Two-dimensional Wireless Research Articles

Design optimization of two-dimensional wireless passive force sensor based on finite element analysis

Abstract A two-dimensional wireless and passive sensor based on finite element analysis (FEA) is designed, analyzed, optimized, and tested. The sensor is using the inverse magnetostrictive effect. The sensor included three pieces of sensitive elements that stick to the sensitive area of the elastomer. The FEA mothed is used to assist the design, analysis, and optimization process. The strain-sensitive area of the tension and torque are located in different areas, according to the finite element analysis. When the sensor was fabricated, the sensor’s output performance was tested. The experiment results show that the effective range of tension is 40 N, and the effective range of torque is 4 N·m. The optimized smart structure has a good decoupling effect, which can reduce coupling between dimensions. Finally, the two-dimensional force information can be detected passively and wirelessly.

Multi-Input Physical Layer Network Coding in Two-Dimensional Wireless Multihop Networks

This paper proposes multi-input physical layer network coding (multi-input PLNC) for high speed wireless communication in two-dimensional wireless multihop networks. In the proposed PLNC, all the terminals send their packets simultaneously for the neighboring relays to maximize the network throughput in the first slot, and all the relays also do the same to the neighboring terminals in the second slot. Those simultaneous signal transmissions cause multiple signals to be received at the relays and the terminals. Signal reception in the multi-input PLNC uses multichannel filtering to mitigate the difficulties caused by the multiple signal reception, which enables the two-input PLNC to be applied. In addition, a non-linear precoding is proposed to reduce the computational complexity of the signal detection at the relays and the terminals. The proposed multi-input PLNC makes all the terminals exchange their packets with the neighboring terminals in only two time slots. The performance of the proposed multi-input PLNC is confirmed by computer simulation. The proposed multi-input physical layer network coding achieves much higher network throughput than conventional techniques in a two-dimensional multihop wireless network with 7 terminals. The proposed multi-input physical layer network coding attains superior transmission performance in wireless hexagonal multihop networks, as long as more than 6 antennas are placed on the terminals and the relays.

A Comparative Study on Overall Efficiency of Two-Dimensional Wireless Power Transfer Systems Using Rotational and Directional Methods

Two-dimensional (2-D) wireless power transfer (WPT) systems can be controlled by either the directional method or the rotational method. The rotational method refers to the use of omnidirectional transmitter generating rotational flux regardless of the load positions, while the directional method refers to the use of omnidirectional transmitter generating magnetic flux directly toward the power-consuming load directions. This article compares the overall efficiency of the two methods for 2-D WPT systems. Theoretical analysis reveals that the directional WPT can be more efficient than the rotational WPT with either single or multiple loads when the magnetic field vector is controlled within the feasible zones; and the efficiency difference between the two methods are more significant when the dimensions of the receiver coils are smaller. Both simulation and experimental results are consistent in validating the two discoveries. They indicate that the averaged efficiency of the directional method is at least 5% higher than that of the rotational one.

Two-Dimensional Highly Sensitive Wireless Displacement Sensor With Bilayer Graphene-Based Frequency Selective Surface

In this paper, a two-dimensional wireless displacement sensor with high sensitivity composed of a bilayer graphene-based frequency selective surface (FSS) is proposed. The lengths of the strip-type resonators on the top and bottom layers of the FSS are different and perpendicular to each other. Based on the resonance and polarization characteristics of the FSS, two-dimensional displacement sensing can be realized. It is well validated both in simulation and experiment that the direction of the displacement can be distinguished by the variation trend of the resonant frequencies of the top and bottom layers. In experiment, the measured results of the FSS based wireless displacement sensor in the dynamic range of 5mm show high sensitivity of 280 MHz/mm in x direction and 370 MHz/mm in y direction. Moreover, the excellent mechanical and chemical stability of the multi-layer graphene also makes it suitable for harsh environments, showing good prospects in application.

