PhD Defence: “Bidirectional Visible Light Communications for the Internet of Things”, Alexis DUQUE, Amphitheater, Chappe Building, 9th of October 2018, at 14h00

Title

Bidirectional Visible Light Communications for the Internet of Things

Abstract

With the exponential growth of the Internet of Things, people now expect every household appliance to be smart and connected. At the same time, smartphones have become ubiquitous in our daily life. Their continuous performance improvement and their compatibility with a broad range of radio protocols as WiFi, Bluetooth Low Energy (BLE) or NFC make them the most convenient way to interact with these smart objects. However, providing wireless connectivity with BLE or NFC means adding an extra chipset and an antenna, increasing the object size and price. Previous works already have demonstrated the possibility of receiving information through visible light using an unmodified smartphone thanks to its camera. Also, LED-to-LED communication for smart devices like toys has been shown previously. However, past efforts in LED to camera communication for IoT device communication have been limited.

In this work, we design LightIoT, a bidirectional visible-light communication (VLC) system between a low-cost, low-power colored LED that is part of an IoT device and an off-the-shelf smartphone. The IoT device is thus able to send and receive information through its LED, while the smartphone uses its camera to receive data and its flashlight to send information. We implement and experimentally evaluate a LED-to-camera VLC system, designed specifically for small LEDs. The proposed solution exploits the rolling shutter effect of unmodified smartphone cameras and an original decoding algorithm, achieving a throughput of nearly 2 kb/s.
Based on the insight gained from an extensive experimental study, we model, for the first time in the literature, the LED-to-camera communication channel. We propose a Markov-modulated Bernoulli process model, which allows us to easily study the performance of different message retransmission strategies. We further exploit this model to implement a simulator for LED-to- Camera communications performance evaluation.

In order to achieve bi-directional communications, we evaluate flashlight-to- LED communications using non-rooted smartphones and small LEDs. With these constraints, our implementation achieves a throughput of 30 bits/second. While limited, this is enough for a feed-back channel coming to support the required redundancy mechanisms. Some of these redundancy mechanisms are based on random linear coding, never tested previously in VLC.
Therefore, we design and implement, for the first time in the literature, a pseudo random linear coding scheme especially fitted for line-of-sight LED-to-camera conditions. Experimental evaluation highlights that this type of approach increases the goodput up to twice compared to classical retransmission strategies.

Finally, we compare the energy consumption of LightIoT with the one of a BLE module with similar activity. Our results show that using the LED for communication purposes reduces the energy consumption under a normal usage behavior.

Jury

  • Emmanuel CHAPUT, Professeur des Universités, INP Toulouse, Rapporteur
  • Anne JULIEN-VERGONJANNE, Professeur des Universités Univ. Limoges, Rapporteur
  • Josep PARADELLS ASPAS, Professeur UPC, Rapporteur
  • Luc CHASSAGNE, Professeur des Universités UVSQ, Examinateur
  • Valeria LOSCRI, Chargé de Recherche INRIA Lille, Examinateur
  • Hervé RIVANO, Professeur des Universités INSA Lyon, Directeur de thèse
  • Razvan STANICA Maître de Conférences INSA Lyon, co Directeur de thèse

Seminar of Lionel MOREL (CEA Grenoble) on October 18th at 2pm

The next CITI seminar will take place on October 18 th, at 2pm. This seminar entitled “Polen: une approche SW/HW pour la confidentialité des programmes et des données” will be presented by our former colleague Lionel MOREL from CEA Grenoble.

Titre : Polen: une approche SW/HW pour la confidentialité des programmes et des données.

Résumé : D’aucuns voudraient connecter un nombre grandissant d’objets, entre eux, mais aussi au réseau internet, pour permettre la collecte d’un nombre toujours plus grand d’informations et réaliser ainsi l’augmentation de nos vies jusque-là visiblement sous-dimensionnées. Mais connecter des objets, y stocker des informations personnelles, tout en les rendant accessibles facilement au reste du monde ouvre la voie à toute une série d’usages dangereux pour nos données et nous-mêmes.

