Sensing Node Research Articles

TEG-Self-Powered System for Wireless Sensing Node Operating in Aqua-Greenhouse

TEG-Self-Powered System for Wireless Sensing Node Operating in Aqua-Greenhouse

Energy Autonomous Wireless Sensing Node Working at 5 Lux from a 4 cm2 Solar Cell

Harvesting energy for IoT nodes in places that are permanently poorly lit is important, as many such places exist in buildings and other locations. The need for energy-autonomous devices working in such environments has so far received little attention. This work reports the design and test results of an energy-autonomous sensor node powered solely by solar cells. The system can cold-start and run in low light conditions (in this case 20 lux and below, using white LEDs as light sources). Four solar cells of 1 cm2 each are used, yielding a total active surface of 4 cm2. The system includes a capacitive sensor that acts as a touch detector, a crystal-accurate real-time clock (RTC), and a Cortex-M3-compatible microcontroller integrating a Bluetooth Low Energy radio (BLE) and the necessary stack for communication. A capacitor of 100 μF is used as energy storage. A low-power comparator monitors the level of the energy storage and powers up the system. The combination of the RTC and touch sensor enables the MCU load to be powered up periodically or using an asynchronous user touch activity. First tests have shown that the system can perform the basic work of cold-starting, sensing, and transmitting frames at +0 dBm, at illuminances as low as 5 lux. Harvesting starts earlier, meaning that the potential for full function below 5 lux is present. The system has also been tested with other light sources. The comparator is a test chip developed for energy harvesting. Other elements are off-the-shelf components. The use of commercially available devices, the reduced number of parts, and the absence of complex storage elements enable a small node to be built in the future, for use in constantly or intermittently poorly lit places.

Synchronization of Chaotic Systems and Its Application in Security Terminal Sensing Node of Internet of Things.

Recently, with the rapid development of data and information, it has become necessary to establish secure communications and appropriate security services to ensure a secure information exchange process. Therefore, to protect the privacy and confidentiality of private data, in this research, we use the Lorenz chaotic system to generate chaotic signals and apply them to the encryption of the communication of the Internet of Things (IoT) terminal sensor nodes. In addition, we design a simple proportional-integral-derivative (PID) controller and a quasi-sliding mode controller (QSMC) to synchronize the master-slave chaotic systems for decrypting the signals. Then, we encrypt the environmental signals measured from the IoT node at the transmitting side (master) and send them to the receiving side (slave). After the receiving side receives the encrypted signals, it decrypts them with the PID controller. Thus, the security of IoT information can be assured and realized.

An efficient secure data transmission and node authentication scheme for wireless sensing networks

With the development of big data era, wireless sensor networks (WSNs) are widely used. However, the wireless sensing network has the disadvantages that it is difficult to monitor after deployment and the node energy after deployment cannot be supplemented. Therefore, this paper proposes an efficient and high-performance data acquisition scheme, and realizes the authentication of effective nodes and the confidentiality of data transmission. Firstly, the sensing node uses compressed sensing sampling network (CSSN) to complete high-performance data collection, and applies deep learning to wireless sensing network data collection. Secondly, the lightweight hash algorithm is applied to process the ID and timestamp time of each node to realize the identification and authentication of the sink node, and avoid the replay attack. Finally, the Paillier additive homomorphic encryption is used to encrypt the signed data to realize the confidential transmission of data. At the same time, this scheme evaluates the reputation of each sense node and deletes the damaged nodes invaded by attackers from the network. Taking image information acquisition as an example, a large number of experiments have proved the feasibility and applicability of this scheme.

A Multifunctional Battery-Free Bluetooth Low Energy Wireless Sensor Node Remotely Powered by Electromagnetic Wireless Power Transfer in Far-Field.

