Magnetic Communication Research Articles

Transmission Coil Group Shaping for Wireless Magnetic Induction MISO Communication System

Abstract Magnetic induction communication is a technology that utilizes magnetic field variations to transmit information. Compared to traditional electromagnetic wave communication, magnetic induction communication performs excellently in environments where electromagnetic waves are difficult to propagate, such as underwater and in soil. However, the current transmission rate of magnetic induction communication is relatively low. The magnetic induction MISO communication system addresses the issue of low transmission rates in cross-medium communication. However, it overlooks the impact of the transmission coil group arrangement on transmission rates. This paper investigates the effect of the transmission coil group arrangement on communication performance and proposes an arc-shaped magnetic induction MISO communication system. The transmission rate performance is analyzed, and the impact of the angle between the transmitting and receiving coils on the reception rate is studied. An expression for the channel gain increment is provided, along with its variation trend with the angle. When the position of the receiving coil is fixed, the expression yields the maximum increment of the shaped channel gain. Simulation results demonstrate that the data transmission rate of the shaped system is approximately 10% higher than that of the unshaped system.

The Inter-channel Interference Cancellation Algorithm for Wireless Magnetic Induction MIMO Communication System Based on Zero-forcing Precoding

Abstract The wireless magnetic induction MIMO system can enhance the data transmission rate in near-field magnetic induction communication, but it also suffers from severe inter-channel interference issues. This paper introduces precoding techniques into the wireless magnetic induction MIMO system, employing the zero-forcing precoding algorithm to eliminate interference between different channels. Firstly, leveraging the characteristic that the channel state of magnetic induction transmit-receive coils is determined solely by the physical parameters of the coils, channel estimation is performed to obtain the channel gain matrix for wireless magnetic induction communication. Subsequently, the obtained channel matrix is subjected to zero-forcing precoding to eliminate interference caused by coupling between different channels. Simulation results indicate that the data transmission rate of the wireless magnetic induction MIMO system is significantly higher after applying zero-forcing precoding compared to the rate without it. Additionally, the system’s data transmission rate decreases as the distance between the transmitting and receiving coils increases.

Full-Duplex Magnetic Induction Communication: Opportunities and Challenges

Full-Duplex Magnetic Induction Communication: Opportunities and Challenges

Minitype Arrays of Acoustically Actuated Magnetoelectric Antennas for Magnetic Induction Communication

The magnetoelectric (ME) antennas rely on the mechanical movement of magnetic dipoles, making it possible to break the constraints on physical dimensions decided by the wavelength of the electromagnetic wavelength. The ME antennas achieve super-low frequency (SLF) communications with a smaller size to provide a novel solution for long-range, underwater, and underground communications; navigation over the horizon; and geological exploring. As a result, further theoretical research and optimization of ME antennas have been an open challenge for decades. Here, we report on minitype arrays of acoustically actuated ME antenna and their more rigorous equivalent circuits. These arrays of ME antenna adjust amplitude-frequency response through the mechanical regulation method. The mechanical parameters of ME antennas in the arrays result in regulating amplitude-frequency response, such as working frequency, fractional bandwidth, and intensity of magnetic induction. Our work provides a more accurate theoretical model and diverse array form over state-of-the-art ME antenna arrays. The frequency, fractional bandwidth, and magnetic induction strength of the ME antenna arrays were achieved to be adjustable in the ranges of 84 to 181 Hz, 3.9% to 8.3%, and two to four times, respectively. In addition, we have calculated the attenuation characteristics of ME antennas and their minitype arrays in seawater. The results show that the ME antenna array described in this manuscript is able to enhance the radiation intensity and information-loading capability, which has a positive potential for application in SLF communication systems.

Backscatter Based Bidirectional Full-Duplex Magnetic Induction Communications

Backscatter Based Bidirectional Full-Duplex Magnetic Induction Communications

Development of an HTS-SQUID-Based Receiver for Long-Range Magnetic Induction Communication in Extreme Environments.

