Gait analysis is the systematic study of human walking. Clinical gait analysis is the process by which quantitative information is collected for the assessment and decision-making of any gait disorder. Although observational gait analysis is the therapist's primary clinical tool for describing the quality of a patient's walking pattern, it can be very unreliable. Modern gait analysis is facilitated through the use of specialized equipment. Currently, accurate gait analysis requires dedicated laboratories with complex settings and highly skilled operators. Wearable locomotion tracking systems are available, but they are not sufficiently accurate for clinical gait analysis. At the same time, wireless healthcare is evolving. Particularly, ultra wideband (UWB) is a promising technology that has the potential for accurate ranging and positioning in dense multi-path environments. Moreover, impulse-radio UWB (IR-UWB) is suitable for low-power and low-cost implementation, which makes it an attractive candidate for wearable, low-cost, and battery-powered health monitoring systems. The goal of this research is to propose and investigate a full-body wireless wearable human locomotion tracking system using UWB radios. Ultimately, the proposed system should be capable of distinguishing between normal and abnormal gait, making it suitable for accurate clinical gait analysis. / Ph. D.

yes / Multiple-input multiple-output (MIMO) antennas with four and eight elements having connected grounds are designed for ultra-wideband applications. Careful optimization of the lines connecting the grounds leads to reduced mutual coupling amongst the radiating patches. The proposed antenna has a modified substrate geometry and comprises a circular arc-shaped conductive element on the top with the modified ground plane geometry. Polarization diversity and isolation are achieved by replicating the elements orthogonally forming a plus shape antenna structure. The modified ground plane consists of an inverted L strip and semi ellipse slot over the partial ground that helps the antenna in achieving effective wide bandwidth spanning from (117.91%) 2.84–11 GHz. Both 4/8-port antenna achieves a size of 0.61 λ × 0.61 λ mm2 (lowest frequency) where 4-port antenna is printed on FR4 substrate. The 4-port UWB MIMO antenna attains wide impedance bandwidth, Omni-directional pattern, isolation >15 dB, ECC 4.5 dB making the MIMO antenna suitable for portable UWB applications. Four element antenna structure is further extended to 8-element configuration with the connected ground where the decent value of IBW, isolation, and ECC is achieved.

This doctoral thesis presents a comprehensive exploration of ultrawideband technology in addressing diverse challenges within localization systems. Beginning with the development of an innovative, cost-effective, and anonymous contact tracing solution for industrial environments during the COVID-19 pandemic, the research integrates ultra-wideband positioning, Bluetooth low-energy, and inertial measurement units. The subsequent sections delve into relative positioning systems, device-free localization, UWB bistatic radar sensors, and UAV-based tracking, showcasing novel methodologies and hardware implementations with promising outcomes. The work extends to groundbreaking approaches in deploying UWB infrastructure through self-deployable robots and cooperative positioning schemes using a UAV swarm. The contributions highlight versatility, costeffectiveness, and scalability, opening new possibilities for applications in security, logistics, IoT services, and space exploration. In summary, this thesis represents a significant advancement in localization systems, offering practical solutions and paving the way for future research and applications

