Sensors

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25 pages, 1219 KiB

Open AccessArticle

Active Learning for Efficient Soil Monitoring in Large Terrain with Heterogeneous Sensor Network

by Hui Chen and Ju Wang

Sensors 2023, 23(5), 2365; https://doi.org/10.3390/s23052365 - 21 Feb 2023

Cited by 1 | Viewed by 1436

Soils are a complex ecosystem that provides critical services, such as growing food, supplying antibiotics, filtering wastes, and maintaining biodiversity; hence monitoring soil health and domestication is required for sustainable human development. Low-cost and high-resolution soil monitoring systems are challenging to design and [...] Read more.

Soils are a complex ecosystem that provides critical services, such as growing food, supplying antibiotics, filtering wastes, and maintaining biodiversity; hence monitoring soil health and domestication is required for sustainable human development. Low-cost and high-resolution soil monitoring systems are challenging to design and build. Compounded by the sheer size of the monitoring area of interest and the variety of biological, chemical, and physical parameters to monitor, naive approaches to adding or scheduling more sensors will suffer from cost and scalability problems. We investigate a multi-robot sensing system integrated with an active learning-based predictive modeling technique. Taking advantage of advances in machine learning, the predictive model allows us to interpolate and predict soil attributes of interest from the data collected by sensors and soil surveys. The system provides high-resolution prediction when the modeling output is calibrated with static land-based sensors. The active learning modeling technique allows our system to be adaptive in data collection strategy for time-varying data fields, utilizing aerial and land robots for new sensor data. We evaluated our approach using numerical experiments with a soil dataset focusing on heavy metal concentration in a flooded area. The experimental results demonstrate that our algorithms can reduce sensor deployment costs via optimized sensing locations and paths while providing high-fidelity data prediction and interpolation. More importantly, the results verify the adapting behavior of the system to the spatial and temporal variations of soil conditions. Full article

(This article belongs to the Special Issue Use Wireless Sensor Networks for Environmental Applications)

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18 pages, 938 KiB

Open AccessArticle

A Survey on the Security Challenges of Low-Power Wireless Communication Protocols for Communicating Concrete in Civil Engineerings

by Gaël Loubet, Eric Alata, Alexandru Takacs and Daniela Dragomirescu

Sensors 2023, 23(4), 1849; https://doi.org/10.3390/s23041849 - 07 Feb 2023

Cited by 3 | Viewed by 1635

Abstract

With the increase in low-power wireless communication solutions, the deployment of Wireless Sensor Networks is becoming usual, especially to implement Cyber-Physical Systems. These latter can be used for Structural Health Monitoring applications in critical environments. To ensure a long-term deployment, battery-free and energy-autonomous [...] Read more.

With the increase in low-power wireless communication solutions, the deployment of Wireless Sensor Networks is becoming usual, especially to implement Cyber-Physical Systems. These latter can be used for Structural Health Monitoring applications in critical environments. To ensure a long-term deployment, battery-free and energy-autonomous wireless sensors are designed and can be powered by ambient energy harvesting or Wireless Power Transfer. Because of the criticality of the applications and the limited resources of the nodes, the security is generally relegated to the background, which leads to vulnerabilities in the entire system. In this paper, a security analysis based on an example: the implementation of a communicating reinforced concrete using a network of battery-free nodes; is presented. First, the employed wireless communication protocols are presented in regard of their native security features, main vulnerabilities, and most usual attacks. Then, the security analysis is carried out for the targeted implementation, especially by defining the main hypothesis of the attack and its consequences. Finally, solutions to secure the data and the network are compared. From a global point-of-view, this security analysis must be initiated from the project definition and must be continued throughout the deployment to allow the use of adapted, updatable and upgradable solutions. Full article

(This article belongs to the Special Issue Use Wireless Sensor Networks for Environmental Applications)

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22 pages, 6862 KiB

Open AccessArticle

Machine-Learning-Based LOS Detection for 5G Signals with Applications in Airport Environments

by Palihawadana A. D. Nirmal Jayawardana, Hadeel Obaid, Taylan Yesilyurt, Bo Tan and Elena Simona Lohan

Sensors 2023, 23(3), 1470; https://doi.org/10.3390/s23031470 - 28 Jan 2023

Cited by 5 | Viewed by 2212

Abstract

The operational costs of the advanced Air Traffic Management (ATM) solutions are often prohibitive in low- and medium-sized airports. Therefore, new and complementary solutions are currently under research in order to take advantage of existing infrastructure and offer low-cost alternatives. The 5G signals [...] Read more.

