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

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

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

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

MEC-assisted low latency communication for autonomous flight control of 5G-connected UAV

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

Abstract & Overview

Proliferating applications of unmanned aerial vehicles (UAVs) impose new service requirements, leading to several challenges. One of the crucial challenges in this vein is to facilitate the autonomous navigation of UAVs. Concretely, the UAV needs to individually process the visual data and subsequently plan its trajectories. Since the UAV has limited onboard storage constraints, its computational capabilities are often restricted and it may not be viable to process the data locally for trajectory planning. Alternatively, the UAV can send the visual inputs to the ground controller which, in turn, feeds back the command and control signals to the UAV for its safe navigation. However, this process may introduce some delays, which is not desirable for autonomous UAVs’ safe and reliable navigation. Thus, it is essential to devise techniques and approaches that can potentially offer low-latency solutions for planning the UAV’s flight. To this end, this paper analyzes a multi-access edge computing aided UAV and aims to minimize the latency of the task processing. More specifically, we propose an offloading strategy for a UAV by optimally designing the offloading parameter, local computational resources, and altitude of the UAV. The numerical and simulation results are presented to offer various design insights, and the benefits of the proposed strategy are also illustrated in contrast to the other baseline approaches.

Publication Metadata

Authors: Sourabh Solanki, Asad Mahmood, Vibhum Singh, Sumit Gautam, Jorge Querol, Symeon Chatzinotas
Venue: 2023 IEEE 97th Vehicular Technology Conference (VTC2023-Spring) (2023)
Research Areas: 6G-NTN
DOI: 10.1109/vtc2023-spring57618.2023.10200917
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

Robust Beamforming for IRS Aided MIMO Full Duplex Systems

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

Abstract & Overview

In this paper, a novel robust beamforming for an intelligent reflecting surface (IRS) assisted FD system is presented. Since perfect channel state information (CSI) is often challenging to acquire in practice, we consider the case of imperfect CSI and adopt a statistically robust beamforming approach to maximize the ergodic weighted sum rate (WSR). We also analyze the achievable WSR of an IRS-assisted FD with imperfect CSI, for which the lower and the upper bounds are derived. The ergodic WSR maximization problem is tackled based on the expected Weighted Minimum Mean Squared Error (WMMSE), which is guaranteed to converge to a local optimum. The effectiveness of the proposed design is investigated with extensive simulation results. It is shown that our robust design achieves significant performance gain compared to the naive beamforming approaches and considerably outperforms the robust Half-Duplex (HD) system.

Publication Metadata

Authors: Chandan Kumar Sheemar, Jorge Querol, Sourabh Solanki, Sumit Kumar, Symeon Chatzinotas
Venue: GLOBECOM 2023-2023 IEEE Global Communications Conference (2023)
Research Areas: AI & Neuromorphic SatCom, Beamforming & MIMO
DOI: 10.48550/arxiv.2308.08016

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

Signal Processing Based Antenna Pattern Characterization for MIMO Systems

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

Abstract & Overview

Sophisticated antenna technologies are constantly evolving to meet the escalating data demands projected for 6G and future networks. The characterization of these emerging antenna systems poses challenges that necessitate a reevaluation of conventional techniques, which rely solely on simple measurements conducted in advanced anechoic chambers. In this study, our objective is to introduce a novel endeavour for antenna pattern characterization (APC) in next-generation multiple-input-multiple-output (MIMO) systems by utilizing the potential of signal processing tools. In contrast to traditional methods that struggle with multi-path scenarios and require specialized equipment for measurements, we endeavour to estimate the antenna pattern by exploiting information from both line-of-sight (LoS) and non-LoS contributions. This approach enables antenna pattern characterization in complex environments without the need for anechoic chambers, resulting in substantial cost savings. Furthermore, it grants a much wider research community the ability to independently perform APC for emerging complex 6G antenna systems, without relying on anechoic chambers. Simulation results demonstrate the efficacy of the proposed novel approach in accurately estimating the true antenna pattern.

Publication Metadata

Authors: Chandan Kumar Sheemar, Jorge Querol, Symeon Chatzinotas
Venue: 2023 International Conference on Software, Telecommunications and Computer (2023)
Research Areas: Beamforming & MIMO
DOI: 10.23919/softcom58365.2023.10271685
Open Access Repository: ORBiLu – University of Luxembourg

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 space communications lab: Reaching new heights

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

Abstract & Overview

The new era of space exploration demands a significant increase in the number of human and robotic missions, thus resulting in novel communication and service requirements. To satisfy such requirements, the fifth generation of mobile communication systems (5G), despite providing connectivity on Earth, has the potential to serve as a communication standard for space resource missions, particularly the ones targeting the Moon. In fact, 5G non-terrestrial networks (NTNs) are already in the standardization process and new techniques are being proposed in order to counteract the peculiarities of the non-terrestrial channel. However, going one step ahead and deploying constellations of satellites around the Earth or the Moon, requires first a detailed analysis and testing of the validity of the proposed techniques. Therefore, in this paper, we introduce the 5G Space Communications Lab, which has been developed with the purpose of simulating space-based 5G communications. The designed testbed proposed here increases the technology readiness level (TRL) of NTN-based 5G systems, demonstrating over a laboratory environment successful 5G communication via space links.

