Multipath-based Cooperative Simultaneous Localization & Mapping through Machine Learning
The goal of this PhD is to explore the potential of machine learning (ML) tools for simultaneous localization and mapping (SLAM) applications, while leveraging multipath radio signals between cooperative wireless devices. The idea is to identify characteristic features of the propagation channels observed over multiple radio links, so as to jointly determine the relative positions of the mobile radio devices, as well as those of scattering objects present in their vicinity. Such radio features typically rely on the arrival times of multipath echos of the transmitted signals. The envisaged approach is expected to benefit from multipath correlation as the radio devices are moving, as well as from spatial diversity and information redundancy through multi-device cooperation. The developed solution will be evaluated on both real measurements collected with integrated Ultra Wideband devices in a reference indoor environment, and synthetic data generated with a Ray-Tracing simulator. Possible applications of this research concern group navigation in complex and/or unknown environments (incl. fleets of drones or robots, firefighters…).
New machine learning methods applied to side-channel attacks
Products secured by embedded cryptographic mechanisms may be vulnerable to side-channel attacks. Such attacks are based on the observation of some physique quantities measured during the device activity, whose variation may provoke information leakage and lead to a security flaw.
Today, such attacks are improved, even in presence of specific countermeasures, by deep learning based methods.
The goal of this thesis is go get familiarity with semi-supervised and self-supervised Learning state-of-the-art and adapt promising methods to the context of the side-channel attacks, in order to improve performances of the attacks in very complex scenarios. A particular attention will be given to attacks against secure implementations of post-quantum cryptographic algorithms.
Cryptographic security of RISC-V processor enclaves with CHERI
CHERI (Capability Hardware Enhanced RISC Instructions) is a solution for securing the processor against spatial and temporal memory leaks by transforming any pointer into a capability that clearly defines the access limits to the data or instructions addressed.
In this thesis, we propose to enrich CHERI and its control-flow integrity capabilities on a RISC-V application processor, by protecting instructions right up to their execution against any type of modification. Secondly, based on authenticated memory encryption, we will study the possibility of using CHERI to define secure enclaves enabling cryptographic isolation between processes. The processor will be modified so that each process is encrypted with its own key and can have a secure life cycle. All keys must be efficiently protected in hardware.
Contact : olivier.savry@cea.fr
Embedded local blockchain on secure physical devices
The blockchain is based on a consensus protocol, the aim of which is to share and replicate ordered data between peers in a distributed network. The protocol stack, embedded in the network's peer devices, relies on a proof mechanism that certifies the timestamp and ensures a degree of fairness within the network.
The consensus protocols used in the blockchains deployed today are not suitable for embedded systems, as they require too many communication and/or computing resources for the proof. A number of research projects, such as IOTA and HashGraph, deal with this subject and will be analysed in the state of the art.
The aim of this thesis is to build a consensus protocol that is frugal in terms of communications and computing resources, and whose protocol stack will be implemented in a secure embedded device. This protocol must be based on the proof of elapsed time from our laboratory's work, which is also frugal, called Proof-of-Hardware-Time (PoHT), and must satisfy the properties of finality and fairness. The complete architecture of a peer node in the network will be designed and embedded on an electronic board including a microprocessor and several hardware security components, in such a way that the proof resource cannot be parallelized. Communication between peers will be established in a distributed manner.
Advancing Semantic Representation, Alignment, and Reasoning in Multi-Agent 6G Communication Systems
Semantic communications is an emerging and transformative research area, where the focus shifts from transmitting raw data to conveying meaningful information. While initial models and design solutions have laid foundational principles, they often rest on strong assumptions regarding the extraction, representation, and interpretation of semantic content. The advent of 6G networks introduces new challenges, particularly with the growing need for multi-agent systems where multiple AI-driven agents interact seamlessly.
In this context, the challenge of semantic alignment becomes critical. Existing literature on multi-agent semantic communications frequently assumes that all agents share a common understanding and interpretation framework, a condition rarely met in practical scenarios. Misaligned representations can lead to communication inefficiencies, loss of critical information, and misinterpretations.
This PhD research aims to advance the state-of-the-art by investigating the principles of semantic representation, alignment, and reasoning in multi-AI agent environments within 6G communication networks. The study will explore how agents can dynamically align their semantic models, ensuring consistent interpretation of messages while accounting for differences in context, objectives, and prior knowledge. By leveraging techniques from artificial intelligence, such as machine learning, ontology alignment, and multi-agent reasoning, the goal is to propose novel frameworks that enhance communication efficiency and effectiveness in multi-agent settings. This work will contribute to more adaptive, intelligent, and context-aware communication systems that are key to the evolution of 6G networks.
Enhancing Communication Security Through Faster-than-Nyquist Transceiver Design
In light of the growing demand for transmission capacity in communication networks, it is essential to explore innovative techniques that enhance spectral efficiency while maintaining the reliability and security of transmission links. This project proposes a comprehensive theoretical modeling of Faster-Than-Nyquist (FTN) systems, accompanied by simulations and numerical analyses to evaluate their performance in various communication scenarios. The study will aim to identify the necessary trade-offs to maximize transmission rates while considering the constraints related to implementation complexity and transmission security, a crucial issue in an increasingly vulnerable environment to cyber threats. This work will help identify opportunities for capacity enhancement while highlighting the technological challenges and adjustments necessary for the widespread adoption of these systems for critical and secure links.
