信道質量和服務質量（QoS）是無線體域網的兩個重要挑戰。本文旨在研究信道特性和在保證高吞吐率和低數據弛豫時間前提下探索低功耗WBAN系統策略。本論文的貢獻在於三個方面。首先研究人體信道（HBC）特性。作為IEEE標準802.15.6定義的三種PHY層之一，HBC已經作為體表傳感器通信媒介被廣泛研究。但是，HBC的詳細機理至今仍然不夠明朗，特別是對於那些采用了體內傳感器的應用更少人涉足。因此，我們為此專門預設四種應用場景，並在場景中測量實際信道特性。依據測量結果，我們觀測到數個影響信道質量的因素。其次，我們提出了一種專門針對WBAN的信道建模方法。該方法依賴於對人體組織的直接測量結果，並且此建模方法在建模過程中兼顧體表通信和體內通信。該建模方法包括兩個階段，第一階段是構建人體各部分的子模型，在第二階段調用先前構建之子模型並依賴信號衰減特性來構造上層模型。最終得到的模型包含兩個自變量：頻率和信道長度，從而可應用此模型同時預測不同頻率和不同長度條件下的信道特性。在設計的實驗中，結果表明該模型具有良好的精度，在10 kHz到60 MHz的頻率範圍內，最差的誤差為2.5 dB。除此之外，我們還在一個演示系統中對信道進行了測試，尤其是誤碼率（BER）和信號衰減情形。該測試結果也顯示出該模型所具有的良好預測性。第三，我們提出了一種關註QoS的WBAN系統優化方法。在IEEE標準中定義了數種不同存取模式（Access mode）和存取方式（Access method）。為了提高功率效率，我們著重研究了數據壓縮對系統總功率的影響，另外還對系統吞吐率建立了分析模型。仿真結果顯示，在一定條件下，數據壓縮對功耗降低具有良好功效，另外采用較高數據傳輸速率會對功耗存在改進作用。當數據壓縮模塊的壓縮率超過2倍，而功耗低於收發器的40%時，插入數據壓縮模塊可以確保整個系統消耗更低能源。 / Channel loss and maintaining the Quality of Service (QoS) are two of the major challenges in realizing an effective Wireless Body Area Network (WBAN). This thesis studies the body channel characteristics and proposes a methodology to improve energy efficiency for an entire WBAN system to achieve high throughput and low data latency. Three main contributions are made in this thesis. Firstly, we focus on human body channel (HBC). HBC, as a possible PHY layer for IEEE standards 802.15.6, has been found useful in networking on-body sensors. However, the HBC channel dynamics is not well understood and this is particularly the case when transceivers implanted inside a human body are involved. To this end, channel measurements were performed on real subjects under four different scenarios so that factors affecting channel quality could be identified. Secondly, a channel modelling methodology is proposed for body area network that takes into account the body structure and the dielectric properties of human tissues; this represents the first modelling effort to cover both in-body and on-body communications in vivo. The proposed modelling method composes of two phases: sub-model construction and top-level model construction. The constructed model is a function of two variables, frequency and channel length, enabling channel impedance prediction with respect to either frequency or channel length. Meanwhile, experimental results show that good model accuracy, a maximum error of 2.5 dB, can be achieved in frequencies range from 10 kHz to 60 MHz. In this endeavor, a modified HBC development system was used to measure bit error rate (BER) and signal attenuation during transmission. The measurements show a good match against simulation results and the channel model. Thirdly, a power optimization technique is proposed for the WBAN. The latest IEEE standard 802.15.6 defines several access modes and access methods together with new power management schemes and frame structures. To improve the power efficiency of a body area network, the merit of having data compression was investigated. For this purpose, an analytical model was developed to evaluate the power efficiency of a BAN system. Simulation results show that good power efficiency can be achieved by employing data compression. It is evident that higher data rate can also help improve energy efficiency. When the compression factor is larger than 2, better energy efficiency can be guaranteed by introducing a data processing unit in a sensor node as long as its power consumption is limited to 40% of that of the transceiver unit. / Detailed summary in vernacular field only. / Ai, Yanqing. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 126-135). / Abstracts also in Chinese.