Publication Metadata

Authors: Oltjon Kodheli, Jorge Querol, Abdelrahman Astro, Sofia Coloma, Loveneesh Rana, Zhanna Bokal, Sumit Kumar, Carol Martinez Luna, Jan Thoemel, Juan Carlos Merlano Duncan, Miguel Angel Olivares Mendez, Symeon Chatzinotas, Bjorn Ottersten
Venue: 2022 18th International Conference on Distributed Computing in Sensor (2022)
Research Areas: 6G-NTN
DOI: 10.1109/dcoss54816.2022.00063
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

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

Hybridization of GNSS and 5G Measurements for Assured Positioning, Navigation and Timing

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

Abstract & Overview

Positioning, Navigation and Timing (PNT) services based on the Global Navigation Satellite System (GNSS) have a number of known drawbacks that makes them prone to suffer a disruption. These flaws can be exploited to disable this service in critical infrastructures. Therefore, the hybridization of GNSS and 5G measurements enabling Assured PNT (APNT) services is growing up and gaining attention by governmental bodies. 5G signals emitted by terrestrial networks and by Low Earth Orbit (LEO) satellites can complement GNSS, enhancing their reliability, security and accuracy. For example, the larger Signal-to-Noise Ratio (SNR) of a terrestrial system makes them more difficult to suffer a jamming attack as compared to GNSS signals. A joint data and positioning signal enhances the security and reliability of the APNT solution with, for example, the successful decoding of encrypted data, this could be used for system authentication. Moreover, a larger signal bandwidth increases the accuracy of the PNT solution. All of these benefits can be extracted from the 5G terrestrial and non-terrestrial networks that transmit the Positioning Reference Signal (PRS). The rationale for these benefits rely on the flexibility of this pilot signal in terms of bandwidth or symbols used for the APNT service. This paper aims to analyse how this flexibility can be optimized to achieve a specific level of accuracy, minimizing the resources used under certain constrains of bandwidth or latency. The results present the optimal parameters to design a 5G PRS waveform with a target scenario constrains. Then, we compare it with the GNSS service and how to benefit when using them in combination. Finally, the paper concludes with the future research lines proposing a joint communications and positioning system as a closed loop. In such scenario, the user achieved accuracy is sent back to the infrastructure, and using the dynamic PRS flexibility, the system increases or reduces the PRS resources in order to meet the user accuracy requirements.

Publication Metadata

Authors: Alejandro Gonzalez-Garrido, Jorge Querol, Symeon Chatzinotas
Venue: Proceedings of the 35th International Technical Meeting of the Satellite (2022)
Research Areas: 6G-NTN, GNSS & Positioning
DOI: 10.33012/2022.18385
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

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

5G-SpaceLab

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

Abstract & Overview

This research contribution by Jorge Querol, Abdelrahman Abdalla, Zhanna Bokal, Juan Carlos Merlano Duncan et al. (2021), published in 2021 Space Resources Week, investigates “5G-SpaceLab” within the domains of 6G-NTN. 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: Jorge Querol, Abdelrahman Abdalla, Zhanna Bokal, Juan Carlos Merlano Duncan, Mohammad Gholamian, Oltjon Kodheli, Jevgenij Krivochiza, Sumit Kumar, Carol Martinez Luna, Nicola Maturo
Venue: 2021 Space Resources Week (2021)
Research Areas: 6G-NTN

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 design strategy for phase synchronization in Precoding-enabled DVB-S2X user terminals

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

Abstract & Overview

This paper address the design of a phase tracking block for the DVB-S2X user terminals in a satellite precoding system. The spectral characteristics of the phase noise introduced by the oscillator, the channel, and the thermal noise at the receiver are taken into account. Using the expected phase noise mask, the optimal parameters for a second-order PLL intended to track channel variations from the pilots are calculated. To validate the results a Simulink model was implemented considering the characteristics of the hardware prototype. The performance of the design was evaluated in terms of the accuracy and stability for the frame structure of superframe Format 2, as described in Annex E of DVB-S2X.

Publication Metadata

Authors: Liz Martinez Marrero, Juan Carlos Merlano Duncan, Jorge Querol, Symeon Chatzinotas, Adriano Camps, Bjorn Ottersten
Venue: ICC 2021-IEEE International Conference on Communications (2021)
Research Areas: Beamforming & MIMO
DOI: 10.1109/icc42927.2021.9500634
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

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

Solar-Aerodynamic Formation Flight for 5G Experiments

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

Abstract & Overview

This research contribution by Jan Thoemel, Jorge Querol, Zhanna Bokal, Juan Carlos Merlano Duncan et al. (2021), published in Proceedings of the 12th European CubeSatSymposium, investigates “Solar-Aerodynamic Formation Flight for 5G Experiments” within the domains of 6G-NTN. 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: Jan Thoemel, Jorge Querol, Zhanna Bokal, Juan Carlos Merlano Duncan, Mohammad Gholamian, Oltjon Kodheli, Sumit Kumar, Carol Martinez Luna, Nicola Maturo, Loveneesh Rana
Venue: Proceedings of the 12th European CubeSatSymposium (2021)
Research Areas: 6G-NTN

Radio-frequency interference location, detection and classification using deep neural networks

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

Abstract & Overview

Global Navigation Satellite System (GNSS) signals are used in Earth Observation for Radio Occultation and Reflectometry. The increasing effects of Radio-Frequency Interferences (RFI) on the performance of these receivers and navigation have suddenly sparked serious concerns due to their proliferation. Detection and mitigation of RFI heavily relies on the nature and location of the interfering sources. In some cases, null-steering or shielding can be used to mitigate RFI effects. In this work, a system to detect and locate RFI sources is presented, including signal classification and recording for countermeasure-related decision-making.

