Optimal Waveforms Design for Ultra-Wideband Impulse Radio Sensors

Ultra-wideband impulse radio (UWB-IR) sensors should comply entirely with the regulatory spectral limits for elegant coexistence. Under this premise, it is desirable for UWB pulses to improve frequency utilization to guarantee the transmission reliability. Meanwhile, orthogonal waveform division multiple-access (WDMA) is significant to mitigate mutual interferences in UWB sensor networks. Motivated by the considerations, we suggest in this paper a low complexity pulse forming technique, and its efficient implementation on DSP is investigated. The UWB pulse is derived preliminarily with the objective of minimizing the mean square error (MSE) between designed power spectrum density (PSD) and the emission mask. Subsequently, this pulse is iteratively modified until its PSD completely conforms to spectral constraints. The orthogonal restriction is then analyzed and different algorithms have been presented. Simulation demonstrates that our technique can produce UWB waveforms with frequency utilization far surpassing the other existing signals under arbitrary spectral mask conditions. Compared to other orthogonality design schemes, the designed pulses can maintain mutual orthogonality without any penalty on frequency utilization, and hence, are much superior in a WDMA network, especially with synchronization deviations

An Analysis of Electromagnetic Interference (EMI) of Ultra Wideband(UWB) and IEEE 802.11A Wireless Local Area Network (WLAN) Employing Orthogonal Frequency Division Multiplexing (OFDM)

Military communications require the rapid deployment of mobile, high-bandwidth systems. These systems must provide anytime, anywhere capabilities with minimal interference to existing military, private, and commercial communications. Ultra Wideband (UWB) technology is being advanced as the next generation radio technology and has the potential to revolutionize indoor wireless communications. The ability of UWB to mitigate multipath fading, provide high-throughput data rates (e.g., greater than 100 Mbps), provide excellent signal penetration (e.g., through walls), and low implementation costs makes it an ideal technology for a wide range of private and public sector applications. Preliminary UWB studies conducted by The Institute for Telecommunications Science (ITS) and the Defense Advanced Research Projects Agency (DARPA) have discovered that potential exists for harmful interference to occur. While these studies have provided initial performance estimates, the interference effects of UWB transmissions on coexisting spectral users are largely unknown. This research characterizes the electromagnetic interference (EMI) effects of UWB on the throughput performance of an IEEE 802.11a ad-hoc network. Radiated measurements in an anechoic chamber investigate interference performance using three modulation schemes (BPSK, BPPM, and OOK) and four pulse repetition frequencies over two Unlicensed National Information Infrastructure (U-NII) channels. Results indicate that OOK and BPPM can degrade throughput performance by up to 20% at lower pulse repetition frequencies (PRFs) in lower U-NII channels. Minimal performance degradation (less than one percent) due to interference was observed for BPSK at the lower PRFs and higher U-NII channels

Study of Optical OFDM System for Wireless LAN Applications

The advantages of optical fiber make it possible to extend the data rate transmission and propagation distance. Orthogonal frequency division multiplexing (OFDM) as a multicarrier technique (MC) is used in hybrid optical-wireless system designs because it has the best spectral efficiency to radio frequency (RF) interference and lower multipath distortion. In this dissertation, a study and evaluation of optical OFDM based wireless local area network (W-LAN) systems are presented. The baseband of the OFDM signal is fully transmitted and up-converted to a radio frequency signal. Also, to reduce system costs, simple base stations (BSs) are interconnected to a central office (CO) via an optical fiber. All the required operations are achieved in the CO. The directly modulated laser (DML) and continuous wave (CW) laser are used in the system simulations as optical laser sources. Identical rectangular microstrip patch antennas have been used at the transmitter and the receiver as well. The simulations were carried out for different SMF and MMF lengths, and the variable wireless distance between the transmitting and receiving antennas was in a range of 40 dB to 80 dB. The purpose of this work is to provide a framework for integrating wireless and optical technologies in one system with the presence of OFDM technology. The required microstrip patch antenna parameters for the system are analyzed and designed. The microstrip patch antenna (S-parameters) is loaded into the Optisystem communication software tool in Touchstone format. As a result, this achievement gives a greater impetus to design an integrated optical-wireless system, and simulation results validate the proposed technique. Then, the integration of the microstrip patch antenna and optical OFDM system is achieved, and the performance is intensely studied. The entire system has been presented by developing analytical models and simulations. The system performance results are obtained regarding EIRP, SNR, signal constellations and BER. The results show that this integrated optical wireless link is very robust for carrying OFDM based wireless LAN signals over an optical fiber. Moreover, using an active patch antenna in the system helps to increase the coverage service to more than 30 meters when an SMF of 80 km length is utilized

