Wireless Passive Sensor Networks Research Articles

Cooperative Localization in Hybrid Active and Passive Wireless Sensor Networks With Unknown Tx Power

Hybrid active and passive wireless sensor networks (HWSNs) gain advantages in extending the network lifetime and reducing the overall cost. Because the passive sensors without battery harvest the energy from distributed active sensor signal beam, and only a few active sensors can maintain a large-scale network. Thus, how to track the passive sensor’s location is essential for network management. Since the active sensors are sparsely deployed, cooperative localization which employs passive sensors to locate themselves together is a promising solution. In this paper, we analyze the energy beam generated by the active sensors on the cooperative localization accuracy of the passive sensors. We consider the spatial-temporal cooperative localization based on the received signal strength (RSS) model with unknown Tx power information of each sensor due to the limited processing capabilities, circuit complexity and energy constraints. We formulate the Fisher information matrix (FIM) and the corresponding Cramér-Rao lower bound (CRLB) for the static full connected network and dynamic spatial-temporal recursive network. Accordingly, energy beamforming schemes are proposed to optimize localization accuracy and energy efficiency problems. For the optimal localization problem, we derive the closed-form solution of the optimal energy beamforming wave. For the optimal energy efficiency problem, we propose a semi-definite programming (SDP) solution to achieve optimal energy consumption with a self-calibration method, which can address the over-relax problem. Extensive simulation results indicate that our proposed beamforming schemes have high localization accuracy and lower power consumption compared with the existing power allocation-based schemes.

A neuro-fuzzy approach for multipoint data prediction in passive clustered wireless sensor networks

In Passive Clustered Wireless Sensor Networks (WSNs), energy is lost in a sensor node during the data transmission. In order to avoid the energy loss due to data transmission, a data prediction technique is implemented. In this paper, we present a new multi-point data prediction technique, in which the prediction algorithm is initially implemented at both member nodes and cluster heads. The algorithm is updated to cluster head by member nodes by tracking temporal correlation of data. Neuro-Fuzzy model is used as a predictor in both member nodes and cluster heads. The simulation is performed using MATLAB and the overall energy in nodes seems to increase. The mean square error (MSE) value is reduced to greater extend.

CRLB Analysis for Passive Sensor Network Localization Using Intelligent Reconfigurable Surface and Phase Modulation

Passive wireless sensor network (PWSN) requires high positioning for network management. The harvested energy of the passive sensor is modulated as the ranging data and the position is derived accordingly. Thus, the wireless power transfer (WPT) is a dominant factor for such localization. With the help of intelligent reconfigurable surface (IRS), the WPT efficiency can be significantly improved. In this paper, we propose the Fisher information matrix (FIM) and the Cramér–Rao lower bound (CRLB) analyzing model of the PWSN localization. We prove the impacts of phase modulation of IRS on the localization performance. Based on our analysis, we develop an approximation algorithm and a genetic algorithm to control the IRS phases. Then, the localization accuracy of PWSN can be further improved. The simulation results demonstrate that the phase modulation based on GA can achieve high accurate localization for PWSN using IRS.

Passive Wireless Sensor Network-Based In-Transit Health Status Monitoring for Railway Transportation

In this paper, passive wireless sensor network technology is used to conduct in-depth research and analysis on the monitoring of the in-transit health status of railway transportation. Safety detection sensors, train communication networks, and other onboard devices organically constitute a train sensor network with comprehensive state sensing, information aggregation, and business collaboration. First, this paper analyzes the three-layer architecture of the sensing layer, network layer, and application layer of the train operation status safety detection sensor network. Based on analyzing the feasibility of Ethernet application in an onboard communication network, ring, multiring, and ladder-type sensor network structure schemes are designed. Next, the real-time performance and reliability of various sensor network structures are analyzed. First, the characteristics of bandwidth demand, priority, and importance of information transmission of each monitoring object are analyzed; then, the system utility function is established according to the bandwidth usage efficiency and communication demand of information transmission of each monitoring object; finally, the bandwidth allocation optimization model is solved by using a particle swarm optimization algorithm, and the remaining bandwidth resources are dynamically rationed on demand while ensuring the complete transmission of basic information of each monitoring object. Rail transit technology has profoundly affected and changed the travel and lifestyle of residents in the new era and will provide strong infrastructure support for the smooth advancement of new urbanization construction and development strategies. The remaining bandwidth resources are dynamically allocated on the premise of ensuring the complete transmission of basic information of each monitoring object. In summary, this paper presents a complete study on the optimal allocation of resources for wireless sensor networks dedicated to rail transit condition monitoring, starting from the perspectives of routing protocol optimization, data fusion rate optimization, and bandwidth dynamic allocation optimization to achieve the efficient use of limited resources. The achieved research results enrich the research content in the field of wireless monitoring of rail transit system conditions at home and abroad in a certain sense and will also provide theoretical and empirical support for practical practitioners, managers, and scholars of service condition monitoring of rail transit systems.

