for different transmitted Signal-to-Interference Ratio (SIR) levels. Performance is assessed using navigation-centric metrics, including Bit Error Rate (BER), valid 6 s subframe decoding, valid decoding of the first three subframes, and complete 30 s LNAV frame recovery. The same 35 s reference composite waveform is then transmitted in a continuous loop through the SES O3b mPOWER transparent MEO relay. For each tested SIR level, 300 s of baseband In-phase and Quadrature (I/Q) samples are recorded and processed offline using a MATLAB-based GNSS receiver with 5G Synchronization Signal Block (SSB)-assisted frequency initialization. Simulation results show that, in the considered MEO scenario, Doppler dynamics are moderate and do not constitute the dominant limitation; performance is mainly governed by thermal noise and 5G interference. Experimental results demonstrate reliable LNAV recovery down to approximately -25 dB transmitted SIR, while end-to-end recovery becomes unreliable at -30 dB and below. Since the effective received SINR is not directly available, the experimental results are interpreted as practical transmitted-SIR thresholds.

Publication Metadata

Authors: Idir Edjekouane, Alejandro Gonzalez Garrido, Jevgenij Krivochiza, Jorge Querol, Symeon Chatzinotas
Venue: Proceedings of the Satellite Division’s International Technical Meeting (Online)/Proceedings of the Satellite Division’s International Technical Meeting (CD-ROM) (2026)
Research Areas: 6G-NTN, Satellite Communications, GNSS & Positioning, SDR & Experimental Testbeds
DOI: 10.33012/2026.20684

5G-NR Over Transparent Payload GEO Satellites: A Hands-On Approach Using OpenAirInterface5G-NTN

Wed, 01 Jan 2025 00:00:00 +0000

Abstract & Overview

The inclusion of Non-Terrestrial Network (NTN) components has significantly enhanced the reach of 5G networks. OpenAirInterface5G (OAI) has developed an open-source, Software-Defined Radio (SDR)-based framework for 5G-NTN, using its Terrestrial Network (TN) protocol stack as the baseline. OAI’s 5G-NTN adaptations are still evolving, requiring in-lab validations and field trials to assess its effectiveness in addressing the unique challenges of NTN components and channel characteristics. Live satellite tests, unlike simulations, demand manual tuning of key parameters like carrier frequency offset, timing offsets, and gain calibration. In this work, we present a practical approach for deploying 5G over GEO satellites using the OAI 5G-NTN suite, addressing (a) satellite channel impairments and (b) limitations in OAI’s current 5G-NTN implementation. Our work provides step-by-step calibrations, ensuring both experiment reproducibility and the realization of a full 5G-NTN link. We further identify the performance bottlenecks and experiment with (a) Radio Link Control Acknowledgment Mode (RLC-AM) parameters and (b) Low-Density Parity Check (LDPC) iterations to improve end-to-end throughput. We validate our methods via live tests over a transparent payload GEO satellite. We believe that our work represents a critical step in bridging the gap between lab-based 5G-NTN emulation and live satellite testing, offering valuable insights to advance 5G-NTN research and development.

Publication Metadata

Authors: Sumit Kumar, Jevgenij Krivochiza, Türker Yilmaz, Jorge Querol, Symeon Chatzinotas, Stefano Andrenacci, Joël Grotz
Venue: IEEE Open Journal of the Communications Society (2025)
Research Areas: 6G-NTN, Satellite Communications, AI & Neuromorphic SatCom, SDR & Experimental Testbeds
DOI: 10.1109/ojcoms.2025.3586871
Open Access Repository: ORBiLu – University of Luxembourg

Resource-Efficient FPGA Architecture for Real-Time RFI Mitigation in Interferometric Radiometers

Sat, 14 Dec 2024 00:00:00 +0000

Abstract & Overview

Interferometric radiometers operating at L-band, such as ESA’s SMOS mission, enable crucial Earth observations providing high-resolution measurements of soil moisture, ocean salinity, and other geophysical parameters. However, the increasing electromagnetic spectrum utilization has led to significant Radio Frequency Interference (RFI) challenges, particularly critical given the sensors’ fine temperature resolution requirements of less than 1 K. This work presents the hardware implementation of an advanced RFI detection and mitigation algorithm specifically designed for interferometric radiometers, targeting future L-band missions. The implementation processes 1-bit quantized signals at 57.69375 MHz from multiple receivers, employing time-frequency analysis and polarimetric detection techniques while optimizing Field Programmable Gate Array (FPGA) resource utilization. Novel optimization strategies include overclocked processing cores operating at 230.775 MHz, efficient resource sharing through operation serialization, and strategic memory management. The system achieves real-time processing capabilities while maintaining detection probabilities above 63% with false alarm rates below 1% for typical interference scenarios. Performance validation using synthetic datasets demonstrates robust operation across various RFI conditions, making this implementation suitable as part of the RFI detection and mitigation efforts for future interferometric radiometer missions beyond SMOS.