Healthcare is changing, correction ... healthcare is in need of change. The population ageing, the increase in chronic and heart diseases and just the increase in population size will overwhelm the current hospital-centric healthcare. There is a growing interest by individuals to monitor their own physiology. Not only for sport activities, but also to control their own diseases. They are changing from the passive healthcare receiver to a proactive self-healthcare taker. The focus is shifting from hospital centred treatment to a patient-centric healthcare monitoring. Continuous, everyday, wearable monitoring and actuating is part of this change. In this setting, sensors that monitor the heart, blood pressure, movement, brain activity, dopamine levels, and actuators that pump insulin, 'pump' the heart, deliver drugs to specific organs, stimulate the brain are needed as pervasive components in and on the body. They will tend for people's need of self-monitoring and facilitate healthcare delivery. These components around a human body that communicate to sense and act in a coordinated fashion make a Body Area Network (BAN). In most cases, and in our view, a central, more powerful component will act as the coordinator of this network. These networks aim to augment the power to monitor the human body and react to problems discovered with this observation. One key advantage of this system is their overarching view of the whole network. That is, the central component can have an understanding of all the monitored signals and correlate them to better evaluate and react to problems. This is the focus of our thesis. In this document we argue that this multi-parameter correlation of the heterogeneous sensed information is not being handled in BANs. The current view depends exclusively on the applica- tion that is using the network and its understanding of the parameters. This means that every application will oversee the BAN's heterogeneous resources managing them directly without taking into consideration other applications, their needs and knowledge. There are several physiological correlations already known by the medical field. Correlating blood pressure and cross sectional area of blood vessels to calculate blood velocity, estimating oxygen delivery from cardiac output and oxygen saturation, are such examples. This knowledge should be available in a BAN and shared by the several applications that make use of the network. This architecture implies a central component that manages the knowledge and the resources. And this is, in our view, missing in BANs. Our proposal is a middleware layer that abstracts the underlying BAN's resources to the applica- tion, providing instead an information model to be queried. The model describes the correlations for producing new information that the middleware knows about. Naturally, the raw sensed data is also part of the model. The middleware hides the specificities of the nodes that constitute the BAN, by making available their sensed production. Applications are able to query for information attaching requirements to these requests. The middleware is then responsible for satisfying the requests while optimising the resource usage of the BAN.Our architecture proposal is divided in two corresponding layers, one that abstracts the nodes' hardware (hiding node's particularities) and the information layer that describes information available and how it is correlated. A prototype implementation of the architecture was done to illustrate the concept.

Localization inside the human body using radio frequency (RF) transmission is gaining importance in a number of applications such as Wireless Video Capsule Endoscopy. The accuracy of RF localization depends on the technology adopted for this purpose. The two most common RF localization technologies use received signal strength (RSS) and time-of-arrival (TOA). This research presents a comparison of the accuracy of TOA and RSS based localization inside human tissue using computational techniques for simulation of radio propagation inside human tissues. Computer simulation of the propagation of radio waves inside the human body is extremely challenging and computationally intensive. We designed a basic, MATLAB coded, finite difference time-domain (FDTD) for the radio propagation in and around the human body and compared the results obtained from this software with the commonly used and commercially available Finite Element Method (FEM) modeling in ANSYS HFSS. We first show that the FDTD analysis yields comparable results. Then we use the software to simulate the RSS and TOA of the wideband signals propagated inside the human body for RF localization to compare the accuracies of the two methods. We then develop a statistical TOA model using empirical data gathered from these simulations; and, in conjunction with pre-established mathematical models for RSS, we compare the accuracy of each technique with the Cramer-Rao Lower Bound (CRLB) commonly used for calculation of bounds for the performance of localization techniques and the effects of human body movements.

Les avancées technologiques de ces dernières années, combinées au succès avéré et toujours croissant des communications sans fil, ont tout naturellement donné naissance à un nouveau type de réseaux sans fil, communément appelés Body Area networks. A terme, ces réseaux corporels sans fil doivent permettre à un ensemble de senseurs bio-médicaux répartis sur le corps humain de communiquer, soit pour échanger des informations en vue d'un traitement en temps réel du patient, soit pour enregistrer des données physiologiques en vue d'une analyse ultérieure. L’objectif de cette Thèse vise la réduction de la consommation énergétique au niveau des senseurs de sorte à leur garantir une autonomie de quelques mois, voire de quelques années. En réponse à cette contrainte énergétique, une association innovante de deux technologies émergentes est proposée, à savoir une combinaison des transmissions à ultra-large bande aux systèmes à multiples antennes. Une nouvelle architecture pour les réseaux corporels sans fil est donc envisagée pour laquelle les performances doivent être évaluées. Notre principale contribution à cet objectif consiste en la proposition d'une modélisation spatio-temporelle complète du canal de transmission dans le cadre de senseurs répartis autour du corps. Cette modélisation fait appel à la définition de nouveaux modèles, l'élaboration d'outils spécifiques d'extraction de paramètres et une compréhension fine des mécanismes de propagation liés à la proximité du corps humain. Ce manuscrit présente les résultats majeurs de nos recherches en cette matière.

