Browsing by Subject "Energy harvesting"

Now showing 1 - 19 of 19

Open Access
Advanced asynchronous random access protocols
(2020-08) Akyıldız, Talha
Fifth generation wireless systems and beyond require linking an enormous number of simple machine type devices leading to a new wave of interest in massive machine type communications (mMTC). Diﬀerent from the human-centric communication systems, mMTCs are composed of a large number of devices where each user node generates small data blocks sporadically in an unpredictable manner. In such scenarios, traditional multiple access schemes, e.g., time division multiple access or frequency division multiple access, are not suitable because resource allocation and scheduling based approaches cannot be conveniently adopted due to the required complexity and latency, motivating the use of uncoordinated random access (RA) protocols and making asynchronous ALOHA-like solutions ideal candidates for such applications. In this thesis, we consider the design and analysis of advanced asynchronous RA protocols for diﬀerent settings. We ﬁrst study contention resolution ALOHA (CRA) and irregular repetition ALOHA (IRA) protocols with regular and irregular repetition rates on the collision channel where collisions are resolved through successive interference cancellation. We also propose concatenation of packet replicas with some clean parts with IRA, named irregular repetition ALOHA with replica concatenation (IRARC). Secondly, we introduce energy harvesting (EH) into the framework with the motivation of self-sustainability, and study RA protocols with EH nodes. Finally, we propose a generalization of IRA with packet length diversity to improve the system performance further. We present asymptotic analyses of all the proposed RA protocols, and determine the optimal repetition distributions to maximize the system throughput. We also provide a comprehensive set of numerical results for both asymptotic and practical scenarios to further demonstrate the eﬀectiveness of the proposed approaches.
Open Access
Analysis of Coded Slotted ALOHA with energy harvesting nodes for Perfect and Imperfect Packet Recovery Scenarios
(Institute of Electrical and Electronics Engineers, 2023-03-06) Haghighat, Javad; Duman, Tolga Mete
We analyze the performance of Coded Slotted ALOHA (CSA) protocols in scenarios where users are equipped with limited batteries that are recharged through Energy Harvesting (EH). First, we assume a Perfect Packet Recovery Scenario (PPRS) for which the received packets are decoded with no errors when there is no interference. We introduce Battery Outage Probability (BOP) as an extra performance metric; and, we derive the optimal EH-CSA transmission policies, which offer the maximum attainable traffic load while maintaining an asymptotically negligible Packet Loss Ratio (PLR), under specific rate and BOP constraints. We extend our study to Imperfect Packet Recovery Scenario (IPRS) where impairments at the physical layer, including channel estimation and channel decoding errors, will distort messages being passed through the iterative Successive Interference Cancellation (SIC) process. The distorted messages being passed through the SIC process potentially lead to error propagation. In order to track the error propagation process, we define the concept of Accumulated Noise plus Interference Power (ANIP), and analytically track the evolution of its probability distribution. We employ our results to evaluate the bit error rates for different transmission policies for the case of IPRS. We also demonstrate the advantages of the optimal transmission policies through numerical examples for both PPRS and IPRS. Our results show that the optimal EH-CSA policies outperform the policies optimized for standard CSA without EH considerations, and the schemes that are optimal for PPRS are not necessarily optimal for the IPRS case. Furthermore, the EH-CSA optimal policies strictly outperform standard CRDSA when the system is required to support higher traffic loads.
Open Access
Code design for binary energy harvesting channel
(IEEE, 2017) Dabirnia, Mehdi; Duman, Tolga M.
We consider a binary energy harvesting communication system with a finite battery transmitter over a noisy channel, and design explicit and implementable codes based on concatenation of a nonlinear trellis code (NLTC) with an outer low density parity check (LDPC) code. We propose two different decoding methods where the simplified one ignores the memory in the battery state while the more sophisticated one utilizes the memory. Numerical results demonstrate that the designed codes outperform other reference schemes. The results also show the superiority of the improved decoding approach over the naive solution.
