139 research outputs found
On-Site and External Energy Harvesting in Underground Wireless
Energy efficiency is vital for uninterrupted long-term operation of wireless underground communication nodes in the field of decision agriculture. In this paper, energy harvesting and wireless power transfer techniques are discussed with applications in underground wireless communications (UWC). Various external wireless power transfer techniques are explored. Moreover, key energy harvesting technologies are presented that utilize available energy sources in the field such as vibration, solar, and wind. In this regard, the Electromagnetic(EM)- and Magnetic Induction(MI)-based approaches are explained. Furthermore, the vibration-based energy harvesting models are reviewed as well. These energy harvesting approaches lead to design of an efficient wireless underground communication system to power underground nodes for prolonged field operation in decision agriculture
Fundamentals of Wireless Information and Power Transfer: From RF Energy Harvester Models to Signal and System Designs
Radio waves carry both energy and information simultaneously. Nevertheless,
Radio-Frequency (RF) transmission of these quantities have traditionally been
treated separately. Currently, we are experiencing a paradigm shift in wireless
network design, namely unifying wireless transmission of information and power
so as to make the best use of the RF spectrum and radiations as well as the
network infrastructure for the dual purpose of communicating and energizing. In
this paper, we review and discuss recent progress on laying the foundations of
the envisioned dual purpose networks by establishing a signal theory and design
for Wireless Information and Power Transmission (WIPT) and identifying the
fundamental tradeoff between conveying information and power wirelessly. We
start with an overview of WIPT challenges and technologies, namely Simultaneous
Wireless Information and Power Transfer (SWIPT),Wirelessly Powered
Communication Network (WPCN), and Wirelessly Powered Backscatter Communication
(WPBC). We then characterize energy harvesters and show how WIPT signal and
system designs crucially revolve around the underlying energy harvester model.
To that end, we highlight three different energy harvester models, namely one
linear model and two nonlinear models, and show how WIPT designs differ for
each of them in single-user and multi-user deployments. Topics discussed
include rate-energy region characterization, transmitter and receiver
architecture, waveform design, modulation, beamforming and input distribution
optimizations, resource allocation, and RF spectrum use. We discuss and check
the validity of the different energy harvester models and the resulting signal
theory and design based on circuit simulations, prototyping and
experimentation. We also point out numerous directions that are promising for
future research.Comment: guest editor-authored tutorial paper submitted to IEEE JSAC special
issue on wireless transmission of information and powe
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Analysis and design of energy harvesting wireless communication systems
Wireless-powered communication is an emerging technology for powering the
large number of miniature devices of the future. In a wireless-powered communication system, low-power sensors extract energy from the incident wireless signals to
power their operations such as information transmission, sensing or reception. Due to sporadic energy availability, however, such a system is fundamentally different from
a traditionally-powered communication system. This dissertation investigates three distinct aspects of wireless-powered communications to get insights on the system operation. First, leveraging concepts from finite-length information theory, an analytical framework is developed for examining wireless-powered communications with short packets, i.e., in the finite blocklength regime. This is relevant as remotely-powered communications may entail short packets due to small payloads, low-latency requirements, or limited energy to support a longer transmission. Second, using a stochastic geometry framework, an analytical model is developed for characterizing the performance of wireless-powered communications in the millimeter wave (mmWave) band. The proposed model incorporates the key features of mmWave systems such as directional beamforming and sensitivity to building blockages. Finally, the power transfer efficiency and the energy efficiency of a wireless-powered communication system aided by massive MIMO is characterized. The broad goal of this dissertation is to better understand wireless-powered communications in the context of the emerging technologies for 5G.Electrical and Computer Engineerin
Towards 6G-Enabled Internet of Things with IRS-Empowered Backscatter-Assisted WPCNs
Wireless powered communication networks (WPCNs) are expected to play a key role in the forthcoming 6G systems. However, they have not yet found their way to large-scale practical implementations due to their inherent shortcomings such as the low efficiency of energy transfer and information transmission. In this thesis, we aim to study the integration of WPCNs with other novel technologies of backscatter communication and intelligent reflecting surface (IRS) to enhance the performance and improve the efficiency of these networks so as to prepare them for being seamlessly fitted into the 6G ecosystem. We first study the incorporation of backscatter communication into conventional WPCNs and investigate the performance of backscatter-assisted WPCNs (BS-WPCNs). We then study the inclusion of IRS into the WPCN environment, where an IRS is used for improving the performance of energy transfer and information transmission in WPCNs. After that, the simultaneous integration of backscatter communication and IRS technologies into WPCNs is investigated, where the analyses show the significant performance gains that can be achieved by this integration
A Comprehensive Survey on RF Energy Harvesting: Applications and Performance Determinants
\ua9 2022 by the authors. Licensee MDPI, Basel, Switzerland.There has been an explosion in research focused on Internet of Things (IoT) devices in recent years, with a broad range of use cases in different domains ranging from industrial automation to business analytics. Being battery-powered, these small devices are expected to last for extended periods (i.e., in some instances up to tens of years) to ensure network longevity and data streams with the required temporal and spatial granularity. It becomes even more critical when IoT devices are installed within a harsh environment where battery replacement/charging is both costly and labour intensive. Recent developments in the energy harvesting paradigm have significantly contributed towards mitigating this critical energy issue by incorporating the renewable energy potentially available within any environment in which a sensor network is deployed. Radio Frequency (RF) energy harvesting is one of the promising approaches being investigated in the research community to address this challenge, conducted by harvesting energy from the incident radio waves from both ambient and dedicated radio sources. A limited number of studies are available covering the state of the art related to specific research topics in this space, but there is a gap in the consolidation of domain knowledge associated with the factors influencing the performance of RF power harvesting systems. Moreover, a number of topics and research challenges affecting the performance of RF harvesting systems are still unreported, which deserve special attention. To this end, this article starts by providing an overview of the different application domains of RF power harvesting outlining their performance requirements and summarizing the RF power harvesting techniques with their associated power densities. It then comprehensively surveys the available literature on the horizons that affect the performance of RF energy harvesting, taking into account the evaluation metrics, power propagation models, rectenna architectures, and MAC protocols for RF energy harvesting. Finally, it summarizes the available literature associated with RF powered networks and highlights the limitations, challenges, and future research directions by synthesizing the research efforts in the field of RF energy harvesting to progress research in this area
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