Development and evaluation of localization techniques for vehicular ad hoc networks and intelligent transportation systems

Orientadores: Leandro Aparecido Villas, Daniel Ludovico GuidoniDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: Devido aos diversos problemas nos sistemas de tráfego ocasionados pela evolução dos grandes centros urbanos, existe o campo de estudo dos Sistemas de Transportes Inteligentes (Intelligent Transportation Systems, ITS), que visa prover metodologias de comunicação, processamento e armazenamento de dados voltados para o segmento de transportes e comutação de pessoas nas cidades. Neste contexto, o advento das tecnologias de comunicação sem fio, sobretudo das tecnologias de comunicação sem fio dedicadas e de curto alcance, culminaram no surgimento do padrão de comunicação sem fio IEEE 802.11p para as redes veiculares (Vehicular Ad Hoc Netowrks, VANETs). Nos últimos anos, uma miríade de protocolos, aplicações e serviços vêm sendo desenvolvidos com os mais diversos objetivos, variando desde conforto a segurança. Muitos destes serviços confiam em algum sistema de localização, e necessitam de diferentes níveis de acurácia para seu pleno funcionamento. A solução imediata para localização em VANETS e ITS são os Sistemas de Navegação Global via Satélite (Global Navigation Satellite System, GNSS). No entanto, os sistemas GNSS sofrem problemas de inacurácia e indisponibilidade em zonas urbanas densas, rodovias multinível e túneis, o que representa um desafio para os protocolos, aplicações e serviços que confiam em localização. Com esta motivação, primeiramente foi realizada uma caracterização dos problemas de inacurácia e indisponibilidade dos sistemas GPS a partir de datasets reais. Foram selecionadas regiões no entorno de túneis. Uma vez que os nós da rede veicular são dotados de capacidade de comunicação sem-fio, processamento e armazenamento. Foram desenvolvidas e avaliadas as técnicas de localização Dead Reckoning e uma abordagem Cooperative Positioning onde os veículos compartilham suas estimativas de localização por meio da rede veicular com o objetivo de melhorar suas estimativas de localizações. As situações de indisponibilidade caracterizadas nos datasets foram reproduzidas em ambiente de simulação para validação das soluções de localização propostas. Resultados de simulação apresentam um ganho médio de 60% a 80% da solução Dead Reckoning em termos do Erro Médio Quadrático (Root Mean Square Erro, RMSE), se comparados com os resultados da solução stand alone GPS. Os resultados da solução Cooperative Positioning apresentam um ganho médio entre 80% e 92% no RMSE em relação a solução GPS stand alone, e entre 23% a 74% em relação a solução Dead Reckoning. Além disso, as soluções conseguem cobrir 100% das zonas de indisponibilidade do GPS nos cenários avaliadosAbstract: Due to the many problems in the traffic systems caused by the evolution of the large urban centers, there is the field of study of Intelligent Transportation Systems (ITS), which aims to provide communication, data processing and storage methodologies for the transport of people, assets and services in the cities. In this context, the advent of the wireless communications technologies especially the Dedicated Short Range Communications (DSRC), culminated in the development of the IEEE 802.11p standard for Vehicular Ad Hoc Networks (VANETs). In recent years, a myriad of protocols, applications, and services have been developed with a wide range of objectives, ranging from comfort to security. Many of these services rely on some location system, and require different levels of accuracy for their full operation. The Global Navigation Satellite Systems (GNSSs) are an off-the-shelf solution for localization in VANETS and ITS. However, GNSS systems suffer from problems of inaccuracy and unavailability in dense urban areas, multilevel roads and tunnels, posing a challenge for protocols, applications and services that rely on localization. With this motivation, we first carried out a characterization of the problems of inaccuracy and unavailability of GPS systems from real datasets. Regions were selected around tunnels. Since the nodes of the vehicular network are endowed with wireless communication, processing and storage capacbilities. A Dead Reckoning technique and a Cooperative Positioning approach were developed and evaluated. Vehicles share their location estimates using the vehicular network in order to improve their locations. The unavailability situations characterized in the data sets were reproduced in a simulation environment to validate the proposed localization solutions. Simulation results show an average gain of 60% to 80% of the Dead Reckoning solution in terms of RMSE, when compared to the results of the stand alone GPS solution. The results of the Cooperative Positioning solution show an average gain between 80% and 92% in the RMSE compared to the stand alone GPS solution, and between 23% and 74% in relation to the Dead Reckoning solution. In addition, the solutions can support 100% of the GPS unavailability zones on the evaluated cenariosMestradoCiência da ComputaçãoMestre em Ciência da Computação132244/2016-0CNP

