Author
Christopher R. Valenta
Other affiliations: Georgia Institute of Technology
Bio: Christopher R. Valenta is an academic researcher from Georgia Tech Research Institute. The author has contributed to research in topics: Lidar & Backscatter. The author has an hindex of 9, co-authored 38 publications receiving 902 citations. Previous affiliations of Christopher R. Valenta include Georgia Institute of Technology.
Papers
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TL;DR: The idea of wireless power transfer (WPT) has been around since the inception of electricity and Nikola Tesla described the freedom to transfer energy between two points without the need for a physical connection to a power source as an?all-surpassing importance to man? as discussed by the authors.
Abstract: The idea of wireless power transfer (WPT) has been around since the inception of electricity. In the late 19th century, Nikola Tesla described the freedom to transfer energy between two points without the need for a physical connection to a power source as an ?all-surpassing importance to man? [1]. A truly wireless device, capable of being remotely powered, not only allows the obvious freedom of movement but also enables devices to be more compact by removing the necessity of a large battery. Applications could leverage this reduction in size and weight to increase the feasibility of concepts such as paper-thin, flexible displays [2], contact-lens-based augmented reality [3], and smart dust [4], among traditional point-to-point power transfer applications. While several methods of wireless power have been introduced since Tesla?s work, including near-field magnetic resonance and inductive coupling, laser-based optical power transmission, and far-field RF/microwave energy transmission, only RF/microwave and laser-based systems are truly long-range methods. While optical power transmission certainly has merit, its mechanisms are outside of the scope of this article and will not be discussed.
745 citations
TL;DR: In this paper, closed-form equations have been developed that calculate the maximum output power and energy-conversion efficiency for an energy-harvesting circuit under power-optimized waveform excitation.
Abstract: Closed-form equations have been developed that calculate the maximum output power and energy-conversion efficiency for an energy-harvesting circuit under power-optimized waveform excitation. The theoretical model predicts how signals with high peak-to-average power ratios increase the output power available at low input powers and decrease the maximum energy-conversion efficiency at high input powers. The model shows agreement to within 0.7 dB with ideal simulated components. Additionally, the model provides a theoretical bound for a realized microwave energy-harvesting circuit prototyped at 5.8 GHz.
86 citations
27 Jun 2013
TL;DR: In this article, the effects of power-optimized waveforms (POWs) on EH circuits were investigated and a relationship between the maximum number of equal energy subcarriers, ripple voltage, and circuit parameters was determined.
Abstract: Power-optimized waveforms (POWs) have been shown to increase the power-conversion efficiency in energy harvesting circuits. This paper is the first attempt to study the effects of a POW on these circuits and determine how its design can affect circuit performance. As an example, a 5.8 GHz single-shunt rectenna was designed to investigate the variation of POW parameters. It was shown that there is an optimal range of subcarrier spacing to maximize POW gain and minimize voltage ripple. Furthermore, a relationship between the maximum number of equal energy subcarriers, ripple voltage, and circuit parameters has been determined.
61 citations
TL;DR: In this article, the authors used transparent conducting films (TCFs) to provide electromagnetic interference (EMI) shielding of aircraft electronics. But, these materials have been used primarily for applications in which optical transparency was required because a human was supposed to be able to see through the material easily (visible spectrum transparency) and electrical conductivity requirements were minimal since most applications were low frequency.
Abstract: Over the past 30 years, optically transparent conductors have revolutionized electronics in many televisions, smartphones, and solar panels. These conductors are materials that simultaneously allow the transmission of light and provide electrical conductivity [1]. Transparent conducting films (TCFs), the most widely used optically transparent conductor, are utilized in smartphone touch screens and flat-panel televisions, among other devices [2]. Since these deposited thin films are typically transparent in the visible spectrum, they can be deposited on aircraft windows to provide electromagnetic interference (EMI) shielding of aircraft electronics. Historically, these materials have been used primarily for applications in which optical transparency was required because a human was supposed to be able to see through the material easily (visible spectrum transparency) and electrical conductivity requirements were minimal since most applications were low frequency [3].
47 citations
03 Apr 2012
TL;DR: In this article, a four-layer FR-4 PCB is presented, which uses a staggered pattern charge collector (SPCC) and a retrodirective array phase modulator (RAPM).
Abstract: Multi-antenna techniques are typically avoided in passive RFID because of the large footprints required. However, the smaller footprints required at microwave frequencies such as the 5.8 GHz industrial, scientific, and medical (ISM) band allow the use of multiple antennas. Two new multi-antenna technologies are featured in this paper to provide power and communications to a passive wireless tag in the 5.8 GHz ISM band. A four-layer FR-4 PCB is presented, which uses a staggered-pattern charge collector (SPCC) and a retrodirective array phase modulator (RAPM). An SPCC is an energy harvester that has two independent antenna arrays. These arrays provide increased gain and beamwidth over a single-antenna source. A RAPM backscatters the reader-transmitted signal directly back to the reader and provides quadrature phase-shift keyed (QPSK) signaling.
