Dissertations / Theses on the topic 'Radio-tracking'

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 65-66).
This thesis presents WiTrack, a system that tracks the 3D motion of a user from the radio signals reflected off her body. It works even if the person is occluded from the WiTrack device or in a different room. WiTrack does not require the user to carry any wireless device, yet its accuracy exceeds current RF localization systems, which require the user to hold a transceiver. Empirical measurements with a WiTrack prototype show that, on average, it localizes the center of a human body to within a median of 10 to 13 cm in the x and y dimensions, and 21 cm in the z dimension. It also provides coarse tracking of body parts, identifying the direction of a pointing hand with a median of 11.2°. WiTrack bridges a gap between RF-based localization systems which locate a user through walls and occlusions, and human-computer interaction systems like Kinect, which can track a user without instrumenting her body, but require the user to stay within the direct line of sight of the device.
by Zachary Kabelac.
M. Eng.

Aircraft in the US are equipped with Emergency Locator Transmitters (ELTs). In emergency situations these beacons are activated, providing a radio signal that can be used to locate the aircraft. Recent developments in UAV technologies have enabled mini-UAVs (5-foot wingspan) to possess a high level of autonomy. Due to the small size of these aircraft they are human-packable and can be easily transported and deployed in the field. Using a custom-built Radio Direction Finder, we gathered readings from a known transmitter and used them to compare various Bayesian reasoning-based filtering algorithms. Using a custom-developed simulator, we were able to test and evaluate filtering and control methods. In most non-trivial conditions we found that the Sequential Importance Resampling (SIR) Particle Filter worked best. The filtering and control algorithms presented can be extended to other problems that involve UAV control and tracking with noisy non-linear sensor behavior.

Target tracking in over a small-scale area using wireless sensor networks (WSNs) is a technique that can be used in applications ranging from emergency rescue after an earthquake to security protection in a building. Many target tracking systems rely on the presence of an electric device which must be carried by the target in order to reports back its location and status. This makes these systems unsuitable for many emergency applications; in such applications device-free tracking systems that where no devices are attached to the targets are needed. Radio-Frequency (RF) tomographic tracking is one such device-free tracking technique. This system tracks moving targets by analyzing changes in attenuation in wireless transmissions. The target can be tracked within the sensor network area without being required to carry an electric device.Some previously-proposed device-free tracking approaches require a time-consuming training phase before tracking can be carried out, which is time-consuming. Others perform tracking by sacrificing part of the estimation accuracy. In this thesis, we propose a novel sequential Monte Carlo (SMC) algorithm for RF tomographic tracking. It can track a single target moving in a wireless sensor network without the system needing to be trained. The algorithm adopts a particle filtering method to estimate the target position and incorporates on-line Expectation Maximization (EM) to estimate model parameters. Based on experimental measurements, the work also introduces a novel measurement model for the attenuation caused by a target with the goal of improving estimation accuracy. The performance of the algorithm is assessed through numerical simulations and field experiments carried out with a wireless sensor network testbed. Both simulated and experimental results demonstrate that our work outperforms previous RF tomographic tracking approaches for single target tracking.
Suivi de cible dans la zone à petite échelle en utilisant les réseaux de capteurs sans fil est une technique qui peut être largement utilisé dans des applications telles que le sauvetage d'urgence après un tremblement de terre, ou la protection de la sécurité dans un bâtiment. Beaucoup de systèmes de poursuite de cibles nécessitent un dispositif électrique réalisée par l'objectif de faire rapport de ses localisation instantanée et le statut. L'inconvénient rend ces systèmes ne conviennent pas pour des applications nombreuses interventions d'urgence, dispositif sans systèmes de suivi qui ne les périphériques connectés sur les objectifs sont nécessaires. Radio-Fréquence (RF) suivi tomographique est l'une des techniques dispositif de suivi-libres. Il s'agit d'un processus de suivi des cibles mobiles en analysant l'évolution de l'atténuation dans les transmissions sans fil. La cible peut être suivi dans la zone de réseau de capteurs, tandis que les appareils électriques ne doivent être effectués. Cependant, certaines approches précédentes dispositif de suivi-libre nécessite une phase d'entraînement avant de suivi, ce qui prend beaucoup de temps. Autres effectuer un suivi par scarification partie de précision de l'estimation.Dans cette thèse, nous proposons une nouvelle Monte Carlo séquentielles (SMC) algorithme de suivi RF tomographique. Il peut suivre une cible unique sans formation du système dans un réseau de capteurs sans fil. L'algorithme de filtrage particulaire adopte la méthode pour estimer la position cible et intègre en ligne Expectation Maximization (EM) pour estimer les paramètres du modèle. Sur la base de mesures expérimentales, le travail introduit également un modèle de mesure de roman pour l'atténuation provoquée par une cible pour améliorer la précision d'estimation. La performance de l'algorithme est évaluée par des simulations numériques et expériences sur le terrain avec un réseau de capteurs sans fil banc d'essai. Les deux résultats simulés et expérimentaux démontrent que notre travail surpasse précédente approche RF suivi tomographique pour le suivi de cible unique.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2008.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references.
Since the first in situ observations of the Martian atmosphere were made by the twin Viking landers, we have learned considerably more about its composition, dynamics and variability. Not only did the new data on global atmospheric densities generate opportunities to understand the atmospheric composition of early Mars and supply constraints at the upper limit of General Circulation Models, it is critical for the design and planning of future exploration missions. We can complement the successes of remote sensing and accelerometer investigations by using radio tracking data that have not been studied from an atmospheric science perspective, or are available for the first time. Due to the very low density of the higher layers atmosphere, the estimation of the drag acceleration using Precision Orbit Determination is a challenge. We developed new numerical models of the non-conservative forces acting on the spacecraft. In particular, the spacecraft crosssectional area is calculated using improved spacecraft macro-models which include interplate shadowing. These improvements in the force modeling enable a more robust estimation of the atmospheric density. The density structure from the middle atmosphere up to the exosphere is studied using radio tracking data from the Mars Odyssey and the Mars Reconnaissance Orbiter spacecraft. Measurements in the Martian middle atmosphere, near 100 -- 110 km, are obtained from the aerobraking phase of the Mars Odyssey spacecraft; we obtain periapsis density estimates consistent with the Accelerometer Team, and estimate scale heights representative of the drag environment from an operational point of view. The orbit of Mars Odyssey during its mapping and extended phases allows us to probe very high in the exosphere, near 400 km altitude. In the retrieved density time series, we observe some of the features of solar forcing and seasonal cycle predicted by different atmospheric models.
(cont.) The most recent radio tracking data, from the Mars Reconnaissance Orbiter mapping mission, enables a monitoring of densities near 250 -- 300 km at higher temporal and spatial resolutions, allowing a more detailed study than previously possible.
by Erwan Mazarico.
Ph.D.