Design and Implementation of System Components for Radio Frequency Based Asset Tracking Devices to Enhance Location Based Services. Study of angle of arrival techniques, effects of mutual coupling, design of an angle of arrival algorithm, design of a novel miniature reconfigurable antenna optimised for wireless communication systems

The angle of arrival estimation of multiple sources plays a vital role in the field of array signal processing as MIMO systems can be employed at both the transmitter and the receiver end and the system capacity, reliability and throughput can be significantly increased by using array signal processing. Almost all applications require accurate direction of arrival (DOA) estimation to localize the sources of the signals. Another important parameter of localization systems is the array geometry and sensor design which can be application specific and is used to estimate the DOA. In this work, various array geometries and arrival estimation algorithms are studied and then a new scheme for multiple source estimation is proposed and evaluated based on the performance of subspace and non-subspace decomposition methods. The proposed scheme has shown to outperform the conventional Multiple Signal Classification (MUSIC) estimation and Bartlett estimation techniques. The new scheme has a better performance advantage at low and high signal to noise ratio values (SNRs). The research work also studies different array geometries for both single and multiple incident sources and proposes a geometry which is cost effective and efficient for 3, 4, and 5 antenna array elements. This research also considers the shape of the ground plane and its effects on the angle of arrival estimation and in addition it shows how the mutual couplings between the elements effect the overall estimation and how this error can be minimised by using a decoupling matrix. At the end, a novel miniaturised multi element reconfigurable antenna to represent the receiver base station is designed and tested. The antenna radiation patterns in the azimuth angle are almost omni-directional with linear polarisation. The antenna geometry is uniplanar printed logspiral with striplines feeding network and biased components to improve the impedance bandwidth. The antenna provides the benefit of small size, and re-configurability and is very well suited for the asset tracking applications

Continuous Context Inference on Mobile Platforms

In this thesis we develop novel methods for continuous and sustained context inference on mobile platforms. We address challenges present in real-world deployment of two popular context recognition tasks within ubiquitous computing and mobile sensing, namely localization and activity recognition. In the first part of the thesis, we provide a new localization algorithm for mobile devices using the existing GSM communication infrastructures, and then propose a solution for energy-efficient and robust tracking on mobile devices that are equipped with sensors such as GPS, compass, and accelerometer. In the second part of the thesis we propose a novel sparse-coding-based activity recognition framework that mitigates the time-consuming and costly bootstrapping process of activity recognizers employing supervised learning. The framework uses a vast amount of unlabeled data to automatically learn a sensor data representation through a set of extracted characteristic patterns and generalizes well across activity domains and sensor modalities.Väitöskirjatyössä tarkastellaan kontekstien tunnistamista älypuhelimissa. Työssä esitellään uusia menetelmiä, jotka mahdollistavat tunnistamisalgoritmien käyttämisen pitkäkestoisesti osana joka päivän puhelinsovelluksia. Erityistarkastelussa ovat paikannus ja aktiviteettien tunnistus, kaksi keskeisintä kontekstintunnistuksen tutkimuksen osa-aluetta. Väitöskirjan ensimmäisessä osassa esitellään uusi GSM paikannusalgoritmi sekä kehitetään menetelmiä energiatehokkaaseen reitin ja paikan seurantaan älypuhelimissa. Väitöskirjan toisessa osassa kehitetään uusi lähestymistapa aktiviteettien tunnistamiseen käyttäen harvaa koodausta. Menetelmän periaatteena on etsiä yleisiä säännönmukaisuuksia havainnoista joiden luokkatietoa ei ole tiedossa. Löydettyjen säännönmukaisuuksien avulla voidaan johtaa uusi esitystapa havainnoille, joka mahdollistaa tunnistusalgoritmien kehittämisen merkittävästi vähäisemmän luokitellun datan avulla