Connected k-coverage in two-dimensional wireless sensor networks using hexagonal slicing and area stretching

The problem of coverage in two-dimensional (2D) wireless sensor networks is challenging and is still open. Precisely, determining the minimum sensor density (i.e, minimum number of sensors per unit area) that is required to cover a 2D field of interest (FoI), where every point in the field is covered by at least one sensor, is still under investigation. The problem of 2D k-coverage, which requires that every point in a 2D FoI be covered by at least k sensors, where k≥1, is more challenging. In this paper, we attempt to address the 2D connected k-coverage problem, where a 2D FoI is k-covered, while the underlying set of sensors k-covering the field forms a connected network. We propose to solve this problem using an approach based on slicing 2D FoI into convex regular hexagons. Our goal is to achieve k-coverage of a 2D FoI with a minimum number of sensors in order to maximize the network lifetime. First, we compute the minimum sensor density for 2D k-coverage using the regular convex hexagon, which is a 2D paver (i.e., covers a 2D field without gaps or overlaps). Indeed, we found that the regular convex hexagon best assimilates the sensors’ sensing disk with respect to our proposed metric, sensing range usage rate. Second, we derive the ratio of the communication range to the sensing range of the sensors to ensure connected k-coverage. Third, we propose an energy-efficient connected k-coverage protocol based on hexagonal slicing and area stretching. To this end, we formulate a multi-objective optimization problem, which computes an optimum solution to the 2D k-coverage problem that meets two requirements: Maximizing the size of the k-covered area, Ck, so as to minimize the sensor density to k-cover a 2D FoI (Requirement 1) and maximizing the area of the sensor locality, Lk, i.e., the region where at least k sensors are located to k-cover Ck, so as to minimize the interference between sensors (Requirement 2). Fourth, we show various simulation results to substantiate our theoretical analysis. We found a close-to-perfect match between our theoretical and simulation results.

Two-dimensional Wireless Power Relay Plane based on Rectangular Switchable Units

In this paper a two-dimensional wireless relay plane consists of square resonant units is proposed. Power transfer between the transmitting coil and receiver above any unit can be achieved by resonance through the shortest routes on the plane. The self-resonant frequencies of units on the planned route are adjusted to be identical for efficient power transfer, while units beyond the route are isolated from power exchange due to frequency shift. Full wave electromagnetic simulation is executed and analyzed. According to the simulation results, concentrated power transfer can be realized on the power relay plane, and the highest transmission efficiency is 73.93%.

Routing Clustering Protocol for 3D Wireless Sensor Networks Based on Fragile Collection Ant Colony Algorithm

Compared with two-dimensional wireless sensor networks (2DWSNs), three-dimensional wireless sensor networks (3DWSNs) have higher node energy consumption and weaker load balancing. To alleviate these problems, we propose a new multi-hop routing clustering protocol for a wide range of 3DWSNs. In terms of clustering, nodes will run for cluster head (CH) by timing broadcast based on their remaining energy and their average distance from surrounding nodes. Two new identity nodes are added between the CH and the member nodes, the load transfer node responsible for transferring the energy consumption of the CH, and the secondary cluster head node (SCH) acting as the CH for the next round. In order to reduce energy consumption in key node areas, we also enable key nodes to communicate directly with the sink node. In the aspect of routing construction, SN generates the routing table corresponding to each CH through our proposed fragile ant colony algorithm. Because CH and SCH exist at the same time and have a certain replacement order, the SN only needs to obtain the location of each CH when the network is first clustered, and can continuously generate a new routing table corresponding to the CH, which reduces the energy consumption of the network in the routing path construction. We simulate this protocol, LEACH protocol, AZ-SEP protocol, and UCNPD protocol in a three-dimensional environment. The results show that this protocol is better than the other three protocols in terms of network lifetime and network load balance, respectively.

A Two-Dimensional Wireless and Passive Sensor for Stress Monitoring.