This thesis aims to compare methods of radio location for the purpose of tracking sheep by using sub-GHz radio transceivers arranged in a base station network. Nearly 10% of free-grazing sheep in Norway are lost every year, creating losses for both farmers and the government. Tracking technology may reduce these losses. Existing tracking solutions based on GPS and GSM are commercially available, but previous research shows that poor signal conditions in grazing areas limit their efficacy. An alternative tracking system using the low-power CC1120 transceiver from Texas Instruments is outlined and evaluated for the two following methods of radio location. Hyperbolic trilateration uses time difference of arrival (TDoA) estimates for receiver pairs and circular trilateration uses received signal strength (RSSI) to perform radio location. Initial measurements show that the transceiver alone should not be used for TDoA estimation because its trigger signals are only accurate to within 25% of the predetermined symbol interval. In future work, TDoA can be estimated by comparing the bit streams taken directly from the A/D-converter (ADC) of two base stations. This requires additional hardware but is expected to be accurate enough to locate sheep.A small-scale outdoors radio location experiment was carried out using RSSI measurements from the CC1120, and circular trilateration with three base stations approximately 200 m apart. A propagation model was fitted to calibration data using linear regression. Position estimates were calculated by both linear and non-linear least squares approximation using MATLAB. The average error of the position estimates was 55.8 m. The error in the full-scale system for this method is estimated to be several kilometres, too large for tracking sheep.In conclusion, the TDoA-based hyperbolic trilateration method is the only one showing promise. Challenges related to synchronicity between the base stations are expected to be met using GPS receivers. Additional work with extracting the bit streams is required before the TDoA can be estimated with sufficient accuracy.

Thesis (M.S. in Computer Science and M.S. in Applied Physics) Naval Postgraduate School, June 1999.
"June 1999". Thesis advisor(s): Rudy Darken, Xavier Maruyama. Includes bibliographical references (p.83-84). Also available online.

When a radio signal traverses the atmosphere it will be delayed by not only thedistance between transmitter and receiver, but also the atmosphere. Given knowl-edge of the characteristics of the sent signal the effect of the atmosphere can beobtained from the received signal. This concept is called radio occultation. Radiooccultation can provide high accuracy profiles of temperature, pressure and watervapour troughout the atmosphere.This report aims to present the work and results from a thesis performed atRUAG Space in Göteborg. The purpose of the thesis was to implement a simulatorwhich with high accuracy could generate a signal as it would have been receivedhad it propagated through the atmosphere.We will show that the generated signal passes the requirements that have beenset.
När en radiovåg passerar genom atmosfären kommer den att fördröjas, inte bara avavståndet mellan sändare och mottagare utan också av atmosfären. Givet kunskapom karaktäristiken hos den sända signalen kan atmosfärens effekt erhållas från denmottagna signalen. Detta koncept kallas för radio-ockultation. Radio-ockultationkan med hög noggrannhet ge profiler för temperatur, tryck och vattenånga genomatmosfären.Denna rapport ämnar presentera det jobb och de resultat som uppnåtts genomett examensarbete genomfört på RUAG Space i Göteborg. Examensarbetets syftevar att implementera en simulator som med hög noggrannhet kan generera ensignal så som den hade sett ut då den propagerat genom atmosfären.Vi kommer att visa att den genererade signalen uppnår de krav som ställts.

Satellites are often known for possessing invariable motion causing its apparent position to drift in the sky from the perspective of a ground station. If these irregular drifts are not compensated, the performance of the communication link would be greatly affected. Hence, the satellite motion has to be tracked by the ground station antenna. Arctic Space Technologies is a company based in northern Sweden that focuses on highly reliable and secure satellite data handling solutions; main with S-Band satellites in the Low Earth Orbit (LEO). This thesis consolidates a comprehensive research to implement a robust approach for ground stations to establish a secure connection for optimum satellite communication performance. The implementation will be conducted in the form of a software simulation using MATLAB and SIMULINK. The system proposed in this thesis relies on Two Line Elements (TLE) to obtain the parameters for the calculation of the orbital motion of the satellites and providing the azimuth and elevation angles for the antenna to point towards. However, although TLE data are fairly accurate; LEO satellites have a very small time period passing over a ground station for signals to be received and thus it is vital to ensure maximum signal strength is received for optimum performance in satellite communication. In order to do so, a Kalman filter is incorporated to reduce the antenna’s pointing error by adjusting the estimated trajectory in real time and manoeuvre the ground station accordingly.   This thesis uncovers through a theoretical review and simulation that accumulates and ensures the investigation of the primary data from the TLE; the main elements affecting the current situation and rectifying them to a certain extent using control systems. It furnishes with guidelines on how Radio Frequency (RF) signals from S-Band LEO satellites can be effectively communicated through a parabolic reflector as a ground station.

Doctor of Philosophy (PhD)
This thesis addresses the issues arising in range-only localisation and tracking using Radio Frequency Received Signal Strength Indicator measurements. One of the key issues in Radio Frequency (RF) based localisation and tracking applications is to obtain an accurate sensor representation. Such a sensor model is one of the prerequisites to achieve high accuracy and precision in the localisation and tracking task. The sensor models used at present for this task are very simplistic, and as a consequence are unable to achieve highly accurate and precise localisation. While such an accurate sensor description is desirable it has not been presented for RF sensors. This thesis addresses the task of obtaining an accurate sensor model for RF sensors. The major drawbacks of the most commonly used model, the nth power model, are demonstrated. A new model to satisfy the necessary requirements for high accuracy localisation is developed. This model is based on theoretical considerations and experimental data. It depicts the real occurring behaviour of RF sensors more closely than the models used so far for RF based range-only localisation. The use of this better sensor representation offers the possibility of achieving more accurate localisation. The expected performance of the alternative sensor model is compared to the commonly used nth power model. Furthermore, the inherent properties of the new sensor model are presented and their ramifications with regards to the goal of achieving highly accurate localisation are discussed. In addition to the sensor model development, the well-known probabilistic filtering techniques Kalman Filter, Particle Filter and Histogram Filter are compared and used to implement 1-dimensional and 2-dimensional range-only trackers. The filtering techniques are evaluated with respect to their suitability for appropriately handling the new multi-modal sensor model and the resulting multi-modal state distributions, and to provide correct and conclusive localisation and tracking results. Results from experiments using real data obtained in outdoor environments with a prototype RF localisation system as well as results obtained from simulations are presented in this thesis to validate the theoretical findings and the newly developed sensor model.

