Dissertations / Theses on the topic 'Wireless Body Area Network (WBAN)'

With the advancements in technology and computing environment capabilities, the number of devices that people carry has increased exponentially. This increase initially occurred as a result of necessity to monitor the human body condition due to chronic diseases, heart problems etc. Later, individuals’ interest was drawn towards self-monitoring their physiology and health care. This is achieved by implanting various sensors that can proactively monitor the human body based on medical necessity and the health condition of the user. Sensors connected on a human body perceive phenomena such as locomotion or heartbeat, and act accordingly to form a Body Area Network. The primary concern of these sensors is to ensure a secure way of communication and coordination among the devices to form a flawless system. A secondary concern is wireless sensor authentication, which ensures trustworthiness and reliable gathering of a user’s data. To address this concern, we designed a secure approach using low cost accelerometers to authenticate sensors in Body Area Networks. To ensure authentication in on-body sensor networks, we need a mechanism which intuitively proves all the communicating nodes are trusted ones. In order to achieve sensor authentication, we used accelerometer data gathered from sensors to distinguish whether or not the devices are carried on waist of same individual’s body. Our approach is focused at analyzing walking patterns recorded from smartphone accelerometers placed in the same location of the user’s body, and we present results showing these sensors record similar pattern.

Dans les réseaux WBAN, les capteurs sont utilisés pour surveiller, collecter et transmettre des signes médicaux et d'autres informations sur le corps humain (EEG, ECG, SpO2, température, etc.) à un nœud principal qu’on appelle « Sink ». Il y a plusieurs préoccupations dans les WBAN, allant de la conception de protocoles de communication fiables et efficaces face à la mobilité du corps humain à une communication faible en consommation énergétique. Les WBAN diffèrent des réseaux de capteurs sans fil typiques à grande échelle et se caractérisent par une mobilité dans le réseau qui suit les mouvements du corps humain et une qualité des liens qui varie en fonction de la posture du porteur. Aussi, la puissance d'émission des capteurs est maintenue faible afin d'améliorer leur autonomie et de réduire l’exposition aux ondes électromagnétiques des porteurs. Par conséquent, compte tenu des effets d’absorption du corps, des réflexions et des interférences, il est difficile de maintenir un lien direct (à un saut) entre le « Sink » et les autres nœuds. La communication multi-sauts représente une alternative viable. Nous avons évalué essentiellement deux primitives de communication: broadcast et converge-cast. Nous avons implémenté différentes stratégies de communication avec le simulateur Omnet++ auquel nous avons intégré le projet Mixim et un modèle de canal réaliste pour un scénario représentatif d'un réseau WBAN. Ce modèle est issu d'une recherche récente de l'informatique biomédicale et décrit les liens entre 7 nœuds, qui appartiennent au même WBAN, et qui sont attachés au corps humain sur la tête, la poitrine, le bras, le poignet, le nombril, la cuisse et la cheville. Les atténuations du signal sur ces liens sont calculées pour 7 postures qui varient entre des positions statiques à fortement mobiles et sont présentées, pour chaque couple de nœuds, sous la forme d’une atténuation moyenne et d’écart-type. Ensuite, nous nous sommes intéressés au problème de broadcast dans WBAN. Nous avons analysé plusieurs stratégies de diffusion inspirées des réseaux DTN avec différents niveaux de connaissance du réseau: des stratégies de type flooding, où les nœuds diffusent les paquets à l'aveugle, et des stratégies basées sur la connaissance du voisinage, où la diffusion est plus contraignante. Nos résultats ont montré que les stratégies de diffusion existantes ne résistent pas face à la mobilité du corps humain et ne peuvent pas être transposées sans des modifications significatives dans un contexte WBAN. Ainsi, nous avons proposé deux nouvelles stratégies de diffusion qui surpassent les stratégies existantes en termes de latence, de couverture du réseau et de la consommation d’énergie des capteurs. Nous avons également analysé la capacité de toutes ces stratégies à assurer l’ordre FIFO (c'est-à-dire les paquets sont reçus dans l'ordre de leur envoi) en les stressant avec différents taux de transmission du nœud « Sink ». Sans exception, les stratégies de diffusion à plat existantes enregistrent une baisse drastique de performance lorsque le taux de transmission augmente. Ainsi, nous avons pu proposer le premier protocole de diffusion inter-couches MAC-réseau, CLBP. Notre protocole exploite la mobilité du corps humain en choisissant soigneusement les liens de communication les plus fiables dans chaque posture. De plus, notre protocole a un mécanisme d'attribution de slots qui réduit la consommation d'énergie, les collisions, l'écoute inactive et la sur-écoute des capteurs. Nous nous sommes également concentrés sur le problème de converge-cast dans les réseaux WBAN. Nous avons adapté à partir des réseaux DTN et WSN des stratégies converge-cast représentatives que nous avons classées en trois catégories: basées sur le modèle du canal, basées sur la diffusion et basées sur multi-chemins. Nous avons étudié trois paramètres: la résilience à la mobilité corporelle, le délai de bout en bout et la consommation d'énergie. [...]
The rapid advances in sensors and ultra-low power wireless communication has enabled a new generation of wireless sensor networks: Wireless Body Area Networks (WBAN). WBAN is a recent challenging area. There are several concerns in this area ranging from energy efficient communication to designing delay efficient protocols that support nodes dynamic induced by human body mobility. In WBAN tiny devices are deployed in/on or around a human body, are able to detect and collect the physiological phenomena of the human body (such as: EEG, ECG, SpO2, etc.), and transmit this information to a collector point (i.e Sink) that will process it, take decisions, alert or record. WBAN differs from typical large-scale wireless sensor networks WSN in many aspects: Network size is limited to a dozen of nodes, in-network mobility follows the body movements and the wireless channel has its specificities. Links have a very short range and a quality that varies with the wearer's posture. The transmission power is kept low to improve devices autonomy and reduce wearers electromagnetic exposition. Consequently, the effects of body absorption, reflections and interference cannot be neglected and it is difficult to maintain a direct link (one-hop) between the Sink and all WBAN nodes. Thus, multi-hop communication represents a viable alternative. In this work we investigate energy-efficient multi-hop communication protocols in WBAN. Our work is part of SMART-BAN Self-organizing Mobility Aware, Reliable and Timely Body Area Networks project. In order to evaluate our communication protocols described in the sequel in a specific WBAN scenario, we implemented them under the Omnet++ simulator that we enriched with the Mixim project and a realistic human body mobility and channel model issued from a recent research on biomedical and health informatics. We are interested in WBAN where sensors are placed on the body. We focus on two communication primitives: broadcast and converge-cast. For the broadcasting problem in WBAN, we analyze several broadcast strategies inspired from the area of DTN then we propose two novel broadcast strategies MBP: Mixed Broadcast Protocol and Optimized Flooding: -MBP (Mixed Broadcast Protocol): We proposed this strategy as a mix between the dissemination-based and knowledge-based approaches. -OptFlood (Optimized Flooding): This strategy takes into account the strengths and weaknesses of the basic strategy Flooding. Optimized Flooding is a revised version of Flooding whose purpose is to keep the good end-to-end delay given by Flooding while lowering energy consumption with the simplest way and the minimum cost. Additionally, we performed investigations of independent interest related to the ability of all the studied strategies to ensure the FIFO order consistency property (i.e. packets are received in the order of their sending) when stressed with various transmission rates. These investigations open new and challenging research directions. With no exception, the existing flat broadcast strategies register a dramatic drop of performances when the transmission rate is superior to 11Kb/s. There, we propose the first network-MAC layer broadcast protocol, CLBP, designed for multi-hop communication and resilient to human body postures and mobility. Our protocol is optimized to exploit the human body mobility by carefully choosing the most reliable communication paths in each studied posture. Moreover, our protocol includes a slot assignment mechanism that reduces the energy consumption, collisions, idle listening and overhearing. Additionally, CLBP includes a synchronization scheme that helps nodes to resynchronize with the Sink on the fly. Our protocol outperforms existing flat broadcast strategies in terms of percentage of covered nodes, energy consumption and correct reception of FIFO-ordered packets and maintains its good performances up to 190Kb/s transmission rates. [...]

Wireless Body Area Network (WBAN) facilitates efficient and cost-effective e-health care and well-being applications. The WBAN has unique challenges and features compared to other Wireless Sensor Networks (WSN). In addition to battery power consumption, the vulnerability and the unpredicted channel behavior of the Medium Access Control (MAC) layer make channel access a serious problem. MAC protocols based on Time Division Multiple Access (TDMA) can improve the reliability and efficiency of WBAN. However, conventional static TDMA techniques adopted by IEEE 802.15.4 and IEEE 802.15.6 do not sufficiently consider the channel status or the buffer requirements of the nodes within heterogeneous contexts. Although there are some solutions that have been proposed to alleviate the effect of the deep fade in WBAN channel by adopting dynamic slot allocation, these solutions still suffer from some reliability and energy efficiency issues and they do not avoid channel deep fading. This thesis presents novel and generic TDMA based techniques to improve WBAN reliability and energy efficiency. The proposed techniques synchronise nodes adaptively whilst tackling their channel and buffer status in normal and emergency contexts. Extensive simulation experiments using various traffic rates and time slot lengths demonstrate that the proposed techniques improve the reliability and the energy efficiency compared to the de-facto standards of WBAN, i.e. the IEEE 802.15.4 and the IEEE 802.15.6. In normal situations, the proposed techniques reduce packet loss up to 61% and 68% compared to the IEEE 802.15.4 and IEEE 802.15.6 respectively. They also reduce energy consumption up to 7.3%. In emergencies, however, the proposed techniques reduce packets loss up to 63.4% and 90% with respect to their counterparts in IEEE 802.15.4 and 802.15.6. The achieved results confirm the significant enhancements made by the developed scheduling techniques to promote the reliability and energy efficiency of WBAN, opening up promising doors towards new horizons and applications.

Due to the recent development and advancement of communication technologies, healthcare industries are becoming more attracted towards information and communication technology services. One of the interesting services is the remote monitoring of patients through the use of a wireless body area network (WBAN), which enables healthcare providers to monitor, diagnose and prescribe patients without being present physically. To develop reliable and exible remote patient monitoring services, in this thesis, the current state-of-the art of WBAN and the limitations of current WBAN technologies are investigated in the healthcare domain. To this end, the relevant background, implementation challenges and limitations of WBAN are overviewed. The in-depth literature survey identifies the lack of a current WBAN architecture in terms of administrative control, static architecture, vendor dependency, traffic priority arrangements, resource utilization, secure data sharing etc. To find a solution to the limitations of WBAN, software-defined networking (SDN) is considered to be one of the promising solutions in this paradigm. However, the incorporation of SDN into WBAN has several challenges in terms of architectural framework, resource optimization and secure data sharing. In this thesis, an SDN-based WBAN (SDWBAN) architecture is proposed to incorporate the functionalities and principles of SDN on top of the traditional WBAN architecture to overcome the existing barriers of WBAN. The proposed communication model of the SDWBAN framework utilizes the sector-based distance (SBD) routing protocol for data packet dissemination. Furthermore, an application classification algorithm is developed to prioritize emergency applications over normal applications. The proposed architecture and communication model have been simulated and experiments are conducted in Castalia 3.2. The simulation outcome demonstrates enhanced performance in terms of the packet delivery rate (PDR) and the latency of the emergency applications in comparison to normal applications. For resource optimization, a mathematical model is developed to optimize the design of the control plane in the proposed SDWBAN framework. The purpose of the model is to reduce the unnecessary wastage of resources and find an optimal relationship among the number of controllers, SDN-enabled switches (SDESWs) and body sensors (BSs) which can potentially maximize network performance. The key factors in the proposed mathematical model encompass the number of controllers, ow resolution time and number of SDESWs and BSs. The specific number of controllers returned by the model is used in the proposed SDWBAN and experiments are conducted in Castalia 3.2. The simulation results reveal that the optimal number of controllers returned by our model produces an acceptable range of PDR and latency. Finally, a secure data-sharing platform is proposed for our SDWBAN framework. The platform is developed based on the cutting-edge blockchain technology and considers multiple entities such as healthcare professionals from various clinics, medical researchers and health insurers etc. The platform is implemented with a proof-of-concept (PoC) smart contract in Ethereum private blockchain using the Solidity programming language. The platform is validated in terms of time to execute functions in a data-sharing contract (DS-Contract) and hash-contract, the time to receive data packets from the gateway and the transaction time to run the smart contract. A low overhead is observed in the experiment which justifies the suitability of the platform to be used as a secure datasharing platform for SDWBAN.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Info & Comm Tech
Science, Environment, Engineering and Technology
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Engineering advancement over the last decade has significantly benefited the medical field, facilitating personalised and accessible healthcare. Various portable systems have been developed to obtain diagnostic parameters without the necessity for sedation or immobilisation of the patient, and even their presence at the medical facility. This can be especially important for populations that are at greater medical risk and are unable to undergo sedation, as well as for overall screening of the underlying conditions by continuous monitoring. This thesis provides engineering solutions aimed at improving the reliability of one of the modern medical diagnostic techniques – Wireless Capsule Endoscopy (WCE). It is a non-invasive approach for gastrointestinal (GI) tract examination that involves the natural propagation of a capsule through the entire tract of the patient while recording images of the lining. The video data are transmitted to a receiving unit outside the body, which is then accessed by medical practitioners for appropriate diagnostics. The Wireless Body Area Network (WBAN) technology describes the acquisition and transmission of the signal. One of the major challenges associated with WCE is the accurate localisation of the capsule due to the transit time being different for each individual. Localisation methods based on various physical principles are still under investigation by researchers. In this study, radiofrequency (RF) signal propagation analysis was used to provide accurate received signal strength (RSSI)-based localisation of the wireless endoscopy capsule. RSSI-based methods are widely used in indoor and outdoor positioning systems, allowing the estimation of the radial distance between reference sensors and an unknown transmitter position. Due to the significantly different electromagnetic (EM) properties of the human body as a propagation medium compared to air, one of the main objectives of this work was to develop an appropriate path loss propagation model. The advantage of the proposed solution is that it is based on an analytical approach and includes the attenuation constant defined by the EM properties of the soft tissues in the abdominal area. The theoretical basis of the developed attenuation path loss model (APLM) can be used to generalise and implement it for various In-to-On-Body communication systems at different operational frequencies. The APLM was numerically validated using CST Studio Software©, as well as by experiments on ex-vivo porcine tissues and in-vivo measurements on anesthetised living pigs. The experiments also served as the iii performance validation of a receiving inward cavity-backed slot antenna designed specifically for In-to-On-Body communications at 2.45 GHz, ISM band. In-vivo trials included implanting a wireless transmitter at several abdominal positions, which were then used for the 2-D and 3-D localisation accuracy assessment. Two trials were conducted separately at the medical facilities of The University of Southern Denmark (Odense, Denmark) and at the Herston Medical Research Centre, The University of Queensland (Brisbane, QLD, Australia). The research presents new knowledge for WBAN channel modelling for propagation media similar to the human body; confirms the reliability of the slot antenna performance for surface field measurements in WCE applications at 2.45 GHz; validates the application of the attenuation path loss model for In-to-On-Body communication channels; and it demonstrates high localisation accuracy when the proposed attenuation path loss model is used as an inverse solution for finding radial distances between the reference sensor and the unknown implant position.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Eng & Built Env
Science, Environment, Engineering and Technology
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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

