667 research outputs found
Exploiting Backscatter-Aided Relay Communications with Hybrid Access Model in Device-to-Device Networks
© 2015 IEEE. The backscatter and active RF radios can complement each other and bring potential performance gain. In this paper, we envision a dual-mode radio structure that allows each device to make smart decisions on mode switch between backscatter communications (i.e., the passive mode) or RF communications (i.e., the active mode), according to the channel and energy conditions. The flexibility in mode switching also makes it more complicated for transmission control and network optimization. To exploit the radio diversity gain, we consider a wireless powered device-to-device network of hybrid radios and propose a sum throughput maximization by jointly optimizing energy beamforming and transmission scheduling in two radio modes. We further exploit the user cooperation gain by allowing the passive radios to relay for the active radios. As such, the sum throughput maximization is reformulated into a non-convex. We first present a sub-optimal algorithm based on successive convex approximation, which optimizes the relays' reflection coefficients by iteratively solving semi-definite programs. We also devise a set of heuristic algorithms with reduced computational complexity, which are shown to significantly improve the sum throughput and amenable for practical implementation
Green Cellular Networks: A Survey, Some Research Issues and Challenges
Energy efficiency in cellular networks is a growing concern for cellular
operators to not only maintain profitability, but also to reduce the overall
environment effects. This emerging trend of achieving energy efficiency in
cellular networks is motivating the standardization authorities and network
operators to continuously explore future technologies in order to bring
improvements in the entire network infrastructure. In this article, we present
a brief survey of methods to improve the power efficiency of cellular networks,
explore some research issues and challenges and suggest some techniques to
enable an energy efficient or "green" cellular network. Since base stations
consume a maximum portion of the total energy used in a cellular system, we
will first provide a comprehensive survey on techniques to obtain energy
savings in base stations. Next, we discuss how heterogeneous network deployment
based on micro, pico and femto-cells can be used to achieve this goal. Since
cognitive radio and cooperative relaying are undisputed future technologies in
this regard, we propose a research vision to make these technologies more
energy efficient. Lastly, we explore some broader perspectives in realizing a
"green" cellular network technologyComment: 16 pages, 5 figures, 2 table
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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
Wireless Sensor System for Recycling
The motivation of this thesis was to research and design a prototype model of a wireless sensor network application, to be used as an automated detection infrastructure in recycling environment. The initial idea was to measure the level of the surface in a recycling container and transmit the information through a wireless communication system. The prototype is an initial step for recycling companies for building an automated detection network.
Background of the research strongly supports the accomplished prototype. Study includes description of wireless environment with its problems and challenges. It proceeds with consideration of suitable wireless standards and considers most convenient sensor methods for recycling environment. Eventually document presents the prototype combining the studied entities.
As a result, the prototype has two main operating parts: the wireless communication network and sensors. The network was realized with ZigBee standard by using two radio chips as communication nodes. Second communication node is attached to a recycling container and combined with two ultrasound sensors. This node includes a soft-ware algorithm, which is polling the state of the sensors regularly and deciding if the container is full. The node proceeds to transmission of the information to other communication node. This node is connected to computer and will transmit the information to be used by the recycling organization.fi=OpinnÀytetyö kokotekstinÀ PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=LÀrdomsprov tillgÀngligt som fulltext i PDF-format
High-performance wireless power and data transfer interface for implantable medical devices
