Magneto-inductive Passive Relaying in Arbitrarily Arranged Networks

We consider a wireless sensor network that uses inductive near-field coupling for wireless powering or communication, or for both. The severely limited range of an inductively coupled source-destination pair can be improved using resonant relay devices, which are purely passive in nature. Utilization of such magneto-inductive relays has only been studied for regular network topologies, allowing simplified assumptions on the mutual antenna couplings. In this work we present an analysis of magneto-inductive passive relaying in arbitrarily arranged networks. We find that the resulting channel has characteristics similar to multipath fading: the channel power gain is governed by a non-coherent sum of phasors, resulting in increased frequency selectivity. We propose and study two strategies to increase the channel power gain of random relay networks: i) deactivation of individual relays by open-circuit switching and ii) frequency tuning. The presented results show that both methods improve the utilization of available passive relays, leading to reliable and significant performance gains.Comment: 6 pages, 9 figures. To be presented at the IEEE International Conference on Communications (ICC), Paris, France, May 201

Magneto-Inductive Powering and Uplink of In-Body Microsensors: Feasibility and High-Density Effects

This paper studies magnetic induction for wireless powering and the data uplink of microsensors, in particular for future medical in-body applications. We consider an external massive coil array as power source (1 W) and data sink. For sensor devices at 12 cm distance from the array, e.g. beneath the human skin, we compute a minimum coil size of 150 um assuming 50 nW required chip activation power and operation at 750 MHz. A 275 um coil at the sensor allows for 1 Mbit/s uplink rate. Moreover, we study resonant sensor nodes in dense swarms, a key aspect of envisioned biomedical applications. In particular, we investigate the occurring passive relaying effect and cooperative transmit beamforming in the uplink. We show that the frequency- and location-dependent signal fluctuations in such swarms allow for significant performance gains when utilized with adaptive matching, spectrally-aware signaling and node cooperation. The work is based on a general magneto-inductive MIMO system model, which is introduced first.Comment: 6 pages, to appear at IEEE WCNC 2019. This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

USV charging based on WPT system

With the increasing demand of water and underwater exploration, more and more electric unmanned surface vehicles (USV) are put into use in recent years. However, because of the present battery technology limits, these devices require to be recharged frequently that is a challenging problem taking into account the complex water environment where these equipments are acting. To improve safety and convenience of USV charging a wireless power transfer (WPT) system is proposed in this dissertation. In this case, the boat can be controlled to go to the charging facilities. During charging by the implemented WPT system, the state of charging can be remotely monitored by host computer. The moving control is based on embedded system. The relative position between transmitting coil and receiving coil is supposed to be sensed by magnetic sensor, since the relative position has great impact on transmission efficiency. The remote monitoring software was implemented in the host computer and was developed in LABVIEW. A graphical user interface was developed to control the boat moving and collect the data from the WPT and the boat sensors. The effectiveness of the proposed system was tested for instance in the laboratory environment and in-field tests are also planned in the near future.Com a crescente procura da exploração em ambientes aquáticos e subaquáticos , os veículos elétricos de superfície não tripulados ("electric unmanned surface vehicle" -USV) têm sido cada vez mais utilizados nestes últimos anos. No entanto, devido aos limites atuais relacionados com a tecnologia utilizada nas baterias, os dispositivos precisam de ser recarregados com frequência para poderem operar num ambiente aquático complexo. Para melhorar a segurança e a conveniência do carregamento da bateria de um USV, um sistema para recarregamento da bateria de um barco não tripulado através de transferência de energia sem fios("wireless power transfer" - WPT) é proposto nesta dissertação. Neste caso de estudo, o barco tem a capacidade de ser controlado para chegar a um ponto de recarregamento da bateria, que se encontra fixado por uma doca mecânica. Enquanto o sistema WPT érecarregado, os dados associados ao processo de recarregamento da bateria podem ser monitorizados por um computador host. O controlo da movimentação do barco é baseado num sistema embebido. A posição relativa entre a bobina transmissora e a bobina receptora deve ser detectada pelo sensor magnético, uma vez que a posição relativa tem um grande impacto na eficiência da transmissão. Em termos do computador host, foi utilizado o software LABVIEW para programar a interface que permite controlar o movimento do barco e recolher os dados. Finalmente, a eficácia do sistema proposto foi experimentada e testada num ambiente de laboratório