Asymptotic Normality of and Normal Approximation to Interference Power in Wireless Passive Sensor Networks

A wireless passive sensor network is distinguished from ordinary wireless sensor networks by radio frequency (RF) sources that radiate RF waves and supply energy to sensor nodes. Against theoretical expectations, such a network suffers from a scarcity of energy, which compels to employ a contending-type medium access control (MAC) scheme. Consequently, a collision may take place among the packets sent by some sensor nodes. Also, the interference power brought by the colliding packets may hinder a sink node from identifying any packet. Apparently, the interference power highly influences the performance of a wireless passive sensor network. Thus, it is essential to appropriately describe the interference power to evaluate the performance. In this paper, we characterize the interference power, occurring in a wireless passive sensor network, as a sum of random variables governed by log-normal distributions, which are mutually independent but are not necessarily identical. Then, we prove the asymptotic normality of the interference power and, in pursuit of tractability rather than accuracy, we propose a normal approximation to the interference power brought by a finite number of sensor nodes. To investigate the accuracy of the proposed normal approximation, we take the Kolmogorov-Smirnov distance and present an exact expression of the Berry-Esséen bound associated with the interference power. Also, to explore the acceptability of the normal approximation, we employ three well-known statistical tests for normality. Comparative studies of Berry-Esséen bounds reveal that the normal approximation to the interference power is moderately accurate. Furthermore, hypothesis testing for normality shows that the normal approximation is acceptable even in the case that the interference power is incurred by a relatively small number of packets (or, equivalently, sensor nodes) in a wireless passive sensor network.

Timeliness-aware Anti-discrimination MAC Scheme for Wireless Passive Sensor Networks

In a wireless passive sensor network, radio frequency (RF) sources wirelessly supply energy to sensor nodes. Against theoretical expectations of an abundance of energy, a wireless passive sensor network suffers from a scarcity of energy in practice. Such a scarcity compels the network to adopt a contending-type medium access control (MAC) scheme, which inevitably brings about a packet collision, and hence a capture phenomenon. The problem is that the packet collision may incur an intolerable delay in packet delivery, and furthermore, the capture phenomenon can cause discrimination in packet delivery against sensor nodes that are far from the sink node. In this paper, we thus confine our attention to a class of contending-type MAC schemes, rooted in framed and slotted ALOHA, which guarantee a degree of timeliness in packet delivery. In the timeliness-aware class, we then seek an anti-discrimination MAC scheme that prevents discrimination against distant sensor nodes by providing every sensor node with an equal opportunity to succeed in packet delivery, i.e., in the substantive sense of equality. In case studies, we construct an antidiscrimination MAC scheme in an explicit form. Also, we develop an exact expression of nodal throughput that can be attained by an anti-discrimination MAC scheme. Using the throughput formula, we then find an optimal anti-discrimination MAC scheme that attains maximum total throughput among all the anti-discrimination MAC schemes. Numerical examples corroborate that an optimal anti-discrimination MAC scheme not only always achieves stronger nodal evenness in throughput but also occasionally attains higher total throughput than a conventional MAC scheme.

An energy efficient IS-MAC based on distributed coordination function (DCF) for wireless passive sensor networks

This work presented the depth analysis on various (MAC) layer protocols and designed algorithm. All these methods have been implemented and modified for the wireless networks. Some existing MAC algorithms are introduced with their problem and evaluation. Lastly, evaluation of various form of WSN behalf of the MAC present algorithms (such as S-MAC, IEEE802.11) to our proposed work. A new MAC algorithm is proposed on the concept of S-MAC issues which have contentions window (CWs) according to carrier - sense his secure in S-MACI & IS-MACI algorithm and capable to modify CW based on the system traffic, energy spent reduced in IS-MAC (Improved Sensor MAC). Same MAC algorithm is modified with DCF-MAC protocol to improve successful data transmission and energy consumption in the network. All the work carried on the NS2 network simulator.