Publication Metadata

Authors: A. Perez, Jorge Querol, H. Park, A. Camps
Venue: IGARSS 2020-2020 IEEE International Geoscience and Remote Sensing Symposium (2020)
Research Areas: RFI Mitigation & GNSS Security, AI & Neuromorphic SatCom
DOI: 10.1109/igarss39084.2020.9324532

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

Real-time Radio Frequency Interference Detection and Mitigation with the Front-End GNSS Interference eXcisor (FENIX)

Mon, 23 Sep 2019 00:00:00 +0000

Abstract & Overview

This paper presents the real-time hardware architecture and experimental evaluation of the Front-End GNSS Interference eXcisor (FENIX), demonstrating standalone pre-correlation time-frequency excision of continuous-wave, chirp, and pulsed jamming signals across civilian GNSS bands.

Publication Metadata

Authors: Jorge Querol, Adrián Pérez-Portero, Joan Francesc Muñoz-Martín, Adriano Camps
Venue: RFI 2019 - Coexisting with Radio Frequency Interference (2019)
Research Areas: RFI Mitigation & GNSS Security, GNSS & Positioning
DOI: 10.1109/RFI48793.2019.9111819
Open Access Repository: ORBiLu

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

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

Effects of differential oscillator phase noise in precoding performance

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

Abstract & Overview

This research contribution by L. Martinez Marrero, J.C. Merlano Duncan, Jorge Querol, S. Chatzinotas et al. (2019), published in Advances in Communications Satellite Systems. Proceedings of the 37th, investigates “Effects of differential oscillator phase noise in precoding performance” within the domains of 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: L. Martinez Marrero, J.C. Merlano Duncan, Jorge Querol, S. Chatzinotas, A.J. Camps Carmona, B. Ottersten
Venue: Advances in Communications Satellite Systems. Proceedings of the 37th (2019)
Research Areas: Beamforming & MIMO
DOI: 10.1049/cp.2019.1261

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

On the new architecture and capabilities of the front-end GNSS interference excisor (FENIX)

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

Abstract & Overview

The number of applications based on Global Navigation Satellite Systems (GNSS) has been increasing in the last years. With its proliferation, Radio-Frequency Interference (RFI) has become one of the most concerning topics on GNSS-based devices for navigation, positioning and timing, but also for Earth Observation purposes such as GNSS-Reflectometry and Radio Occultations due to the corruption of the received signal and the corresponding geophysical measurements. The Front-End GNSS Interference eXcisor (FENIX) mitigates the problem of RFI by providing a plug and play solution to excise interferences out of virtually any system. The new version of FENIX is also capable of operating with large signal bandwidths (~50 MHz) and dual-frequency applications. This paper shows the performance of the system for commercial GNSS receivers and GNSS-reflectometry applications. A discussion of the impact of the new architecture on its future capabilities is presented as well.

Publication Metadata

Authors: Adrián Pérez, Adriano Camps, Jorge Querol
Venue: IGARSS 2019-2019 IEEE International Geoscience and Remote Sensing Symposium (2019)
Research Areas: RFI Mitigation & GNSS Security, GNSS & Positioning
DOI: 10.1109/igarss.2019.8900263

‘Ionospheric scintillation impact on GNSS-R altimetry

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

Abstract & Overview

This research contribution by A Camps, H Park, E Lancheros, R Onrubia et al. (2018), published in GNSS+ R, Ann Arbor, MI, USA, Tech. Rep, investigates “‘Ionospheric scintillation impact on GNSS-R altimetry” within the domains of JCAS & Earth Observation, GNSS & Positioning, Quantum & Optical Space Links. 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: A Camps, H Park, E Lancheros, R Onrubia, D Pascual, Jorge Querol
Venue: GNSS+ R, Ann Arbor, MI, USA, Tech. Rep (2018)
Research Areas: JCAS & Earth Observation, GNSS & Positioning, Quantum & Optical Space Links

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

An anti-jamming system for GNSS timing applications

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

Abstract & Overview

Radio-Frequency Interference (RFI) and jamming are increasing problems for timing applications based on Global Navigation Satellite Systems (GNSS). FENIX-lite is a real-time pre-correlation anti-jamming system designed to provide increased resilience against RFI/jamming in critical GNSS-enabled applications. This work aims to evaluate the combined performance of FENIX-lite and a timing setup composed by two GNSS disciplined oscillators named DOWR. The results show that FENIX provides an anti-jamming resilience of 10-30 dB, at the expense of introducing a small bias and an additional jitter of 2-4 ns.

