Wireless Sensor Applications Research Articles

A Temperature Compensated CMOS Ring Oscillator for Wireless Sensing Applications

This paper presents a CMOS voltage controlled ring oscillator (VCO) with temperature compensation circuit suitable for low-cost and low-power MEMS gas sensor. This compensated ring oscillator is de...

Large-scale vibration energy harvesting

Nowadays, harvesting energy from vibration is one of the most promising technologies. However, the majority of current researches obtain 10 µW to 100 mW power, which has only limited applications in self-powered wireless sensors and low-power electronics. In fact, the vibrations in some situations can be very large, for example, the vibrations of tall buildings, long bridges, vehicle systems, railroads, ocean waves, and even human motions. With the global concern on energy and environmental issues, energy harvesting from large-scale vibrations is more attractive and becomes a research frontier. This article is to provide a timely and comprehensive review of the state-of-the-art on the large-scale vibration energy harvesting, ranging from 1 W to 100 kW or more. Subtopics include energy assessment from large vibrations, piezoelectric materials and electromagnetic transducers, motion transmission and magnification mechanisms, power electronics, and vibration control. The relevant applications discussed in this article include vibration energy harvesting from human motion, vehicles, transportations, and civil structures. The unique challenges and future research directions of large-scale vibration energy harvesting are also discussed.

A Continuous-Time ADC and Digital Signal Processing System for Smart Dust and Wireless Sensor Applications

A Continuous-Time ADC and Digital Signal Processing System for Smart Dust and Wireless Sensor Applications

0.18 ㎛ CMOS 공정을 이용한 저 전력 1 Ms/s 12-bit 2 단계 저항 열 방식 DAC

본 논문은 무선 센서분야를 위한 1MS/s rate의 저 전력 12-bit 2단계 저항 열 DAC를 제시하고 있다. 2단계 저항 열 구조를 채택함으로써 복잡함을 줄이고, 소비 전력을 최소화 하고 변환속도를 증가 시킬 수 있었다. 이 칩은 0.18 μm CMOS 공정에서 제작 되었으며, Die 면적은 0.76 μm x 0.56 μm 이다. 1.8V의 공급 전압으로부터 측정된 전력 소비는 1.8 mW 이다. 샘플링 주파수가 1MHz 이하에서 측정된 동적 동작범위(Spurious-Free Dynamic Range: SFDR)은 70dB 이다.

Wireless Surface Acoustic Wave Pressure and Temperature Sensor With Unique Identification Based on ${\rm LiNbO}_{3}$

Wireless sensor applications at elevated temperatures of around 200 $^{\circ}{\rm C}$ and above call for robust technologies such as surface acoustic wave (SAW) sensor designs. A combined pressure/temperature sensor with identification has been developed based on ${\rm LiNbO}_{3}$ substrate for condition monitoring applications in the baking industry. Due to the given temperature specification and to avoid adhesives, the design of the sensor was conceived as a classical beam arrangement supported by three balls. This paper presents an overview on the design process of the sensor beginning with the mechanical simulation of the sensor and the derivation of the SAW delay line to measure pressure, temperature, and to realize an ID functionality. The main result is a pressure sensitivity of 3.7 rad/bar with a temperature drift of 0.013 ${\rm rad}/^{\circ}{\rm C}$ . The sensitivity of the pressure sensor is also temperature dependent. This compound temperature drift can be compensated with the inherent temperature information of sensor.

Energy-Aware Design of Compressed Sensing Systems for Wireless Sensors Under Performance and Reliability Constraints

This paper describes the system design of a compressed sensing (CS) based source encoding system for data compression in wireless sensor applications. We examine the trade-off between the required transmission energy (compression performance) and desired recovered signal quality in the presence of practical non-idealities such as quantization noise, input signal noise and channel errors. The end-to-end system evaluation framework was designed to analyze CS performance under practical sensor settings. The evaluation shows that CS compression can enable over 10X in transmission energy savings while preserving the recovered signal quality to roughly 8 bits of precision. We further present low complexity error control schemes tailored to CS that further reduce the energy costs by 4X as well as diversity scheme to protect against burst errors. Results on a real electrocardiography (EKG) signal demonstrate 10X in energy reduction and corroborate the system analysis.