This thesis addresses the issues arising in range-only localisation and tracking using Radio Frequency Received Signal Strength Indicator measurements. One of the key issues in Radio Frequency (RF) based localisation and tracking applications is to obtain an accurate sensor representation. Such a sensor model is one of the prerequisites to achieve high accuracy and precision in the localisation and tracking task. The sensor models used at present for this task are very simplistic, and as a consequence are unable to achieve highly accurate and precise localisation. While such an accurate sensor description is desirable it has not been presented for RF sensors. This thesis addresses the task of obtaining an accurate sensor model for RF sensors. The major drawbacks of the most commonly used model, the nth power model, are demonstrated. A new model to satisfy the necessary requirements for high accuracy localisation is developed. This model is based on theoretical considerations and experimental data. It depicts the real occurring behaviour of RF sensors more closely than the models used so far for RF based range-only localisation. The use of this better sensor representation offers the possibility of achieving more accurate localisation. The expected performance of the alternative sensor model is compared to the commonly used nth power model. Furthermore, the inherent properties of the new sensor model are presented and their ramifications with regards to the goal of achieving highly accurate localisation are discussed. In addition to the sensor model development, the well-known probabilistic filtering techniques Kalman Filter, Particle Filter and Histogram Filter are compared and used to implement 1-dimensional and 2-dimensional range-only trackers. The filtering techniques are evaluated with respect to their suitability for appropriately handling the new multi-modal sensor model and the resulting multi-modal state distributions, and to provide correct and conclusive localisation and tracking results. Results from experiments using real data obtained in outdoor environments with a prototype RF localisation system as well as results obtained from simulations are presented in this thesis to validate the theoretical findings and the newly developed sensor model.

This thesis explores ways of modelling of animal movement that are applicable to empirical data, using the Eurasian sparrowhawk Accipiter nisus as the model species. Radio-tracking data on sparrowhawks were gathered during the breeding seasons of 2002 and 2003 in rural Aberdeenshire. In all, 15 sparrowhawks were tracked including provisioning males, females, non-breeding adults and dispersing juveniles. An analysis of quantified movements’ characteristics (move length, stopping times and distance from the nest site) in relation to behavioural, climatic and temporal variables, aggregated at various spatio-temporal scales, indicated that ambient temperature and wind speed affected sparrowhawk foraging range and the duration of foraging trips.  There was however, little temporal pattern in recorded movements. A method of quantifying home range movements is proposed whereby habitually used sites were identified using cluster analysis of radio-tracking locations.  The discrete movements around these sites by individual sparrowhawks can be considered as a Markov process and quantified in terms of a transition matrix.  The equilibrium properties of such a matrix are then used to quantify the expected long term distribution of the individual within the home range.  Modelling of transition probabilities suggests that much of the variation in observed movement patterns of three provisioning male sparrowhawks was explicable in terms of the spatial arrangement of the sites within the home range and that there was little variation between the behaviour of individual sparrowhawks. Finally, a mechanistic discrete space movement model was developed based on a few simple behavioural rules.

"Precise and accurate localization and motion classification is an emerging fundamental areas for scientific research and engineering developments. Such science and technology began from the broad out door area applications, and gradually grew into smaller and more complicated in-door area and more recently it is proceeding into in-body area networking for medical applications. Localization and motion classification technologies have their own specific challenges depending on the application and environment, which are left for scientists and engineers to overcome. One major challenge is that location estimation and motion classification often use hand-held devices or wearable sensors. Such devices and sensors usually work in indoor, near body environments and the human object has certain effects on the measurements. In that situation, existing mathematical models for general environments are no longer accurate and new models and analytical approaches are required to deal with the human body effects. This has opened opportunities for researchers to tackle a number of demanding problems. This dissertation focuses on three novel problems in localization and motion classification using radio propagation (RF) modeling, in and around the human body. (1) We develop an empirical Time-of-Arrival (TOA) ranging error model for radio propagation from body-mounted sensors to external access points, for human body tracking in indoor environment. This model reflects the effects of human angular motion on TOA ranging estimation, which enables accurate analysis for conventional TOA-based human tracking systems. (2) We use empirical data collected from a RF connection between a pair of body-mounted sensors to classify seven frequently appeared human body motions. This RF based classification approach has enabled health monitoring applications for first responders, hospital patient, and elderly care centers and in most of the situations it can replace the costly video base monitoring systems. (3) We use radio propagation models from body-mounted sensor to medical implants and the moving pattern of micro-robots inside the body to analyze the accuracy of hybrid localization inside the human body. This analysis demonstrates the feasibility of millimeter level of accurate localization inside the human body, which opens up possibilities for 3D reconstruction of the interior of human GI tract."

The wireless market of the future will demand inexpensive hardware, expandability, interoperability, and the implementation of advanced signal processing functions--i.e. a software radio. Configurable computing machines are often ideal software radio platforms. In particular, the Stallion reconfigurable processor's efficient hardware reuse and scalability fulfill these radios' demands. The advantages of Stallion-based design inspired an FPGA-based software radio - the proto-Stallion receiver. This thesis introduces the proto-Stallion architecture and details its implementation on the SLAAC-1V FPGA platform. Although this thesis presents a specific radio implementation, this architecture is flexible; it can support a variety of applications within its fixed framework. This implemented single-user DS-CDMA receiver utilizes an LMS adaptive filter that can combat MAI and constructively combine multipath; most notably, this receiver employs an adaptive tracking algorithm that harnesses the LMS algorithm to maintain symbol synchronization. The proto-Stallion receiver demonstrates the dependence of adaptive tracking on channel noise; the algorithm requires significant noise levels to maintain synchronization.
Master of Science