Publication Metadata

Authors: Jorge Querol, Adriano Camps, Esteban Garbin Manfredini, Ricardo Piriz
Venue: 2018 European Frequency and Time Forum (EFTF) (2018)
Research Areas: RFI Mitigation & GNSS Security, GNSS & Positioning
DOI: 10.1109/eftf.2018.8409021

Antena Bi-banda con conformación de dos haces simultáneos para sistemas GNSS-R

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

Abstract & Overview

This research contribution by Raúl Onrubia Ibáñez, Daniel Pascual Biosca, Jorge Querol, Adriano Joséé Camps Carmona (2018), published in XXXIII Simposium Nacional de la Unión Cientı́fica Internacional de, investigates “Antena Bi-banda con conformación de dos haces simultáneos para sistemas GNSS-R” within the domains of JCAS & Earth Observation, GNSS & Positioning. 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: Raúl Onrubia Ibáñez, Daniel Pascual Biosca, Jorge Querol, Adriano Joséé Camps Carmona
Venue: XXXIII Simposium Nacional de la Unión Cientı́fica Internacional de (2018)
Research Areas: JCAS & Earth Observation, GNSS & Positioning

Determination of sea correlation time at L-Band with airborne reflected new GNSS signals

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

Abstract & Overview

The maximum coherent integration time of GNSS reflected (GNSS-R) signals over sea depends on the sea state, as well as on the geometry formed by the receiver, the GNSS satellite and the reflection point. In this paper, real data obtained with a dedicated airborne instrument named MALYGNSS (Multi-band Airborne L-Band reflectometrY with GNSS) is used to acquire GPS L1 C/A and L2C, and Galileo E1OS signals. The direct signals are used as a reference to detect any phase shift due to data bits changes and the presence of a residual Doppler frequency. These phase transitions are removed in the reflected signals, and coherent correlations of different lengths are performed in order to study sea correlation time.

Publication Metadata

Authors: D. Pascual, R. Onrubia, Jorge Querol, J. Castellvi-Esturi, H. Park, A. Camps
Venue: IGARSS 2018-2018 IEEE International Geoscience and Remote Sensing Symposium (2018)
Research Areas: GNSS & Positioning, AI & Neuromorphic SatCom
DOI: 10.1109/igarss.2018.8518552

Generic simulator for conical scanning microwave radiometers

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

Abstract & Overview

This work describes a software tool developed for ESA within the project BIBLOS-2 (BuIlding BLOcks for earth observation mission performance simulator) to model typical conical scanning microwave radiometers in a generic Earth Observation mission. It consists of functional modules: Geometry, Scene Generator, Instrument, and Level 1 data generation modules. This structure follows the architecture for generic Earth Observation mission simulator study, ARCHEO-E2E (ARCHitecture of Earth Observation). The improvement in the BIBLOS-2 Passive Microwave is developing the Radio Frequency Interferences (RFI) generation and mitigation functionality. The developed simulation modules will be provided soon via the BIBLOS web page (https://gmv-biblos.gmv.com/). In this paper, the functions of the BIBLOS-2 passive microwave are described module by module, including the RFI generation/mitigation examples.

Publication Metadata

Authors: H. Park, A. Camps, Jorge Querol, K. Szczepankiewicz, C. De Negueruela, W. Oryszczak, L. Soto, R. Kedzierawski, F. E. Aleman Roda
Venue: 2018 IEEE 15th Specialist Meeting on Microwave Radiometry and Remote (2018)
Research Areas: JCAS & Earth Observation
DOI: 10.1109/microrad.2018.8430699

Preliminary altimetry results of the MALYGNSS instrument in the HUMIT project

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

Abstract & Overview

In order to provide high resolution soil moisture maps, the Institut Cartografic i Geológic de Catalunya (ICGC) in colab-oration with Universitat Politecnica de Catalunya are planing to deploy the3Cat-3 picosatellite, which aims to estimate soil moisture from space using Global Navigation Satellite Systems - Reflectometry (GNSS-R) and to downscale it using data fusion with a multi-spectral camera. As a proof of concept, a field campaign is being carried out in Lleida, Catalunya. MALYGNSS is a GNSS reflectometer flying as an opportunity sensor that will validate the main reflectometer of the project: the CORTO instrument.

Publication Metadata

Authors: R. Onrubia, D. Pascual, Jorge Querol, J. Castellvi-Esturi, J. Corbera, H. Park, A. Camps
Venue: IGARSS 2018-2018 IEEE International Geoscience and Remote Sensing Symposium (2018)
Research Areas: JCAS & Earth Observation, GNSS & Positioning
DOI: 10.1109/igarss.2018.8518636

RFI analysis and mitigation in airborne GNSS-R campaign

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

Abstract & Overview

Radio-Frequency Interference (RFI) is one of the most concerning topics in Global Navigation Satellite Systems (GNSS) and GNSS - Reflectometry (GNSS-R) because any undesired signal present at the antenna can corrupt the received signal and the eventual geophysical measurements. The purpose of this paper is two-fold. First, an RFI analysis is performed to the raw data obtained from an airborne dual-band GNSS reflectometer. Finally, the Front-End GNSS Interference eXcisor (FENIX) mitigation algorithm is applied to the raw data, and then the Signal-to-Noise Ratio (SNR) improvement at the Delay-Doppler Map (DDM) is obtained. From the analysis of one of the datasets, two RFI signals were detected and characterized. Moreover, FENIX output signal was revealed to be much cleaner than before. The mean SNR improvement with coherent DDMs of 1 ms is 0.72 dB, whereas the SNR improvement increases to 1.49 dB when considering 50 incoherent averages. This improvement represents a reduction in the geophysical parameter estimation uncertainty.

