Description du sujet de thèse

The tidal increase of communications among humans and objects has made actual the concept of pervasive computing through its natural accomplishment, the Internet of Things (IoT). Triggered by such a revolutionary networking paradigm, a huge number of concurrent technological solutions have been proposed. Specifically, Low Power Wide Area Networks (LPWAN) technologies will play a key role in the development of smart agriculture solutions, as well as in many other applications, including Smart Grid, Environmental Monitoring, and Emergency Management, among others. However, the abovementioned terrestrial technologies fail to provide global connectivity. Terrestrial networks are also highly vulnerable in case of natural disasters or terrorist attacks. Instead, satellite access networks, and, in particular, large-scale Low-Earth Orbit (LEO) satellite constellations have shown their potential to extend terrestrial networks to address the above issues. In this context, satellites can be leveraged to support a world-wide expansion of the promising IoT market. Recently, the combination of satellite networks and LPWAN technologies has been proposed as a promising hybrid networking architecture [1,2]. Indeed, backhauling satellite networks interconnecting LPWAN gateways provides both reachability in remote areas and redundancy in case of service disruption of the ground network [3]. Among LPWAN technologies, Narrow Band IoT (NB-IoT) has been designed by 3GPP to handle IoT traffic on the licensed spectrum, and its deployment at large scale will be facilitated with its inherent interoperability with 5G and 6G networks. However, to cope with the variation of both the Doppler shift and propagation delay inherent to the communication with constellations of LEO satellites travelling at high speed over the monitored zone, the 3GPP mandates the equipment of low power devices with a GNSS receiver. This is done for letting device being aware of their position and able to synchronize with LEO satellites broadcasting their ephemerides orbital parameters. Remarkably, the GNSS is an unwanted source of power consumption, and makes this architecture non-resilient in case of GNSS service failures, outages, etc. Some ideas have been developed to design a GNSS-free synchronization scheme for NB-IoT communications to constellations of LEO satellites with discontinuous coverage [4,5]. In this context, the research envisaged by this PhD program includes: (i) design and implementation of a ground experimental emulation of a LEO satellite equipped with NB-IoT capabilities able to mimic the Doppler curve models; (ii) performance evaluation of the strategies [4,5]; (iii) investigate time and frequency pre-compensation to enable low power communication with LEO satellites and to make NB-IoT a viable solution for reliable IoT applications.
[1] M. R. Palattella, N. Accettura. “Enabling Internet of Everything Everywhere: LPWAN with satellite backhaul.” GIIS 2018, Thessaloniki, Greece.
[2] J. Fraire, S. Céspedes, N. Accettura. “Direct-To-Satellite IoT - A Survey of the State of the Art and Future Research Perspectives: Backhauling the IoT Through LEO Satellites.” ADHOC-NOW 2019, Luxembourg.
[3] Z. Zhou, M. Afhamisis, M. R. Palattella, N. Accettura, P. Berthou. “Pervasive LPWAN connectivity through LEO Satellites: trading off reliability, throughput, latency, and energy efficiency.” In Low-Power Wide-Area Networks: Opportunities, Challenges, Risks and Threats, Springer, 978-3-031-32934-0
[4] Z. Zhou, N. Accettura, R. Prévost, P. Berthou. “Lightweight synchronization to NB-IoT enabled LEO Satellites through Doppler prediction.” IEEE WiMob 2023, Montreal, Canada
[5] Z. Zhou, N. Accettura, P. Berthou. “A wake-up strategy enabling GNSS-free NB-IoT links to sparse LEO satellite constellations.” IEEE Internet of Things Journal, vol. 12, no. 12, pp. 21996-22011, 2025, doi: 10.1109/JIOT.2025.3551911

Contexte de travail

The Laboratory for Analysis and Architectures of Systems is a CNRS unit with activities in a wide range of fields. The PhD program will be carried out within the SARA team (Services et Architectures pour les Réseaux Avancés), under the supervision of Nicola Accettura (nicola.accettura@laas.fr), as part of the ANR PEPR DONUTS project.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.