Ultra-wideband indoor communications using optical technology

La communication ultra large bande (UWB) a attiré une énorme quantité de recherches ces dernières années, surtout après la présentation du masque spectral de US Federal Communications Commission (FCC). Les impulsions ultra-courtes permettent de très hauts débits de faible puissance tout en éliminant les interférences avec les systèmes existants à bande étroite. La faible puissance, cependant, limite la portée de propagation des radios UWB à quelques mètres pour la transmission sans fil à l’intérieur d’une pièce. En outre, des signaux UWB reçu sont étendus dans le temps en raison de la propagation par trajet multiple qui résulte en beaucoup d’interférence inter-symbole (ISI) à haut débit. Le monocycle Gaussien, l’impulsion la plus commune dans UWB, a une mauvaise couverture sous le masque de la FCC. Dans cette thèse, nous démontrons des transmet- teurs qui sont capables de générer des impulsions UWB avec une efficacité de puissance élevée. Une impulsion efficace résulte dans un rapport de signal à bruit (SNR) supérieur au récepteur en utilisant plus de la puissance disponible sous le masque spectral de la FCC. On produit les impulsions dans le domaine optique et utilise la fibre optique pour les transporter sur plusieurs kilomètres pour la distribution dans un réseau optique pas- sif. La fibre optique est très fiable pour le transport des signaux radio avec une faible consommation de puissance. On utilise les éléments simples comme un modulateur Mach-Zehnder ou un résonateur en anneau pour générer des impulsions, ce qui permet l’intégration dans le silicium. Compatible avec la technologie CMOS, la photonique sur silicium a un potentiel énorme pour abaisser le coût et l’encombrement des systèmes optiques. La photodétection convertit les impulsions optiques en impulsions électriques avant la transmission sur l’antenne du côté de l’utilisateur. La réponse fréquentielle de l’antenne déforme la forme d’onde de l’impulsion UWB. Nous proposons une technique d’optimisation non-linéaire qui prend en compte la distorsion d’antenne pour trouver des impulsions qui maximisent la puissance transmise, en respectant le masque spectral de la FCC. Nous travaillons avec trois antennes et concevons une impulsion unique pour chacune d’entre elle. L’amélioration de l’énergie des impulsions UWB améliore directement la SNR au récepteur. Les résultats de simulation montrent que les impulsions optimisées améliorent considérablement le taux d’erreur (BER) par rapport au monocycle Gaussien sous propagation par trajet multiple. Notre autre contribution est l’évaluation d’un filtre adapté pour recevoir efficacement des impulsions UWB. Le filtre adapté est synthétisé et fabriqué en technologie microstrip, en collaboration avec l’Université McGill comme un dispositif de bande interdite électromagnétique. La réponse fréquentielle du filtre adapté montre une ex- cellente concordance avec le spectre ciblé de l’impulsion UWB. Les mesures de BER confirment la performance supérieure du filtre adapté par rapport à un récepteur à conversion directe. Le canal UWB est très riche en trajet multiple conduisant à l’ISI à haut débit. Notre dernière contribution est l’étude de performance des récepteurs en simulant un système avec des conditions de canaux réalistes. Les résultats de la simulation montrent que la performance d’un tel système se dégrade de façon significative pour les hauts débits. Afin de compenser la forte ISI dans les taux de transfert de données en Gb/s, nous étudions l’algorithme de Viterbi (VA) avec un nombre limité d’états et un égaliseur DFE (decision feedback equalizer). Nous examinons le nombre d’états requis dans le VA, et le nombre de coefficients du filtre dans le DFE pour une transmission fiable de UWB en Gb/s dans les canaux en ligne de vue. L’évaluation par simulation de BER confirme que l’égalisation améliore considérablement