Indoor positioning system for wireless sensor networks

Tese de Doutoramento - Programa Doutoral em Engenharia Electrónica e ComputadoresPositioning technologies are ubiquitous nowadays. From the implementation of the global positioning system (GPS) until now, its evolution, acceptance and spread has been unanimous, due to the underlying advantages the system brings. Currently, these systems are present in many different scenarios, from the home to the movie theatre, at work, during a walk in the park. Many applications provide useful information, based on the current position of the user, in order to provide results of interest. Positioning systems can be implemented in a wide range of contexts: in hospitals to locate equipment and guide patients to the necessary resources, or in public spaces like museums, to guide tourists during visits. They can also be used in a gymnasium to point the user to his next workout machine and, simultaneously, gather information regarding his fitness plan. In a congress or conference, the positioning system can be used to provide information to its participants about the on-going presentations. Devices can also be monitored to prevent thefts. Privacy and security issues are also important in positioning systems. A user might not want to be localized or its location to be known, permanently or during a time interval, in different locations. This information is therefore sensitive to the user and influences directly the acceptance of the system itself. Concerning outdoor systems, GPS is in fact the system of reference. However, this system cannot be used in indoor environment, due to the high attenuation of the satellite signals from non-line-of-sight conditions. Another issue related to GPS is the power consumption. The integration of these devices with wireless sensor networks becomes prohibitive, due to the low power consumption profile associated with devices in this type of networks. As such, this work proposes an indoor positioning system for wireless sensor networks, having in consideration the low energy consumption and low computational capacity profile. The proposed indoor positioning system is composed of two modules: the received signal strength positioning module and the stride and heading positioning module. For the first module, an experimental performance comparison between several received signal strength based algorithms was conducted in order to assess its performance in a predefined indoor environment. Modifications to the algorithm with higher performance were implemented and evaluated, by introducing a model of the effect of the human body in the received signal strength. In the case of the second module, a stride and heading system was proposed, which comprises two subsystems: the stride detection and stride length estimation system to detect strides and infer the travelled distance, and an attitude and heading reference system to provide the full three-dimensional orientation stride-by-stride. The stride detection enabled the identification of the gait cycle and detected strides with an error percentage between 0% and 0.9%. For the stride length estimation two methods were proposed, a simplified method, and an improved method with higher computational requirements than the former. The simplified method estimated the total distance with an error between 6.7% and 7.7% of total travelled distance. The improved method achieved an error between 1.2% and 3.7%. Both the stride detection and the improved stride length estimation methods were compared to other methods in the literature with favourable results. For the second subsystem, this work proposed a quaternion-based complementary filter. A generic formulation allows a simple parameterization of the filter, according to the amount of external influences (accelerations and magnetic interferences) that are expected, depending on the location that the device is to be attached on the human body. The generic formulation enables the inclusion/exclusion of components, thus allowing design choices according to the needs of applications in wireless sensor networks. The proposed method was compared to two other existing solutions in terms of robustness to interferences and execution time, also presenting a favourable outcome.Os sistemas de posicionamento fazem parte do quotidiano. Desde a implementação do sistema GPS (Global Positioning System) até aos dias que correm, a evolução, aceitação e disseminação destes sistemas foi unânime, derivada das vantagens subjacentes da sua utilização. Hoje em dia, eles estão presentes nos mais variados cenários, desde o lar até́ à sala de cinema, no trabalho, num passeio ao ar livre. São várias as aplicações que nos fornecem informação útil, usando como base a descrição da posição atual, de modo a produzir resultados de maior interesse para os utilizadores. Os sistemas de posicionamento podem ser implementados nos mais variados contextos, como por exemplo: nos hospitais, para localizar equipamento e guiar os pacientes aos recursos necessários, ou nas grandes superfícies públicas, como por exemplo museus, para guiar os turistas durante as visitas. Podem ser igualmente utilizados num ginásio para indicar ao utilizador qual a máquina para onde se deve dirigir durante o seu treino e, simultaneamente, obter informação acerca desta mesma máquina. Num congresso ou conferência, o sistema de localização pode ser utilizado para fornecer informação aos seus participantes sobre as apresentações que estão a decorrer no momento. Os dispositivos também podem ser monitorizados para prevenir roubos. Existem também questões de privacidade e segurança associados aos sistemas de posicionamento. Um utilizador poderá não desejar ser localizado ou que a sua localização seja conhecida, permanentemente ou num determinado intervalo de tempo, num ou em vários locais. Esta informação é por isso sensível ao utilizador e influencia diretamente a aceitação do próprio sistema. No que diz respeito aos sistemas utilizados no exterior, o GPS (ou posicionamento por satélite) é de facto o sistema mais utilizado. No entanto, em ambiente interior este sistema não pode ser usado, por causa da grande atenuação dos sinais provenientes dos satélites devido à falta de linha de vista. Um outro problema associado ao recetor GPS está relacionado com as suas características elétricas, nomeadamente os consumos energéticos. A integração destes dispositivos nas redes de sensores sem fios torna-se proibitiva, devido ao perfil de baixo consumo associado a estas redes. Este trabalho propõe um sistema de posicionamento para redes de sensores sem fio em ambiente interior, tendo em conta o perfil de baixo consumo de potência e baixa capacidade de processamento. O sistema proposto é constituído por dois módulos: o modulo de posicionamento por potência de sinal recebido e o módulo de navegação inercial pedestre. Para o primeiro módulo foi feita uma comparação experimental entre vários algoritmos que utilizam a potência do sinal recebido, de modo a avaliar a sua utilização num ambiente interior pré-definido. Ao algoritmo com melhor prestação foram implementadas e testadas modificações, utilizando um modelo do efeito do corpo na potência do sinal recebido. Para o segundo módulo foi proposto um sistema de navegação inercial pedestre. Este sistema é composto por dois subsistemas: o subsistema de deteção de passos e estimação de distância percorrida; e o subsistema de orientação que fornece a direção do movimento do utilizador, passo a passo. O sistema de deteção de passos proposto permite a identificação das fases da marcha, detetando passos com um erro entre 0% e 0.9%. Para o sistema de estimação da distância foram propostos dois métodos: um método simplificado de baixa complexidade e um método melhorado, mas com maiores requisitos computacionais quando comparado com o primeiro. O método simplificado estima a distância total com erros entre 6.7% e 7.7% da distância percorrida. O método melhorado por sua vez alcança erros entre 1.2% e 3.7%. Ambos os sistemas foram comparados com outros sistemas da literatura apresentando resultados favoráveis. Para o sistema de orientação, este trabalho propõe um filtro complementar baseado em quaterniões. É utilizada uma formulação genérica que permite uma parametrização simples do filtro, de acordo com as influências externas (acelerações e interferências magnéticas) que são expectáveis, dependendo da localização onde se pretende colocar o dispositivo no corpo humano. O algoritmo desenvolvido permite a inclusão/exclusão de componentes, permitindo por isso liberdade de escolha para melhor satisfazer as necessidades das aplicações em redes de sensores sem fios. O método proposto foi comparado com outras soluções em termos de robustez a interferências e tempo de execução, apresentando também resultados positivos