The main focus of the work presented in this licentiate thesis concerns antenna design, adaptive antenna control and investigation on how the performance of small wireless nodes can be increased by inclusion of multiple antennas. 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 to achieve these goals. Two prototype systems have been developed where one has been used by National Defence Research Agency (FOI) to successfully monitor a test-subject moving in an outdoor terrain. The other prototype system shows the overall performance gain achievable in a wireless sensor node when multiple antennas and antenna beam steering is used. As an example of how to include multiple antennas in a wireless node the concept of using dual conformal patch antennas for wireless nodes is presented. The proposed antenna showed an excess of 10 dB gain when using a single driven antenna element as would be the case in a system utilizing antenna selection combining. When used as a 2-element phased array, up to 19 dB gain was obtained in a multiscattering environment. Using the second order resonance the proposed antenna structure achieves low mutual coupling and a reflection coefficient lower than -15 dB. The presented antenna design shows how a dual antenna wireless node can be designed using discrete phase control with passive matching which provides a good adaptive antenna solution usable for wireless sensor networks. The inclusion of discrete phase sweep diversity in a wireless node has been evaluated and shown to provide a significant diversity gain. The diversity gain of a discrete phase sweep diversity based system was measured in both a reverberation chamber and a real life office environment. The former environment showed between 5.5 to 10.3 dB diversity gain depending on the detector architecture and the latter showed a diversity gain ranging from 1 to 5.4 dB. Also the performance of nodes designed to be placed in a high temperature and multiscattering environment (the fan stage of a jet engine) has been evaluated. The work was carried out in order to verify that a wireless sensor network is able to operate in such a multiscattering environment. It was shown that the wireless nodes are able to operate in an emulated turbine environment based on real-life measured turbine fading data. The tested sensor network was able to transmit 32 byte packages using cyclic redundancy check at 2 Mbps at an engine speed of 13.000 rpm.
WISENET
WISEJET

Increasing number of ageing population and people who need continuous health monitoring and rising the costs of health care have triggered the concept of the novel wireless technology-driven human body monitoring. Human body monitoring can be performed using a network of small and intelligent wireless medical sensors which may be attached to the body surface or implanted into the tissues. It enables carers to predict, diagnose, and react to adverse events earlier than ever. The concept of Wireless Body Area Network (WBAN) was introduced to fully exploit the benefits of wireless technologies in telemedicine and m-health. The main focus of this research is the design and performance evaluation of strategies and architectures that would allow seamless and efficient interconnection of patient’s body area network and the stationary (e.g., hospital room or ward) wireless networks. I first introduce the architecture of a healthcare system which bridges WBANs and Wireless Local Area Networks (WLANs). I adopt IEEE 802.15.6 standard for the patient’s body network because it is specifically designed for WBANs. Since IEEE 802.15.6 has strict Quality of Service (QoS) and priorities to transfer the medical data to the medical server a QoS-enabled WLAN for the next hop is needed to preserve the end-to-end QoS. IEEE 802.11e standard is selected for the WLAN in the hospital room or ward because it provides prioritization for the stations in the network. I investigate in detail the requirements posed by different healthcare parameters and to analyze the performance of various alternative interconnection strategies, using the rigorous mathematical apparatus of Queuing Theory and Probabilistic Analysis; these results are independently validated through discrete event simulation models. This thesis has three main parts; performance evaluation and MAC parameters settings of IEEE 802.11e Enhanced Distributed Channel Access (EDCA), performance evaluation and tuning the MAC parameters of IEEE 802.15.6, and designing a seamless and efficient interconnection strategy which bridges IEEE 802.11e EDCA and IEEE 802.15.6 standards for a healthcare system.

L’amélioration de la qualité et de l’efficacité en santé est un réel enjeu sociétal. Elle implique la surveillance continue des paramètres vitaux ou de l’état mental du sujet. Les champs d’applications sont vastes : l’application la plus importante est la surveillance des patients à distance. Les avancées en micro-électronique, capteurs et réseaux sans-fil permettent aujourd’hui le développement de systèmes ambulatoires performants pour le monitoring de paramètres physiologiques, capables de prendre en compte d’importantes contraintes techniques : forte intégration pour la réduction de la taille et faible consommation pour une plus grande autonomie [1]. Cependant, la conception de ce type de réseaux de capteurs médicaux WBANs (Wireles Body Area Networks) se heurte à un certain nombre de difficultés techniques, provenant des contraintes imposées par les capacités réduites des capteurs individuels : basse puissance, énergie limitée et faible capacité de stockage. Ces difficultés requièrent des solutions différentes, encore très embryonnaires, selon l’application visée (monitoring à but médical). La forte mobilité et le changement rapide de la topologie du réseau dévoilent un verrou scientifique et social. En outre, l’interférence de différents capteurs constituant le WBAN augmente la difficulté de la mise en place de ce type de réseaux. De nombreuses solutions dans la littérature ont été étudiées, comme nous allons illustrer dans ce manuscrit, néanmoins elles restent limitées. Nous nous intéresserons tout particulièrement à la gestion des interférences Intra- et Inter-WBAN, leur impacte sur la fiabilité des transmissions (des liens) et la durée de vie de ce type de réseaux. Plus précisément, nous abordons ces problématiques en se basant sur des modélisations théoriques et analytiques et avec une conception pratique des solutions proposées. Afin d’atteindre les objectifs cités ci-dessous, nous abordons quatre solutions : • Une gestion des interférences intra-WBAN • Une gestion coopérative des interférences Inter-WBAN • Une gestion non coopérative des interférences, Inter-WBAN • Une gestion des interférences WBAN dans un contexte IoT Dans la première partie de cette thèse et afin de répondre en partie aux problèmes de gestion des interférences Intra-WBAN. Nous présentons deux mécanismes pour le WBAN : (a) CFTIM qui alloue dynamiquement des slots et des canaux dit- stables (avec un taux d’interférences le bas possible dans le temps) pour réduire les interférences intra-WBAN. (b) IAA ajuste dynamiquement la taille du superframe et limite le nombre de canaux à 2 pour abaisser les interférences Intra-WBAN et ainsi économiser l’énergie. Une validation avec un model probabiliste est proposé afin de valider théoriquement l’efficacité de notre solution. Les résultats de la simulation démontrent l’efficacité du CFTIM et de l’IAA en termes de réduction de la probabilité d’interférence, l’extension de la durée de vie du réseau et l’amélioration du débit et de la fiabilité des transmissions. Notre seconde contribution, propose une gestion coopératives des interférences Inter-WBAN en utilisant des codes orthogonaux. Motivé par un approvisionnement temporel distribué basé sur la norme [2] IEEE 802.15.6, nous proposons deux solutions. (a) DTRC qui fournit à chaque WBAN les connaissances sur les superframes qui se chevauchent. Le second, (b) OCAIM qui attribue des codes orthogonaux aux capteurs appartenant à deux listes de groupe de capteur en interférences de deux WBAN différents (SIL). Les résultats démontrent qu’OCAIM diminue les interférences, améliore le débit et préserve la ressources énergétiques. La troisième partie nous a permis d’aborder la gestion des interférences, mais cette fois ci d’une manière non-coopérative en se basant sur l’affectation couple Slot/Canal. Plus précisément, nous proposons deux schémas basés sur les carrés latins. (...)
A Wireless Body Area Network (WBAN) is a short-range network that consists of a coordinator (Crd) and a collection of low-power sensors that can be implanted in or attached to the human body. Basically, WBANs can provide real-time patient monitoring and serve in various applications such as ubiquitous health-care, consumer electronics, military, sports, etc. [1]. As the license-free 2.4 GHz ISM band is widely used among WBANs and across other wireless technologies, the fundamental problem is to mitigate the resulting co-channel interference. Other serious problems are to extend the network lifetime and to ensure reliable transmission within WBANs, which is an urgent requirement for health-care applications. Therefore, in this thesis, we conduct a systematic research on a few number of research problems related to radio co-channel interference, energy consumption, and network reliability. Specifically, we address the following problems ranging from theoretical modeling and analysis to practical protocol design: • Intra-WBAN interference mitigation and avoidance • Cooperative inter-WBAN interference mitigation and avoidance • Non-cooperative inter-WBAN interference mitigation and avoidance • Interference mitigation and avoidance in WBANs with IoT Firstly, to mitigate the intra-WBAN interference, we present two mechanisms for a WBAN. The first is called CSMA to Flexible TDMA combination for Interference Mitigation, namely, CFTIM, which dynamically allocates time-slots and stable channels to lower the intra-WBAN interference. The second is called Interference Avoidance Algorithm, namely IAA that dynamically adjusts the superframe length and limits the number of channels to 2 to lower the intra-WBAN interference and save energy. Theoretically, we derive a probabilistic model that proves the SINR outage probability is lowered. Simulation results demonstrate the effectiveness and the efficiency of CFTIM and IAA in terms of lowering the probability of interference, extending network lifetime, improving throughput and reliability. Secondly, we address the problem of interference among cooperative WBANs through using orthogonal codes. Motivated by distributed time provisioning supported in IEEE 802.15.6 standard [2], we propose two schemes. The first is called Distributed Time Correlation Reference, namely, DTRC that provides each WBAN with the knowledge about which superframes overlap with each other. The second is called Orthogonal Code Allocation Algorithm for Interference Mitigation, namely, OCAIM, that allocates orthogonal codes to interfering sensors belonging to sensor interference lists (SILs), which are generated based on the exchange of power-based information among WBANs. Mathematically, we derive the successful and collision probabilities of frames transmissions. Extensive simulations are conducted and the results demonstrate that OCAIM can diminish the interference, improve the throughput and save the power resource. Thirdly, we address the problem of co-channel interference among non-cooperative WBANs through time-slot and channel hopping. Specifically, we propose two schemes that are based on Latin rectangles. The first is called Distributed Algorithm for Interference mitigation using Latin rectangles, namely, DAIL that allocates a single channel to a timeslot combination to each sensor to diminish inter-WBAN interference and to yield better schedules of the medium access within each WBAN. The second is called Channel Hopping for Interference Mitigation, namely, CHIM, which generates a predictable interference free transmission schedule for all sensors within a WBAN. CHIM applies the channel switching only when a sensor experiences interference to save the power resource. Furthermore, we present an analytical model that derives bounds on collision probability and throughput for sensors transmissions. (...)

Abstract The value of wearable market is booming, especially in the healthcare application segment. This segment is driven by an increasing need for regular monitoring and early diagnosis of patients with growing prevalence of chronic diseases. Wireless communications worn in the close proximity of the body, the variety of applications, and their requirements set design considerations and challenges. In addition to the technical requirements, coexistence with adjacent wireless body area networks (WBANs) and other wireless systems need to be taken into account. A WBAN system needs to be highly reliable, low power, fast, and interference-immune. This thesis studies the performance of two different PHY layer implementations in interfered fading channels. The systems are the frequency modulated ultra wideband (FM-UWB), defined in the IEEE 802.15.6 standard, and narrowband SmartBAN physical layer. The performance of the systems was analyzed by using software simulators developed in Matlab. The author developed the SmartBAN simulator for the ETSI Technical Committee (TC) SmartBAN to study the performance of the new SmartBAN system. This is the first physical layer performance study of the SmartBAN system. In addition, the open literature does not offer similar results on the FM-UWB as presented in this thesis. Based on the results, it can be concluded that the FM-UWB is performing well in situations where high reliability and high interference tolerance is needed. In addition, the simplicity of the FM-UWB transceiver makes it more suitable than the direct sequence UWB (DS-UWB) for applications with data rates of hundreds of kbps. SmartBAN has the best performance in cases where more relaxed requirements for reliability and interference tolerance can be applied. Nevertheless, it became obvious that both systems need proper coexistence and interference mitigation mechanisms to ensure reliability in all scenarios
Tiivistelmä Puettavien laitteiden markkina-arvo on voimakkaassa kasvussa erityisesti terveydenhuollon sovellusalueella. Tämän sovellusalueen kiihdyttimenä toimii yhä suurempi tarve potilaiden kunnon jatkuvalle tarkkailulle sekä kroonisille taudeille alttiimpien potilaiden varhaiselle diagnosoinnille. Langattoman kehoverkon (WBAN) suunnittelun suurimpia haasteita ovat langaton tiedonsiirto kehon läheisyydessä, erilaiset sovellustyypit sekä niiden vaatimukset. Teknisten vaatimusten lisäksi on myös huomioitava rinnakkaiset kehoverkot sekä muut langattomat järjestelmät. Kehoverkkojärjestelmän on oltava todella luotettava, matalatehoinen, nopea ja häiriösietoinen. Väitöskirjassa tutkitaan kahta kehoverkon fyysisen kerroksen toteutusta häipyvissä ja häirityissä kanavissa. Nämä toteutukset ovat IEEE 802.15.6 -standardissa määritelty taajuusmoduloitu ultralaajakaista (FM-UWB) sekä kapeakaistainen SmartBAN. Järjestelmien suorituskykyä analysoitiin Matlab-ohjelmistosimulaattoreiden avulla. Työssä kehitettiin SmartBAN-simulaattori ETSI Technical Committee (TC) SmartBAN -työryhmälle järjestelmän suorityskykytutkimukseen. Tässä työssä esitetään SmartBAN-järjestelmän fyysisen kerroksen suorituskykytulokset, jotka ovat ensimmäiset laatuaan. Lisäksi kirjallisuudesta ei löydy vastaavia tuloksia FM-UWB:n osalta, kuten tässä työssä on esitetty. Tuloksien pohjalta voidaan päätellä, että FM-UWB suoriutuu hyvin tilanteissa, joissa vaaditaan suurta luotettavuutta sekä suurta häiriönsietokykyä. Lisäksi yksinkertainen lähetin-vastaanotinrakenne tekee siitä kiinnostavamman vaihtoehdon kuin suorahajotettu UWB (DS-UWB) sovelluksille, jotka vaativat satojen kbps:n tiedonsiirtonopeutta. SmartBAN toimii hyvin tilanteissa, joissa näistä vaatimuksista voidaan hieman joustaa. Kuitenkin on selvää, että molemmat järjestelmät tarvitsevat sopivan rinnakkais- ja häiriönvaimennustekniikan taatakseen luotettavuuden kaikissa tapauksissa

