Publications Journal article · Satellite IoT · 2026

Blind vs. Satellite-Detect Uplink in LEO Direct-to-Satellite IoT: An Analytical Threshold

Juan A. Fraire, Benoit Coeugnet, Oana Iova, André-Luc Beylot, and Vincent Deslandes

IEEE Transactions on Vehicular Technology, 2026

Abstract

Direct-to-Satellite IoT (DtS-IoT) networks deploy Low Earth Orbit (LEO) nanosatellites as fast-moving gateways for stationary, mobile, and vehicular sensor platforms. Their intermittent contact windows force a fundamental uplink design choice: transmit blindly and accept a non-zero loss probability, or first detect an overhead satellite via a downlink beacon. We derive a first-order analytical design rule for this trade-off and obtain a closed-form crossover constellation size that depends on only two dimensionless quantities: a beacon-overhead parameter, which combines the receive-to-transmit power ratio, the receiver duty cycle, the beacon period, and the uplink frame duration, and the single-satellite coverage fraction set by altitude and elevation mask. Below the threshold satellite-detect is more energy-efficient; above it, blind uplink wins. Walker Star propagation simulations locate the geometry-specific crossover and delimit the validity regime of the independent-coverage approximation, a parametric study quantifies how altitude, elevation mask, and duty cycle shift the threshold, and a lightweight ALOHA collision extension cross-checked by Monte Carlo assesses its sensitivity to offered load, including the pass-start traffic bursts that penalise beacon-triggered access. For baseline LoRa-over-satellite parameters (600 km altitude, 1% receiver duty cycle) the analytical threshold is about 220 satellites, while the propagated Walker Star crossover lies at about 120 satellites because structured constellations saturate coverage earlier than independent satellites. For 3GPP NB-IoT over non-terrestrial networks, under a chipset-averaged power ratio derived from public module datasheets, the threshold rises to about 540 satellites in the absence of acquisition overhead and falls below 200 once a synchronisation chain of 100 ms is charged to every delivery, identifying the constellation sizes beyond which a hypothetical lightweight-access mode would outperform today's acquisition-mandatory protocol.

Cite

DOI 10.1109/tvt.2026.3733173

BibTeX

@article{fraire2026blinddetect,
  author  = {Fraire, Juan A. and Coeugnet, Benoit and Iova, Oana and Beylot, Andr{\'e}-Luc and Deslandes, Vincent},
  title   = {Blind vs. Satellite-Detect Uplink in {LEO} Direct-to-Satellite {IoT}: An Analytical Threshold},
  journal = {IEEE Transactions on Vehicular Technology},
  year    = {2026},
  doi     = {10.1109/tvt.2026.3733173}
}

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