6G-NTN | Dr. Jorge Querol

TDD in 5G LEO Satellite Networks: A Comparative Study of Guard-Period Strategies and Frame Durations

Tue, 20 Oct 2026 00:00:00 +0000

Abstract & Overview

This paper presents a comparative study of guard-period (GP) sizing rules (Worst-RTT, Adaptive Per-UE, and Minimum-RTT) and Extraordinary Downlink (xDL) guard-period reuse across 10–182 ms frame durations for Time-Division Duplex (TDD) in 5G NR Low Earth Orbit (LEO) satellite networks, supported by the European Space Agency (ESA) ARTES 4.0 Project CREST-5G.

Publication Metadata

Authors: Madyan Alsenwi, Jorge Querol, Eva Lagunas
Venue: Ka and Broadband Communications Conference 2026 (2026)
Research Areas: 6G-NTN, Satellite Communications

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

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

Abstract & Overview

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

Publication Metadata

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

6G Nanosatellites to Orbit the Edge: Performance Characterization of a COTS-Based 5G NR UE

Tue, 02 Jun 2026 00:00:00 +0000

Abstract & Overview

This research contribution by Jacob Gummesson Atroshi, Türker Yilmaz, Srikanth Goli, Jorge Querol et al. (2026), published in Joint European Conference on Networks and Communications & 6G Summit (EuCNC/6G Summit), investigates “6G Nanosatellites to Orbit the Edge: Performance Characterization of a COTS-Based 5G NR UE” within the domains of 6G-NTN, Satellite Communications. 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: Jacob Gummesson Atroshi, Türker Yilmaz, Srikanth Goli, Jorge Querol, Symeon Chatzinotas
Venue: Joint European Conference on Networks and Communications & 6G Summit (EuCNC/6G Summit) (2026)
Research Areas: 6G-NTN, Satellite Communications
DOI: 10.1109/eucnc/6gsummit68295.2026.11577574

Satellite and Mobile Network Operator Cooperation Models for Efficient Handover in 6G-TN-NTN

Tue, 02 Jun 2026 00:00:00 +0000

Abstract & Overview

Cooperation between satellite and mobile network operators enables the integration of non-terrestrial satellite networks (NTNs) with terrestrial networks (TNs), allowing users to seamlessly switch from Mobile Network Operators (MNOs) to Satellite Network Operators (SNOs) in areas with limited MNO coverage or during high-speed travel. However, mobility issues, such as connection failures, the ping-pong effect, and high interruption times, can occur during these transitions. This paper examines various cooperation models, including roaming and handover protocols, and proposes key enhancements to these models to reduce service interruption time. It also discusses the use of machine learning (ML) techniques to reduce the above mobility issue and increase the success rate of cooperation among network operators.

Publication Metadata

Authors: Tedros Salih Abdu, Eva Lagunas, Flor Ortiz, Jorge Querol, Joel Grotz, Marcele O. K. Mendonça, Ons Aouedi, Symeon Chatzinotas
Venue: The 15th EASN International Conference on “Innovation in Aviation & Space Towards Sustainability Today & Tomorrow” (2026)
Research Areas: 6G-NTN, Satellite Communications
DOI: 10.3390/engproc2026133187

Channel Extrapolation based Downlink Precoding using 5G NR Uplink SRS in LEO Satellite

Sun, 24 May 2026 00:00:00 +0000

Abstract & Overview

This research contribution by Ashish Kumar Meshram, Sumit Kumar, Ashok Bandi, Jorge Querol et al. (2026), published in International Conference on Communications, investigates “Channel Extrapolation based Downlink Precoding using 5G NR Uplink SRS in LEO Satellite” within the domains of 6G-NTN, Satellite Communications, 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: Ashish Kumar Meshram, Sumit Kumar, Ashok Bandi, Jorge Querol, Stefano Andrenacci, Symeon Chatzinotas
Venue: International Conference on Communications (2026)
Research Areas: 6G-NTN, Satellite Communications, Beamforming & MIMO
DOI: 10.1109/icc59461.2026.11587772

When 5G NTN Meets GNSS: Tracking GNSS Signals under Overlaid 5G Waveforms

Sun, 24 May 2026 00:00:00 +0000

Abstract & Overview

Global Navigation Satellite Systems (GNSS) provide the backbone of Positioning, Navigation, and Timing (PNT) but remain vulnerable to interference. Low Earth Orbit (LEO) constellations within Fifth-Generation (5G) Non-Terrestrial Networks (NTN) can enhance resilience by jointly supporting communication and navigation. This paper presents the first quantitative analysis of GNSS tracking and navigation message demodulation under a hybrid waveform where a low-power Direct-Sequence Spread Spectrum (DSSS) component is overlaid on an Orthogonal Frequency-Division Multiplexing (OFDM) 5G downlink. We evaluate a minimally modified GNSS receiver that tracks a legacy Global Positioning System (GPS) L1 Coarse/Acquisition (C/A) overlay aligned with 5G frames while treating the 5G waveform as structured interference. Using Monte Carlo simulations under realistic LEO Doppler dynamics, we analyze the Bit Error Rate (BER) of GPS L1 C/A navigation bits and the subframe decoding probability versus Signalto- Interference-plus-Noise Ratio (SINR) for multiple Signalto- Interference Ratios (SIR) and dynamic classes. Results show reliable demodulation across wide SINR ranges for low and medium dynamics, whereas high dynamics impose strict lock limits. These findings confirm the feasibility of Joint Communication and Positioning (JCAP) using a near-legacy GNSS chipset with minimal receiver modifications.