The operational costs of the advanced Air Traffic Management (ATM) solutions are often prohibitive in low- and medium-sized airports. Therefore, new and complementary solutions are currently under research in order to take advantage of existing infrastructure and offer low-cost alternatives. The 5G signals are particularly attractive in an ATM context due to their promising potential in wireless positioning and sensing via Time-of-Arrival (ToA) and Angle-of-Arrival (AoA) algorithms. However, ToA and AoA methods are known to be highly sensitive to the presence of multipath and Non-Line-of-Sight (NLOS) scenarios. Yet, LOS detection in the context of 5G signals has been poorly addressed in the literature so far, to the best of the Authors’ knowledge. This paper focuses on LOS/NLOS detection methods for 5G signals by using both statistical/model-driven and data-driven/machine learning (ML) approaches and three challenging channel model classes widely used in 5G: namely Tapped Delay Line (TDL), Clustered Delay Line (CDL) and Winner II channel models. We show that, with simulated data, the ML-based detection can reach between 80% and 98% detection accuracy for TDL, CDL and Winner II channel models and that TDL is the most challenging in terms of LOS detection capabilities, as its richness of features is the lowest compared to CDL and Winner II channels. We also validate the findings through in-lab measurements with 5G signals and Yagi and 3D-vector antenna and show that measurement-based detection probabilities can reach 99–100% with a sufficient amount of training data and XGBoost or Random Forest classifiers. Full article

(This article belongs to the Special Issue Use Wireless Sensor Networks for Environmental Applications)

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30 pages, 7979 KiB

Open AccessArticle

An Inexpensive Unmanned Aerial Vehicle-Based Tool for Mobile Network Output Analysis and Visualization

by Vittorio Buggiani, Julio César Úbeda Ortega, Guillermo Silva, Jesús Rodríguez-Molina and Diego Vilca

Sensors 2023, 23(3), 1285; https://doi.org/10.3390/s23031285 - 23 Jan 2023

Viewed by 1420

Abstract

Usage of Unmanned Aerial Vehicles (UAVs) for different tasks is widespread, as UAVs are affordable, easy to manoeuvre and versatile enough to execute missions in a reliable manner. However, there are still fields where UAVs play a minimal role regardless of their possibilities. [...] Read more.

Usage of Unmanned Aerial Vehicles (UAVs) for different tasks is widespread, as UAVs are affordable, easy to manoeuvre and versatile enough to execute missions in a reliable manner. However, there are still fields where UAVs play a minimal role regardless of their possibilities. One of these application domains is mobile network testing and measurement. Currently, the procedures used to measure the main parameters of mobile networks in an area (such as power output or its distribution in a three-dimensional space) rely on a team of specialized people performing measurements with an array of tools. This procedure is significantly expensive, time consuming and the resulting outputs leave a higher degree of precision to be desired. An open-source UAV-based Cyber-Physical System is put forward that, by means of the Galileo satellite network, a Mobile Data Acquisition System and a Graphical User Interface, can quickly retrieve reliable data from mobile network signals in a three-dimensional space with high accuracy for its visualization and analysis. The UAV tested flew at 40.43 latitude and −3.65 longitude degrees as coordinates, with an altitude over sea level of around 600–800 m through more than 40 mobile network cells and signal power displayed between −75 and −113 decibels. Full article

(This article belongs to the Special Issue Use Wireless Sensor Networks for Environmental Applications)

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19 pages, 554 KiB

Open AccessArticle

Computation Offloading Game for Multi-Channel Wireless Sensor Networks

by Heng-Cheng Hu and Pi-Chung Wang

Sensors 2022, 22(22), 8718; https://doi.org/10.3390/s22228718 - 11 Nov 2022

Cited by 5 | Viewed by 1220

Abstract

Computation offloading for wireless sensor devices is critical to improve energy efficiency and maintain service delay requirements. However, simultaneous offloadings may cause high interferences to decrease the upload rate and cause additional transmission delay. It is thus intuitive to distribute wireless sensor devices [...] Read more.