This paper presents a multifunctional battery-free wireless sensing node (SN) designed to monitor physical parameters (e.g., temperature, humidity and resistivity) of reinforced concrete. The SN, which is intended to be embedded into a concrete cavity, is autonomous and can be wirelessly powered thanks to the wireless power transmission technique. Once enough energy is stored in a capacitor, the active components (sensor and transceiver) are supplied with the harvested power. The data from the sensor are then wirelessly transmitted via the Bluetooth Low Energy (BLE) technology in broadcasting mode to a device configured as an observer. The feature of energy harvesting (EH) is achieved thanks to an RF-to-DC converter (a rectifier) optimized for a low power input level. It is based on a voltage doubler topology with SMS7630-005LF Schottky diode optimized at −15 dBm input power and a load of 10 kΩ. The harvested DC power is then managed and boosted by a power management unit (PMU). The proposed system has the advantage of presenting two different power management units (PMUs) and two rectifiers working in different European Industrial, Scientific and Medical (ISM) frequency bands (868 MHz and 2.45 GHz) depending on the available power density. The PMU interfaces a storage capacitor to store the harvested power and then power the active components of the sensing node. The low power digital sensor HD2080 is selected to provide accurate humidity and temperature measurements. Resistivity measurement (not reported in this paper) can also be achieved through a current injection on the concrete probes. For wireless communications, the QN9080 system-on-chip (SoC) was chosen as a BLE transceiver thanks to its attractive features: a small package size and extremely low power consumption. For low power consumption, the SN is configured in broadcasting mode. The measured power consumption of the SN in a deep-sleep mode is 946 µJ for four advertising events (spaced at 250 ms maximum) after the functioning of sensors. It also includes voltage offset cancelling functionality for resistivity measurement. Far-field measurement operated in an anechoic chamber with the most efficient PMU (AEM30940) gives a first charging time of 48 s (with an empty capacitor) and recharge duration of 27 s for a complete measurement and data transmission cycle.

Motion Model of Floating Weather Sensing Node for Typhoon Detection

To improve the accuracy of typhoon prediction, it is necessary to detect the internal structure of a typhoon. The motion model of a floating weather sensing node becomes the key to affect the channel frequency expansion performance and communication quality. This study proposes a floating weather sensing node motion modeling method based on the chaotic mapping. After the chaotic attractor is obtained by simulation, the position trajectory of the floating weather sensing node is obtained by space and coordinate conversion, and the three-dimensional velocity of each point on the position trajectory is obtained by multidimensional linear interpolation. On this basis, the established motion model is used to study the Doppler frequency shift, which is based on the software and physical platform. The software simulates the relative motion of the transceiver and calculates the Doppler frequency shift. The physical platform can add the Doppler frequency shift to the actual transmitted signal. The results show that this method can effectively reflect the influence of the floating weather sensing node motion on signal transmission. It is helpful to research the characteristics of the communication link and the design of a signal transceiver for typhoon detection to further improve the communication quality and to obtain more accurate interior structure characteristic data of a typhoon.

A Virtual Projection-Based Incentive Routing Protocol for Mobile PFNs in Wireless Sensor Networks

The current Wireless Sensor Network (WSN) lacks the desired power owning to the non-availability of the power source. The challenge posed in the current scenario is conserving power for effective data transfer, which is seldom achieved. Added to the owes is the evolving technological innovations where the physical size of the Packet Forwarding Nodes (PFNs) is also reduced along with its power source, thereby reducing the power available to the system and making it inefficient. The existing methodology employed in monitoring the parameters used in Epidemic Algorithm (EA) and Incentive Compatible Routing Protocol (ICRP) protocols which are power guzzlers, the power available for data transfer is greatly reduced making the entire system inefficient. This paper attempts to mitigate the challenges posed by the EA & ICRP, the proposed protocol, “Incentive Routing Protocol with Virtual Projection (IRPVP)”, employs a Relay Sensing Node (RSN) which is designed to be distributed in a square cross-sectional area where each node acts as a unique Sensing Point (SP) monitoring each of the essential parameters like energy consumption, vibrant & non-vibrant SPN count, residual energy and routing overhead while still retaining power for data transfer since the RSN is connected to a dedicated power source. In IRPVP protocol, each packet of a node is subdivided into fragments that are designed to have fixed or variable lengths depending upon the application. Each of these packets is sent over multiple Packet Forwarding Nodes (PFNs) towards the data center. The selection of PFNs in the path is based on their trust levels like meeting probability, computation of residual energy, data weight, and security value. Special PFNs are placed in the network and are entrusted to deliver the packets to the data center without data loss during transmission. The result of the IRPVP protocol Vis-à-Vis the EA & ICRP protocol, backed by the simulation results proves that the IRPVP protocol is better in data handling and is more efficient.

Compact Antenna in 3D Configuration for Rectenna Wireless Power Transmission Applications.