The rationale for a telemedicine system is the use of Information and Communications Technology (ICT) for the remote transmission of biomedical data and the remote control of biomedical equipment, in order to improve the provided health service. The integration of Wireless Body Area Networks (WBANs) in telemedicine systems does not only achieve significant improvements in the patient’s healthcare, but also enhances their quality of life. However, the potential benefits provided by these networks are limited by the energy constraints imposed when traditional batteries are used as the power source, since the replacement or recharging of these is not always an easy task. To that end, harvesting energy from the human environment can be a promising solution to the aforementioned problems. In this context, it is important to design efficient energy-aware medium access and resource management schemes to exploit the benefits of energy harvesting while guaranteeing the Quality of Service (QoS) in the network. This dissertation provides a contribution to the design and evaluation of novel solutions focused on energy-aware resource management for WBANs powered by human energy harvesting. In particular, our proposals are oriented to solve the problems caused by the differences in energy levels experienced by nodes due to their power supply by energy harvesting. The main thesis contributions are divided into two parts. The first part presents HEH-BMAC, an energy-aware hybrid-polling Medium Access Control (MAC) protocol for WBANs powered by human energy harvesting. HEH-BMAC is designed to provide medium access taking into account the capabilities of each node with respect to their energy profile. HEH-BMAC combines two types of access mechanisms, i.e., reserved polling access and probabilistic random access, in order to adapt the network operation to the types of human energy harvesting sources. The HEH-BMAC performance in terms of normalized throughput and energy efficiency is assessed by means of extensive computer-based simulations, revealing a good adaptation to potential changes in the energy harvesting rate, packet inter-arrival time and network size. HEH-BMAC has been proven to outperform IEEE 802.15.6 Standard for WBANs in terms of normalized throughput and energy efficiency, as the number of nodes increases under the same conditions of energy harvesting. The second part of the thesis is dedicated to the design and evaluation of PEH-QoS, a Power-QoS control scheme for body nodes powered by energy harvesting. PEH-QoS is designed to use efficiently the harvested energy and ensure that all transmitted packets are useful in a medical context, hence substantially improving the offered QoS. The obtained results show that this scheme efficiently manages the data queue, thus improving the node operation and optimizing the data transmission, and also provides QoS, while maintaining the node in energy neutral operation state.
1. Introducción La razón de ser de un sistema de telemedicina es utilizar las tecnologías de la información y la comunicación (TIC) para la trasmisión remota de datos médicos, y el control de dispositivos biomédicos a distancia, con el objetivo de mejorar el servicio de salud prestado. Con la integración de las redes inalámbricas de área corporal (WBANs, por sus siglas en ingles) en los sistemas de telemedicina, no solamente se podría mejorar significativamente el cuidado de la salud del paciente, sino que también se conseguiría mejorar su calidad de vida. Las WBANs están compuestas por dispositivos médicos destinados a aplicaciones clínicas. Dichos dispositivos son llamados nodos corporales. En la WBAN cada nodo desempeña una importante función relacionada con el tratamiento, diagnostico o monitoreo de la salud del paciente. Los nodos corporales deben ser capaces de realizar sus tareas eficientemente e interaccionar con el cuerpo humano de una forma cómoda e indetectable para el paciente. Para tal fin, dichos nodos deben ser pequeños y ligeros para poder colocarlos dentro o sobre el cuerpo humano. Dichas características están íntimamente relacionadas con el tamaño de la batería y el consumo energético del nodo. La energía de la batería no solamente restringe al nodo en peso y tamaño sino que también lo hace en su periodo de vida, puesto que se trata de una fuente finita. Los problemas impuestos por la dependencia energética a este tipo de fuente de poder limitan los beneficios potenciales de las WBANs. Además, cambiar o recargar la batería no siempre es factible, ya que esto podría poner en riesgo la vida del paciente o causar daños al mismo nodo. La más innovadora y prometedora técnica para solucionar los problemas relacionados a la energía de las baterías es la captación de energía del entorno humano. Usando captadores de energía, un BN podría aprovechar fenómenos físicos o químicos (ejemplo: calor, luz, movimiento, vibraciones, etc.) en el cuerpo humano para convertirlos en energía eléctrica. El proceso de captación de energía entrega pequeñas cantidades de energía y es dependiente de la clase, disponibilidad de la fuente y la localización del nodo en el cuerpo humano. La idea de una WBAN que trabaje en sinergia con el cuerpo humano es sumamente alentadora. Sin embargo, ciertas consideraciones deben ser tomadas en cuenta para mantener un nivel aceptable de calidad de servicio (QoS, por sus siglas en ingles) en una WBAN alimentada por captación de energía. Los requerimientos de QoS son más exigentes en las WBANs en comparación a las tradicionales redes de sensores inalámbricos (WSNs, por sus siglas en ingles). En WBAN, la QoS es una demanda fundamental por lo tanto la maximización del rendimiento, la reducción del retardo y la extensión de la vida de la red son algunos de los principales retos a alcanzar. En redes alimentadas por baterías, el principal propósito del control del acceso al medio (MAC) es el de prolongar la vida de la red. Por otra parte, en redes alimentadas por captación de energía el principal objetivo es maximizar el rendimiento utilizando la energía disponible. Mediante la captación de energía, se podría extender la vida de la red, pero otras métricas de QoS podrían ser degradadas (ejemplo: rendimiento, retardo, pérdida de paquetes de datos, etc.). Esta tesis ofrece una contribución al diseño y evaluación de novedosas soluciones enfocadas a la gestión de recursos, para WBANs alimentadas por captación de energía (HEH-WBANs, por sus siglas en ingles), de una forma energéticamente consciente. En particular, nuestras propuestas están orientadas a resolver los problemas causados por las diferencias en los niveles de energía que experimentan los nodos debido a sus fuentes de captación. Las principales contribuciones de esta tesis se dividen en dos partes. La primera parte presenta HEH-BMAC, un protocolo híbrido, energéticamente consciente, para el control del acceso al medio de los nodos en este tipo de WBANs. HEH-BMAC está diseñada para proporcionar acceso al medio teniendo en cuenta las capacidades de cada nodo con respecto a sus características energéticas. HEH-BMAC combina de forma dinámica dos tipos de mecanismos de acceso, acceso reservado (basado en identificación de usuario) y acceso aleatorio (basado en probabilidad de contención), con el fin de adaptar el funcionamiento de la red a los tipos de fuentes de captación de los nodos. El funcionamiento del protocolo HEH-BMAC, es evaluado a través de extensas simulaciones por ordenador utilizando las métricas de rendimiento normalizado y eficiencia energética. Los resultados obtenidos en estas pruebas, muestran que nuestro protocolo tiene una buena adaptación a cambios potenciales en las velocidades de captación de energía, frecuencia de arribo de los paquetes de datos, y en el tamaño de la red. La segunda parte de la tesis está dedicada al diseño y evaluación de PEH-QoS, un esquema de control de potencia y QoS para nodos corporales que estén alimentados por captación de energía. PEH-QoS está diseñado para el uso eficiente de la energía captada y asegurar que todos los paquetes de datos trasmitidos sean útiles en el contexto médico, por lo tanto mejorando sustancialmente la QoS ofertada. Los resultados obtenidos muestran que este esquema gestiona eficientemente la cola de datos, mejora la operación del nodo, optimiza la trasmisión de datos, y provee QoS, mientras mantienen al nodo en estado de operación neutral. 2. Objetivos La planificación, el desarrollo, y la realización de esta tesis doctoral persiguen el siguiente objetivo: Diseño y desarrollo de soluciones energéticamente eficientes y conscientes, destinadas a la gestión de recursos que garanticen los requisitos de calidad de servicio de las aplicaciones médicas en WBANs alimentadas por captación de energía en el entorno humano. Al lograr el objetivo antes mencionado, esta tesis constituirá una contribución al avance de la WBANs alimentadas por captación de energía en el entorno humano en términos de una gestión eficiente de su energía enfocada en mejor la calidad de servicio. Para afrontar con éxito el objetivo general, los siguientes objetivos específicos tuvieron que ser también cumplidos: 1. Proporcionar un una amplia revisión del estado del arte en las áreas de protocolos MAC para WBANs y en captación de la energía en el entorno humano. 2. Proponer y evaluar un protocolo MAC consciente de la energía, capaz de adaptar el funcionamiento de la red a la naturaleza aleatoria y variable en el tiempo de las fuentes de captación de energía en el entorno humano. 3. Diseñar y desarrollar un esquema de control que permita el uso óptimo de la escasa energía recogida por un nodo corporal alimentado por captación de energía en el cuerpo humano, con el fin de mejorar la calidad de servicio prestados. 4. Evaluar los resultados de nuestras propuestas y compararlos con sistemas estándares de referencia utilizando diferentes métricas de calidad de servicio. 3. Resultados a) HEH-BMAC: HYBRID POLLING MAC PROTOCOL FOR WIRELESS BODY NETWORKS OPERATED BY HUMAN ENERGY HARVESTING. Tomando en cuenta los últimos avances en las áreas de WBANs y en captación de energía, propusimos un protocolo MAC hibrido al cual llamamos HEH-BMAC. HEH-BMAC es un protocolo de acceso al medio, el primero dentro de nuestro conocimiento, diseñado para WBANs alimentadas por captación de energía del entorno humano. La principal característica de HEH-BMAC es que es un protocolo energéticamente consciente en condiciones de captación de energía, ya que el funcionamiento de cada nodo es adaptado dinámicamente dependiendo de su nivel de energía. En particular nuestro protocolo tiene las siguientes características: i) Este ofrece dos niveles de prioridades a través de la combinación de dos mecanismos diferentes de acceso al medio. El primer mecanismo de acceso es el de identificación de usuario (ID-POLLING) para acceso reservado, dicho mecanismo está pensado para nodos con captación de energía predecible (por ejemplo: Generadores piezoeléctricos que aprovechan los latidos del corazón o de los movimientos respiratorios) o nodos con alta prioridad (por ejemplo: Electrocardiógrafo, electroencefalógrafo, etc.). El segundo método de acceso es por probabilidad de contención (PC-ACCESS) para acceso aleatorio, este mecanismo está destinado para nodos alimentados con fuentes de captación de energía no predecible (por ejemplo: generadores termoeléctricos sobre la piel, generadores piezoeléctricos que aprovechan la locomoción humana, etc.) o nodos con prioridad normal (por ejemplo: termómetros, flujo sanguíneo, etc.). ii) Los periodos de tiempo para los accesos al medio, ya sea ID-POLLING o PC-ACCESS, son ajustados dinámicamente de acuerdo a los niveles energéticos de los nodos. Dicha asignación es realizada a través de un algoritmo ejecutado en el nodo corporal coordinador de la red (BNC). El BNC ejecuta el algoritmo DYNAMIC SCHEDULE ALGORITHM, pudiendo de esta forma manejar la comunicación de todos los nodos que forman la WBAN. Dicho algoritmo contrala de manera conjunta ambos tipos de acceso a través de una lista dinámica para los nodos en ID-POLLING y a través de un algoritmo de actualización del valor de umbral para la contención en los nodos en PC-Access. Los nodos en ID-POLLING acceden al medio de forma expedita y los nodos en PC-Access tienen un acceso probabilístico. iii) Al ejecutarse el acceso al medio de forma dinámica, HEH-BMAC permite la adición y remoción de nodos en la WBAN, puesto que la actualización de la lista dinámica y del algoritmo de actualización del valor umbral de contención son ajustados dependiendo de la respuesta de la cantidad de nodos que están funcionando en la red. RESULTADOS 1: Primeramente brindamos un comprensivo estado del arte, además expusimos nuestros criterios de diseño y explicamos detalladamente cómo funciona nuestra propuesta. Las pruebas realizadas a nuestro protocolo MAC fueron simuladas (a través de un simulador que desarrollamos en MATLAB) con diferentes velocidades de captación de energía. Las métricas utilizadas para la evaluación de nuestra propuesta fueron eficiencia energética y rendimiento normalizado. Como resultado de este estudio pudimos comprobar la buena adaptación que posee HEH-BMAC a diferentes condiciones energéticas, tiempos de arribo de datos y flexibilidad al agregar o remover nodos en la red. Las pruebas las realizamos con cuatro diferentes velocidades de trasmisión de datos. Como resultado de esta investigación, realizamos el trabajo: E. Ibarra, A. Antonopoulos, E. Kartsakli and C. Verikoukis., “HEH-BMAC: Hybrid Polling MAC Protocol for Wireless Body Area Networks Operated by Human Energy Harvesting”. Journal of Telecommunication Systems, Modeling, Analysis, Design and Management. Special Issue on: Research Advances in Energy Efficient MAC protocols for WBANs. (Accepted, December 2012). El siguiente paso en nuestro proceso investigativo fue comparar el desempeño de nuestro protocolo HEH-BMAC con el recién publicado (29 de febrero de 2012) protocolo IEEE 802.15.6 es el protocolo de red para redes de sensores corporales del IEEE diseñado para comunicación dentro y fuera del cuerpo humano. Tomando en cuenta que el protocolo de la IEEE 802.15.6. no fue diseñado para trabajar en redes WBANs alimentadas por captación de energía, escogimos un escenario en que ambos protocolos tuvieran suficiente energía para trabajar correctamente. Comparamos dos configuraciones del protocolo acceso CSMA/CA del IEEE con nuestra propuesta HEH-BMAC. La comparación entre ambos protocolos se realizó a través de las métricas rendimiento normalizado y eficiencia energética. RESULTADOS 2: Como resultado de este trabajo comprobamos que nuestro protocolo HEH-BMAC tiene mejor rendimiento normalizado y comportamiento que el del IEEE 802.15.6 en condiciones de captación de energía. Además, nuestro protocolo tiene un nivel alto de eficiencia energética (ver figura 1) cuando se aumentan el número de nodos a la WBANs, en comparación al protocolo de la IEEE 802.15.6. Como resultado de esta investigación, realizamos el trabajo: E. Ibarra, A. Antonopoulos, E. Kartsakli and C. Verikoukis, “Energy Harvesting Aware Hybrid MAC Protocol for WBANs”, IEEE HEALTHCOM 2013, October 2013, Lisbon, Portugal. b) JOINT POWER-QoS CONTROL SCHEME FOR ENERGY HARVESTING BODY SENSOR NODES En este trabajo desarrollamos un esquema de control para los BNs alimentados por captación de energía con el fin de mejorar la calidad de servicio (QoS) prestada por cada nodo. Dicho esquema lo hemos llamado esquema de control PEH-QoS. PEH-QoS está formado por tres sub-módulos que interaccionan entre sí con el objetivo de conseguir el mejor QoS posible. Los sub-módulos que componen dicho esquema son: i. PHAM: POWER-EH AWARE MANAGEMENT SUB-MODULE: El objetivo del mismo es realizar un uso óptimo de la escasa energía recabada. Solo realizando las funciones de detección o de trasmisión cuando se tenga la cantidad suficiente de energía para completar los procesos. Controlando el consumo energético del BN para mantenerlo en un estado de Operación Energéticamente Neutral (Estado ENO). El estado ENO, es definido como una condición en que el nodo gasta menos o igual cantidad de energía que la recolectada del ambiente, manteniendo un rendimiento deseado. ii. DQAC: DATA QUEUE AWARE CONTROL SUB-MODULE: El objetivo de este sub-modulo es de estabilizar la cola de datos en condiciones de captación de energía. El principal función de DQAC es evitar la saturación de la cola de datos y mantener la validez clínica de la información almacenada por medio de la eliminación de paquetes que han perdido relevancia y actualizando la cola de datos. iii. PASS: PACKET AGGREGATOR/SCHEDULING SYSTEM SUB-MODULE: La función de este sub-modulo es la de optimizar cada trasmisión realizada, enviando en cada proceso de comunicación la mayor cantidad de paquetes posibles. Esto se realiza a través de un sistema de agregación de paquetes dependiendo de la energía disponible (PHAM) y del estado de la cola de datos (DQAC). RESULTADOS 3: Comparamos un BN aplicándole nuestra propuesta, con el mismo nodo sin PEH-QoS. Ambos fueron comparados en las mismas condiciones de captación de energía. Como resultado de dicho estudio obtuvimos que nuestro sistema supero sustancialmente al nodo de referencia en cuanto a rendimiento normalizado, eficiencia energética, perdida de paquetes de datos, y retardo promedio end-to-end. Además, gracias a PEH-QoS alcanzo niveles altos de eficiencia en la detección de eventos y en la eficiencia de almacenaje de datos. Como resultado de esta investigación, realizamos el trabajo: E. Ibarra, A. Antonopoulos, E. Kartsakli and C. Verikoukis, “Joint Power-QoS Control Scheme for Energy Harvesting Body Sensor Nodes”, IEEE ICC 2014, June 2014, Sydney, Australia. 4. Discusiones y Conclusiones HEH-BMAC asigna períodos de tiempo, tanto para ID-POLLING y el PC- ACCESS a través del DYNAMIC SCHEDULE ALGORITHM. La distribución del tiempo se llevan a cabo de una manera dinámica, logrando el uso óptimo del medio. Todos los nodos del WBAN son energéticamente conscientes, es decir, tratan de acceder al medio sólo si tienen los paquetes de datos a transmitir y si tienen suficiente energía para terminar con éxito una secuencia de transmisión. La combinación de estos dos modos de acceso y el DYNAMIC SCHEDULE ALGORITHM, no sólo mejora el rendimiento normalizado y la eficiencia de energía del sistema, sino que también permite la adaptación de la red a los cambios en el número de nodos, el tiempo entre llegadas de datos y la tasa en que se capta energía del ambiente. Por último, para completar nuestro estudio de investigación acerca de HEH-BMAC, se comparó el rendimiento normalizado y la eficiencia energética de nuestro protocolo con el protocolo estándar IEEE 802.15.6. En comparación con el estándar IEEE 802.15.6, HEH-BMAC logra una ganancia de hasta un 20% en la eficiencia de energía y hasta un 56% en el rendimiento normalizado. Además, los resultados mostraron que nuestro protocolo puede adaptarse mejor a un aumento potencial en el número de nodos en la red, en comparación con el estándar en las mismas condiciones de captación de energía. El proceso de captación de energía introduce variaciones en los niveles de energía de los BNs (debido principalmente a las características y la disponibilidad de las fuentes que se captarán) que afectan directamente a su funcionamiento, reduciendo su rendimiento y la eficiencia de las tareas realizadas. Pequeñas cantidades de energía que pueden ser captadas del cuerpo humano deben utilizarse de una manera óptima y eficiente para evitar que se desperdicie. PEH-QoS aborda de manera eficiente estos problemas con el fin de mejorar la calidad de servicio proporcionadas. Los resultados obtenidos mostraron que cuando se aplica PEH-QoS, la eficiencia de energía del nodo se incrementa de 0,78 MB / J hasta 39,6 MB / J (≈ 50 veces), mientras la pérdida de paquetes se reduce hasta 0,39% y el promedio de retardo hasta 130 ms. Nuestro enfoque mejora sustancialmente la calidad de servicio prestado, mientras que también logra una mayor eficiencia de detección y de almacenamiento de datos, lo que demuestra que las técnicas basadas en la conciencia de la energía son excelentes herramientas para mejorar el rendimiento de la BN. En conclusión, los dos esquemas propuestos, HEH-BMAC y PEH QoS, han introducido importantes mejoras en el rendimiento del sistema, tanto a nivel de las HEH-WBANs y como de los BNs.