Les approches de protection matérielles traditionnellement utilisées (eg pour la carte à puce) sont certes très efficaces, mais elles sont également très coûteuses en développement, en certification, et en déploiement. Au CEA, nous étudions comment des approches logicielles peuvent venir en complément de ces approches matérielles pour augmenter le niveau de confiance placé dans l’objet tout en limitant les coûts et en flexibilisant l’application des protections.

Dans cet exposé, je présenterai un cas particulier d’approche mêlant contre-mesures matérielles et logicielles, que nous développons actuellement. Il sera question d’attaques par canaux cachés, de reverse-engineering (un peu) de compilation dynamique, de chiffrement de code (plus), de pompe à insuline et de lampes connectées aussi, et de fin du monde peut-être.

Bio : Après une thèse sur les langages de programmation dédiés aux systèmes critiques, soutenue à Verimag en 2005 et quelques voyages scientifico-culturels en Bretagne et Finlande, Lionel Morel a intégré l’INSA Lyon en 2007 et le CITI en 2009. Il y a mené des travaux de recherche entre autres sur la programmation et l’évaluation de performances de machines parallèles, tout en enseignant les systèmes d’exploitations, l’architecture des ordinateurs et la compilation. Depuis 2017, il est détaché auprès du CEA, à Grenoble, où il travaille sur l’usage de la compilation pour la sécurité.


PhD Defence: “Ultra Narrow Band based IoT networks”, Yuqi MO, Amphitheater, Chappe Building, 26th of September 2018, at 14h00

Title

Ultra Narrow Band based IoT networks

Abstract

Sigfox rises as a promising candidate dedicated for long-distance and low-power transmissions in the IoT backgrounds. Ultra Narrow Band (UNB), being the communication technology chosen by Sigfox, allows to transmit information through signals whose bandwidth is very limited, typically 100 Hz. Due to the imprecision restraint on electronic devices, it is impossible to transmit UNB signals in orthogonal channels. The natural radio access for this kind of system is thus random ALOHA, in both time and frequency domain. This random access can induce collisions which degrades the networks performance.

The aim of this thesis is to characterize the capacity of UNB based networks, as well as to enhance its performance, by considering the randomness in time and frequency.

The first contribution of the thesis, is the theoretical and numerical capacity evaluation under idealized and realistic channel conditions, for mono base station (BS) case. Under idealized conditions, we have quantified this capacity for generalized ALOHA case and extended for replications. We highlight the time-frequency duality in UNB systems, and that there exists an optimum replication number for a given network parameter set.

Under realistic conditions, we have taken into account the specific spectral interference of UNB systems and propagation path loss (without and with Rayleigh fading) to characterize the performance, with the aid of stochastic geometry.

The second contribution is the enhancement of UNB network performance in single BS case. We propose to use successive interference cancellation (SIC) in UNB networks, which allows to mitigate the interference. We have provided a theoretical analysis by considering both SIC and the spectral interference, for mono-BS case. We bring to light the efficiency of SIC in enhancing UNB system performance.

The third contribution is the improvement of UNB systems, by exploiting the multiple BS diversity. An analytical performance evaluation considering the simplest selection combining is conducted. In particular, we consider the interference viewed by all the BSs are correlated. Then we apply more complex signal combining technologies such as MRC (max ratio combining) and EGC (equal gain combining), and even interference cancellation across multi-BS in UNB networks. We evaluate the performance improvement that each technology can bring, and compare them with each other. We highlight the efficiency of these multi-BS technologies which allow us to achieve significant performance enhancement compared to mono-BS (e.x. 125 times better performance with global SIC).

Last but not least, we experimentally verify the the spectral interference model and network capacity on a cognitive radio testbed.

Jury

  • Mr. ANTON-HARO Carles, Directeur de Recherch, à Centre technology de Telecommunications de Catalunya (Reviewer)
  • Mr. DI RENZO Marco, HDR à Université Paris-Saclay (Reviewer)
  • Mme. HELARD Maryline, Professeur à l’INSA-Rennes (Member)
  • Mr. VERDONE Roberto, Professeur à University of Bologna (Member)
  • Mr. GORCE Jean-Marie, Professeur à l’INSA-Lyon (Supervisor)
  • Mme. GOURSAUD Claire, HDR à l’INSA-Lyon (Co-Supervisor)