Open Access
Continuous triboelectric power harvesting and biochemical sensing inside poly(vinylidene fluoride) hollow fibers using microfluidic droplet generation
(Wiley-Blackwell, 2016-11) Kanik, M.; Marcali, M.; Yunusa, M.; Elbuken, C.; Bayındır, Mehmet
Triboelectric power harvesting and biochemical sensing inside poly(vinylidene fluoride) hollow fibers. Fiber‐based microfluidic energy harvesting system, which is also utilized as self‐powered chemical and biosensor. In vitro device concept demonstrating that triboelectric effect can be used for cell detection.
Open Access
EHPBS: Energy harvesting prediction based scheduling in wireless sensor networks
(IEEE, 2013) Akgun, B.; Aykın, Irmak
The clustering algorithms designed for traditional sensor networks have been adapted for energy harvesting sensor networks (EHWSN). However, in these algorithms, the intra-cluster MAC protocols to be used were either not defined at all or they were TDMA based. These TDMA based MAC protocols are not specified except for the fact that cluster heads assign time slots to their members in a random manner. In this paper, we will modify this TDMA based scheduling as follows: members will request a time slot depending on their energy prediction and the cluster heads will assign these slots to members. This method will increase the network lifetime. The proof will be given with simulations. © 2013 IEEE.
Open Access
Energy harvesting and wireless power transfer enabled wireless networks
(Elsevier, 2020) Duman, Tolga M.; Zhao, N.; Nallanathan, A.; Chen, Y.; Pan, M.
Development of wireless communication networks, connected devices, and improvement of Internet of Things (IoT) will deeply impact in every aspect of human life. In future mobile systems, a tremendous number of low-power wireless devices will exist within the densely deployed heterogeneous networks. One key challenge from the growing demand in wireless applications is a sufficient and flexible energy supply. Hence, a natural spin from the traditional and limited energy sources to alternative energy sources is a natural step to supply the exponential growth of energy demand of the mankind. Recently, energy harvesting (EH) has emerged as an important method to provide a power supply for green self-sufficient wireless nodes, in which the energy captured from intentional or ambient sources can be collected to replenish the batteries. Besides, EH has been investigated as a promising technology to overcome the energy scarcity problem in energy constrained wireless communication systems, especially for wireless networks with fixed energy supplies. Compared with conventional EH sources such as solar, wind, vibration, thermoelectric effects or other physical phenomena, which rely on external energy sources that are not components of communication networks, a new operation of EH which collects energy from ambient radio-frequency (RF) signals has been proposed. As RF signals are commonly used as a vehicle for transmitting information in wireless networks, simultaneous wireless information and power transfer (SWIPT) has become an emerging technique attracting great attention from both academia and industry. Towards this end, this special issue includes a collection of 24 papers, and we aim to disseminate the latest research and innovations on energy harvesting and wireless power transfer enabled wireless networks.
Open Access
Energy harvesting irregular repetition ALOHA with replica concatenation
(IEEE, 2021) Akyıldız, Talha; Demirhan, U.; Duman, Tolga M.
In this paper, we consider an asynchronous random access scheme called irregular repetition ALOHA (IRA) as a generalization of contention resolution ALOHA (CRA) with varying repetitions. We present an asymptotic performance analysis of CRA and IRA on the collision channel for regular and irregular repetition rates. We also propose an improvement by merging the clean parts of packet replicas in partial collisions, and extend our analysis to this scenario as well. Specific designs of repetition distributions based on the new analysis show that the optimized solutions of irregular repetition slotted ALOHA (IRSA) perform well in both IRA and the enhanced scheme, and they considerably outperform the regular repetition distributions. We also introduce energy harvesting (EH) to both schemes as a practical and sustainable adaptation, where users are able to harvest energy and store it in their finite-capacity batteries. We model the battery state by a discrete-time Markov chain and derive an optimal transmission policy to maximize the asymptotic performance of the system. We provide comprehensive numerical results for both practical and asymptotic scenarios to verify the validity of the proposed analyses, and illustrate the benefits of the proposed systems.