Publication Metadata

Authors: Idir Edjekouane, Alejandro Gonzalez-Garrido, Jorge Querol, Symeon Chatzinotas
Venue: International Conference on Communications (2026)
Research Areas: 6G-NTN, GNSS & Positioning, AI & Neuromorphic SatCom
DOI: 10.1109/icc59461.2026.11587695

Lightweight Deep Learning-Aided LDPC Decoding for 5G NR UAV Communications

Mon, 18 May 2026 00:00:00 +0000

Abstract & Overview

This research contribution by Carla E. García, Jorge Querol, Mario R. Camana, Symeon Chatzinotas (2026), published in IEEE Transactions on Aerospace and Electronic Systems, investigates “Lightweight Deep Learning-Aided LDPC Decoding for 5G NR UAV Communications” within the domains of 6G-NTN, 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: Carla E. García, Jorge Querol, Mario R. Camana, Symeon Chatzinotas
Venue: IEEE Transactions on Aerospace and Electronic Systems (2026)
Research Areas: 6G-NTN, AI & Neuromorphic SatCom
DOI: 10.1109/infocom59046.2026.11571367

Collaborative Multi-Band Multi-Orbit 6G Satellites with Multi-Connectivity: The Roles of Carrier Aggregation and Dual Connectivity

Fri, 01 May 2026 00:00:00 +0000

Abstract & Overview

Non-terrestrial networks (NTNs), particularly satellites, are increasingly being recognized as vital components beyond complementing terrestrial networks (TNs) in unified TN-NTN 6G systems. However, satellites operate independently in their orbits with single frequency bands, facing performance limitations that hinder their ability to satisfy diverse requirements. This has driven interest in transitioning from singleband single-orbit to multi-band multi-orbit (MBMO) systems, leveraging spectral and orbital diversities. This article emphasizes the significance of MBMO and presents multi-connectivity (MC) as an effective approach enabling collaboration across bands and orbits. We focus on carrier aggregation (CA) and dual connectivity (DC), two essential enablers of MC at different levels of the 3GPP protocol stack. We discuss their principles, benefits, and usage scenarios along with two case studies. A Ku-Ka inter-band CA case study demonstrated gains in throughput and reliability, ensuring service continuity under adverse weather conditions for a multi-band geostationary orbit (GEO) system. A multi-orbit DC between GEO and low Earth orbit (LEO) shows how DC addresses LEO satellite mobility challenges through seamless handovers. We also outline some open issues that require further study and advancement.

Publication Metadata

Authors: Mohammed Al-Ansi, Jorge Querol, Eva Lagunas, Madyan Alsenwi, Symeon Chatzinotas
Venue: IEEE Communications Magazine (2026)
Research Areas: 6G-NTN, Satellite Communications
DOI: 10.1109/mcom.001.2500337
Open Access Repository: ORBiLu – University of Luxembourg

High-Accuracy Ranging in 5G Non-Terrestrial Networks: Receiver Architectures and Interference Analysis

Fri, 01 May 2026 00:00:00 +0000

Abstract & Overview

This research contribution by Idir Edjekouane, Alejandro González-Garrido, Jorge Querol, José A. del Peral-Rosado et al. (2026), published in IEEE Transactions on Vehicular Technology, investigates “High-Accuracy Ranging in 5G Non-Terrestrial Networks: Receiver Architectures and Interference Analysis” within the domains of 6G-NTN, RFI Mitigation & GNSS Security, 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: Idir Edjekouane, Alejandro González-Garrido, Jorge Querol, José A. del Peral-Rosado, Ivan Lapin
Venue: IEEE Transactions on Vehicular Technology (2026)
Research Areas: 6G-NTN, RFI Mitigation & GNSS Security, GNSS & Positioning
DOI: 10.1109/navitec202669090.2026.11692531

Holographic Mimo for Next-Generation Nonterrestrial Networks: Motivation, Opportunities, and Challenges

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

Abstract & Overview

In this article, we propose the integration of the holographic multiple-input multiple-output (HMIMO) as a transformative solution for next-generation nonterrestrial networks (NTNs), addressing key challenges, such as high hardware costs, launch expenses, and energy inefficiency. Traditional NTNs are constrained by the financial and operational limitations posed by bulky and costly antenna systems, alongside the complexities of maintaining effective communications in space. HMIMO offers a novel approach utilizing compact and lightweight arrays of densely packed radiating elements with real-time reconfiguration capabilities, thus capable of optimizing system performance under dynamic conditions such as varying orbital dynamics and Doppler shifts. By replacing conventional antenna systems with HMIMO, the number of required radio-frequency (RF) chains can be cut to roughly one-tenth while achieving about threefold lower power consumption and an order-of-magnitude decrease in hardware cost. Thus, manufacturing and launch expenses can be substantially reduced, paving the way for more streamlined and cost-effective NTN deployments. This advancement holds significant potential to democratize space communications, making them accessible to a broader range of stakeholders, including smaller nations and commercial enterprises. Moreover, the inherent capabilities of HMIMO in enhancing energy efficiency, scalability, and adaptability position this technology as a key enabler of new use cases and sustainable satellite operations.

Publication Metadata

Authors: Giovanni Iacovelli, Chandan Kumar Sheemar, Wali Ullah Khan, Asad Mahmood, George C. Alexandropoulos, Jorge Querol, Symeon Chatzinotas
Venue: IEEE Vehicular Technology Magazine (2026)
Research Areas: 6G-NTN, Beamforming & MIMO
DOI: 10.1109/mvt.2026.3673016

Intelligent Handover Management for Hybrid TN–NTN Mobility in 6G Architectures

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

Abstract & Overview

This research contribution by Ons Aouedi, Tedros Salih Abdu, Kha Hung NGUYEN, Eva Lagunas et al. (2026), published in Open Repository and Bibliography (University of Luxembourg), investigates “Intelligent Handover Management for Hybrid TN–NTN Mobility in 6G Architectures” 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: Ons Aouedi, Tedros Salih Abdu, Kha Hung NGUYEN, Eva Lagunas, Jorge Querol, Joël Grotz
Venue: Open Repository and Bibliography (University of Luxembourg) (2026)
Research Areas: 6G-NTN
Open Access Repository: ORBiLu – University of Luxembourg