This work presents methods for miniaturizing and characterizing a modified dipole antenna dedicated to the implementation of wireless power transmission systems. The antenna size should respect the planar dimensions of 60 mm × 30 mm to be integrated with small IoT devices such as a Bluetooth Lower Energy Sensing Node. The provided design is based on a folded short-circuited dipole antenna, also named a T-match antenna. Faced with the difficulty of reducing the physical dimensions of the antenna, we propose a 3D configuration by adding vertical metallic arms on the edges of the antenna. The adopted 3D design has an overall size of 56 mm × 32 mm × 10 mm at 868 MHz. Three antenna-feeding techniques were evaluated to characterize this antenna. They consist of soldering a U.FL connector on the input port; vertically connecting a tapered balun to the antenna; and integrating a microstrip transition to the layer of the antenna. The experimental results of the selected feeding techniques show good agreements and the antenna has a maximum gain of +1.54 dBi in the elevation plane (E-plane). In addition, a final modification was operated to the designed antenna to have a more compact structure with a size of 40 mm × 30 mm × 10 mm at 868 MHz. Such modification reduces the radiation surface of the antenna and so the antenna gain and bandwidth. This antenna can achieve a maximum gain of +1.1 dBi in the E-plane. The two antennas proposed in this paper were then associated with a rectifier to perform energy harvesting for powering Bluetooth Low Energy wireless sensors. The measured RF-DC (radiofrequency to direct current) conversion efficiency is 73.88% (first design) and 60.21% (second design) with an illuminating power density of 3.1 µW/cm2 at 868 MHz with a 10 kΩ load resistor.

Scalable spectrum database construction mechanisms for efficient wideband spectrum access management

We propose a novel framework for enabling scalable database-driven dynamic spectrum access and sharing of heterogeneous wideband spectrum. The proposed framework consists of two complementary approaches that exploit the merits of compressive sensing theory, low-rank matrix theory, and user cooperation to build an accurate heterogeneous wideband spectrum map by overcoming the time-variability of the number of occupied bands, the need for a high number of measurements per sensing node (SN), the inherent wireless channels’ impairments, and the high reporting network overhead. First, exploiting the fact that close-by SNs have a highly correlated spectrum observation, we leverage distributed compressive sensing to enable cooperative heterogeneous wideband spectrum sensing only from a small number of measurements per each SN. Second, to reduce the network overhead due to the high width of the spectrum of interest, we propose a two-step approach that performs spectrum occupancy recovery using the local low-rank property of occupancy sub-matrices. Then, we combine the completed sub-matrices entries to produce the whole spectrum occupancy matrix. Through simulations, we show that the proposed framework efficiently achieves high detection in the sensing step and minimizes the spectrum occupancy matrix recovery error while reducing the overall network overhead.

Sensing node selection and mobile sink displacement in the environments with multiple targets

In target tracking scenarios, a suitable sensor selection method in combination with designing mobile sinks (MSes) movement path is a promising solution to maximise the lifetime of the wireless sensor network (WSN). The lifetime optimization problem is non-deterministic polynomial-time hardness (NP-hard) and its optimal solution requires an exhaustive search with the exponential complexity. To tackle this issue, the original problem is separated into two more tractable sub-problems: first, the MSes' assignment and their positions' calculations, second, the SN assignment problem. The SNs assignment problem is an integer programing, which is relaxed to the more tractable form. Moreover, its solution results in a priority function which is combined with a numerical search algorithm to select the SNs. In the proposed framework, based on the estimated path of each target, a MS is assigned to the target. Besides, the MSes optimum position in the next rounds are calculated. Afterwards, for each target at each round, sensing nodes (SNs) are selected based on the targets' position and the MSes' position. Simulation results show that proposed solution increases the network's lifetime considerably in comparison with the benchmark algorithms while its complexity is much lower than that of the optimal exhaustive search algorithm.

Water current measurements using oceanographic bottom lander LoTUS

LoTUS is a bottom landing, Long Term Underwater Sensing node made for the observation of ocean water temperatures. LoTUS is moored to the seafloor and measures temperature according to a specified time schedule until, at the end of the mission, it surfaces to transmit the collected data to on-shore recipients using an Iridium link. The paper presents an extension of the sensing capability which includes water current velocity (speed and direction) using a robust, reliable and inexpensive Eulerian method. The method is based on the “tilting stick” principle where a combination of inertial and magnetic measurement data are used. The paper discusses the principal technique, modeling of the system, practical considerations, optimization of the setup for specific flow conditions, and the verification of experimental data.

