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.

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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

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.

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.

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. / The PhD investigations aim at exploring new WBAN cooperative localization mechanisms, which could benefit jointly from on-body links, body-to-body links between distinct mobile users or off-body links with respect to the infrastructure. Following a multidisciplinary approach, we have thus addressed theoretical questions related to physical modeling or to algorithmic and cross-layer design. A few more practical aspects have also been dealt with. More specifically, based on WBAN channel measurements, single-link ranging error models are first discussed for more realistic performance assessment. Then a Constrained Distributed Weighted Multi-Dimensional Scaling (CDWMDS) positioning algorithm is put forward for relative MoCap purposes, coping with on-body nodes' asynchronism to reduce system latency and exploiting the presence of constant-length radio links for better accuracy. Subsequently we consider extending this algorithm for larger-scale asbolute MoCap applications within a 2-step localization approach that incorporates additional off-body links in a heterogeneous WBAN framework. Then, both individual and collective kinds of navigation are addressed. In both MoCap and navigation scenarios, low-complexity solutions exploiting on-body deployment diversity enable to combat error propagation and strong range biases due to body shadowing, relying on on-body nodes' dispersion or graph neighborhood to approximate the corrupted distances. Finally, experiments based on real IR-UWB radio platforms validate in part the previous proposals, while showing their practical limitations.

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

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.

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.

The trend towards personalized ubiquitous computing has led to the advent of a new generation of wireless technologies, namely wireless body area networks (WBANs), which connect the wearable devices into the Internet-of-Things. This thesis considers the problems of relay selection and power control in fading WBANs with energy-efficiency and security considerations. The main body of the thesis is formed by two papers. Ideas from probability theory are used, in the first paper, to construct a performance measure signifying the energy efficiency of transmission, while in the second paper, information-theoretic principles are leveraged to characterize the transmission secrecy at the wireless physical layer (PHY). The hypothesis is that exploiting spatial diversity through multi-hop relaying is an effective strategy in a WBAN to combat fading and enhance communication throughput. In order to analytically explore the problems of optimal relay selection and power control, proper tools from game theory are employed. In particular, non-cooperative game-theoretic frameworks are developed to model and analyze the strategic interactions among sensor nodes in a WBAN when seeking to optimize their transmissions in the uplink. Quality-of-service requirements are also incorporated into the game frameworks, in terms of upper bounds on the end-to-end delay and jitter incurred by multi-hop transmission, by borrowing relevant tools from queuing theory. The proposed game frameworks are proved to admit Nash equilibria, and distributed algorithms are devised that converge to stable Nash solutions. The frameworks are then evaluated using numerical simulations in conditions approximating actual deployment of WBANs. Performance behavior trade-offs are investigated in an IEEE 802.15.6-based ultra wideband WBAN considering various scenarios. The frameworks show remarkable promise in improving the energy efficiency and PHY secrecy of transmission, at the expense of an admissible increase in the end-to-end latency.