JCAS & Earth Observation | Dr. Jorge Querol

Holographic Joint Communications and Sensing With Cramér-Rao Bounds

Thu, 01 Jan 2026 00:00:00 +0000

Abstract & Overview

This research contribution by Chandan Kumar Sheemar, Wali Ullah Khan, George C. Alexandropoulos, Jorge Querol et al. (2026), published in IEEE Journal on Selected Areas in Communications, investigates “Holographic Joint Communications and Sensing With Cramér-Rao Bounds” within the domains of JCAS & Earth Observation, Beamforming & MIMO. 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: Chandan Kumar Sheemar, Wali Ullah Khan, George C. Alexandropoulos, Jorge Querol, Symeon Chatzinotas
Venue: IEEE Journal on Selected Areas in Communications (2026)
Research Areas: JCAS & Earth Observation, Beamforming & MIMO
DOI: 10.1109/jsac.2025.3613282

RIS-Enabled Joint Communications and Sensing in 6G NTNs: Opportunities and Challenges

Thu, 01 Jan 2026 00:00:00 +0000

Abstract & Overview

The integration of Joint Communications and Sensing (JCAS) and Reconfigurable Intelligent Surfaces (RIS) is poised to be a cornerstone of Sixth-Generation (6G) Non-Terrestrial Networks (NTNs), enabling unprecedented capabilities for ubiquitous connectivity and high-resolution environmental monitoring. While the synergy between RIS and JCAS in terrestrial networks has been explored, its application in the unique and stratified environment of NTNs presents distinct opportunities and challenges across different propagation domains. This paper provides a comprehensive analysis of RIS-enabled JCAS for 6G NTNs, with a specific focus on differentiating the operational landscape between the space layer and the atmospheric layer. We identify novel key opportunities in the atmospheric layer, including uncrewed aerial vehicles (UAVs) and high-altitude platforms (HAPSs), and the space layer, including, low-Earth orbit, medium Earth orbit, and Geostationary orbit (GEO), and present and discuss the future challenges to be addressed to realize the integration of RIS a reality for the next-generation JCAS for NTNs.

Publication Metadata

Authors: Wali Ullah Khan, Chandan Kumar Sheemar, Muhammad Ali Jamshed, Eva Lagunas, Jorge Querol, Aryan Kaushik, Symeon Chatzinotas
Venue: IEEE Open Journal of the Communications Society (2026)
Research Areas: 6G-NTN, JCAS & Earth Observation
DOI: 10.1109/ojcoms.2026.3655070

Joint Communications and Sensing for 6G Satellite Networks: Use Cases and Challenges

Thu, 09 Jan 2025 00:00:00 +0000

Abstract & Overview

Satellite networks (SN) have long provided two fundamental services: global communications and Earth-oriented sensing, supporting applications from connectivity and navigation to disaster management and environmental monitoring. Yet, the accelerating demand for data and the emergence of new applications render the independent evolution of communication and sensing payloads increasingly unsustainable. Joint communications and sensing (JCAS) has emerged as a transformative paradigm, integrating both functions within a unified payload to enhance spectral efficiency, reduce operational costs, and minimize hardware redundancy. Beyond efficiency, this integration creates opportunities for novel services that are infeasible under separate payload designs. This paper motivates the role of JCAS in shaping the sixth-generation (6G) of satellite networks, explores a representative use case to assess its feasibility, and discusses key challenges that must be addressed to unlock its full potential. By highlighting these opportunities inherent to the space environment, we aim to stimulate the development of JCAS as a cornerstone technology for the next-generation space era

Publication Metadata

Authors: Chandan Kumar Sheemar, Prabhu Thiruvasagam, Wali Ullah Khan, Sourabh Solanki, George C. Alexandropoulos, Jorge Querol, Plachy, Jan, Oliver Holschke, Symeon Chatzinotas
Venue: arXiv (Cornell University) (2025)
Research Areas: 6G-NTN, Satellite Communications, JCAS & Earth Observation
DOI: 10.48550/arxiv.2501.05243

