<p>Ultra wideband (UWB) communication systems refers to systems whose bandwidth is many times greater than the “narrowband” systems (refers to a signal which occupies only small amount of space on the radio spectrum). UWB can be used for indoor, communications for high data rates, or very low data rates for substantial link distances because of the extremely large bandwidth, immune to multi-path fading, penetrations through concrete block or obstacles. UWB can also used for short distance ranging whose applications include asset location in a warehouse, position location for wireless sensor networks, and collision avoidance.</p><p>In order to verify analytical and simulation results with real-world measurements, the need for experimental UWB systems arises. The Institute of Communications Engineering [IANT] has developed a low-cost experimental UWB positioning system to test UWB based positioning concepts. The mobile devices use the avalanche effect of transistors for simple generation of bi-phase pulses and are TDMA multi-user capable. The receiver is implemented in software and employs coherent cross-correlation with peak detection to localize the mobile unit via Time-Difference-Of-Arrival (TDOA) algorithms. Since the power of a proposed UWB system’s signal spread over a very wide bandwidth, the frequencies allocated to multiple existing narrowband systems may interfere with UWB spectrum. The goal of the filters discussed in this project is to cancel or suppress the interference while not distort the desired signal. To investigate the interference, we develop a algorithm to calculate the interference tones. In this thesis, we assume the interference to be narrowband interference (NBI) modeled as sinusoidal tones with unknown amplitude, frequency and phase. If we known the interference tones then it may be removed using a simple notched filter. Herein, we chose an adaptive filter so that it can adjust the interference tone automatically and cancel. In this thesis I tested adaptive filter technique to cancel interference cancellation (ie) LMS algorithm and Adaptive Noise Cancellation (ANC) technique. In this thesis performance of the both filters are compared.</p>

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

In recent years, ultra-wideband (UWB) communications has gained tremendous popularity in both research community and industry. The large bandwidth of UWB systems raises new wireless channel effects and consequently unique advantages as well as challenges to be dealt with, compared to conventional wireless systems. One of these advantages is the ability to resolve dense multipath components and use Rake combining at the receiver in order to significantly reduce the negative effects of fading. However, implementing a Rake receiver with a sufficiently large number of fingers to make use of this advantage is an evident challenge for most UWB devices with limited signal processing capabilities. A possible approach to overcome this problem is to move computational complexity from the receiver to the more powerful transmitter, which is the main focus of the present work. In this thesis, we propose two novel pre-equalization schemes for multiple- input single-output (MISO) direct-sequence ultra-wideband (DS-UWB) systems with pre-Rake combining and symbol-by-symbol detection. The first pre-equalization filter (PEF) scheme employs one PEF per transmit antenna, whereas in the second, simplified PEF (S-PEF) scheme all transmit antennas share the same PEF. For both schemes the optimum finite impulse response (FIR) and infinite impulse response (IIR) PEFs are calculated based on the minimum mean squared error (MMSE) criterion. We show that in contrast to previously proposed schemes for DS-UWB, both our proposed PEF schemes efficiently exploit the channel shortening properties of the pre-Rake filter. In particular, our proposed PEF schemes operate at the symbol level. We also show that under certain conditions the S-PEF scheme achieves the same performance as the more complex PEF scheme. Finally, we demonstrate that a single-input multiple-output (SIMO) DS-UWB system with post-Rake combining and MMSE post-equalization is the dual system to the considered MISO DS–UWB system with pre-Rake combining and MMSE pre-equalization. This uplink-downlink duality can be exploited for efficient calculation of the PEFs and for complexity reduction. Our simulation results show that the proposed PEF schemes achieve significant performance gains over pre-Rake combining without equalization even if only short PEFs are employed, and this is the case even for long UWB channel impulse responses.