les performances par rapport à la détection de symbole. La DFE a une meilleure performance par rapport à la VA en utilisant une complexité comparable. La DFE peut couvrir une plus grande mémoire de canal avec un niveau de complexité relativement réduit.Ultra-wideband (UWB) communication has attracted an enormous amount of research in recent years, especially after the introduction of the US Federal Communications Commission (FCC) spectral mask. Ultra-short pulses allow for very high bit-rates while low power eliminates interference with existing narrowband systems. Low power, however, limits the propagation range of UWB radios to a few meters for indoors wireless transmission. Furthermore, received UWB signals are spread in time because of multipath propagation which results in high intersymbol interference at high data rates. Gaussian monocycle, the most commonly employed UWB pulse, has poor coverage under the FCC mask. In this thesis we demonstrate transmitters capable of generating UWB pulses with high power efficiency at Gb/s bit-rates. An efficient pulse results in higher signal-to-noise ratio (SNR) at the receiver by utilizing most of the available power under the FCC spectral mask. We generate the pulses in the optical domain and use optical fiber to transport the pulses over several kilometers for distribution in a passive optical network. Optical fiber is very reliable for transporting radio signals with low power consumption. We use simple elements such as a Mach Zehnder modulator or a ring resonator for pulse shaping, allowing for integration in silicon. Being compatible with CMOS technology, silicon photonics has huge potential for lowering the cost and bulkiness of optical systems. Photodetection converts the pulses to the electrical domain before antenna transmission at the user side. The frequency response of UWB antennas distorts the UWB waveforms. We pro- pose a nonlinear optimization technique which takes into account antenna distortion to find pulses that maximize the transmitted power, while respecting the FCC spectral mask. We consider three antennas and design a unique pulse for each. The energy improvement in UWB pulses directly improves the receiver SNR. Simulation results show that optimized pulses have a significant bit error rate (BER) performance improvement compared to the Gaussian monocycle under multipath propagation. Our other contribution is evaluating a matched filter to receive efficiently designed UWB pulses. The matched filter is synthesized and fabricated in microstrip technology in collaboration with McGill University as an electromagnetic bandgap device. The frequency response of the matched filter shows close agreement with the target UWB pulse spectrum. BER measurements confirm superior performance of the matched filter compared to a direct conversion receiver. The UWB channel is very rich in multipath leading to ISI at high bit rates. Our last contribution is investigating the performance of receivers by simulating a system employing realistic channel conditions. Simulation results show that the performance of such system degrades significantly for high data rates. To compensate the severe ISI at gigabit rates, we investigate the Viterbi algorithm (VA) with a limited number of states and the decision feedback equalizer (DFE). We examine the required number of states in the VA, and the number of taps in the DFE for reliable Gb/s UWB trans- mission for line-of-sight channels. Non-line-of-sight channels were also investigated at lower speeds. BER simulations confirm that equalization considerably improves the performance compared to symbol detection. The DFE results in better performance compared to the VA when using comparable complexity as the DFE can cover greater channel memory with a relatively low complexity level

Impulse radio ultra wideband over fiber techniques for broadband in-building network applications