An Efficient Algorithm based on Fibonacci pattern Hound packets for Detection of Wormhole Attack in DSR for Mobile Ad Hoc Networks

networks are playing very important role in the present world. Mobile Ad hoc Networks (MANET) are the extension of the wireless networks. These networks are playing crucial role in the each and every field of the human life. They are used in those places where a simple wireless network cannot use. They play a significant role in real tile applications such as military applications, home applications wireless sensor applications etc. Due to their adaptive nature they are threatened by number of attacks such as Modification, Black Hole attack, Wormhole attack etc. Wormhole attack is one of the dangerous active attacks in the mobile Ad hoc Networks (MANET). In this paper a secure and efficient approach for the detection of the wormhole attack in the Mobile Ad Hoc Networks (MANET) is described. The algorithm is implemented in a very popular on demand routing protocol, called DSR (Dynamic Source Routing) protocol. In this approach the solution is provided by sending the Hound Packet in the order of Fibonacci series and also modifies the table entries in terms of storing them in sorted order, so that the processing of Route Discovery becomes faster.

Novel Miniature Airflow Energy Harvester for Wireless Sensing Applications in Buildings

This paper presents a novel miniature airflow energy harvester for wireless sensing applications. The energy harvester consists of a wing that is attached to a cantilever spring. The wing oscillates in response to a steady airflow. An electromagnetic transducer is used to extract electrical energy from the airflow-induced oscillations. Both vertical and horizontal orientations are studied. Experiments show that such a generator can operate at airflow speeds as low as 1.5 m·s-1, which compares well to turbines. When the airflow speed is over 2 m·s-1, the average output power exceeds 90 μW, which is sufficient for powering wireless sensor nodes in heat, ventilation, and air conditioning systems in buildings.

Time-Domain UWB RFID Tag Based on Reflection Amplifier

This letter describes an active ultrawideband (UWB) tag for radio frequency identification (RFID) and wireless sensor applications. The tag is composed by a UWB antenna connected to a one-port reflection amplifier. A UWB impulse radar is used as the reader. The reader sends a short pulse, and its echo is amplified and reflected back due to the return gain of the tag amplifier. The amplitude of the reflected pulse is modulated by controlling the amplifier bias. The basic theory of ultrawideband operation applied to the time-domain RFID system is described. Experimental results with a proof-of-concept tag using commercial components are presented.

Application-centric recovery algorithm for wireless sensor and actor networks

Sustaining actor-actor connectivity is extremely crucial in mission-critical applications of wireless sensor and actor networks where actors have to quickly plan optimal coordinated responses to detected events. This paper presents ACR, a novel hybrid application-centric connectivity restoration algorithm that factors in the application besides efficient resource utilisation while recovering from critical node failures. As a pre-failure planning measure to minimise recovery delay, ACR identifies the actors' primaries that are critical for network connectivity based on localised information and then designates for them backup nodes. The backup nodes are carefully picked to satisfy application concerns such as actor effectiveness. In order to minimise the impact of critical node failure on coverage and connectivity, ACR appoints high degree nodes with overlapped coverage. Upon failure detection, the pre-designated backup pursues controlled and coordinated movement to replace the failed node. We prove the convergence of ACR and analytically derive bounds on its performance. Simulation results further confirm the performance of ACR.

An Enhanced Security Scheme for Wireless Sensor Network Using Mobile Sink Server

Wireless sensor networks consisting of a large number of low power, low cost sensor node that communicate wirelessly. Such sensor networks can be used in wide range of applications such as military sensing and tracking, health monitoring etc, when the sensing field is too far from the station, transmitting data over long distance using multi-hop may weaken the security strength. To overcome this problem, mobile sinks (MS) are used. Mobile sinks plays a vital role in many wireless sensor applications for efficient data collection and localized sensor reprogramming. MS prolong the lifetime of the sensor network. Security became a critical issue when sensor network with MS are deployed in hostile environment. For providing more security against clone attack and Sybil attack, the proposed scheme implements mobile sink server to offer better security. In Sybil attack, the malicious device illegitimately taking on multiple identities whereas in, clone attack, adversaries may easily capture and compromise sensors and deploy unlimited number of clones of the compromised nodes. Based on the parameters such as bandwidth utilization, speed and time, the malicious act by the adversary are detected. And MS is assigned randomly once it is exposed to threat.

