Performance Comparison of the RPL and LOADng Routing Protocols in a Home Automation Scenario

RPL, the routing protocol proposed by IETF for IPv6/6LoWPAN Low Power and Lossy Networks has significant complexity. Another protocol called LOADng, a lightweight variant of AODV, emerges as an alternative solution. In this paper, we compare the performance of the two protocols in a Home Automation scenario with heterogenous traffic patterns including a mix of multipoint-to-point and point-to-multipoint routes in realistic dense non-uniform network topologies. We use Contiki OS and Cooja simulator to evaluate the behavior of the ContikiRPL implementation and a basic non-optimized implementation of LOADng. Unlike previous studies, our results show that RPL provides shorter delays, less control overhead, and requires less memory than LOADng. Nevertheless, enhancing LOADng with more efficient flooding and a better route storage algorithm may improve its performance

Distributed Simulation of Parallel Computers

We propose a method for emulating the behavior of your favorite MIMD computer on a network of workstations, so that programs written for the MIMD target can run on the distributed emulated version with just a recompilation. This is achieved by executing the computational parts as in the native run, with the message passing being simulated. The hardware of the target machine is simulated so that the behavior of the application is identical to a native run on the simulated computer with virtual timings and trace files. Moreover, our complexity analysis sets up the conditions required to achieve a good speedup as a function of the number of simulation hosts, the network latency and the granularity of the application

Réseaux de micro-contrôleurs à faible consommation d'énergie embarquant des capteurs : Premières expériences et développement d'une nouvelle interface paramétrable et programmable

This document is a technical report, dealing with the creation of a wireless sensor network, based on the 6LoWPAN standard using the Archrock system. It describes the implementation of Webaccess, an add-on interface to the Archrock web interface

Modeling and Dimensioning Ground Heat Exchangers Principles: Influence of the soil's thermal proprieties

International audienceIn the context of energy crisis and global warming, heating buildings with the solar energy stored in the soil rep- resents a very interesting alternative. Moreover, cooling buildings can also use the soil damping capacity. This paper presents our reflexion about the modeling and dimensioning of the ground heat exchanger part of ground-coupled heat pumps (GCHP). After a physical overview of the ground heat exchanger, we extract from analytical solutions practical consequences of the soil damping behavior and limits that provide guidelines for the dimensioning. We then question the default values of the numerical tools thermal parameters used for the simulation of GCHP. We illustrate this issue through a TRNSYS dynamic simulation of GCHP, demonstrating that soil's thermal parameters have a strong impact on the results. Finally, we give some perspectives for the determination of soil's characteristics in situ, but indirectly, thanks to geophysical prospection methods as ground penetrating radar, electromagnetic induction, or electrical resistivity tomography.Dans un contexte de crise e ́nerge ́tique et de re ́chauffement climatique, le chauffage des baˆtiments graˆce a` l'e ́nergie solaire stocke ́e dans le sol est un principe inte ́ressant. De plus, les sondes ge ́othermiques utilise ́es pour extraire la chaleur du sol permettent aussi de l'y re ́injecter, et donc de refroidir les baˆtiments graˆce a` l'inertie thermique du sol. Cet article pre ́sente nos re ́flexions sur la mode ́lisation et le dimensionnement des e ́changeurs thermiques en faible profondeur couple ́s a` des pompes a` chaleur (PAC ge ́othermique). Apre`s une pre ́sentation de la physique sous-jacente aux e ́changeurs thermiques et des me ́thodes de re ́solution analytiques et nume ́riques, nous soulignons l'importance des valeurs des parame`tres thermiques du sol utilise ́es par les outils nume ́riques pour simuler les PAC ge ́othermiques. Nous illustrons cette question a` partir de re ́sultats de simulation dynamique TRNSYS : ceux-ci sont fortement influence ́s par les valeurs de conductivite ́ thermique du sol. Enfin, nous pre ́sentons un e ́tat de l'art des mesures de ces parame`tres thermiques in situ et sugge ́rons quelques me ́thodes ge ́ophysiques pour les de ́terminer indirectement, parmi lesquelles le ge ́oradar, l'induction e ́lectromagne ́tique et la tomographie e ́lectrique. La forte empreinte de la teneur en eau sur la thermique des sols permettrait en effet d'estimer leurs caracte ́ristiques thermiques via des mesures de conductivite ́ e ́lectrique ou de permittivite ́ die ́lectrique, elles aussi relie ́es a` la teneur en eau du milieu

Efficient Block Cyclic Data Redistribution

Implementing linear algebra kernels on distributed memory parallel computers raises the problem of data distribution of matrices and vectors among the processors. Block-cyclic distribution seems to suit well for most algorithms. But one has to choose a good compromise for the size of the blocks (to achieve a good computation and communication efficiency and a good load balancing). This choice heavily depends on each operation, so it is essential to be able to go from one distribution to another very quickly. We present here the algorithms we implemented in the SCALAPACK library. A complexity study is made that proves the efficiency of our solution. Timing results on the Intel Paragon and the Cray T3D corroborates the results. We show the gain that can be obtained using the good data distribution with 3 numerical kernels and our redistribution routines

