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

Channel and active component abstractions for WSN programming - a language model with operating system support

To support the programming of Wireless Sensor Networks, a number of unconventional programming models have evolved, in particular the event-based model. These models are non-intuitive to programmers due to the introduction of unnecessary, non-intrinsic complexity. Component-based languages like Insense can eliminate much of this unnecessary complexity via the use of active components and synchronous channels. However, simply layering an Insense implementation over an existing event-based system, like TinyOS, while proving efficacy, is insufficiently space and time efficient for production use. The design and implementation of a new language-specific OS, InceOS, enables both space and time efficient programming of sensor networks using component-based languages like Insense

Optimizing Sensor Network Reprogramming via In-situ Reconfigurable Components

International audienceWireless reprogramming of sensor nodes is a critical requirement in long-lived Wireless Sensor Networks (WSNs) for several concerns, such as fixing bugs, upgrading the operating system and applications, and adapting applications behavior according to the physical environment. In such resource-poor platforms, the ability to efficiently delimit and reconfigure the necessary portion of sensor software--instead of updating the full binary image--is of vital importance. However, most of existing approaches in this field have not been widely adopted to date due to the extensive use of WSN resources or lack of generality. In this article, we therefore consider WSN programming models and run-time reconfiguration models as two interrelated factors and we present an integrated approach for addressing efficient reprogramming in WSNs. The middleware solution we propose, RemoWare, is characterized by mitigating the cost of post-deployment software updates on sensor nodes via the notion of in-situ reconfigurability and providing a component-based programming abstraction to facilitate the development of dynamic WSN applications. Our evaluation results show that RemoWare imposes a very low energy overhead in code distribution and component reconfiguration, and consumes approximately 6% of the total code memory on a TelosB sensor platform

The design of a generalised approach to the programming of systems of systems

The world's computing infrastructure is increasingly differentiating into self-contained sub-systems (e.g. Internet of Things installations, clouds, VANETs, ...), which are post-hoc composed to generate value-added functionality (“systems of systems”). Today, however, such system-of-systems composition is typically carried out in an ad-hoc and infrastructure-dependent manner, with obvious associated disadvantages. In this paper, we propose a generalised system-of-systems-oriented programming approach that enables programmers to manage the composition of systems without a need for intimate knowledge of their internals, and also facilitates dynamic and spontaneous system composition, as systems discover each other opportunistically in their environment

A Generic Component-based Approach for Programming, Composing and Tuning Sensor Software

International audienceWireless sensor networks (WSNs) are being extensively deployed today in various monitoring and control applications by enabling rapid deployments at low cost and with high flexibility. However, high-level software development is still one of the major challenges to wide-spread WSN adoption. The success of high-level programming approaches in WSNs is heavily dependent on factors such as ease of programming, code well-structuring, degree of code reusability, required software development effort and the ability to tune the sensor software for a particular application. Component-based programming has been recognized as an effective approach to satisfy such requirements. However, most of the componentization efforts in WSNs were ineffective due to various reasons, such as high resource demand or limited scope of use. In this article, we present Remora, a novel component-based approach to overcome the hurdles of WSN software implementation and configuration. Remora offers a well-structured programming paradigm that fits very well with resource limitations of embedded systems, including WSNs. Furthermore, the special attention to event handling in Remora makes our proposal more practical for embedded applications, which are inherently event-driven. More importantly, the mutualism between Remora and underlying system software promises a new direction towards separation of concerns in WSNs. This feature also offers a practical way to develop sensor middleware services which should be generic and developed close to the operating system. Additionally, it allows the customization of sensor software--deploying only application-required system-level services on nodes, instead of installing a fixed large system software image for any application. Our evaluation results show that the deployed Remora applications have an acceptable memory overhead and a negligible CPU cost compared with the state-of-the-art development models

