RIOT OS Paves the Way for Implementation of High-Performance MAC Protocols

Implementing new, high-performance MAC protocols requires real-time features, to be able to synchronize correctly between different unrelated devices. Such features are highly desirable for operating wireless sensor networks (WSN) that are designed to be part of the Internet of Things (IoT). Unfortunately, the operating systems commonly used in this domain cannot provide such features. On the other hand, "bare-metal" development sacrifices portability, as well as the mul-titasking abilities needed to develop the rich applications that are useful in the domain of the Internet of Things. We describe in this paper how we helped solving these issues by contributing to the development of a port of RIOT OS on the MSP430 microcontroller, an architecture widely used in IoT-enabled motes. RIOT OS offers rich and advanced real-time features, especially the simultaneous use of as many hardware timers as the underlying platform (microcontroller) can offer. We then demonstrate the effectiveness of these features by presenting a new implementation, on RIOT OS, of S-CoSenS, an efficient MAC protocol that uses very low processing power and energy.Comment: SCITEPRESS. SENSORNETS 2015, Feb 2015, Angers, France. http://www.scitepress.or

Safety Evaluation of Critical Applications Distributed on TDMA-Based Networks

Critical embedded systems have to provide a high level of dependability. In automotive domain, for example, TDMA protocols are largely recommended because of their deterministic behavior. Nevertheless, under the transient environmental perturbations, the loss of communication cycles may occur with a certain probability and, consequently, the system may fail. This paper analyzes the impact of the transient perturbations (especially due to Electromagnetic Interferences) on the dependability of systems distributed on TDMA-based networks. The dependability of such system is modeled as that of "consecutive-k-out-of-n:F" systems and we provide a efficient way for its evaluation

Allocation of control and data channels for Large-Scale Wireless Sensor Networks

Both IEEE 802.15.4 and 802.15.4a standards allow for dynamic channel allocation and use of multiple channels available at their physical layers but its MAC protocols are designed only for single channel. Also, sensor's transceivers such as CC2420 provide multiple channels and as shown in [1], [2] and [3] channel switch latency of CC2420 transceiver is just about 200$\mu$s. In order to enhance both energy efficiency and to shorten end to end delay, we propose, in this report, a spectrum-efficient frequency allocation schemes that are able to statically assign control channels and dynamically reuse data channels for Personal Area Networks (PANs) inside a Large-Scale WSN based on UWB technology

Ethyl 5-chloro­methyl-2-methyl­sulfanyl-7-phenyl-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidine-6-carboxyl­ate

In the title compound, C16H17ClN4O2S, the bicyclic triazolopyrimidine ring system is nearly planar and oriented with respect to the benzene ring at a dihedral angle of 87.24 (3)°. In the crystal structure, inter­molecular N—H⋯N hydrogen bonds link the mol­ecules into centrosymmetric dimers; an intra­molecular C—H⋯O hydrogen bond is also present

HMAS: enabling seamless collaboration between drones, quadruped robots, and human operators with efficient spatial awareness

Heterogeneous robots equipped with multi-modal sensors (e.g., UAV, wheeled and legged terrestrial robots) provide rich and complementary functions that may help human operators to accomplish complex tasks in unknown environments. However, seamlessly integrating heterogeneous agents and making them interact and collaborate still arise challenging issues. In this paper, we define a ROS 2 based software architecture that allows to build incarnated heterogeneous multi-agent systems (HMAS) in a generic way. We showcase its effectiveness through a scenario integrating aerial drones, quadruped robots, and human operators (see https://youtu.be/iOtCCticGuk). In addition, agent spatial awareness in unknown outdoor environments is a critical step for realizing autonomous individual movements, interactions, and collaborations. Through intensive experimental measurements, RTK-GPS is shown to be a suitable solution for achieving the required locating accuracy

Ethyl 2-benzyl­sulfanyl-7-(2-chloro­phen­yl)-5-methyl-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidine-6-carboxyl­ate

In the title compound, C22H21ClN4O2S, the bicyclic triazolopyrimidine ring system is nearly planar, and oriented at dihedral angles of 89.45 (3)° with respect to the chlorobenzene ring and 87.03 (3)° with respect to the terminal phenyl ring. In the crystal structure, mol­ecules are linked by π–π stacking inter­actions between the triazolopyrimidine rings [centroid–centroid distances of 3.88 (1) and 3.63 (1) Å]

Protocoles auto-adaptatifs énergie-trafic pour les réseaux de capteurs sans fil

National audienceLa plupart des protocoles conçus pour les réseaux de capteurs sans fil se reposent sur le principe de " duty-cycle " afin d'économiser l'énergie. Cette approche peut poser des problèmes de performances quand le réseau doit transporter des données de quantité importante sur une courte période (c'est à dire une rafale de données). Dans ce papier nous traitons deux problèmes importants : comment ajuster le " duty-cycle " en fonction de la variation du trafic et comment transporter plus efficacement des rafales de données afin d'assurer une certaine qualité de service tout en minimisant la consommation de l'énergie. Nous faisons d'abord une analyse des principaux protocoles à " duty-cycle " existants et discuter des problèmes restants, puis présentons nos deux protocoles Queue-MAC et S-CoSenS qui résolvent efficacement ces deux problèmes posés

Network interoperability and QoS for smart homes

International audienceWe show some problems that we have met when building a smart house for monitoring the daily activity and health of the elderly. The talk only focuses on the data communication network aspect with the problems of how to ensure the interoperability and QoS of the data communication. A communication gateway architecture, as well as a low power wireless sensor network based QoS protocol are described and their use for smart house building is discussed

Matrix-DBP for (m,k)-firm real time guarantee

Colloque sans acte à diffusion restreinte. nationale.National audienceThis presentation outlines the application context of (m,k)-firm real-time paradigm, shows where are the problems when applying the DBP algorithm to the real-time context and then details our solutions based on the new Matrix-DBP algorithm. Future research work related to the (m,k)-firm paradigm is indicate