Exploiting Addresses Correlation to Maximize Lifetime of IPv6 Cluster-based WSNs

International audienceImproving the network lifetime is an important design criterion for wireless sensor networks. To achieve this goal, we propose in this paper a novel approach which applies source-coding on addresses in heterogeneous IPv6 Cluster-based wireless sensor network. We formulate the problem of maximiz- ing the network lifetime when Slepian-wolf coding is applied on addresses in network composed of line-powered and battery- powered sensors. This problem optimizes the placement of line- powered sensors to enable the battery-powered ones to exploit the addresses correlation and reduce the size of their emitted packets and thus improve the network lifetime. The numerical results show that a significant network lifetime improvement can be achieved (about 25% in typical scenario)

Stratégie de Placement des Puits Mobiles dans les Réseaux de Capteurs sans Fil pour Bâtiments

National audienceLe besoin des réseaux de capteurs sans fil croit très rapidement dans un large éventail d'applications industrielles. Parmi celles-ci se trouve l'observation, le suivi des données physiques et l'automatisation des bâtiments. Dans ces réseaux, un grand nombre de capteurs transmettent via multi sauts les données collectées vers le puits le plus proche. Les capteurs qui sont proches des puits épuisent leurs réserves d'énergie beaucoup plus rapidement que les capteurs distants car ils ont une charge de trafic très importante. Ceci est dû au fait qu'ils transmettent leurs propres données ainsi que les données des capteurs éloignés provoquant ainsi prématurément la fin de la durée de vie du réseau. Le déplacement périodique des puits permet de résoudre ce problème en distribuant la charge du trafic entre les capteurs et améliorer ainsi la durée de vie du réseau. Dans ce travail, nous proposons un nouvel algorithme qui détermine le positionnement de plusieurs puits mobiles dans un réseau large échelle afin d'augmenter la durée de vie du réseau. Son principe se base sur le déplacement régulier des puits vers les capteurs distants qui ont le plus grand nombre de sauts à faire pour atteindre le puits le plus proche. Nous avons évalué les performances de notre solution par des simulations et comparé avec d'autres stratégies. Les résultats montrent que notre solution améliore considérablement la durée de vie du réseau et équilibre notablement la consommation d'énergie entre les nœuds. Ces résultats sont très utiles pour le déploiement réel de réseaux de capteurs sans fil au sein des bâtiments

Multiple Mobile Sinks Positioning in Wireless Sensor Networks for Buildings

Best Paper AwardInternational audienceReal deployment of wireless sensor networks inside build- ings is a very challenging. In fact, in such networks, a large number of small sensor devices suffer from limited energy supply. These sensors have to observe and monitor their in-door environment, and then to report the data collected to a nearest information collector, referred to as the sink node. Sensor nodes which are far away from the sink relay their data via multiple hops to reach the sink. This way of communication makes the sensors near the sink deplete their energy much faster than distant nodes because they carry heavier traffic. So what is known as a hole appears around the sink and prevents distant nodes to send their data. Consequently the network lifetime ends prematurely. One efficient solution for this problem is to relocate sinks. In this work, we aim to find the best way to relocate sinks by determining their optimal locations and the duration of their sojourn time. So, we propose an Integer Linear Programming for multiple mobile sinks which directly maximizes the network lifetime instead of minimizing the energy consumption or maximizing the residual energy, which is what was done in previous solutions. Simulations results show that with our solution, the network lifetime is extended and the energy depletion is more balanced among the nodes. We also show that relocating mobile sinks inside a whole network is more efficient than relocating mobile sinks inside different clusters and we can achieve almost 52 % network lifetime improvement in our experiments

Sinks Mobility Strategy in IPv6-based WSNs for Network Lifetime Improvement

International audienceThis paper investigates the sinks mobility in IPv6- based wireless sensors networks and specially in the new IETF proposed protocol RPL (Routing Protocol for Low power and Lossy Networks). We also show that even the mobility of sinks is not an explicit design criteria, the use of mobile sinks improves the network lifetime. In this work, we propose a new distributed and weighted moving strategy for sinks in RPL. We compared our proposed mobility approach with different others strategies. The results show that our proposed mobility approach notably balances the network load which leads to a significant network lifetime gain in large scale network

Parametric Sensitivity Study and Optimization of the SDHW and PV Subsystems in an Energy Positive House

International audienceThis study presents a parametric sensitivity analysis of the dynamic simulation of the Solar Domestic Hot Water (SDHW) and Photovoltaic (PV) solar systems in an energy positive house. The optimized parameters concern the solar collectors, the storage tank and the fluid circulator. Significant gains are obtained on most of the parameters which allows for a better solar fraction with the SDHW. The energy need for the DHW auxiliary and pump is divided by three with a load scenario corresponding to a family of four. Moreover, we extended the study to the PV system to provides the best repartition option between thermal and PV panels on the solar roof. This maximizes the opportunity of generating surplus electricity, sold back to the power grid.Nous pre ́sentons une e ́tude de sensibilite ́ parame`trique sur la simulation nume ́rique dynamique des syste`mes d'ECS solaire (CESI) et PV dans une maison a` bilan d'e ́nergie positif. Les parame`tres d'optimisation concernent les capteurs, le ballon de stockage et le circulateur. Graˆce a` cette e ́tude, des gains important sont obtenus pour chacun des parame`tres e ́tudie ́s. Nous re ́duisons d'un facteur trois les besoins e ́nerge ́tiques annuels en appoint et circulation du syste`me initial dans un sce ́nario de charge correspondant a` une famille moyenne de quatre personnes. Nous poursuivons l'e ́tude avec le PV afin de de ́duire la re ́partition optimale de la surface du toit solaire entre les capteurs thermique et PV. Notre re ́sultat permet de produire plus d'e ́lectricite ́ pour la revente au re ́seau