Dâimportants progĂšs ont Ă©tĂ© rĂ©alisĂ©s dans le dĂ©veloppement des systĂšmes biomĂ©dicaux implantables grĂące aux derniĂšres avancĂ©es de la microĂ©lectronique et des technologies sans fil. NĂ©anmoins, ces appareils restent difficiles Ă commercialier. Cette situation est due particuliĂšrement Ă un manque de stratĂ©gies de design capable supporter les fonctionnalitĂ©s exigĂ©es, aux limites de miniaturisation, ainsi quâau manque dâinterface sans fil Ă haut dĂ©bit fiable et faible puissance capable de connecter les implants et les pĂ©riphĂ©riques externes. Le nombre de sites de stimulation et/ou dâĂ©lectrodes dâenregistrement retrouvĂ©s dans les derniĂšres interfaces cerveau-ordinateur (IMC) ne cesse de croĂźtre afin dâaugmenter la prĂ©cision de contrĂŽle, et dâamĂ©liorer notre comprĂ©hension des fonctions cĂ©rĂ©brales. Ce nombre est appelĂ© Ă atteindre un millier de site Ă court terme, ce qui exige des dĂ©bits de donnĂ©es atteingnant facilement les 500 Mbps. Ceci Ă©tant dit, ces travaux visent Ă Ă©laborer de nouvelles stratĂ©gies innovantes de conception de dispositifs biomĂ©dicaux implantables afin de repousser les limites mentionnĂ©es ci-dessus. On prĂ©sente de nouvelles techniques faible puissance beaucoup plus performantes pour le transfert dâĂ©nergie et de donnĂ©es sans fil Ă haut dĂ©bit ainsi que lâanalyse et la rĂ©alisation de ces derniĂšres grĂące Ă des prototypes microĂ©lectroniques CMOS. Dans un premier temps, ces travaux exposent notre nouvelle structure multibobine inductive Ă rĂ©sonance prĂ©sentant une puissance sans fil distribuĂ©e uniformĂ©ment pour alimenter des systĂšmes miniatures dâĂ©tude du cerveaux avec des models animaux en ilbertĂ© ainsi que des dispositifs mĂ©dicaux implantbles sans fil qui se caractĂ©risent par une capacitĂ© de positionnement libre. La structure propose un lien de rĂ©sonance multibobines inductive, dont le rĂ©sonateur principal est constituĂ© dâune multitude de rĂ©sonateurs identiques disposĂ©s dans une matrice de bobines carrĂ©es. Ces derniĂšres sont connectĂ©es en parallĂšle afin de rĂ©aliser des surfaces de puissance (2D) ainsi quâune chambre dâalimentation (3D). La chambre proposĂ©e utilise deux matrices de rĂ©sonateurs de base, mises face Ă face et connectĂ©s en parallĂšle afin dâobtenir une distribution dâĂ©nergie uniforme en 3D. Chaque surface comprend neuf bobines superposĂ©es, connectĂ©es en parallĂšle et rĂ©ailsĂ©es sur une carte de circuit imprimĂ© deux couches FR4. La chambre dispose dâun mĂ©canisme naturel de localisation de puissance qui facilite sa mise en oeuvre et son fonctionnement. En procĂ©dant ainsi, nous Ă©vitons la nĂ©cessitĂ© dâune dĂ©tection active de lâemplacement de la charge et le contrĂŽle dâalimentation. Notre approche permet Ă cette surface dâalimentation unique de fournir une efficacitĂ© de transfert de puissance (PTE) de 69% et une puissance dĂ©livrĂ©e Ă la charge (PDL) de 120 mW, pour une distance de sĂ©paration de 4 cm, tandis que le prototype de chambre complet fournit un PTE uniforme de 59% et un PDL de 100 mW en 3D, partout Ă lâintĂ©rieur de la chambre avec un volume de chambre de 27 Ă 27 Ă 16 cm3. Une Ă©tape critique avant dâutiliser un dispositif implantable chez les humains consiste Ă vĂ©rifier ses fonctionnalitĂ©s sur des sujets animaux. Par consĂ©quent, la chambre dâĂ©nergie sans fil conçue sera utilisĂ©e afin de caractĂ©riser les performances dâ une interface sans fil de transmisison de donnĂ©es dans un environnement rĂ©aliste in vivo avec positionement libre. Un Ă©metteur-rĂ©cepteur full-duplex (FDT) entiĂšrement intĂ©grĂ© qui se caractĂ©rise par sa faible puissance est conçu pour rĂ©aliser une interfaces bi-directionnelles (stimulation et enregistrement) avec des dĂ©bits asymĂ©triques: des taux de tramnsmission plus Ă©levĂ©s sont nĂ©cessaires pour lâenregistrement Ă©lectrophysiologique multicanal (signaux de liaison montante) alors que les taux moins Ă©levĂ©s sont utilisĂ©s pour la stimulation (les signaux de liaison descendante). LâĂ©metteur (TX) et le rĂ©cepteur (RX) se partagent une seule antenne afin de rĂ©duire la taille de lâimplant. LâĂ©metteur utilise la radio ultra-large bande par impulsions (IR-UWB) basĂ©e sur lâapproche edge combining et le RX utilise la bande ISM (Industrielle, Scientifique et MĂ©dicale) de frĂ©quence central 2.4 GHz et la modulation on-off-keying (OOK). Une bonne isolation (> 20 dB) est obtenue entre le TX et le RX grĂące Ă 1) la mise en forme les impulsions Ă©mises dans le spectre UWB non rĂ©glementĂ©e (3.1-7 GHz), et 2) le filtrage espace-efficace (Ă©vitant lâutilisation dâun circulateur ou dâun diplexeur) du spectre du lien de communication descendant directement au niveau de lâ amplificateur Ă faible bruit (LNA). LâĂ©metteur UWB 3.1-7 GHz utilise un e modultion OOK ainsi quâune modulation par dĂ©placement de phase (BPSK) Ă seulement 10.8 pJ / bits. Le FDT proposĂ© permet dâatteindre 500 Mbps de dĂ©bit de donnĂ©es en lien montant et 100 Mbps de dĂ©bit de donnĂ©es de lien descendant. Il est entiĂšrement intĂ©grĂ© dans un procĂ©dĂ© TSMC CMOS 0.18 um standard et possĂšde une taille totale de 0.8 mm2. La consommation totale dâĂ©nergie mesurĂ©e est de 10.4 mW (5 mW pour RX et 5.4 mW pour TX au taux de 500 Mbps).In recent years, there has been major progress on implantable biomedical systems that support most of the functionalities of wireless implantable devices. Nevertheless, these devices remain mostly restricted to be commercialized, in part due to weakness of a straightforward design to support the required functionalities, limitation on miniaturization, and lack of a reliable low-power high data rate interface between implants and external devices. This research provides novel strategies on the design of implantable