The communication range of magnetic-induction (MI) technology in extreme environments such as underwater or underground is limited by the dipole-like attenuation behavior of the magnetic field as well as the eddy current induced loss in conductive media, and therefore a highly sensitive receiver is generally required. In this work, we propose the use of a highly sensitive superconducting quantum interference device (SQUID) in MI communication and try to provide a comprehensive investigation on developing a SQUID-based receiver for practical MI applications. A portable receiver scheme integrating a SQUID sensor and a coil-based flux transformer was proposed. The high sensitivity and long-range communication capability of the proposed receiver was experimentally demonstrated by spectroscopic measurements and reception experiments on a receiver prototype. Based on the experimental demonstrations, the sensitivity optimization of the proposed scheme was further investigated by simulation studies, which suggest that a communication distance exceeding 100 m and a channel capacity of ∼20 kb/s in underwater environment could be achieved based upon the optimization of the developed prototype. The results presented in this work have highlighted the potential of deploying SQUID sensors for long-range MI applications in extreme environments.

A Rotating-Permanent-Magnet Array for ULF Through-the-Sea Magnetic Communications

To realize magnetic induction (MI) communication through seawater, a rotating-permanent-magnet array (RPMA) operating in the ultralow frequency (ULF) band is proposed. The array consists of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5\times $ </tex-math></inline-formula> 5 cylindrical Nd–Fe–B magnets driven by servo motors. To maximize the transmitting magnetic moment, the motors are controlled to rotate synchronously through network communication. The design of the magnet and array configuration is implemented by analyzing the torque and magnetic moment. Magnetic forces between the array magnets are analyzed by using the equivalent static magnetic dipole model. Permalloy sleeves are used to reduce the influence of magnetic force on the synchronization of magnets. The total transmitting magnetic moment of the RPMA is 360 A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot ~\text{m}^{2}$ </tex-math></inline-formula> , and its power efficiency is 14.4 times higher than the conventional transmitting system using coils. Binary frequency shift keying (BFSK) modulation is realized by switching the rotating speed of the magnets and verified by an indoor test. The equivalent orthogonal horizontal magnetic dipole (HMD) model of the array is used, and the magnetic field distribution in layered media is simulated using FEKO. The calculated MI is 100 fT in the position with a distance of 1 km and a depth of 5 m in the sea. The results of the through-the-sea experiment show that the magnetic field of the RPMA can be detected in a range of 500 m by magnetic inductive sensors immersed at a depth of 5 m in seawater and agree well with the simulated results. Transmission bit rates of 10 and 5 b/s can be achieved in the positions of 60 and 110 m.

Performance analysis and design of quasi-cyclic LDPC codes for underwater magnetic induction communications

Magnetic induction (MI) communication is an effective scheme for underwater wireless communication. In this paper, we aim to design an underwater MI communication system based on Quasi-cyclic LDPC (QC-LDPC) codes. Firstly, for a given QC-LDPC code used in underwater MI communication, we propose a novel algorithm to evaluate its performance, which is named as underwater magnetic induction protograph (UWMIP) extrinsic information transfer algorithm. Furthermore, we present a differential evolution UWMIP (DE-UWMIP) algorithm, which incorporates the differential evolution method and the UWMIP algorithm. By this algorithm, we search the optimized QC-LDPC codes with best distance threshold. Simulation results show that the proposed algorithm is effective and provide a good guidance to design the underwater MI communication system.

Optimal Active and Reconfigurable Meta-Sphere Design for Metamaterial-Enhanced Magnetic Induction Communications

The magnetic induction (MI) technique enables wireless communications in extreme environments. However, the existing MI systems rely on large antennas and high power, which is not suitable for Internet of Things (IoT) and other mobile devices. Although the new metamaterial-enhanced MI ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{M}^{2}\text{I}$ </tex-math></inline-formula> ) technique can theoretically enhance the MI signal by 30 dB, none of the existing real-world systems achieve the performance due to: 1) the inherent metamaterial loss is significant; 2) the complicated metamaterial structure is not optimized; and 3) an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{M}^{2}\text{I}$ </tex-math></inline-formula> system with fixed parameters cannot keep the optimal performance in dynamic environments. In this article, an active and reconfigurable meta-sphere is designed, optimized, and implemented to approach the theoretical <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{M}^{2}\text{I}$ </tex-math></inline-formula> enhancement bound. Specifically, the new <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{M}^{2}\text{I}$ </tex-math></inline-formula> meta-sphere is realized by a spherical array of active and reconfigurable coil units. Given fixed meta-sphere size and power constraints, there exist complicated trade-offs among coil number, coil size, and the power consumption. Based on the theoretical design, the prototype of the active and reconfigurable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{M}^{2}\text{I}$ </tex-math></inline-formula> meta-sphere system is implemented and tested. Significant power gain and range extension are proved through comprehensive analytical deduction, COMSOL Multiphysics-based simulations, and real-world experiments.

