Modelos, Algoritmos y Protocolos para Redes de Comunicaciones Tolerantes a Interrupciones con Alto Grado de Predecibilidad

Tesis (DCI)--FCEFN-UNC, 2019La industria de las comunicaciones satelitales ha mostrado un avance limitado en las últimas décadas en comparación con la evolución de las redes terrestres tales como Internet. La razón principal consiste en que el entorno espacial es radicalmente diferente al terrestre, lo cual impacta considerablemente en la estabilidad de las conexiones y en el hecho de que los protocolos de comunicación utilizados en Tierra resulten inadecuados y/o ineficientes cuando se tratan de adaptar al espacio. Sin embargo, recientemente, y producto de un esfuerzo conjunto de diferentes agencias espaciales (NASA, ESA, CONAE, etc), se ha comenzado a estudiar y experimentar con estrategias de comunicaciones en red que son capaces de tolerar retardos e interrupciones mediante un cambio paradigmático en la forma de realizar dichas comunicaciones. En particular, se ha propuesto una arquitectura de protocolos llamada Delay/Disruption Tolerant Networking (DTN), y que dada la predecibilidad de las trayectorias satelitales, permite aprovechar un plande contactos compuesto por las oportunidades de comunicación en el futuro, lo que permite a los satélites tomar decisiones eficientes sobre cómo y cuándo transmitir el tráfico generado o recibido desde otros satélites. En los últimos años, se han llevado a cabo numerosos avances en la implementación de DTN y se han realizado experimentos en órbita que avalan el potencial beneficio de esta arquitectura. Además, se ha estudiado el problema del diseño del plan de contactos que constituye el proceso de configurar y elegir apropiadamente las oportunidades de comunicación con el objetivo de optimizar el rendimiento y realizar una adecuada gestión de los limitados recursos que se disponen en este tipo de redes. Sin embargo, esta arquitectura se encuentra aún en una etapa de maduración y son numerosos los desafíos que deben ser superados. En particular, en esta tesis se pone el foco en el problema de la congestión que ocurre cuando la planificación referida a la utilización de los recursos no resulta apropiada. Básicamente, se proponen mecanismos que actúan, por un lado, sobre el algoritmo de enrutamiento ejecutado de manera distribuida por los satélites de la red, y por otro, sobre el diseño automático del plan de contactos. Adicionalmente, se realizan aportes referidos a los problemas de incertidumbre y de escalabilidad e integración de la red. De esta manera, en esta investigación contribuimos con enfoques originales en los que se aprovecha la predictibilidad de las comunicaciones satelitales para proveer mecanismos de gestión y toma de decisiones de manera automatizada, solucionando de esta forma problemas cuya complejidad aumenta drásticamente con la cantidad de satélites y tiempos de evaluación. Cabe destacar además, que si bien los aportes realizados pueden ser utilizados de forma general en la arquitectura DTN, los mismos encuentran aplicación dentro del Plan Espacial Argentino, ya que esta arquitectura resulta particularmente adecuada para ser aplicada en las nuevas misiones satelitales distribuidas que propone CONAE para la observación terrestre. Por lo tanto, los aportes brindados en esta tesis tienen alcance hacia protocolos desarrollados mediante colaboraciones internacionales y podrían además ser utilizados en nuestro país para resolver desafíos de interés local

Visible light communication system based on software defined radio: Performance study of intelligent transportation and indoor applications

In this paper, our first attempt at visible light communication system, based on software defined radio (SDR) and implemented in LabVIEW is introduced. This paper mainly focuses on two most commonly used types of LED lights, ceiling lights and LED car lamps/tail-lights. The primary focus of this study is to determine the basic parameters of real implementation of visible light communication (VLC) system, such as transmit speed, communication errors (bit-error ratio, error vector magnitude, energy per bit to noise power spectral density ratio) and highest reachable distance. This work focuses on testing various multistate quadrature amplitude modulation (M-QAM). We have used Skoda Octavia III tail-light and Phillips indoor ceiling light as transmitters and SI PIN Thorlabs photodetector as receiver. Testing method for each light was different. When testing ceiling light, we have focused on reachable distance for each M-QAM variant. On the other side, Octavia tail-light was tested in variable nature conditions (such as thermal turbulence, rain, fog) simulated in special testing box. This work will present our solution, measured parameters and possible weak spots, which will be adjusted in the future.Web of Science84art. no. 43