A new two-dimensional wireless and passive stress sensor using the inverse magnetostrictive effect is proposed, designed, analyzed, fabricated, and tested in this work. Three pieces of magnetostrictive material are bonded on the surface of a smart elastomer structure base to form the sensor. Using the external load, an amplitude change in the higher-order harmonic signal of the magnetic material is detected (as a result of the passive variation of the magnetic permeability wirelessly). The finite element method (FEM) is used to accomplish the design and analysis process. The strain-sensitive regions of the tension and torque are distributed at different locations, following the FEM analysis. After the fabrication of a sensor prototype, the mechanical output performance is measured. The effective measurement range is 0–40 N and 0–4 N·M under tension and torque, respectively. Finally, the error of the sensor after calibration and decoupling for Fx is 3.4% and for Tx is 4.2% under a compound test load (35 N and 3.5 N·M). The proposed sensor exhibits the merits of being passive and wireless, and has an ingenious structure. This passive and wireless sensor is useful for the long-term detection of mechanical loading within a moving object, and can even potentially be used for tracing dangerous overloads and for preventing implant failures by monitoring the deformation of implants in the human body.

Wireless actuation with functional acoustic surfaces

Miniaturization calls for micro-actuators that can be powered wirelessly and addressed individually. Here, we develop functional surfaces consisting of arrays of acoustically resonant micro-cavities, and we demonstrate their application as two-dimensional wireless actuators. When remotely powered by an acoustic field, the surfaces provide highly directional propulsive forces in fluids through acoustic streaming. A maximal force of ∼0.45 mN is measured on a 4 × 4 mm2 functional surface. The response of the surfaces with bubbles of different sizes is characterized experimentally. This shows a marked peak around the micro-bubbles' resonance frequency, as estimated by both an analytical model and numerical simulations. The strong frequency dependence can be exploited to address different surfaces with different acoustic frequencies, thus achieving wireless actuation with multiple degrees of freedom. The use of the functional surfaces as wireless ready-to-attach actuators is demonstrated by implementing a wireless and bidirectional miniaturized rotary motor, which is 2.6 × 2.6 × 5 mm3 in size and generates a stall torque of ∼0.5 mN·mm. The adoption of micro-structured surfaces as wireless actuators opens new possibilities in the development of miniaturized devices and tools for fluidic environments that are accessible by low intensity ultrasound fields.

Research based on PSO-LSSVM Node Positioning in Wireless Network

In order to improve the positioning accuracy of wireless sensors, and aiming at the parameter optimization problem of least squares support vector machine (LSSVM), a node positioning of particle swarm optimization’s optimized LSSVM sensor is proposed. First, two-dimensional wireless sensor positioning model sample is established, and then LSSVM is adopted to establish node positioning model and PSO algorithm is used to find the optimal parameter. Finally, node’s performance of positioning is tested by simulation experiment. Compared with other positioning method, PSO-LSSVM improves the positioning accuracy of sensor node with some certain practical application value.

Design and performance tests of a LED-based two-dimensional wireless crack propagation sensor

In this study, a wireless light-emitting diode (LED)-based crack sensor is proposed for monitoring two-dimensional crack propagation on concrete structures. This sensor is developed by incorporating a LED optical navigation sensor board (ADNS-2620) into a smart wireless platform (Arduino Pro Mini + XBee). To measure crack propagation, the Arduino Pro Mini sends a signal to the ADNS-2620 to collect a sequence of images reflected from a grid pattern attached on a concrete surface. The normalized cross-correlation method is used to compute the two-dimensional crack propagation using the image sequence. Three different computational approaches were proposed and studied: the moving reference, the absolute reference, and the hybrid reference. The computed crack movements can then be transmitted wirelessly through the XBee modulus to a base station. The design of this sensor is reported herein followed by a series of calibration and performance tests. Results of the performance test on a shake table show that the accuracy of sensor is in the order of 13 µm. A bending test on a concrete beam is further used to illustrate the applicability of the sensor. Results show that the proposed sensor has a potential for monitoring crack propagation of concrete structures. Comparing to a previously developed laser-based crack sensor, the proposed LED-based crack sensor offers a better accuracy but with one third less of power consumption. Copyright © 2015 John Wiley & Sons, Ltd.