Open Access
Energy management in energy harvesting wireless sensor nodes with lifetime constraints
(2016-06) Tunç, Çağlar
Advancements in the \Internet of Things (IoT)" concept enables large numbers of low-power wireless sensors and electronic devices to be connected to the Internet and outside world over a wide area wireless network without a need for human interaction. Using rechargeable batteries with energy harvesting to power these wireless sensors has been shown to preserve the self-sustainability and selfsu fficiency of a sensor node and prolong its lifetime, hence the whole network it belongs to. However, it brings the question of how to intelligently manage the energy in the battery so that the node maintains its functionalities by keeping the battery level over zero for an extended duration of time, known as the lifehorizon. We propose a risk-theoretic Markov uid queue model to compute the battery outage probability of a wireless sensor node for a given finite life-horizon. The proposed method enables the performance evaluation of a wide spectrum of energy management policies including those with adaptive sensing rate (or duty cycling). In this model, the node gathers data from the environment according to a Poisson process whose rate is to depend on the instantaneous battery level and/or the state of the energy harvesting process (EHP) which is characterized by a Continuous time Markov Chain (CTMC). Moreover, an engineering methodology is proposed by which optimal threshold-based adaptive sensing rate policies are obtained that maximize the information sensing rate of the sensor node while meeting lifetime constraints given in terms of battery outage probabilities. Numerical results are presented for the validation of the analytical model and also the proposed engineering methodology, using two-state CTMC-based EHPs.
Open Access
Energy-harvesting irregular repetition slotted ALOHA with unit-sized battery
(IEEE, 2018-05) Demirhan, U.; Duman, Tolga M.
We propose an irregular repetition slotted ALOHA (IRSA) based uncoordinated random access scheme for energy harvesting (EH) nodes. Specifically, we consider the case in which each user has a unit- sized battery that is recharged with energy harvested from the environment in a probabilistic manner. We analyze this scheme by deriving asymptotic throughput expressions, and obtain optimized probability distributions for the number of packet replicas for each user. We demonstrate that for the case of IRSA with EH nodes, these optimized distributions perform considerably better than those of slotted ALOHA (SA), contention resolution diversity slotted ALOHA (CRDSA) and IRSA, which do not take into account the EH process, for both asymptotic and finite frame length scenarios.
Open Access
Förster-type nonradiative energy transfer directed from colloidal quantum dots to epitaxial quantum wells for light harvesting applications
(Optical Society of America, 2011) Nizamoğlu, Sedat; Sarı, Emre; Baek J.-H.; Lee I.-H.; Demir, Hilmi Volkan
We report on Frster-type nonradiative energy transfer directed from CdSe/ZnS core/shell quantum dots to InGaN/GaN quantum wells with 69.6% efficiency at 1.527 ns-1 rate at room temperature for potential light harvesting and solar cells applications. © 2011 OSA.
Open Access
Irregular repetition slotted ALOHA with energy harvesting nodes
(2017-07) Demirhan, Umut
The importance of wireless networking schemes originating from ALOHA has rapidly risen with the wide-spread use of Internet, advancements in the communications systems and increasing number of wireless devices. Internet-of-Things and machine-to-machine communications concepts have drawn further attention to ALOHA since it is a low-complexity protocol. However, the classical ALOHA is not e cient and cannot handle massive number of users in an e cient manner. Therefore, many improvements have been proposed for over the years. Irregular Repetition Slotted ALOHA (IRSA) is an advanced ALOHA protocol in which each user sends a variable number of copies of their packets in each xed length medium access control (MAC) frame. The collisions may be resolved via successive interference cancellation (SIC) using the copies that are received cleanly. In this way, asymptotic throughputs close to the maximum normalized throughput value of one on the collision channel may be achieved. In this thesis, to reap the bene ts of IRSA for energy harvesting sensor networks, we propose an IRSA based uncoordinated random access scheme for energy harvesting (EH) nodes. Speci cally, we consider the case in which each user has a nite-sized battery which is recharged in a probabilistic manner in each slot with harvested energy from the environment. We analyze this scheme by deriving asymptotic throughput expressions, and obtain optimized probability distributions for the number of packet replicas for each user. We demonstrate that the optimized distributions perform considerably better than those of slotted ALOHA (SA), contention resolution diversity slotted ALOHA (CRDSA) and plain IRSA which do not take into account EH for both asymptotic and nite frame length scenarios.