Publication Metadata

Authors: Adrián Pérez-Portero, Jorge Querol, Adriano Camps
Venue: Sensors (2024)
Research Areas: JCAS & Earth Observation, RFI Mitigation & GNSS Security, SDR & Experimental Testbeds
DOI: 10.3390/s24248001
Open Access Repository: ORBiLu – University of Luxembourg

5G Non-Terrestrial Networks with OpenAirInterface: An Experimental Study over GEO Satellites

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

Abstract & Overview

The 3rd Generation Partnership Project (3GPP) aims to integrate non-terrestrial networks (NTNs) with terrestrial 5G networks. In this context, prototyping and testing are essential to demonstrate the readiness of new 5G-NTN releases. However, commercial 5G protocol stack implementations are usually costly and closed solutions, which makes it challenging for universities and nonprofit research institutions to adapt and customize them for 5G-NTN testing and development purposes. Software-defined radio testbeds that utilize open-source software implementations are an attractive alternative. In this article, we describe our protocol stack adaptation of an open-source implementation for 5G-NTN based on OpenAirInterface (OAI), which runs on commodity hardware. We evaluate the performance of our 5G-NTN in various layers in real-world environments with a transparent geostationary satellite. We validate our testbed with a variety of Internet applications. These include streaming video, web browsing, and voice over IP. The results indicate that the current implementation utilizing the 5 MHz bandwidth is reliable over several hours and achieves both downlink and uplink speeds of 3.6 Mb/s while maintaining a typical geostationary latency of approximately 530 ms. The tests demonstrate that our 5G-NTN testbed is an reliable alternative to costly commercial implementations.

Publication Metadata

Authors: Florian Völk, Thomas Schlichter, Sumit Kumar, Robert T. Schwarz, Andreas Knopp, Marwan Hammouda, Thomas Heyn, Jorge Querol, Symeon Chatzinotas, Adam Kapovits
Venue: IEEE Access (2024)
Research Areas: 6G-NTN, Satellite Communications, AI & Neuromorphic SatCom, SDR & Experimental Testbeds
DOI: 10.1109/access.2024.3483958
Open Access Repository: ORBiLu – University of Luxembourg

Artificial Intelligence Satellite Telecommunication Testbed using Commercial Off-The-Shelf Chipsets

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

Abstract & Overview

The Artificial Intelligence Satellite Telecommunications Testbed (AISTT), part of the ESA project SPAICE, is focused on the transformation of the satellite payload by using artificial intelligence (AI) and machine learning (ML) methodologies over available commercial off-the-shelf (COTS) AI-capable chips for onboard processing. The objectives include validating artificial intelligence-driven SATCOM scenarios such as interference detection, spectrum sharing, radio resource management, decoding, and beamforming. The study highlights hardware selection and payload architecture. Preliminary results show that ML models significantly improve signal quality, spectral efficiency, and throughput compared to conventional payload. Moreover, the testbed aims to evaluate the performance and the use of AI-capable COTS chips in onboard SATCOM contexts.

Publication Metadata

Authors: Luis Manuel GARCES SOCARRAS, Amirhossein Nik, Flor de Guadalupe ORTIZ GOMEZ, Juan Andres VASQUEZ-PERALVO, Jorge Luis GONZALEZ RIOS, Mouhamad CHEHAITLY, Marcele OLIVEIRA KUHFUSS DE MENDONÇA, Eva Lagunas, Jan Thoemel, Sumit Kumar, Jorge Querol
Venue: AI in and for Space (ESA SPAICE 2024) (2024)
Research Areas: Satellite Communications, SDR & Experimental Testbeds
DOI: 10.5281/zenodo.13885550
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

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

Experimental Study of the Effects of RLC Modes for 5G-NTN applications using OpenAirInterface5G