Computation offloading for wireless sensor devices is critical to improve energy efficiency and maintain service delay requirements. However, simultaneous offloadings may cause high interferences to decrease the upload rate and cause additional transmission delay. It is thus intuitive to distribute wireless sensor devices in different channels, but the problem of multi-channel computation offloading is NP-hard. In order to solve this problem efficiently, we formulate the computation offloading decision problem as a decision-making game. Then, we apply the game theory to address the problem of allowing wireless sensor devices to make offloading decisions based on their own interests. In the game theory, not only are the data size of wireless sensor devices and their computation capability considered but the channel gain of each wireless sensor device is also included to improve the transmission rate. The consideration could evenly distribute wireless sensor devices to different channels. We prove that the proposed offloading game is a potential game, where the Nash equilibrium exists in each game after all device states converge. Finally, we extensively evaluate the performance of the proposed algorithm based on simulations. The simulation results demonstrate that our algorithm can reduce the number of iterations to achieve Nash equilibrium by 16%. Moreover, it improves the utilization of each channel to effectively increase the number of successful offloadings and lower the energy consumption of wireless sensor devices. Full article

(This article belongs to the Special Issue Use Wireless Sensor Networks for Environmental Applications)

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29 pages, 1472 KiB

Open AccessArticle

Rule-Driven Forwarding for Resilient WSN Infrastructures

by Pawel Gburzynski and Ioanis Nikolaidis

Sensors 2022, 22(22), 8708; https://doi.org/10.3390/s22228708 - 11 Nov 2022

Viewed by 984

Abstract

We present a simple, robust, ad hoc forwarding scheme for small-footprint, low-cost wireless sensor networks (WSNs) and discuss some of its features from the viewpoint of resilience. The class of applications shaping the resilience requirements for our discussion covers temporary, and possibly disposable [...] Read more.

We present a simple, robust, ad hoc forwarding scheme for small-footprint, low-cost wireless sensor networks (WSNs) and discuss some of its features from the viewpoint of resilience. The class of applications shaping the resilience requirements for our discussion covers temporary, and possibly disposable deployments of potentially massive populations of sensing nodes to assist in the management of emergency missions, including the management of the effects from natural or man-made disasters. Our goal is to make the network resistant to failures of any of its fragments, which may result from the network’s intended modus operandi or from intentional malicious attempts at crippling its function, while keeping the cost and footprint of the devices at the absolute minimum. Full article

(This article belongs to the Special Issue Use Wireless Sensor Networks for Environmental Applications)

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15 pages, 480 KiB

Open AccessArticle

Optimal User Scheduling in Multi Antenna System Using Multi Agent Reinforcement Learning

by Muddasar Naeem, Antonio Coronato, Zaib Ullah, Sajid Bashir and Giovanni Paragliola

Sensors 2022, 22(21), 8278; https://doi.org/10.3390/s22218278 - 28 Oct 2022

Cited by 4 | Viewed by 1252

Abstract

Multiple Input Multiple Output (MIMO) systems have been gaining significant attention from the research community due to their potential to improve data rates. However, a suitable scheduling mechanism is required to efficiently distribute available spectrum resources and enhance system capacity. This paper investigates [...] Read more.

Multiple Input Multiple Output (MIMO) systems have been gaining significant attention from the research community due to their potential to improve data rates. However, a suitable scheduling mechanism is required to efficiently distribute available spectrum resources and enhance system capacity. This paper investigates the user selection problem in Multi-User MIMO (MU-MIMO) environment using the multi-agent Reinforcement learning (RL) methodology. Adopting multiple antennas’ spatial degrees of freedom, devices can serve to transmit simultaneously in every time slot. We aim to develop an optimal scheduling policy by optimally selecting a group of users to be scheduled for transmission, given the channel condition and resource blocks at the beginning of each time slot. We first formulate the MU-MIMO scheduling problem as a single-state Markov Decision Process (MDP). We achieve the optimal policy by solving the formulated MDP problem using RL. We use aggregated sum-rate of the group of users selected for transmission, and a

20 %

higher sum-rate performance over the conventional methods is reported. Full article

