02 · RESEARCH TOPIC
Direct-to-Satellite IoT
A sensor on a farm or a buoy at sea can send its data straight to a satellite. I design the small constellations that serve such devices, and the radio access that lets low-cost, battery-powered hardware use them.
Large parts of the planet have no mobile coverage: oceans, deserts, farmland, forests. A sensor there can still send a few bytes at a time straight to a satellite overhead, using low-power radios such as LoRa that were designed for networks on the ground.
Keeping every point under a satellite at all times takes many satellites. If devices can wait for the next pass, a handful is enough, and the cost falls. I design these sparse constellations and the protocols that let thousands of devices share a short pass, much of it in the ANR project STEREO with Kinéis, a French operator of satellites for the Internet of Things, and French laboratories.
Results, with sources
- Nine satellites for the whole planet. If devices can go up to two hours without hearing from a satellite, the longest the LoRaWAN standard expects them to keep their timing, nine satellites in well-chosen orbits can reach them anywhere between 80° north and 80° south. Keeping every point in view at all times would take 88. This counts coverage only, for orbits at 700 km. Sparse Constellations, IEEE TAES 2022, §V-A, Fig. 6
- Waiting longer means fewer satellites. To serve every device across Africa, or across Europe, the designs in the study need 12 satellites if devices must hear from one at least once an hour, 4 if they can wait two hours, and 3 if they can wait about three. Sparse Constellations, IEEE TAES 2022, §V-B, Fig. 12
- Sensors that know the satellite's timetable. When devices use the satellite's predictable path to pick, moment by moment, the fastest radio setting that will still reach it, one pass can serve twice as many devices: from 250 to 500 in a simulated pass, with 60% of messages getting through on average. The comparison is with devices that always use the slowest, most robust setting. Uplink Policies, IEEE Access 2022, §V-A, Fig. 4
These are simulation results, under the assumptions set out in each paper.
Tools and projects
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FLoRaSat
An OMNeT++ simulator for end-to-end satellite IoT, with LoRa and LoRaWAN adapted to links with satellites. Its second version adds links between satellites.
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STEREO
Space-Terrestrial Integrated IoT: protocols that let low-cost devices reach satellites directly, with Inria, IRIT, LAAS, LIG and Kinéis.
Coordinator
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DORSAL-IoT
Downlink optimisation for robust direct-to-satellite IoT, with Universidad de Chile, UDP, UTEM and UFSC in Brazil.
Coordinating group member
Selected papers
- DORSAL: Downlink Optimization for Robust Direct-to-Satellite LoRaWAN IEEE Internet of Things Journal, 2026
- On the role of machine learning in satellite internet of things: A survey of techniques, challenges, and future directions Elsevier Computer Networks, 2025
- Space-Terrestrial Integrated Internet of Things: Challenges and Opportunities IEEE Communications Magazine, 2022
- Sparse Satellite Constellation Design for Global and Regional Direct-to-Satellite IoT Services IEEE Transactions on Aerospace and Electronic Systems, 2022
- Direct-To-Satellite IoT - A Survey of the State of the Art and Future Research Perspectives - Backhauling the IoT Through LEO Satellites International Conference on Ad-Hoc Networks and Wireless (ADHOC-NOW), 2019
People and partners
- Diego Maldonado, PhD at INSA Lyon and Inria (2026), co-supervised with Hervé Rivano: LoRa and LR-FHSS radio access for satellites.
- Gabriel Maiolini Capez, PhD at Politecnico di Torino (2026), co-supervised with Roberto Garello: sparse constellations for satellite IoT.
- Raydel Ortigueira, PhD at Universidad de Chile (2023), co-supervised with Sandra Céspedes: energy-efficient medium access, and devices that predict when a satellite is overhead.
- Alexander Ylnner Choquenaira Florez, PhD student at Inria: machine learning for satellite IoT, and FLoRaSat 2.
- Benoit Coeugnet, PhD student at IRIT and Inria with Kinéis, co-supervised with André-Luc Beylot: how devices should send when satellites are few.
- Hannah B. Pasandi, postdoc at Inria (2024–2025) with UC Berkeley: direct-to-device satellite communications.
IRIT · LAAS · LIG · Politecnico di Torino · Universidad de Chile · UC Berkeley
Funding
STIC-AmSud