https://jorge.querol.org/tags/tdd/TDDHugoBlox Kit (https://hugoblox.com)en-USSun, 01 Jun 2025 00:00:00 +0000https://jorge.querol.org/media/sharing.pnghttps://jorge.querol.org/tags/tdd/https://jorge.querol.org/project/crest-5g/Sun, 01 Jun 2025 00:00:00 +0000https://jorge.querol.org/project/crest-5g/<div class="mb-4"> <span class="badge-agency badge-esa">European Space Agency</span> </div> <p><strong>Role:</strong> Academic &amp; PHY Lead (SnT – SIGCOM)<br> <strong>Funding:</strong> European Space Agency (ESA) ARTES 4.0 · Contract No. 4000147108/25/NL/RA (with OQ Technology SARL)</p> <h3 id="executive-summary">Executive Summary</h3> <p><strong>CREST-5G</strong> is a European Space Agency (ESA) ARTES 4.0 research project conducted in collaboration with <strong>OQ Technology SARL</strong> (industrial &amp; satellite prime, 5G NTN LEO operator) and <strong>SnT – University of Luxembourg</strong> (Academic &amp; 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).</p> <h3 id="key-technical-contributions">Key Technical Contributions</h3> <ul> <li><strong>Guard-Period (GP) Sizing Strategies</strong>: 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.</li> <li><strong>Extraordinary Downlink (xDL) Guard Reuse</strong>: Reclaiming the trailing DL-to-UL guard window during uplink wave propagation flight time (<em>T</em>_xDL ≤ RTT_min/2) to transmit additional downlink payload with zero satellite self-interference, boosting 10 ms frame efficiency up to <strong>78.9%</strong>.</li> <li><strong>Multi-Frame Duration Trade-Offs</strong>: 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).</li> </ul> <h3 id="project-details--outputs">Project Details &amp; Outputs</h3> <ul> <li><strong>Funding Agency</strong>: European Space Agency (ESA) ARTES 4.0 Programme (Contract No. 4000147108/25/NL/RA)</li> <li><strong>Consortium</strong>: OQ Technology SARL (Prime) &amp; SnT – University of Luxembourg (SIGCOM / 6GSPACE Lab)</li> <li><strong>Featured Presentation</strong>: <a href="https://jorge.querol.org/uploads/talks/2026-10-ka-conf-tdd-leo.pdf">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)</a></li> </ul> <hr> <p><a href="https://jorge.querol.org/projects/">← Back to All 17 R&amp;D Projects Portfolio</a></p>