EVEREST IST - 2002 - 00185 : D23 : final report

Deliverable públic del projecte europeu EVERESTThis deliverable constitutes the final report of the project IST-2002-001858 EVEREST. After its successful completion, the project presents this document that firstly summarizes the context, goal and the approach objective of the project. Then it presents a concise summary of the major goals and results, as well as highlights the most valuable lessons derived form the project work. A list of deliverables and publications is included in the annex.Postprint (published version

Methodologies for Future Vehicular Digital Twins

The role of wireless communications in various domains of intelligent transportation systems is significant; it is evident that dependable message exchange between nodes (cars, bikes, pedestrians, infrastructure, etc.) has to be guaranteed to fulfill the stringent requirements for future transportation systems. A precise site-specific digital twin is seen as a key enabler for the cost-effective development and validation of future vehicular communication systems. Furthermore, achieving a realistic digital twin for dependable wireless communications requires accurate measurement, modeling, and emulation of wireless communication channels. However, contemporary approaches in these domains are not efficient enough to satisfy the foreseen needs. In this position paper, we overview the current solutions, indicate their limitations, and discuss the most prospective paths for future investigation.Comment: Submitted to IEEE Intelligent Transportation Systems Magazin

Algorithms for propagation-aware underwater ranging and localization

Mención Internacional en el título de doctorWhile oceans occupy most of our planet, their exploration and conservation are one of the crucial research problems of modern time. Underwater localization stands among the key issues on the way to the proper inspection and monitoring of this significant part of our world. In this thesis, we investigate and tackle different challenges related to underwater ranging and localization. In particular, we focus on algorithms that consider underwater acoustic channel properties. This group of algorithms utilizes additional information about the environment and its impact on acoustic signal propagation, in order to improve the accuracy of location estimates, or to achieve a reduced complexity, or a reduced amount of resources (e.g., anchor nodes) compared to traditional algorithms. First, we tackle the problem of passive range estimation using the differences in the times of arrival of multipath replicas of a transmitted acoustic signal. This is a costand energy- effective algorithm that can be used for the localization of autonomous underwater vehicles (AUVs), and utilizes information about signal propagation. We study the accuracy of this method in the simplified case of constant sound speed profile (SSP) and compare it to a more realistic case with various non-constant SSP. We also propose an auxiliary quantity called effective sound speed. This quantity, when modeling acoustic propagation via ray models, takes into account the difference between rectilinear and non-rectilinear sound ray paths. According to our evaluation, this offers improved range estimation results with respect to standard algorithms that consider the actual value of the speed of sound. We then propose an algorithm suitable for the non-invasive tracking of AUVs or vocalizing marine animals, using only a single receiver. This algorithm evaluates the underwater acoustic channel impulse response differences induced by a diverse sea bottom profile, and proposes a computationally- and energy-efficient solution for passive localization. Finally, we propose another algorithm to solve the issue of 3D acoustic localization and tracking of marine fauna. To reach the expected degree of accuracy, more sensors are often required than are available in typical commercial off-the-shelf (COTS) phased arrays found, e.g., in ultra short baseline (USBL) systems. Direct combination of multiple COTS arrays may be constrained by array body elements, and lead to breaking the optimal array element spacing, or the desired array layout. Thus, the application of state-of-the-art direction of arrival (DoA) estimation algorithms may not be possible. We propose a solution for passive 3D localization and tracking using a wideband acoustic array of arbitrary shape, and validate the algorithm in multiple experiments, involving both active and passive targets.Part of the research in this thesis has been supported by the EU H2020 program under project SYMBIOSIS (G.A. no. 773753).This work has been supported by IMDEA Networks InstitutePrograma de Doctorado en Ingeniería Telemática por la Universidad Carlos III de MadridPresidente: Paul Daniel Mitchell.- Secretario: Antonio Fernández Anta.- Vocal: Santiago Zazo Bell