Power-Efficient Data Collection Scheme for AUV-Assisted Magnetic Induction and Acoustic Hybrid Internet of Underwater Things

Power efficiency is a big concern in the Internet of Underwater Things (IoUT). The power consumption of underwater acoustic communications is typically in the scale of watts, which may drain the battery of underwater devices quickly. Whereas, the power consumption of underwater magnetic induction (MI) wireless communications is in the scale of milliwatt. Therefore, this article devotes to combine the underwater MI and acoustic communications to form a power-efficient underwater hybrid wireless network. Specifically, we investigate the power-efficient autonomous underwater vehicle (AUV) data collection schemes in an underwater MI and acoustic hybrid sensor network. We propose an alternating anchor nodes selection and flow routing (AANSFR) AUV data collection method, which alternately optimizes the AUV path planning and network data flow routing. The simulation results show that the proposed hybrid data collection scheme can significantly prolong the lifespan of underwater sensor networks.

Magnetic induction communication using toroidal helix coil

Magnetic induction communication using toroidal helix coil

Multi-Frequency Access for Magnetic Induction-Based SWIPT

Magnetic Induction (MI) based transmissions, where the typical applications are wireless power transfer (WPT) and MI communications, have gained substantial attention in recent years. Existing works related to MI based transmissions mainly focus on the case with single resonant frequency. However, from the perspective of practical applications, it is highly demanded to achieve multi-frequency access for MI based transmissions. Although multiple coils can be used to generate additional resonant frequencies, each coil is often with one resonant frequency. In this paper, we develop the Multi-frequency Resonating Compensation (MuReC) coil based Multiple-band, Multiple-Input, and Multiple-Output (MbMIMO) simultaneous wireless information and power transfer (SWIPT), which can generate multiple resonant frequencies with one coil. The access point (AP) is equipped with multiple MuReC coils as well as delivers power and data to single-coil receivers (RXs) with different resonant frequencies. We propose the magnetic beamforming scheme for MuReC-MbMIMO-SWIPT, which aims to minimize the transmit power as well as guarantee the network throughput, total delivered power, and individual requirements of each channel. The beamforming schemes for two special cases of MuReC-MbMIMO-SWIPT, that is, MuReC-MbMIMO-communications and MuReC-MbMIMO-WPT, are also given. The optimal beamforming scheme in closed-form for MuReC-MbMIMO-communications is derived. In addition, the parameter design scheme for MuReC coils, which can support an arbitrary number of resonant frequencies, is developed. Numerical results verify our theoretical analyses and show that MuReC-MbMIMO transmissions and the proposed beamforming schemes can fully use antenna resources and effectively support multi-frequency access.

Bayesian Multidimensional Scaling for Location Awareness in Hybrid-Internet of Underwater Things

Localization of sensor nodes in the internet of underwater things (IoUT) is of considerable significance due to its various applications, such as navigation, data tagging, and detection of underwater objects. Therefore, in this paper, we propose a hybrid Bayesian multidimensional scaling (BMDS) based localization technique that can work on a fully hybrid IoUT network where the nodes can communicate using either optical, magnetic induction, and acoustic technologies. These communication technologies are already used for communication in the underwater environment; however, lacking localization solutions. Optical and magnetic induction communication achieves higher data rates for short communication. On the contrary, acoustic waves provide a low data rate for long-range underwater communication. The proposed method collectively uses optical, magnetic induction, and acoustic communication-based ranging to estimate the underwater sensor nodes' final locations. Moreover, we also analyze the proposed scheme by deriving the hybrid Cramer-Rao lower bound (H-CRLB). Simulation results provide a complete comparative analysis of the proposed method with the literature.

Comparative analysis of magnetic induction based communication techniques for wireless underground sensor networks.