Reconfigurable Multiple Sensing node for the Automation of Agricultural Field

In a real time system, monitoring and control of various parameters of the field is vital .In order to achieve high yields and quality , exact parameters of soils and its necessary inputs to soil need to be put in action. Pest and diseases are also important factors in decline of yield and quality. Considering the various applications of this area, the present paper explains the wireless multi-sensing node for remote monitoring and control system for agricultural applications. This is design with a number of good performance front-end devices and circuits suitable for various types of sensors. Any Sensor device elements can be directly connected without the need of extra circuits. The number of input sensors can be reconfigured with time to time as system demand. The paper describes development and the interface of high performance and low-cost typical features elements. The developed system displayed all the measures field parameters and corresponding set point values on the LCD interface and also are stored in external interface memory for future reference. The developed node can be connected to a personal computing system for decision support using wired RS-232 interface or wireless connectivity using the RF modem from Xbee.

Bhattacharyya distance criterion based multibit quantizer design for cooperative spectrum sensing in cognitive radio networks

Cooperative spectrum sensing (CSS) is crucial for dynamic spectrum access in cognitive radio networks. This paper considers a CSS scheme by using a multilevel quantizer in each sensing node (SN) to quantize the local energy detector’s observation. A log-likelihood ratio test detector by using quantized data received from each SN is proposed to determine the presence or absence of the primary user signal. The Bhattacharyya distance (BD) of the cooperative sensing system is derived. Then, a quantizer design scheme by maximizing the BD that as the criterion function in an optimization problem with respect to the quantization thresholds is proposed. As nonlinear and high-dimensional of the objective function, a particle swarm optimization algorithm is employed to solve operating parameters for the quantizer. Furthermore, we derive the upper bound performance on cooperative energy detection (CED) in CSS. To validate the effectiveness of the proposed approach, The quantizer is compared with other schemes in terms of detection performance. Simulation results show that 2- or 3-bit quantization of the proposed approach achieves comparable performance to upper bound of CED without quantization.

Wireless sensor network in landslide monitoring system with remote data management

This paper describes a system that uses a wireless sensor network (WSN) to monitor landslide disasters in remote areas. The system consists of 3 subsystems called the Local Sensing Node Network System (LSNNS), the Cloud System (CS), and the Host System (HS). To monitor the field status and condition of the nodes remotely, we set up an appropriate management scheme in which the HS collects various data types in categories: node status, node data, LSNNS status, and LSNNS data. Equivalent lists are available to manage the HS and CS. Each data type contributes to 1 or 2 key analyses in determining a temporary situation. Experiments are conducted to investigate some featured data for landslide monitoring application, including node posture, dynamic change of topology, landslide occurrence recognition, and node location change. Where WSN is a candidate for monitoring natural disasters, this remote management scheme provides the surveillance process with extra information and helps the operator to comprehend the situation and maneuver with less effort.

Design and validation of a wearable "DRL-less" EEG using a novel fully-reconfigurable architecture.

The conventional EEG system consists of a driven-right-leg (DRL) circuit, which prohibits modularization of the system. We propose a Lego-like connectable fully reconfigurable architecture of wearable EEG that can be easily customized and deployed at naturalistic settings for collecting neurological data. We have designed a novel Analog Front End (AFE) that eliminates the need for DRL while maintaining a comparable signal quality of EEG. We have prototyped this AFE for a single channel EEG, referred to as Smart Sensing Node (SSN), that senses brain signals and sends it to a Command Control Node (CCN) via an I2C bus. The AFE of each SSN (referential-montage) consists of an off-the-shelf instrumentation amplifier (gain=26), an active notch filter fc = 60Hz), 2nd-order active Butterworth low-pass filter followed by a passive low pass filter (fc = 47.5 Hz, gain = 1.61) and a passive high pass filter fc = 0.16 Hz, gain = 0.83). The filtered signals are digitized using a low-power microcontroller (MSP430F5528) with a 12-bit ADC at 512 sps, and transmitted to the CCN every 1 s at a bus rate of 100 kbps. The CCN can further transmit this data wirelessly using Bluetooth to the paired computer at a baud rate of 115.2 kbps. We have compared temporal and frequency-domain EEG signals of our system with a research-grade EEG. Results show that the proposed reconfigurable EEG captures comparable signals, and is thus promising for practical routine neurological monitoring in non-clinical settings where a flexible number of EEG channels are needed.

A self-calibrated Wireless Sensing System for monitoring the ambient industrial environment. From lab to real-time application

The sensing performance of a self-calibrated Wireless Sensing System (WSS) was evaluated under laboratory and real environment conditions. The Wireless Sensing Node consists of a sensor array based on chemocapacitors, which is integrated with appropriate low power consumption read-out electronics and is connected with appropriate wireless module. The sensing system was evaluated and calibrated under laboratory conditions with two different VOCs transfer methods: dynamic and static. The sensing unit calibration deals with changes of VOCs and/or humidity concentration and temperature variations, simulating the real industrial environment. Finally the WSS was placed in the workspace of a printed flexing packaging industrial installation and comparison with the already installed commercial detectors was performed. A very good agreement between the results of the two measurement systems is demonstrated. Additionally these results showed that the WSS is characterized by fast response with high repeatability and long-term stability. Concluding, this system is suitable for the targeted application.