Du fait de la nature ouverte et partagée du canal radio, les communications sans fil souffrent de vulnérabilités sérieuses en terme de sécurité. Dans ces travaux de thèse, je me suis intéressé particulièrement à deux classes d’attaques à savoir l’attaque par relais et l’attaque par déni de service (brouillage). La technologie de couche physique UWB-IR a connu un grand essor au cours de cette dernière décennie et elle est une candidate intéressante pour les réseaux sans fil à courte portée. Mon objectif principal était d’exploiter les caractéristiques de la couche physique UWB-IR afin de renforcer la sécurité des communications sans fil. L’attaque par relais peut mettre à défaut les protocoles cryptographiques d’authentification. Pour remédier à cette menace, les protocoles de distance bounding ont été proposés. Dans ce cadre, je propose deux nouveaux protocoles (STHCP : Secret Time-Hopping Code Protocol et SMCP : Secret Mapping Code Protocol) qui améliorent considérablement la sécurité des protocoles de distance bounding au moyen des paramètres de la radio UWB-IR. Le brouillage consiste en l’émission intentionnelle d’un signal sur le canal lors du déroulement d’une communication. Mes contributions concernant le problème de brouillage sont triples. D’abord, j’ai déterminé les paramètres d’un brouilleur gaussien pire cas contre un récepteur UWB-IR non-cohérent. En second lieu, je propose un nouveau modèle de brouillage par analogie avec les attaques contre le système de chiffrement. Troisièmement, je propose une modification rendant la radio UWB-IR plus robuste au brouillage. Enfin, dans une dernière partie de mes travaux, je me suis intéressé au problème d’intégrer la sécurité à un réseau UWB-IR en suivant l’approche d’embedding. Le principe de cette approche consiste à superposer et à transmettre les informations de sécurité simultanément avec les données et avec une contrainte de compatibilité. Ainsi, je propose deux nouvelles techniques d’embedding pour la couche physique UWB-IR afin d’intégrer un service d’authentification. / Due to the shared nature of wireless medium, wireless communications are more vulnerable to security threats. In my PhD work, I focused on two types of threats: relay attacks and jamming. UWB-IR physical layer technology has seen a great development during the last decade which makes it a promising candidate for short range wireless communications. My main goal was to exploit UWB-IR physical layer characteristics in order to reinforce security of wireless communications. By the simple way of signal relaying, the adversary can defeat wireless authentication protocols. The first countermeasure proposed to thwart these relay attacks was distance bounding protocol. The concept of distance bounding relies on the combination of two sides: an authentication cryptographic side and a distance checking side. In this context, I propose two new distance bounding protocols that significantly improve the security of existing distance bounding protocols by means of UWB-IR physical layer parameters. The first protocol called STHCP is based on using secret time-hopping codes. Whereas, the second called SMCP is based on secret mapping codes. Security analysis and comparison to the state of the art highlight various figures of merit of my proposition. Jamming consists in the emission of noise over the channel while communication is taking place and constitutes a major problem to the security of wireless communications. In a first contribution, I have determined worst case Gaussian noise parameters (central frequency and bandwidth) against UWB-IR communication employing PPM modulation and a non-coherent receiver. The metric considered for jammer optimization is the signal-to-jamming ratio at the output of the receiver. In a second contribution, I propose a new jamming model by analogy to attacks against ciphering algorithms. The new model leads to distinguish various jamming scenarios ranging from the best case to the worst case. Moreover, I propose a modification of the UWB-IR physical layer which allows to restrict any jamming problem to the most favorable scenario. The modification is based on using a cryptographic modulation depending on a stream cipher. The new radio has the advantage to combine the resistance to jamming and the protection from eavesdropping. Finally, I focused on the problem of security embedding on an existing UWB-IR network. Security embedding consists in adding security features directly at the physical layer and sending them concurrently with data. The embedding mechanism should satisfy a compatibility concern to existing receivers in the network. I propose two new embedding techniques which rely on the superposition of a pulse orthogonal to the original pulse by the form or by the position. Performances analysis reveal that both embedding techniques satisfy all system design constraints.

Ultra-wideband (UWB) radio techniques have long promised good contrast and high resolution for imaging human tissue and tumours; however, to date, this promise has not entirely been realised. In recent years, microwave imaging has been recognised as a promising non-ionising and non-invasive alternative screening technology, gaining its applicability to breast cancer by the significant contrast in the dielectric properties at microwave frequencies of normal and malignant tissues. This thesis deals with the development of two novel imaging methods based on UWB microwave signals. First, the mode-matching (MM) Bessel-functions-based algorithm, which enables the identification of the presence and location of significant scatterers inside cylindrically-shaped objects is introduced. Next, with the aim of investigating more general 3D problems, the Huygens principle (HP) based procedure is presented. Using HP to forward propagate the waves removes the need to apply matrix generation/inversion. Moreover, HP method provides better performance when compared to conventional time-domain approaches; specifically, the signal to clutter ratio reaches 8 dB, which matches the best figures that have been published. In addition to their simplicity, the two proposed methodologies permit the capture of a minimum dielectric contrast of 1:2, the extent to which different tissues, or differing conditions of tissues, can be discriminated in the final image. Moreover, UWB allows all the information in the frequency domain to be utilised, by combining information gathered from the individual frequencies to construct a consistent image with a resolution of approximately one quarter of the shortest wavelength in the dielectric medium. The power levels used and the specific absorption rates are well within safety limits, while the bandwidths satisfy the UWB definition of being at least 20% of the centre frequencies. It follows that the methodologies permit the detection and location of significant scatterers inside a volume. Validation of the techniques through both simulations and measurements have been performed and presented, illustrating the effectiveness of the methods.