Joint Communication and Navigation From LEO Multi-Beam Satellite

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

Abstract & Overview

This paper investigates an innovative approach to enable Joint Communication and Positioning (JCAP) in 5G Non-Terrestrial Networks (NTN) using Low Earth Orbit (LEO) multi-beam satellite systems. The integration of communication and navigation services is achieved by aggregating a Direct-Sequence Spread Spectrum (DSSS) as a navigation signal with a 5G Orthogonal Frequency-Division Multiplexing (OFDM) waveform for communication services. Two models are proposed for resource allocation and signal aggregation, referred to as the shared beam model, where communication and navigation signals are aggregated prior to Digital Beamforming (DBF) within the same beam; and the independent beam model, which employs separate beams for communication and navigation, with the navigation beam designed to be significantly wider than the communication beams, resulting in overlap between the two. The performance of these models is assessed using as Key Performance Indicators (KPI) the Cramer-Rao Lower Bound (CRLB) for range estimation used in navigation and the spectral efficiency for the broadband service. The study formulates and addresses a multi-objective optimization problem to derive the Pareto front, highlighting the trade-off between communication and navigation performance. Extensive simulations demonstrate the efficacy of the proposed models in terms of spectral efficiency and accuracy in range estimation, and results have been compared with those obtained from the current 5G positioning system. The models have been evaluated in two distinct scenarios: one without frequency reuse between beams and another incorporating a three-color frequency reuse scheme. The results indicate that the independent beams model outperforms the shared beams model by reducing inter-beam interference in both scenarios. The proposed solution maintains backward compatibility with existing 5G NTN, facilitating uninterrupted positioning and communication services in GNSS-denied environments. Furthermore, the combination of DSSS and OFDM enhances the reliability of the data service by utilizing the DSSS sequence as a digital signature for the waveform. This work establishes a foundation for robust and efficient JCAP implementations, addressing challenges related to multi-beam interference and resource optimization.

Publication Metadata

Authors: Alejandro Gonzalez-Garrido, Jorge Querol, Henk Wymeersch, Symeon Chatzinotas
Venue: IEEE Open Journal of the Communications Society (2025)
Research Areas: Satellite Communications, JCAS & Earth Observation, GNSS & Positioning, Beamforming & MIMO
DOI: 10.1109/ojcoms.2025.3568093
Open Access Repository: ORBiLu – University of Luxembourg

Joint Communication and Positioning Receiver Architecture for DSSS-Overlayed OFDM Waveform

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

Abstract & Overview

The integration of satellite systems within the 5G new radio (NR) framework, designated as non-terrestrial networks (NTNs), relies on global navigation satellite systems (GNSS) to achieve precise synchronization. However, dependence on GNSS presents significant vulnerabilities in scenarios involving signal degradation, jamming, or spoofing, alongside increased cost and power consumption issues, particularly in extensive internet of things (IoT) deployments. To address these challenges, this paper proposes an innovative joint communication and positioning (JCAP) receiver architecture, which integrates direct sequence spread spectrum (DSSS) signals into the 5G orthogonal frequency division multiplexing (OFDM) waveform, enabling GNSS-free synchronization and positioning capabilities without embedded pilot overhead. The proposed hybrid architecture jointly exploits DSSS for robust channel parameter estimation and OFDM for high-throughput communication, thereby reducing the pilots signals traditionally required for synchronization and channel estimation. Comprehensive evaluations demonstrate that the proposed JCAP receiver achieves reliable detection and accurate estimation of delay and Doppler parameters, maintaining low bit error rates (BER) under realistic signal-to-interference ratios (SIR). The findings underscore the feasibility and effectiveness of the proposed hybrid scheme, paving the way for resilient GNSS-free operations in 5G NTN environments.

Publication Metadata

Authors: Alejandro Gonzalez-Garrido, Idir Edjekouane, Jorge Querol, Henk Wymeersch, Symeon Chatzinotas
Venue: IEEE Open Journal of the Communications Society (2025)
Research Areas: JCAS & Earth Observation, GNSS & Positioning
DOI: 10.1109/ojcoms.2025.3615957

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

Development of a Dynamically Re-Configurable Radio-Frequency Interference Detection System for L-Band Microwave Radiometers

Fri, 21 Jun 2024 00:00:00 +0000

Abstract & Overview

Real-Time RFI Detection and Flagging (RT-RDF) for microwave radiometers is a versatile new FPGA algorithm designed to detect and flag Radio-Frequency Interference (RFI) in microwave radiometers. This block utilizes computationally-efficient techniques to identify and analyze RF signals, allowing the system to take appropriate measures to mitigate interference and maintain reliable performance. With L-Band microwave radiometry as the main application, this RFI detection algorithm focuses on the Kurtogram and Spectrogram to detect non-Gaussian behavior. To gain further modularity, an FFT-based filter bank is used to divide the receiver’s bandwidth into several sub-bands within the band of interest of the instrument, depending on the application. Multiple blanking strategies can then be applied in each band using the provided detection flags. The algorithm can be re-configured in the field, for example with dynamic integration times to support operation in different environments, or configurable thresholds to account for variable RFI environments. A validation and testing campaign has been performed on multiple scenarios with the ARIEL commercial microwave radiometer, and the results confirm the excellent performance of the system.