Implementation of Multiple Host Nodes in Wireless Sensing Node Network System for Landslide Monitoring

This paper proposes multiple host nodes in Wireless Sensing Node Network System (WSNNS) for landslide monitoring. As landslide disasters damage monitoring system easily, one major demand in landslide monitoring is the flexibility and robustness of the system to evaluate the current situation in the monitored area. For various reasons WSNNS can provide an important contribution to reach that aim. In this system, acceleration sensors and GPS are deployed in sensing nodes. Location information by GPS, enable the system to estimate network topology and enable the system to perceive the location in emergency by monitoring the node mode. Acceleration sensors deployment, capacitate this system to detect slow mass movement that can lead to landslide occurrence. Once deployed, sensing nodes self-organize into an autonomous wireless ad hoc network. The measurement parameter data from sensing nodes is transmitted to Host System via host node and "Cloud" System. The implementation of multiple host nodes in Local Sensing Node Network System (LSNNS), improve risk- management of the WSNNS for real-time monitoring of landslide disaster.

Virtual Clustered MAC Layer Protocol Design of a Wireless Sensor Network: ES-MAC

Sensor-MAC (S-MAC), one kind of use common type activities / sleep cycle wireless sensor network MAC layer protocol, we propose a strengthening type Enhanced S-MAC, called ES-MAC, and part of its application in wireless sensor networks than the outer layer of low traffic. ES-MAC is divided into three stages: the first stage is to create a virtual cluster region and preset transmission path; third stage of data transfer; second stage of data collection and sorting. Sensing node virtual cluster in the region, competitive manner using micro slot (Mini-Slot) determine the order of data transmission. In the data transfer phase has been established using the sequential transfer of data, the sense node in order to reduce the unnecessary and excessive collision monitoring, sleep time, and the growth of nodes. Simulation results show that, ES-MAC under different flow and different cycles, compared with S-MAC has lower average packet delay time.

Experimental Verification of a Passive Sensing Node for Monitoring RF Connector-Coaxial Cable System Performance

The concept of a network of passive sensing node (PSN) devices for monitoring the integrity of radio frequency (RF) coaxial transmission lines and associated RF connectors in the UHF range of frequencies was introduced in a previous paper. This paper examines the performance characteristics of the subsystems of an individual PSN device. It provides experimental verification of S-parameters of the transmission line coupler model, which was described in the previous paper. Experimental verification is also provided for power monitoring, power harvesting, and backscatter telemetry subsystems. The PSN reports 8-bit precision data from each of its sensory inputs including connector tightness, relative humidity, temperature, propagating RF power, harvested voltage, and the system voltage reference. The communication protocol for this data exchange is also discussed. Based on the results of these experiments, it is shown that a PSN-based network for monitoring transmission systems should be feasible.

The Development of a Monitoring System Using a Wireless and Powerless Sensing Node Deployed Inside a Spindle

Installation of a Wireless and Powerless Sensing Node (WPSN) inside a spindle enables the direct transmission of monitoring signals through a metal case of a certain thickness instead of the traditional method of using connecting cables. Thus, the node can be conveniently installed inside motors to measure various operational parameters. This study extends this earlier finding by applying this advantage to the monitoring of spindle systems. After over 2 years of system observation and optimization, the system has been verified to be superior to traditional methods. The innovation of fault diagnosis in this study includes the unmatched assembly dimensions of the spindle system, the unbalanced system, and bearing damage. The results of the experiment demonstrate that the WPSN provides a desirable signal-to-noise ratio (SNR) in all three of the simulated faults, with the difference of SNR reaching a maximum of 8.6 dB. Following multiple repetitions of the three experiment types, 80% of the faults were diagnosed when the spindle revolved at 4,000 rpm, significantly higher than the 30% fault recognition rate of traditional methods. The experimental results of monitoring of the spindle production line indicated that monitoring using the WPSN encounters less interference from noise compared to that of traditional methods. Therefore, this study has successfully developed a prototype concept into a well-developed monitoring system, and the monitoring can be implemented in a spindle production line or real-time monitoring of machine tools.