46 citations
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01 Jan 2016
TL;DR: In this paper, the authors present the principles of optics electromagnetic theory of propagation interference and diffraction of light, which can be used to find a good book with a cup of coffee in the afternoon, instead of facing with some infectious bugs inside their computer.
Abstract: Thank you for reading principles of optics electromagnetic theory of propagation interference and diffraction of light. As you may know, people have search hundreds times for their favorite novels like this principles of optics electromagnetic theory of propagation interference and diffraction of light, but end up in harmful downloads. Rather than enjoying a good book with a cup of coffee in the afternoon, instead they are facing with some infectious bugs inside their computer.
2,213 citations
TL;DR: Numerical results unveil a substantial performance gain that can be achieved if the resource allocation design is based on the proposed non-linear energy harvesting model instead of the traditional linear model.
Abstract: In this letter, we propose a practical non-linear energy harvesting model and design a resource allocation algorithm for simultaneous wireless information and power transfer (SWIPT) systems. The algorithm design is formulated as a non-convex optimization problem for the maximization of the total harvested power at energy harvesting receivers subject to minimum required signal-to-interference-plus-noise ratios (SINRs) at multiple information receivers. We transform the considered non-convex objective function from sum-of-ratios form into an equivalent objective function in subtractive form, which enables the derivation of an efficient iterative resource allocation algorithm. In each iteration, a rank-constrained semidefinite program (SDP) is solved optimally by SDP relaxation. Numerical results unveil a substantial performance gain that can be achieved if the resource allocation design is based on the proposed non-linear energy harvesting model instead of the traditional linear model.
863 citations
TL;DR: In this paper, the authors proposed a unified MEC-WPT design by considering a wireless powered multiuser MEC system, where a multiantenna access point (AP) integrated with an MEC server broadcasts wireless power to charge multiple users and each user node relies on the harvested energy to execute computation tasks.
Abstract: Mobile-edge computing (MEC) and wireless power transfer (WPT) have been recognized as promising techniques in the Internet of Things era to provide massive low-power wireless devices with enhanced computation capability and sustainable energy supply. In this paper, we propose a unified MEC-WPT design by considering a wireless powered multiuser MEC system, where a multiantenna access point (AP) (integrated with an MEC server) broadcasts wireless power to charge multiple users and each user node relies on the harvested energy to execute computation tasks. With MEC, these users can execute their respective tasks locally by themselves or offload all or part of them to the AP based on a time-division multiple access protocol. Building on the proposed model, we develop an innovative framework to improve the MEC performance, by jointly optimizing the energy transmit beamforming at the AP, the central processing unit frequencies and the numbers of offloaded bits at the users, as well as the time allocation among users. Under this framework, we address a practical scenario where latency-limited computation is required. In this case, we develop an optimal resource allocation scheme that minimizes the AP’s total energy consumption subject to the users’ individual computation latency constraints. Leveraging the state-of-the-art optimization techniques, we derive the optimal solution in a semiclosed form. Numerical results demonstrate the merits of the proposed design over alternative benchmark schemes.
752 citations
TL;DR: The idea of wireless power transfer (WPT) has been around since the inception of electricity and Nikola Tesla described the freedom to transfer energy between two points without the need for a physical connection to a power source as an?all-surpassing importance to man? as discussed by the authors.
Abstract: The idea of wireless power transfer (WPT) has been around since the inception of electricity. In the late 19th century, Nikola Tesla described the freedom to transfer energy between two points without the need for a physical connection to a power source as an ?all-surpassing importance to man? [1]. A truly wireless device, capable of being remotely powered, not only allows the obvious freedom of movement but also enables devices to be more compact by removing the necessity of a large battery. Applications could leverage this reduction in size and weight to increase the feasibility of concepts such as paper-thin, flexible displays [2], contact-lens-based augmented reality [3], and smart dust [4], among traditional point-to-point power transfer applications. While several methods of wireless power have been introduced since Tesla?s work, including near-field magnetic resonance and inductive coupling, laser-based optical power transmission, and far-field RF/microwave energy transmission, only RF/microwave and laser-based systems are truly long-range methods. While optical power transmission certainly has merit, its mechanisms are outside of the scope of this article and will not be discussed.
745 citations
TL;DR: In this paper, the authors present a comprehensive overview of wireless charging techniques, the developments in technical standards, and their recent advances in network applications, with regard to network applications and discuss open issues and challenges in implementing wireless charging technologies.
Abstract: Wireless charging is a technology of transmitting power through an air gap to electrical devices for the purpose of energy replenishment. The recent progress in wireless charging techniques and development of commercial products have provided a promising alternative way to address the energy bottleneck of conventionally portable battery-powered devices. However, the incorporation of wireless charging into the existing wireless communication systems also brings along a series of challenging issues with regard to implementation, scheduling, and power management. In this paper, we present a comprehensive overview of wireless charging techniques, the developments in technical standards, and their recent advances in network applications. In particular, with regard to network applications, we review the static charger scheduling strategies, mobile charger dispatch strategies and wireless charger deployment strategies. Additionally, we discuss open issues and challenges in implementing wireless charging technologies. Finally, we envision some practical future network applications of wireless charging.
718 citations