Mirage Detector: A Reliable Multiuser Preamble Detector for 6G-NTN

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

Abstract & Overview

Accessing non-terrestrial networks (NTN) via existing 4G/5G handheld devices without positioning information presents significant challenges in achieving precise synchronization between a gNodeB and hundreds of users dispersed across an NTN cell. While terrestrial communication standards limit the relative delay between the center and edge of coverage to 200 km, multilayered NTN can introduce user-specific delay variation spanning thousands of kilometers. To address this challenge, we reeingeer the receiver’s Random Access (RA) preamble detector to achieve robust detection and Transmission Arrival (TA) estimation of scattered users with unknown but deterministic differential delays. The proposed Physical layer algorithm, termedMiragedetector, aligns with current 3GPP NTN standardization efforts and is forward/backward-compatible with future/earlier releases.Miragedetector leverages a dynamicStridingmechanism for multiple hypothesis testing, making it resilient to high false alarm rates caused by signals arriving beyond their nominal duration.Miragealso efficiently supports multiuser detection, enabling rapid resynchronization during frequent handovers—approximately twice per minute per Connected UE—while minimizing computational load of the transceivers. Extensive simulations results validate the advantage of the proposedMiragedetector that enables reliable multilayer connectivity for hundreds of legacy devices within the access occasion periodicity, without requiring hardware upgrades or any self-localization capability.

Publication Metadata

Authors: Ali Georganaki, Jorge Querol, Thang X. Vu, Symeon Chatzinotas
Venue: IEEE Open Journal of the Communications Society (2026)
Research Areas: 6G-NTN
DOI: 10.1109/ojcoms.2026.3679839
Open Access Repository: ORBiLu – University of Luxembourg

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

Survey on Beyond Diagonal RIS-Enabled 6G Wireless Networks: Fundamentals, Recent Advances, and Challenges

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

Abstract & Overview

Beyond Diagonal Reconfigurable Intelligent Surfaces (BD-RIS) represent a groundbreaking innovation in sixth-generation (6G) wireless networks, enabling unprecedented control over wireless propagation environments compared to conventional diagonal RIS (D-RIS). This survey provides a comprehensive analysis of BD-RIS, detailing its architectures, operational principles, and mathematical modeling while highlighting its performance benefits. BD-RIS classifications, including single-connected, fully-connected, and group-connected architectures, and their reflective, transmissive, hybrid, and multi-sector operating modes are examined. Recent advances in BD-RIS-enabled 6G networks are reviewed, focusing on critical areas such as channel estimation, sum-rate and spectral efficiency optimization, energy efficiency enhancement, and security. The survey identifies fundamental challenges in BD-RIS research, including hardware design limitations, adaptive channel estimation, and the impact of non-ideal hardware effects. Future research directions for BD-RIS are proposed, emphasizing the integration of artificial intelligence and machine learning (AI/ML), joint optimization of communication and sensing, and enhanced physical layer security (PLS). This study concludes by underscoring BD-RIS’s transformative potential to redefine 6G wireless networks, offering valuable insights and lessons for future research and development.

Publication Metadata

Authors: Wali Ullah Khan, Chandan Kumar Sheemar, Manzoor Ahmed, Marco Di Renzo, Syed Tariq Shah, Asad Mahmood, Eva Lagunas, Jorge Querol, Symeon Chatzinotas, Zhu Han
Venue: IEEE Open Journal of the Communications Society (2026)
Research Areas: 6G-NTN
DOI: 10.1109/ojcoms.2026.3734637
Open Access Repository: ORBiLu – University of Luxembourg

A Machine Learning-Based Receiver for Mitigating Nonlinear Distortion in OFDM Systems for 5G

Mon, 07 Jul 2025 00:00:00 +0000

Abstract & Overview

This work introduces a convolutional neural network (CNN)-based receiver designed for channel estimation, equalization, and symbol demapping in orthogonal frequency-division multiplexing (OFDM) systems. The proposed receiver is specifically developed to mitigate nonlinear distortions, particularly under low input back-off (IBO), thereby markedly enhancing signal quality and energy efficiency. By significantly reducing the bit error rate (BER) and outperforming traditional methods, the CNN-based receiver establishes itself as a highly robust solution for next-generation communication technologies. These advancements are pivotal for the development of reliable and efficient communication networks, particularly in the context of the fifth generation (5G) and beyond. Furthermore, this work contributes to the integration of terrestrial and non-terrestrial networks by addressing critical challenges in mitigating nonlinear distortions in satellite and hybrid communication systems using AI-driven techniques.

Publication Metadata

Authors: Marcele O. K. Mendonça, Francisco J. Martín Vega, Geoffrey Eappen, Carla E. García, Abuzar B. M. Adam, Jorge Querol, Beatriz Soret, Symeon Chatzinotas
Venue: IEEE International Mediterranean Conference on Communications and Networking (MeditCom) (2025)
Research Areas: 6G-NTN, AI & Neuromorphic SatCom
DOI: 10.1109/meditcom64437.2025.11104481
Open Access Repository: ORBiLu – University of Luxembourg

Statistical Acquisition of DVB-S2X Signal for Positioning in LEONTN

Tue, 10 Jun 2025 00:00:00 +0000

Abstract & Overview

Low Earth Orbit (LEO) mega-constellations are revolutionizing global communication by delivering high-speed internet and supporting a wide range of services. Beyond communication, recent studies have shown that LEO satellites can also provide Positioning, Navigation, and Timing (PNT) services. Leveraging existing LEO Non-terrestrial-network (NTN) for dual-purpose applications has garnered significant attention as a future-oriented approach. This paper investigates the feasibility of re-purposing a well-established satellite communication protocol, Digital Video Broadcasting Second Generation Satellite Extensions (DVB-S2X), for positioning applications within LEONTN. This paper analyses the statistical acquisition performance similar to the Global Navigation Satellite System (GNSS) to evaluate the potential of DVB-S2X for positioning estimation. This analysis can provide a baseline for trade-offs for communication protocol selection when developing a sustainable integrated navigation and communication (Nav-Comm) system within LEONTN.

