CITI Talk: “New achievable rate regions for fundamental network information theory problems”, Arun Padakandla (Purdue University, IN, USA), 17/07 14h

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New achievable rate regions for fundamental network information theory problems
Arun Padakandla (Purdue University, IN, USA)
In this talk, we consider the fundamental information-theoretic problems of characterizing 2) the capacity regions of channel coding problems such as broadcast, interference and 2) necessary and sufficient conditions for joint source-channel coding of distributed correlated sources. Going beyond independent and identically distributed codewords, we propose the ensemble of coset codes possessing algebraic closure properties and derive new achievable rate regions (inner bounds) to the capacity regions of the former problems with three or more receivers. Our findings are based on characterizing performance of new encoding and decoding rules that exploit the algebraic properties of these codes. Next, we observe that the conventional approach of single-letter coding is sub-optimal for joint source channel coding over multiple access and interference channels. We propose a novel multi-letter coding technique based on appropriately stitching together single-letter techniques. Most importantly, we characterize an inner bound to its performance via a single-letter expression, which is proven to strictly enlarges currently known single-letter achievable rate regions based on single-letter coding. This puts forth a useful technique for characterizing new inner bounds to problems that might not permit an optimal single-letter technique.

CITI Talk: “Machine Learning for Solving Software Maintenance and Evolution Problems”, Gabriela Czibula, Prof. & Istvan Czibula, Ass. Prof, University of Babes-Bolyai, Computer Science Dept, 10/07, 11h

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Gabriela Czibula, Prof., and Istvan Czibula, Ass. Prof, University of Babes-Bolyai, Computer Science Dept will present “Machine Learning for Solving Software Maintenance and Evolution Problems + Presentation of the Faculty of Mathematics and Computer Science, Babes-Bolyai University and MLyRE Research Group” at the CITI Lab on Monday, July 10th 2017.

CITI Talk: “Medium Access Protocols for Wireless Sensor Networks” by Abdelmalik Bachir, Biskra University, Algeria in Amphi Chappe, June 20th 2017

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There has been a growing interest on understanding and optimizing Wireless Sensor Network MAC protocols in recent years, where the limited and constrained resources have driven research towards primarily reducing energy consumption of MAC functionalities. In this talk, we expose the prime focus of WSN MAC protocols, design guidelines that inspired these protocols, as well as drawbacks and shortcomings of the existing solutions and how existing and emerging technology will influence future solutions.

Abdelmalik Bachir received the graduate degree from the National Institute of Informatics, Algiers, Algeria, in 2001, the DEA diploma in informatics from the University of Marseille, France, in 2002, and the PhD degree from Grenoble Institute of Technology, France, in 2007. He took research positions at Avignon University, France Telecom R&D, Grenoble Institute of Technology, Imperial College London, as well as CERIST Research Centre, Algiers. Currently, he is a professor at Biskra University, Algeria and a consultant at Imperial Innovations. His research interests include: MAC and Routing protocols for wireless networks, wireless network deployment optimisation, mobile user mobility profiling, and inter-vehicle communication.

CITI Talk: “Entropy and Cost of Anti Uniform Huffman Codes” by Daniela Tarniceriu, Technical University “Gh. Asachi” of Iasi, Romania in Amphi Chappe, June 12th

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In this talk, the class of anti-uniform Huffman (AUH) codes for anti-uniform sources with finite and infinite alphabets is considered. The characteristics of such sources as well as Huffman codes for such sources are first recalled. The sequence of bits corresponding to the output of a anti-uniform source encoded with a Huffman code is modeled by a Markov source. Its characteristics are derived from the encoding procedure describing the Huffman code. The Huffman encoding process is viewed as a transmission through a channel, which input would be the input symbols, and its output, the output bits.
The class of AUH sources is known for their property of achieving minimum redundancy in several situations. It has been shown that AUH codes potentially achieve the minimum redundancy of a Huffman code of a source for which the probability of one of the symbols is known. The AUH codes are efficient in highly unbalanced cost regime, with minimal average cost among all prefix–free codes. These properties determine a wide range of applications and motivate for the study of these sources from the information theory perspective.
Starting from the AUH structure, the average codeword length, the code entropy and the average cost are derived. These results are customized for finite and infinite sources with different distributions (Poisson, negative binomial, geometric and exponential).