Low power CMOS IC, biosensor and wireless power transfer techniques for wireless sensor network application

The emerging field of wireless sensor network (WSN) is receiving great attention due to the interest in healthcare. Traditional battery-powered devices suffer from large size, weight and secondary replacement surgery after the battery life-time which is often not desired, especially for an implantable application. Thus an energy harvesting method needs to be investigated. In addition to energy harvesting, the sensor network needs to be low power to extend the wireless power transfer distance and meet the regulation on RF power exposed to human tissue (specific absorption ratio). Also, miniature sensor integration is another challenge since most of the commercial sensors have rigid form or have a bulky size. The objective of this thesis is to provide solutions to the aforementioned challenges

DESIGN AND OPTIMIZATION OF SIMULTANEOUS WIRELESS INFORMATION AND POWER TRANSFER SYSTEMS

The recent trends in the domain of wireless communications indicate severe upcoming challenges, both in terms of infrastructure as well as design of novel techniques. On the other hand, the world population keeps witnessing or hearing about new generations of mobile/wireless technologies within every half to one decade. It is certain the wireless communication systems have enabled the exchange of information without any physical cable(s), however, the dependence of the mobile devices on the power cables still persist. Each passing year unveils several critical challenges related to the increasing capacity and performance needs, power optimization at complex hardware circuitries, mobility of the users, and demand for even better energy efficiency algorithms at the wireless devices. Moreover, an additional issue is raised in the form of continuous battery drainage at these limited-power devices for sufficing their assertive demands. In this regard, optimal performance at any device is heavily constrained by either wired, or an inductive based wireless recharging of the equipment on a continuous basis. This process is very inconvenient and such a problem is foreseen to persist in future, irrespective of the wireless communication method used. Recently, a promising idea for simultaneous wireless radio-frequency (RF) transmission of information and energy came into spotlight during the last decade. This technique does not only guarantee a more flexible recharging alternative, but also ensures its co-existence with any of the existing (RF-based) or alternatively proposed methods of wireless communications, such as visible light communications (VLC) (e.g., Light Fidelity (Li-Fi)), optical communications (e.g., LASER-equipped communication systems), and far-envisioned quantum-based communication systems. In addition, this scheme is expected to cater to the needs of many current and future technologies like wearable devices, sensors used in hazardous areas, 5G and beyond, etc. This Thesis presents a detailed investigation of several interesting scenarios in this direction, specifically concerning design and optimization of such RF-based power transfer systems. The first chapter of this Thesis provides a detailed overview of the considered topic, which serves as the foundation step. The details include the highlights about its main contributions, discussion about the adopted mathematical (optimization) tools, and further refined minutiae about its organization. Following this, a detailed survey on the wireless power transmission (WPT) techniques is provided, which includes the discussion about historical developments of WPT comprising its present forms, consideration of WPT with wireless communications, and its compatibility with the existing techniques. Moreover, a review on various types of RF energy harvesting (EH) modules is incorporated, along with a brief and general overview on the system modeling, the modeling assumptions, and recent industrial considerations. Furthermore, this Thesis work has been divided into three main research topics, as follows. Firstly, the notion of simultaneous wireless information and power transmission (SWIPT) is investigated in conjunction with the cooperative systems framework consisting of single source, multiple relays and multiple users. In this context, several interesting aspects like relay selection, multi-carrier, and resource allocation are considered, along with problem formulations dealing with either maximization of throughput, maximization of harvested energy, or both. Secondly, this Thesis builds up on the idea of transmit precoder design for wireless multigroup multicasting systems in conjunction with SWIPT. Herein, the advantages of adopting separate multicasting and energy precoder designs are illustrated, where we investigate the benefits of multiple antenna transmitters by exploiting the similarities between broadcasting information and wirelessly transferring power. The proposed design does not only facilitates the SWIPT mechanism, but may also serve as a potential candidate to complement the separate waveform designing mechanism with exclusive RF signals meant for information and power transmissions, respectively. Lastly, a novel mechanism is developed to establish a relationship between the SWIPT and cache-enabled cooperative systems. In this direction, benefits of adopting the SWIPT-caching framework are illustrated, with special emphasis on an enhanced rate-energy (R-E) trade-off in contrast to the traditional SWIPT systems. The common notion in the context of SWIPT revolves around the transmission of information, and storage of power. In this vein, the proposed work investigates the system wherein both information and power can be transmitted and stored. The Thesis finally concludes with insights on the future directions and open research challenges associated with the considered framework