Synthetic Aperture Radar (SAR) is an emerging technique in remote sensing. The technology is capable of producing high-resolution images of the earth surface in all-weather conditions. Thesis work describes the present available methods for positioning and imaging targets using M-sequence UWB (Ultra-Wideband) radar signals with moving antennas and SAR algorithm to retrieve position and image of the target. M-sequence UWB radar technology used as signal source for transmission and receiving echoes of target. Pseudo random binary sequence is used as a transmitted signal. These radars have an ability to penetrate signal through natural and unnatural objects. It offers low cost and quality security system. Among a number of techniques of image retrieval in Synthetic Aperture Radar, study of Global back projection (GBP) algorithm is presented. As a time domain algorithm, GBP possesses inherent advantages over frequency domain algorithm like ability to handle long integration angle, wider bandwidth and unlimited aperture size. GBP breaks the full synthesis aperture into numbers of sub-apertures. These sub-apertures are treated pixel by pixel. Each sub-aperture is converted to a Cartesian image grid to form an image.  During this conversion the signal is treated with linear interpolation methods in order to achieve the best quality of the images. The objective of this thesis is the imaging of target using M-sequence UWB radar and processing SAR raw data using Global back projection algorithm.

Ultra wide band (UWB) is an extremely promising wireless technology for researchers and industrials. One of the most interesting is its high data rate and fading robustness due to selective frequency fading. However, beside such advantages, UWB system performance is highly affected by existing narrowband interference (NBI), undesired UWB signals and tone/multi-tone noises. For this reason, research about NBI cancellation is still a challenge to improve the system performance vs. receiver complexity, power consumption, linearity, etc. In this work, the two major receiver sections, i.e., analog (radiofrequency or RF) and digital (digital signal processing or DSP), were considered and new techniques proposed to reduce circuit complexity and power consumption, while improving signal parameters. In the RF section, different multiband UWB low-noise amplifier key design parameters were investigated like circuit configuration, input matching and desired/undesired frequency band filtering, highlighting the most suitable filtering package for efficient UWB NBI cancellation. In the DSP section, due to pulse transmitter signals, different issues like modulation type and level, pulse variety, shape and color noise/tone noise assumptions, were addressed for efficient NBI cancelation. A comparison was performed in terms of bit-error rate, signal-to-interference ratio, signal-to-noise ratio, and channel capacity to highlight the most suitable parameters for efficient DSP design. The optimum number of filters that allows the filter bandwidth to be reduced by following the required low sampling rate and thus improving the system bit error rate was also investigated.