Daniela Tarniceriu (PhD. 1997) is a full professor at the Technical University “Gh. Asachi” of Iasi, Romania since 2001. Her research interests are in the fields of information theory, digital signal processing, statistical signal processing, data compression and encryption. She is the co-author of 8 books, 85 journal papers and 65 conference papers. She was involved in several research grants: two as scientific leader, two as coordinator, and 12 as scientist.
Since 2016, she is the Dean of the Faculty of Electronics, Telecommunications and Information Technology (ETTI) of the Technical University “Gh. Asachi” of Iasi, Romania and between 2008 and 2016 she was the head of the “Telecommunications” Department of the ETTI. Since 2013 she is the head of the Doctoral School of the ETTI.

CITI Talk: “Event Detection in Nanoscale Networks via Molecular Communication” by Trang Mai, Queen’s University of Belfast on June, 16th – 14:00 in TD C

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Recent advances in synthetic biology and chemistry are making it possible to form
networks consisting of nanoscale devices—known as nanomachines—with
applications in medicine and environmental protection. These nanoscale devices,
often known as nanomachines, have a limited ability to sense their environment,
communicate and take simple actions. A key potential application is therefore event
detection, where the nanoscale network seeks to identify the presence of an
undesirable state, such as markers of an illness.

To support event detection, the nanoscale network must be able to communicate
observations from sensing nanomachines to a fusion center, where a decision can
be made. Due to strict size and energy constraints, this communication is a
challenging problem. Recently, a new approach known as molecular communication
has been proposed, where information is encoded in the state of molecules, such as
the release time, number, or type of molecules, which diffuse from the transmitter to
the receiver through a fluid. This new medium has dramatically different features
than traditional electromagnetic and accoustic media, which requires new channel
models, as well as encoding and decoding strategies.

In this seminar, I will introduce the principles of molecular communication,
highlighting the differences from traditional communication schemes. I will then show
how molecular communication can support collaboration in nanoscale networks. In
particular, I will present a new event detection scheme for nanoscale networks,
which accounts for the unique characteristics of the underlying molecular
communication links—known as the anomalous diffusion channel.

Speaker biography

Mai Cong Trang currently is PhD candidate in Molecular Communications under the
supervision of Dr. Trung Q. Duong at Queen’s University Belfast and Dr. Malcolm
Egan at INSA Lyon. He received the B.S. degree in Electronic and Electrical
Engineering in 2008 at Le Quy Don Technical University, Vietnam. Then, in 2013, he
received the M.S. degree in Electronics and Communications Engineering at The
University of Electro‐Communications, Japan. His current research interests include
Molecular Communications, Nanomachine Networks and Bio-inspired Networks.

CITI talks: “Modeling Energy Packets Networks with Markov chains: Analytical Solutions” by Jean-Michel Fourneau, UVSQ on 6th April

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In this talk, Jean-Michel Fourneau will present some analytic solutions of Queueing Network models that jointly model the data packets and the energy consumed by the transmission and reception. These models are based on the energy discretization, we talk then about energy Packets.


Jean-Michel Fourneau is Professor of Computer Science at the University of Versailles St Quentin, France since 1992. He was formerly with Ecole Nationale des Telecommnications, Paris and University of Paris XI Orsay as an Assistant Professor. He graduated in Statistics and Economy from Ecole Nationale de la Statistique et de l’Administation Economique, Paris and he obtained is PHD
and his habilitation in Computer Science at Paris XI Orsay in 87 and 91 respectively. He is a member of IFIP WG7.3. His recent research interests are
algorithmic performance evaluation, Stochastic Automata Networks, G-networks, stochastic bounds, and application to high speed networks, all optical networks and energy consumption.

CITI Talk: “POETS : partially ordered event triggered systems”, Dr David Thomas, Imperial College on 5th April 16:00

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POETS : partially ordered event triggered systems

The POETS project is a five-year effort to build a combined software and hardware system which allows applications to be split into 1M+ concurrent state machines, and then to execute them on 100K+ concurrent hardware threads across 100+ tightly-coupled compute nodes. To achieve this we use an event-driven compute system with no global barriers or shared state, and re-write applications to use globally asynchronous algorithms. This talk will give an overview of the hardware that is being built, and show how applications such as finite-volume solvers can be re-cast as a asynchronous system.


CITI Talk: “Two Channels with Almost No Benefit from CSI”, by Ligong Wang, on 27th March

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The next CITI talk will take place on 27th March at 3 pm in room TD-C.

This talk entitled “Two Channels with Almost No Benefit from CSI” will be presented by Ligong Wang.