Publication Metadata

Authors: Jorge Querol, R. Onrubia, D. Pascual, J. Castellvi-Esturi, H. Park, A. Camps
Venue: IGARSS 2018-2018 IEEE International Geoscience and Remote Sensing Symposium (2018)
Research Areas: JCAS & Earth Observation, RFI Mitigation & GNSS Security, GNSS & Positioning, AI & Neuromorphic SatCom
DOI: 10.1109/igarss.2018.8518827

Spaceborne GNSS-R end-to-end simulator: Topography and vegetation effects

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

Abstract & Overview

As the TDS-1 and CYGNSS spaceborne GNSS-R missions progress, a large number of Delay-Doppler Maps (DDM) is being collected, from the land scattered as well as from the ocean. Based on those data, the feasibility study on the retrieval of land geophysical parameters such as soil moisture and vegetation is being studied. This work presents the E2E simulator that generates the synthesized DDM reflected over land. For the efficient development, the existing simulator for ocean scattering has been upgraded to accommodate the specific functionalities for land scattering: topography, surface roughness, vegetation effects, in addition to surface soil moisture, obviously. The developed end-to-end (E2E) simulator is used to conceive the retrieval algorithms and assess their performance. In this work, the upgraded items are described and illustrated with some simulation results.

Publication Metadata

Authors: H. Park, A. Camps, D. Pascual, Jorge Querol, R. Onrubia
Venue: IGARSS 2018-2018 IEEE International Geoscience and Remote Sensing Symposium (2018)
Research Areas: JCAS & Earth Observation, GNSS & Positioning
DOI: 10.1109/igarss.2018.8517790

A radio-frequency interference detector for GNSS navigation and GNSS-reflectometry applications

Sun, 23 Jul 2017 00:00:00 +0000

Abstract & Overview

This paper presents a real-time Radio-Frequency Interference (RFI) detection and monitoring system designed for Global Navigation Satellite Systems (GNSS) navigation and GNSS-Reflectometry (GNSS-R) receivers operating at L-band, evaluating detection sensitivity against continuous-wave, swept-chirp, and pulsed interference sources.

Publication Metadata

Authors: Jorge Querol, Raul Onrubia, Daniel Pascual, Hyuk Park, Adriano Camps
Venue: 2017 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) (2017)
Research Areas: JCAS & Earth Observation, RFI Mitigation & GNSS Security, GNSS & Positioning
DOI: 10.1109/IGARSS.2017.8127965

Beamformer characterization of the MIR instrument: The microwave interferometric reflectometer

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

Abstract & Overview

Global Navigation Satellite Systems - Reflectometry (GNSS-R) has opened promising results for remote sensing applications. The broadcast of new signals with wider bandwidth provides an opportunity to increase the performance of GNSS reflectometry applications. The Microwave Interferometric Reflectometer (MIR) is an instrument being developed to compare different GNSS-R techniques, namely the conventional and interferometric ones, and assess the capabilities of these new signals and bands of the GPS and Galileo systems. This work describes the tests to validate the beamforming system.

Publication Metadata

Authors: R. Onrubia, D. Pascual, Jorge Querol, H. Park, A. Camps
Venue: 2017 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) (2017)
Research Areas: Beamforming & MIMO
DOI: 10.1109/igarss.2017.8128132

Calibration of GNSS-R receivers with PRN signal injection: Methodology and validation with the microwave interferometric reflectometer (MIR)

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

Abstract & Overview

The demonstration of the feasibility of navigation signals signals for remote sensing has lead to a significant increase of new GNSS-R instruments in the recent years. Despite of the type instrument, the observables are based on the cross-correlations of the received GNSS signals. Most of these instruments combine the signals received by multiple chains, in such a way that they need a proper calibration. This work proposes a calibration procedure for GNSS-R instruments by using a calibration signal with similar statistics to the GNSS signals. The method is tested and validated with the Microwave Interferometric Reflectometer (MIR) instrument, which contains 152 chains. The test results will be presented at the conference.

Publication Metadata

Authors: D. Pascual, R. Onrubia, Jorge Querol, H. Park, A. Camps
Venue: 2017 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) (2017)
Research Areas: JCAS & Earth Observation, GNSS & Positioning
DOI: 10.1109/igarss.2017.8128131