GPS precise positioning using multisensor data fusion for vehicular communication

Ph. D. Thesis.The Global Positioning System (GPS) is a widely used timing, navigation and positioning system. However, its performance can be signifi- cantly degraded by the effects of the various sources of noises due to a highly dynamic multipath environment, signal blockage or attenuation due to ionospheric perturbation. Therefore, the aim of this research is to enhance the GPS signal acquisition and tracking ability to mitigate these effects. Furthermore, it is desirable to provide continuous and consistent positioning information under GPS-denied environments with assistance from multi-sensor data fusion techniques. In this thesis, a novel GPS signal acquisition approach for very dense multipath environments, using a low cost innovative dual polarization patch antenna attached to GPS receiver, is implemented. This reduces the acquisition processing time significantly compared to the conventional serial searching approach. Furthermore, it successfully acquires extra satellites in a dense multipath environment. Furthermore, the GPS signal carrier tracking loop has been considered as one of the most important links in order to demodulate the navigation data frame. An innovative carrier tracking loop is also proposed that comprises two approaches, namely, the adaptive Kalman filter and the adaptive unscented Kalman filter, dynamically integrated with a third order phased locked loop respectively. The proposed two-carrier tracking loops are compared against the conventional carrier tracking loop and the results prove that the proposed approach is more robust and accurate. The carrier tracking performance employing this novel approach is improved, especially in highly dynamic and low CNR environments. Finally, in order to integrate GPS and the sensors, GPS, IMU (inertial measurement unit) and LiDAR are combined for data fusion. A novel line feature extraction and mapping algorithm was designed for LiDAR navigation with a low complexity that resulted in faster feature extraction. This was followed by an innovative integration scheme that combined GPS, IMU and LiDAR, which resulted in continuous, precise positioning data for vehicular communication, even when GPS signals are not available, in a harsh multipath environment

Pedestrian steering behaviour modelling within the built environment

Prediction of pedestrians’ steering behaviours within the built environments under normal and non-panic situations is useful for a wide range of applications, which include social science, psychology, architecture, and computer graphics. The main focus is on prediction of the pedestrian walking paths and the influences from the surrounding environment from the engineering point of view

A fuzzy logic approach to localisation in wireless local area networks

This thesis examines the use and value of fuzzy sets, fuzzy logic and fuzzy inference in wireless positioning systems and solutions. Various fuzzy-related techniques and methodologies are reviewed and investigated, including a comprehensive review of fuzzy-based positioning and localisation systems. The thesis is aimed at the development of a novel positioning technique which enhances well-known multi-nearest-neighbour (kNN) and fingerprinting algorithms with received signal strength (RSS) measurements. A fuzzy inference system is put forward for the generation of weightings for selected nearest-neighbours and the elimination of outliers. In this study, Monte Carlo simulations of a proposed multivariable fuzzy localisation (MVFL) system showed a significant improvement in the root mean square error (RMSE) in position estimation, compared with well-known localisation algorithms. The simulation outcomes were confirmed empirically in laboratory tests under various scenarios. The proposed technique uses available indoor wireless local area network (WLAN) infrastructure and requires no additional hardware or modification to the network, nor any active user participation. The thesis aims to benefit practitioners and academic researchers of system positioning