Digital reconstruction of an industrial tank for the improvement of real-time monitoring instrumentation
In the context of industrial digitalization and real-time monitoring, accessing 3D fields (velocity, viscosity, turbulence, concentration, etc.) in real time can be crucial, as local sensor networks are sometimes insufficient to provide a comprehensive view of the system's dynamics. This PhD project aims to investigate a methodology for the real-time reconstruction of fields within an instrumented industrial tank equipped with a mixing system. The proposed approach relies on finite element modeling of the relevant physics within the tank (e.g., fluid dynamics, thermal processes) and model reduction techniques such as physics-based Machine Learning (virtual sensor approach). A key focus of this thesis will also be the development of the tank instrumentation and its associated acquisition chain, both to validate the models and to generate a database for applying the proposed methodology.
Enhanced Quantum-Radiofrequency Sensor
Through the Carnot SpectroRF exploratory project, CEA Leti is involved in radio-frequency sensor systems based on atomic optical spectroscopy. The idea behind the development is that these systems offer exceptional detection performance. These include high sensitivity´ (~nV.cm-1.Hz-0.5), very wide bandwidths (MHz- THz), wavelength-independent size (~cm) and no coupling with the environment. These advantages surpass the capabilities of conventional antenna-based receivers for RF signal detection.
The aim of this thesis is to investigate a hybrid approach to the reception of radio-frequency signals, combining atomic spectroscopy measurement based on Rydberg atoms with the design of a close environment based on metal and/or charged material for shaping and local amplification of the field, whether through the use of resonant or non-resonant structures, or focusing structures.
In this work, the main scientific question is to determine the opportunities and limits of this type of approach, by analytically formulating the field limits that can be imposed on Rydberg atoms, whether in absolute value, frequency or space, for a given structure. The analytical approach will be complemented by EM simulations to design and model the structure associated with the optical atomic spectroscopy bench. Final characterization will be based on measurements in a controlled electromagnetic environment (anechoic chamber).
The results obtained will enable a model-measurement comparison to be made. Analytical modelling and the resulting theoretical limits will give rise to publications on subjects that have not yet been investigated in the state of the art. The structures developed as part of this thesis may be the subject of patents directly exploitable by CEA.
Laser Fault Injection Physical Modelling in FD-SOI technologies: toward security at standard cells level on FD-SOI 10 nm node
The cybersecurity of our infrastructures is at the very heart in the digital transition on-going, and security must be ensured throughout the entire chain. At the root of trust lies the hardware, integrated circuits providing essential functions for the integrity, confidentiality and availability of processed information.
But hardware is vulnerable to physical attacks, and defence has to be organised. Among these attacks, some are more tightly coupled to the physical characteristics of the silicon technologies. An attack using a pulsed laser in the near infrared is one of them and is the most powerful in terms of accuracy and repeatability. Components must therefore be protected against this threat.
As the FD-SOI is now widely deployed in embedded systems (health, automotive, connectivity, banking, smart industry, identity, etc.) where security is required. FD-SOI technologies have promising security properties as being studied as less sensitive to a laser fault attack. But while the effect of a laser fault attack in traditional bulk technologies is well handled, deeper studies on the sensitivity of FD-SOI technologies has to be done in order to reach a comprehensive model. Indeed, the path to security in hardware comes with the modelling of the vulnerabilities, at the transistor level and extend it up to the standard cells level (inverter, NAND, NOR, Flip-Flop) and SRAM. First a TCAD simulation will be used for a deeper investigation on the effect of a laser pulse on a FD-SOI transistor. A compact model of an FD-SOI transistor under laser pulse will be deduced from this physical modelling phase. This compact model will then be injected into various standard cell designs, for two different objectives: a/ to bring the modelling of the effect of a laser shot to the level of standard cell design (where the analog behaviour of a photocurrent becomes digital) b/ to propose standard cell designs in FD-SOI 10nm technology, intrinsically secure against laser pulse injection. Experimental data (existing and generated by the PhD student) will be used to validate the models at different stages (transistor, standard cells and more complex circuits on ASIC).
Ce sujet de thèse est interdisciplinaire, entre conception microélectronique, simulation TCAD et simulation SPICE, tests de sécurité des systèmes embarqués. Le candidat sera en contact/encadré avec deux équipes de recherche; conception microélectronique , simulation TCAD et sécurité des systèmes embarqués.
Contacts: romain.wacquez@cea.fr, jean-frederic.christmann@cea.fr, sebastien.martinie@cea.fr
Super-gain miniature antennas with circular polarization and electronic beam steering
Antenna radiation control in terms of shape and polarization is a key element for future communication systems. Directive compact antennas offer new opportunities for wireless applications in terms of spatial selectivity and filtering. This leads to a reduction in electromagnetic pollution by mitigating interferences with other communication systems and reducing battery consumption in compact smart devices (IoT), while enabling also new use modes. However, the conventional techniques for enhancing the directivity often lead to a significant increase of the antenna size. Consequently, the integration of directional antennas in small wireless devices is limited. This difficulty is particularly critical for the frequency bands below 3 GHz if object dimensions are limited to a few centimeters. Super directive/gain compact antennas with beam-steering capabilities and operating on a wideband or on multi-bands are an innovative and attractive solution for the development of new applications in the field of the connected objects. In fact, the possibility to control electronically the antenna radiation properties is an important characteristic for the development of the future generation and smart communication systems. CEA Leti has a very strong expertise in the domain of superdirective antennas demonstrating the potentials of the use of ultra-compact parasitic antenna arrays. This PhD project will take place at CEA Leti Grenoble in the antennas and propagation laboratory (LAPCI). The main objectives of this work are: i) contribution to development of numerical tools for the design and optimization of superdirective compact arrays with beam-steering capabilities; ii) the study of new elementary sources for compact antenna arrays; iii) the realization and experimental characterization of a supergain compact array with circular polarization and beam-steering capabilities. This work will combine theoretical studies and model developments, antenna design using 3D electromagnetic software, prototyping and experimentations.