Covering Points of Interest with Mobile Sensors

The coverage of Points of Interest (PoI) is a classical requirement in mobile wireless sensor applications. Optimizing the sensors self-deployment over a PoI while maintaining the connectivity between the sensors and the base station is thus a fundamental issue. This paper addresses the problem of autonomous deployment of mobile sensors that need to cover a predefined PoI with a connectivity constraint. In our algorithm, each sensor moves toward a PoI but has also to maintain the connectivity with a subset of its neighboring sensors that are part of the Relative Neighborhood Graph (RNG). The Relative Neighborhood Graph reduction is chosen so that global connectivity can be provided locally. Our deployment scheme minimizes the number of sensors used for connectivity thus increasing the number of monitoring sensors. Analytical results, simulation results and practical implementation are provided to show the efficiency of our algorithm.

Pyroelectric Nanogenerators for Driving Wireless Sensors

We demonstrate a pyroelectric nanogenerator (PENG) based on a lead zirconate titanate (PZT) film, which has a pyroelectric coefficient of about -80 nC/cm(2)K. For a temperature change of 45 K at a rate of 0.2 K/s, the output open-circuit voltage and short-circuit current density of the PENG reached 22 V and 171 nA/cm(2), respectively, corresponding to a maximum power density of 0.215 mW/cm(3). A detailed theory was developed for understanding the high output voltage of PENG. A single electrical output pulse can directly drive a liquid crystal display (LCD) for longer than 60 s. A Li-ion battery was charged by the PENG at different working frequencies, which was used to drive a green light-emitting diode (LED). The demonstrated PENG shows potential applications in wireless sensors.

Effect of anisotropy on characteristics and behavior of shear horizontal SAWs in resonators using langasite

Orientations of langasite (LGS) with Euler angles (0°, μ, 90°) are potentially useful for applications in wireless SAW sensors because of wide variation of their temperature coefficient of frequency (TCF), between -50 and +50 ppm/°C, combined with high values of electromechanical coupling coefficient, especially if thick electrodes are utilized. The nature and characteristics of shear-horizontally polarized SAWs (SHSAWs) propagating in these orientations are investigated using a combination of numerical techniques: analysis of the BAW slowness surface and its effect on the SH-SAW structure; visualization of displacements that follow wave propagation in the grating; calculation of admittance of infinite periodic gratings; and analysis of SAW dispersion in the gratings, including possible interaction between SH-SAWs and parasitic Rayleigh SAWs. The characteristics of SH-SAWs propagating in symmetric cuts (velocities, localization depth, electromechanical coupling, etc.) are supplemented by analysis of propagation directions deviating from the YZ-plane toward the x-axis of LGS, for the temperature compensated cut with Euler angles (0°, 22°, 90°) and one more orientation for comparison. This extended analysis reveals that in actual devices, the anisotropy may be a reason for strong interaction between SH-SAWs and parasitic Rayleigh SAWs and cause degradation of the device's performance.

Application-Oriented Fault Detection and Recovery Algorithm for Wireless Sensor and Actor Networks

Recent years have witnessed a growing interest in applications of wireless sensor and actor networks (WSANs). In WSANs, maintaining interactor connectivity is of vital concern in order to reach application level. Failure of a critical actor may partition the inter-actor network into disjoint segments. This paper proposed an application-oriented fault detection and recovery algorithm (AFDR), a novel distributed algorithm to reestablish connectivity. AFDR identifies critical actors and designates backups for them. A backup actor detects the critical node failure and initiates a recovery process via moving to the optimal position. The purpose of AFDR is to satisfy application requirements, reduce recovery overhead, and limit the impact of critical node failure on coverage and connectivity to the utmost. The effectiveness of AFDR is validated through simulation experiments.

Formal Specification and Validation of a Hybrid Connectivity Restoration Algorithm for Wireless Sensor and Actor Networks

Maintaining inter-actor connectivity is extremely crucial in mission-critical applications of Wireless Sensor and Actor Networks (WSANs), as actors have to quickly plan optimal coordinated responses to detected events. Failure of a critical actor partitions the inter-actor network into disjoint segments besides leaving a coverage hole, and thus hinders the network operation. This paper presents a Partitioning detection and Connectivity Restoration (PCR) algorithm to tolerate critical actor failure. As part of pre-failure planning, PCR determines critical/non-critical actors based on localized information and designates each critical node with an appropriate backup (preferably non-critical). The pre-designated backup detects the failure of its primary actor and initiates a post-failure recovery process that may involve coordinated multi-actor relocation. To prove the correctness, we construct a formal specification of PCR using Z notation. We model WSAN topology as a dynamic graph and transform PCR to corresponding formal specification using Z notation. Formal specification is analyzed and validated using the Z Eves tool. Moreover, we simulate the specification to quantitatively analyze the efficiency of PCR. Simulation results confirm the effectiveness of PCR and the results shown that it outperforms contemporary schemes found in the literature.

