Post-Doctoral Research Visit F/M Robust Direct-to-Satellite Communication Using LoRaWAN

The Inria research centre in Lyon is the 9th Inria research centre, formally created in January 2022.  It brings together approximately 320 people in 19 research teams and research support services.

Its staff are distributed in Villeurbanne, Lyon Gerland, and Saint-Etienne.

The Lyon centre is active in the fields of software, distributed and high-performance computing, embedded systems, quantum computing and privacy in the digital world, but also in digital health and computational biology.

Every year Inria International Relations Department has a few postdoctoral positions in order to support Inria international collaborations.

This postdoctoral contract will have a duration of 12 to 24 months. The default start date is November 1st, 2026 and not later than January, 1st 2027. The postdoctoral fellow will be recruited by one of the Inria Centres in France, in this case, Inria Lyon, but it is recommended that the time is shared between France and the partner’s country, in this case the Universidade Federal de Santa Catarina in Brazil. Please note that the postdoctoral fellow has to start his/her contract being in France and that the visits have to respect Inria rules for missions.

Candidates for postdoctoral positions are recruited after the completion of their Ph.D. or a first postdoctoral period. To be eligible, candidates must have defended their Ph.D. no more than 3 years before the start date of the contract. As the start date will be between November 1, 2026 and January 1, 2027, the latest eligible Ph.D. defense date will vary accordingly (approximately between November 1, 2023 and January 1, 2024).

In order to encourage mobility, the postdoctoral position must take place in a scientific environment that is truly different from the one of the Ph.D. (and, if applicable, from the position held since the Ph.D.); particular attention is thus paid to French or international candidates who obtained their doctorate abroad.

Context

The emerging paradigm of Direct-to-Satellite Internet of Things (DtS-IoT) represents a significant advancement in linking terrestrial Low-Power Wide Area Network (LPWAN) technologies with Low-Earth Orbit (LEO) satellites. Through this new paradigm, IoT devices communicate using well-established terrestrial technologies such as LoRaWAN to transmit data directly to satellites, even without ground infrastructure. DtS-IoT enables efficient and seamless connectivity for global-scale applications such as international asset tracking, cross-border environmental monitoring, and global data collection and distribution. DtS-IoT also facilitates the development of applications in remote regions that would otherwise be challenging to cover with low-cost terrestrial IoT connectivity, like oceanic monitoring and remote agriculture.

While LPWAN technologies such as LoRaWAN suit DtS-IoT connectivity, existing prototypes and validations have predominantly emphasized data uplink communication (from end devices to satellites); however, downlink communication (from satellites to end devices) is of the utmost importance for ensuring robust data communication and user access to all the deployed end devices. This includes acknowledging successfully received uplink packets. Data flows from the Internet to ground devices through the LEO satellite network in these cases. Additionally, the downlink channel enables the LoRaWAN network and application servers to utilize a control channel to remotely configure end devices and operate actuators via the DtS-IoT network. This postdoc is focused on proposing and testing efficient medium access techniques within the DtS-IoT landscape, utilizing LEO satellite networks, and addressing the constraints of IoT communications in space.

Main Activities

1. State-of-the-Art and Problem Definition
• Review DtS-IoT systems with focus on random access protocols, LoRaWAN adaptations, and LEO constellation constraints.
• Identify key challenges: massive access scalability, collision dynamics, intermittent connectivity, and link budget variability.
2. MAC and Power Control Design
• Design a satellite-aware MAC protocol for LoRaWAN.
• Develop distributed transmit power control strategies adapting to satellite geometry and channel conditions.
• Explore cross-layer approaches coupling access decisions with PHY parameters (power, data rate).
3. Performance Evaluation 
• Define key metrics: delivery ratio, collision probability, latency, energy efficiency, fairness.
• Evaluate the proposed solutions in realistic LEO constellations and large device populations, across different constellation setups and traffic regimes.
• Benchmark against baseline schemes and analyze trade-offs between energy, reliability, and scalability. 
4. Dissemination
• Publish results in leading venues (e.g., IEEE ICC, GLOBECOM, IEEE Internet of Things Journal).

Bibliography

[1] LoRa Alliance, LoRaWAN 1.1 Specification, 2017.

[2] J. A. Fraire, O. Iova, and F. Valois, Space-Terrestrial Integrated Internet of Things: Challenges and Opportunities, in IEEE Communications Magazine, vol. 60, no. 12, pp. 64-70, 2022.

[3] F. A. Tondo, J. M. d. S. Sant’Ana, S. Montejo-Sánchez, O. L. A. López, S. Céspedes and R. D. Souza, "Nonorthogonal Multiple-Access Strategies for Direct-to-Satellite IoT Networks," in IEEE Transactions on Aerospace and Electronic Systems, vol. 61, no. 6, pp. 16267-16279, Dec. 2025.

[4] G. G. M. de Jesus, R. D. Souza, C. Montez and A. Hoeller, "LoRaWAN Adaptive Data Rate With Flexible Link Margin," in IEEE Internet of Things Journal, vol. 8, no. 7, pp. 6053-6061, 1 April1, 2021.

[5] C. Christelle, A. Guitton, O. Iova , and F. Valois, The Impact of Downlink Scheduling Policy on the Capacity of LoRaWAN, in IEEE Global Communications Conference (GLOBECOM), 2024.

[6] FLoRaSat simulator: https://gitlab.inria.fr/jfraire/florasat 

The ideal candidate for this postdoctoral position holds a PhD in Computer Science, Electrical or Telecommunications Engineering, or a related field, with a solid foundation in wireless networking, satellite communications, or LPWAN technologies such as LoRaWAN. Proficiency in programming — particularly in Python and C++ — is expected, along with experience in simulation environments (e.g., OMNeT++, NS-3) or in developing optimization and machine learning models. A firm grasp of mathematical modeling, performance evaluation, and network protocol design is highly desirable. Fluency in English is essential for effective collaboration and dissemination, while knowledge of French or Portuguese is advantageous but not required. The candidate should demonstrate a proactive, self-driven attitude and the ability to work independently and as part of an international, interdisciplinary team.

• Subsidized meals
• Partial reimbursement of public transport costs
• Leave: 7 weeks of annual leave + 10 extra days off due to RTT (statutory reduction in working hours) + possibility of exceptional leave (sick children, moving home, etc.)
• Possibility of teleworking (after 6 months of employment) and flexible organization of working hours
• Professional equipment available (videoconferencing, loan of computer equipment, etc.)
• Social, cultural and sports events and activities
• Access to vocational training
• Social security coverage

2927 € gross salary / month (social security included, income tax excluded)