biomedical devices that addresses these limitations by presenting analysis and techniques for wireless power transfer and efficient data transfer. The first part of this research includes our proposed novel resonance-based multicoil inductive power link structure with uniform power distribution to wirelessly power up smart animal research systems and implanted medical devices with high power efficiency and free positioning capability. The proposed structure consists of a multicoil resonance inductive link, which primary resonator array is made of several identical resonators enclosed in a scalable array of overlapping square coils that are connected in parallel and arranged in power surface (2D) and power chamber (3D) configurations. The proposed chamber uses two arrays of primary resonators, facing each other, and connected in parallel to achieve uniform power distribution in 3D. Each surface includes 9 overlapped coils connected in parallel and implemented into two layers of FR4 printed circuit board. The chamber features a natural power localization mechanism, which simplifies its implementation and eases its operation by avoiding the need for active detection of the load location and power control mechanisms. A single power surface based on the proposed approach can provide a power transfer efficiency (PTE) of 69% and a power delivered to the load (PDL) of 120 mW, for a separation distance of 4 cm, whereas the complete chamber prototype provides a uniform PTE of 59% and a PDL of 100 mW in 3D, everywhere inside the chamber with a chamber size of 27Ă27Ă16 cm3. The second part of this research includes our proposed novel, fully-integrated, low-power fullduplex transceiver (FDT) to support bi-directional neural interfacing applications (stimulating and recording) with asymmetric data rates: higher rates are required for recording (uplink signals) than stimulation (downlink signals). The transmitter (TX) and receiver (RX) share a single antenna to reduce implant size. The TX uses impulse radio ultra-wide band (IR-UWB) based on an edge combining approach, and the RX uses a novel 2.4-GHz on-off keying (OOK) receiver. Proper isolation (> 20 dB) between the TX and RX path is implemented 1) by shaping the transmitted pulses to fall within the unregulated UWB spectrum (3.1-7 GHz), and 2) by space-efficient filtering (avoiding a circulator or diplexer) of the downlink OOK spectrum in the RX low-noise amplifier (LNA). The UWB 3.1-7 GHz transmitter using OOK and binary phase shift keying (BPSK) modulations at only 10.8 pJ/bit. The proposed FDT provides dual band 500 Mbps TX uplink data rate and 100 Mbps RX downlink data rate. It is fully integrated on standard TSMC 0.18 nm CMOS within a total size of 0.8 mm2. The total power consumption measured 10.4 mW (5 mW for RX and 5.4 mW for TX at the rate of 500 Mbps)
Airborne Wireless Sensor Networks for Airplane Monitoring System
In traditional airplane monitoring system (AMS), data sensed from strain, vibration, ultrasound of structures or temperature, and humidity in cabin environment are transmitted to central data repository via wires. However, drawbacks still exist in wired AMS such as expensive installation and maintenance, and complicated wired connections. In recent years, accumulating interest has been drawn to performing AMS via airborne wireless sensor network (AWSN) system with the advantages of flexibility, low cost, and easy deployment. In this review, we present an overview of AMS and AWSN and demonstrate the requirements of AWSN for AMS particularly. Furthermore, existing wireless hardware prototypes and network communication schemes of AWSN are investigated according to these requirements. This paper will improve the understanding of how the AWSN design under AMS acquires sensor data accurately and carries out network communication efficiently, providing insights into prognostics and health management (PHM) for AMS in future
Neonatal seizure detection based on single-channel EEG: instrumentation and algorithms
Seizure activity in the perinatal period, which constitutes the most common neurological emergency in the neonate, can cause brain disorders later in life or even death depending on their severity. This issue remains unsolved to date, despite the several attempts in tackling it using numerous methods. Therefore, a method is still needed that can enable neonatal cerebral activity monitoring to identify those at risk. Currently, electroencephalography (EEG) and amplitude-integrated EEG (aEEG) have been exploited for the identification of seizures in neonates, however both lack automation. EEG and aEEG are mainly visually analysed, requiring a specific skill set and as a result the presence of an expert on a 24/7 basis, which is not feasible. Additionally, EEG devices employed in neonatal intensive care units (NICU) are mainly designed around adults, meaning that their design specifications are not neonate specific, including their size due to multi-channel requirement in adults - adults minimum requirement is â„ 32 channels, while gold standard in neonatal is equal to 10; they are bulky and occupy significant space in NICU.