In recent years, the demand for high bandwidth and mobility from the end users has been continuously growing. To satisfy this demand, broadband communication technologies that combined the benefit of both wired and wireless are considered as vital solutions. These hybrid optical wireless solutions enable multi-Gbit/s transmission as well as adequate flexibility in terms of mobility. Optical fiber is the ideal medium for such hybrid solution due its signal transparency and wide bandwidth. On the other hand, ultra wideband(UWB) radio over optical fiber technology is considered to be one of the key promising technologies for broadband communication and sensor network applications. The growing interest for UWB is mainly due to its numerous attractive features, such as low power spectral density, tolerance to multipath fading, low probability of interception, coexistence with other wireless services and capability of providing cost-effective > 1 Gb/s transmission. The main idea of UWB over fiber is to deliver UWB radio signals over optical channels, where the optical part serves as a backbone communication infrastructure to carry the UWB signal with a bandwidth of several GHz. This enables multiple novel applications such as: range extension of high speed wireless personal area networks (WPANs), low cost distributed antenna systems, secure and intelligent networks, or delivering broadband services to remote areas. In particular, this thesis deals with novel concepts on shaping and generation of IR-UWB pulses, theoretical and experimental demonstrations over different fiber types, routing of integrated wired/wireless IR-UWB services and effect of fiber types on ranging/localization of IR-UWB-over-fiber systems. Accordingly, this thesis investigates techniques for delivery of high data rate wireless services using impulse radio ultra wideband (IR-UWB) over fiber technology for both access and in-building network applications. To effectively utilize the emission mask imposed for UWB technologies by the Federal Communications Commission(FCC), novel pulse shaping techniques have been investigated and experimentally demonstrated. Comparison of the proposed pulses with conventional ones in terms of the compliance to the FCC-mask requirements, spectral power efficiencies and wireless coverage has been theoretically studied. Simple and efficient optical generation of the new pulse has been experimentally demonstrated. Furthermore, performance evaluation of 2 Gb/s transmission of IR-UWB over different types of fiber such as 25 km silica single-mode, 4.4 km silica multi-mode and 100 m plastic heavily-multi-mode fiber have been performed. To improve the functionalities of in-building networks for the delivery of wireless services; techniques that provide flexibility in terms of dynamic capacity allocation have been investigated. By employing wavelength conversion based on cross-gain modulation in optical semiconductor amplifiers(SOA), routing of three optical channels of IR-UWB over fiber system has been experimentally realized. To reduce the cost of the overall system and share the optical infrastructure, an integrated testbed for wired baseband data and wireless IR-UWB over 1 km SMF-28 fiber has been developed. Accordingly, 1.25 Gb/s wired baseband and 2 Gb/s wireless IR-UWB data have been successfully transmitted over the testbed. Furthermore, to improve the network flexibility, routing of both wired baseband and wireless signals has been demonstrated. Additionally, the ranging and localization capability of IR-UWB over fiber for in-door wireless picocells have been investigated. The effect of different fiber types (4 km SMF, 4.4 km GI-MMF and 100 m PF GI-POF) on the accuracy of the range estimation using time-of-arrival (ToA) ranging technique has been studied. A high accuracy in terms of cm level was achieved due to the combined effect of high bandwidth IR-UWB pulses, short reach fiber and low chromatic dispersion at 1300nm wavelength. Furthermore, ranging/ localization using IR-UWB over fiber system provides additional benefit of centralizing complex processing algorithms, simplifying radio access points, relaxing synchronization requirement, enabling energy-efficient and efficient traffic management networks. All the concepts, design and system experiments presented in this thesis underline the strong potential of IR-UWB for over optical fiber(silica and plastic) techniques for future smart, capacity and energy-efficient broadband in-building network applications