This thesis describes the developments of new models and toolkits for the orbit determination codes to support and improve the precise radio tracking experiments of the Cassini-Huygens mission, an interplanetary mission to study the Saturn system. The core of the orbit determination process is the comparison between observed observables and computed observables. Disturbances in either the observed or computed observables degrades the orbit determination process. Chapter 2 describes a detailed study of the numerical errors in the Doppler observables computed by NASA's ODP and MONTE, and ESA's AMFIN. A mathematical model of the numerical noise was developed and successfully validated analyzing against the Doppler observables computed by the ODP and MONTE, with typical relative errors smaller than 10%. The numerical noise proved to be, in general, an important source of noise in the orbit determination process and, in some conditions, it may becomes the dominant noise source. Three different approaches to reduce the numerical noise were proposed. Chapter 3 describes the development of the multiarc library, which allows to perform a multi-arc orbit determination with MONTE. The library was developed during the analysis of the Cassini radio science gravity experiments of the Saturn's satellite Rhea. Chapter 4 presents the estimation of the Rhea's gravity field obtained from a joint multi-arc analysis of Cassini R1 and R4 fly-bys, describing in details the spacecraft dynamical model used, the data selection and calibration procedure, and the analysis method followed. In particular, the approach of estimating the full unconstrained quadrupole gravity field was followed, obtaining a solution statistically not compatible with the condition of hydrostatic equilibrium. The solution proved to be stable and reliable. The normalized moment of inertia is in the range 0.37-0.4 indicating that Rhea's may be almost homogeneous, or at least characterized by a small degree of differentiation.

This thesis describes the developments of new models and toolkits for the orbit determination codes to support and improve the precise radio tracking experiments of the Cassini-Huygens mission, an interplanetary mission to study the Saturn system. The core of the orbit determination process is the comparison between observed observables and computed observables. Disturbances in either the observed or computed observables degrades the orbit determination process. Chapter 2 describes a detailed study of the numerical errors in the Doppler observables computed by NASA's ODP and MONTE, and ESA's AMFIN. A mathematical model of the numerical noise was developed and successfully validated analyzing against the Doppler observables computed by the ODP and MONTE, with typical relative errors smaller than 10%. The numerical noise proved to be, in general, an important source of noise in the orbit determination process and, in some conditions, it may becomes the dominant noise source. Three different approaches to reduce the numerical noise were proposed. Chapter 3 describes the development of the multiarc library, which allows to perform a multi-arc orbit determination with MONTE. The library was developed during the analysis of the Cassini radio science gravity experiments of the Saturn's satellite Rhea. Chapter 4 presents the estimation of the Rhea's gravity field obtained from a joint multi-arc analysis of Cassini R1 and R4 fly-bys, describing in details the spacecraft dynamical model used, the data selection and calibration procedure, and the analysis method followed. In particular, the approach of estimating the full unconstrained quadrupole gravity field was followed, obtaining a solution statistically not compatible with the condition of hydrostatic equilibrium. The solution proved to be stable and reliable. The normalized moment of inertia is in the range 0.37-0.4 indicating that Rhea's may be almost homogeneous, or at least characterized by a small degree of differentiation.

This thesis aims to address some of the deficiencies that exist in this discipline, in order to widen the applicability of biotelemetry methods and ultimately provide new data which will improve our understanding of animal movement strategies.

ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California
This document is focused on the examination of the tracking angular error due to the radio refraction for the target in low altitude of less than 5km and in low elevation angle. The real measured data using the GPS and the tracking systems of C- and S-band frequency in NARO Space centre, Korea are used for the analysis. The analysis shows couple of conclusions on the radio refraction effects; there are angular errors due to the radio refraction which is not to be neglected comparing the accuracy of the tracking system but to be considered for the precise measurement of the target position. Also, the refraction errors are dependent on the target altitude, but not on the frequency.