Distributed Information Storage and Retrieval in 3-D Sensor Networks With General Topologies

Distributed in-network data-centric processing aims to reduce energy consumed for communication and establish a self-contained data storage, retrieval, aggregation, and query sensor system that focuses more on the data itself rather than the identities of the individual network nodes. Double-ruling-based schemes support efficient in-network data-centric information storage and retrieval, especially for aggregated data, since all data with different types generated in a network can be conveniently retrieved along any single retrieval curve. Previous double-ruling-based research focuses on two-dimensional (2-D) wireless sensor networks where a 2-D planar setting is assumed. With increasing interests in deploying wireless sensors in three-dimensional (3-D) space for various applications, it is urgent yet fundamentally challenging to design double-ruling-based approach in general 3-D sensor networks because double-ruling-based schemes in general have much harder geometric constraints than other distributed in-network data-centric processing schemes. In this research, we propose a geographic location-free double-ruling-based approach for general 3-D sensor networks with possibly complicated topology and geometric shapes. Without the knowledge of the geographic location and the distance bound, a query simply travels along a simple curve with the guaranteed success to retrieve aggregated data through time and space with one or different types across the network. Extensive simulations and comparisons show the proposed scheme with low cost and a balanced traffic load.

Minimizing the number of mobile chargers for large-scale wireless rechargeable sensor networks

Traditional wireless sensor networks (WSNs) are constrained by limited battery energy that powers the sensor nodes, which impedes the large-scale deployment of WSNs. Wireless power transfer technology provides a promising way to solve this problem. With such novel technology, recent works propose to use a single mobile charger (MC) traveling through the network fields to replenish energy to every sensor node so that none of the nodes will run out of energy. These algorithms work well in small-scale networks. In large-scale networks, these algorithms, however, do not work efficiently, especially when the amount of energy the MC can provide is limited. To address this issue, multiple MCs can be used. In this paper, we investigate the minimum MCs problem (MinMCP) for two-dimensional (2D) wireless rechargeable sensor networks (WRSNs), i.e., how to find the minimum number of energy-constrained MCs and design their recharging routes in a 2D WRSN such that each sensor node in the network maintains continuous work, assuming that the energy consumption rate for all sensor nodes are identical. By reduction from the Distance Constrained Vehicle Routing Problem (DVRP), we prove that MinMCP is NP-hard. Then we propose approximation algorithms for this problem. Finally, we conduct extensive simulations to validate the effectiveness of our algorithms.

Optimum sampling in spatial-temporally correlated wireless sensor networks

The optimum sampling in the one- and two-dimensional (1-D and 2-D) wireless sensor networks (WSNs) with spatial-temporally correlated data is studied in this article. The impacts of the node density in the space domain, the sampling rate in the time domain, and the space-time data correlation on the network performance are investigated asymptotically by considering a large network with infinite area but finite node density and finite temporal sampling rate, under the constraint of fixed power per unit area. The impact of space-time sampling on network performances is investigated in two cases. The first case studies the estimations of the space-time samples collected by the sensors, and the samples are discrete in both the space and time domains. The second case estimates an arbitrary data point on the space-time hyperplane by interpolating the discrete samples collected by the sensors. Optimum space-time sampling is obtained by minimizing the mean square error distortion at the network fusion center. The interactions among the various network parameters, such as spatial node density, temporal sampling rate, measurement noise, channel fading, and their impacts on the system performance are quantitatively identified with analytical and numerical studies.