Le réseau Body Area Network (WBAN) est un réseau de capteurs placés sur le corps ou à l'intérieur du corps, communiquant sans fil entre eux ou avec un terminal mobile placé à l'extérieur du corps. De nombreuses applications sont envisageables pour le WBAN allant du domaine médical (implants, monitoring…), au domaine sportif en passant par les loisirs. Une des configurations envisagées est On-Body, où deux ou plusieurs capteurs sont placés sur le corps. Le travail mené dans le cadre de cette thèse consiste à caractériser le canal de propagation dans un environnement WBAN à 900MHz et à 2,4GHz. Dans ce but, les interactions antenne/ corps ont été traitées dans un premier temps par simulations sur des fantômes numériques afin d'analyser l'effet du corps sur l'antenne. Ensuite, dans un deuxième temps plusieurs simulations et mesures sur des personnes volontaires ont été réalisées afin de modéliser les pertes sur le corps humain pour plusieurs scénarios, l'influence de la morphologie a été soulignée et un modèle statistique basé sur les mesures a été déduit. Une analyse des paramètres liés à la propagation comme les étalements de retards et le SAR ont été calculés. Enfin, nous avons présenté la méthode du retournement temporel qui repose sur la focalisation spatio-temporelle d'une onde sur une cible à partir de la connaissance de la réponse impulsionnelle du milieu de propagation. Les premiers résultats de son application dans le contexte WBAN ont montré des limites à cause des fortes pertes des tissus du corps humain.

Nowadays, each user or organization is already connected to a large number of sensor nodes which generate a substantial amount of data, making their management not an obvious issue. In addition, these data can be confidential. For these reasons, developing a secure system managing the data from heterogeneous sensor nodes is a real need. In the first part, we developed a composite-based middleware for wireless sensor networks to communicate with the physical sensors for storing, processing, indexing, analyzing and generating alerts on those sensors data. Each composite is connected to a physical node or used to aggregate data from different composites. Each physical node communicating with the middleware is setup as a composite. The middleware has been used in the context of the European project Mobesens in order to manage data from a sensor network for monitoring water quality. In the second part of the thesis, we proposed a new hybrid authentication and key establishment scheme between senor nodes (SN), gateways (MN) and the middleware (SS). It is based on two protocols. The first protocol intent is the mutual authentication between SS and MN, on providing an asymmetric pair of keys for MN, and on establishing a pairwise key between them. The second protocol aims at authenticating them, and establishing a group key and pairwise keys between SN and the two others. The middleware has been generalized in the third part in order to provide a private space for multi-organization or -user to manage his sensors data using cloud computing. Next, we expanded the composite with gadgets to share securely sensor data in order to provide a secure social sensor network

Dans le cadre de cette thèse, on se proposait de développer de nouveaux mécanismes de radiolocalisation, permettant de positionner les nœuds de réseaux corporels sans-fil (WBAN) mobiles, en exploitant de manière opportuniste des liens radio coopératifs bas débit à l'échelle d'un même corps (i.e. coopération intra-WBAN), entre réseaux distincts (i.e. coopération inter-WBAN), et/ou vis-à-vis de l'infrastructure environnante. Ces nouvelles fonctions coopératives présentent un intérêt pour des applications telles que la navigation de groupe ou la capture de mouvement à large échelle. Ce sujet d'étude, par essence multidisciplinaire, a permis d'aborder des questions de recherche variées, humine-biomécanique et de ayant trait à la modélisation physique (e.g. modélisation spatio-temporelle des métriques de radiolocalisation en situation de mobilité, modélisation de la mobilité groupe...), au développement d'algorithmes adaptés aux observables disponibles (e.g. algorithmes de positionnement coopératifs et distribués, sélection et ordonnancement des liens/mesures entre les nœuds...), aux mécanismes d'accès et de mise en réseau (i.e. en support aux mesures coopératives et au positionnement itératif). Les bénéfices et les limites de certaines de ces fonctions ont été en partie éprouvés expérimentalement, au moyen de plateformes radio réelles. Les différents développements réalisés tenaient compte, autant que possible, des contraintes liées aux standards de communication WBAN émergeants (e.g. Impulse Radio - Ultra Wideband (IR-UWB) IEEE 802.15.6), par exemple en termes de bande fréquentielle ou de taux d'erreur.

Le déploiement de biocapteurs sur le corps humain, en vue de la collecte des données physiologiques constitue ce qui est appelé un réseau de capteurs corporel sans fil ou Wireless Body Area Network (WBAN). Ainsi, pour assurer les communications entre les diffèrent composants des WBANs, l’organisme IEEE a établi la norme IEEE 802.15.6, comme norme de communication optimisée pour les terminaux et capteurs exigeants de faible consommation énergétique et fonctionnants dans ou autour du corps humain (mais non limitée aux humains). Dans ce contexte, plusieurs études de simulation ont été menées dans la littérature pour analyser et évaluer les performances du protocole d’accès CSMA/CA de la norme IEEE 802.15.6. De plus, des efforts ont été faits en matière de modélisation de ce protocole afin de mieux analyser les caractéristiques de la norme dans un contexte plus général. Cependant, ces modèles sont partiellement applicables aux applications WBANs qui présentent des trafics réseaux hétérogènes.Cette thèse porte sur la modélisation de la norme IEEE 802.15.6 dans le but de fournir un moyen d’évaluation et d’analyse de cette norme dans divers conditions et situations. Nous avons essayé, à travers les principales contributions réalisées dans le cadre de cette thèse de combler les lacunes des travaux existants comme suit : la première contribution concerne une évaluation des performances de la norme IEEE 802.15.6 utilisant de nombreuses stratégies de gestion des files d’attentes, dans un cadre médical réaliste (surveillance à domicile d'un patient souffrant d’un problème cardiaque). La deuxième contribution propose un modèle de gestion de file d’attente LLQ (Low Latency Queuing) comme complément au protocole CSMA/CA afin de répondre efficacement aux exigences du standard en termes de la Qualité de Service (QoS) pour certains types d’applications.La troisième contribution porte sur la proposition d’un modèle analytique permettant l'étude des performances du protocole d'accès CSMA/CA de la norme IEEE 802.15.6, en termes de latence et du taux de délivrance des paquets, sous l’hypothèse que les WBANs sont composés de nœuds hétérogènes qui génèrent un trafic hétérogène en termes de priorité.La dernière contribution traite la problématique de sécurité dans les réseaux WBANs. Elle propose un protocole de sécurité appelé "Server-Based Secure Key Management for the IEEE 802.15.6 standard" (SBSKM) qui permet au standard de pallier à la vulnérabilité d’usurpation d’identité, par l’inclusion d’un serveur de confiance, responsable de la création, de l'initialisation et de la distribution des clés de chiffrement et de leur renouvellement, ainsi que de garantir l'identité des capteurs qui se joignent au réseau.Mots-clés: réseaux de capteurs corporels (WBANs), IEEE 802.15.6, processus de renouvèlement et de récompense, files d’attente avec priorité, attaques d’usurpation d’identité
The deployment of several biosensors on the human body for the collection of physiological data forms what is called a Wireless Body Area Network (WBAN). Thus, to ensure wireless communications between the different components of WBANs, the IEEE has established the IEEE 802.15.6 standard, which is an optimized communication standard for low-power devices that operate on, in, or around the human body (but not limited to humans). In this context, several simulation studies have been conducted in the literature to analyze and evaluate the performance of the IEEE 802.15.6 CSMA/CA access scheme. Also, efforts have been made to model this scheme to better analyze the characteristics of the standard in a more general context. However, these models are partially applicable to WBANs applications with heterogeneous network traffic.This thesis deals mainly with a challenge related to the modeling of the IEEE 802.15.6 standard to provide a tool for evaluation and analysis of this standard in various channel conditions and situations. We have tried, through the main contributions made in this thesis, to address the shortcomings noted in existing work as follows: the first contribution concerns an evaluation of the performance of the IEEE 802.15.6 standard using numerous queue management strategies, in a realistic medical setting (home monitoring of a patient with a heart problem). The second contribution proposes an LLQ (Low Latency Queuing) queue management model as a complement to the CSMA/CA protocol to efficiently meet the requirements of the standard in terms of Quality of Service (QoS) for certain types of applications.The third contribution deals with the proposal of an analytical model allowing the study of the CSMA/CA access scheme of the IEEE 802.15.6 standard, in terms of latency and packet delivery rate under the assumption that WBANs are composed of heterogeneous nodes and that each of them generates heterogeneous traffic in terms of priority.The last contribution proposes a security protocol called "Server-Based Secure Key Management for the IEEE 802.15.6 standard" (SBSKM) that allows the standard to address the vulnerability of impersonation attacks, by including a trusted server, responsible for the creation, initialization, and distribution of encryption keys and their renewal, as well as to guarantee the identity of sensors joining the network.Keywords: Body Area Networks (WBANs), IEEE 802.15.6 standard, renewal reward process, priority queues, and impersonation attacks

This document will provide a detailed description of the original design behind our device, device casing, and iOS application. It will cover process of assembly, as well as failure analysis and future directions for the project.

Negli ultimi dieci anni si è rinnovata l’esigenza di sviluppare nuove tecnologie legate alla telemedicina, specie a seguito dello sviluppo dei sistemi di telecomunicazione che consentono ad ogni persona di avere a disposizione sistemi portatili, come gli smartphone, sempre connessi e pronti a comunicare. Lo stesso sviluppo si è avuto all’interno dei sistemi sanitari in cui è diventato fondamentale informatizzare le attività ospedaliere per via del contesto demografico a cui si va incontro: invecchiamento della popolazione e aumento del numero di pazienti affetti da malattie croniche. Tutti questi aspetti portano all’attuazione di un cambiamento strategico. Le Body Area Network, fulcro di questo lavoro di tesi, rappresentano la risposta a questa necessità. Si spiegano l'architettura e le tecnologie abilitanti per la realizzazione di queste reti di sensori, gli standard di comunicazione tramite i quali avviene la trasmissione dei dati e come le reti si interfacciano con i pazienti e le strutture sanitarie. Si conclude con una panoramica sui sensori di una BAN e alcuni esempi in commercio.

ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NV
This paper describes a project to implement a body area network to monitor the movements of a human subject. The sensor nodes can measure six degrees of movement by using a three axis accelerometer and three axis gyroscope. The data is transmitted wirelessly from the sensors to a wearable microcontroller. The microcontroller interfaces with a computer application that allows a user to easily analyze and interpret the stored data.

The master thesis is a prototyping project of a wireless body area network (WBANs) for patient monitoring in hospitals. The goal of this project was to study various technologies suitable for wireless body area networks, complete a requirement analysis, design a WBAN suitable to achieve the requirements and to test and evaluate the system against the requirements. Seven sensor end nodes are chosen to monitor seven vital signs for patient monitoring. After studying different technologies suitable for WBANs, IEEE 802.15.4j was chosen because it communicates in a special allocation of medical spectrum of 2360 to 2400MHz. A coordinator or master will be the center of the network using a star topology. Due to certain limitations in the firmware of the NXP FRDMKW40Z, IEEE 802.15.4j had to be dropped and IEEE 802.15.4 was the final chosen technology because the only difference between IEEE 802.15.4j and IEEE802.15.4 is the difference in the physical layer, while the developed application remains the same, making the shift back to IEEE802.15.4j, in the future, simple. There have been several projects working on the same idea with IEEE 802.15.4, but they do not combine multiple sensors to form a network and the total throughput requirements for this thesis project are much higher. The beacon mode and the non-beacon mode of IEEE 802.15.4 are studied. Non beacon mode is unpredictable due to the use of carrier sense multiple access with collision avoidance (CSMA/CA) to access the medium. When multiple end nodes compete to get access to the medium, unreliability is introduced into the system. In the beacon mode, because of the slotted CSMA access of sixteen equally spaced time slots for communication, there is a restriction of the size of a time slot and thus, the high throughput requirement of the system is not met. The solution proposed in the thesis project is to develop a custom time slot system in the non-beacon mode, where each end node is granted a reserved time slot of a specific length as required by the end node. There is a timer mechanism which makes sure that the time slots for each device maintain the time limit on the time slot, on the side of the main master/coordinator of the network and on the side of the end node. The protocol for an end node to join a personal area network (PAN) is called as the association process. The association process enables the end node to be a part of a PAN to exchange its sensor data. Traditionally, in IEEE 802.15.4, the end nodes scan the sixteen IEEE 802.15.4 channels and when an appropriate coordinator is found, the end node initiates the association process with the coordinator. The solution proposed for the formation of the network by the association process is to use two different technologies. The end nodes and the coordinator exchange information using near field communication (NFC) technology by a simple tapping mechanism. The end node has an active NFC tag while the coordinator has an NFC reader. During the tap between the two devices, first the coordinator reads the end node data from the active tag. This data is required to form the custom time slot. Next the coordinator writes all association information into the active tag. After the NFC data exchange is done, the end node initiates the traditional IEEE 802.15.4 association protocol to join the coordinator’s PAN. Similarly after seven end nodes are associated to the coordinator, the network begins to function. All the end nodes communicate their data to the coordinator. The coordinator collects all the sensor data from the seven end nodes and may send the cumulative sensor data to the backend database servers which may be viewed by the medical authorities, this part is not included in the current version of the project. Several tests are run on this system to evaluate the requirements of latency, throughput and quality of service with two different ranges of 20cm and 250cm. The latency of association between the coordinator and end node is 632ms. The required throughput is met by the network. The packet delivery rate of the system is always above 99%. The graphs for packet delivery rates for all the sensors with a range of 20cm and 250 cm are shown in the appendices. The probabilities for the packet delivery rates greater than 90%, 99%, 99.9% and 99.99% are also graphically shown using a normal distribution in the appendices.