[ES] La llegada de la próxima generación del estándar de comunicaciones móviles, la llamada quinta generación (5G), es prácticamente una realidad. Las primeras redes comerciales han comenzado a ser desplegadas, centrándose en ofrecer altas velocidades de transferencia de datos. Sin embargo, el estándar 5G va mucho más allá y prevé dar soporte a nuevos servicios que pretenden revolucionar la sociedad. Estos nuevos servicios imponen un nivel alto de requisitos en no solo en cuanto a velocidad del tráfico de datos, sino en cuanto a latencia o número de dispositivos conectados simultáneamente. La amplia variedad de requisitos no puede ser soportada por las redes de cuarta generación (4G), por lo que se hizo necesario plantear un nuevo paradigma para las redes inalámbricas. Con la promesa de grandes cantidades de ancho de banda sin utilizar, el estándar 5G contempla utilizar frecuencias en la comúnmente conocida como banda de milimétricas (mmWave). Esta banda presenta grandes pérdidas de propagación, que se acentúan si existen bloqueos de señal. Actividades regulatorias del uso de las bandas de milimétricas atrajo el interés tanto de la industria como de la academia en plantear soluciones para dar servicio en estas bandas. En los últimos años se han presentado infinidad de trabajos basados en sistemas con múltiples antenas o MIMO, para conformar las señales transmitidas o recibidas en haces apuntando en determinadas direcciones. La ganancia que aportan los sistemas MIMO pueden compensar las altas pérdidas de propagación, asegurando la viabilidad de las comunicaciones mmWave. Se ha detectado una evidente falta de estudios sobre la viabilidad de sistemas MIMO en entornos móviles y dinámicos con bloqueos que hagan necesario que el sistema se reconfigure. Esta Tesis pretende cubrir este espacio desde un enfoque práctico y propone mecanismos de gestión de los haces para hacerles un seguimiento utilizando los recursos y mecanismos del nuevo estándar 5G. Las soluciones aportadas se basan en el uso eficiente de los reportes de medidas de las señales de referencia estandarizadas en enlace descendente. En primer lugar, esta Tesis recoge un análisis minucioso del estado del arte, donde se corrobora la necesidad de aportar soluciones de seguimiento de haces en sistemas de comunicaciones en la banda de milimétricas. Además, se estudian los diferentes mecanismos definidos en el estándar 5G y que posibilitan el seguimiento. Cabe destacar que el estándar no define un mecanismo único a seguir, permitiendo presentar propuestas. Una vez conocidas las tecnologías, se centra el estudio en el impacto del seguimiento sobre las prestaciones a nivel de red y de enlace. Dicho estudio se realiza sobre un sistema punto a punto, donde el terminal móvil se desplaza por un entorno urbano. En base a simulaciones de red, se cuantifica el índice de seguimiento de haz y de cómo dicho seguimiento afecta a la relación señal a ruido más interferencia (SINR) y la tasa de transmisión del usuario. Las soluciones de seguimiento propuestas en esta Tesis se pueden clasificar en dos categorías. En una primera categoría, se realiza el seguimiento en base a reportes de medidas de las señales de referencia. Independientemente de la velocidad, se alcanza un seguimiento del 91% con poca penalización en la tasa de transmisión si se monitorizan los haces de interés con una periodicidad menor de 20 ms. En la segunda categoría caben mecanismos de seguimiento que hacen uso de fuentes externas de información. Dentro de esta categoría, se propone un fingerprinting que relacione haces con la localización reportada y un modelo de machine learning (ML) que prediga los haces a utilizar. El fingerprinting proporciona los mismos niveles de rendimiento. Sin embargo, esta solución es muy sensible a errores y requiere considerar todos los casos posibles, lo que la hace tecnológicamente inviable. En cambio, el modelo de ML, que hace p
[CAT] L'arribada de la següent generació de l'estàndard de comunicacions mòbils, l'anomenada cinquena generació (5G), es pràcticament una realitat. Les primeres xarxes comercials han començat a desplegar-se i s'han centrat en oferir altes velocitats de transferència de dades. No obstant, l'estàndard 5G va molt mes allà y preveu donar suport a nous serveis que pretenen revolucionar la societat. Estos nous serveis imposen un alt nivell de requisits no sols en quant a velocitat de tràfic de dades, si no també en quant a latència o número de connexions simultànies. L'ampla varietat de requisits no es suportada per les xarxes de quarta generació (4G) actuals, per el qual es va fer necessari un nou paradigma de xarxes sense fil. Amb la promesa de amplies quantitats d'ample de banda, l'estàndard 5G contempla utilitzar freqüències a la banda de mil·limètriques. Esta banda presenta l'inconvenient d'experimentar grans pèrdues de propagació, que s'accentuen en cas de bloqueigs. L'apertura de les bandes de mil·limètriques va atraure l'interès tant de l'industria com de l'acadèmia en plantejar solucions per a donar servei en estes bandes. En els últims anys s'han presentat infinitat de treballs basats en sistemes amb múltiples antenes o MIMO, per a conformar els senyals transmesos o rebuts en feixos apuntant en determinades direccions d'interès. El guany de feix es pot utilitzar per a compensar les pèrdues de propagació, assegurant la viabilitat de les comunicacions en la banda de mil·limètriques. No obstant això, s'ha detectat una preocupant manca d'estudis sobre la viabilitat d'estos sistemes en entorns mòbils i dinàmics, amb obstacles que bloquejen els feixos i facen necessari que el sistema es reconfigure. El present treball de Tesi pretén cobrir este espai buit i des d'un punt de vista pràctic, es proposen mecanismes de gestió dels feixos per a ser el seguiment utilitzant els recursos i mecanismes dels que disposa l'estàndard 5G. D'esta manera, les solucions aportades es basen en la utilització eficient dels reports de mesures dels senyals de referència del enllaç descendent. En primer lloc, esta Tesi recull una anàlisi minuciosa de l'estat de l'art on es corrobora la necessitat de aportar solucions de seguiment de feixos per a comunicacions en la banda de freqüències mil·limètriques. A més a més, s'estudien els diferents mecanismes definits a l'estàndard 5G i que possibiliten el seguiment. Cap destacar que l'estàndard no defineix un mecanisme únic, si no que deixa la porta oberta a presentar propostes. Una vegada conegudes les tecnologies, l'estudi es centra en l'impacte del seguiment sobre les prestacions a nivell de xarxa i d'enllaç. Este estudi es realitza sobre un sistema MIMO punt a punt, en una única estació base i un terminal mòbil desplaçant-se en un entorn urbà. En base a simulacions d'extrem a extrem, es quantifica l'índex de seguiment de feix i com l'anomenat seguiment afecta a la relació senyal a soroll més interferència (SINR) i a la taxa instantània de transmissió de l'usuari. Les solucions de seguiment de feixos propostes a la Tesi es poden classificar en dos categories. A la primera categoria, el seguiment de feixos es realitza en base als reports de mesures dels senyals de referència. Independentment de la velocitat, s'arriba a una taxa de seguiment del 91% amb poca penalització de taxa de transmissió si els feixos d'interès es mesuren amb una periodicitat menor a 20 ms. A la segona categoria pertanyen els algoritmes que utilitzen fonts d'informació externes. Dins d'aquesta categoria es proposa un fingerprinting que relaciona un parell de feixos amb la ubicació de l'usuari, i a banda un model d'intel·ligència artificial (IA) que preveu el feix a utilitzar. El fingerprinting ofereix el mateix rendiment. Però, esta solució es molt sensible a errors i requereix considerar tots els casos possibles, fent-la tecnològicament inviable. En canvi, el
[EN] The arrival of the next generation of mobile communication standards, the so-called Fifth Generation (5G), is already a reality. The first commercial networks have begun to be deployed, and they focus on providing higher data rates. However, the 5G standard goes much further from that and aims at providing support to new services which will revolutionise the society. These new services impose a high level of requirements not only in terms of the data traffic speed, but also in terms of very low latency or incredibly large number of simultaneous connections. This wide variety of requirements cannot be technologically supported by the current Fourth Generation (4G) networks, so it became necessary to move forward with a new paradigm for wireless networks. With the promise of large amounts of bandwidth, in the order of GHz, the 5G standard contemplates the use of frequencies in the commonly known Millimetre Wave (mmWave) band. The mmWave band experiences large propagation losses, which are accentuated in blockage events. Regulatory activities worldwide in the mmWave bands attracted the interest of both the industry and the academia. In the last few years, a tremendous number of contributions on mmWave propagation studies and networks have appeared, most of them based on Multiple-Input Multiple-Output (MIMO) solutions. MIMO architectures allow to beamform, which focuses the radiated energy on certain directions of interest called beams. The additional beam gain compensates the high propagation losses, ensuring the viability of the communications in the mmWave band. There is an evident lack of viability studies of mmWave MIMO systems in mobile and highly-dynamic environments, where obstacles may block beams and forcing frequent re-configurations. This Thesis work aims to fill this gap from a practical approach. This Thesis proposes beam management mechanisms utilising the mechanisms and resources offered by the Third Generation Partnership Project (3GPP) 5G radio access standard: 5G New Radio (NR). The practical solutions are based on the efficient use of measurement reports of standardised downlink Reference Signals (RS). In first place, this Thesis provides a thorough state-of-the-art analysis and corroborates the need of adopting beam tracking solutions for mmWave networks. Then, a complete overview of the 5G standard mechanisms that enable beam tracking is given. The NR standard does not define a standardised mechanism for beam tracking, leaving the door open to proposals to carry out such monitoring. Once the technologies have been identified, the Thesis continues with assessing the impact of the beam tracking strategies on the network and link-level performance. The study is focused on individual point-to-point mmWave links in a realistic urban environment. Based on end-to-end network simulations, the Thesis is interested in assessing the beam tracking success ratio and how beam misalignment affects the perceived Signal to Noise plus Interference Ratio (SINR) and user throughput at pedestrian and vehicular speeds. The beam tracking solutions proposed in this Thesis fall into two categories. The first category monitors beams based on measuring and reporting beamformed RS. Regardless of the speed, this beam tracking category provides up to 91 % tracking performance, with little throughput reduction if the beams of interest are measured with a periodicity below 20 ms. Beam tracking in the second category relies on external information sources. Within this category, this Thesis proposes a fingerprinting database relating beams to the user position and a machine learning (ML) model. Fingerprinting beam tracking is technologically viable and provides similar performance levels. However, this solution is very sensitive to errors and requires considering all possible situations. The ML beam tracking, which makes predictions with a 16 % of estimation error for the reference data set.
I want to thank the Spanish Ministry of Education and Professional Formation for funding this Thesis work with an official pre-doctoral contract grant.
Herranz Claveras, C. (2019). Beam Tracking Strategies for 5G New Radio Networks Operating in the Millimetre Wave Bands [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/130845
TESIS

