Antonio J. Sánchez

Underwater Acoustic Wireless Sensor Networks: Advances and Future Trends in Physical, MAC and Routing Layers

This survey aims to provide a comprehensive overview of the current research on underwater wireless sensor networks, focusing on the lower layers of the communication stack, and envisions future trends and challenges. It analyzes the current state-of-the-art on the physical, medium access control and routing layers. It summarizes their security threads and surveys the currently proposed studies. Current envisioned niches for further advances in underwater networks research range from efficient, low-power algorithms and modulations to intelligent, energy-aware routing and medium access control protocols.

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

Handling for Micro-manufacturing

At a micro-manufacturing facility, the handling process includes transporting components from one location to another, orientation control, and sorting. It is essential that the components are presented in a specific position, are facing the right direction, and are at a suitable rate at all workstations. Automated positioning at the meso-scale is easily solved using conventional closed-loop control and a variety of sensors but when the size of the components decreases, handling becomes the bottleneck in the fabrication process. The aim of this chapter is to emphasize the importance of the handling process in micro-manufacturing, compared to conventional manufacturing at a meso-scale.

Measurement and Modeling of Narrowband Channels for Ultrasonic Underwater Communications.

Underwater acoustic sensor networks are a promising technology that allow real-time data collection in seas and oceans for a wide variety of applications. Smaller size and weight sensors can be achieved with working frequencies shifted from audio to the ultrasonic band. At these frequencies, the fading phenomena has a significant presence in the channel behavior, and the design of a reliable communication link between the network sensors will require a precise characterization of it. Fading in underwater channels has been previously measured and modeled in the audio band. However, there have been few attempts to study it at ultrasonic frequencies. In this paper, a campaign of measurements of ultrasonic underwater acoustic channels in Mediterranean shallow waters conducted by the authors is presented. These measurements are used to determine the parameters of the so-called κ-μ shadowed distribution, a fading model with a direct connection to the underlying physical mechanisms. The model is then used to evaluate the capacity of the measured channels with a closed-form expression.

Predicting Gilthead Sea Bream (Sparus aurata) Freshness by a Novel Combined Technique of 3D Imaging and SW-NIR Spectral Analysis

A technique that combines the spatial resolution of a 3D structured-light (SL) imaging system with the spectral analysis of a hyperspectral short-wave near infrared system was developed for freshness predictions of gilthead sea bream on the first storage days (Days 0–6). This novel approach allows the hyperspectral analysis of very specific fish areas, which provides more information for freshness estimations. The SL system obtains a 3D reconstruction of fish, and an automatic method locates gilthead’s pupils and irises. Once these regions are positioned, the hyperspectral camera acquires spectral information and a multivariate statistical study is done. The best region is the pupil with an R2 of 0.92 and an RMSE of 0.651 for predictions. We conclude that the combination of 3D technology with the hyperspectral analysis offers plenty of potential and is a very promising technique to non destructively predict gilthead freshness.