A large range of applications have been identified based upon the communication of underground sensors deeply buried in the soil. The classical electromagnetic wave (EM) approach, which works well for terrestrial communication in air medium, when applied for this underground communication, suffers from significant challenges attributing to signal absorption by rocks, soil, or water contents, highly varying channel condition caused by soil characteristics, and requirement of big antennas. As a strong alternative of EM, various magnetic induction (MI) techniques have been introduced. These techniques basically depend upon the magnetic induction between two coupled coils associated with transceiver sensor nodes. This paper elaborates on three basic MI communication mechanisms i.e. direct MI transmission, MI waveguide transmission, and 3D coil MI communication with detailed discussion of their working mechanism, advantages and limitations. The comparative analysis of these MI techniques with each other as well as with EM wave method will facilitate the users in choosing the best method to offer enhanced transmission range (upto 250 m), reduced path loss (<100 dB), channel reliability, working bandwidth (1–2 kHz), & omni-directional coverage to realize the promising MI-based wireless underground sensor network (WUSN) applications.

Performance Analysis of Multilayer Coil Based MI Waveguide Communication System

In the non-conventional media like underwater and underground, the Radio Frequency (RF) communication technique does not perform well due to large antenna size requirement and high path loss. In such media, magnetic induction (MI) communication technique is very promising due to small coil size and constant channel behavior. Unlike the RF technique, the communication range in MI technique is relatively less. To enhance this range, a waveguide technique is already brought in practice. This technique employs single layer coils to enhance the performance of MI waveguide. To further enhance the system functioning, in this paper, we investigated the performance of multi-layer coil (MLC) antenna based MI waveguide communication system in terms of transmission range, path loss, bit error rate (BER) and bandwidth. Besides, the system performance is quantitatively evaluated in three different non-conventional media viz., dry soil, fresh water and wet soil. As compared with the single layer counterpart, the MLC system shows a significant improvement in transmission range, BER even in loosely coupled scenarios and shows a corresponding reduction in path loss. However, the bandwidth is observed to be low (< 1 KHz). In this analysis, the eddy current effects and parasitic capacitance are compared for single and multi-layer coils. It is observed that the proposed system performs better in dry soil medium due to less medium conductivity.

Pillar recovery using new wireless blasting technology: a case study in Vazante mine, Brazil

The application of explosives has never been considered as a major influencing factor during either the designing of a mine or the selection of the mining method. However, this has changed with the launch of WebGenTM wireless blasting system, which allowed underground mines to exploit their orebody applying methods previously not possible due to limitations imposed by the use of wired detonators. The wireless blasting system is based on magnetic induction communication, and its signal is capable of overcoming hundreds of meters through rock, water, and air, to reach individual primers in the blastholes without any physical connection.A noble application of wireless detonators is being used in Vazante mine, Brazil, an underground zinc mine where ore pillars are left in the mined stope to secure stability and minimize dilution by limiting the hydraulic radius. The recovery of these pillars is financially desirable but involves extra time and costs associated with scaling, backfilling, reinstalling infrastructure, accessing areas previously blasted (less stable), drilling, charging with explosives, and subsequently, firing and mucking out the blasted material with expected high dilution. Applying 100% wireless detonators made it possible to safely preload the pillar together with production blasts before losing access to the area, a method named Temporary Rib Pillar (TRP). After all the stope is mined and the pillar accomplished its objectives, the primers are initiated without neither the need for the extra cycles described previously, nor the need to re-enter the area. Thus, it was possible to reduce the exposure of people and equipment, reduce operational cycles, and increase ore recovery, directly contributing to anticipate the ore production while guaranteeing the safety of the teams involved.

Analysis of the Mutual Impedance of Coils Immersed in Water

Magnetic induction communication and wireless power transmission based on magnetic coupling have significant application prospects in underwater environments. Mutual impedance is a key parameter particularly required for the design of the systems. However, mutual impedance is usually extracted from measurements when the coils are processed, which is obviously not conducive to the system optimization in the design phase. In this paper, a model of the mutual impedance of coils immersed in water is established. The magnetic vector potential is expressed in the form of series by artificially setting a boundary, and then the mutual impedance calculation formula of the coils immersed in water is derived. In the analysis, the effect of the conductivity of water, the excitation frequency, and the number of turns of the coils are mainly taken into account. In addition, the variation of the mutual impedance of coils in air and water with axial displacement is also compared. The models can be used to analyze the coil coupling characteristics in the presence of conductive medium, which is helpful for the design process.