Real-time Pre-correlation Anti-jamming System for Civilian GNSS Receivers

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

Abstract & Overview

Global Navigation Satellite Systems (GNSS) have become a key technology that enables numerous location and navigation applications, thanks to the 24/7 worldwide availability of their signals, and the positioning accuracy that can be reached with them. However, GNSS have also some weaknesses, and the most relevant is that their signals reach the Earth’s surface with very low power. This makes them quite vulnerable to the effect of Radio-Frequency Interference (RFI), and particularly to intentional jamming, which degrades, or even disrupts, the performance of the receivers. This problem is particularly threatening for those critical GNSS-enabled applications that trust on the integrity and continuity of GNSS signals, whose reliability may be committed. Such liability/security-critical civilian applications include autonomous aerial/terrestrial navigation, automatic rail signaling, geo-localized toll/insurance payments, or network synchronization among others. Moreover, RFI is also troublesome for derived GNSS applications such as GNSS-Reflectometry (GNSS-R) where GNSS signals are used as signals of opportunity in a multi-static radar configuration for Earth observation purposes. A number of mitigation solutions have been proposed to increase the continuity of GNSS signals in the presence of jamming signals. Regarding the structure of a GNSS system, the mitigation process can be performed at different stages: antenna, front-end, pre-correlation, post-correlation, or measurement. Common antenna solutions can provide spatiotemporal selectivity, which can reach interference rejection ration higher than 40 dB, but this is only achieved in static scenarios. On the contrary, pre-correlation techniques work at signal level, between antenna and GNSS correlators, providing interference selectivity in time, frequency, statistical, or other sub-space signal domains, which can mitigate jamming signals regardless the scenario dynamics. Moreover, pre-correlation techniques usually have a high computational burden in order to achieve high performance with interference rejection ratios higher than 30 dB. However, last generation Field Programmable Gate Arrays (FPGA) can overcome this drawback, and they even enable real-time pre-correlation anti-jamming solutions. The Front-End GNSS Interference eXcisor (FENIX) is a GNSS anti-jamming technology based on the patented combination of statistical interference detection, and a multiresolution time-frequency blanking algorithm for jamming mitigation in DSSS-based multi-constellation GNSS receivers [1]. The main goal of FENIX is to increase the C/N0 in the presence of interference signals, thus improving the continuity of GNSS services. Moreover, the mitigation algorithm has been designed to be DSSS-based multi-constellation, frequency independent (i.e. it works at L1 and L2, L5…), and it is capable of mitigating almost all kinds of jamming signals. A general description of the major building blocks of FENIX was first presented in [2]. This work aims at showing the implementation and first results of a real-time L1/L2 GPS/Galileo lite version of FENIX (FENIX-lite) tested using commercial jammers and GNSS receivers. The FENIX-lite demonstrator has been implemented using a two Software Defined Radio (SDR) model USRP B200mini, the first covers the GPS L1 C/A and Galileo E1 OS services, whereas the second does the same with the GPS L2C signal. The SDR front-ends are tuned to the L1 and L2 bands, and the FENIX interference detection and mitigation algorithm is running in real-time in both FPGA. The FENIX algorithm detects the interference signal using a statistical domain analysis based on normality tests, while the samples containing most part of interference power signal are excised in the time-frequency space computed using the Multiresolution Fourier Transform (MFT). The use of the MFT allows to mitigate almost of kinds of jamming signals since it maximized the projection of the interference signal in the transformed domain as demonstrated in [3]. In order to evaluate the improvement in the continuity of the GNSS signals, the degradation of the SNR with and without the FENIX-lite is compared using jammers at different bands and commercial GNSS receivers. [1] J. Querol, and A. Camps, “System and method for detecting and eliminating radio frequency interferences in real time,” U.S. Patent Application 15 222 036, issued date July 28, 2016. [2] J. Querol, E. M. Julian, R. Onrubia, A. Alonso-Arroyo, D. Pascual and A. Camps, “Preliminary results of FENIX: Front-End GNSS Interference eXcisor,” 2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Beijing, 2016, pp. 5627-5630. [3] J. Querol; R. Onrubia; A. Alonso-Arroyo; D. Pascual; H. Park; A. Camps, “Performance Assessment of Time-Frequency RFI Mitigation Techniques in Microwave Radiometry,” in IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, in press.

Publication Metadata

Authors: Jorge Querol, Adriano Camps
Venue: Proceedings of the 30th International Technical Meeting of The Satellite (2017)
Research Areas: RFI Mitigation & GNSS Security, GNSS & Positioning
DOI: 10.33012/2017.15304

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

Assessment of DME/TACAN RFI mitigation techniques in GNSS-R

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

Abstract & Overview

Global Navigation Satellite Systems Reflectometry (GNSSR) is now being recognized as a powerfull tool for remote sensing. With the addition of new frequency bands and codes, it is possible to increase the resolution and accuracy of the measurements. GPS L5 and Galileo E5 bands are becoming popular because of the open codes, with wider bandwidths than the L1 band ones. However, these bands are shared with two radio navigation systems (DME and TACAN) that transmit with high powers and might interfere them. The use of mitigation techniques may affect the power of the received signal, which will affect the GNSS-R observables. This work presents several the mitigation techniques, and evaluates the performance and impact of the selected ones for ESA’s GEROS experiment onboard the International Space Station.

Publication Metadata

Authors: R. Onrubia, Jorge Querol, D. Pascual, H. Park, A. Alonso-Arroyo, A. Camps
Venue: 2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) (2016)
Research Areas: JCAS & Earth Observation, RFI Mitigation & GNSS Security, GNSS & Positioning
DOI: 10.1109/igarss.2016.7730255

Can we measure vegetation water content and vegetation opacity at L-band with a single GPS receiver?

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

Abstract & Overview

This work shows a technique to estimate the vegetation opacity and infer the vegetation water content using a single GPS receiver located under the vegetation layer being analyzed. It is based on the measurement of the received signal power when the GPS satellite is at the zenith, and when the GPS satellite is with an elevation of 30 degrees. Assuming a horizontally stratified vegetation layer, the attenuation on the GPS signal due to vegetation doubles at 30° elevation angle compared to the zenith. This attenuation is directly related to the vegetation opacity. Then, the vegetation opacity is related to the vegetation water content by a linear parameter. Initial results relating the measured GPS signal power to canopy parameters obtained from hemispheric photos are shown.

Publication Metadata

Authors: A. Alonso-Arroyo, Jorge Querol, A. Camps, R. Onrubia, H. Park, D. Pascual
Venue: 2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) (2016)
Research Areas: GNSS & Positioning
DOI: 10.1109/igarss.2016.7729512

Comparison of real-time time-frequency RFI mitigation techniques in microwave radiometry

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

Abstract & Overview

Radio-Frequency Interference (RFI) is a well-known problem for Microwave Radiometers (MWR). A number of RFI mitigation techniques have been studied to deal with RFI from the receiver’s side. In this study, a comparison in terms of performance among several real-time time-frequency RFI mitigation techniques is presented. Time-frequency techniques are of high importance because the vast majority of RFI signals are well-localized in the time-frequency space. The five techniques compared under study are: Pulse Blanking (PB), Frequency Blanking (FB), Spectrogram Blanking (SB), Wavelet Denoising (WD), and Multiresolution Fourier Transform (MFT). Results show that the best performance depends on the particular type of RFI, and occurs when the transform basis is similar to the RFI, that is, the projection on that particular basis is maximized. However, there is not a single technique that is effective for all RFI signals, and future approaches may be based on a combination of several techniques.