For many communication channels, causal or noncausal channel-state information (CSI) at the transmitter can help to significantly increase their communication capacity. In this talk we discuss two channels for which this is not the case. The first is the very noisy channel. We show that noncausal CSI at the transmitter provides little additional capacity improvement over causal CSI. The second channel is the Poisson channel with random, time-varying dark current. On this channel, capacity improvement from both causal and noncausal CSI is shown to be negligible.

Speaker biography

Ligong Wang received the B.E. degree in electronic engineering from Tsinghua University, Beijing, China, in 2004 and the M.Sc. and Ph.D. degrees in electrical engineering from ETH Zurich, Switzerland, in 2006 and 2011 respectively. In the years 2011-2014, he was a Postdoctoral Associate at the Department of Electrical Engineering and Computer Science at the Massachusetts Institute of Technology, Cambridge, MA, USA . He is now a researcher (chargé de recherche) with CNRS, France, and is affiliated with ETIS laboratory in Cergy-Pontoise. His research interests include classical and quantum information theory, and digital, in particular optical communications.

CITI Talk: “Broadcasting with delayed CSIT: finite SNR analysis and heterogeneous feedback”, by Chao HE, on 15th March

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The next CITI talk will take place on 15th March at 11 am in Amphi Chappe.

This talk entitled “Broadcasting with delayed CSIT: finite SNR analysis and heterogeneous feedback” will be presented by Chao HE.


One of the key techniques for future wireless networks, namely state-feedback enabled interference mitigation, is explored with information theoretical tools under some realistic settings. In order to verify the usefulness of delayed CSIT in harsh situations, we investigate it with finite SNR and/or feedback heterogeneity in a broadcast communication setup. In the first part of this talk, we are mainly interested in showing the finite SNR performance of delayed CSIT and the similarity between the results in Gaussian and erasure channels. Several relatively simple schemes are proposed in multi-user broadcast channels when states are assumed to be fully known at the destinations but only strictly causally at the transmitter. Enhancement in terms of higher symmetric rates and more input alphabet options are then characterized when analyzing the corresponding regions in Gaussian/erasure cases. In the second part of this talk, algorithms adapted to heterogeneous feedback are targeted as only part of communication nodes are involved in the feedback process. In particular, we concentrate on 1) broadcast channel with feedback from partial receivers, 2) broadcast relay channel with feedback at the relay. Improvements on achievable rates are justified in either cases via analysis and some examples.

Speaker biography

Chao He received his B.E. degree in Electrical Engineering from Southeast University in 2012, and the M.Sc. degree in SAR from Supélec in 2013. He obtained the Ph.D. degree from CentraleSupélec of Université Paris Saclay in 2016. His current research interests lie in the areas of multi-user information theory and limited feedback.

CITI Talk: “​​Challenges of a Reflective Platform”, by Stéphane Ducasse, on 24th November

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The next CITI talk will take place on 24th November at 11 am in Amphi Chappe.

This talk entitled “Challenges of a Reflective Platform” will be presented by Stéphane Ducasse directeur de recherche at Inria-Lille..


Pharo is a live programming reflective dynamic language and environment. His tools are delivering an excellent programmer experience and are heavy user of its reflective abilities.
In this talk we will present briefly Pharo an immersive reflective platform and programming language ( and focused on:
(1) the problems we encounter daily (how to update core libraries while they are used to execute the updater itself, how can we get VM execution benefit from hot state right at system startup and without warming up, how can we isolate reflective parts of the system, what are the code representations we need to make happy the VMs and IDE)
(2) the infrastructure that we would like to have: since we are able to bootstrap the core of the system under 80 k, we can start thinking about multiple versions of the system coexisting, the question of the memory model is then important. Another question is how can we build a system where users can decide when they want to move code from one version to the other ones. Similarly, we would like to resume work on PharoNoOS and work on Xen hypervisor to gain benefit of hot hotspot and fast boot time.

Speaker biography

Stéphane is directeur de recherche at Inria. He has more than 20 years of experience in software maintenance. He leads the RMoD ( team. He is expert in two domains: object-oriented language design and reengineering.  He worked on traits, composable groups of methods. Traits have been introduced in  Pharo, Perl, PHP and  under a variant into Scala, Fortress of SUN Microsystems.  He is also expert on software quality, program understanding, program visualizations, reengineering and metamodeling. He is one of the developer of Moose, an open-source software analysis platform  He created a company building dedicated tools for advanced software analysis. He is one of the visionary core developers behind Pharo a new exciting reflective and immersive dynamically-typed language. According to google, his h-index is 49 for about 10 K citations. He is writing some new books around Pharo and having fun building a great and exciting system.