(This article belongs to the Special Issue Use Wireless Sensor Networks for Environmental Applications)

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18 pages, 668 KiB

Open AccessArticle

Reducing Operational Expenses of LoRaWAN-Based Internet of Remote Things Applications

by Mariano Finochietto, Rodrigo Santos, Sergio F. Ochoa and Roc Meseguer

Sensors 2022, 22(20), 7778; https://doi.org/10.3390/s22207778 - 13 Oct 2022

Cited by 6 | Viewed by 1582

Abstract

LoRaWAN has become the most widely used low-power wide-area network technology to implement monitoring solutions based on the Internet of remote things (IoRT) paradigm. Typically, these solutions interconnect remote sensing areas and data processing infrastructure located in urban centers. The operation expenses of [...] Read more.

LoRaWAN has become the most widely used low-power wide-area network technology to implement monitoring solutions based on the Internet of remote things (IoRT) paradigm. Typically, these solutions interconnect remote sensing areas and data processing infrastructure located in urban centers. The operation expenses of these solutions depend mainly on the traffic sent through the network backhaul, i.e., the link that connects the remote sensing area and the urban area where the data are usually processed and stored. This service is provided by telecommunication companies and represents the main operation cost of IoRT solutions. These expenses usually limit the affordability of IoRT-based systems in developing countries, and also in scenarios where the operational cost is an issue to address. This paper presents an extension to the LoRaWAN protocol, named Node-Aware-LoRaWAN (NA-LoRaWAN), that reduces the traffic in the backhaul, thus decreasing the operational expenses of IoRT-based systems. In order to evaluate the performance of NA-LoRaWAN, it was compared to a regular LoRaWAN implementation. Depending on the network scenario, the proposed extension reduced the traffic through the backhaul in the range of 12–34%. This extension opens several opportunities to use IoRT solutions in application domains with a low operational budget, e.g., precision agriculture, environmental monitoring and natural hazards’ early detection. Full article

(This article belongs to the Special Issue Use Wireless Sensor Networks for Environmental Applications)

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20 pages, 7839 KiB

Open AccessArticle

Water IoT Monitoring System for Aquaponics Health and Fishery Applications

by Mohammad Alselek, Jose M. Alcaraz-Calero, Jaume Segura-Garcia and Qi Wang

Sensors 2022, 22(19), 7679; https://doi.org/10.3390/s22197679 - 10 Oct 2022

Cited by 4 | Viewed by 6551

Abstract

Aquaponic health is a very important in the food industry field, as currently there is a huge amount of fishing farms, and the demands are growing in the whole world. This work examines the process of developing an innovative aquaponics health monitoring system [...] Read more.

Aquaponic health is a very important in the food industry field, as currently there is a huge amount of fishing farms, and the demands are growing in the whole world. This work examines the process of developing an innovative aquaponics health monitoring system that incorporates high-tech back-end innovation sensors to examine fish and crop health and a data analytics framework with a low-tech front-end approach to feedback actions to farmers. The developed system improves the state-of-the-art in terms of aquaponics life cycle monitoring metrics and communication technologies, and the energy consumption has been reduced to make a sustainable system. Full article

(This article belongs to the Special Issue Use Wireless Sensor Networks for Environmental Applications)

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22 pages, 5233 KiB

Open AccessArticle

Long-Range Wireless System for U-Value Assessment Using a Low-Cost Heat Flux Sensor

by Marc Lazaro, Antonio Lazaro, Benito González, Ramon Villarino and David Girbau

Sensors 2022, 22(19), 7259; https://doi.org/10.3390/s22197259 - 25 Sep 2022

Cited by 2 | Viewed by 1838

Abstract

The present study exposes an economical and easy-to-use system to assess the heat transfer in building envelopes by determining the U-value. Nowadays these systems require long wires and a host to collect and process the data. In this work, a multi-point system for [...] Read more.