Publication Metadata

Authors: Harshal More, Idir Edjekouane, Ernestina Cianca, Mauro De Sanctis, Jorge Querol, Ottavio M. Picchi, Francesco Menzione
Venue: International Conference on Localization and GNSS (2025)
Research Areas: 6G-NTN, Satellite Communications, GNSS & Positioning
DOI: 10.1109/icl-gnss65520.2025.11046183
Open Access Repository: ORBiLu – University of Luxembourg

Secrecy Rate Maximization for 6G Reconfigurable Holographic Surfaces Assisted Systems

Mon, 03 Mar 2025 00:00:00 +0000

Abstract & Overview

Reconfigurable holographic surfaces (RHS) have emerged as a transformative material technology, enabling dynamic control of electromagnetic waves to generate versatile holographic beam patterns. This paper addresses the problem of secrecy rate maximization for an RHS-assisted systems by joint designing the digital beamforming, artificial noise (AN), and the analog holographic beamforming. However, such a problem results to be non-convex and challenging. Therefore, to solve it, a novel alternating optimization algorithm based on the majorization-maximization (MM) framework for RHS-assisted systems is proposed, which rely on surrogate functions to facilitate efficient and reliable optimization. In the proposed approach, digital beamforming design ensures directed signal power toward the legitimate user while minimizing leakage to the unintended receiver. The AN generation method projects noise into the null space of the legitimate user channel, aligning it with the unintended receiver channel to degrade its signal quality. Finally, the holographic beamforming weights are optimized to refine the wavefronts for enhanced secrecy rate performance Simulation results validate the effectiveness of the proposed framework, demonstrating significant improvements in secrecy rate compared to the benchmark method.

Publication Metadata

Authors: Chandan Kumar Sheemar, Wali Ullah Khan, Marco Di Renzo, Asad Mahmood, Jorge Querol, Symeon Chatzinotas
Venue: arXiv (Cornell University) (2025)
Research Areas: 6G-NTN, Beamforming & MIMO
DOI: 10.48550/arxiv.2503.01741

Enhanced demodulator for 5G NTN using spatio-temporal attention convolutional autoencoder and Akida Brainchip SNN

Sat, 01 Feb 2025 00:00:00 +0000

Abstract & Overview

This paper presents a novel approach to overcoming challenges in 5G and 6G mobile satellite systems (MSS) in Low Earth Orbit (LEO), focusing on Non-Line-of-Sight (NLOS) issues in 5G Non-Terrestrial Networks (NTN) that connect directly with handheld devices. We utilize a Convolutional Neural Network (CNN) with a Spatio-Temporal Attention Network (STAN) autoencoder, which is then converted into a Spiking Neural Network (SNN) using Brainchip Akida’s Meta TF Software Framework. This integration of neuromorphic processing aims to enhance energy efficiency, reduce computational demands, and increase data transmission rates, optimizing Channel State Information (CSI) in compliance with 3GPP standards. Our STAN-CNN-SNN architecture achieves a 85% reduction in computational requirements, leading to decrease in power consumption, and increase in data rates within the C-Band spectrum. Simulations with LEO satellite MSS parameters demonstrate significant advancements in communication systems. The numerical results demonstrates substantial computational reductions with minimal capacity trade-offs.

Publication Metadata

Authors: Swetha Varadarajulu, Marcele O. K. Mendonça, Geoffrey Eappen, Jorge Querol, Symeon Chatzinotas
Venue: IET conference proceedings. (2025)
Research Areas: 6G-NTN, AI & Neuromorphic SatCom
DOI: 10.1049/icp.2024.4619
Open Access Repository: ORBiLu – University of Luxembourg

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

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

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

Abstract & Overview

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

Publication Metadata

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

A Vision, Survey, and Roadmap Toward Space Communications in the 6G and Beyond Era

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

Abstract & Overview

Satellite communications (SatComs) have recently been through a renaissance, both technologically and entrepreneurially. Ambitious plans have already come into fruition with the operation of low-Earth orbit (LEO) constellations including thousands of satellites and supported by state of the art but proprietary technologies, such as active antenna arrays and intersatellite links (ISLs). In this context, this article aims to provide a forward-looking vision of use cases and a deep dive into technological enablers that will be prominent in space communications beyond 2030. In parallel, it motivates how open standards can play a role in delivering affordable communication services in space. Starting from the 5G plans for nonterrestrial networks, we provide a survey and roadmap toward artificial intelligence (AI)-supported satellite systems, space-enabled quantum networks, and joint communications and positioning (JCAP) for space missions and interplanetary exploration.