Open Access
Irregular repetition slotted ALOHA with energy harvesting nodes
(IEEE, 2019-09) Demirhan, Umut; Duman, Tolga M.
We propose an irregular repetition slotted ALOHA (IRSA) based uncoordinated random access scheme for energy harvesting (EH) nodes. Specifically, we consider the case in which each user has a battery that is recharged with harvested energy from the environment in a probabilistic manner. We analyze this scheme starting with a unit-sized battery at the nodes and extend the analysis to the case of a finite-sized battery. For both scenarios, we derive the asymptotic throughput expressions and obtain the optimized probability distributions for the number of packet replicas of the users. We demonstrate that for the case of IRSA with EH nodes, these optimized distributions perform considerably better than the alternatives, including slotted ALOHA (SA), contention resolution diversity slotted ALOHA (CRDSA), and IRSA, which do not take into account the EH process for both asymptotic and finite frame length scenarios.
Open Access
Linear precoder design for simultaneous information and energy transfer over two-user MIMO interference channels
(Institute of Electrical and Electronics Engineers, 2015) Özçelikkale, A.; Duman, T. M.
Communication strategies that utilize wireless media for simultaneous information and power transfer offer a promising perspective for efficient usage of energy resources. With this motivation, we focus on the design of optimal linear precoders for interference channels utilizing such strategies. We formulate the problem of minimizing the total minimum mean-square error while keeping the energy harvested at the energy receivers above given levels. Our framework leads to a non-convex problem formulation. For point-to-point multiple-input multiple-output channels, we provide a characterization of the optimal solutions under a constraint on the number of transmit antennas. For the general interference scenario, we propose two numerical approaches, one for the single antenna information receivers case, and the other for the general case. We also investigate a hybrid signalling scheme, where the transmitter sends a superposition of two signals: a deterministic signal optimized for energy transfer and an information carrying signal optimized for information and energy transfer. It is illustrated that if hybrid signalling is not incorporated into the transmission scheme, interference can be detrimental to the system performance when the number of antennas at the receivers is low.
Open Access
Markov fluid queue model of an energy harvesting IoT device with adaptive sensing
(Elsevier B.V., 2017) Tunc C.; Akar, N.
Energy management is key in prolonging the lifetime of an energy harvesting Internet of Things (IoT) device with rechargeable batteries. Such an IoT device is required to fulfill its main functionalities, i.e., information sensing and dissemination at an acceptable rate, while keeping the probability that the node first becomes non-operational, i.e., the battery level hits zero the first time within a given finite time horizon, below a desired level. Assuming a finite-state Continuous-Time Markov Chain (CTMC) model for the Energy Harvesting Process (EHP), we propose a risk-theoretic Markov fluid queue model for the computation of first battery outage probabilities in a given finite time horizon. The proposed model enables the performance evaluation of a wide spectrum of energy management policies including those with sensing rates depending on the instantaneous battery level and/or the state of the energy harvesting process. Moreover, an engineering methodology is proposed by which optimal threshold-based adaptive sensing policies are obtained that maximize the information sensing rate of the IoT device while meeting a Quality of Service (QoS) constraint given in terms of first battery outage probabilities. Numerical results are presented for the validation of the analytical model and also the proposed engineering methodology, using a two-state CTMC-based EHP.