In this thesis, we propose a personal gateway for wireless body area network(WBAN). By using wireless communication and a proper WBAN topology, patients¡¦ physiological signal could be recorded without restricting their mobility. Moreover, integration of several kinds of signals from different sensor nodes in one data platform, personal gateway (PG), can reduce the redundant hardware of individual links as well as the complexity of WBAN. A device for long-term bladder urine pressure measurement is designed as a sensor node of PG. Not only is the design cost reduced, but also the reliability is enhanced by using a 1-atm canceling sensing IA (instrumentation amplifier). Because the urine pressure inside the bladder does not vary drastically, both the sleeping and working modes are required to save the battery power for the long-term observation. To integrate circuits with different supply voltages in PG, a 0.9/1.2/1.8/2.5/3.3/5.0 V wide-range I/O buffer carried out using a typical CMOS process is designed. An input buffer with a logic calibration circuit is used for receiving a low voltage signal. A novel floating N-well circuit is employed to remove the body effect at the output PMOS. Moreover, a dynamic driving detector is included to equalize the turn-on voltages for the output PMOS and NMOS transistors. ZigBee is used as a communication channel in this thesis because of its features, including low power, low complexity, medium range, and medium data rate. The 868/915 MHz mode has lower cost and power consumption than those of 2.4 GHz mode, and the data rate is far enough for WBAN applications. Moreover, lower carrier frequency causes less unnecessary power absorbed by human tissue. Therefore, the ZigBee tranceiver with 868/915 MHz mode is explored. A low power all digital phase lock loop (ADPLL) using a controller which employs a binary frequency searching method is also proposed as a clock generator of PG. Glitch hazards and timing violations which occurred very often in prior ADPLLs are avoided by a novel control method and a new digital-controlled oscillator (DCO) with multiplexers. Besides, the feedback DCO is disabled half a cycle in every two cycles so as to reduce 25% of dynamic power theoretically.

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<p>Progress in miniaturized computing and connectivity has led to a plethora of smart connected electronic devices around humans, leading us towards the era of seamless human-electronics co-operation. In this connected society, radiative communication using electromagnetic fields is the backbone of inter-device connectivity. This unfortunately leads to high power usage as well as physical signals being available for malicious interceptors to snoop. To address the need of security and energy efficiency of inter-device communication for devices on and around the human body, Human Body Communication (HBC) has been proposed. The fundamental philosophy of HBC is to use the human body as a medium - thus being helped and not hurt by the body - for communication between devices. Confinement of a signal within the body implies higher security as well as efficiency. This dissertation is an analysis of these properties of different HBC modalities, through electromagnetic modelling, simulation, and experienced. Electro-quasistatic (EQS) HBC has been explored in significant detail, including a complete theoretical formulation of return path capacitance, as well as a study of inter-body coupling for interference and security management in EQS-HBC. Magnetic modes of HBC have also been analyzed, and compared with its electric counterparts. Finally, a novel HBC technique, GSW-HBC, has been proposed. GSW-HBC or a Goubau line inspired surface wave based HBC, is shown to be a viable, secure and energy efficient alternative to RF wireless communication, leading the search for Gbps communication around the body.</p><p>In reference to IEEE copyrighted material which is used with permission in this thesis, the IEEE does not endorse any of Purdue University's products or services. Internal or personal use of this material is permitted. If interested in reprinting/republishing IEEE copyrighted material for advertising or promotional purposes or for creating new collective works for resale or redistribution, please go to <a href="http://www.ieee.org/publications_standards/publications/rights/rights_link.html" rel="noreferrer" target="_blank">http://www.ieee.org/publications_standards/publications/rights/rights_link.html</a> to learn how to obtain a License from RightsLink.</p>

The smart environments and the connected human seems to be the future of wireless communications. The development of new frequency bands in the millimeter range will allow us to create high data rate communications which will led to the Wireless Body Environment Networks. In this kind of scenarios, it is expected that the user and the environment will interact. In order to develop such new applications, it is necessary to first study the propagation mechanisms and then, the communication channel underlying body centric environments. This thesis treats of channel models for 60 GHz Body Area Networks and more particularly of three kinds of scenarios: (i) the communication between an external base station and a worn node (off-body); (ii) the communication between two worn nodes (on-body); the communication between an external base station and a hand-held device (near-body). An indoor off-body channel model is numerically proposed and implemented. The model is based on the IEEE 802.11ad indoor standard channel at 60 GHz and a fast computation solution of the scattering of a plane wave by a circular cylinder. The model is developed for two orthogonal polarizations and the communications performances are studied. The on-body propagation is studied for two different configurations: line-of-sight and non-line-of-sight communications on the body. These scenarios led to different solutions for the channel knowing as, respectively, Norton’s equations and creeping formulations. These solutions are obtained using simplified geometries which has been experimentally validated. Further, in order to improve the propagation on the human body, a technique using metallic plates has been proposed. This technique has been theoretically studied using Milligton’s equations and experimentally assessed on a flat phantom with the properties of the human skin. The proposed method allows to save up to 20 dB. Finally, the near-body communication scenario has been introduced and studied. The near-body region is extended from 5 to 30 cm away of the user body which corresponds to the arm’s reach and models a handheld device. A numerical algorithm has been proposed to model indoor near-body environments. Also, a special has been given to statistical body shadowing. It has been shown that the fading follows a Two-Wave Diffuse Power distribution. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

