1,036 research outputs found

    A space division multiplexed free-space-optical communication system that can auto-locate and fully self align with a remote transceiver

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    Free-Space Optical (FSO) systems offer the ability to distribute high speed digital links into remote and rural communities where terrain, installation cost or infrastructure security pose critical hurdles to deployment. A challenge in any point-to-point FSO system is initiating and maintaining optical alignment from the sender to the receiver. In this paper we propose and demonstrate a low-complexity self-aligning FSO prototype that can completely self-align with no requirement for initial manual positioning and could therefore form the opto-mechanical basis for a mesh network of optical transceivers. The prototype utilises off-the-shelf consumer electrical components and a bespoke alignment algorithm. We demonstrate an eight fibre spatially multiplexed link with a loss of 15 dB over 210 m

    Directional Link Management using In-Band Full-Duplex Free Space Optical Transceivers for Aerial Nodes

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    Free-space optical (FSO) communication has become very popular for wireless applications to complement and, in some cases, replace legacy radio-frequency for advantages like unlicensed band, spatial reuse, and enhanced security. Even though FSO can achieve very high bit-rate (tens of Gbps), range limitation due to high attenuation and weather dependency has always restricted its practical implementation to indoor application like data centers and outdoor application like Project Loon. Building-to-building communication, smart cars, and airborne drones are potential futuristic wireless communication sectors for mobile ad-hoc FSO networking. Increasing social media usage demands high-speed mobile connectivity for applications like video call and live video stream on the go. For these scenarios, implementation of in-band full-duplex FSO (IBFD-FSO) transceivers will potentially double the network capacity to improve performance and reliability of the communication link. In this work, we focus on implementing prototypes of FSO transceivers on mobile platform using both off-the-shelf and customized components. Current goal is to implement a prototype of IBFD-FSO transceiver using VCSEL as transmitter and PIN photodiode as receiver at 900 nm wavelength. We are considering atmospheric attenuation, FSO beam propagation model, geometry, and tiling of the components to optimize the link performance while keeping the package low-cost and mobile, ensuring connectivity to mass population. Eventually, our goal is to have communication between multiple airborne drones through IBFD-FSO transceivers by discovering each other and maintaining established link. Applications of this research is not only limited to the conceived idea of smart cities, but it can also have real impact on disaster management in times of wildfire or hurricane

    High-performance wireless power and data transfer interface for implantable medical devices

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    D’importants 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 qu’au manque d’interface 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 d’électrodes d’enregistrement retrouvĂ©s dans les derniĂšres interfaces cerveau-ordinateur (IMC) ne cesse de croĂźtre afin d’augmenter la prĂ©cision de contrĂŽle, et d’amĂ©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 d’énergie et de donnĂ©es sans fil Ă  haut dĂ©bit ainsi que l’analyse 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 d’étude 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© d’une 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 qu’une chambre d’alimentation (3D). La chambre proposĂ©e utilise deux matrices de rĂ©sonateurs de base, mises face Ă  face et connectĂ©s en parallĂšle afin d’obtenir une distribution d’énergie 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 d’un 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© d’une dĂ©tection active de l’emplacement de la charge et le contrĂŽle d’alimentation. Notre approche permet Ă  cette surface d’alimentation 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  l’intĂ©rieur de la chambre avec un volume de chambre de 27 × 27 × 16 cm3. Une Ă©tape critique avant d’utiliser un dispositif implantable chez les humains consiste Ă  vĂ©rifier ses fonctionnalitĂ©s sur des sujets animaux. Par consĂ©quent, la chambre d’énergie sans fil conçue sera utilisĂ©e afin de caractĂ©riser les performances d’ 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 l’enregistrement 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). L’émetteur (TX) et le rĂ©cepteur (RX) se partagent une seule antenne afin de rĂ©duire la taille de l’implant. L’émetteur utilise la radio ultra-large bande par impulsions (IR-UWB) basĂ©e sur l’approche 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 l’utilisation d’un circulateur ou d’un diplexeur) du spectre du lien de communication descendant directement au niveau de l’ amplificateur Ă  faible bruit (LNA). L’émetteur UWB 3.1-7 GHz utilise un e modultion OOK ainsi qu’une modulation par dĂ©placement de phase (BPSK) Ă  seulement 10.8 pJ / bits. Le FDT proposĂ© permet d’atteindre 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 d’énergie 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 27×27×16 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)

    Communications subsystem hardware and software development for the ESTCube-2 nanosatellite

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    One of the most crucial components of satellites is their communications subsystem. Without a functioning radio link, it would be challenging to receive telemetry and payload data from the satellite and send telecommands to it from the ground. ESTCube-2 is a 3U CubeSat from the Estonian Student Satellite Foundation that is expectedto launch in 2022. The mission of ESTCube-2 is to test various payloads inLEO. The primary payload being the plasma brake, similar to the Electric Solar Wind Sail (E-Sail) experiment on ESTCube-1. Due to the critical nature of the satellite communications system, it is essential to start with thorough testing early to reach high reliability by the launch. The goals for this master thesis are to test ESTCube-2 communications subsystem hardware and software, and to create an engineering model, to resolve any issues discovered

    Autonomous Discovery and Maintenance of Mobile Frees-Space-Optical Links

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    Free-Space-Optical (FSO) communication has the potential to play a significant role in future generation wireless networks. It is advantageous in terms of improved spectrum utilization, higher data transfer rate, and lower probability of interception from unwanted sources. FSO communication can provide optical-level wireless communication speeds and can also help solve the wireless capacity problem experienced by the traditional RF-based technologies. Despite these advantages, communications using FSO transceivers require establishment and maintenance of line-of-sight (LOS). We consider autonomous mobile nodes (Unmanned Ground Vehicles or Unmanned Aerial Vehicles), each with one FSO transceiver mounted on a movable head capable of scanning in the horizontal and vertical planes. We propose novel schemes that deal with the problems of automatic discovery, establishment, and maintenance of LOS alignment between these nodes with mechanical steering of the directional FSO transceivers in 2-D and 3-D scenarios. We perform extensive simulations to show the effectiveness of the proposed methods for both neighbor discovery and LOS maintenance. We also present a prototype implementation of such mobile nodes with FSO transceivers. The potency of the neighbor discovery and LOS alignment protocols is evaluated by analyzing the results obtained from both simulations and experiments conducted using the prototype. The results show that, by using such mechanically steerable directional transceivers and the proposed methods, it is possible to establish optical wireless links within practical discovery times and maintain the links in a mobile setting with minimal disruption

    Sensing, communication and illumination with LED lighting systems

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    Plastic Optical Fiber Technology for Reliable Home Networking: Overview and Results of the EU Project POF-ALL

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    The rising performance of broadband connections for residential users, particularly in conjunction with fiber to the home, will present a new challenge for telecom operators in the short and medium terms: how to deliver the high bit rate digital signals with high quality-of-service to all consumer devices scattered inside the building of final users? Among the many different solutions for the home network, we review in this article the use of polymer optical fibers for short-reach and high-capacity optical communications for residential customer premises. POF is an easy-to-install, low-cost, and eye-safe solution for these networks, with the potential of being future-proof. In this article the state of the art in POF technology is presented by summarizing significant results achieved in the European project POF-ALL. Data transmission rates of more than 1 Gb/s over 50+ m and 100 Mb/s over 200+ m of standard step-index POF have been show
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