Open Access
Nanostructured materials and devices for sensing and energy harvesting applications
(2015-08) Kanık, Mehmet
A closer look into the fundamental challenges of the modern world reveals that the increasing demand for energy threatens the evolution of science and technology. Energy-efficiency is thus a fundamental issue in engineering nano-devices. An important path to achieve high efficiency is to convert the mechanical energy into electrical energy using piezoelectric and triboelectric energy harvesting circuitries, hence enabling self-powered systems at nanoscale. The utilization of novel piezoelectric and triboelectric energy harvesting materials introduces the opportunity of manufacturing flexible, wearable and stretchable self-powered devices. In this thesis, we introduced a new fabrication technique, new strategies and practical approaches for developing high performance triboelectric and piezoelectric materials and devices for flexible electronics, artificial skin and energy harvesting applications. The first part of the thesis focuses on the development of piezoelectric nanoribbons. Poly (vinylidene fluoride) and its copolymer Poly (vinylidene fluoride)-co-tri (fluoroethylene) were used to fabricate spontaneously high piezoelectric nanoribbons. We measured the record-high piezoelectric charge coefficient from our ribbons, because the high stress and high temperature used in the fabrication can enhance their properties. In addition, proof of principle devices for energy harvesting and sensing were fabricated using nanoribbons. The achievements in this part of the thesis can be listed as: i) We obtained extraordinary high aspect ratio, globally oriented, polymer encapsulated, and high piezoelectric microribbon and nanoribbon arrays. ii) Due to process conditions (shear stress and temperature) used in thermal fiber drawing, as-produced micro and nanoribbons contain high amount of polar phase without requiring any electrical poling. iii) We developed a new technique for characterizing and analyzing multiferroic characteristics of nano-objects, which consist of parallel evaluation of instrumental, numerical and analytical data. iv) To our knowledge, we achieved the highest piezoelectric charge coefficient from our ribbons in the literature. v) We enhanced stability of the piezoelectric ribbons by increasing the Curie temperature above its melting point due to processing conditions. vi) We observed and explained a new phase transformation mechanism in polymer piezoelectric ribbons. vii) The state-of-the-art ab initio calculations, which explain the phase transformation mechanism of molecules during the fiber drawing with the effect of shear, tensile forces and temperature, were included in detail. The second part is about developing high energy output triboelectric generators. A high performance multi-layered triboelectric generator was developed using chalcogenide nanostructures. This part of the thesis details the following achievements: i) We demonstrated that not only polymer, but also semiconductor chalcogenide materials can be used in triboelectric applications, for the first time. ii) For the first time, we proposed and demonstrated that the fluorination of nanostructured surfaces increases triboelectric performance significantly. iii) We introduced a multi-layered triboelectric generator which is very promising for real applications such as acoustic wave and vibration detection, and energy harvesting with very high power output (0.51 Watt) in comparison with the literature. iv) We used a 3D printing technique to produce our device, which is low-cost and appropriate for rapid prototyping and mass production. v) We explained the device theory for the triboelectric nanogenerator, which aligned well with our experimental results.
Open Access
Rounding corners of nano-square patches for multispectral plasmonic metamaterial absorbers
(OSA - The Optical Society, 2015) Ayas S.; Bakan, G.; Dana, A.
Multispectral metamaterial absorbers based on metal-insulatormetal nano-square patch resonators are studied here. For a geometry consisting of perfectly nano-square patches and vertical sidewalls, double resonances in the visible regime are observed due to simultaneous excitation of electric and magnetic plasmon modes. Although slightly modifying the sizes of the square patches makes the resonance wavelengths simply shift, rounding corners of the square patches results in emergence of a third resonance due to excitation of the circular cavity modes. Sidewall angle of the patches are also observed to affect the absorption spectra significantly. Peak absorption values for the triple resonance structures are strongly affected as the sidewall angle varies from 90 to 50 degrees. Rounded corners and slanted sidewalls are typical imperfections for lithographically fabricated metamaterial structures. The presented results suggest that imperfections caused during fabrication of the top nanostructures must be taken into account when designing metamaterial absorbers. Furthermore, it is shown that these fabrication imperfections can be exploited for improving resonance properties and bandwidths of metamaterials for various potential applications such as solar energy harvesting, thermal emitters, surface enhanced spectroscopies and photodetection. © 2015 Optical Society of America.