Implanted Devices are important components of the Wireless Body Area Network (WBAN) as a promising technology in biotelemetry, e-health care and hyperthermia applications. The design of WBAN faces many challenges, such as frequency band selection, channel modeling, antenna design, physical layer (PHY) protocol design, medium access control (MAC) protocol design and power source. This research focuses on the design of implanted antennas, channel modeling between implanted devices and Wireless Power Transfer (WPT) for implanted devices. An implanted antenna needs to be small while it maintains Specific Absorption Rate (SAR) and is able to cope with the detuning effect due to the electrical properties of human body tissues. Most of the proposed antennas for implanted applications are electric field antennas, which have a high near-zone electric field and, therefore, a high SAR and are sensitive to the detuning effect. This work is devoted to designing a miniaturized magnetic field antenna to overcome the above limitations. The proposed Electrically Coupled Loop Antenna (ECLA) has a low electric field in the near-zone and, therefore, has a small SAR and is less sensitive to the detuning effect. The performance of ECLA, channel model between implanted devices using Path Loss (PL) and WPT for implanted devices are studied inside different human body models using simulation software and validated using experimental work. The study is done at different frequency bands: Medical Implanted Communication Services (MICS) band, Industrial Scientific and Medical (ISM) band and 3.5 GHz band using ECLA. It was found that the proposed ECLA has a better performance compared to the previous designs of implanted antennas. Based on our study, the MICS band has the best propagation channel inside the human body model among the allowed frequency bands. The maximum PL inside the human body between an implanted antenna and a base station on the surface is about 90 dB. WPT for implanted devices has been investigated as well, and it has been shown that for a device located at 2 cm inside the human body with an antenna radius of 1 cm an efficiency of 63% can be achieved using the proposed ECLA.
Ph. D.

Wireless body area networks (WBANs) are one of the key technologies that support the development of ubiquitous health monitoring, which has attracted increasing attention in recent years. Wireless on-body sensors free the patients from countless tangled wires, and wireless implanted sensors make it possible for the doctors to monitor an extensive range of critical bio-information continuously, which is crucial for a quick reaction when emergency happens. Due to the size limitation on the sensor nodes and the importance of the life signals transmitted, compared with general wireless sensor networks (WSNs), WBANs have more stringent requirements on reliability and energy efficiency during data's collection and transmission. This thesis aims to propose effective network designs to increase packet delivery rate, reduce energy consumption and prolong network lifetime for WBANs. In order to solve the major challenges faced by WBANs, due to the energy efficiency and reliable data transmission requirements, in this thesis, network design over multiple layers are considered, including physical layer, medium access control (MAC) layer and routing layer. Network topology design that is suitable for WBANs is also considered. Specifically this thesis: 1. Investigates the design of MAC protocols and proposes an opportunistic scheduling scheme by applying heuristic scheduling and dynamic superframe length adjustment to improve the packet delivery rate and improve transmission reliability; 2. Formulates and solves a mathematical optimization problem to maximize network lifetime, which jointly considers network topology design, transmission power control and routing strategy. Multilevel primal and dual decomposition methods are employed to solve the proposed non-convex mixed-integer optimization problem. A solution with fast convergence rate based on binary search is provided. Simulations have been conducted to show that our proposed network design increases network performance to a large extent compared with existing solutions.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate

Deploying wireless body area networks (WBANs) in the long-term at-home monitoring of a patient’s physiological and bio-kinetic conditions has become increasingly prevalent. However, such WBANs do not typically incorporate mechanisms to detect and correct for the possibility of accidentally switching up wearable wireless sensor nodes (W²SNs), where a node assigned to one limb is placed on another, and vice-versa, leading to possible incorrect prognoses from interpreting the data. In this thesis, we present a new scheme to automatically identify and verify the locations of W²SNs in a WBAN. Using small-scale geospatial information, instantaneous atmospheric air pressures at each node are examined and compared to map and match them in physical space. By enhancing the context-awareness of WBANs, this enhancement enables unassisted sensor node placement, providing a practical solution to obtain and continuously monitor node locations at a sufficient resolution to recognize limb placement, without multidimensional fine-grain position information. Only a single atmospheric air pressure sensor (A²PS) is added to each W²SN; compared to existing localization techniques, no beacons or extra nodes are required, enabling an inexpensive and self-contained solution. To quantify and validate the accuracy, consistency and reliability of this localization scheme, a statistical analysis on a set of commercially-available air pressure sensors and an experimental prototype WBAN is conducted to examine the scheme’s performance and limitations. This study has verified that this approach is indeed capable of distinguishing between positions indicative of expected separation between different limbs of the patient’s body. Based on a 60cm separation between nodes, the statistical analysis consistently exceeded 95% accuracy within the confidence interval (CI), demonstrating great promise for incorporation into commercial WBANs. We also present and experimentally demonstrate an enhancement aiming to reduce false-positive (Type I) errors in conventional accelerometer-based on-body fall detection schemes. Our statistical analysis has shown that by continuously monitoring the patient’s limb positions, the W²SN position information would enable the WBAN to better classify ‘fall-like’ motion from actual falls, where the patient requires remote caregiver assistance.

Wireless body area network (WBAN) has emerged in recent years as a special class of wireless sensor network; hence, WBAN inherits the wireless sensor network challenges of interference by passive objects in indoor environments. However, attaching wireless nodes to a person’s body imposes a unique challenge, presented by continuous changes in the working environment, due to the normal activities of the monitored personnel. Basic activities, like sitting on a metallic chair or standing near a metallic door, drastically change the antenna behaviour when the metallic object is within the antenna near field. Although antenna coupling with the human body has been investigated by many recent studies, the coupling of the WBAN node antenna with other objects within the surrounding environment has not been thoroughly studied. To address the problems above, the thesis investigates the state-of-the art of WBAN, eximanes the influence of metallic object near an antenna through experimental studies and proposes antenna design and their applications for near field environments. This thesis philosophy for the previously mentioned challenge is to examine and improve the WBAN interaction with its surrounding by enabling the WBAN node to detect nearby objects based solely on change in antenna measurements. The thesis studies the interference caused by passive objects on WBAN node antenna and extracts relevant features to sense the object presence within the near field, and proposes new design of WBAN antenna suitable for this purpose. The major contributions of this study can be summarised as follows. First, it observes and defines the changes in the return loss of a narrow band antenna when a metallic object is introduced in its near field. Two methods were proposed to detect the object, based on the refelction coefficient and transmission coefficient of an antenna in free space. Then, the thesis introduces a new antenna design that conforms to the WBAN requirements of size, while achieving very low sensitivity to human body. This was achieved through combining two opposite Vivaldi shapes on one PCB and using a metallic sheet to act as a reflector, which minimised the antenna coupling with the human body and reduced the radiation pattern towards the body. Finally, the proposed antennas were tested on several human body parts with nearby metallic objects, to compare the change in antenna s-parameters due to presence of the human body and presence of the metallic object. Based on the measurements, basic statistical indicators and Principal Component Analysis were proposed to detect object presense and estimate its distance. In conclusion, the thesis successfully shows WBAN antenna’s ability to detect nearby metallic objects through a set of proposed indicators and novel antenna design. The thesis is wrapped up by the suggestion to investigate time domain features and modulated signal for future work in WBAN near field sensing.

A wireless body area network (WBAN) is a collection of miniaturized and energy efficient wireless sensor nodes which monitor human body functions and its surroundings. It has been observed that WBANs perform single application per network, computation and storage capacities are scarce and there is no or limited mobility support. Technically complex WBAN application solutions today, find refuge in processing computationally complex data external to WBANs, i.e., processing sensor data on a conventional PC which is impractical and clumsy. There is a strong need for WBAN platforms which can perform computationally complex tasks on their own having enough resources in terms of computation and memory but still consuming as low power as possible in order to prolong network uptime. In this thesis work, an improved WBAN named multipurpose-BodyNet (MPBodyNet) is implemented. It has enough computational and memory resources and compact software solutions to achieve high performance and fidelity. MPBodyNet is a self-configuring, multipurpose WBAN which can perform multiple applications and user can switch between applications by a mere push of button. It supports mobility and it acts like an agent network to other networks. MP-BodyNet forms a hierarchy where low-capability networks are supported by higher-capacity networks. Hardware used for MP-BodyNet has been designed by WSN-Team at Centre for Wireless Communications, University of Oulu and this thesis proposes two application scenarios. Senior citizen protection mode (SPM) deals with a very hot health care issue for elderly people and patients. An algorithm is proposed and implemented that can detect falls or if the subject/patient has fainted. In SPM, MP-BodyNet can generate alarms in case of emergency and events can be seen on a central server as well as a special alarm is generated to the user’s phone (android app.) which can in turn establish an emergency call automatically. Algorithmic efficiency achieved is 100%. Silent communication mode (SCM) deals with a military hand signal/gesture recognition application. A quite complex pattern recognition algorithm has been proposed with two novelties in it i.e., a sampling process is introduced in the algorithm and the whole algorithmic processing is supposed to be done on the sensor node itself, no processing is supposed to be happening external to the WBAN. Algorithm for SCM is only presented here conceptually after rigorous research about the subject at disposal. It is not implemented in this thesis due to lack of time and is saved for future development. After a gesture would be recognized, an audio message mapped to the gesture will be heard over a headphone.

Abstract. The last decade has been really ambitious in new research and development techniques to reduce energy consumption especially in wireless sensor networks (WSNs). Sensor nodes are usually battery-powered and thus have very limited lifetime. Energy efficiency has been the most important aspect to discuss when talking about wireless body area network (WBAN) in particular, since it is the bottleneck of these networks. Medium access control (MAC) protocols hold the vital position to determine the energy efficiency of a WBAN, which is a key design issue for battery operated sensor nodes. The wake-up radio (WUR) based MAC and physical layer (PHY) have been evaluated in this research work in order to contribute to the energy efficient solutions development. WUR is an on-demand approach in which the node is woken up by the wake-up signal (WUS). A WUS switches a node from sleep mode to wake up mode to start signal transmission and reception. The WUS is transmitted or received by a secondary radio transceiver, which operates on very low power. The energy benefit of using WUR is compared with conventional duty-cycling approach. As the protocol defines the nodes in WUR based network do not waste energy on idle listening and are only awakened when there is a request for communication, therefore, energy consumption is extremely low. The performance of WUR based MAC protocol has been evaluated for both physical layer (PHY) and MAC for transmission of WUS and data. The probabilities of miss detection, false alarm and detection error rates are calculated for PHY and the probabilities of collision and successful data transmission for channel access method Aloha is evaluated. The results are obtained to compute and compare the total energy consumption of WUR based network with duty cycling. The results prove that the WUR based networks have significant potential to improve energy efficiency, in comparison to conventional duty cycling approach especially, in the case of low data-reporting rate applications. The duty cycle approach is better than WUR approach when sufficiently low duty cycle is combined with highly frequent communication between the network nodes.

This thesis starts with an investigation of the interactions in terms of data flow between parties involved in body area networks or BANs under healthcare scenarios targeting outdoor and indoor environments. Using these scenarios, data flow requirements are identified between BAN elements and parties involved in BANs such as patients and doctors. Identified requirements are used to generate BAN data flow models. Data flow models and key information security and the privacy requirements were used to design an access control policy model that would allow authorized parties to access medical resources and data securely.

In this thesis we explore if a proposed random binary sequence generation algorithm can be combined with a separately proposed symmetric key agreement protocol to provide usable security for communications in Wireless Body Area Networks (WBAN). Other previous works in this area fall short by only considering key generation between two of the same signals or allowing for key generation between two different types of signals but with the cost of a significant signal collection time requirement. We hoped to advance this area of research by making secure key generation more efficient with less signal collection time and allowing keys to be generated between two sensors that measure two different physiological signals. However, while the binary sequence generation algorithm and key agreement protocol perform well separately, they do not perform well together. The combined approach yields keys that have good properties for use in a WBAN, but the generation rate is low.

Wireless body area networks (WBANs) have tremendous potential to benefit from wireless communication technology and are expected to make sweeping changes in the future human health care and medical fields. While the prospects for WBAN products are high, meeting required device performance with a meager amount of power consumption poses significant design challenges. In order to address these issues, IEEE has recently developed a draft of IEEE 802.15.6 standard dedicated to low bit-rate short-range wireless communications on, in, or around the human body. Commercially available SoC (System-on-Chip) devices targeted for WBAN applications typically embed proprietary wireless transceivers. However, those devices usually do not meet the quality of service (QoS), low power, and/or noninterference necessary for WBAN applications, nor meet the IEEE standard specifications. This dissertation presents a design of low-power RF front-end conforming to the IEEE standard in Medical Communication Service (MICS) band of 402-405 MHz. First, we investigated IEEE 802.15.6 PHY specifications for narrow band WBAN applications. System performance analysis and simulation for an AWGN (additive white Gaussian noise) channel was conducted to obtain the BER (bit error rate) and the PER (packet error rate) as the figure of merit. Based on the system performance study, the link budget was derived as a groundwork for our RF front-end design. Next, we examined candidate RF front-end architectures suitable for MICS applications. Based on our study, we proposed to adopt a direct conversion transmitter and a low-IF receiver architecture for the RF front-end. An asynchronous wake-up receiver was also proposed, which is composed of a carrier sensing circuit and a serial code detector. Third, we proposed and implemented low-power building blocks of the proposed RF front-end. Two quadrature signal generation techniques were proposed and implemented for generation of quadrature frequency sources. The two quadrature voltage controlled oscillators (QVCOs) were designed using our proposed current-reuse VCO with two damping resistors. A stacked LNA and a down-conversion mixer were proposed for low supply and low power operation for the receiver front-end. A driver amplifier and an up-conversion mixer for the transmitter front-end were implemented. The proposed driver amplifier uses cascaded PMOS transistors to minimize the Miller effect and enhance the input/output isolation. The up-conversion mixer is based on a Gilbert cell with resistive loads. Simulation results and performance comparisons for each designed building block are presented. Finally, we present a case study on a direct VCO modulation transmitter and a super-regenerative receiver, which can also be suitable for an MICS transceiver. Several crucial building blocks including a digitally-controlled oscillator (DCO) and quench signal generators are proposed and implemented with a small number of external components.
Ph. D.