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

Abstract & Overview

Provisioning of 5G services via Non-Terrestrial Networks (5G-NTN) has become a reality. Currently, 5G-NTN is being developed by adapting the 5G Terrestrial Network (5G-TN) protocol which presents several challenges as the satellite channel is significantly different from terrestrial channels. The retransmission mechanism is one of them. Recent works on 5G-NTN have followed the approach of disabling retransmissions from the 5G protocol stack such as Hybrid Automatic Repeat Request (HARQ) at the MAC layer and Automatic Repeat Request (ARQ) at the RLC layer while delegating it to the application layer. This approach degrades the end-user-throughput and latency. In this work, we experimentally study the effect of enabling ARQ retransmission, by using RLC Acknowledged Mode (RLC-AM) in a GEO-based 5G-NTN which is susceptible to packet loss caused by low SNR. We conduct realtime experiments to compare the effects of RLC-AM and RLC Unacknowledged Mode(RLC-Um)on applications(VoIP, video stream, file transfer) using TCP and UDP for different SNR regimes. We have used OpenAirInterface5G-NTN, which is developed to perform realtime 5G-NTN experiments, and a satellite channel emulator. We observe that for low SNR, RLC-AM performs better than RLC-UM in achieving the required bitrate and packet error rate. The reason being RLC-AM recovers the lost packets earlier in the protocol stack without delegating the retransmissions to the application layer. This becomes especially useful when HARQ is disabled. We believe that our experimental study will complement the ongoing theoretical research and help improve the procedures of the Radio Resource Control(RRC) layer in 5G-NTN-specific applications.

Publication Metadata

Authors: Sumit Kumar, Chandan Kumar Sheemar, Jorge Querol, Amirhossein Nik, Symeon Chatzinotas
Venue: 2023 IEEE Globecom Workshops (GC Wkshps) (2023)
Research Areas: 6G-NTN, AI & Neuromorphic SatCom, SDR & Experimental Testbeds
DOI: 10.1109/gcwkshps58843.2023.10464560
Open Access Repository: ORBiLu – University of Luxembourg

Radio Communication Blackout Mitigation: Ray Tracing Analysis and Signal Characterization Including Experimental Validation for Non-magnetized Plasmas

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

Abstract & Overview

Atmospheric entries and hypersonic flights are challenging. The bow shock in front of the vehicle and friction heat the gas flow around the vehicle and result in the ionization of molecules and atoms. This plasma surrounding the spacecraft leads to a total or partial cut-off of radio communication for telecommand, telemetry, and navigation if the plasma frequency is near or exceeds the radio frequency of the communication system. Recent improvements in high-temperature superconducting materials brought back the focus on the magnetic windowing radio communication blackout mitigation method. Within the Horizon 2020 MEESST (Magnetohydrodynamic Enhanced Entry System for Space Transportation) project the effect of an applied magnetic field using a superconductive magnet with a sufficiently strong magnetic field is analyzed. The BlackOut Ray-Tracer (BORAT) was further developed to predict the wave propagation in the plasma in two dimensions for magnetized plasma using the Eikonal solver. A signal characterization model was added for a better understanding of the physics of wave propagation. The latest results for non-magnetized plasma show a good agreement between the numerical solutions and the experiment. The signal characterization allows us to further define brownout scenarios with partially disrupted communication. The effect of a weak applied magnetic field on the ray propagation path and the signal characteristics are discussed leading to the conclusion that the magnetic windowing method is promising to mitigate radio blackout when strong magnetic fields are applied.

Publication Metadata

Authors: Johannes Laur, Diana Luis, Alan Viladegut, Vincent F Giangaspero, Andrea Lani, Jorge Luis González Rios, Jorge Querol, J Peralvo, J Merlano Duncan, AM Hein
Venue: AEC 2023-10th EUCASS-9th CEAS (2023)
Research Areas: RFI Mitigation & GNSS Security, SDR & Experimental Testbeds
DOI: 10.2514/6.2024-1821
Open Access Repository: ORBiLu – University of Luxembourg

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

Non-terrestrial network testbeds for 5G and beyond

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

Abstract & Overview

The fifth generation (5G) of wireless communications offers a plethora of new communications paradigms, scenarios, and services. Among them, the integration of terrestrial and non-terrestrial networks is one of the most relevant aiming at providing seamless ubiquity connectivity and economies of scale for satellite communications. This chapter presents the most relevant experimental testbeds for the demonstration of 5G and beyond 5G adaptations for their use in non-terrestrial networks. In the first sections, a state-of-the-art review is presented including a description of the principal hardware and software components, highlighting OpenAirInterface as the most prominent open-source 5G stack. The latest sections describe the features and capabilities of the most advanced 5G non-terrestrial network testbeds based on OpenAirInterface: the 5G-SpaceLab and the 5G-Lab.