This thesis addresses the challenge of reliably, efficiently and effectively detecting seizures in the neonatal brain in a fully automated manner. Two novel instruments and two novel neonatal seizure detection algorithms (SDAs) are presented. The first instrument, named PANACEA, is a high-performance, wireless, wearable and portable multi-instrument, able to record neonatal EEG, as well as a plethora of (bio)signals. This device despite its high-performance characteristics and ability to record EEG, is mostly suggested to be used for the concurrent monitoring of other vital biosignals, such as electrocardiogram (ECG) and respiration, which provide vital information about a neonate's medical condition. The two aforementioned biosignals constitute two of the most important artefacts in the EEG and their concurrent acquisition benefit the SDA by providing information to an artefact removal algorithm. The second instrument, called neoEEG Board, is an ultra-low noise, wireless, portable and high precision neonatal EEG recording instrument. It is able to detect and record minute signals (< 10 nVp) enabling cerebral activity monitoring even from lower layers in the cortex. The neoEEG Board accommodates 8 inputs each one equipped with a patent-pending tunable filter topology, which allows passband formation based on the application. Both the PANACEA and the neoEEG Board are able to host low- to middle-complexity SDAs and they can operate continuously for at least 8 hours on 3-AA batteries.
Along with PANACEA and the neoEEG Board, two novel neonatal SDAs have been developed. The first one, termed G prime-smoothed (G Ì_s), is an on-line, automated, patient-specific, single-feature and single-channel EEG based SDA. The G Ì_s SDA, is enabled by the invention of a novel feature, termed G prime (G Ì) and can be characterised as an energy operator. The trace that the G Ì_s creates, can also be used as a visualisation tool because of its distinct change at a presence of a seizure. Finally, the second SDA is machine learning (ML)-based and uses numerous features and a support vector machine (SVM) classifier. It can be characterised as automated, on-line and patient-independent, and similarly to G Ì_s it makes use of a single-channel EEG. The proposed neonatal SDA introduces the use of the Hilbert-Huang transforms (HHT) in the field of neonatal seizure detection. The HHT analyses the non-linear and non-stationary EEG signal providing information for the signal as it evolves. Through the use of HHT novel features, such as the per intrinsic mode function (IMF) (0-3 Hz) sub-band power, were also employed. Detection rates of this novel neonatal SDA is comparable to multi-channel SDAs.Open Acces
Robust Controller for Delays and Packet Dropout Avoidance in Solar-Power Wireless Network
Solar Wireless Networked Control Systems (SWNCS) are a style of distributed control systems where sensors, actuators, and controllers are interconnected via a wireless communication network. This system setup has the benefit of low cost, flexibility, low weight, no wiring and simplicity of system diagnoses and maintenance. However, it also unavoidably calls some wireless network time delays and packet dropout into the design procedure. Solar lighting system offers a clean environment, therefore able to continue for a long period. SWNCS also offers multi Service infrastructure solution for both developed and undeveloped countries. The system provides wireless controller lighting, wireless communications network (WI-FI/WIMAX), CCTV surveillance, and wireless sensor for weather measurement which are all powered by solar energy
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