Thesis (Ph. D.) -- University of Maryland, College Park, 2007.
Thesis research directed by: Dept. of Civil and Environmental Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb. 19, 2008). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dr. Luis Occeña, Thesis Supervisor. Includes bibliographical references.

International Telemetering Conference Proceedings / October 28-31, 1985 / Riviera Hotel, Las Vegas, Nevada
Demonstration results are presented for a high dynamic GPS receiver. The receiver tested is a breadboard unit capable of tracking one simulated satellite signal in pseudorange and range rate. The receiver makes approximate maximum likelihood estimates of pseudorange and range rate each 20 ms, and tracks these observables using a third order filter with a time constant of 0.14 s. Carrier phase is not tracked, which eliminates the typical failure mode of loss of carrier lock associated with PLLs at high dynamics. The receiver tracks with pseudorange lag errors of under 0.06 m when subjected to simulated 50 g turns with 40 g/s peak jerk. Pseudorange errors due to receiver noise alone are approximately 0.6 m rms at a carrier power to noise spectral density ratio of 34 dB-Hz. The tracking threshold SNR is approximately 28 dB-Hz, which provides 12 dB margin relative to the 40 dB-Hz that occurs with minimum specified satellite signal strength, 3.5 dB system noise figure, and 0 dBi antenna gain.

Location systems for tracking people and objects have many potential applications, such as: safety, security, logistics, control, surveillance and automation. GPS is such a system, but does not work accurately indoors. This project was initiated to further investigate a location technique developed by Microsoft Research, using a wireless local area network with one mobile network point, and measuring the radio signal strength of the network communications between the mobile and fixed points. This project attempted to improve on this technique by investigating whether additional information and accuracy could be achieved by measuring signal strength over a range of frequencies.

Data association problem for multitarget tracking is determination of the relationship between targets and the incoming measurements from sensors of the target tracking system. Performance of a multitarget tracking system is strongly related to the chosen method for data association and target tracking algorithm. Incorrect data association effects state estimation of targets. In this thesis, we propose a new multi-scan data association algorithm for multitarget tracking systems. This algorithm was implemented by using MATLAB programming tool. Performances of the new algorithm and JPDA method for multiple targets tracking are compared. During simulations linear models are used and the uncertainties in the sensor and motion models are modeled by Gaussian density. Simulation results are presented. Results show that the new algorithm'
s performance is better than that of JPDA method. Moreover, a survey over target tracking literature is presented including basics of multitarget tracking systems and existing data association methods.

Within team sports, coaches aim to improve physical preparation by optimising the training process specific to competition. Unfortunately, at the elite level of wheelchair rugby (WCR) evidence-based information to guide this process is currently lacking. The present thesis investigates measures of external load during elite competition and explores whether this can be translated to inform current training practices. The first study established the suitability of a radio frequency-based, indoor tracking system (ITS) for the collection of movements specific to WCR. Minimal relative distance errors (< 0.2%) were seen across different sampling frequencies. Peak speed displayed the greatest relative error in 4 Hz tags (2%), with significantly lower errors observed in higher frequency tags (< 1%). The ITS was therefore deemed an acceptable tool for quantifying external load specific to WCR using a sampling frequency of 8 or 16 Hz. The external demands of elite competition were determined in Chapters 4 and 5. Notable differences in the volume of activity were displayed across the International Wheelchair Rugby Federation (IWRF) classification groups. However, the specific positional requirements of low-point (LP) and high-point players (HP) appeared to influence the intensity of external load (Chapter 4). Chapter 5 extended this work and established that peak speed and the ability to perform at high-intensities were best associated with successful mobility performance in WCR, as defined by team rank. This was further shown to be roledependent, whereby high-ranked HP players achieved greater peak speeds and performed more high-intensity activities (HIA) than respective lower-ranked players. Comparisons between the current external demands of training were then compared to that of competition (Chapter 6). Conditioning drills were shown to exceed the demands of competition, irrespective of classification. Notable differences in skill-based and game related drills were displayed across player classifications, whereby both were shown to be roledependent. Although game-simulation drills provided the best representation of competition, the duration appeared important since this factor influenced the results (Chapter 6). When the format of these drills were further modified (Chapter 7), drills containing fewer players increased the volume and intensity of training, specifically in HP. Whilst a 30-second shotclock elicited no changes in external load, differences were revealed when the shot-clock was further reduced to 15-s. Coaches can therefore modify the external training response by making subtle changes to the format of game-simulation drills. This thesis revealed that functional classification and positional-role are key factors during competition, and training should therefore be structured with this in mind. Conditioning drills can be used to elicit a progressive overload in the external responses, whilst game-simulation drills can provide the best representation of competition. Given the importance of gamesimulation drills, the combination of different formats throughout training sessions are critical in order to maximise the preparation of elite WCR players.

