Whitepaper Nº08·RAN·June 2026
5G From Orbit: NTN Engineering and the Direct-to-Device Race
How 3GPP took NR from terrestrial cells to orbit, and the two spectrum lanes racing to reach phones.
Abstract
5G needed no new waveform to work from orbit, only new clocks. The paper walks the engineering: the four things that break at orbital distances (timing, Doppler, HARQ, random access), the Rel-17 toolkit that fixes them, the Rel-19 on-board-gNB decision, and two commercial direct-to-device architectures.
Headline finding
541.46 ms — max round trip on a transparent GEO path (3GPP TR 38.821)
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This paper deepens one of our guides. If you want the shorter version first, read that.
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