Magneto inductive communication system for underwater wireless sensor networks

Underwater wireless sensor networks have found a number of applications in underwater environment monitoring, infrastructure monitoring, military applications and ocean exploration. Among the four possible means of underwater wireless communication, namely acoustic, electromagnetic (EM), magneto-inductive (MI) and optics communication, MI communication enjoys the advantages of being low cost and robust equally in air, water and soil. This dissertation presents design and implementation of a low-power and low-cost MI sensor network node that is suited for long-term deployment of underwater and underground infrastructure monitoring, such as bridge scour and levee scour monitoring. The designed MI sensor node combat the directionality of the single coil MI communication by utilizing 3D coil to both transmit and receive. The presented MI sensor node is tested in air and underwater to show robustness and reliability. The sensor node is designed after thorough analysis and evaluation of various MI challenges such as directionality, short range, decoupling due to mis-alignment of coils, and effect of metal structure. A communication range of 40 m has been achieved by the prototype sensor node. The prototyping cost of a sensor node is less than US$100 and will be drastically reduced at volume production. A novel and an energy efficient medium access control (MAC) protocol based on the carrier sense medium access (CSMA) has also been implemented for the designed sensor node to improve throughput in a dense network --Abstract, page iv

Wireless Power Transfer Technology for Electric Vehicle Charging

In the years 1884-1889, after Nicola Tesla invented "Tesla Coil", wireless power transfer (WPT) technology is in front of the world. WPT technologies can be categorized into three groups: inductive based WPT, magnetic resonate coupling (MRC) based WPT and electromagnetic radiation based WPT. MRC-WPT is advantageous with respect to its high safety and long transmission distance. Thus it plays an important role in the design of wireless electric vehicle (EV) charging systems. The most significant drawback of all WPT systems is the low efficiency of the energy transferred. Most losses happen during the transfer from coil to coil. This thesis proposes a novel coil design and adaptive hardware to improve power transfer efficiency (PTE) in magnetic resonant coupling WPT and mitigate coil misalignment, a crucial roadblock to the acceptance of WPT for EV. In addition, I do some analysis of multiple segmented transmitters design for dynamic wireless EVs charging and propose an adaptive renewable (wind) energy-powered dynamic wireless charging system for EV

Energy harvesting and wireless transfer in sensor network applications: Concepts and experiences

Advances in micro-electronics and miniaturized mechanical systems are redefining the scope and extent of the energy constraints found in battery-operated wireless sensor networks (WSNs). On one hand, ambient energy harvesting may prolong the systems lifetime or possibly enable perpetual operation. On the other hand, wireless energy transfer allows systems to decouple the energy sources from the sensing locations, enabling deployments previously unfeasible. As a result of applying these technologies to WSNs, the assumption of a finite energy budget is replaced with that of potentially infinite, yet intermittent, energy supply, profoundly impacting the design, implementation, and operation of WSNs. This article discusses these aspects by surveying paradigmatic examples of existing solutions in both fields and by reporting on real-world experiences found in the literature. The discussion is instrumental in providing a foundation for selecting the most appropriate energy harvesting or wireless transfer technology based on the application at hand. We conclude by outlining research directions originating from the fundamental change of perspective that energy harvesting and wireless transfer bring about