ESA | 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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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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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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5GLEON – Radio Positioning Technologies for 5G Satellite Networks

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

European Space Agency

Role: Principal Investigator (PI)
Funding: European Space Agency (ESA) · €90,000 (2023–2025)

Executive Summary

5GLEON investigates Doppler-based and time-of-flight radio positioning methods using LEO 5G satellite constellations to provide resilient positioning, navigation, and timing (PNT) independent of GNSS.

Project Details

Funding Agency: European Space Agency (ESA)
Budget: €90,000
Duration: 2023 – 2025
Role: Principal Investigator (PI)

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NGSO-Sense – Prototype for Measuring NGSO Satellite Network Interference

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

European Space Agency

Role: Vice-Principal Investigator
Funding: European Space Agency (ESA) · €650,000 (2022–2025)

Executive Summary

NGSO-Sense designs a ground-based and airborne hardware sensor network to detect, locate, and measure radio frequency interference (RFI) across Non-Geostationary (NGSO) satellite bands.

Project Details

Funding Agency: European Space Agency (ESA)
Budget: €650,000
Duration: 2022 – 2025
Role: Vice-Principal Investigator

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PROSPECT – High Data Rate Proximity Communications for Space

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

European Space Agency

Role: Vice-Principal Investigator
Funding: European Space Agency (ESA) · €300,000 (2022–2024)

Executive Summary

PROSPECT develops high-capacity proximity wireless communication protocols for inter-satellite links, CubeSat swarms, and lunar rover-to-lander communications.

Project Details

Funding Agency: European Space Agency (ESA)
Budget: €300,000
Duration: 2022 – 2024
Role: Vice-Principal Investigator

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SPAICE – AI-Powered Satellite Signal Processing

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

European Space Agency

Role: Vice-Principal Investigator
Funding: European Space Agency (ESA) · €500,000 (2021–2025)

Executive Summary

SPAICE develops the Artificial Intelligence Satellite Telecommunications Testbed (AISTT), using commercial off-the-shelf (COTS) AI accelerators (such as neuromorphic and NPU hardware) for onboard beamforming, spectrum sharing, and interference detection.

Project Details

Funding Agency: European Space Agency (ESA)
Budget: €500,000
Duration: 2021 – 2025
Role: Vice-Principal Investigator

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