A Selective, Tracking, and Power Adaptive Far-Field Wireless Power Transfer System

This paper proposes a selective, tracking, and power adaptive far-field wireless power transfer (WPT) system that may be integrated into passive wireless sensor networks (PWSNs). Both transmitter and receiving nodes are developed with features that allow them to cooperate. The system operates based on a backscattered pilot signal, which is used to control and focus the radiated energy. The transmitter may change between several states by turning on or off sets of antenna elements. Each of these states will transmit and consume a specific amount of power, and they will be selected based on the node’s received signal strength (RSS). The receiving nodes are low complexity and battery-less devices, which use a small portion of the rectified energy to create an RSS-dependent modulation frequency, used to drive a backscatter modulator. Based on the nonlinear response of the rectifying devices, additional hardware was integrated into the nodes to activate/wake up them from specific wireless power signals. A complete system operating at 5.8 GHz for WPT and 3.6 GHz for the pilot signal is reported. It will be shown that effective far-field WPT links can be created with reasonable simplicity.

Integrated cmos rectifier for rf-powered wireless sensor network nodes

This article presents a review of the CMOS rectifier for radio frequency energy harvesting application. The on-chip rectifier converts the ambient low-power radio frequency signal coming to antenna to useable DC voltage that recharges energy to wireless sensor network (WSN) nodes and radiofrequency identification (RFID) tags, therefore the rectifier is the most important part of the radio frequency energy harvesting system. The impedance matching network maximizes power transfer from antenna to rectifier. The design and comparison between the simulation results of one- and multi-stage differential drive cross connected rectifier (DDCCR) at the operating frequencies of 2.44GHz, and 28GHz show the output voltage of the multi-stage rectifier doubles at each added stage and power conversion efficiency (PCE) of rectifier at 2.44GHz was higher than 28GHz. The (DDCCR) rectifier is the most efficient rectifier topology to date and is used widely for passive WSN nodes and RFID tags.

A Passive Wireless Sensor Network for Temperature Mapping Inside a Shielded Coaxial Enclosure

This contribution addresses the electromagnetic feasibility of the wireless temperature monitoring inside a coaxial cavity resembling a portion of a high-power high-frequency cyclotron auto-resonance maser for plasma heating in the new generation of DEMO TOKAMAK machines. The scenario is investigated as a potential communication channel for a ultrahigh-frequency radiofrequency identification (RFID) sensor network where cavity probes are used to both excite the coaxial cavity and to collect the temperature data scattered back by sensor antennas. By using a theoretical near-field analysis of a simplified model of the cavity and of the reader/sensor devices it is demonstrated that a two-probes architecture is suitable to interact with more than $N =$ 16 equally spaced RFID temperature sensors (having power sensitivity of −8.3 dB mW) over the surface of a 0.5 m tube by using less than 20 dB mW power emitted by the reader. The theoretical results are corroborated by experimental data with a mock-up of the cavity and realistic prototypes of miniaturized RFID radio-sensors and excitation probes.

Efficient data association to targets for tracking in passive wireless sensor networks

We have developed an algorithm for efficient data association to targets, the two-way cluster association (TWCA) algorithm, for tracking multiple targets in passive wireless sensor networks (PWSNs). PWSN applications require that the sensors have low computational and communication loads as the sensors are battery powered. We choose PWSNs as each sensor node triggers target detection and tracking only in the presence of the signals. However, the PWSNs make the association difficult because the detected signal by a passive sensor may come from targets nearby and/or far from the sensor depending on the target signal powers. The difficulty for the data association is further amplified when multiple targets undergo complex maneuvers including merging and split. The TWCA algorithm solves the association problem with very simple operations by using the clusters of the detecting sensors aggregated around the targets. The TWCA is a significant improvement over the previous studies including our previous rule based cluster association (RBCA) which works only for targets in linear motions and the number of targets being constant during tracking. TWCA can track unknown number of targets in a wide range of non-linear maneuvers with very low computation load and high track accuracy as demonstrated by our simulation.