The main focus of the work presented in this thesis concerns the development and improvement of Wireless Sensor Networks (WSNs) as well as Wireless Body Area Networks (WBANs). WSN consist of interlinked, wireless devices (nodes) capable of relaying data wirelessly between the nodes. The applications of WSNs are very broad and cover both wireless fitness monitoring systems such as pulse watches or wireless temperature monitoring of buildings, among others. The topics investigated in the work presented within this thesis covers antenna design, wireless propagation environment evaluation and modeling, adaptive antenna control and wireless nodes system design and evaluation. In order to provide an end-user suitable solution for wireless nodes the devices require both small form factor and good performance in order to be competitive on the marked and thus the main part of this thesis focuses on techniques developed and data collected to help achieve these goals.  Several different prototype systems have been developed which have been used to measure data by the Swedish Defence Research Agency (FOI), GKN Aerospace Sweden AB, the Swedish Transport Administration. The system developed with GKN Aerospace was used to do real-time test measurements inside a running RM12 jet engine and required a substantial amount of measurements, environmental modeling and system validation in order to properly design a wireless system suitable for the harsh and fast fading environment inside a jet engine. For FOI improvements were made on a wearable wireless body area network initially developed during the authors master thesis work. Refinements included work on new generation wireless nodes, antenna packaging and node-supported diversity techniques. Work and papers regarding the design of different types of antennas suitable for wireless nodes are presented. The primary constraints on the presented antennas are the limited electrical size. The types of antennas developed include electrically small helix antennas manufactured both on stretchable substrates consisting of a PDMS substrate with Galinstan as the liquid metal conductors, screen printed silver ink for helix antennas and conformal dual patch antennas for wireless sensor nodes. Other standard type antennas are included on the wireless sensors as well.

Pour réduire la consommation d'énergie due aux transmissions radio dans les réseaux de capteurs sans fil, nous proposons une nouvelle approche associant les techniques de précodage MIMO et de relais, appelé précodage distribué max-dmin (DMP). Considérant une source et un relais avec une antenne chacun, et une destination disposant de deux antennes, nous déployons un système MIMO précodé virtuel 2 × 2. Dans ce contexte, nous étudions deux techniques de relais Amplify and Forward (AF) et Decode and Forward (DF). Des comparaisons en termes de taux d'erreur et d'efficacité énergétique par rapport aux systèmes plus classiques comme les codes spatio-temporels distribués ou les combinaisons à gain maximal montrent que notre système est intéressant pour des distances de transmission moyennes (à partir de 16 mètres). Toujours dans l'objectif de maximiser l'efficacité énergétique, nous proposons une allocation de puissance sur les nœuds source et relais. Pour cela, nous dérivons analytiquement les performances du système précodage distribué max-dmin selon le mode AF et DF. Enfin,pour améliorer les performances des systèmes avec décodage au relais (DF), nous proposons un nouveau récepteur (à la destination) qui tient compte des erreurs éventuelles au niveau du relais. / Among various cooperative techniques aiming to reduce power consumption for transmissions between Wireless Body Area Networks (WBAN) and base stations, we present a new approach, named distributed max-dmin precoding (DMP), combining MIMO precoding techniques and relay communications. This protocol is based on the deployment of a virtual 2 × 2 max-dmin precoding over one source, one forwarding relay, both equipped with one antenna and a destination involving 2 antennas. In this context, two kinds of relaying, amplify and forward (AF) or decode and forward (DF) protocols, are investigated. The performance evaluation in terms of Bit-Error-Rate (BER) and energy efficiency are compared with non cooperative techniques and the distributed space time block code (STBC) scheme. Our investigations show that the DMP takes the advantage in terms of energy efficiency from medium transmission distances (after 10 meters). In order to maximise the energy efficiency, we propose a power allocation over the source and the relay. Thus, we derive the performance of our system, both for AF and DF, analytically. To further increase the performance of DF cooperative schemes, we also propose to design a new decoder at the destination that takes profit from side information, namely potential errors at the relay.