Wireless Channel Models for Indoor Environments

Wireless networks have made significant advancement in recent times by adding a new dimension to theway people communicate. Development of wireless standards have constantly aimed at providing higher datarates even under complex environments using smart antennas, multiple-input, and multiple-output systems.This has necessitated an understanding of the indoor propagation channel. Channel models describe acommunication channel and are essential in developing efficient wireless communication networks. This papersurveys different channel models used to characterise wireless indoor environment. This survey may be usefulfor the army, where the communication over wide areas during wargames that they hold periodically, isnecessary. Moreover, it may also be useful for communication near the border areas for surveillance operations.Defence Science Journal, 2008, 58(6), pp.771-777, DOI:http://dx.doi.org/10.14429/dsj.58.170

Vehicular Communication in Obstructed and Non Line-of-Sight Scenarios

Since the invention of the first car available to masses, the 1908 Ford Model T, technology has advanced towards making car travel safer for occupants and bystanders. In recent years, wireless communication has been introduced in the vehicular industry as a means to avoid accidents and save lives.Wireless communication may sometimes be challenging due to obstacles in the physical world that interact with wireless signals. Such obstacles may be dynamic, e.g. other vehicles in the traffic flow, or static, e.g. nearby buildings. Two scenarios are defined to describe those cases. The obstructed line-of-sight (OLOS) scenario is described as the case where a smaller obstacle, usually a vehicle, is placed in-between a transmitter and a receiver. This obstacle usually partially blocks communication and the receiver often moves in an out of the line-of-sight. The non line-of-sight (NLOS) scenario is described as the case where a larger obstacle completely blocks communication between a transmitter and a receiver. An example would be a building at an intersection which shadows the communication between two vehicles. In this thesis the OLOS and NLOS scenarios are investigated from different points of view.In chapter 2, a road side unit (RSU) that has been constructed and evaluated for integrating older vehicles without wireless communication with newer vehicles using wireless communication is described. Older vehicles are being detected using a universal medium-range radar and their position and speed vectors are broadcasted wirelessly to newer vehicles. Tests have been performed by using the system in parallel with wireless enabled vehicles; by comparing the content in the messages obtained from both systems, the RSU has been found to perform adequately. Accuracy tests have been performed on the system and Kalman filtering has been applied to improve the accuracy even further.Chapter 3 focuses on the OLOS scenario. A truck as an obstacle for wireless vehicular communication is being investigated. Real life measurements have been performed to characterize and model the wireless channel around the truck. The distance dependent path loss and additional shadowing loss due to the truck is analyzed through dynamic measurements. The large scale fading, delay and Doppler spreads are characterized as a measure of the channel dispersion in the time and frequency domains. It has been found that a truck as an obstacle reduces the received power by 12 and 13 dB on average in rural and highway scenarios, respectively. Also, the dispersion in time and frequency domains is highly increased when the line-of-sight is obstructed by the truck. A model for power contributions due to diffraction around the truck has also been proposed and evaluated using the previously mentioned real life measurements. It has been found that communication may actually be possible using solely diffraction around a truck as a propagation mechanism.Finally, in chapter 4 a wireless channel emulator that has been constructed and evaluated is described. Modem manufacturers face a challenge when designing and implementing equipment for highly dynamic environments found in vehicular communication. For testing and evaluation real-life measurements with vehicles are required, which is often an expensive and slow process. The channel emulator proposed is designed and implemented using a software defined radio (SDR). The emulator together with the proposed test methodology enables quick on-bench evaluation of wireless modems. It may also be used to evaluate modem performance in different NLOS and OLOS scenarios

Measurement techniques enhancements for MIMO 4G mobile communication systems. extension of mode stirred reverberation chambers (MSRCs) emulation capabilities