Publication Metadata

Authors: Konstantinos Ntontin, Eva Lagunas, Jorge Querol, Junaid ur Rehman, Joël Grotz, Symeon Chatzinotas, Björn Ottersten
Venue: Proceedings of the IEEE (2025)
Research Areas: 6G-NTN
DOI: 10.1109/jproc.2024.3512934
Open Access Repository: ORBiLu – University of Luxembourg

Reduced Complexity Initial Synchronization for 5G NR Multibeam LEO-Based Non-Terrestrial Networks

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

Abstract & Overview

This paper presents a computationally efficient technique to mitigate the overall Carrier Frequency Offset (CFO) impairment introduced by the User Equipment (UE) crystal oscillator imperfection and the Doppler effect introduced by the satellite and UE movement. We assume steerable multibeam regenerative Low Earth Orbit (LEO) satellite-based 5G New Radio (NR) Non-Terrestrial Networks (NTN) under trajectory uncertainty and beam-pointing errors. The UE and the satellite do not require any prior information on the satellite ephemeris or UE location to achieve initial synchronization. The novelty of our method lies in exploiting the instantaneous satellite state vector for Doppler Pre-Compensation (DPC) to each beam of the LEO satellite relative to its Beam Center (BC). The UE then performs post-compensation to address the residual frequency offset by employing aggregated 5G New Radio (NR) Primary Synchronization Signal (PSS), followed by PSS detection, offering two-fold search space reduction during initial synchronization. We provide practical design parameters for the proposed algorithm to ensure that UE can efficiently perform initial synchronization by evaluating approximate bounds on the spot beam radius along with the No-Benefit Region (NBR) bounds of DPC. We conducted extensive simulations to assess the performance of the S- and Ka-bands under the NTN channel model and validated it with the corresponding analytical expressions conditioned on satellite trajectory uncertainty and beam-pointing error. Our method ensures that the probability of PSS detection remains above 90% while maintaining a false alarm rate of 1% at a Signal-to-Noise Ratio (SNR) as low as −6 (dB) if the standard deviation of the satellite trajectory and beam-pointing errors are within 5 (km) and 0.05°, respectively.

Publication Metadata

Authors: Ashish Kumar Meshram, Sumit Kumar, Jorge Querol, Stefano Andrenacci, Symeon Chatzinotas
Venue: IEEE Open Journal of the Communications Society (2025)
Research Areas: 6G-NTN, Satellite Communications, Beamforming & MIMO
DOI: 10.1109/ojcoms.2025.3543625
Open Access Repository: ORBiLu – University of Luxembourg

SMS2 – Sustainable Multi-functional Satellite Systems

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

FNR Luxembourg

Role: Principal Investigator (PI)
Funding: FNR-CORE (Luxembourg) · €787,000 (2025–2028)

Executive Summary

SMS2 (Sustainable Multi-functional Satellite Systems) investigates the co-design and coexistence of multi-functional payloads (communications, radar earth observation, and navigation) operating on shared hardware and spectrum on single satellite platforms.

Key Objectives & Contributions

Shared Spectrum & Hardware Coexistence: Development of joint waveform optimization algorithms allowing simultaneous communication and radar sensing without self-interference.
Spectrum Efficiency: Maximizing spectral utilization in L-band and S-band non-terrestrial networks.
Space Sustainability: Minimizing orbital footprint and energy consumption per satellite payload.

Project Details

Funding Agency: Luxembourg National Research Fund (FNR-CORE 2024)
Budget: €787,000
Duration: 2025 – 2028 (36 months)
Role: Principal Investigator (PI)
Host Institution: SnT – University of Luxembourg (6GSPACE Lab)

← Back to All 17 R&D Projects Portfolio

User Equivalent Range Error and Positioning Accuracy Analysis for ToA-Based Techniques Using PRS and SSB in 5G/6G NTN

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

Abstract & Overview

The integration of Non-Terrestrial Network (NTN) within the Fifth Generation (5G) and Sixth Generation (6G) ecosystem offers new opportunities for global Positioning, Navigation, and Timing (PNT) services, particularly in environments where Global Navigation Satellite System (GNSS) signals are obstructed or degraded. This work investigates the positioning performance of Time of Arrival (ToA)-based techniques using both Positioning Reference Signal (PRS) and Synchronization Signal Block (SSB) signals in 5G NTN scenarios. A comprehensive User Equivalent Range Error (UERE) model is developed, incorporating satellite, receiver, and propagation-related error sources across FR1 and FR2 frequency bands. The influence of satellite geometry is assessed through a Geometrical Dilution of Precision (GDOP) analysis, while a minimum satellite visibility evaluation quantifies the likelihood of observing at least four satellites above various elevation masks for representative LEO constellations at 600 km and 1200 km altitudes. Monte Carlo simulations quantify the impact of UERE on positioning accuracy, revealing that the 95th-percentile horizontal errors range from approximately 8 m to 26 m, depending on signal type, frequency band, and orbital altitude. The results demonstrate that ToA-based positioning using PRS can surpass typical urban GNSS-level accuracy, highlighting its potential in GNSS-challenged environments. In comparison, SSB-based positioning remains a viable alternative, offering reduced complexity at the cost of moderate accuracy trade-offs. The study offers a unified framework for understanding positioning accuracy in 5G/6G NTN, bridging UERE modeling, satellite visibility, and signal design considerations, and supporting the ongoing development of reliable global PNT services.

Publication Metadata

Authors: Idir Edjekouane, Alejandro González-Garrido, Jorge Querol, Symeon Chatzinotas
Venue: IEEE Open Journal of the Communications Society (2025)
Research Areas: 6G-NTN, GNSS & Positioning
DOI: 10.1109/ojcoms.2025.3623669
Open Access Repository: ORBiLu – University of Luxembourg

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

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

Abstract & Overview

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

Publication Metadata

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

Demonstration of Safe Electromagnetic Radiation Emitted by 5G Active Antenna Systems

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

Abstract & Overview

The careful planning and safe deployment of 5G technologies will bring enormous benefits to society and the economy. Higher frequency, beamforming, and small-cells are key technologies that will provide unmatched throughput and seamless connectivity to 5G users. Superficial knowledge of these technologies has raised concerns among the general public about the harmful effects of radiation. Several standardization bodies are active to put limits on the emissions which are based on a defined set of radiation measurement methodologies. However, due to the peculiarity of 5G such as dynamicity of the beams, network densification, Time Division Duplexing mode of operation, etc, using existing EMF measurement methods may provide inaccurate results. In this context, we discuss our experimental studies aimed towards the measurement of radiation caused by beam-based transmissions from a 5G base station equipped with an Active Antenna System(AAS). We elaborate on the shortcomings of current measurement methodologies and address several open questions. Next, we demonstrate that using user-specific downlink beamforming, not only better performance is achieved compared to non-beamformed downlink, but also the radiation in the vicinity of the intended user is significantly decreased. Further, we show that under weak reception conditions, an uplink transmission can cause significantly high radiation in the vicinity of the user equipment. We believe that our work will help in clearing several misleading concepts about the 5G EMF radiation effects. We conclude the work by providing guidelines to improve the methodology of EMF measurement by considering the spatiotemporal dynamicity of the 5G transmission.

