Published on 19 February 2024
Following her first ERC grant in 2017, Michèle Wigger has been awarded a second European grant to support her work in information theory. The Telecom Paris researcher will continue to study the fundamental limits of communication systems, but will focus her main research efforts on the theoretical side.
“Information theory” provides a mathematical framework for understanding how to measure and optimize the transfer of information. Although developed by Claude Shannon in 1948, it has paved the way for a wide range of current research in a number of fields including telecommunications, data compression, cryptography, and machine learning. “The range of application is very extensive, so you can explore the subject and never get bored!” confirms Michèle Wigger enthusiastically.
Starting with her thesis, the Telecom Paris researcher made information theory her favorite research topic. After both her master’s thesis and doctoral thesis were awarded a medal at ETH Zurich, she went on to do a postdoctorate at the University of California at San Diego, before joining the Communications and Electronics department at Télécom Paris at the end of 2009.
Much of her work focuses on telecommunications, a sector that has evolved tremendously over the last few decades. “Today, ‘telecoms’ go beyond the simple transmission of data from one point to another. They serve very precise and varied purposes, and in order to increase their efficiency they must be adapted to these purposes. A typical goal, for example, is to coordinate autonomous vehicles so that they don’t crash. That’s why it’s now called ‘task-oriented’ or ‘goal-oriented communication’,” she explains. “This constant evolution in telecommunications is a real driver for me and for the projects I lead.”
In 2017, Michèle Wigger’s research on task-oriented communications was supported by a first European excellence grant (ERC Starting Grant, project title “Context- and Task-Oriented Communication”). The five-year project consisted in establishing the fundamental limits of different communication scenarios, for example systems with caches, i.e., user-side storage memories. The principle is to model a system mathematically and establish its limits, demonstrating both that they are achievable and that they cannot be exceeded. This could be the highest throughput, the largest compression rate, or the lowest probability of detection error.
In this first ERC project, the researcher and her team focused mainly on coding schemes. In general, they designed and put into practice new coding schemes, for various applications, which are capable of sending more information than traditional codes. The efficiency of these codes was verified by their implementation on a testbed. For some of these codes, they also derived theoretically, through mathematical proofs, the structure of optimal codes and their associated throughputs. “By identifying the optimum throughput, we want to check how close the improved codes we have developed are to the optimum,” explains the researcher.
For example, one line of research of this project involved distributed computing networks: systems in which data is distributed between several connected computers, enabling a calculation to be carried out more efficiently. However, these distributed calculations are subject to rigorous constraints in terms of power and energy, the computers must be able to communicate with each other in an energy-efficient way. Scientists at Telecom Paris have therefore looked at the limits of the different communication scenarios for these systems.
While Michèle Wigger strives to push her mathematical and theoretical research towards practical systems, she makes no secret of her preference. “For the first project, we went quite far with the implementation, but what interests me in the study of limits is really the fundamental aspect, the theorems, the proof techniques… For that, paper and a pencil are all you need,” she says with a smile.
At the end of 2023, she returned to her theoretical predilection and was awarded a second European grant (ERC Consolidator Grant) to explore the Fundamental Limits of Sensing Systems. The project – also over five years, starting in June 2024 – will focus primarily on mathematical proof techniques to demonstrate that for given systems it is not possible to exceed certain limits. This is a theoretical challenge because, as the researcher explains, “when analyzing a system, it’s easier to show that you can achieve a certain performance, – for example, a better throughput – than to show that you can’t go beyond a certain value. The latter requires higher levels of abstraction”.
Nevertheless, the proposed theoretical research also serves concrete practical frameworks. For example, the framework of integrated sensing and communication – better known by the acronym ISAC, which is predicted to be a major component in automotive vehicles or industrial robots. A relatively new proof technique, called “change of measure converse”, will be particularly explored by the researcher and her future team, as it is adapted to the analysis of these systems.
What interests me in the study of limits is really the fundamental aspect.In this new project, the researcher is also planning a quantum research axis. The inspiration for this came directly from her recent sabbatical year, straddling the Physics department at ETH and the Mathematics department at the University of Zurich. During her sabbatical, the scientist familiarized herself with the information-theoretic tools needed to tackle quantum communication systems, as well as with “post-quantum” coding for cryptographic applications, to withstand future quantum attacks.
Michèle Wigger’s attraction to cryptography and quantum science goes right back to her studies. “If I had to do another thesis, I’d do it in one of these fields. The problem is that I’m too passionate about information theory! I’ve got all kinds of desires to work in other areas, but I can never seem to move on to anything else,” she jokes. Nevertheless, the researcher reports that she has taken stock of her experience: “I’m halfway through my career, and I’d never taken a sabbatical before. So I said to myself that this was the right time and off I went!”
Exploring the quantum discipline offers the researcher the opportunity for future collaborations: “There are a huge number of quantum teams on the Saclay plateau with whom I hope to work, on this project and in the future”. These collaborations are an important part of the scientist’s career, and she herself is deeply involved in the community of research on information theory. Michèle Wigger is currently involved in organizing the 2025 edition of the IEEE International Symposium on Information Theory (ISIT), the largest conference in her field. “It’s not a very large community, so it’s easy to make connections at workshops and conferences.” The researcher compares these meetings to a river, because “you get carried away by the questions and problems raised by other researchers, by different techniques…”. There’s no doubt that for this explorer of limits, the journey still holds many discoveries in store.
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