Publication Metadata

Authors: Jorge Querol, R. Onrubia, D. Pascual, A. Alonso-Arroyo, H. Park, A. Camps
Venue: 2016 14th Specialist Meeting on Microwave Radiometry and Remote Sensing (2016)
Research Areas: JCAS & Earth Observation, RFI Mitigation & GNSS Security
DOI: 10.1109/microrad.2016.7530506

First Delay Doppler Maps obtained with the Microwave Inteferometric Reflectometer (MIR)

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

Abstract & Overview

This work presents the first Delay Doppler Maps (DDMs) obtained with the Microwave Interferometric Reflectometer (MIR) airborne instrument. MIR is a GNSS Reflectometer (GNSS-R) which uses the conventional (cGNSS-R) and interferometric (iGNSS-R) techniques for ocean and land observation. It computes real-time sample-to-sample complex DDMs with averaging and alignment, of up to 4 simultaneous GPS/Galileo satellites at the L1/E1, and L5/E5a bands. Satellites are tracked with high directivity antennas with beam steering. The MIR instrument is designed to validate and compare both GNSS-R techniques with the new available signals, with special focus in the GEROS-ISS payload, and to contribute to the development of geophysical retrieval algorithms.

Publication Metadata

Authors: D. Pascual, R. Onrubia, Jorge Querol, A. Alonso-Arroyo, H. Park, A. Camps
Venue: 2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) (2016)
Research Areas: GNSS & Positioning, AI & Neuromorphic SatCom
DOI: 10.1109/igarss.2016.7729514

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

Preliminary results of FENIX: front-end GNSS interference eXcisor

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

Abstract & Overview

The number of applications based on Global Navigation Satellite Systems (GNSS) has been increasing in last years. In the passive remote sensing field, GNSS-Reflectometry (GNSS-R) systems have been revealed as cost-effective solutions to retrieve a number of geophysical parameters. However, GNSS-based devices are prone to suffer from Radio-Frequency Interference (RFI) effects due to the extreme low power of involved signals. This paper shows the preliminary results of the Front-End GNSS Interference eXcisor (FENIX), a system designed to mitigate the RFI problem in GNSS-based systems. FENIX is composed by two stages: the RF stage and the SP stage. The former conditions the signal from the antenna, throw the SP stage, and to the receiver; and the latter excises the RFI from the GNSS signal combining thresholding with the Multiresolution Fourier Transform (MFT). Preliminary results show that FENIX can mitigate up to 30 dB a chirp RFI signal generated from commercial jammers.

Publication Metadata

Authors: Jorge Querol, E. M. Julian, R. Onrubia, A. Alonso-Arroyo, D. Pascual, A. Camps
Venue: 2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) (2016)
Research Areas: RFI Mitigation & GNSS Security, GNSS & Positioning
DOI: 10.1109/igarss.2016.7730470

Advances in the MIR instrument: Integration, control subsystem and analysis of the flight dynamics for beamsteering purposes

Thu, 01 Jan 2015 00:00:00 +0000

Abstract & Overview

The MIR (Microwave Interferometric Reflectometer) is a new dual frequency Global Navigation Satellite Systems Reflectometry (GNSS-R) instrument that implements conventional and interferometric reflectometry, both with GPS and Galileo signals. This paper presents the instrument development progress, mainly in the control part, where a methodology to determine how much the platform attitude will affect the beam steering and a satellite selection algorithm have been developed.

Publication Metadata

Authors: R. Onrubia, L. Garrucho, D. Pascual, H. Park, Jorge Querol, A. Alonso-Arroyo, A. Camps
Venue: 2015 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) (2015)
Research Areas: Beamforming & MIMO
DOI: 10.1109/igarss.2015.7326895

Assessment of back-end RFI mitigation techniques in passive remote sensing

Thu, 01 Jan 2015 00:00:00 +0000

Abstract & Overview

Radio-Frequency Interference (RFI) is a growing problem specially for those systems that work with low power signals such as passive remote sensing instruments. Consequently, RFI mitigation techniques are currently under development. This works aims at evaluating back-end mitigation algorithms in terms of their probability of detection and mitigation performance. Results show that Wavelet Denoising (WD), and Multiresolution Fourier Transform (MFT) are the best techniques in most scenarios, specially for GNSS-based instruments.

Publication Metadata

Authors: Jorge Querol, A. Alonso-Arroyo, R. Onrubia, D. Pascual, A. Camps
Venue: 2015 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) (2015)
Research Areas: JCAS & Earth Observation, RFI Mitigation & GNSS Security
DOI: 10.1109/igarss.2015.7326890

Two dedicated soil moisture experiments using the scatterometric properties of GNSS-reflectometry

Thu, 01 Jan 2015 00:00:00 +0000

Abstract & Overview

This work presents two field campaigns performed between December 2014 and June 2015 in order to better understand the behavior of Global Navigation Satellite Systems (GNSS) reflected signals over land. The instruments used in both field campaigns are briefly introduced. One of them is focused on circular polarization, whereas the other is focused on linear polarization (horizontal and vertical). In one field experiment there is evidence of multipath due to the antenna performance. A method to mitigate it is proposed in this work. Finally, some preliminary soil moisture estimations using vertical polarization are shown.