Publication Metadata

Authors: Sumit Kumar, Chandan Kumar Sheemar, Abdelrahman Astro, Jorge Querol, Symeon Chatzinotas
Venue: arXiv preprint arXiv:2406.07910 (2024)
Research Areas: 6G-NTN, Beamforming & MIMO
DOI: 10.48550/arxiv.2406.07910

High-Resolution 5G Active Antenna Beam Pattern Measurement Using UAVs

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

Abstract & Overview

This paper presents a measurement methodology for obtaining a high-resolution beam pattern of 5G active antenna systems (AASs) using Unmanned Aerial Vehicles (UAVs). Beam pattern measurements are typically conducted in an anechoic chamber by placing the active antenna at the center and radiation pattern is measured at various angles. This approach is limited by the spatial constraints of the chamber and is time-consuming for obtaining high-resolution measurements. To address this problem, UAVs equipped with measurement sensors are proposed to fly around the antenna and do the measurement campaign. The beam pattern measurement campaign problem is formulated into a UAV path planning problem. Horizontal circular arcs at various elevation angles are defined on a sphere centered at the antenna and connected at their ends alternatively to define a reference path and transcribe it into a reference trajectory for the UAV. A chattering-free super-twisting controller is designed to accurately track this trajectory against unknown matched disturbances and model uncertainties. The proposed methodology is validated by an indoor experiment with a horn antenna set up to operate in the frequency range of a 5G AAS and create a stationary beam. A universal software radio peripheral is mounted on a UAV and programmed to measure the received signal strength indicator in real time and a high-resolution beam pattern is satisfactorily captured.

Publication Metadata

Authors: DMKK Venkateswara Rao, Sumit Kumar, Hamed Habibi, Jorge Querol, Symeon Chatzinotas, Holger Voos
Venue: 2024 International Conference on Unmanned Aircraft Systems (ICUAS) (2024)
Research Areas: 6G-NTN, Beamforming & MIMO
DOI: 10.1109/icuas60882.2024.10556877
Open Access Repository: ORBiLu – University of Luxembourg

Holographic MIMO for Next Generation Non-Terrestrial Networks: Motivation, Opportunities, and Challenges

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

Abstract & Overview

Publication Metadata

Authors: Giovanni Iacovelli, Chandan Kumar Sheemar, Wali Ullah Khan, Asad Mahmood, George C. Alexandropoulos, Jorge Querol, Symeon Chatzinotas
Venue: arXiv preprint arXiv:2411.10014 (2024)
Research Areas: 6G-NTN, Beamforming & MIMO
DOI: 10.48550/arXiv.2411.10014

Interference Analysis and Modeling of Positioning Reference Signals in 5G NTN

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

Abstract & Overview

The integration of Positioning, Navigation, and Timing (PNT) services within the 5G non-terrestrial networks (NTN) infrastructure is necessary to eliminate the need for a GNSS receiver in the user terminal. Using the positioning reference signal (PRS) in an NTN scenario presents significant challenges, such as interference analysis from the transmission of multiple PRS signals. This study provides a stochastic model for the interference generated by PRS transmissions in a 5G NTN scenario. This model has been derived empirically from a Monte Carlo simulator designed specifically for this purpose, showing that the distribution that best fits the interference is a Generalized Extreme Value (GEV) distribution. The parameters of this distribution are also modeled based on the PRS configuration. Therefore, a designer can use this model to evaluate the probability of encountering certain levels of interference.

Publication Metadata

Authors: Alejandro Gonzalez-Garrido, Jorge Querol, Henk Wymeersch, Symeon Chatzinotas
Venue: IEEE Open Journal of the Communications Society (2024)
Research Areas: 6G-NTN, RFI Mitigation & GNSS Security, GNSS & Positioning
DOI: 10.1109/ojcoms.2024.3503692
Open Access Repository: ORBiLu – University of Luxembourg

Interference analysis of Positioning Reference Signals in 5G NTN

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

Abstract & Overview

Accurate asset localization holds paramount importance across various industries, ranging from transportation management to search and rescue operations. In scenarios where traditional positioning equations cannot be adequately solved due to limited measurements obtained by the receiver, the utilization of Non-Terrestrial Networks (NTN) based on Low Earth Orbit (LEO) satellites can prove pivotal for precise positioning. The decision to employ NTN in lieu of conventional Global Navigation Satellite Systems (GNSS) is rooted in two key factors. Firstly, GNSS systems are susceptible to jamming and spoofing attacks, thereby compromising their reliability, where LEO satellites link budgets can benefit from a closer distances and the new mega constellations could offer more satellites in view than GNSS. Secondly, 5G service providers seek to reduce dependence on third-party services. Presently, the NTN operation necessitates a GNSS receiver within the User Equipment (UE), placing the service provider at the mercy of GNSS reliability. Consequently, when GNSS signals are unavailable in certain regions, NTN services are also rendered inaccessible.