Square partition‐based node scheduling algorithm for wireless passive sensor networks

SummaryWireless passive sensor networks play an important role in solving the energy limitation of nodes in the Internet of Things, and node scheduling is a significant method used to improve the energy utilization of nodes. In this work, an unused energy model based on analyzing the energy consumption characteristics of passive nodes is proposed because no unified model of passive sensor nodes is reported in previous studies. A rapid square partition clustering method is proposed according to the analysis of the relation between the sensing and communication radii of nodes, and the secondary grouping and node scheduling in each cluster are implemented to ensure the coverage rate of networks. Experimental results show that the state distribution of nodes in the proposed algorithm is favorable. The performance of the proposed algorithm is significantly affected by the P ratio between the working and charging powers of nodes. When the value of P is less than 100, the network coverage and connectivity rate are maintained at more than 95% and 90%, respectively, and are both higher than the existing algorithm.

Simple Contending-type MAC Scheme for Wireless Passive Sensor Networks : Throughput Analysis and Optimization

Simple Contending-type MAC Scheme for Wireless Passive Sensor Networks : Throughput Analysis and Optimization

An Energy Efficient MAC Protocol for Wireless Passive Sensor Networks

Medium Access Control (MAC) protocol is one of the key network protocols that ensure Wireless Sensor Networks (WSNs) maintain high performance during communication. MAC protocol design plays an important role in improving the performances of the whole network. First, Wireless Passive Sensor Networks (WPSNs) and MAC protocols are introduced in this paper. Second, some existing MAC protocols are introduced. Sensor MAC (S-MAC) protocol is analyzed and existing improved backoff algorithms are introduced. A new MAC protocol called Improved Sensor MAC (IS-MAC) is then proposed to solve the problem that the contention window (CW) during carrier sense is fixed in S-MAC protocol. IS-MAC protocol is able to adjust CW in terms of network load, so energy consumption can be decreased. Finally, according to the simulation results on NS2, the proposed protocol has better performance in terms of throughput and energy consumption.

Wireless Power Transfer for Distributed Estimation in Wireless Passive Sensor Networks

Recent advances in wireless power transfer (WPT) technology enable over-the-air charging of passive sensor devices and allow sensors to be active on demand without concern of their battery lifetime. This work examines the beam pattern selection and charging power allocation problems for distributed estimation applications in wireless passive sensor networks (WPSNs) that employ WPT to replenish sensors. The charging operation consists of two-phases: an exploration phase and a replenishment-and-transmission phase. In the exploration phase, radio-frequency (RF) energy chargers first scan the network in turn using different beam patterns and sensors that harvest sufficient energy based on these beams emit pilot signals to enable channel estimation at the fusion center. In the replenishment-and-transmission phase, beam patterns and charging powers are first chosen based on the available channel state information (CSI) and then used to emit RF charging signals to replenish the sensors. The sensors utilize the harvested RF energy to make local observations of the underlying parameter of interest and transmit them to the fusion center, where the final estimate is computed. In this paper, the beam pattern selection and charging power allocation are first jointly optimized with the goal of minimizing the mean-square error (MSE) of the final estimate under perfect CSI. For tractability, an MSE upper bound is used as the objective function and the problem is solved efficiently using the block successive upper bound minimization (BSUM) method. The impact of the exploration threshold and duration on the MSE is then examined for the imperfect CSI case. Simulation results demonstrate the effectiveness of the proposed scheme.

무선 수동형 센서 망을 위한 경합형 MAC 방식의 최적 설계

별도의 RF 소스가 센서 노드에게 에너지를 공급하는 무선 수동형 센서 망은 배터리 없이 영원히 동작할 수 있는 망이다. 그러나 영원한 수명에 대한 기대와 달리 무선 수동형 센서 망은 아직 에너지의 희소성, 에너지 수신과 데이타 전송의 동시불가성, 자원 활용의 비효율성 등 많은 문제를 안고 있다. 본 논문에서는 패킷 상실에는 관대하지만 패킷의 적시 전달을 요구하는 서비스를 제공하는 무선 수동형 센서 망을 다룬다. 이러한 망에서 여러 센서 노드들이 하나의 싱크 노드에게 패킷들을 전달하도록 현실적 제약을 인식하여 framed and slotted ALOHA에 기초한 경합형 MAC 방식을 고려한다. 이어서 지리적으로 흩어져있는 센서 노드들이 전송한 패킷들이 경로 손실을 겪어 결국 capture 현상이 빚어질 때 MAC 방식이 얻을 수 있는 망전체 throughput을 조사한다. 특히 두 센서 노드만이 망에 있을 때 망 전체 throughput의 정확한 공식을 closed form으로 도출한다. 마지막으로 설계 parameter들을 조절하여 최대의 망 전체 throughput을 취하도록 경합형 MAC 방식을 최적화한다.