Near field imaging using microwave in medical applications has gain much attention recently as various researches show its high ability and accuracy in illuminating object comparing to the well-known screening tools such as Magnetic Resonance Imaging (MRI), digital mammography, ultrasound etc. This has encourage and motivate scientists continue to exploit the potential of microwave imaging so that a better and more powerful sensing tools can be developed. This thesis documents the development of antenna design for microwave imaging application such as breast cancer detection. The application is similar to the concept of Ground Penetrating Radar (GPR) but operating at higher frequency band. In these systems a short pulse is transmitted from an antenna to the medium and the backscattered response is investigated for diagnose. In order to accommodate such a short pulse, a very wideband antenna with a minimal internal reflection is required. Printed monopole and planar metal plate antenna is implemented to achieve the necessary operating wide bandwidth. The development of new compact printed planar metal plate ultra wide bandwidth antenna is presented. A generalized parametric study is carried out using two well-known software packages to achieve optimum antenna performance. The Prototype antennas are tested and analysed experimentally, in which a reasonable agreement was achieved with the simulations. The antennas present an excellent relative wide bandwidth of 67% with acceptable range of power gain between 3.5 to 7 dBi. A new compact size air-dielectric microstrip patch-antenna designs proposed for breast cancer detection are presented. The antennas consist of a radiating patch mounted on two vertical plates, fed by coaxial cable. The antennas show a wide bandwidth that were verified by the simulations and also confirmed experimentally. The prototype antennas show excellent performance in terms the input impedance and radiation performance over the target range bandwidth from 4 GHz to 8 GHz. A mono-static model with a homogeneous dielectric box having similar properties to human tissue is used to study the interaction of the antenna with tissue. The numerical results in terms the matching required of new optimised antennas were promising. An experimental setup of sensor array for early-stage breast-cancer detection is developed. The arrangement of two elements separated by short distance that confined equivalent medium of breast tissues were modelled and implemented. The operation performances due to several orientations of the antennas locations were performed to determine the sensitivity limits with and without small size equivalent cancer cells model. In addition, a resistively loaded bow tie antenna, intended for applications in breast cancer detection, is adaptively modified through modelling and genetic optimisation is presented. The required wideband operating characteristic is achieved through manipulating the resistive loading of the antenna structure, the number of wires, and their angular separation within the equivalent wire assembly. The results show an acceptable impedance bandwidth of 100.75 %, with a VSWR < 2, over the interval from 3.3 GHz to 10.0 GHz. Feasibility studies were made on the antenna sensitivity for operation in a tissue equivalent dielectric medium. The simulated and measured results are all in close agreement.

Le cadre de cette thèse est centré sur l'étude d'un radar ultra large bande (ULB) en mode impulsionnel, pour la « vision » à travers les murs (VAM), qui présente de nombreuses applications tant dans le domaine militaire (lors des assauts, des prises d’otages, …) que dans le secteur de la sécurité civile (recherche de personnes dans des décombres, dans un incendie, ...). Pour ces utilisations, l’image réelle de la scène observée n’est pas nécessaire, seules certaines informations pertinentes suffisent : nombre de personnes, position, vitesse de déplacement, etc. C'est dans ce contexte que nous avons développé un dispositif expérimental de détection et des techniques de localisation de cibles derrière un mur. Le radar développé est constitué d’un émetteur impulsionnel couvrant la gamme de fréquence de 3 GHz à 6 GHz, et de trois récepteurs indépendants, associés à des algorithmes de localisation et de reconstruction d'image.Le premier algorithme repose sur une technique de trilatération. Une fois, le modèle théorique présenté, plusieurs méthodes de résolution sont étudiées pour l'estimation de la mesure de la distance de propagation du signal. La méthode de Brent-Dekker a été retenue pour sa rapidité de convergence et son faible nombre d’itérations. Bien que cette technique soit précise, elle ne permet pas d’obtenir une image de la scène, mais juste de localiser les cibles, sans apporter des informations sur ses dimensions. C’est pourquoi une seconde approche, basée sur une « formation de faisceau », a été étudiée, afin d'obtenir une représentation 2D de la scène. Nous avons choisi de développer une méthode de rétroprojection non cohérente, technique la plus simple qui ne nécessite pas de contrainte forte sur la phase du signal ni sur le positionnement des antennes. Différentes variantes de rétroprojection ont été proposées : la rétroprojection avec cross corrélation, la rétroprojection cross corrélation améliorée et la rétroprojection bicross corrélée. Ces trois méthodes reposent sur une fusion d'informations capturées par l'antenne réceptrice avec celles obtenues sur des antennes dites de référence. Cette fusion a permis d'améliorer progressivement le rendu des images.Pour conclure ses travaux, une perspective est ébauchée afin de minimiser le taux de fausse détection, elle s'appuie sur la collaboration de la technique de trilatération avec la technique de rétroprojection bicross corrélée. Cette collaboration permet de mettre en correspondance les détections estimées par la technique de trilatération et celles utilisant la rétroprojection bicross corrélée. Les cibles non appariées sont alors supprimées selon des critères spécifiques à chacune des deux approches. / The content of this thesis is focused on the study of an UWB pulse radar for through the wall vision which has many applications in the military domain (assaults, hostage rescue,…) and in the civil security domain (people search in the rubble, in a fire).For these uses, the real observed scene image is not necessary, only some relevant information is enough: number of persons, position, velocity of movement, etc. It’s in this context where we have developed an experimental detection device and some through the wall targets localization techniques. The developed radar consists of a pulse transmitter covering the frequency range from 3GHz to 6GHz, and three independent receivers, combined with some localization algorithms and image reconstruction.The first algorithm is based on a technique of trilateration. Once the theoretical model is presented, many resolutions methods are studied for estimation of the signal propagation distance measurement. The Brent-Dekker method has been chosen for its fast convergence and low number of iterations. Although the trilateration technique is accurate, it does not allow obtaining a scene image, but just locate the targets, without providing their dimensions. Therefore a second approach, based on a “beam forming”, has been studied, in order to obtain a 2D scene representation. We have chosen to develop a non-coherent backprojection method, it is the most simple technique which does not require a strong constraint on the signal phase nor on the antenna positions. Different backprojection methods have been proposed: the backprojection with cross correlation, the improved backprojection with cross correlation and bi-cross correlated backprojection. These three methods are based on a fusion of captured information by the receiving antennas and with the obtained information on the “referenced” antennas. This fusion allows improving the image quality progressively.To conclude this work, a perspective is initiated in order to minimize the false detection rate, it is based on the cooperation of the trilateration technique and bi-cross correlated backprojection. This cooperation allows matching the estimated detection by the trilateration technique and the bi-cross correlated backprojection technique. The mismatched targets are removed according to some specific criterias to each approach.