Propagation Analysis Using Plane Coupler for 2D Wireless Power Transmission Systems

A plane coupler has been developed for a two-dimensional (2D) wireless power transmission. This coupler can construct a continuous wireless power transmission system for mobile devices due to its small, light characteristics. This coupler has two elements connected with a 2D waveguide sheet, and coupling capacitances between the elements and the sheet decrease the coupler size by reducing their resonance frequencies. A propagation loss of -10.0dB is obtained using the small 0.025-λ2 coupler. Continuous operation of the mobile device is demonstrated by applying wireless power transmission to the 2D waveguide sheet with the small plane coupler.

Increasing Lifetime of a Two-Dimensional Wireless Sensor Network Using Radio Range Adjustments

Increasing Lifetime of a Two-Dimensional Wireless Sensor Network Using Radio Range Adjustments

Capacity Bounds of Three-Dimensional Wireless Ad Hoc Networks

Network capacity investigation has been intensive in the past few years. A large body of work on wireless network capacity has appeared in the literature. However, so far most of the effort has been made on two-dimensional (2-D) wireless networks only. With the great development of wireless technologies, wireless networks are envisioned to extend from 2-D space to three-dimensional (3-D) space. In this paper, we investigate the throughput capacity of 3-D regular ad hoc networks (RANETs) and of 3-D nonhomogeneous ad hoc networks (NANETs), respectively, by employing a generalized physical model. In 3-D RANETs, we assume that the nodes are regularly placed, while in 3-D NANETs, we consider that the nodes are distributed according to a general Nonhomogeneous Poisson Process (NPP). We find both lower and upper bounds in both types of networks in a broad power propagation regime, i.e., when the path loss exponent is no less than 2.

Optimum Sensor Density in Distortion-Tolerant Wireless Sensor Networks

The optimum sensor node density for one- and two-dimensional (1-D and 2-D) wireless sensor networks (WSNs) with spatial source correlation is studied in this paper. The WSN attempts to reconstruct a spatially correlated signal field by collecting the location-dependent measurements from the distributed sensor nodes. The WSN is designed to minimize the mean square error (MSE) distortion between the original and the reconstructed signals under the constraint of a fixed power per unit area. The impacts of node density and spatial data correlation on the network performance are investigated for both small networks with finite number of nodes, and large networks with infinite area, infinite number of nodes, but finite node density through asymptotic analysis. The interactions among the various network parameters and their impacts on the system performance are quantitatively identified with exact analytical expressions, many of which are in closed-forms. The results provide guidelines on the design of practical WSNs.

Deployment with Sampling Coverage in Three-Dimensional Wireless Sensor Networks

Node deployment is one of important questions in three-dimensional wireless sensor networks(3D WSNs) for the mountain monitoring. In this article, sampling coverage is proposed,and node deployment with sampling coverage is abstracted to mathematical spacing-filling study. The solving method is verified in two-dimensional wireless sensor networks(2D WSNs) firstly,then it is extended to 3D WSNs.Several space-filling polyhedrons are used to fill three-dimensional solid space,and volume entropy is defined to evaluate space-filling perfermance. We can use the minimum nodes to constructe 3D WSNs if choose the vertexes of truncated octahedron to set nodes. That deployment method can both achieve seamless sampling coverage and high connectivity based on computer simulation.

Quasi 2-D Field Reconstruction Using the Conjoint Cylindrical Wave Expansion

Off-the-horizon propagation severely degrades the accuracy of any field reconstruction technique that presupposes a two-dimensional (2-D) wireless channel. Therefore, employing the 2-D cylindrical wave expansion (CWE) to interpolate perimeter channel measurements into a planar region often yields poor results. Here, the CWE is adapted for real-world radio channel measurements by selectively combining the basis functions from two similar CWEs. Using both simulated and experimental measurement data, it is shown that this conjoint CWE yields a more accurate reconstruction than the conventional CWE yet requires no additional measurements. Thereby, this field reconstruction-based channel imaging technique will enable more complete investigations of the wireless channel's spatial behavior and allow researchers to isolate and characterize the actual mechanisms underlying radio wave propagation.