This dissertation will present several novel techniques that use cooperation and diversity to improve the performance of multihop Wireless Sensor Networks, as measured by throughput, delay, and reliability, beyond what is achievable with conventional error control technology. We will investigate the applicability of these new technologies to Wireless Body Area Networks (WBANs) an important emerging class of wireless sensor networks. WBANs, which promise significant improvement in the reliability of monitoring and treating people's health, comprise a number of sensors and actuators that may either be implanted in vivo or mounted on the surface of the human body, and which are capable of wireless communication to one or more external nodes that are in close proximity to the human body. Our focus in this research is on enhancing the performance of WBANs, especially for emerging real-time in vivo traffic such as streaming real-time video during surgery. Because of the nature of this time-sensitive application, retransmissions may not be possible. Furthermore, achieving minimal energy consumption, with the required level of reliability is critical for the proper functioning of many wireless sensor and body area networks. Additionally, regardless of the traffic characteristics, the techniques we introduce strive to realize reliable wireless sensor networks using (occasionally) unreliable components (wireless sensor nodes). To improve the performance of wireless sensor networks, we introduce a novel technology Cooperative Network Coding, a technology that synergistically integrates the prior art of Network Coding with Cooperative Communications. With the additional goal of further minimizing the energy consumed by the network, another novel technology Cooperative Diversity Coding was introduced and is used to create protection packets at the source node. For representative applications, optimized Cooperative Diversity Coding or Cooperative Network Coding achieves ≥ 25% energy savings compared to the baseline Cooperative Network Coding scheme. Cooperative Diversity Coding requires lees computational complexity at the source node compared to Cooperative Network Coding. To improve the performance and increase the robustness and reliability of WBANs, two efficient feedforward error-control technologies, Cooperative Network Coding (CDC) and Temporal Diversity Coding (TDC), are proposed. Temporal Diversity Coding applies Diversity Coding in time to improve the WBAN's performance. By implementing this novel technique, it is possible to achieve significant improvement (50%) in throughput compared to extant WBANs. An example of an implementation of in vivo real-time application, where TDC can improve the communications performance, is the MARVEL (Miniature Anchored Robotic Videoscope for Expedited Laparoscopy) research platform developed at USF. The MARVEL research platform requires high bit rates (100 Mbps) for high-definition transmission. Orthogonal Frequency Division Multiplexing (OFDM), a widely used technology in fourth generation wireless networks (4G) that achieves high transmission rates over dispersive channels by transmitting serial information through multiple parallel carriers. Combining Diversity Coding with OFDM (DC-OFDM) promises high reliability communications while preserving high transmission rates. Most of the carriers transport original information while the remaining (few) carriers transport diversity coded (protection) information. The impact of DC-OFDM can extend far beyond in vivo video medical devices and other special purpose wireless systems and may find significant application in a broad range of ex vivo wireless systems, such as LTE, 802.11, 802.16.

Le réseau de capteurs porté est une technologie d’avenir prometteuse à multiple domaines d’application allant du médical à l’interface homme machine. Le projet BoWI a pour ambition d’évaluer la possibilité d’élaborer un réseau de capteurs utilisable au quotidien dans un large spectre d’applications et ergonomiquement acceptable pour le grand public. Cela induit la nécessité de concevoir un nœud de réseau ultra basse consommation pour à la fois convenir à une utilisation prolongée et sans encombrement pour le porteur. La solution retenue est de concevoir un nœud capable de travailler avec une énergie comparable à ce que l’état de l’art de la récolte d’énergie est capable de fournir. Une solution ASIC est privilégiée afin de tenir les contraintes d’intégration et de basse consommation. La conception de l’architecture dédiée a nécessité une étude préalable à plusieurs niveaux. Celle-ci comprend un état de l’art de la récolte d’énergie afin de fixer un objectif de budget énergie/puissance de notre système. Une étude des usages du système a été nécessaire notamment pour la reconnaissance postures afin de déterminer les cas d’applications types. Cette étude a conduit au développement d’algorithmes permettant de répondre aux applications choisies tout en s’assurant de la viabilité de leurs implantations. Le budget énergie fixé est un objectif de 100µW. Les applications choisies sont la reconnaissance de posture, la reconnaissance de geste et la capture de mouvement. Les solutions algorithmiques choisis sont une fusion de données de capteurs inertiels par Filtre de Kalman étendu (EKF) et l’ajout d’une classification par analyse en composante principale. La solution retenue pour obtenir des résultats d’implémentation est la synthèse de haut niveau qui permet un développement rapide. Les résultats de l’implantation matérielle sont dominés principalement par l’EKF. À la suite de l’étude, il apparait qu’il est possible avec une technologie 28nm d’atteindre les objectifs de budget énergie pour la partie algorithme. Une évaluation de la gestion haut niveau de tous les composants du nœud est également effectuée afin de donner une estimation plus précise des performances du système dans un cas d’application réel. Une contribution supplémentaire est obtenue avec l’ajout de la détection d’activité qui permet de prédire la charge de calcul nécessaire et d’adapter dynamiquement l’utilisation des ressources de traitement et des capteurs afin d’optimiser l’énergie en fonction de l’activité
Wireless Body Sensor Network (WBSN) is a promising technology that can be used in a lot of application domains from health care to Human Machine Interface (HMI). The BoWI project ambition is to evaluate and design a WBSN that can be used in various applications with daily usage and accessible to the public. This necessitates to design a ultra-low power node that reach a day of use without discomfort for the user. The elected solution is to design a node that operates with the power budget similar to what can be provided by the state of the art of the energy harvesting. An Application Specific Integrated Circuit (ASIC) solution is privileged in order to meet the integration and low power constraints. Designing the dedicated architecture required a preliminary study at several level which are: a state of the art of the energy harvesting in order to determine the objective of energy/power budget of our system, A study of the usage of the system to determine and select typical application cases. A study of the algorithms to address the selected applications while considering the implementation viability of the solutions. The power budget objective is set to 100µW. The application selected are the posture recognition, the gesture recognition and the motion capture. The algorithmic solution proposed are a data-fusion based on an Extended Kalman FIlter (EKF) with the addition of a classification using Principal Component Analysis (PCA). The implementation tool used to design the architecture is an High Level Synthesis (HLS) solution. Implementation results mainly focus on the EKF since this is by far the most power consuming digital part of the system. Using a 28nm technology the power budget objective can be reached for the algorithmic part. A study of the top level management of all components of the node is done in order to estimate performances of the system in real application case. This is possible using an activity detection which dynamically estimates the computing load required and then save a maximum of energy while the node is still

[ES] La población mundial en países desarrollados está envejeciendo y con ello existe un aumento de enfermedades en gran medida causadas por la edad. Las nuevas tecnologías médicas pueden ayudar a detectar, diagnosticar y tratar estas enfermedades y con ello ahorrar dinero, tiempo y recursos de los sistemas sanitarios. Las tecnologías inalámbricas implantables han abierto un nuevo panorama para la próxima generación de tecnologías médicas. Frecuencias como la Ultra Wide-Band (UWB) de 3.1 a 10.6 GHz están siendo consideradas para la nueva generación de dispositivos inalámbricos para dentro del cuerpo humano. Las características como el reducido tamaño de las antenas, la baja potencia de transmisión y la alta velocidad de datos son las más buscadas en este tipo de dispositivos. El problema surge porque el cuerpo humano depende de la frecuencia de modo que a mayores frecuencias, mayores son las pérdidas por propagación. Conociendo el canal de transmisión se puede solventar el problema de las altas pérdidas. Esta tesis tiene como objetivo caracterizar el canal de radio frecuencia (RF) para la nueva generación de dispositivos médicos implantables. Para caracterizar el canal se han empleado tres diferentes metodologías: simulaciones numéricas, medidas en phantom y experimentos en animales vivos. Las medidas en phantom fueron realizadas en un nuevo sistema de medidas expresamente disen¿ados para medidas de dentro a fuera del cuerpo humano en la banda de frecuencias UWB. Además, se utilizó un novedoso recipiente con dos capas de phantom imitando la zona gastrointestinal del cuerpo. Estos phantoms fueron creados para este tipo de medidas y son extremadamente precisos a las frecuencias UWB. Para los experimentos en animales se utilizaron cerdos y se intentó reproducir en ellos las medidas previamente realizadas en phantom. Las simulaciones software se realizaron con la intención de replicar ambas metodologías. Una vez realizados los experimentos se realizó un extensivo estudio del canal en dominio frecuencial y temporal. Mas en detalle, se compararon las antenas usadas en la recepción y transmisión, el efecto de la grasa en el canal, la formas del recipiente contenedor de phantom y las componentesmulticamino. Como resultado se ha propuesto un modelo de propagación del canal para la banda baja de las frecuencias UWB (3.1 -5.1 GHz) para la zona gastrointestinal del cuerpo humano. Este modelo de propagación ha sido validado utilizando las tres metodologías previamente descritas y comparada con otros estudios existentes en literatura. Finalmente, se midió el canal de propagación para una determinada aplicación a bajas frecuencias con señales UWB. También se realizaron medidas del canal de propagación en la zona cardíaca del cuerpo humano desde un punto de vista de seguridad de datos. Los resultados obtenidos en esta tesis confirman los beneficios que tendría la utilización de frecuencias UWB para las futuras generaciones de dispositivos médicos implantables.
[CA] La població mundial a països desenvolupats està envellint-se i enfrontant-se a un augment d'infermetats principalment causades per la edat. Les noves tecnologies mèdiques poden ajudar a detectar, diagnosticar i tractar aquestes malalties, estalviant diners, temps i recursos sanitaris. Els dispositius implantables sense fils han generat un nou panorama per a les noves generacions de dispositius mèdics. Les freqüències com la banda de UWB estan sent considerades per a les futures tecnologies implantables. La reduïda grandària de les antenes, la baixa potència de transmissió i les altes velocitats de dades son característiques buscades per als dispositius implantables. Per contra, els éssers humans depenen de la freqüència en el sentit que a majors freqüències, majors les pèrdues per propagació quan el senyal travessa el cos humà d'interior a exterior. Per solventar aquestes pèrdues el canal de propagació s'ha d'entendre i conèixer de la millor manera possible. Aquesta tesi doctoral te com a objectiu caracteritzar el canal de radio freqüència (RF) per a la nova generació de dispositius mèdics implantables. S'han emprat tres metodologies diferents per a realitzar aquesta caracterització: simulacions software, mesures amb fantomes i experiments amb animals vius. Els experiments amb fantomes es van realitzar a un sistema de mesures dissenyat expressament per a les transmissions de dins a fora del cos humà a les freqüències UWB. També es van utilitzar un contenidor per als fantomes de dues capes, imitant l'area gastrointestinal dels humans. Per als experiments a animals es van emprar porcs, replicant els experiments al laboratori en fantomes de la forma més semblant possible. Les simulacions software foren dissenyades per a imitar les experiments amb fantomes i animals. Després dels experiments el canal de propagació es va investigar exhaustivament des del domini freqüèncial i temporal. S'ha observat com les antenes en transmissió i recepció afecten al senyal, la influència de la grassa, la forma del contenidor de fantoma i les possibles contribucions multicamí. Finalment es proposa un nou model de propagació per a les baixes freqüències UWB (3.1 a 5.1 GHz) per a la zona GI del cos humà. El model es va validar utilitzant les tres metodologies abans esmentades i també foren comparades amb model ja existents a la literature. Finalment des d'un punt de vista aplicat, el canal es va avaluar per al senyal UWB a baixes freqüències (60 MHz). A més a més, per a la nova generació de marcapassos sense fil es va investigar el canal des d'un punt de vista de seguretat de dades. Els resultats obtinguts a aquesta tesi confirmen els avantatges d'emprar la banda de freqüències UWB per a la nova generació de dispositius médics implantables.
[EN] The current global population in developed countries is becoming older and facing an increase in diseases mainly caused by age. New medical technologies can help to detect, diagnose and treat illness, saving money, time, and resources of physicians. Wireless in-body devices opened a new scenario for the next generation of medical devices. Frequencies like the Ultra Wide-band (UWB) frequency band (3.1 - 10.6 GHz) are being considered for the next generation of in-body wireless devices. The small size of the antennas, the low power transmission, and the higher data rate are desirable characteristics for in-body devices. However, the human body is frequency ependent, which means higher losses of the radio frequency (RF) signal from in- to out-side the body as the frequency increases. To overcome this, the propagation channel has to be understood and known as much possible to process the signal accordingly. This dissertation aims to characterize the (RF) channel for the future of in-body medical devices. Three different methodologies have been used to characterize the channel: numerical simulations, phantom measurements, and living animals experiments. The phantom measurements were performed in a novel testbed designed for the purpose of in-body measurements at the UWB frequency band. Moreover, multi-layer high accurate phantoms mimicking the gastrointesintal (GI) area were employed. The animal experiments were conducted in living pigs, replicating in the fairest way as possible the phantom measurement campaigns. Lastly, the software simulations were designed to replicate the experimental measurements. An in-depth and detail analysis of the channel was performed in both, frequency and time domain. Concretely, the performance of the receiving and transmitting antennas, the effect of the fat, the shape of the phantom container, and the multipath components were evaluated. Finally, a novel path loss model was obtained for the low UWB frequency band (3.1 - 5.1 GHz) at GI scenarios. The model was validated using the three methodologies and compared with previous models in literature. Finally, from a practical case point of view, the channel was also evaluated for UWB signals at lower frequencies (60 MHz) for the GI area. In addition, for the next generation of leadless pacemakers the security link between the heart and an external device was also evaluated. The results obtained in this dissertation reaffirm the benefits of using the UWB frequency band for the next generation of wireless in-body medical devices.
Pérez Simbor, S. (2019). In-body to On-body Experimental UWB Channel Characterization for the Human Gastrointestinal Area [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/133034
TESIS

Recent technological advances in wireless communications, mobile computation, and sensor technologies have enabled the development of low-cost, miniature, lightweight,intelligent wireless sensor devices or “motes”. A collection of these devices can beplaced strategically on the key positions of the human body and connected by meansof a wireless network to form a Wireless Body Area Network (WBAN).

WBAN has recently attracted a great deal of attention from researchers both inacademia as well as industry. This is primarily due to its unique capabilities and promising applications in areas like healthcare, fitness, sports, military and security. Inthe healthcare domain, WBAN promises to revolutionize healthcare system throughallowing inexpensive, unobtrusive, non-invasive, ambulatory monitoring of human’shealth-status anytime, anywhere.