Chargement dynamique par composants pour réseaux de capteurs adaptables

L'utilisation des réseaux de capteurs sans fil (RCSF) croît dans plusieurs domaines, dont celui des espaces intelligents. Dans un espace intelligent, les RCSF sont utilisés puisque les noeuds qui les composent se dissimulent dans l'environnement et consomment très peu d'énergie. Pour l'installation, la maintenance et la gestion des contextes, il est nécessaire de pouvoir reprogrammer un, noeud sans avoir à le redémarrer. Ce projet de recherche vise l'amélioration de la reprogrammation des RCSF en utilisant l'ingénierie logicielle basée sur les composants (ILBC). En utilisant un cadriciel hybride de composants et un format exécutable allégé, les composants dynamiques deviennent utilisables à moindres coûts. Les résultats obtenus lors de ces travaux ont été publiés dans un article de journal. Les travaux de ce projet se divisent en deux volets. Le premier volet est l'optimisation des cadriciels dynamiques de composants. Le problème est que ces derniers demandent trop de ressources et ne sont pas envisageables pour les RCSF. Afin de diminuer la surcharge en taille de l'utilisation de composants dynamiques, un concept de cadriciel hybride de composants' est proposé. Pour valider ce concept, le cadriciel NodeCom est créé et requiert aussi peu de mémoire que Contiki. NodeCom possède un noyau minimal qui est statique alors que les autres composants peuvent être statiques ou dynamiques. Le deuxième volet est l'optimisation de la reprogrammation adaptée aux RCSF avec l'ILBC. C'est en compressant. le format de fichiers exécutable qui contint les composants que la reprogrammation est optimisée. Le chargement dynamique utilisé est accéléré et la consommation énergétique du transfert de composants est diminuée. C'est le format ELF qui est modifié pour partager les composants dynamiques. Pour réduire sa taille, plusieurs sections et symboles peuvent être supprimés en raison des contraintes imposées par l'utilisation de l'ILBC. Puisque les RCSF utilisent majoritairement des microcontrôleurs 8 bits ou 16 bits, les métadonnées 32 bits du format ELF sont converties. La résultante de ces modifications est le format de composants ComELF qui permet d'obtenir des compressions de près de 50 %. À ce format, une description des composants est finalement ajoutée pour permettre une gestion automatique du chargement dynamique

Overlay virtualized wireless sensor networks for application in industrial internet of things : a review

Abstract: In recent times, Wireless Sensor Networks (WSNs) are broadly applied in the Industrial Internet of Things (IIoT) in order to enhance the productivity and efficiency of existing and prospective manufacturing industries. In particular, an area of interest that concerns the use of WSNs in IIoT is the concept of sensor network virtualization and overlay networks. Both network virtualization and overlay networks are considered contemporary because they provide the capacity to create services and applications at the edge of existing virtual networks without changing the underlying infrastructure. This capability makes both network virtualization and overlay network services highly beneficial, particularly for the dynamic needs of IIoT based applications such as in smart industry applications, smart city, and smart home applications. Consequently, the study of both WSN virtualization and overlay networks has become highly patronized in the literature, leading to the growth and maturity of the research area. In line with this growth, this paper provides a review of the development made thus far concerning virtualized sensor networks, with emphasis on the application of overlay networks in IIoT. Principally, the process of virtualization in WSN is discussed along with its importance in IIoT applications. Different challenges in WSN are also presented along with possible solutions given by the use of virtualized WSNs. Further details are also presented concerning the use of overlay networks as the next step to supporting virtualization in shared sensor networks. Our discussion closes with an exposition of the existing challenges in the use of virtualized WSN for IIoT applications. In general, because overlay networks will be contributory to the future development and advancement of smart industrial and smart city applications, this review may be considered by researchers as a reference point for those particularly interested in the study of this growing field

STiC -- A multi-atom non-LTE PRD inversion code for full-Stokes solar observations

The inference of the underlying state of the plasma in the solar chromosphere remains extremely challenging because of the nonlocal character of the observed radiation and plasma conditions in this layer. Inversion methods allow us to derive a model atmosphere that can reproduce the observed spectra by undertaking several physical assumptions. The most advanced approaches involve a depth-stratified model atmosphere described by temperature, line-of-sight velocity, turbulent velocity, the three components of the magnetic field vector, and gas and electron pressure. The parameters of the radiative transfer equation are computed from a solid ground of physical principles. To apply these techniques to spectral lines that sample the chromosphere, NLTE effects must be included in the calculations. We developed a new inversion code STiC to study spectral lines that sample the upper chromosphere. The code is based the RH synthetis code, which we modified to make the inversions faster and more stable. For the first time, STiC facilitates the processing of lines from multiple atoms in non-LTE, also including partial redistribution effects. Furthermore, we include a regularization strategy that allows for model atmospheres with a complex stratification, without introducing artifacts in the reconstructed physical parameters, which are usually manifested in the form of oscillatory behavior. This approach takes steps toward a node-less inversion, in which the value of the physical parameters at each grid point can be considered a free parameter. In this paper we discuss the implementation of the aforementioned techniques, the description of the model atmosphere, and the optimizations that we applied to the code. We carry out some numerical experiments to show the performance of the code and the regularization techniques that we implemented. We made STiC publicly available to the community.Comment: Accepted for publication in Astronomy & Astrophysic