RPL Routing Protocol a case study: Precision agriculture

International audienceThe routing protocol for low power and lossy network (RPL) was designed in the ROLL working group at IETF since the year of 2008. Until the latest version of draft 19 released, this protocol algorithms and its four application scenario, such as home automation, industrial control, urban environment and building automation, have been nearly grounded. However, it is still very difficult to find effective approaches to simulate and evaluate RPL's behavior and other extensions of its application. In this paper, first we provide a brief presentation of the RPL protocol including two case studies ContikiRPL and TinyRPL, and an initial simulation experiment results obtained from the RPL capable COOJA simulator and its developed module. Second we then focus on the utilization of this protocol in the precision agriculture area and propose our dedicated instances hybrid network architecture to meet the specific requirement of this application. As a conclusion, we summarized our ongoing work and future solutions of the current technology issues

A context-aware tool-set for routing-targeted mutual configuration and optimization of LLNs through bridging virtual and physical worlds

International audienceIn the history of the WSN, unexpected routing behaviors is always a main issue of the large scale WSN deployments. Considering the high cost of building a real deployment, network simulators are often used in this domain. However, the original problem is still not solved although the era of IoT has been coming. A new concept of LLN is emerging. We realize that, no matter how wonderful the results from the simulation scenarios and thorough testing, the problems, such as bad performance or even severe system failures due to suboptimal routing path, would still happen in the real-world system. Our context-aware tool-set can help to build the simulation topology which is more close to the real network through mapping a serial routing metrics defined by IEFT ROLL working group and the link situation of the actual network. We believe our suggestion of bridging virtual and physical worlds reflected on our proposed tool-set could conduct more precise routing-targeted simulations. Moreover, by close-loop method, the knowledge and analyzed simulation results can lead us to improve the routing topology of the deployed LLN

A RPL based adaptive and scalable data-collection protocol module for NS-3 simulation platform

International audienceThis paper presents data-collection protocol framework based on RPL (IPv6 Routing Protocol for Low Power and Lossy Networks) for NS-3 (Network Simulator 3) simulation platform. Its design, implementation, simple examples of operations and evaluations will also be demonstrated. The conclusions and future developments are located in the final part of this paper

Extension of the Semantic Sensor Network Ontology for Wireless Sensor Networks: The Stimulus-WSNnode-Communication Pattern

International audienceWireless Sensor Networks (WSN) are designed to collect large amounts of heterogeneous data to monitor environmental phenomenon. Our aim is to adapt WSN nodes communication to their context, in order to optimize the lifetime of the network. Our description of context and WSN characteristics are based on ontologies. Based upon a critical analysis of existing ontologies which formalize the WSN domain, we determine that the Semantic Sensor Network (SSN) ontology is the most suitable to represent the WSN issues. However, as the communication data policy is not characterized either by SSN or by other ontologies, we propose to enrich the SSN ontology with a new pattern describing communication. In this paper, we will first integrate the different concepts related to WSN in the SSN ontology and then we will use the resulting ontology, called Wireless Semantic Sensor Network ontology, in an agri-environmental scenario to illustrate the interest of our approach

A new management method for wireless sensor networks

International audienceThe Wireless Sensor Networks (WSN) with their constant evolution, need new management methods to be monitored efficiently by taking into account the context and their constraints such as energy consumption, reliability and remote monitoring. WSN has diverse application domains: smart home, smart care, environmental data collection etc. In order to manage a large scale WSN, several Wireless sensor network Management Tools (WMTs) are developed. Some of them use SNMP protocol like because it is impossible to implement the full compliance classical SNMP standard on each wireless sensor node. Therefore, it is important to develop a new WMT with a restricted SNMP standard dedicated to WSN applications. In this paper, we present a new WMT named LiveNCM: LiveNode Non invasive Context-aware, and modular Management tool. LiveNCM is divided into two main parts: one is centralized on the fixed network structure and another one, distributed on each node. Each part introduces the concept of non-invasive context-aware to reduce data exchanges and diagnoses the wireless sensor node state with few messages. Moreover, nodes are based on a configurable modular architecture enables to adapt to an application and to a local node constraints. LiveNCM is implemented on the LiveNode platform to validate the energy consumption and on a UNIX system to validate the adopted SNMP sub-agent. Ultimately, a decreasing data exchange and an improvement in the energy consumption in the entire WSN were observed. An implementation of the proposed management method is presented