Publication Metadata

Authors: Jorge Querol, Sumit Kumar, Oltjon Kodheli, Abdelrahman Astro, Juan Duncan, Mohammad Gholamian, Rakesh Palisetty, Symeon Chatzinotas, Thomas Heyn, Guido Casati
Venue: Conference Paper (2022)
Research Areas: 6G-NTN, SDR & Experimental Testbeds
DOI: 10.1049/pbte105e_ch16

OpenAirInterface as a platform for 5G-NTN Research and Experimentation

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

Abstract & Overview

Technical advancements and experimental works for the integration of 5G and Non-Terrestrial Networks (NTN) have gained significant traction over the past few years. NTN components have been officially included in the 5G ecosystem by 3GPP in the latest Release-17. 5G-NTN research is ongoing and it is desirable to have a platform that facilitates quick prototyping of the proof-of-concept methods. OpenAirInterface(OAI) is an open-source experimental yet 3GPP standard-compliant Software Defined Radio (SDR) based protocol stack that has been widely known for implementing 4G/5G technologies. Due to its proven capabilities and flexibility, OAI is currently in the developmental process of integrating adaptations for the 5G-NTN. In this work, we discuss the peculiar features of OAI which are shaping it towards becoming a preferred tool for research and experimentation related to 5G-NTN. We provide details of completed/ongoing 5G-NTN projects leveraging OAI to achieve their objectives. In particular, we discuss 5G-GOA and 5G-LEO where critical adaptations in OAI are being done to support 5G-NTN use-cases. Such adaptations enable direct-access between UE and gNB via transparent payload Geostationary (5G-GOA) and Non-geostationary satellites (5G-LEO). Both projects have closely followed 3GPP discussions over 5G-NTN and the adaptations are compliant with the currently frozen 3GPP Release-17. OAI adaptations from both projects will be merged into the main development branch of OAI. We also provide a future roadmap of OAI towards 5G-NTN development. We believe that the pioneering steps taken in the course of the aforementioned projects will establish OAI as a preferred tool for 5G-NTN research and experimentations.

Publication Metadata

Authors: Sumit Kumar, Ashish Kumar Meshram, Abdelrahman Astro, Jorge Querol, Thomas Schlichter, Guido Casati, Thomas Heyn, Florian Völk, Robert T. Schwarz, Andreas Knopp, Paulo Marques, Luis Pereira, Roberto Magueta, Adam Kapovits, Florian Kaltenberger
Venue: 2022 IEEE Future Networks World Forum (FNWF) (2022)
Research Areas: 6G-NTN, AI & Neuromorphic SatCom, SDR & Experimental Testbeds
DOI: 10.1109/fnwf55208.2022.00094
Open Access Repository: ORBiLu – University of Luxembourg

Implementation of a testbed for GNSS-R payload performance evaluation

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

Abstract & Overview

The functional performance of space-borne instruments must be validated on ground before and after satellite integration. The effects of radio-frequency interference are also becoming more important, even in protected bands for earth observation. In this article, a GNSS and GNSS-R signal simulator is developed as part of a testbed of GNSS receivers and GNSS-R payloads’ performance in high dynamics, and to study the effects of RFI in the GNSS-R observables. This article describes the different concepts and key enabling techniques that have been developed to support this project.

Publication Metadata

Authors: Adrián Pérez-Portero, Joan Francesc Muñoz-Martín, Jorge Querol, Hyuk Park, Adriano Camps
Venue: IEEE Journal of Selected Topics in Applied Earth Observations and Remote (2020)
Research Areas: JCAS & Earth Observation, GNSS & Positioning, SDR & Experimental Testbeds
DOI: 10.1109/jstars.2020.2997717

SDR implementation of a testbed for synchronization of coherent distributed remote sensing systems

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

Abstract & Overview

Remote Sensing from distributed platforms has become attractive for the community in the last years. Phase, frequency, and time synchronization are a crucial requirement for many such applications as multi-static remote sensing and also for distributed beamforming for communications. The literature on the field is extensive, and in some cases, the requirements an complexity of the proposed synchronization solution may surpass the ones set by the application itself. Moreover, the synchronization solution becomes even more challenging when the nodes are flying or hovering on aerial or space platforms. In this work, we discuss the synchronization considerations for the implementation of distributed remote sensing applications. The general framework considered is based on a distributed collection of autonomous nodes that synchronize their clocks with a common reference using inter-satellite links. For this purpose, we implement a synchronization link between two nodes operating in a full-duplex fashion. The experimental testbed uses commercially available SDR platforms to emulate two satellites, two targets, and the communication channel. The proposal is evaluated considering phase and frequency errors for different system parameters.

