5G-NTN | Dr. Jorge Querol

CREST-5G – TDD & Guard-Period Optimization in 5G NR LEO Satellite Networks

Sun, 01 Jun 2025 00:00:00 +0000

European Space Agency

Role: Academic & PHY Lead (SnT – SIGCOM)
Funding: European Space Agency (ESA) ARTES 4.0 · Contract No. 4000147108/25/NL/RA (with OQ Technology SARL)

Executive Summary

CREST-5G is a European Space Agency (ESA) ARTES 4.0 research project conducted in collaboration with OQ Technology SARL (industrial & satellite prime, 5G NTN LEO operator) and SnT – University of Luxembourg (Academic & PHY Lead). The project investigates Time-Division Duplex (TDD) operation in 5G New Radio (NR) Low Earth Orbit (LEO) satellite networks, addressing the severe frame efficiency bottleneck caused by long two-way propagation Round-Trip Times (RTTs of 4–8 ms at 600 km altitude).

Key Technical Contributions

Guard-Period (GP) Sizing Strategies: Comparative evaluation of Worst-RTT (cell-edge), Adaptive Per-UE (RTT-based priority scheduling with per-user Timing Advance), and Minimum-RTT (nadir) guard-period configurations.
Extraordinary Downlink (xDL) Guard Reuse: Reclaiming the trailing DL-to-UL guard window during uplink wave propagation flight time (T_xDL ≤ RTT_min/2) to transmit additional downlink payload with zero satellite self-interference, boosting 10 ms frame efficiency up to 78.9%.
Multi-Frame Duration Trade-Offs: Joint evaluation of frame efficiency, DL/UL overlap fraction, and average 3GPP NR user data rate across 10, 20, 30, 40, and 182 ms frame durations in C-band (3.3–3.75 GHz).

Project Details & Outputs

Funding Agency: European Space Agency (ESA) ARTES 4.0 Programme (Contract No. 4000147108/25/NL/RA)
Consortium: OQ Technology SARL (Prime) & SnT – University of Luxembourg (SIGCOM / 6GSPACE Lab)
Featured Presentation: TDD in 5G LEO Satellite Networks: A Comparative Study of Guard-Period Strategies and Frame Durations (Ka and Broadband Communications Conference 2026, Milan – Slides PDF)

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COSMIC – Direct-to-Device Communications in Mobile Satellite Systems

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

FNR Luxembourg

Role: Principal Investigator (PI)
Funding: FNR-5G BRIDGES (Luxembourg) · €692,000 (2025–2028)

Executive Summary

COSMIC aims to enable direct-to-device (D2D) mobile satellite communications using C-band frequencies. The project encompasses radio channel characterization, custom terminal antenna prototyping, and over-the-satellite field demonstrations.

Key Objectives & Contributions

C-Band NTN Channel Modeling: Comprehensive propagation models for land-mobile satellite links in C-band.
Compact Terminal Antennas: Advanced antenna designs for handheld and IoT satellite terminals.
In-Orbit Field Demonstration: Live over-the-air validation connecting standard-based UE terminals via satellite.

Project Details

Funding Agency: FNR 5G BRIDGES (Luxembourg)
Budget: €692,000
Duration: 2025 – 2028 (36 months)
Role: Principal Investigator (PI)
Partner Companies: Industrial SatCom partners in Luxembourg

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5G-EMERGE – Satellite-Enhanced Edge Delivery

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

European Space Agency

Role: Principal Investigator (PI)
Funding: European Space Agency (ESA) · €460,000 (2024–2026)

Executive Summary

5G-EMERGE focuses on developing and demonstrating 5G Multicast and Broadcast Services (5MBS) over satellite non-terrestrial networks to deliver high-bandwidth content directly to edge nodes, CDN servers, and vehicular networks.