In this thesis, we propose a WBAN-based prototype system for remotely monitoring mobile user’s physical activities and health-status via the Internet. The system consistsof a WBAN and a remote monitoring server (RS). The WBAN comprises a personalserver (PS) and a number of custom-made wireless sensor nodes each featuring amotion sensor for monitoring physical activity, and a temperature sensor formonitoring body temperature. The PS is a minicomputer equipped with a GPSreceiver for tracking and monitoring user’s location, a ZigBee module forcommunication with the sensor nodes, and a GPRS module for communication withthe RMS. The RMS is an internet enabled PC.

The sensors measure body motions and temperature and send the measurement datato the PS via a ZigBee network. The PS collects the data, process them and uploadsthem via GPRS to the RMS where the data can be visualized and displayed for userinspection and/or stored in a filesystem/database for post analysis.

Currently the system is in a prototype phase and is developed as a proof-of-concept.The proposed system, once perfected, can be used in different application scenarios.For example, for remotely monitoring elderly people, people with disabilities, patientsundergoing physical rehabilitations, athletes or soldiers during training/exercises, etc.

Doctor of Philosophy
Department of Electrical & Computer Engineering
Steve Warren
The U.S. health care system is one of the most advanced and costly systems in the world. The health services supply/demand gap is being enlarged by the aging population coupled with shortages in the traditional health care workforce and new information technology workers. This will not change if the current medical system adheres to the traditional hospital-centered model. One promising solution is to incorporate patient-centered, point-of-care test systems that promote proactive and preventive care by utilizing technology advancements in sensors, devices, communication standards, engineering systems, and information infrastructures. Biomedical devices optimized for home and mobile health care environments will drive this transition. This dissertation documents research and development focused on biomedical device design for this purpose (including a wearable wireless pulse oximeter, motion sensor, and two-thumb electrocardiograph) and, more importantly, their interactions with other medical components, their supporting information infrastructures, and processing tools that illustrate the effectiveness of their data. The GumPack concept and prototype introduced in Chapter 2 addresses these aspects, as it is a sensor-laden device, a host for a local body area network (BAN), a portal to external integration frameworks, and a data processing platform. GumPack sensor-component design (Chapters 3 and 4) is oriented toward surface applications (e.g., touch and measure), an everyday-carry form factor, and reconfigurability. Onboard tagging technology (Chapters 5 and 6) enhances sensor functionality by providing, e.g., a signal quality index and confidence coefficient for itself and/or next-tier medical components (e.g., a hub). Sensor interaction and integration work includes applications based on the GumPack design (Chapters 7 through 9) and the Medical Device Coordination Framework (Chapters 10 through 12). A high-resolution, wireless BAN is presented in Chapter 8, followed by a new physiological use case for pulse wave velocity estimation in Chapter 9. The collaborative MDCF work is transitioned to a web-based Hospital Information Integration System (Chapter 11) by employing database, AJAX, and Java Servlet technology. Given the preceding sensor designs and the availability of information infrastructures like the MDCF, medical platform-oriented devices (Chapter 12) could be an innovative and efficient way to design medical devices for hospital and home health care applications.

Les réseaux corporels (WBAN) se réfère aux réseaux de capteurs (WSN) "portables" utilisés pour collecter des données personnelles, telles que la fréquence cardiaque ou l'activité humaine. Cette thèse a pour objectif de proposer des algorithmes coopératifs (PHY/MAC) pour effectuer des applications de localisation, tels que la capture de mouvement et la navigation de groupe. Pour cela, nous exploitons les avantages du WBAN avec différentes topologies et différents types de liens: on-body à l'échelle du corps, body-to-body entre les utilisateurs et off-body par rapport à l'infrastructure. La transmission repose sur une radio impulsionnelle (IR-UWB), afin d'obtenir des mesures de distance précises, basées sur l’estimation du temps d'arrivée (TOA). Ainsi, on s’intéresse au problème du positionnement à travers de la conception de stratégies coopératives et en considérant la mobilité du corps et les variations canal. Notre première contribution consiste en la création d'une base de données obtenue avec de scénarios réalistes pour la modélisation de la mobilité et du canal. Ensuite, nous introduisons un simulateur capable d'exploiter nos mesures pour la conception de protocoles. Grâce à ces outils, nous étudions d’abord l'impact de la mobilité et des variations de canal sur l'estimation de la distance avec le protocole "three way-ranging" (3-WR). Ainsi, nous quantifions et comparons l'erreur avec des modèles statistiques. Dans un second temps, nous analysons différentes algorithmes de gestion de ressources pour réduire l'impact de la mobilité sur l'estimation de position. Ensuite, nous proposons une optimisation avec un filtre de Kalman étendu (EKF) pour réduire l'erreur. Enfin, nous proposons un algorithme coopératif basé sur l'analyse d’estimateurs de qualité de lien (LQEs) pour améliorer la fiabilité. Pour cela, nous évaluons le taux de succès de positionnement en utilisant trois modèles de canaux (empirique, simulé et expérimental) avec un algorithme (basé sur la théorie des jeux) pour le choix des ancres virtuelles
Wireless Body Area Networks (WBAN) refers to the family of “wearable” wireless sensor networks (WSN) used to collect personal data, such as human activity, heart rate, sleep sequences or geographical position. This thesis aims at proposing cooperative algorithms and cross-layer mechanisms with WBAN to perform large-scale individual motion capture and coordinated group navigation applications. For this purpose, we exploit the advantages of jointly cooperative and heterogeneous WBAN under full/half-mesh topologies for localization purposes, from on-body links at the body scale, body-to-body links between mobile users of a group and off-body links with respect to the environment and the infrastructure. The wireless transmission relies on an impulse radio Ultra-Wideband (IR-UWB) radio (based on the IEEE 802.15.6 standard), in order to obtain accurate peer-to-peer ranging measurements based on Time of Arrival (ToA) estimates. Thus, we address the problem of positioning and ranging estimation through the design of cross-layer strategies by considering realistic body mobility and channel variations. Our first contribution consists in the creation of an unprecedented WBAN measurement database obtained with real experimental scenarios for mobility and channel modelling. Then, we introduce a discrete-event (WSNet) and deterministic (PyLayers) co-simulator tool able to exploit our measurement database to help us on the design and validation of cooperative algorithms. Using these tools, we investigate the impact of nodes mobility and channel variations on the ranging estimation. In particular, we study the “three-way ranging” (3-WR) protocol and we observed that the delays of 3-WR packets have an impact on the distances estimated in function of the speed of nodes. Then, we quantify and compare the error with statistical models and we show that the error generated by the channel is bigger than the mobility error. In a second time, we extend our study for the position estimation. Thus, we analyze different strategies at MAC layer through scheduling and slot allocation algorithms to reduce the impact of mobility. Then, we propose to optimize our positioning algorithm with an extended Kalman filter (EKF), by using our scheduling strategies and the statistical models of mobility and channel errors. Finally, we propose a distributed-cooperative algorithm based on the analysis of long-term and short-term link quality estimators (LQEs) to improve the reliability of positioning. To do so, we evaluate the positioning success rate under three different channel models (empirical, simulated and experimental) along with a conditional algorithm (based on game theory) for virtual anchor choice. We show that our algorithm improve the number of positions estimated for the nodes with the worst localization performance

Short range wireless data communication networks that are used for sport and health care are sometimes called Wireless Body Area Networks (WBANs) and they are located more or less on a person. Sole Integrated Gait Sensor (SIGS) is a research project in WBAN, where wireless pressure sensors are placed like soles in the shoes of persons with different kinds of deceases. The sensors can measure the pressure of the foot relative to the shoe i.e. the load of the two legs is measured. This information can be useful e.g. to not over or under load a leg after joint replacement or as a bio feedback system to help e.g. post stroke patients to avoid falling. The SIGS uses the ANT Protocol and radio specification. ANT uses the 2.4 GHz ISM band and TDMA is used to share a single frequency. The scheduling of time slots is adaptive isochronous co-existence i.e. the scheduling is not static and each transmitter sends periodically but checks for interference with other traffic on the radio channel. In this unidirectional system sole sensors are masters (transmitters) and the WBAN server is the slave in ANT sense. The message rate is chosen as 8 Hz which is suitable for low power consumption. Hence in the SIGS system, it is necessary to synchronize the left and the right foot sensors because of low message rate. In our thesis, we found a method and developed a prototype to receive the time synchronized data in WBAN server from ANT wireless sensor nodes in SIGS system. For this thesis work, a hardware prototype design was developed. The USB and USART communication protocols were also implemented in the hardware prototype. The suitable method for time synchronization was implemented on the hardware prototype. The implemented method receives the sensor data, checks for the correct stream of data; add timestamp to the sensor data and transmit the data to the Linux WBAN server. The time slots allocation in the ANT protocol was found. Alternative solution for the time synchronization in ANT protocol was also provided. The whole SIGS system was tested for its full functionality. The experiments and analysis which we performed were successful and the results obtained provided good time synchronization protocol for ANT low power wireless sensor network and for Wireless Bio-feedback system.

Cooperative wireless communication is an attractive technique to explore the spatial channel resources by coordination across multiple links, which can greatly improve the communication performance over single links. In this dissertation, we study the cooperative multi-link channel properties by geometric approaches in body area networks (BANs) and cellular networks respectively.

In the part of BANs, the dynamic narrowband on-body channels under body motions are modeled statistically on their temporal and spatial fading based on anechoic and indoor measurements. Common body scattering is observed to form inter-link correlation between links closely distributed and between links having synchronized movements of communication nodes. An analytical model is developed to explain the physical mechanisms of the dynamic body scattering. The on-body channel impacts to simple cooperation protocols are evaluated based on realistic measurements.

In the part of cellular networks, the cluster-level multi-link COST 2100 MIMO channel model is developed with concrete modeling concepts, complete parameterization and implementation methods, and a compatible structure for both single-link and multi-link scenarios. The cluster link-commonness is introduced to the model to describe the multi-link properties. The multi-link impacts by the model are also evaluated in a distributed MIMO system by comparing its sum-rate capacity at different ratios of cluster link-commonness.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

In this thesis, a novel graphene (GN) based electrocardiogram (ECG) sensor is designed, constructed and tested to validate the concept of coating GN, which is a highly electrically conductive material, on Ag substrates of conventional electrodes. The background theory, design, experiments and results for the proposed GN-based ECG sensor are also presented. Due to the attractive electrical and physical characteristics of graphene, a new ECG sensor was investigated by coating GN onto itself. The main focus of this project was to examine the effect of GN on ECG monitoring and to compare its performance with conventional methods. A thorough investigation into GN synthesis on Ag substrate was conducted, which was accompanied by extensive simulation and experimentation. A GN-enabled ECG electrode was characterised by Raman spectroscopy, scanning electron microscopy along with electrical resistivity and conductivity measurements. The results obtained from the GN characteristic experimentation on Raman spectroscopy, detected a 2D peak in the GN-coated electrode, which was not observed with the conventional Ag/AgCl electrode. SEM characterisation also revealed that a GN coating smooths the surface of the electrode and hence, improves the skin-to-electrode contact. Furthermore, a comparison regarding the electrical conductivity calculation was made between the proposed GN-coated electrodes and conventional Ag/AgCl ones. The resistance values obtained were 212.4 Ω and 28.3 Ω for bare and GN-coated electrodes, respectively. That indicates that the electrical conductivity of GN-based electrodes is superior and hence, it is concluded that skin-electrode contact impedance can be lowered by their usage. Additional COMSOL simulation was carried out to observe the effect of an electrical field and surface charge density using GN-coated and conventional Ag/AgCl electrodes on a simplified human skin model. The results demonstrated the effectiveness of the addition of electrical field and surface charge capabilities and hence, coating GN on Ag substrates was validated through this simulation. This novel ECG electrode was tested with various types of electrodes on ten different subjects in order to analyse the obtained ECG signals. The experimental results clearly showed that the proposed GN-based electrode exhibits the best performance in terms of ECG signal quality, detection of critical waves of ECG morphology (P-wave, QRS complex and T-wave), signal-to-noise ratio (SNR) with 27.0 dB and skin-electrode contact impedance (65.82 kΩ at 20 Hz) when compared to those obtained by conventional a Ag/AgCl electrode. Moreover, this proposed GN-based ECG sensor was integrated with core body temperature (CBT) sensor in an ear-based device, which was designed and printed using 3D technology. Subsequently, a finger clipped photoplethysmography (PPG) sensor was integrated with the two-sensors in an Arduino based data acquisition system, which was placed on the subject's arm to enable a wearable multiple physiological measurement system. The physiological information of ECG and CBT was obtained from the ear of the subject, whilst the PPG signal was acquired from the finger. Furthermore, this multiple physiological signal was wirelessly transmitted to the smartphone to achieve continuous and real-time monitoring of physiological signals (ECG, CBT and PPG) on a dedicated app developed using the Java programming language. The proposed system has plenty of room for performance improvement and future development will make it adaptabadaptable, hence being more convenient for the users to implement other applications than at present.

Taking into account modern trends, the analysis of the construction principles of telemadic systems, networks and complexes is presented in the work. The general structure of providing telemedicine services is developed. Structures of realization of portable and mobile telemedicine complexes are offered. Infocommunication systems and networks for implementation in mobile telemedicine complexes are analyzed. The advantages of using the sensor mobile body area network of the IEEE 802.15.6 WBAN standard in mobile telemedicine complexes are justified.