Publication Metadata

Authors: Adrián Pérez-Portero, Jorge Querol, Andreu Mas-Viñolas, A. Amézaga, R. Jove‐Casulleras, Adriano Camps
Venue: Sensors (2024)
Research Areas: JCAS & Earth Observation, RFI Mitigation & GNSS Security
DOI: 10.3390/s24134034
Open Access Repository: ORBiLu – University of Luxembourg

Full-duplex-enabled joint communications and sensing with reconfigurable intelligent surfaces

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

Abstract & Overview

The full-duplex (FD) technology has the potential to radically evolve wireless systems, facilitating the integration of both communications and radar functionalities into a single device, thus, enabling joint communication and sensing (JCAS). In this paper, we present a novel approach for JCAS that incorporates a reconfigurable intelligent surface (RIS) in the near-field of an FD multiple-input multiple-output (MIMO) node, which is jointly optimized with the digital beamformers to enable JSAC and efficiently handle self-interference (SI). We propose a novel problem formulation for FD MIMO JCAS systems to jointly minimize the total received power at the FD node’s radar receiver, while maximizing the sum rate of downlink communications subject to a Cramer-Rao bound (CRB) constraint. In contrast to the typically used CRB in the relevant literature, we derive a novel, more accurate, target estimation bound that fully takes into account the RIS deployment. The considered problem is solved using alternating optimization, which is guaranteed to converge to a local optimum. The simulation results demonstrate that the proposed scheme achieves significant performance improvement both for communications and sensing. It is showcased that, jointly designing the FD MIMO beamformers and the RIS phase configuration to be SI aware can significantly loosen the requirement for additional SI cancellation.

Publication Metadata

Authors: Chandan Kumar Sheemar, George C. Alexandropoulos, Dirk Slock, Jorge Querol, Symeon Chatzinotas
Venue: 2023 31st European Signal Processing Conference (EUSIPCO) (2023)
Research Areas: JCAS & Earth Observation
DOI: 10.23919/eusipco58844.2023.10289881
Open Access Repository: ORBiLu – University of Luxembourg

RFI detection and mitigation for advanced correlators in interferometric radiometers

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

Abstract & Overview

This work presents the first RFI detection and mitigation algorithm for the interferometric radiometers that will be implemented in its correlator unit. The algorithm operates in the time and frequency domains, applying polarimetric and statistical tests in both domains, and exhibiting a tunable and arbitrary low probability of false alarm. It is scalable to a configurable number of receivers, and it is optimized in terms of quantization bits and the implementation of the cross-correlations in the time or frequency domains for hardware resource saving. New features of this algorithm are the computation of the Stokes parameters per frequency bin in the Short-Time Fourier Transform and a new parameter called Polarimetric Kurtosis. If RFI is detected in one domain or in both, it is removed using the calculated blanking masks. The optimum algorithm parameters are computed, such as length of the FFTs, the threshold selection for a given probability of false alarm, and the selection of the blanking masks. Last, an important result refers to the application of Parseval’s theorem for the computation of the cross-correlations in the frequency domain, instead of in the time domain, which is more efficient and leads to smaller errors even when using moderate quantization levels. The algorithm has been developed in the framework of the ESA’s technology preparation for a potential L-band radiometer mission beyond SMOS. However, it is also applicable to (polarimetric) real aperture radiometers, and its performance would improve if more than one bit is used in the signal quantization.