Ultra Wideband Preliminaries

Non

Design and Implementation of a UWB Radar Sensor for Non-Destructive Application

[ES] Debido a la importancia de los campos de aplicación del sensor de radar de banda ultraancha, y también a los requisitos de cada aplicación específica, existe una demanda creciente de diseño compacto, de bajo coste y alta precisión del sensor de radar de banda ultraancha. Para responder a estas exigencias, esta tesis pretende proponer un sensor de radar UWB avanzado. Este trabajo de investigación se centra en el diseño del sensor de radar de banda ultraancha (UWB) para aplicaciones no destructivas (END). Los detalles de diseño incluyen el diseño de un generador de pulsos ultracorto, de alta potencia con un timbre mínimo. El radar desarrollado fue construido con una configuración biestática. El objetivo de este trabajo es medir el rango de distancia y las propiedades eléctricas de un objetivo, por ejemplo, metales y materiales dieléctricos, como el cloruro de polivinilo (PV C). Para lograr este objetivo, se ha desarrollado un novedoso generador de pulsos de alta potencia ultra-corto (pulsador de radar). El nuevo generador de pulsos consiste en un transistor que funciona en modo de avalancha y un circuito de afilado de pulsos que utiliza un nuevo modelo de diodo de recuperación de paso (SRD). Para convertir el pulso gaussiano en un monociclo, se ha añadido una red de formación de monociclo (MFN). El generador de impulsos desarrollado produce un impulso eléctrico con una amplitud de 12 V, un tiempo de subida de 112 ps y un ancho de impulso (FWHM) de 155 ps. Con el fin de aumentar la amplitud de los pulsos, se han propuesto dos técnicas útiles en este trabajo. El primero consiste en agregar dos generadores en paralelo, en este diseño propuesto se tuvo en cuenta alguna especificación para hacer que este circuito funcione. Sin embargo, la segunda técnica adoptada en este trabajo consiste en dos etapas de generadores, ambas técnicas dan lugar a un buen rendimiento; en lugar de un solo módulo de un generador de impulsos, las técnicas propuestas en este trabajo aumentan la amplitud en torno al doble. Ambas técnicas han sido investigadas en detalle. Para transmitir y recibir los impulsos ultracortos generados, se utilizaron dos tipos diferentes de antenas UWB. En primer lugar, una antena Vivaldi con un ancho de banda de unos 5,5 GHz de 600 MHz a 6 GHz. La segunda es una antena Vivaldi con un ancho de banda de 6 GHz de 400 Mhz a 6,2 GHz. Utilizando el sensor de radar de banda ultraancha desarrollado, se realizaron mediciones de prueba. Esto incluye las propiedades eléctricas, así como la medición de la distancia a las placas de metal, madera y PVC. La incertidumbre del sensor de radar es de 14 mm (datos medidos asustados a + 14 mm para un blanco fijo). El diseño y la implementación real que conduce a lograr un excelente prototipo de rendimiento para una aplicación no destructiva.[CA] A causa de la rellevància dels camps d'aplicació del sensor de radar d'ultra banda ampla, i també l'exigència de cada aplicació específica, hi ha una demanda creixent de disseny compacte, de baix cost i alta precisió del sensor de radar d'ultra banda ampla. Amb la intenció d'atendre aquestes demandes, aquesta tesi pretén proposar un sensor avançat de radar UWB. Aquest treball de recerca tracta del disseny del sensor de radar d'ultra-banda ampla (UWB) per a aplicacions no destructives (NDT). Els detalls del disseny inclouen el disseny d'un pols de monocicle amb pols de potència d'alta potència i amb un mínim de timbre. El radar desenvolupat va ser construït en configuració bi-estàtica. L'objectiu d'aquest treball és mesurar el rang de distància i les propietats elèctriques d'un objectiu, per exemple, materials metàl·lics i dielèctrics, com el clorur de polivinil (PV C). Per assolir aquest objectiu, s'ha desenvolupat un nou ultrasò, generador de pols d'alta potència (polsador de radar). El nou generador de pols està format per un transistor que funciona en mode d'allaus i un circuit d'afilat de pols mitjançant un nou model de díode de recuperació de pas (SRD). Per a convertir el pols gaussiano en un monocicle, s'ha afegit una xarxa de formació de monocicles (MFN). El generador de polsos desenvolupat produeix un pols elèctric amb una amplitud de 12 V, un temps d'augment de 112 ps i un ample de pols (FWHM) de 155 ps. Amb l'objectiu d'augmentar l'amplitud dels polsos, s'han proposat dues tècniques útils en aquest treball. El primer consisteix a afegir dos generadors de forma paral·lela, en aquest disseny proposat, cal tenir en compte algunes especificacions per a fer la viabilitat d'aquest circuit. No obstant això, la segona tècnica adoptada en aquest treball consisteix en una doble etapa de generadors, ambdues tècniques donen lloc a una bona actuació; en lloc d'un únic mòdul d'un generador de pols, les tècniques proposades en aquest treball augmenten l'amplitud al voltant del doble. Per transmetre i rebre polsos ultra-curts generats, s'han utilitzat dos tipus diferents d'antenes UWB. En primer lloc, una antena de Vivaldi amb un ample de banda d'uns 5,5 GHz de 600 MHz a 6 GHz. Mentre que la segona és una antena Vivaldi amb un ample de banda de 6 GHz de 400 MHz a 6.2 GHz. Mitjançant el sensor de radar ultra-ampla desenvolupat, es va realitzar la mesura de la prova. Incloïen propietats elèctriques i mesures de distància a les plaques metàl·liques, fusta i PVC. S'ha trobat que la incertesa del sensor de radar és de 14 mm (dades mesurades espantades entre + 14 mm per a un objectiu fix). El disseny i la implementació real condueixen a aconseguir un excel·lent prototip de rendiment per a una aplicació no destructiva.[EN] Due to the relevance of application fields of ultra-wideband radar sensor, and also the requirement of each specific application, there is an increasing demand of compact, low cost and high accuracy design of ultra-wideband radar sensor. With a view to addressing these demands, this thesis aims to propose an advanced UWB radar sensor. This research work deals with the design of the ultra-wideband (UWB) radar sensor for non-destructive (NDT) application. The design details include the design of ultra-short, high power pulse generator monocycle pulse with a minimum of ringing. The developed radar was build in bi-static configuration. The goal of this work is to measure the distance range and electrical properties of a target e.g, metal and dielectric materials, such as Polyvinyl chloride (PV C). To achieve this goal, a novel ultrashort, high power pulse generator (radar pulser) has been developed. The new pulse generator consists of a transistor operating in avalanche mode and a pulse sharpening circuit using a new model of step recovery diode (SRD). In order to converts the Gaussian pulse to a monocycle, a monocycle forming network (MFN) has been added. The developed pulse generator produces an electrical pulse with an amplitude of 12 V, a rise-time of 112 ps and pulse width (FWHM) of 155 ps. For the purpose to increase the amplitude of the pulses, two useful techniques have been proposed in this work. The first one consist of adding two generators in parallel, in this proposed design some specification was be taking into account to making the workability of this circuit. However, the second technic adopted in this work consists of a two-stage of generators, both technics give rise to a good performance; instead of a single module of a pulse generator, the techniques proposed in this work increase the amplitude around the double. In order to transmit and receive the generated ultra-short pulses, two different types of UWB antennas have been used. First, a Vivaldi antenna with a bandwidth of about 5.5 GHz from 600 MHz to 6 GHz. While the second is a Vivaldi antenna with a bandwidth of 6 GHz from 400 Mhz to 6,2 GHz. Using the developed ultra-wideband radar sensor, test measurement was performed. These included electrical properties as well as distance measurement towards metal plates, wood, and PVC. The uncertainty of the radar sensor has been found to be 14 mm (measured data scared within + 14 mm for a fixed target). The design and real implementation leading to achieve excellent performance prototype for a non-destructive application.Ahajjam, Y. (2019). Design and Implementation of a UWB Radar Sensor for Non-Destructive Application [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/124057TESI