Ultra wideband (UWB) communication systems refers to systems whose bandwidth is many times greater than the “narrowband” systems (refers to a signal which occupies only small amount of space on the radio spectrum). UWB can be used for indoor, communications for high data rates, or very low data rates for substantial link distances because of the extremely large bandwidth, immune to multi-path fading, penetrations through concrete block or obstacles. UWB can also used for short distance ranging whose applications include asset location in a warehouse, position location for wireless sensor networks, and collision avoidance. In order to verify analytical and simulation results with real-world measurements, the need for experimental UWB systems arises. The Institute of Communications Engineering [IANT] has developed a low-cost experimental UWB positioning system to test UWB based positioning concepts. The mobile devices use the avalanche effect of transistors for simple generation of bi-phase pulses and are TDMA multi-user capable. The receiver is implemented in software and employs coherent cross-correlation with peak detection to localize the mobile unit via Time-Difference-Of-Arrival (TDOA) algorithms. Since the power of a proposed UWB system’s signal spread over a very wide bandwidth, the frequencies allocated to multiple existing narrowband systems may interfere with UWB spectrum. The goal of the filters discussed in this project is to cancel or suppress the interference while not distort the desired signal. To investigate the interference, we develop a algorithm to calculate the interference tones. In this thesis, we assume the interference to be narrowband interference (NBI) modeled as sinusoidal tones with unknown amplitude, frequency and phase. If we known the interference tones then it may be removed using a simple notched filter. Herein, we chose an adaptive filter so that it can adjust the interference tone automatically and cancel. In this thesis I tested adaptive filter technique to cancel interference cancellation (ie) LMS algorithm and Adaptive Noise Cancellation (ANC) technique. In this thesis performance of the both filters are compared.

Closed loop fuel injection have been in use for two decades but it's not until the recent five years that the wide band lambda sensor have been utilized. The goal is to explain wide band and discrete lambda sensors in a simple but powerful way. Both sensors are modeled by simple mathematics and accounts for Oxygen, Hydrogen and Carbon monoxide influences. The focus is not just on the output from the sensors, but also on the underlying function. This means that all explanations are thorough and methodical. The function of a wide band lambda sensor is more complicated than a discrete type lambda sensor, therefore it's harder to get correct readings. The model of the wide band lambda sensor is used to evaluate different problems in preparation for the development of an observer. Several potential problem sources are tested and investigated, these include calibration error, pressure error, air leak error, gas sensitivity and fuel errors. To evaluate the potential problems and their ability to explain differences between actual lambda and sensor output, two sensors with differing outputs have been used. The final result is implemented in an ECU. The models indicate that the difference between the two sensors is most likely explained by different sensitivity for CO, O2 and H2. This can in turn have one or several explanations. It is suggested that different ability to pump oxygen, different nernst cells or even different controllers can cause this. The reason is not investigated further as this would require a very deep research on the two sensors. Because no usable explanation is found an observer that estimates the offset at stoichiometric conditions, where lambda equals one, is constructed. The observer uses the fact that the switch point of a discrete lambda sensor is insensitive to disturbances. The offset calculation is performed in real time on an ECU. Tools for calibration of the observer are also developed. With the observer the error for the two sensors is roughly halved over the whole spectrum and at stoichiometric conditions, which is the normal operation for an engine, the error was too small to measure. Although the wide band lambda sensor is a very complex sensor it is shown that it can be understood with simple mathematics and basic knowledge in chemistry. The developed model agrees well with the real sensor for steady state conditions. For transient conditions, however, the model needs to be refined further. The question why the two sensors differ is discussed but the true origin of the cause remains unsolved. The conclusion is that the error can be drastically reduced with just an offset. It is also shown that when building a lambda sensing device the controller is of equal importance as the sensor element itself. This is due to the sensitivity of surrounding factors that the controller must be able to handle. These effects are specially important for engines running at lambda not equal to 1, for example diesel engines.

Sensor arrays are used in many applications where their ability to localize signal sources is essential. For many applications, it is necessary to estimate the direction-of-arrival (DOA) of target sources. Although there are many DOA estimation methods available, most of them are valid only for narrowband signals where time delay can be approximated as a phase shift. This thesis focuses on DOA estimation algorithms for wideband sources. Specifically, this thesis proposes the pruned fast beamformer which can reduce the number of computations of Delay-and-Sum (DS) beamforming by using a multi-resolution structure. For high resolution methods, signal subspace methods are required. Most of the subspace techniques for wideband signals decompose the received wideband signals into several bands of narrowband signals through bandpass filtering. Then, there are two different ways of processing decomposed signals. The incoherent methods process each band independently by a given narrowband method and average the results. The coherent methods attempt to modulate the signals in each band so that they can be combined coherently. In this thesis, a new DOA estimator, which is called TOPS, is developed to avoid disadvantages of both the incoherent and the coherent methods. The new method which can be categorized as a non-coherent method is tested and compared with other methods. It exhibits many desirable features for a number of applications where the sources are wideband such as acoustic direction finding.

This dissertation presents a wide-band lumped element equivalent circuit model and a building block-based scalable circuit model for multiple quantum well laser diodes. The wide-band multiple-resonance model expresses two important laser diode characteristics such as input reflection and electrical-to-optical transmission together. Additionally, it demonstrates good agreements with the measurement results of the selected commercial discrete laser diodes. The proposed building block-based modeling approach proves its validity using a numerically derived scalable rate equation. Since success in a circuit design depends largely on the availability of accurate device models, the practical application of the proposed models provides improved accuracy, simple implementation and a short design time.