MBA Professional Report
The purpose of this MBA project is to assess industry business practices in implementing RFID technology in the tracking and tracing of pharmaceuticals. Our project will focus on what was found during our research (to include interviews and site visits) which was quite different from what was portrayed by the media. Our analysis of a few organizations will identify what market leaders do when considering the implementation of a new technology into its business practices. Based on our analysis, we determined what patterns were common throughout the industry and what DoD should be aware of as it implements RFID technology in the tracking and tracing of pharmaceuticals.

Positron emission particle tracking (PEPT) is a technique which non-invasively tracks tracer particles labelled with a positron emitting radionuclide in a system of flow. The tracers are tracked through the detection in a PET scanner, of the two nearly collinear 511 keV gamma rays resulting from the annihilations of the positrons. For this technique to be effective, the tracer must be representative of the media in the system under study, and labelled with a sufficient activity of radionuclides. Organic ion exchange resins are suitable tracer materials for PEPT experiments, and are usually labelled with ⁶⁸Ga at the laboratories of PEPT Cape Town. The labelling performance relies on the chemical and physical properties of organic strongly acidic cation exchange resins and the nuclear chemistry of ⁶⁸Ga. The objective of this study is to obtain consistent tracer labelling throughout, or even beyond, the lifespan of the SnO₂ ⁶⁸Ge/⁶⁸Ga generator which degrades over time. The objective 1s achieved by integrating a purification technique into a "standard" radiolabelling method used at iThemba LABS. A small 0.5 ml Amberchrom CG-71 column is loaded with the ⁶⁸Ga generator eluent in 7 M HCl, then rinsed of most the contaminants before eluting the product with distilled water and used in the radiolabelling method. Using a 1-year-old 30 mCi SnO₂ ⁶⁸Ge/⁶⁸Ga generator eluent that has been purified by this method improved the radiolabelling performance by an average of at least 10% when compared to the performance of the un-purified product. Purifying the generator eluent will enable PEPT experiments of longer duration, and in highly shielded systems where tracers with high activity are required, such as granular and fluid flow in engineering applications.

This thesis investigates a method of tracking remote transmitters using multipath localization fingerprints generated by a ray tracing simulation. Radio wave propagation phenomena in a dense urban environment can be simulated using publicly available mapping data and 2-D ray tracing techniques when the receivers and transmitters are found to be approximately co-planar. OpenStreetMap (OSM) building data is used to model the area of interest, and frequency of arrival (FOA) localization fingerprints are generated virtually along a grid. These fingerprints are then used to estimate the origin of incoming signals. Simulation of this method using three receivers and a 10 m square grid demonstrates a simulated localization accuracy within 15 m. Taking things a step closer to reality, an attempt to validate the ray tracing simulation is made. Validation is presented in the form of experimental results for a set of trials along with a statistical comparison to simulation results. A significant positive correlation between the experimental and simulation results is found and detailed. Finally, the tracking method described is applied to real collected signal data and the results discussed.

Voltaire wrote "With great power comes responsibility", a quote which can easily be applied to scientists nowadays whose work effectively shapes the life of billions of living beings, operating through various disciplines from medicine through to ecology. To help scientists working with wild creatures, animal-attached electronic devices, commonly referred to as 'tags', have become indispensable tools, pushing the boundaries into the unimaginable enabling, for instance, information to be sent from animals into space and back via satellites. This 'great power' does indeed come with 'responsibility' however, as evidence piles up of the deleterious effects of tags on their animal carriers. The aim of this doctoral project is to provide scientists with an analytical framework within which to examine the effects of external tags on wild animals with a view to providing guidelines informing best practise in animal tagging. For that purpose, an integrative, multidisciplinary approach was undertaken which, from a theoretical to an experimental level, assessed the impact of tags on birds. With a main focus on marine birds, the results show that tag effects ranged from behavioural aberrations to compromised energetics, ultimately reducing both flying and swimming performance. This impact varied as a function of tag size, mass, shape, position and attachment, as well as being dependent on bird morphology and lifestyle. The length of time to which a bird is exposed to deleterious tag effects appears critical since these effects can snowball over time. Fortunately, and as reported in this thesis, there are simple rules which can be implemented to help minimise tag impact even for long-term studies, mainly through an optimised tag design and innovative attachment system. So, happily, this thesis shows that by careful thinking, we can benefit maximally from our 'great power' and thus ensure that our 'responsibilities' to wild animals are best informed.

Current radio direction finding techniques are limited in flexibility and focus on specific applications. Commercial off the shelf systems exist for a wide range of applications from navigation to search and rescue and wildlife tracking. However these systems rely on commercially available VHF receivers and are limited in transmission modulation techniques and frequency ranges. The majority of these systems are expensive which places them outside the reach of most individuals while the current open source designs require specialized skills and knowledge to build. The goal of this work was to design a low cost system capable of determining the approximate location of a non-cooperative VHF transmitter that could easily be implemented on a variety of unmanned systems. One unmanned aerial system was designed, built, and evaluated. Existing open source hardware and software systems were utilized for the development of the pseudo Doppler direction finding system, and work was conducted utilizing recursive Bayesian techniques to estimate the VHF transmitter's location. Results and explanations of system behaviors are presented along with limitations and possible modifications to improve performance and reliability.
Master of Science
Radio direction finding uses specialized radio equipment to determine the direction that a radio signal is coming from. Commercial systems are often expense, and existing hobbyist designs require specialized skills, and both are not flexible in application or frequency. The same is true for commercially available drones, which tend to be expensive or face other limitations. In this work a low cost radio direction finding system that uses easily found open source hardware and software was built and evaluated, along with a low cost unmanned aerial system. Then using the data collected, a computer algorithm was tested that could estimate the transmitting radio’s location. After testing it was determined that all systems did work, but still had room for improvement. Future steps and system modifications are presented that could improve the system’s performance.

