Archives des séminaires

In the automotive, softwares are more and more present  However, during the development lifecycle, errors and flaws can be introduced and lead to failures. Due to the lack of automatic and formal means, verifying that the softwares are bug free and compliant with the requirements is challenging. In this presentation we propose an approach inspired by formal methods that helps analyse and validate the developped softwares.

Pandoc is a computer program written in Haskell (a functional programming language) that 

converts documents from one of many possible input formats (docx, epub, html, json, latex, 

markdown, odt...) and to one of many possible output formats (beamer, docx, epub, html, 

latex, markdown, odt, pdf, pptx, slidy...) 

In this talk we will present pandoc, its internal representation of documents and its 

processing flow. We will then show how to produce beamer/PDF or HTML/javascript presentations

from markdown inputs. Finally, we will show how the lua scripting language, the pandoc templates 

and the beamer templates can be used to customize pandoc in order to produce advanced presentations 

in the Telecom Paris style.

in 3C14 at 10am

Abstract:

One of the next frontiers in communication technology is to re-think methods of sharing
spectrum among wireless transmitters. In this talk, I will discuss recent results on
characterizing the fundamental tradeoff between the density of users (ratio of active users and the number of degrees of freedom available per frame) and 
the minimal required energy-per-bit (Eb/N0). In the regime of interest for the Internet-of-Things, 
the payload of each user is about 100 data bits. This is too small for the asymptotic Shannon theory to provide any guidance and thus we needed to develop new tools for analysis.
A surprising discovery is existence of coded-access schemes that are able to almost perfectly reject
the multi-user interference, so that increasing the density of users
(without increasing space-time-frequency resources) does not lead to
any deterioration of service. Practically important is that known
MAC architectures are not capable of attaining this effect. A similar analysis and effects
arise in the problem of (unsourced) random-access over the AWGN channel, which we will
discuss as well.

in A301 at 2pm

Abstract:

Suppose that Alice wants to convey to Bob the results of k iid fair coin flips, using n times an iid binary symmetric channel (that is, in each use Alice's inout is flipped with probability e). We measure the performance by the expected Hamming distortion D, i.e., the probability that Bob's guess of a coin flip after seeing the channel outputs is wrong. Let D*(k, r, e) be the optimal attainable expected distortion, where r=n/k. For any fixed r, as k tends to infinity the optimum is attained by the separation principle: Alice and Bob should use the concatenation of optimal compression and digital communication. However, other approaches, known collectively as joint source-channel coding (JSCC) may be superior in terms of finite-blocklength performance (D* for limited k) and robustness (the performance when Alice does not know e). For r=1, a simple scalar (k=1) scheme attains D* universally over all e, but in general there are many open questions regarding the fundamental bounds of JSCC. We present some old and new results, and in particular show a surprising connection: an impossibility bound on robustness leads to a finite-blocklength bound.
Based in part on joint work with Or Ordentlich and Yury Polyanskiy.

in A301 at 10am

Abstract:

We consider a communication setup where transmitters wish to simultaneously sense network states and convey messages to intended receivers. The scenario is motivated by joint radar and vehicular communications where the radar and data applications share the same bandwidth.  First, I present a theoretical framework to characterize the fundamental limits of such a setup for memoryless channels with i.i.d. state sequences. Then, I present our recent work on joint radar and communication using Orthogonal Time Frequency Space (OTFS).  Although restricted to a simplified scenario with a single target, our numerical examples demonstrated that two modulations provide as accurate radar estimation as Frequency Modulated Continuous Waveform (FMCW), a typical automotive radar waveform,  while providing a non-negligible communication rate for free.