Open Access
Scalable fabrication of MXene-PVDF nanocomposite triboelectric fibers via thermal drawing
(2022-12) Hasan, Md Mehdi; Sadeque, Md Sazid Bin; Albasar, Ilgın; Pecenek, H.; Dokan, F. K.; Onses, M. Serdar; Ordu, Mustafa
In the data-driven world, textile is a valuable resource for improving the quality of life through continuous monitoring of daily activities and physiological signals of humans. Triboelectric nanogenerators (TENG) are an attractive option for self-powered sensor development by coupling energy harvesting and sensing ability. In this study, to the best of the knowledge, scalable fabrication of Ti3C2Tx MXene-embedded polyvinylidene fluoride (PVDF) nanocomposite fiber using a thermal drawing process is presented for the first time. The output open circuit voltage and short circuit current show 53% and 58% improvement, respectively, compared to pristine PVDF fiber. The synergistic interaction between the surface termination groups of MXene and polar PVDF polymer enhances the performance of the fiber. The flexibility of the fiber enables the weaving of fabric TENG devices for large-area applications. The fabric TENG (3 × 2 cm2) demonstrates a power density of 40.8 mW m−2 at the matching load of 8 MΩ by maintaining a stable performance over 12 000 cycles. Moreover, the fabric TENG has shown the capability of energy harvesting by operating a digital clock and a calculator. A distributed self-powered sensor for human activities and walking pattern monitoring are demonstrated with the fabric. © 2022 Wiley-VCH GmbH.
Embargo
Scalable fabrication of nanomaterial integrated polymer fibers as self-powered sensors
(2023-12) Hasan, Md Mehdi
Wearable electronics have great potential to revolutionize healthcare by enabling real-time data acquisition and transfer. Textiles, a ubiquitous part of our daily lives, get exposed to a vast amount of biomarkers to provide information on health status and the onset of diseases without compromising comfort. Self-powered sensors have gained interest as these devices do not require any external power to operate but rather can harvest energy to operate the low-power elec-tronics. However, textile-based sensor fabrication requires complex multi-step fabrication protocols. In this study, a one-step fabrication of functional fibers for self-powered sensing using thermal drawing process was investigated. Inte-gration of 2D nanomaterials have significantly improved the performance of the fluoropolymer (PVDF) based triboelectric and piezoelectric fibers. 2D nanoma-terials enhance the output predominantly by the combined effect of interfacial polarization and microcapacitor formation. MXene-PVDF nanocomposite fiber shows β phase increases consistently up to 44% upon 5 wt% MXene addition. The triboelectric fiber demonstrates the capability to harvest energy and biomotion monitoring such as gait analysis. The structural design of MoS2-PVDF piezoelec-tric fiber ensures efficient stress transfer to the piezoelectric domain. Moreover, MoS2 addition increases up to 3 wt% with β phase amount 50% and decreases upon higher MoS2 addition. The Piezoelectric fiber demonstrates the ability to detect physiological signals such as pulse and respiration. The sensors can wirelessly transmit data to store and analyze using a microcontroller unit. The demonstration of large-scale fabrication of the self-powered fiber sensors shows the prospect of the technology as industrially translatable for developing smart clothing.
Open Access
Triboelectric nanogenerators : biomechanical energy harvesting, self powered sensor and wearable applications
(2017-09) Yavuz, Ahmet Faruk
One of the biggest challenges ahead massive advancement of electronic tech-nology is increasing energy consumption. A closer consideration on draining of fossil reserves and rapid development of wearable and portable consumer elec-tronics, inevitable paradigm shift is required towards use of renewable energy sources and self-powered electronic systems respectively. In parallel to this con-sideration, triboelectric nanogenerators have emerged to scavenge energy from ambient environment by using ubiquitous phenomenon of triboelectricity or con-tact electrification in other words. Essentially, triboelectric nanogenerators har-vest mechanical energy into electricity by utilizing triboelectric charge generation and electrostatic induction phenomenon. Accordingly, we developed high perfor-mance biomechanical energy harvesting floor tiles to scavenge human motions into electricity and electrode core-polymer shell structured triboelectric nanogen-erator fibers for wearable applications. Furthermore, new perspectives are intro-duced for fabrications of low-cost, mass producible, large area and flexible tribo-electric nanogenerator structures.