Navigation through large and unfamiliar facilities with labyrinths of corridors and rooms is difficult and often results in a person being lost. Additionally, locating a specific utility within a facility is often a tough task. The hypothesis tested in this research is that integrating real-time automated sensing technology and a Building Information Model will provide real time visualization that can assist in localization and navigation of a facility. The scope of this research is facility maintenance management during the Operation and Maintenance (O&M) phase of a facility. The thesis demonstrates how the integration of passive Radio Frequency Identification (RFID) tracking technology and Building Information Modeling (BIM) can assist in facilities maintenance management. The objectives of this research included 1) developing a framework that utilizes the integration of commercially-available RFID and a BIM model; 2) evaluating the framework for real-time resource location tracking within an indoor environment; and 3) developing an algorithm for real-time localization and visualization in a BIM model. A prototype application has been developed that simultaneously connects the RFID readers, a database, and a BIM model. The goal of this system is to have a real-time localization accuracy of 3 meters at 95% confidence. Testing was conducted in laboratory conditions, and the results show that the system error was within the 3 meters goal.

This research address the problem of inferring, through Radio-Frequency Identification (RFID) tracking data, the graph structures underlying social interactions in a group of rhesus macaques (a species of monkey). These social interactions are considered as independent affiliative and dominative components and are characterized by a variety of visual and auditory displays and gestures. Social structure in a group is an important indicator of its members’ relative level of access to resources and has interesting implications for an individual’s health. Automatic inference of the social structure in an animal group enables a number of important capabilities, including: 1. A verifiable measure of how the social structure is affected by an intervention such as a change in the environment, or the introduction of another animal, and 2. A potentially significant reduction in person hours normally used for assessing these changes. The behaviors of interest in the context of this research are those definable using the macaques’ spatial (x,y,z) position and motion inside an enclosure. Periods of time spent in close proximity with other group members are considered to be events of passive interaction and are used in the calculation of an Affiliation Matrix. This represents the strength of undirected interaction or tie-strength between individual animals. Dominance is a directed relation that is quantified using a heuristic for the detection of withdrawal and displacement behaviors. The results of an analysis based on these approaches for a group of 6 male monkeys that were tracked over a period of 60 days at the Yerkes Primate Research Center are presented in this Thesis.

A wide range of services and applications become possible when accurate position information for a radio terminal is available. These include: location-based services; navigation; safety and security applications. The commercial, industrial and military value of radio-location is such that considerable research effort has been directed towards developing related technologies, using satellite, cellular or local area network infrastructures or stand-alone equipment. This work studies and investigates two location techniques. The first one presents an implementation scheme for a wideband transmission and direction finding system using OFDM multi-carrier communications systems. This approach takes advantage of delay discrimination to improve angle-of-arrival estimation in a multipath channel with high levels of additive white Gaussian noise. A new methodology is interpreted over the multi carrier modulation scheme in which the simulation results of the estimated channel improves the performance of OFDM signal by mitigating the effect of frequency offset synchronization to give error-free data at the receiver, good angle of arrival accuracy and improved SNR performance. The full system simulation to explore optimum values such as channel estimation and AoA including the antenna array model and prove the operational performance of the OFDM system as implemented in MATLAB. The second technique proposes a low cost-effective method of tracking and monitoring objects (examples: patient, device, medicine, document) by employing passive radio frequency identification (RFID) systems. A multi-tag, (totalling fifty-six tags) with known ID values are attached to the whole patient’s body to achieve better tracking and monitoring precision and higher accuracy. Several tests with different positions and movements are implemented on six patients. The aim is to be able to track the patient if he/she is walking or sitting; therefore, the tests considered six possible movements for the patient including walking, standing, sitting, resting, laying on the floor and laying on the bed, these placements are important to monitor the status of the patient like if he collapsed and fall on the ground so that the help will be quick. The collected data from the RFID Reader in terms of Time Stamp, RSS, Tag ID, and a number of channels are processed using the MATLAB code.

MBA Professional Report
The purpose of this MBA project is to determine how effective the use of RFID and IUID can be in Marine Corps armories based on operating procedures, support of key organizations within the Departments of the Navy and the Marine Corps, and current research. This project's first objective is to examine the involvement, progress and procedures of organizations that are involved in supporting and improving the Marine Corps' armory processes. The second objective is to explore the feasibility of implementing RFID and/or UID technology into the current Marine Corps small arms tracking system based on current research. Feasibility and compatibility will be determined by examining the existing organizations, current business processes and information technology systems. The third objective is to examine the current research about the use of RFID and UID technology with small arms. The final objective is to provide recommendations for implementation of these technologies in the Marine Corps armory system.

"Submitted in partial fulfillment of the requirements for the degree of Master of Business Administration from the Naval Postgraduate School, December 2008."
Advisor(s): Ferrer, Geraldo ; Heath, Susan. "December 2008." "MBA professional report"--Cover. Description based on title screen as viewed on January 28, 2009. Includes bibliographical references (p. 89-93). Also available in print.

Migratory birds, some small and light weight as matchboxes, engage in seasonal inter-continental journeys in order to take advantage of the long summer days and abundance of food at northern latitudes to breed and raise their young, and then escape the harsh winters by migrating to lower latitudes. This thesis deals with two important aspects of migration, the routes taken during migration and the birds’ behaviour at stopovers. The migratory routes are for many species unknown, whole or in part, and this is especially true for species that migrate nocturnally. At stopovers birds replenish fuel reserves that powers migratory flight, and studying how birds utilise stopovers is important in order to understand how migration is organised. In this thesis I have used modern tracking technology to study both continental wide movements of thrush nightingales (Luscinia luscinia) and common rosefinches (Carpodacus erythrinus) using small light-level geolocators, and smaller scale movements at a single stopover site of garden warblers (Sylvia borin) using miniature radio-transmitters. I have also studied the fuelling behaviour of garden warblers during autumn migration in the field and in the lab, and great reed warblers (Acrocephalus arundinaceus) at a stopover site on Crete during spring migration after the Sahara crossing. The thesis discusses the significance of several aspects of migration shown by the birds that would have been very difficult to detect without the aid of modern tracking technology, such as loop migration, prolonged stops during migration, multiple wintering sites, and nocturnal relocations at stopover sites. Studies carried out at stopover sites also show that garden warblers and great reed warblers can attain large fuel loads even at sites where they have no barrier to cross and this might be a result of good foraging conditions. The thesis also highlights the importance of combining different techniques when studying stopover behaviour to get reliable estimates on stopover durations and fuel deposition rates as well as the importance of choosing sites preferred by birds when planning stopover studies.

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.