[ENG] Mobile communications have experienced a brutal raise over the past 15 years. What started as a voice communication system (GSM or 2G) has finished yet as a data communication system of any kind, which in some cases has come to replace the conventional cabled data access infrastructure. This change in the use given to mobile devices necessarily entails a change in the underlying technology, which should be capable to provide the transmission speeds that these new applications require. This has emerged in recent years an increasing interest in multiple antenna techniques, usually referred as multiple-input multiple-output (MIMO) techniques, as they increase the spectral efficiency (and thus the transmission rate for a given bandwidth) of wireless systems. In this thesis, some of the factors limiting the ideal advantages of these multiantenna techniques are studied, in order to quantify the differences between the ideal behavior of 4G devices and behavior that users will experience in actual use conditions. The effect that the user has on the final performance of the devices is one of the main limitations that these devices are in daily use. Mobile phones are used almost all the time in the vicinity of the user, causing a decrease in the richness of the multipath electromagnetic environment (and thus a reduction of the MIMO benefits). As a result of this reduction, the number of signal paths that reach the user is also reduced. In this thesis both factors (user influence and influence of the number of signal paths) will be studied both for passive devices (antenna prototypes) and active devices (commercial phones). The second part of this thesis consist on the study of how to transfer some of these factors reducing the isotropicity of the environment, to one of the most promising measurement techniques, as it is the mode-stirred reverberation chamber (MSRC). This technique emulates naturally an isotropic rich multipath environment with the signal strength following a Rayleigh distribution. However, in this thesis two new techniques are proposed that allow the emulation of less isotropic environments without altering the basic operating principle of the MSRC. [SPA] Las comunicaciones móviles han experimentado un aumento brutal en los últimos 15 años. Lo que comenzó como un sistema de comunicación de voz (GSM o 2G) ha terminado todavía como un sistema de comunicación de datos de cualquier tipo, que en algunos casos ha llegado a sustituir la infraestructura de cableado convencional de acceso a datos. Este cambio en el uso que se da a los dispositivos móviles implica necesariamente un cambio en la tecnología subyacente, que debe ser capaz de proporcionar las velocidades de transmisión que estas nuevas aplicaciones requieren. Esto se ha convertido en los últimos años un creciente interés en las técnicas de múltiples antenas, normalmente se conoce como técnicas de múltiple entrada y múltiple salida (MIMO), ya que aumentan la eficiencia espectral (y por lo tanto la velocidad de transmisión para un ancho de banda dado) de los sistemas inalámbricos. En esta tesis, algunos de los factores que limitan las ventajas ideales de estas técnicas de múltiples antenas son estudiados, con el fin de cuantificar las diferencias entre el comportamiento ideal de dispositivos 4G y comportamiento que los usuarios experimentarán en condiciones reales de uso. El efecto que el usuario tiene sobre el rendimiento final de los dispositivos es una de las principales limitaciones que estos dispositivos son de uso diario. Los teléfonos móviles se utilizan en casi todo el tiempo en la proximidad del usuario, causando una disminución en la riqueza del entorno electromagnético trayectos múltiples (y por tanto una reducción de los beneficios MIMO). Como resultado de esta reducción, el número de trayectorias de señal que llegan al usuario también se reduce. En esta tesis ambos factores (la influencia del usuario y la influencia del número de caminos de señal) se estudió tanto para dispositivos pasivos (prototipos de antenas) y los dispositivos activos (los teléfonos comerciales). La segunda parte de esta tesis consisten en el estudio de cómo transferir algunos de estos factores que reducen la isotropicity del medio ambiente, a una de las técnicas de medición más prometedores, como es la cámara de agitación de modos (MSRC). Esta técnica emula naturalmente un entorno isotrópico multipath rico con la intensidad de la señal después de una distribución de Rayleigh. Sin embargo, en esta tesis, dos nuevas técnicas que se proponen permitir la emulación de entornos isotrópicos menos sin alterar el principio de funcionamiento básico del MSRC.Universidad Politécnica de Cartagen