An optimal energy-throughput efficient cross-layer solution using naked mole rat algorithm for wireless underground sensor networks

Wireless Underground Sensor Networks (WUSNs) have emerged as prominent solution for variety of applications such as monitoring of underground pipelines, maintenance of power grids, smart and precision agriculture, sports fields maintenance, keeping check on underground oil leakage and many more. Whereas traditional electromagnetic wave communication mechanism doesn’t work good for such sensor networks, the magnetic induction (MI) technique offers stable communication channel conditions and therefore, is considered better option by researchers. As well as communication protocols are concerned in light of tough underground conditions, cross-layered approach has proven to be better in comparison to conventional layered protocol approach. In this article, a distributed cross-layer solution for MI-operated WUSNs will be proposed, which is based on a novel optimization approach - Naked Mole Rat algorithm (NMRA). This Distributed Energy-Throughput Efficient Cross-Layer solution using NMRA approach, also called as DECN, has been developed for Direct MI communication as well as MI waveguide communication (using relay coils) using the interaction of various layer features to fulfill Quality of Service (QoS) parameters and attain an optimal saving in energy consumption and at the same time, gain in throughput. The simulation results have indicated that significant energy saving, high performance efficiency and reliable channel communication are achieved with the proposed cross-layered approach for WUSNs.

Design of filamentary planar spiral coils with enhanced channel model for magnetic induction based underground communication

AbstractEarlier researches have proved that the magnetic induction (MI) communication has better performance compared to the electromagnetic (EM) wave propagation in underground (UG) medium as it provides low signal attenuation using small MI coils. In general, non‐planar coils are employed as transceivers in the MI UG communication and their performance is dependent on coil parameters. The disadvantages of non‐planar coils are their bulkiness and limited transmission distance. In this article, a novel idea of using compact filamentary planar spiral coils for MI UG communication is proposed to achieve higher received power at greater transmission distance. An enhanced MI channel model is also proposed to study the medium's influence on MI performance accurately by considering different soil characteristics. Performances of the circular and square coils in the MI system are evaluated based on mutual inductance, path loss, received power, and signal‐to‐noise ratio. The performance comparison suggests that the filamentary planar spiral square coil MI system achieves 9.22% higher received power than the filamentary planar spiral circular coil MI system. Moreover, the lateral and angular misalignment study shows that square coils are more tolerant to misalignments. For the proposed filamentary planar square spiral coil (FPSSC) MI system, the influence of coil parameters, channel parameters, and coil misalignment on the received power was carried out and its least sensitive and most sensitive parameters were identified for further optimization. The performance comparison between the proposed FPSSC MI system and the traditional non‐planar MI coil system suggests that the received power of the proposed system is improved by 47‐49 dBm thus extending the achievable transmission distance.

PCB Planar and Filamentary Planar Spiral Coils based Underground Magnetic Induction Communication with Enhanced Channel Model

A novel idea of using compact filamentary and printed circuit board (PCB) planar spiral coils for the magnetic induction (MI) based underground (UG) communication to achieve high received power and enhanced transmission distance is proposed. In the existing system, non-planar coils were employed as transceivers which lost their function due to their huge size and deployment difficulty. An enhanced MI UG channel model is proposed to accurately investigate the UG medium’s influence on the MI system performance by considering various soil properties that were considered negligible in the earlier models. An analytical approach to calculate self-inductance and mutual inductance of circular and square coils of filamentary planar and PCB planar spiral coils are described from which the communication parameters such as received power, path-loss, and signal-to-ratio are derived. The simulation results reveal that in both filamentary and PCB planar spiral coil, the square shape coil performs better than the circular coil. The filamentary planar spiral square coil (FPSSC) achieves 26.15% higher received power than the PCB planar spiral square coil (PPSSC) due to the former coil’s low resistance and strong mutual coupling. Further, the influence of coil parameters, coil misalignment, and soil properties on the received power is studied for both FPSSC and PPSSC systems, and their major performance influencing parameters are identified. The received power of the proposed FPSSC system exhibits a significant improvement of 31.24% as compared to the traditional non-planar MI coil system.