Sara Blanc

An Ultra-Low Power and Flexible Acoustic Modem Design to Develop Energy-Efficient Underwater Sensor Networks

This paper is focused on the description of the physical layer of a new acoustic modem called ITACA. The modem architecture includes as a major novelty an ultra-low power asynchronous wake-up system implementation for underwater acoustic transmission that is based on a low-cost off-the-shelf RFID peripheral integrated circuit. This feature enables a reduced power dissipation of 10 μW in stand-by mode and registers very low power values during reception and transmission. The modem also incorporates clear channel assessment (CCA) to support CSMA-based medium access control (MAC) layer protocols. The design is part of a compact platform for a long-life short/medium range underwater wireless sensor network.

RFID Based Acoustic Wake-Up System for Underwater Sensor Networks

This paper presents a new Acoustic-Triggered Wake-Up system specially useful to Underwater Wireless Sensor Networks built with low-power consumption architectures. The work includes both the wake-up system description and a comparison with previous works carried out under similar features. These comparisons demonstrate the energy benefits of this new system which requires no additional hardware within the transmission and a single but efficient AT-WUp module in the reception.

WSN with energy-harvesting: modeling and simulation based on a practical architecture using real radiation levels

This paper presents a new energy-harvesting provider for ns-3 simulation tool. The provider model assumes solar energy harvesting and super-capacitor storage to supply power to a Wireless Sensor Node. Super-capacitors charge and discharge is dynamically estimated based on both power consumption in the node and solar radiation levels. On one hand, super-capacitors voltage level is refreshed within each radio mode change. However, because a radio mode can be longer than few milliseconds, refreshments are also time schedule. On the other hand, solar radiation data in CSV format (comma-separated values) can be downloaded from public meteorological data bases. The model incorporates these input data being possible to simulate from one minute to weeks or months using real radiation curves observed in a specific world location at a year period. The research presented in this paper will be very useful for the study and development of energy-efficient algorithms with energy-neutral operation to build everlasting Wireless Sensor Networks.

RFID-based wake-up system for wireless sensor networks

A critical issue of Wireless Sensor Networks circuits is energy management. This work presents a Radio-Triggered Wake-Up solution designed and developed for WSN based systems. The proposed circuit manages, in a simple and efficient way, node switching between sleep mode and both receiving or transmitting active modes. It uses a HW hearing circuit, which lowers power consumption and avoids extra processing on the main microcontroller. The weak-up is selective with predefined recognition patterns without the microcontroller intervention. Furthermore, it is tiny in size, and the whole circuit is suitable for single CMOS chip integration. The circuit has been tested to demonstrate the Wake- Up proposal worthiness. With only 8.7 microwatts of power consumption (@ 3.0 Vdc) the system successfully Wake-Up nodes up to 15 meters away from the transmission source. This performance improves solutions presented in previous research works.

SIVEH: Numerical Computing Simulation of Wireless Energy-Harvesting Sensor Nodes

The paper presents a numerical energy harvesting model for sensor nodes, SIVEH (Simulator I–V for EH), based on I–V hardware tracking. I–V tracking is demonstrated to be more accurate than traditional energy modeling techniques when some of the components present different power dissipation at either different operating voltages or drawn currents. SIVEH numerical computing allows fast simulation of long periods of time—days, weeks, months or years—using real solar radiation curves. Moreover, SIVEH modeling has been enhanced with sleep time rate dynamic adjustment, while seeking energy-neutral operation. This paper presents the model description, a functional verification and a critical comparison with the classic energy approach.

Wireless sensor network with energy harvesting: modeling and simulation based on a practical architecture using real radiation levels

This paper presents a new energy‐harvesting model for a network simulator that implements super‐capacitor energy storage with solar energy‐harvesting recharge. The model is easily extensible, and other energy‐harvesting systems, or different energy storages, can be further developed. Moreover, code can be conveniently reused as the implementation is entirely uncoupled from the radio and node models. Real radiation data are obtained from available online databases in order to dynamically calculate super‐capacitor charge and discharge. Such novelty enables the evaluation of energy evolution on a network of sensor nodes at various physical world locations and during different seasons. The model is validated against a real and fully working prototype, and good result correlation is shown. Furthermore, various experiments using the ns‐3 simulator were conducted, demonstrating the utility of the model in assisting the research and development of the deployment of everlasting wireless sensor networks. Copyright

A fault hypothesis study on the TTP/C using VHDL-based and pin-level fault injection techniques

Fault injection techniques are frequently used for validating dependable systems. VHDL-based techniques are good resources that support fault injection with many advantages such as a high level of accessibility, controllability and precision. This paper presents the results obtained with a VHDL-based tool (VFIT) injecting single and multiple faults at pin-level in a TTP/C model. The study is focused on the fault hypothesis of a modelled communications protocol based on the Time-Triggered Architecture. Results are analysed and compared with the experiments carried out in the real prototyped system with a pin-level fault injection tool (AFIT). Conclusions strengthen the usability of VHDL-based fault injection tools and reveal technique weaknesses.

Generic Design and Automatic Deployment of NMR Strategies on HW Cores

Hardware fault tolerance is a requirement even for noncritical applications, since unexpected failures may damage the reputation of manufacturers and limit the acceptance of their products. However, current practices for the design and deployment of hardware redundancy techniques remain in practice specific (defined on a case-per-case basis) and mostly manual. This paper addresses the challenging problems of (i) engineering NMR strategies in a generic way, and (ii) automating their deployment. This approach relies on metaprogramming to specify NMR mechanisms and open compilers to automatically deploy such mechanisms on the selected hardware core. Fault injection complements that approach by providing the means to (i) determine the best core for replication, and (ii) check the effectiveness of the deployed NMR strategy. A PIC microcontroller is used as case study to exemplify the approach and show its feasibility.

A Decentralized Wireless Solution to Monitor and Diagnose PV Solar Module Performance Based on Symmetrized-Shifted Gompertz Functions

This paper proposes and assesses an integrated solution to monitor and diagnose photovoltaic (PV) solar modules based on a decentralized wireless sensor acquisition system. Both DC electrical variables and environmental data are collected at PV module level using low-cost and high-energy efficiency node sensors. Data is real-time processed locally and compared with expected PV module performances obtained by a PV module model based on symmetrized-shifted Gompertz functions (as previously developed and assessed by the authors). Sensor nodes send data to a centralized sink-computing module using a multi-hop wireless sensor network architecture. Such integration thus provides extensive analysis of PV installations, and avoids off-line tests or post-processing processes. In comparison with previous approaches, this solution is enhanced with a low-cost system and non-critical performance constraints, and it is suitable for extensive deployment in PV power plants. Moreover, it is easily implemented in existing PV installations, since no additional wiring is required. The system has been implemented and assessed in a Spanish PV power plant connected to the grid. Results and estimations of PV module performances are also included in the paper.

Modelling and Simulation of Underwater Low-Power Wake-Up Systems

Underwater Wireless Sensor Networks (UWSN) have become an important area of research due to its many possible applications. One example are the long-term monitoring applications were the nodes only need to be awake during a small fraction of time. This kind of applications can greatly benefit from low-power, wake-up systems. However, despite the fact that the simulations can greatly improve the development time of new algorithms and features, optimizing their performance, up until today there is no wake-up system model available.