The present study exposes an economical and easy-to-use system to assess the heat transfer in building envelopes by determining the U-value. Nowadays these systems require long wires and a host to collect and process the data. In this work, a multi-point system for simultaneous heat flux measurement has been proposed. The aim is to reduce the long measurement time and the cost of thermal isolation evaluations in large buildings. The system proposed consists of a low-cost 3D-printed heat flux sensor integrated with a LoRa transceiver and two temperature sensors. The heat flux (HF) sensor was compared and calibrated with a commercial HF sensor from the Fluxteq brand. Full article

(This article belongs to the Special Issue Use Wireless Sensor Networks for Environmental Applications)

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17 pages, 3482 KiB

Open AccessEditor’s ChoiceArticle

Development of Wireless Sensor Network for Environment Monitoring and Its Implementation Using SSAIL Technology

by Shathya Duobiene, Karolis Ratautas, Romualdas Trusovas, Paulius Ragulis, Gediminas Šlekas, Rimantas Simniškis and Gediminas Račiukaitis

Sensors 2022, 22(14), 5343; https://doi.org/10.3390/s22145343 - 18 Jul 2022

Cited by 17 | Viewed by 4720

Abstract

The Internet of Things (IoT) technology and its applications are turning real-world things into smart objects, integrating everything under a common infrastructure to manage performance through a software application and offering upgrades with integrated web servers in a timely manner. Quality of life, [...] Read more.

The Internet of Things (IoT) technology and its applications are turning real-world things into smart objects, integrating everything under a common infrastructure to manage performance through a software application and offering upgrades with integrated web servers in a timely manner. Quality of life, the green economy, and pollution management in society require comprehensive environmental monitoring systems with easy-to-use features and maintenance. This research suggests implementing a wireless sensor network with embedded sensor nodes manufactured using the Selective Surface Activation Induced by Laser technology. Such technology allows the integration of electrical circuits with free-form plastic sensor housing. In this work, a low-cost asynchronous web server for monitoring temperature and humidity sensors connected to the ESP32 Wi-Fi module has been developed. Data from sensor nodes across the facility are collected and displayed in real-time charts on a web server. Multiple web clients on the same network can access the sensor data. The energy to the sensor nodes could be powered by harvesting energy from surrounding sources of electromagnetic radiation. This automated and self-powered system monitors environmental and climatic factors, helps with timely action, and benefits sensor design by allowing antenna and rf-circuit formation on various plastics, even on the body of the device itself. It also provides greater flexibility in hardware modification and rapid large-scale deployment. Full article

(This article belongs to the Special Issue Use Wireless Sensor Networks for Environmental Applications)

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26 pages, 54777 KiB

Open AccessArticle

Evaluating of IAQ-Index and TVOC Parameter-Based Sensors for Hazardous Gases Detection and Alarming Systems

by Mohammed Faeik Ruzaij Al-Okby, Sebastian Neubert, Thomas Roddelkopf, Heidi Fleischer and Kerstin Thurow

Sensors 2022, 22(4), 1473; https://doi.org/10.3390/s22041473 - 14 Feb 2022

Cited by 11 | Viewed by 4294

Abstract

The measurement of air quality parameters for indoor environments is of increasing importance to provide sufficient safety conditions for workers, especially in places including dangerous chemicals and materials such as laboratories, factories, and industrial locations. Indoor air quality index (IAQ-index) and total volatile [...] Read more.

The measurement of air quality parameters for indoor environments is of increasing importance to provide sufficient safety conditions for workers, especially in places including dangerous chemicals and materials such as laboratories, factories, and industrial locations. Indoor air quality index (IAQ-index) and total volatile organic Compounds (TVOC) are two important parameters to measure air impurities or air pollution. Both parameters are widely used in gases sensing applications. In this paper, the IAQ-index and TVOCs have been investigated to identify the best and most flexible solution for air quality threshold selection of hazardous/toxic gases detection and alarming systems. The TVOCs from the SGP30 gas sensor and the IAQ-index from the SGP40 gas sensor were tested with 12 different organic solvents. The two gas sensors are combined with an IoT-based microcontroller for data acquisition and data transfer to an IoT-cloud for further processing, storing, and monitoring purposes. Extensive tests of both sensors were carried out to determine the minimum detectable volume depending on the distance between the sensor node and the leakage source. The test scenarios included static tests in a classical chemical hood, as well as tests with a mobile robot in an automated sample preparation laboratory with different positions. Full article

(This article belongs to the Special Issue Use Wireless Sensor Networks for Environmental Applications)

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