A batteryless temperature sensor based on high temperature sensitive material

The major challenge in wireless sensor networks is the reduction of energy consumption. Passive wireless sensor network is an attractive solution for measuring physical parameters in harsh environment for large range of applications requiring sensing devices with low cost of fabrication, small size and long term measurement stability. Batteryless temperature sensing techniques are an active research field. The approach developed in our work holds a promising future for temperature sensor applications in order to successfully reduce the energy consumption. The temperature sensor presented in this paper is based on the electromagnetic transduction principle using the integration of the high temperature sensitive material into a passive structure. Variation in temperature makes the dielectric constant of this material changing, and such modification induces variation in the resonant frequencies of high-Q whispering-gallery modes (WGM) in the millimeter-wave frequency range. Following the results achieved, the proposed device shows a linear response to the increasing temperature and these variations can be remotely detected from a radar interrogation.

Emerging Needs for Pervasive Passive Wireless Sensor Networks on Aerospace Vehicles

NASA is investigating passive wireless sensor technology to reduce instrumentation mass and volume in ground testing, air flight, and space exploration applications. Vehicle health monitoring systems (VHMS) are desired on all aerospace programs to ensure the safety of the crew and the vehicles. Pervasive passive wireless sensor networks facilitate VHMS on aerospace vehicles. Future wireless sensor networks on board aerospace vehicles will be heterogeneous and will require active and passive network systems. Since much has been published on active wireless sensor networks, this work will focus on the need for passive wireless sensor networks on aerospace vehicles. Several passive wireless technologies such as MEMS, SAW, backscatter, and chipless RFID techniques, have all shown potential to meet the pervasive sensing needs for aerospace VHMS applications. A SAW VHMS application will be presented. In addition, application areas including ground testing, hypersonic aircraft and spacecraft will be explored along with some of the harsh environments found in aerospace applications.

Nano Watt CMOS temperature sensor

In this paper, an ultra-low power embedded full CMOS temperature sensor based on sub-threshold MOS operation is designed in a 0.18 μm CMOS technology. It focuses on temperature measurement using the difference between the gate-source voltages of transistors operated in sub-threshold region that is proportional to absolute temperature. By using the proposed scheme the wide range supply voltage of 0.6---2.5 V with inaccuracy of +0.55 °C/V and total power consumption of merely 7 nW at 120 °C is achieved. The performance of the sensor is highly linear and the predicted temperature error is ±2 °C in the range of 10---120 °C. The sensor occupies a small area of 67 × 31 μm2. Ultra-low power consumption of the sensor illustrates proper operation for low power applications such as battery powered portable devices, passive RFID tags and wireless sensor network applications.

Determination of RF Source Power in WPSN Using Modulated Backscattering

A wireless sensor network (WSN) is a wireless network consisting of spatially distributed autonomous devices using sensors to cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants, at different locations. During RF transmission energy consumed by critically energy-constrained sensor nodes in a WSN is related to the life time system, but the life time of the system is inversely proportional to the energy consumed by sensor nodes. In that regard, modulated backscattering (MB) is a promising design choice, in which sensor nodes send their data just by switching their antenna impedance and reflecting the incident signal coming from an RF source. Hence wireless passive sensor networks (WPSN) designed to operate using MB do not have the lifetime constraints. In this we are going to investigate the system analytically. To obtain interference-free communication connectivity with the WPSN nodes number of RF sources is determined and analyzed in terms of output power and the transmission frequency of RF sources, network size, RF source and WPSN node characteristics. The results of this paper reveal that communication coverage and RF Source Power can be practically maintained in WPSN through careful selection of design parameters