Cooperative inter-vehicle communication protocol with low cost differential GPS

This paper describes a cooperative MANET protocol dedicated to intelligent transport systems, named CIVIC (Communication Inter Véhicule Intelligente et Coopérative). The CIVIC protocol is an auto-configuration inter-vehicle communication protocol, which supports adhoc and infrastructure networks, contains reactive and proactive routing components, and adapts different wireless standards. It is a context-aware protocol reacting to vehicle status, road traffic, and geographic environment. It supports location-based communication. To improve the accuracy of GPS, it integrates a localization solution called LCD-GPS (Low Cost Differential GPS). It has been implemented and experimented on the LiveNode sensor developed by our lab. At the end of this paper, an application project MobiPlus is introduced

Final State Rescattering and Color-suppressed \bar B^0-> D^{(*)0} h^0 Decays

The color-suppressed \bar B^0-> D^{(*)0}\pi^0, D^{(*)0}\eta, D^0\omega decay modes have just been observed for the first time. The rates are all larger than expected, hinting at the presence of final state interactions. Considering \bar B^0-> D^{(*)0}\pi^0 mode alone, an elastic D^{(*)}\pi -> D^{(*)}\pi rescattering phase difference \delta \equiv \delta_{1/2} - \delta_{3/2} \sim 30^\circ would suffice, but the \bar B^0-> D^{(*)0}\eta, D^0\omega modes compel one to extend the elastic formalism to SU(3) symmetry. We find that a universal a_2/a_1=0.25 and two strong phase differences 20^\circ \sim \theta < \delta < \delta^\prime \sim 50^\circ can describe both DP and D^*P modes rather well; the large phase of order 50^\circ is needed to account for the strength of {\it both} the D^{(*)0}\pi^0 and D^{(*)0}\eta modes. For DV modes, the nonet symmetry reduces the number of physical phases to just one, giving better predictive power. Two solutions are found. We predict the rates of the \bar B^0-> D^{+}_s K^-, D^{*+}_s K^-, D^0\rho^0, D^+_s K^{*-} and D^0\phi modes, as well as \bar B^0-> D^{0}\bar K^0, D^{*0}\bar K^0, D^{0}\bar K^{*0} modes. The formalism may have implications for rates and CP asymmetries of charmless modes.Comment: REVTeX4, 18 pages, 5 figures, to appear in Phys. Rev.

Wireless multimedia sensor network for plant disease detections

International audienceTo minimize pesticide use it is necessary to detect at the early stage the present of plant disease and perform local treatment instead of global systematic treatment. To achieve this goal, one of the techniques may be used is image processing through the deployment of WMSN in the cultivated field. However, transmitting massive image data wirelessly will increase significantly network traffic and particularly energy consumption. In this paper, we propose a plant disease detection approach which is designed to run on the resource-constrained WMSN nodes. Through the analysis of plant images acquired by the node, this new approach is able to make a preliminary local decision on the health condition of the plant and determine the necessity of sending back images to the control centre for further inspection, thus improving the efficiency of the monitoring network. The complete method includes image segmentation based on both color and shape, and uses 2D histogram as the feature for classification. Experiments on the plant images with nutrient deficiency symptoms show the classification accuracy of the new method reaches 87.5%

Size dependence of selectively oxidized VCSEL transverse-mode structure

The performance of vertical cavity surface emitting lasers (VCSELs) has improved greatly in recent years. Much of this improvement can be attributed to the use of native oxide layers within the laser structure, providing both electrical and optical transverse confinement. Understanding this optical confinement will be vital for the future realization of yet smaller lasers with ultralow threshold currents. Here the authors report the spectral and modal properties of small (0.5 {micro}m to 5 {micro}m current aperture) VCSELs and identify Joule heating as a dominant effect in the resonator properties of the smallest lasers

Coupled resonator vertical cavity laser diodes

For many applications, the device performance of edge emitting semiconductor lasers can be significantly improved through the use of multiple section devices. For example, cleaved coupled cavity (C3) lasers have been shown to provide single mode operation, wavelength tuning, high speed switching, as well as the generation of short pulses via mode-locking and Q-switching [1]. Using composite resonators within a vertical cavity laser opens up new possibilities due to the unique ability to tailor the coupling between the monolithic cavities, incorporate passive or active resonators which are spectrally degenerate or detuned, and to fabricate these devices in 2-dimensional arrays. Composite resonator vertical cavity lasers (CRVCL) have been examined using optical pumping and electrical injection [2-5]. We report on CRVCL diodes and show that efficient modulation of the laser emission can be achieved by either forward or reverse biasing the passive cavity within a CRVCL