Publication Metadata

Authors: Alejandro Gonzalez-Garrido, Jorge Querol, Henk Wymeersch, Symeon Chatzinotas
Venue: arXiv preprint arXiv:2401.09157 (2024)
Research Areas: 6G-NTN, RFI Mitigation & GNSS Security, GNSS & Positioning
DOI: 10.48550/arxiv.2401.09157

ML-based PBCH symbol detection and equalization for 5G Non-Terrestrial Networks

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

Abstract & Overview

This paper delves into the application of Machine Learning (ML) techniques in the realm of 5G Non-Terrestrial Networks (5G-NTN), particularly focusing on symbol detection and equalization for the Physical Broadcast Channel (PBCH). As 5G-NTN gains prominence within the 3GPP ecosystem, ML offers significant potential to enhance wireless communication performance. To investigate these possibilities, we present ML-based models trained with both synthetic and real data from a real 5G over-the-satellite testbed. Our analysis includes examining the performance of these models under various Signal-to-Noise Ratio (SNR) scenarios and evaluating their effectiveness in symbol enhancement and channel equalization tasks. The results highlight the ML performance in controlled settings and their adaptability to real-world challenges, shedding light on the potential benefits of the application of ML in 5G-NTN.

Publication Metadata

Authors: Inés Larráyoz-Arrigote, Marcele OK Mendonça, Alejandro Gonzalez-Garrido, Jevgenij Krivochiza, Sumit Kumar, Jorge Querol, Joel Grotz, Symeon Chatzinotas
Venue: 2024 IEEE International Mediterranean Conference on Communications (2024)
Research Areas: 6G-NTN
DOI: 10.1109/meditcom61057.2024.10621238
Open Access Repository: ORBiLu – University of Luxembourg

Towards 6G-UAV Disaster-Resilient Networks

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

Abstract & Overview

During natural disasters such as earthquakes, wildfires, hurricanes, landslides, tsunamis, CBRNE (chemical, medical, radiological, nuclear, or explosive) incidents, or terrorist threats, critical infrastructure can be severely damaged, with rescue workers facing immense obstacles. Providing help and reaching affected areas can be hazardous for human rescue personnel. To overcome this issue, 5G-enabled UAVs can play a significant role in deploying disaster-resilient networks. Such networks imply multiple challenges, including end-to-end communication reliability and low latency for UAV real-time control. In this paper, we focus on the end-to-end communication aspects of such networks. We present and implement our disaster-resilient network based on a combination of 5G-UAVs and satellite networks. We highlight the related challenges and define solutions based on 5G, Multi-access Edge Computing, UAVs, and dynamic geofencing. We integrate these solutions in an end-to-end network architecture and ultimately deploy it on a national joint 5G-satellite infrastructure to assess its performance. It performs well and demonstrates a recovery time of less than 30 seconds with $\mathbf{9 9 \%}$ network availability.

Publication Metadata

Authors: Youssouf DRIF, Abhishek BERA, Jorge Querol, Miguel Angel OLIVARES MENDEZ, Symeon CHATZINOTAS
Venue: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (2024)
Research Areas: 6G-NTN
DOI: 10.1109/pimrc59610.2024.10817298
Open Access Repository: ORBiLu – University of Luxembourg

5G NTN LEO based demonstrator using OpenAirInterface5G

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

Abstract & Overview

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

Publication Metadata

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

5G Positioning Reference Signal Configuration for Integrated Terrestrial/Non-Terrestrial Network Scenario

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

Abstract & Overview

The Fifth Generation (5G) New Radio offers a new Positioning, Navigation, and Timing (PNT) service with larger signal bandwidth and higher frequency carriers than previous generations, delivering more accurate measurements. This allows other vertical industries to benefit from this feature, opening up new possibilities. Furthermore, the 5G network includes Non-Terrestrial Network (NTN) elements such as Unmanned Aerial Vehicle (UAV), High-Altitude Platform Systems (HAPS), and satellites, which are gaining significant attention from the industry to allow for global communication. The future 6G aims to create a single network entity with multiple connectivity layers for all devices in all scenarios. Therefore, when combining both aspects of the 5G networks, the PNT service, and the NTN, there are several benefits such as: an independent and complete communication and navigation system under a single network, higher accuracy on the PNT solution than previous generation, global coverage for join navigation and communication, higher resilience on the positioning estimation, or new services offered. However, this is not free of challenges, as it is expected to achieve an accuracy, at least, similar to Global Navigation Satellite System (GNSS). One of the challenges is the multiplexing of the data and positioning service using a single infrastructure such a satellite. This paper has the purpose of analysing the effect in the accuracy of a delay estimator when a satellite constellation send a Positioning Reference Signal (PRS). Assuming that all satellites share the same frequency carrier and are synchronised between them. This 5G PRS main characteristic is its flexibility in terms of resource usage such as bandwidth, resource element density, symbols periodicity, a muting scheme, etc. This flexibility will be exploited in this paper to get a UE capable to estimate the Downlink Observed Time Difference of Arrival (DL-OTDoA) of the signal. Two challenges are present in this work, both are related to the characteristics of the RF channel between the Next Generation Base Station (gNB) and the User Equipment (UE): the first one is how the UE will cope with the high Doppler shift due to the high speed of the Low Earth Orbit (LEO) gNB increasing the Inter-Carrier Interference (ICI); and the second challenge is the effect of variable delay between OFDM symbols in the same slot and transmitter, increasing the effect of Intersymbol Interference (ISI). The contribution of the authors on this paper is the analysis of different PRS configuration that keeps a low interfere level between the moving gNBs. The result of this research highlight the impact that the length in number of subcarriers and number of OFDM symbol has in the accuracy of the delay estimation. It shows a trade-off in the constellation design, as a higher number of satellites in visibility also increase the ICI and ISI.

