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

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)

← Back to All 17 R&D Projects Portfolio