Publication Metadata

Authors: A. Alonso-Arroyo, S. Torrecilla, Jorge Querol, A. Camps, D. Pascual, H. Park, R. Onrubia
Venue: 2015 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) (2015)
Research Areas: JCAS & Earth Observation, GNSS & Positioning
DOI: 10.1109/igarss.2015.7326682

A stratospheric balloon GNSS-R experiment: The 3 Cat-2 project in DLR/SNSB BEXUS

Wed, 01 Jan 2014 00:00:00 +0000

Abstract & Overview

Universitat Politècnica de Catalunya (UPC) - BarcelonaTech Remote Sensing Laboratory focus on the development of breakthrough concepts. The3Cat-2 mission is on the synergy of GNSS reflectometry and the CubeSat concept. Scientifically valuable mission data will improve our understanding on the Earth’s environment. In particular, ocean currents need further investigation because of the spatio-temporal evolution of the mesoscale phenomena. The spacecraft development work includes two stratospheric flights in the frame of the REXUS/BEXUS programme coordinated by the European Space Agency (ESA). Coherent and incoherent scattering of Earth-reflected GNSS signals as sensed by the P(Y) & C/A ReflectOmeter (PYCARO) payload will be evaluated using the main state-of-the art Global Navigation Satellite Systems Reflectometry (GNSS-R) methodologies. Future spaceborne activities could take advantage of it, including the GNSS REflectometry, Radio Occultation and Scatterometry on-board International Space Station (GEROS-ISS) experiment.

Publication Metadata

Authors: H. Carreno-Luengo, A. Camps, Jorge Querol, G. Forte, R. Onrubia, R. Diez
Venue: 2014 IEEE Geoscience and Remote Sensing Symposium (2014)
Research Areas: JCAS & Earth Observation, GNSS & Positioning
DOI: 10.1109/igarss.2014.6947268

Review of GNSS-R instruments and tools developed at the Universitat Politecnica de Catalunya-Barcelona tech

Wed, 01 Jan 2014 00:00:00 +0000

Abstract & Overview

Reflectometry using Global Navigation Satellite System’s signals of opportunity (GNSS-R) was originally conceived in the early 90s for mesoscale altimetry, and since then, many studies have shown its applicability to other remote sensing applications. In 2002, the Remote Sensing Lab at the Universitat Politècnica de Catalunya started working in Global Navigation Satellite Reflectometry (GNSS-R) to perform a more accurate correction of the sea state when retrieving sea surface salinity from L-band microwave radiometer data (e.g. SMOS). During these 12 years, the lab has developed ground-based, airborne, balloon, and spaceborne GNSS-R payloads for a number of different applications. This paper provides an overview of the families of instruments, and the design choices made.

Publication Metadata

Authors: A. Camps, J. F. Marchan-Hernandez, X. Bosch-Lluis, N. Rodriguez-Alvarez, I. Ramos-Perez, E. Valencia, J. M. Tarongíi, H. Park, H. Carreno-Luengo, A. Alonso-Arroyo, D. Pascual, R. Onrubia, G. Forte, Jorge Querol
Venue: 2014 IEEE Geoscience and Remote Sensing Symposium (2014)
Research Areas: JCAS & Earth Observation, GNSS & Positioning
DOI: 10.1109/igarss.2014.6947318

Study of RFI signals in protected GNSS bands generated by common electronic devices: Effects on GNSS-R measurements

Wed, 01 Jan 2014 00:00:00 +0000

Abstract & Overview

RFI (Radio Frequency Interference) signals are a threat for GNSS-R (Global Navigation Satellite Systems - Reflectometry) due to the very low power of the navigation signals. Interference signals coming from computers or high-speed buses may affect GNSS-R measurements introducing a bias or even corrupting them completely. These RFI may be in-band or near-band and can desensitize GNSS and GNSS-R receivers. A number of techniques are currently under development to mitigate the effect of RFI signals.

Publication Metadata

Authors: Jorge Querol, G. F. Forte, A. Camps
Venue: 2014 IEEE Geoscience and Remote Sensing Symposium (2014)
Research Areas: JCAS & Earth Observation, RFI Mitigation & GNSS Security, GNSS & Positioning
DOI: 10.1109/igarss.2014.6947375

Digital back-end for RFI detection and mitigation in earth observation

Tue, 01 Jan 2013 00:00:00 +0000

Abstract & Overview

A powerful real time Radio-frequency interference (RFI) mitigation back-end system is presented in this work. The interfering signals are estimated by using the wavelet transform to utilize its effective denoising capability. The estimated RFI signals are then subtracted from the total received signal, and ultimately the RFI-mitigated signal is obtained. Here, the hardware implementation and the system tests are demonstrated, showing sinusoid, chirp, and PRN interference mitigation under different Interference to Noise Ratios (INRs).

Publication Metadata

Authors: G.F. Forte, Jorge Querol, H. Park, A. Camps
Venue: 2013 IEEE International Geoscience and Remote Sensing Symposium-IGARSS (2013)
Research Areas: RFI Mitigation & GNSS Security
DOI: 10.1109/igarss.2013.6723177