Publication Metadata

Authors: Alejandro Gonzalez-Garrido, Jorge Querol, Symeon Chatzinotas
Venue: 2023 IEEE/ION Position, Location and Navigation Symposium (PLANS) (2023)
Research Areas: 6G-NTN, GNSS & Positioning
DOI: 10.1109/plans53410.2023.10140024
Open Access Repository: ORBiLu – University of Luxembourg

Adaptive Timers and Buffer Optimization for Layer-2 Protocols in 5G Non-Terrestrial Networks

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

Abstract & Overview

Interest in the integration of Terrestrial Networks (TN) and Non-Terrestrial Networks (NTN); primarily satellites; has been rekindled due to the potential of NTN to provide ubiquitous coverage. Especially with the peculiar and flexible physical layer properties of 5G-NR, now direct access to 5G services through satellites could become possible. However, the large Round-Trip Delays (RTD) in NTNs require a re-evaluation of the design of RLC and PDCP layers timers (and associated buffers), in particular for the regenerative payload satellites which have limited computational resources, and hence need to be optimally utilized. Our aim in this work is to initiate a new line of research for emerging NTNs with limited resources from a higher-layer perspective. To this end, we propose a novel and efficient method for optimally designing the RLC and PDCP layers’ buffers and timers without the need for intensive computations. This approach is relevant for low-cost satellites, which have limited computational and energy resources. The simulation results show that the proposed methods can significantly improve the performance in terms of resource utilization and delays.

Publication Metadata

Authors: Chandan Kumar Sheemar, Sumit Kumar, Jorge Querol, Symeon Chatzinotas
Venue: 2023 International Conference on Software, Telecommunications and Computer (2023)
Research Areas: 6G-NTN
DOI: 10.23919/softcom58365.2023.10271637
Open Access Repository: ORBiLu – University of Luxembourg

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

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

Abstract & Overview

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

Publication Metadata

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

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

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

Abstract & Overview

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

Publication Metadata

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

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

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

Abstract & Overview

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

Publication Metadata

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

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

Localization as a key enabler of 6G wireless systems: A comprehensive survey and an outlook

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

Abstract & Overview

When fully implemented, sixth generation (6G) wireless systems will constitute intelligent wireless networks that enable not only ubiquitous communication but also high-accuracy localization services. They will be the driving force behind this transformation by introducing a new set of characteristics and service capabilities in which location will coexist with communication while sharing available resources. To that purpose, this survey investigates the envisioned applications and use cases of localization in future 6G wireless systems, while analyzing the impact of the major technology enablers. Afterwards, system models for millimeter wave, terahertz and visible light positioning that take into account both line-of-sight (LOS) and non-LOS channels are presented, while localization key performance indicators are revisited alongside mathematical definitions. Moreover, a detailed review of the state of the art conventional and learning-based localization techniques is conducted. Furthermore, the localization problem is formulated, the wireless system design is considered and the optimization of both is investigated. Finally, insights that arise from the presented analysis are summarized and used to highlight the most important future directions for localization in 6G wireless systems.

Publication Metadata

Authors: Stylianos E. Trevlakis, Alexandros-Apostolos A. Boulogeorgos, Dimitrios Pliatsios, Jorge Querol, Konstantinos Ntontin, Panagiotis Sarigiannidis, Symeon Chatzinotas, Marco Di Renzo
Venue: IEEE Open Journal of the Communications Society (2023)
Research Areas: 6G-NTN, GNSS & Positioning
DOI: 10.1109/ojcoms.2023.3324952
Open Access Repository: ORBiLu – University of Luxembourg

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

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

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

Abstract & Overview

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

Publication Metadata

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

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

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-terrestrial network testbeds for 5G and beyond

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

Abstract & Overview

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

Publication Metadata

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

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

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

Abstract & Overview

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

Publication Metadata

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

5G-NTN Prototyping and Experimentation Results

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

Abstract & Overview

This research contribution by Sumit Kumar, Jorge Querol, Symeon Chatzinotas, Marwan Hammouda et al. (2021), published in peer-reviewed journal, investigates “5G-NTN Prototyping and Experimentation Results” 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: Sumit Kumar, Jorge Querol, Symeon Chatzinotas, Marwan Hammouda, Thomas Heyn, Thomas Schlichter, Paulo Marques, Luis Pereira, Roberto Magueta, Florian Völk
Venue: Peer-Reviewed Journal Article (2021)
Research Areas: 6G-NTN

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

Random access procedure over non-terrestrial networks: From theory to practice

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

Abstract & Overview

Non-terrestrial Networks (NTNs) have become an appealing concept over the last few years and they are foreseen as a cornerstone for the next generations of mobile communication systems. Despite opening up new market opportunities and use cases for the future, the novel impairments caused by the signal propagation over the NTN channel, compromises several procedures of the current cellular standards. One of the first and most important procedures impacted is the random access (RA) procedure, which is mainly utilized for achieving uplink synchronization among users in several standards, such as the fourth and fifth generation of mobile communication (4 & 5G) and narrowband internet of things (NB-IoT). In this work, we analyse the challenges imposed by the considerably increased delay in the communication link on the RA procedure and propose new solutions to overcome those challenges. A trade-off analysis of various solutions is provided taking into account also the already existing ones in the literature. In order to broaden the scope of applicability, we keep the analysis general targeting 4G, 5G and NB-IoT systems since the RA procedure is quasi-identical among these technologies. Last but not least, we go one step further and validate our techniques in an experimental setup, consisting of a user and a base station implemented in open air interface (OAI), and an NTN channel implemented in hardware that emulates the signal propagation delay. The laboratory test-bed built in this work, not only enables us to validate various solutions, but also plays a crucial role in identifying novel challenges not previously treated in the literature. Finally, an important key performance indicator (KPI) of the RA procedure over NTN is shown, which is the time that a single user requires to establish a connection with the base station.

Publication Metadata

Authors: Oltjon Kodheli, Abdelrahman Astro, Jorge Querol, Mohammad Gholamian, Sumit Kumar, Nicola Maturo, Symeon Chatzinotas
Venue: IEEE Access (2021)
Research Areas: 6G-NTN
DOI: 10.1109/access.2021.3101291
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