Key Objectives & Contributions

Satellite Edge Multicast: Integrating 5G core network multicast components with satellite payloads.
Cache Pre-positioning: Intelligent content delivery at the mobile edge using hybrid satellite-terrestrial architecture.
Real Field Prototyping: Testbed demonstration over geostationary and LEO satellite links.

Project Details

Funding Agency: European Space Agency (ESA)
Budget: €460,000
Duration: 2024 – 2026 (24 months)
Role: Principal Investigator (PI)

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5G-Nanosatellite – Integrated 5G UE for 3U CubeSat In-Orbit Demonstrator

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

ESA & Industry

Role: Principal Investigator (PI)
Funding: ESA + Altice (PT) · €542,000 (2024–2028)

Executive Summary

5G-Nanosatellite designs and builds an integrated 3GPP 5G NR User Equipment (UE) payload fitted into a 3U CubeSat form factor for live in-orbit validation of direct satellite-to-ground connectivity.

Project Details

Funding Agency: European Space Agency (ESA) & Altice Labs (Portugal)
Budget: €542,000
Duration: 2024 – 2028
Role: Principal Investigator (PI)

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ATLAS – Autonomous Systems for Land, Air and Space

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

FNR Luxembourg

Role: Principal Investigator (PI)
Funding: FNR-IPBG (Luxembourg) · €288,000 (2024–2029)

Executive Summary

ATLAS establishes a research program for multi-domain autonomous vehicles (UAVs, robots, satellites) using 5G non-terrestrial backhauling and edge AI for continuous operation in zero-trust environments.

Project Details

Funding Agency: FNR IPBG (Luxembourg)
Budget: €288,000
Duration: 2024 – 2029 (60 months)
Role: Principal Investigator (PI) & Main PhD Supervisor

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JuliaSatSim – Physical Layer Software Simulator in Julia

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

European Space Agency

Role: Principal Investigator (PI)
Funding: European Space Agency (ESA) · €340,000 (2024–2026)

Executive Summary

JuliaSatSim develops an open-source, high-performance physical layer software simulator written in Julia, supporting both 3GPP 5G NR NTN and DVB-S2X/RCS2 standards for European satellite infrastructure including IRIS².

Key Objectives & Contributions

High-Performance Simulation: Leveraging Julia’s just-in-time compilation for multi-gigabit link simulations.
Dual-Standard Support: Full PHY stack implementations of 3GPP Release 17/18 5G-NTN and DVB-S2X.
EU IRIS² Readiness: Providing open benchmarking tools for the upcoming European Sovereign Constellation.

Project Details

Funding Agency: European Space Agency (ESA ARTES)
Budget: €340,000
Duration: 2024 – 2026 (24 months)
Role: Principal Investigator (PI)

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TRANTOR – Sustainable 5G+ Evolution to Multiorbit and Multiband Networks

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

Horizon Europe

Role: Vice-Principal Investigator
Funding: Horizon Europe · €513,000 (2023–2025)

Executive Summary

TRANTOR develops multi-orbit, multi-band 5G/6G satellite architectures, introducing AI-driven resource allocation, satellite payload virtualization, and dynamic beam steering.

Project Details

Funding Agency: European Commission (Horizon Europe)
Budget: €513,000 (UniLux share)
Duration: 2023 – 2025
Role: Vice-Principal Investigator & General Chair of MOMBSAT 2025

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5GSpaceLab – 5G Space Communications Laboratory

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

Ministry of Economy

Role: Vice-Principal Investigator & Head of Lab
Funding: MECO-ISM (Luxembourg) · €600,000 (2020–2022)

Executive Summary

The 6GSPACE Lab (formerly 5G-SpaceLab) provides real-world experimental testbeds combining Software Defined Radios (SDRs), OpenAirInterface, satellite emulators, and RF chambers for testing 5G/6G NTN connectivity solutions.

Project Details

Funding Agency: Ministry of Economy (Luxembourg)
Budget: €600,000
Duration: 2020 – 2022
Role: Vice-Principal Investigator & Head of 6GSPACE Lab

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