Publication Metadata

Authors: Adrián Pérez-Portero, Jorge Querol, Adriano Camps, Manuel Martín‐Neira, Martin Süess, Juan Ignacio Ramirez, Alberto Zurita, Joséep Closa, Roger Oliva, R. Onrubia
Venue: Remote Sensing (2022)
Research Areas: JCAS & Earth Observation, RFI Mitigation & GNSS Security
DOI: 10.3390/rs14184672

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

A pre-correlation RFI mitigation algorithm for L-band interferometric radiometers

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

Abstract & Overview

Radio Frequency Interference (RFI) is a major concern for both real and synthetic aperture radiometers. After the lessons learnt from SMOS, ESA is preparing the next generation of L-band interferometric radiometers with RFI mitigation integrated into the cross-correlators. This work presents a preliminary design and results of a pre-correlation RFI mitigation algorithm tailored for interferometric radiometers. The results show that the correlation error introduced by the RFI is reduced on average to the half, with peaks of 20 dB of mitigation.

Publication Metadata

Authors: Jorge Querol, A. Camps, A. Perez, R. Oliva, R. Onrubia, J. I. Ramirez-Martinez, A. Zurita, M. Suess, M. Martin-Neira
Venue: 2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS (2021)
Research Areas: JCAS & Earth Observation, RFI Mitigation & GNSS Security
DOI: 10.1109/igarss47720.2021.9553195

A remote carrier synchronization technique for coherent distributed remote sensing systems

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

Abstract & Overview

Phase, frequency, and time synchronization are crucial requirements for many applications, such as multistatic remote sensing and communication systems. Moreover, the synchronization solution becomes even more challenging when the nodes are orbiting or flying on airborne or spaceborne platforms. This article compares the available technologies used for the synchronization and coordination of nodes in distributed remote sensing applications. Additionally, this article proposes a general system model and identifies preliminary guidelines and critical elements for implementing the synchronization mechanisms exploiting the intersatellite communication link. The distributed phase synchronization loop introduced in this work deals with the self-interference in a full-duplex point to point scenario by transmitting two carriers at each node. All carriers appear with different frequency offsets around a central frequency, called the application central-frequency or the beamforming frequency. This article includes a detailed analysis of the proposed algorithm and the required simulations to verify its performance for different phase noise, additive white Gaussian noise, and Doppler shift scenarios.

Publication Metadata

Authors: Juan Carlos Merlano Duncán, Liz Martínez Marrero, Jorge Querol, Sumit Kumar, Adriano Camps, Symeon Chatzinotas, Björn Ottersten
Venue: IEEE Journal of Selected Topics in Applied Earth Observations and Remote (2020)
Research Areas: JCAS & Earth Observation
DOI: 10.1109/jstars.2020.3046776
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

L-band vegetation optical depth estimation using transmitted GNSS signals: Application to GNSS-reflectometry and positioning

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

Abstract & Overview

At L-band (1–2 GHz), and particularly in microwave radiometry (1.413 GHz), vegetation has been traditionally modeled with the τ-ω model. This model has also been used to compensate for vegetation effects in Global Navigation Satellite Systems-Reflectometry (GNSS-R) with modest success. This manuscript presents an analysis of the vegetation impact on GPS L1 C/A (coarse acquisition code) signals in terms of attenuation and depolarization. A dual polarized instrument with commercial off-the-shelf (COTS) GPS receivers as back-ends was installed for more than a year under a beech forest collecting carrier-to-noise (C/N0) data. These data were compared to different ground-truth datasets (greenness, blueness, and redness indices, sky cover index, rain data, leaf area index or LAI, and normalized difference vegetation index (NDVI)). The highest correlation observed is between C/N0 and NDVI data, obtaining R2 coefficients larger than 0.85 independently from the elevation angle, suggesting that for beech forest, NDVI is a good descriptor of signal attenuation at L-band, which is known to be related to the vegetation optical depth (VOD). Depolarization effects were also studied, and were found to be significant at elevation angles as large as ~50°. Data were also fit to a simple τ-ω model to estimate a single scattering albedo parameter (ω) to try to compensate for vegetation scattering effects in soil moisture retrieval algorithms using GNSS-R. It is found that, even including dependence on the elevation angle (ω(θe)), at elevation angles smaller than ~67°, the ω(θe) model is not related to the NDVI. This limits the range of elevation angles that can be used for soil moisture retrievals using GNSS-R. Finally, errors of the GPS-derived position were computed over time to assess vegetation impact on the accuracy of the positioning.