A low power consumption CMOS differential-ring VCO for a wireless sensor

This paper describes a new three-stage voltage controlled ring oscillator (VCO) based on 0.35 μm standard CMOS technology. The VCO was designed for a transmitter operating in the 863–870 MHz European band for wireless sensor applications. The transmitter is designed for binary frequency-shift keying (BFSK) modulation, communicating a maximum data rate of 20 kb/s. In addition to the VCO, the transmitter combines a BFSK modulator, an up conversion mixer, a power amplifier and an 863–870 MHz band pass filter. The modulator uses the frequency hopping spread spectrum and it is intended for short range wireless applications, such as wireless sensor networks. The oscillation frequency of the VCO is controlled by a voltage VCTRL. Simulation results of the fully differential VCO with positive feedback show that the estimated power consumption, at desired oscillation frequency and under a supply voltage of 3.3 V, is only 7.48 mW. The proposed VCO exhibits a phase noise lower than −126 dBc/Hz at 10 MHz offset frequency.

TinyOS-based real-time wireless data acquisition framework for structural health monitoring and control

SUMMARY Wireless smart sensor networks have become an attractive alternative to traditional wired sensor systems to reduce implementation costs of structural health monitoring systems. The onboard sensing, computation, and communication capabilities of smart wireless sensors have been successfully leveraged in numerous monitoring applications. However, the current data acquisition schemes, which completely acquire data remotely prior to processing, limit the applications of wireless smart sensors (e.g., for real-time visualization of the structural response). Although real-time data acquisition strategies have been explored, challenges of implementing high-throughput real-time data acquisition over larger network sizes still remain because of operating system limitations, tight timing requirements, sharing of transmission bandwidth, and unreliable wireless radio communication. This paper presents the implementation of real-time wireless data acquisition on the Imote2 platform. The challenges presented by hardware and software limitations are addressed in the application design. The framework is then expanded for high-throughput applications that necessitate larger networks sizes with higher sampling rates. Two approaches are implemented and evaluated on the basis of network size, associated sampling rate, and data delivery reliability. Ultimately, the communication and processing protocol allows for near-real-time sensing of 108 channels across 27 nodes with minimal data loss. Copyright © 2012 John Wiley & Sons, Ltd.

A combined photovoltaic and Li ion battery device for continuous energy harvesting and storage

The design, fabrication, and initial analysis of a continuous energy harvesting and storage device for wireless sensor applications were undertaken. A Si nanowire-based photovoltaic (PV) device and Li ion battery were integrated onto a single Si substrate. The three terminal device consisted of separate positive terminals for each component and a shared negative electrode. The effect of Li+ incorporation into the planar PV electrode was evaluated. The current–voltage behavior of the PV device was tolerant to high Li+ concentrations. A titanium nitride layer between the battery and PV portions of the shared electrode was shown to be an effective diffusion barrier to Li+ incorporation.

Rethinking Java call stack design for tiny embedded devices

The ability of tiny embedded devices to run large feature-rich programs is typically constrained by the amount of memory installed on such devices. Furthermore, the useful operation of these devices in wireless sensor applications is limited by their battery life. This paper presents a call stack redesign targeted at an efficient use of RAM storage and CPU cycles by a Java program running on a wireless sensor mote. Without compromising the application programs, our call stack redesign saves 30% of RAM, on average, evaluated over a large number of benchmarks. On the same set of bench-marks, our design also avoids frequent RAM allocations and deallocations, resulting in average 80% fewer memory operations and 23% faster program execution. These may be critical improvements for tiny embedded devices that are equipped with small amount of RAM and limited battery life. However, our call stack redesign is equally effective for any complex multi-threaded object oriented program developed for desktop computers. We describe the redesign, measure its performance and report the resulting savings in RAM and execution time for a wide variety of programs.