Publication Metadata

Authors: J. C. Merlano-Duncan, Jorge Querol, L. Martinez-Marrero, J. Krivochiza, A. Camps, S. Chatzinotas, B. Ottersten
Venue: IGARSS 2020-2020 IEEE International Geoscience and Remote Sensing Symposium (2020)
Research Areas: JCAS & Earth Observation, SDR & Experimental Testbeds
DOI: 10.1109/igarss39084.2020.9324220
Open Access Repository: ORBiLu – University of Luxembourg

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

Hardware precoding demonstration in multibeam UHTS communications under realistic payload characteristics

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

Abstract & Overview

In this chapter, we present a new hardware test-bed to demonstrate closed-loop precoded communications for interference mitigation in multibeam ultrahigh throughput satellite systems under realistic payload and channel impairments. We build the test-bed to demonstrate a real-time channel aided precoded transmission under realistic conditions such as the power constraints and satellite-payload nonlinearities. We develop a scalable architecture of an SDR platform with the DVB-S2X piloting. The SDR platform consists of two parts: analog-to-digital (ADC) and digital-to-analog (DAC) converters preceded by radio frequency (RF) front end and field-programmable gate array (FPGA) backend. The former introduces realistic impairments in the transmission chain such as carrier frequency and phase misalignments, quantization noise of multichannel ADC and DAC, and nonlinearities of RF components. It allows evaluating the performance of the precoded transmission in a more realistic environment rather than using only numerical simulations. We benchmark the performance of the communication standard in realistic channel scenarios, evaluate received signal SNR, and measure the actual channel throughput using LDPC codes.

Publication Metadata

Authors: Juan Duncan, Jorge Querol, Nicola Maturo, Jevgenij Krivochiza, Danilo Spano, Norshahida Saba, Liz Marrero, Symeon Chatzinotas, Björn Ottersten
Venue: Advances in Communications Satellite Systems. Proceedings of the 37th (2019)
Research Areas: Beamforming & MIMO, SDR & Experimental Testbeds
DOI: 10.1049/pbte095e_ch66
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

MERITXELL: the Multifrequency Experimental Radiometer with Interference Tracking for Experiments over Land and Littoral—instrument description, calibration and performance

Sun, 01 Jan 2017 00:00:00 +0000

Abstract & Overview

MERITXELL is a ground-based multisensor instrument that includes a multiband dual-polarization radiometer, a GNSS reflectometer, and several optical sensors. Its main goals are twofold: to test data fusion techniques, and to develop Radio-Frequency Interference (RFI) detection, localization and mitigation techniques. The former is necessary to retrieve complementary data useful to develop geophysical models with improved accuracy, whereas the latter aims at solving one of the most important problems of microwave radiometry. This paper describes the hardware design, the instrument control architecture, the calibration of the radiometer, and several captures of RFI signals taken with MERITXELL in urban environment. The multiband radiometer has a dual linear polarization total-power radiometer topology, and it covers the L-, S-, C-, X-, K-, Ka-, and W-band. Its back-end stage is based on a spectrum analyzer structure which allows to perform real-time signal processing, while the rest of the sensors are controlled by a host computer where the off-line processing takes place. The calibration of the radiometer is performed using the hot-cold load procedure, together with the tipping curves technique in the case of the five upper frequency bands. Finally, some captures of RFI signals are shown for most of the radiometric bands under analysis, which evidence the problem of RFI in microwave radiometry, and the limitations they impose in external calibration.

Publication Metadata

Authors: Jorge Querol, J. M. Tarongíi, Giuseppe Forte, Joséé Luís Eguia Gómez, Adriano Camps
Venue: Sensors (2017)
Research Areas: JCAS & Earth Observation, RFI Mitigation & GNSS Security, SDR & Experimental Testbeds
DOI: 10.3390/s17051081