Abstract The Internet of Things (IoT) is already providing solutions to various tasks related to monitoring the environment and controlling devices over wired and wireless networks. It is estimated by several well-known research facilities that the number of IoT devices will be in the order of tens of billions by 2020. This inevitably brings challenges and costs in deployment, management, and maintenance of networks. The focus of this thesis is to provide solutions that mainly help in the deployment and maintenance of various wireless IoT networks. Different applications have different requirements for a wireless link coverage. It is important to utilize suitable radio technology for a particular application in order, e.g., to maximize the lifetime of a device. A wireless body area network (WBAN) typically consists of devices that are within couple of meters from each other. The WBAN is suitable for, e.g., measuring muscle activity and transferring data to a storage for processing. The wireless link can use air as a medium, or alternatively, an induced electric field to a body can be used. In this thesis, it is shown that a location of the electrodes in the body have impact to the attenuation. Home automation IoT applications are typically implemented with mid-range wireless technologies, known as wireless personal area networks (WPAN). In order to minimize and get rid of battery change operations, a wake-up receiver could be utilized in order to improve the device’s energy efficiency. The concept is introduced and performance of the current state-of-the-art works are presented. In addition, a control loop enabling a passive device to have control over an energy source is proposed. Applications that have low bandwidth requirements can be implemented with low-power wide area networks (LPWAN). One technology – LoRaWAN – is evaluated, and it is recommended as based on the results to use it in non-critical applications
Tiivistelmä Esineiden internet (Internet of Things, IoT) mahdollistaa jo laajan kirjon erilaisia ratkaisuja ympäristön monitorointiin ja laitteiden hallintaan hyödyntäen sekä langattomia että langallisia verkkoja. Usea hyvin tunnettu tutkimusorganisaatio on arvioinut, että vuonna 2020 IoT laitteiden määrä tulee olemaan kymmenissä miljardeissa. Se luo väistämättä haasteita laitteiden sijoittamisessa, hallinnassa ja kunnossapidossa. Tämä väitöskirja keskittyy tarjoamaan ratkaisuja, jotka voivat helpottaa langattomien IoT laitteiden sijoittamisessa ja kunnossapidossa. IoT sovellusten laaja kirjo vaatii erilaisia langattomia radioteknologioita, jotta sovellukset voitaisiin toteuttaa, muun muassa, mahdollisimman energiatehokkaasti. Langattomassa kehoverkossa (wireless body area network, WBAN) käytetään usein hyvin lyhyitä langattomia linkkejä. WBAN on soveltuva esimerkiksi lihasten aktiivisuus mittauksessa ja mittaustiedon siirtämisessä talteen varastointia ja prosessointia varten. Linkki voidaan toteuttaa käyttäen ilmaa rajapintana, tai vaihtoehtoisesti, kehoa. Tässä työssä on näytetty, että käytettäessä kehoa siirtotienä, elektrodien sijainnilla on merkitystä signaalin vaimennuksen kannalta. Kotiautomaatio IoT sovellukset ovat tyypillisesti toteutettu käyttäen langatonta likiverkkoa, jossa linkin pituus sisätiloissa on alle 30 metriä. Jotta päästäisiin eroon pariston vaihto-operaatiosta tai ainakin vähennettyä niiden määrää, herätevastaanotinta käyttämällä olisi mahdollista parantaa laitteiden energiatehokkuutta. Herätevastaanotin konsepti ja tämänhetkistä huipputasoa edustavien vastaanottimien suorituskyky ovat esitetty. Lisäksi, on ehdotettu menetelmä joka takaa energian saannin passiiviselle IoT laitteelle. IoT sovellukset jotka tyytyvät vähäiseen kaistanleveyteen voidaan toteuttaa matalatehoisella laajan alueen verkolla (low-power wide area network, LPWAN). Yhden LPWAN teknologian, nimeltään LoRaWAN, suorituskykyä on evaluoitu. Tulosten perusteella suositus on hyödyntää kyseistä teknologiaa ei-kriittisissä sovelluksissa

Abstract This thesis proposes cross-layer approaches which enable to improve energy efficiency of wireless sensor networks and wireless body area networks (WSN & WBAN). The focus is on the physical (PHY) and medium access control (MAC) layers of communication protocol stack and exploiting their interdependencies. In the analysis of the PHY and MAC layers, their relevant characteristics are taken into account, and cross-layer models are developed to study the effect of these layers on energy efficiency. In addition, cross-layer analysis is applied at the network level by addressing hierarchical networks' energy efficiency. The objective is to improve energy efficiency by taking into account that substantial modifications to current standards and techniques are not required to take advantage of the proposed methods. The studied scenarios of WSN take advantage of the wake-up radio (WUR). A generic WUR-based MAC (GWR-MAC) protocol with objective to improve energy efficiency by avoiding idle listening is proposed. First, the proposed cross-layer model is developed at a general level and applied to study the forward error correction (FEC) code rate selection effect on the length of the transmission period and energy efficiency in a star topology network. Then an energy efficiency model for intelligent hierarchical architecture based on GWR-MAC is proposed and performance comparison with a duty-cycle radio (DCR) approach is performed. Interactions between different layers' devices are taken into account, and the WUR and DCR approaches are compared as a function of event frequency. The third cross-layer model focuses on the effect of the FEC code rate and data packet payload length on the energy efficiency of the IEEE Std 802.15.6-based WBANs using IR-UWB PHY. The results acquired by using analytical modelling and simulations with the Matlab software clearly illustrates the potential energy gains that can be achieved with the proposed cross-layer approaches. The developed WUR-based MAC protocol, analytical models and achieved results can be exploited by other researchers in the WSN and WBAN field. The contribution of this thesis is also to stimulate further research on these timely topics and foster development of short-range communication, which has a crucial role in future converging networks such as the Internet of Things
Tiivistelmä Tässä väitöskirjassa ehdotetaan protokollakerrosten välistä tietoa hyödyntäviä (cross-layer) lähestymistapoja, jotka mahdollistavat energiatehokkuuden parantamisen langattomissa sensori- ja kehoverkoissa. Työ kohdistuu fyysisen- ja kanavanhallintakerroksen välisen vuorovaikutuksen tutkimiseen. Fyysisen- ja kanavanhallintakerrosten analyysissä huomioidaan niiden tärkeimmät ominaisuudet ja tutkitaan kerrosten yhteistä energiatehokkuutta. Lisäksi kerrosten välistä analyysiä sovelletaan verkkotasolle tutkimalla hierarkkisen verkon energiatehokkuutta. Tavoitteena on energiatehokkuuden parantamisen mahdollistaminen siten, että merkittäviä muutoksia nykyisiin standardeihin ja tekniikoihin ei tarvitse tehdä hyödyntääkseen ehdotettuja menetelmiä. Tutkitut sensoriverkkoskenaariot hyödyntävät heräteradiota. Väitöskirjassa ehdotetaan geneerinen heräteradiopohjainen kanavanhallintaprotokolla (GWR-MAC), jolla parannetaan energiatehokkuutta vähentämällä turhaa kanavan kuuntelua. Kerrosten välinen malli kehitetään ensin yleisellä tasolla ja sen avulla tutkitaan virheenkorjauskoodisuhteen valinnan vaikutusta lähetysperiodin pituuteen ja energiatehokkuuteen tähtitopologiaan pohjautuvissa sensoriverkoissa. Sitten väitöskirjassa ehdotetaan energiatehokkuusmalli älykkäälle GWR-MAC -protokollaan perustuvalle hierarkkiselle arkkitehtuurille ja sen suorituskykyä vertaillaan toimintajaksoperiaatteella toimivaan lähestymistapaan. Eri kerroksilla olevien laitteiden väliset vuorovaikutukset huomioidaan heräteradio- ja toimintajaksoperiaatteella toimivien verkkojen suorituskykyvertailussa tapahtumatiheyden funktiona. Kolmas malli kohdistuu virheenkorjauskoodisuhteen ja datapaketin hyötykuorman pituuden energiatehokkuusvaikutuksen tutkimiseen IEEE 802.15.6 -standardiin perustuvissa langattomissa kehoverkoissa. Analyyttinen mallinnus ja Matlab-ohjelmiston avulla tuotetut simulointitulokset osoittavat selvästi energiatehokkuushyödyt, jotka saavutetaan ehdotettuja menetelmiä käyttämällä. Kehitetty GWR-MAC -protokolla, analyyttiset mallit ja tulokset ovat hyödynnettävissä sensori- ja kehoverkkotutkijoiden toimesta. Tämän väitöskirjan tavoitteena on myös näiden ajankohtaisten aiheiden jatkotutkimuksen stimulointi sekä lyhyen kantaman viestinnän kehityksen vauhdittaminen, sillä niillä on erittäin merkittävä rooli tulevaisuuden yhteen liittyvissä verkoissa, kuten esineiden ja asioiden Internetissä

Abstract Impulse radio ultra-wideband (IR-UWB) technology, due to its baseband signaling, potentially offers a low cost, low complexity and low power consumption option for different short range sensor network applications. These sensor networks can be applied to many kinds of future implementations, including the Internet of Things (IoT) applications. In the medical and healthcare context, the term wireless body area network (WBAN) is often used, but, as mentioned, the wireless technology itself can be applied to any kind of body, e.g., to car or robot body networks. This thesis studies IR-UWB receivers’ performances in different hospital environment channel models by means of computer simulation. The main focus is on receivers that are capable of detecting the signals specified either in the IEEE 802.15.4-2015 or in the IEEE 802.15.6-2012 standards. The used channel models from two independent research groups include both on-body to on-body and on-body to off-body scenarios in different hospital environments. The evaluations and comparisons of various receivers include energy detector (ED) and rake receivers, the latter with both selective- and partial-rake structures. One of the studied receiver structures is further analyzed as it was noticed that the simulation results did not correspond to the assumed theoretical bit error probability (BEP) curves. Along the standards based studies, some modifications are also suggested for the two existing IR-UWB standards for increased compatibility and improved performance. One of the propositions resulted a Patent Cooperation Treaty (PCT) patent application. Additionally, an extensive survey is provided offering a compilation which includes presentations of IR-UWB research by other researchers, existing standards’ IR-UWB physical layer (PHY) specifications and the main global regulations concerning UWB
Tiivistelmä Erittäin laajakaistainen impulssiradioteknologia (IR-UWB) tarjoaa potentiaalisen vaihtoehdon yksinkertaisille, edullisille ja matalan tehonkulutuksen omaaville lähetin-vastaanotin-ratkaisuille, jotka soveltuvat lyhyen kantaman sensoriverkkoihin. Nämä sensoriverkot ovat monikäyttöisiä soveltuen esimerkiksi tulevaisuuden esineiden internetin (IoT) tiedonsiirtoratkaisuiksi. Esimerkiksi sairaanhoidon ja terveydenhuollon asiayhteyksissä käytetään monesti termiä langaton kehoverkko (WBAN), joka voidaan asentaa monenlaisiin eri sovelluskohteisiin kuten autoon tai vaikkapa robotin "keholle". Tässä väitöskirjassa on tutkittu tietokonesimulaatioiden avulla erilaisten IR-UWB vastaanotinrakenteiden suorituskykyä sairaalaympäristöä mallintavissa radiokanavissa. Tutkimuksen painopiste on vastaanottimissa, jotka kykenevät vastaanottamaan joko IEEE 802.15.4-2015- tai IEEE 802.15.6-2012-standardeissa määritellyn signaalin. Sairaalaympäristöä mallintavat radiokanavat perustuvat kahden toisistaan riippumattoman tutkijaryhmän mallinnuksiin, jotka sisältävät sekä keholta-keholle että keholta-kehon ulkopuolelle -radiokanavamallit. Energiailmaisin (ED) ja erilaiset harava-vastaanottimet ovat niitä vastaanotinrakenteita, joita tähän väitöskirjaan kuuluvissa artikkeleissa on arvioitu ja vertailtu. Yhtä vastaanotinrakennetta on myös analysoitu tarkemmin, kun havaittiin, etteivät kyseistä rakennetta koskevat simulaatiotulokset vastanneet oletettuja teoreettisia bittivirhetodennäköisyyksiä. Tutkimuksessa kehitettiin lisäksi olemassa olevien standardien ratkaisuihin liittyviä parannusehdotuksia, joita esitettiin muutamissa tähän väitöskirjaan sisällytetyissä artikkeleissa. Yhdestä ehdotuksesta tehtiin myös PCT-sopimuksen alainen patentointihakemus. Lisäksi yhdessä tähän väitöskirjaan sisällytetyssä artikkelissa on paitsi laaja kirjallisuuskatsaus sisältäen katsauksen muiden tekemiin IR-UWB- tutkimuksiin, myös olemassa olevien standardien fyysisten kerroksien määritykset koskien IR-UWB-teknologiaa ja tärkeimmät maailmanlaajuiset UWB-tekniikkaa koskevat signaalin tehotiheysmääräykset

The FCC allocated the spectrum of 402-405 MHz for MICS (Medical Implant Communication Services) applications in 1999. The regulations for MICS band apply to devices that support the diagnostic and/or therapeutic functions associated with implanted medical electronics. The implanted devices aid organs and control body functions of patients to support specific treatments, and monitor patients continuously so that necessary action can be taken in advance to avoid serious conditions. To enable to use MICS applications, several requirements must be satisfied. An implanted wireless device should have a small size, consume ultra-low power, and achieve the date rate of at least 200 kbps within 2 m distance. The major challenge is to realize ultra-low power devices. Thus the low-power design of the RF circuit is crucial for MICS applications as the power consumption of the wireless devices is mostly contributed by RF circuits. This thesis investigates low-power design of an LNA and a down-conversion mixer of a receiver for MICS applications. The key idea is to stack an LNA and a mixer, while the LNA operates in the normal super-threshold region and the mixer in the sub-threshold region. In addition, a gm-boosting technique with a capacitor cross-coupled at the LNA input stage is also adopted to achieve a low noise figure (NF) and high linearity, which is critical to the overall performance of the receiver. The mixer operating in the sub-threshold region significantly reduces power dissipation and relaxes the voltage headroom without sacrificing the LNA performance. The relaxed voltage headroom enables stack of the LNA and the mixer with a low supply voltage of 1.2 V. The proposed circuit is designed in 0.18 μm RF CMOS technology. The merged LNA and mixer consumes only 1.83 mW, and achieves 21.6 dB power gain. The NF of the block is 3.55 dB at 1 MHz IF, and the IIP3 is -6.08 dBm.
Master of Science

The use of autonomous robots in our society is increasing every day and a robot is no longer seen as a tool but as a team member. The robots are now working side by side with us and provide assistance during dangerous operations where humans otherwise are at risk. This development has in turn increased the need of robots with more human-awareness. Therefore, this master thesis aims at contributing to the enhancement of human-aware robotics. Specifically, we are investigating the possibilities of equipping autonomous robots with the capability of assessing and detecting activities in human teams. This capability could, for instance, be used in the robot's reasoning and planning components to create better plans that ultimately would result in improved human-robot teamwork performance. we propose to improve existing teamwork activity recognizers by adding intangible features, such as stress, motivation and focus, originating from human behavior models. Hidden markov models have earlier been proven very efficient for activity recognition and have therefore been utilized in this work as a method for classification of behaviors. In order for a robot to provide effective assistance to a human team it must not only consider spatio-temporal parameters for team members but also the psychological.To assess psychological parameters this master thesis suggests to use the body signals of team members. Body signals such as heart rate and skin conductance. Combined with the body signals we investigate the possibility of using System Dynamics models to interpret the current psychological states of the human team members, thus enhancing the human-awareness of a robot.
Användningen av autonoma robotar i vårt samhälle ökar varje dag och en robot ses inte längre som ett verktyg utan som en gruppmedlem. Robotarna arbetar nu sida vid sida med oss och ger oss stöd under farliga arbeten där människor annars är utsatta för risker. Denna utveckling har i sin tur ökat behovet av robotar med mer människo-medvetenhet. Därför är målet med detta examensarbete att bidra till en stärkt människo-medvetenhet hos robotar. Specifikt undersöker vi möjligheterna att utrusta autonoma robotar med förmågan att bedöma och upptäcka olika beteenden hos mänskliga lag. Denna förmåga skulle till exempel kunna användas i robotens resonemang och planering för att ta beslut och i sin tur förbättra samarbetet mellan människa och robot. Vi föreslår att förbättra befintliga aktivitetsidentifierare genom att tillföra förmågan att tolka immateriella beteenden hos människan, såsom stress, motivation och fokus. Att kunna urskilja lagaktiviteter inom ett mänskligt lag är grundläggande för en robot som ska vara till stöd för laget. Dolda markovmodeller har tidigare visat sig vara mycket effektiva för just aktivitetsidentifiering och har därför använts i detta arbete. För att en robot ska kunna ha möjlighet att ge ett effektivt stöd till ett mänskligtlag måste den inte bara ta hänsyn till rumsliga parametrar hos lagmedlemmarna utan även de psykologiska. För att tyda psykologiska parametrar hos människor förespråkar denna masteravhandling utnyttjandet av mänskliga kroppssignaler. Signaler så som hjärtfrekvens och hudkonduktans. Kombinerat med kroppenssignalerar påvisar vi möjligheten att använda systemdynamiksmodeller för att tolka immateriella beteenden, vilket i sin tur kan stärka människo-medvetenheten hos en robot.

The thesis work was conducted in Stockholm, Kista at the department of Informatics and Aero System at Swedish Defence Research Agency.