Publication Metadata

Authors: Adriano Camps, Alberto Alonso-Arroyo, Hyuk Park, Raul Onrubia, Daniel Pascual, Jorge Querol
Venue: Remote sensing (2020)
Research Areas: JCAS & Earth Observation, GNSS & Positioning, Quantum & Optical Space Links
DOI: 10.3390/rs12152352

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

Technology developments for an advanced l-band radiometer mission

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

Abstract & Overview

ESA’s Soil Moisture and Ocean Salinity (SMOS) mission was launched 2 Nov 2009 and, to date, is still in good health, providing valuable L-band observations of the Earth surface [1]. A number of products are obtained from these, including thin sea ice [2], frost/thaw soils [3], high winds [4], ocean surface wind [5] and Sun brightness temperature [6], besides the main mission measurements of soil moisture and sea surface salinity [7] [8]. This paper deals with the description and early results of some technology activities conducted by ESA applying the lessons learnt by SMOS and in preparation of an advanced L-band radiometer mission.

Publication Metadata

Authors: Manuel Martin-Neira, Martin Suess, Nikos Karafolas, Petri Piironen, Francois Deborgies, Albert Catalan, Roger Vilaseca, Josée Montero, Montserrat Puertolas, Diego Outumuro, Ignasi Corbella, Israel Duran, Nuria Duffo, Roberto Materni, Teresa Mengual, Miguel Angel Piqueras, Ana Olea, Andres Solana, Joséep Closa, Albert Zurita, Juan Ignacio Ramirez, Olav Breinbjerg, Jeppe Majlund Bjorstorp, Kyriakos Kaslis, Steen S. Kristensen, Roger Oliva, Raul Onrubia, Adriano Camps, Jorge Querol
Venue: IGARSS 2020-2020 IEEE International Geoscience and Remote Sensing Symposium (2020)
Research Areas: JCAS & Earth Observation
DOI: 10.1109/igarss39084.2020.9324378

Architectures and synchronization techniques for coherent distributed remote sensing systems

Sun, 28 Jul 2019 00:00:00 +0000

Abstract & Overview

Coherent Distributed Remote Sensing Systems require strict time, frequency, and phase synchronization across distributed satellite nodes. This paper analyzes distributed architectures and wireless inter-satellite synchronization techniques suitable for coherent multistatic SAR, interferometric radiometry, and GNSS reflectometry missions.

Publication Metadata

Authors: Juan Carlos Merlano-Duncan, Jorge Querol, Adriano Camps, Symeon Chatzinotas, Björn Ottersten
Venue: IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium (2019)
Research Areas: JCAS & Earth Observation
DOI: 10.1109/IGARSS.2019.8898444
Open Access Repository: ORBiLu

A review of RFI mitigation techniques in microwave radiometry

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

Abstract & Overview

Radio frequency interference (RFI) is a well-known problem in microwave radiometry (MWR). Any undesired signal overlapping the MWR protected frequency bands introduces a bias in the measurements, which can corrupt the retrieved geophysical parameters. This paper presents a literature review of RFI detection and mitigation techniques for microwave radiometry from space. The reviewed techniques are divided between real aperture and aperture synthesis. A discussion and assessment of the application of RFI mitigation techniques is presented for each type of radiometer.

Publication Metadata

Authors: Jorge Querol, Adrián Pérez-Portero, Adriano Camps
Venue: Remote Sensing (2019)
Research Areas: JCAS & Earth Observation, RFI Mitigation & GNSS Security
DOI: 10.3390/rs11243042
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

Radio frequency interference detection and mitigation techniques for navigation and Earth observation

Fri, 09 Nov 2018 00:00:00 +0000

Abstract & Overview

This PhD thesis is devoted to the design, implementation, and experimental validation of innovative Radio-Frequency Interference (RFI) detection, localization, and mitigation countermeasures in the fields of Microwave Radiometry (MWR), Global Navigation Satellite Systems (GNSS), and GNSS-Reflectometry (GNSS-R). It completes the development of the MERITXELL multi-frequency radiometer, introduces the Multiresolution Fourier Transform (MFT) mitigation algorithm, proposes the Generalized Spectral Separation Coefficient (GSSC) metric for GNSS-R under interference, and presents the patented FENIX real-time pre-correlation anti-jamming architecture (US Patent US9596610B1), demonstrating up to 30 dB of jamming resilience across GPS L1 C/A, GPS L2C, and Galileo E1OS signals. Awarded Best PhD Thesis 2018 by the IEEE Geoscience and Remote Sensing Society (GRSS) Spanish Chapter.