The thesis uses an up-down conversion architecture to realize a wideband frequency synthesizer for digital video broadcasting (DVB) transmission system. At first, the theoretical analysis of this architecture is performed to understand the mechanism to suppress the phase noise in an optimal way. Then, the simulations using Matlab and ADS are carried out to predict the phase noise performance. Based on the above efforts, a 50 MHz ~ 1 GHz wideband frequency synthesizer hybrid circuit is implemented and its phase noise performance, corresponding to different choices of the reference sources, is finally discussed. The second part of this thesis is to extend the up-down conversion architecture to an offset phase-locked loop (PLL) architecture for wideband frequency synthesizers. The difference from the conventional offset PLLs is the phase locking of the signal at either the sum or the difference frequency of two voltage-controlled oscillators (VCOs) to the reference source for the purpose of wideband operation. The phase noise analysis of the proposed offset PLL architecture is provided. In the experiments, a 300 MHz ~ 3.6 GHz wideband frequency synthesizer hybrid circuit is implemented to verify the analyzed phase noise results. In addition, a CMOS wideband frequency synthesizer chip using the proposed offset PLL architecture has been realized. Moreover, another two CMOS wideband frequency synthesizer chips are included in this thesis. It is worth mentioning that the VCOs in these two frequency synthesizer chips use the switched capacitor and inductor techniques to achieve a wideband operation.

As the microwave wireless communication systems growing rapidly, microstrip planar ceramic filters attract many attentions because of the advantages of small size, low cost, easy fabrication, higher performance and easy integration. In this thesis, several kinds of bandpass filters are designed for different operating purposes. First, two kinds of dual-mode bandpass filters are designed for 2.4 GHz wideband with the T-shaped I/O arranging in a straight way for easy integration. Second, the hook-coupling and insert-coupling structures are adopted for series connecting of the stepped-impedance resonator structures, and 2.4/5.2 GHz dual-band filtering properties could be achieved. Third, two open-loop rectangular ring resonators and U-shaped I/O are designed for 2.4/5.2 GHz dual-band bandpass filters with deep transmission zeros. The quarter wavelength stubs and groove structures are used for enhancing deep transmission zeros between two passband and ripples of the second passband, respectively. Fourth, the parallel positioned resonators with phase difference method are used to design the dual-band (1.23/2.4 GHz) and quad-band (1.23/2.4/3.5/5.2 GHz) bandpass filter with asymmetrical bandwidths and transmission zeros. In the thesis, high quality Al2O3 ceramic substrates are used to fabricate different kinds of bandpass filters for pattern minimization and low losses. The electromagnetic simulators, HFSS and IE3D, were used to adjust and optimize the associated parameters. The printing method was used to fabricate the proposed bandpass filters, which did not need using the FeCl3 to etch the Cu plate from the surface of Duroid or the FR4 substrates. The proposed filters are measured by Agilent-N5230A with the SMA connectors welding. Finally, the simulated and measured results of proposed bandpass filters are in good agreement.

The thesis is mainly focused on a hybrid location system, which processes wireless and inertial measurements by extended Kalman filtering. Inertial location system is usually used with Dead-Reckoning method, which calculates the present location and heading direction from a previous known state by using measurements of accelerometer and gyroscope, which have immunity from the environment. The system estimates the position by integrates the measurements of sensors, resulting in high accuracy during a short period. However, the unreliability grows with time due to the bias effect on sensors. By combining the wireless location and inertial system, the uncertainty of estimation can be reduced. In wireless communications, the locations of base stations and the times of signal arrival can be used in locating a mobile station. However, signal propagation could be blocked by objects. The non-line of sight (NLOS) effects cause arrival delay and is usually modeled as exponential distributions. Previously, the improved biased Kalman filters were designed to mitigate the NLOS effect in base station measurements. The system design has difficulty in accommodating inertial measurements. The inertial has immunity to the environment. The property is of help in the NLOS mitigation. Therefore, we propose a hybrid location system that integrating the wireless and inertial measurements by using a hybrid biased extended Kalman filter at the stage of positioning. The system provides better prediction with the assistance of enviroment-free inertial measurements. The NLOS mitigation with prediction feedback scheme results in better mitigation performance. Simulations of different situations have been conducted based on parameters in the IEEE 802.15.3a ultra-wideband environment. The performance differences between the proposed method and other approaches show that inertial assisted system effectively reduces the NLOS effects. Also, the proposed hybrid location system has more efficient mitigation performance and better tracking results.