La théorie de l'information développée par Claude Shannon (1916 - 2001) met en évidence le fait que pour accroître la capacité d'un canal de transmission, il est préférable d'élargir la bande de fréquences sur laquelle les informations sont émises plutôt que les puissances d'émissions. Cette constatation est le point de départ de nombreux travaux de recherche sur les communications Ultra-Large Bande (ULB) qui ont abouti en 2002 à la création aux Etats-Unis d'une bande fréquence dîtes ULB où aucun mode de communication n'est privilégié. C'est ainsi que 2 années plus tard ont débuté à l'IM2NP des travaux portant sur les communications ULB impulsionnelles, et notamment la conception d'amplificateur faible bruit, de détecteur d'énergie, mais également de générateurs d'impulsions qui est l'élément clé des émetteurs impulsionnels. Ces derniers constituent la base des travaux présentés dans le manuscrit qui se sont déroulés de 2008 à 2011. La nature discontinue des communications impulsionnelles a tout d'abord impliquée l'introduction de nouvelles figures de mérite permettant de mesurer les performances des générateurs d'impulsions. Ensuite, il est question de méthodes de conception permettant de dimensionner des structures fonctionnant aux fréquences en jeu mais également d'en réduire les consommations statiques principalement de fuite, et ce en vue de répondre aux contraintes de consommation des systèmes embarqués. Enfin sont développées 3 architectures de générateurs d'impulsions, chacune permettant de répondre à des contraintes différentes en termes de bande de fréquences, de consommation et de portée. / The information theory developed by Claude Shannon (1916 - 2001) highlights the fact that in order to increase the capacity of a transmission channel, it is preferable to extend the bandwidth used rather than the transmission power. This finding is the starting point of many papers on Ultra-Wideband (UWB) which led to the creation in the United States of UWB band since 2002 where no modulation is privileged. Two years later, many works on Impulsionnal Radio UWB (IR-UWB) communications began at IM2NP including the design of low noise amplifier, power detector, but also pulse generators which is the key element of IR-UWB emitters. These form basis of works presented in the manuscript that took place from 2008 to 2011. The discontinuous nature of communications impulse was first implied the introduction of new figures of merit for measuring performances of pulse generators. Then it deals with design techniques for sizing structures operating at frequencies involved, but also to reduce consumption and especially static leakage to reduce enough power consumption for embedded systems. Finally three architectures of pulse generators are developed, each one responding to different constraints in terms of frequency, consumption and range.