Energy Harvesting Technologies for Achieving Self-Powered Wireless Sensor Networks in Machine Condition Monitoring:A Review

Condition monitoring can reduce machine breakdown losses, increase productivity and operation safety, and therefore deliver significant benefits to many industries. The emergence of wireless sensor networks (WSNs) with smart processing ability play an ever-growing role in online condition monitoring of machines. WSNs are cost-effective networking systems for machine condition monitoring. It avoids cable usage and eases system deployment in industry, which leads to significant savings. Powering the nodes is one of the major challenges for a true WSN system, especially when positioned at inaccessible or dangerous locations and in harsh environments. Promising energy harvesting technologies have attracted the attention of engineers because they convert microwatt or milliwatt level power from the environment to implement maintenance-free machine condition monitoring systems with WSNs. The motivation of this review is to investigate the energy sources, stimulate the application of energy harvesting based WSNs, and evaluate the improvement of energy harvesting systems for mechanical condition monitoring. This paper overviews the principles of a number of energy harvesting technologies applicable to industrial machines by investigating the power consumption of WSNs and the potential energy sources in mechanical systems. Many models or prototypes with different features are reviewed, especially in the mechanical field. Energy harvesting technologies are evaluated for further development according to the comparison of their advantages and disadvantages. Finally, a discussion of the challenges and potential future research of energy harvesting systems powering WSNs for machine condition monitoring is made

Unibo-BP: an innovative free software implementation of Bundle Protocol Version 7 (RFC 9171)

The BP (Bundle Protocol) version 7 has been recently standardized by IETF in RFC 9171, but it is the whole DTN (Delay-/Disruption-Tolerant Networking) architecture, of which BP is the core, that is gaining a renewed interest, thanks to its planned adoption in future space missions. This is obviously positive, but at the same time it seems to make space agencies more interested in deployment than in research, with new BP implementations that may challenge the central role played until now by the historical BP reference implementations, such as ION and DTNME. To make Unibo research on DTN independent of space agency decisions, the development of an internal BP implementation was in order. This is the goal of this thesis, which deals with the design and implementation of Unibo-BP: a novel, research-driven BP implementation, to be released as Free Software. Unibo-BP is fully compliant with RFC 9171, as demonstrated by a series of interoperability tests with ION and DTNME, and presents a few innovations, such as the ability to manage remote DTN nodes by means of the BP itself. Unibo-BP is compatible with pre-existing Unibo implementations of CGR (Contact Graph Routing) and LTP (Licklider Transmission Protocol) thanks to interfaces designed during the thesis. The thesis project also includes an implementation of TCPCLv3 (TCP Convergence Layer version 3, RFC 7242), which can be used as an alternative to LTPCL to connect with proximate nodes, especially in terrestrial networks. Summarizing, Unibo-BP is at the heart of a larger project, Unibo-DTN, which aims to implement the main components of a complete DTN stack (BP, TCPCL, LTP, CGR). Moreover, Unibo-BP is compatible with all DTNsuite applications, thanks to an extension of the Unified API library on which DTNsuite applications are based. The hope is that Unibo-BP and all the ancillary programs developed during this thesis will contribute to the growth of DTN popularity in academia and among space agencies

Design and Analysis of Free-space Optical Communications Systems for Next Generation Short-range Wireless Networks

This dissertation focuses on indoor free-space optical communications systems for use in short range wireless networks. We propose that current radio frequency wireless links be augmented or replaced with optical frequency links due to overcrowding in the radio frequency spectrum. Optical frequencies contain hundreds of terahertz of unregulated bandwidth and offer a physical layer of protection due to the inherently line-of-sight nature of near infrared light. We first present a hybrid optical and radio frequency link based on inexpensive LEDs in which a downlink is established optically, while the uplink is routed through preexisting radio frequency channels. Second, an all optical dual channel laser-based communication system is implemented consisting of a medium bandwidth wide-angle optical femtocell and a high-speed line-of-sight optical attocell. This approach balances the diverse needs of end users by providing links optimized for both mobility and bandwidth. Lastly, we demonstrate a high-power vertical cavity surface emitting laser (VCSEL) array transmitter for use in optical femtocells. A complimentary design for a distributed current laser driver is also presented

Array processing techniques for direction of arrival estimation, communications, and localization in vehicular and wireless sensor networks

Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2018.Técnicas de processamentos de sinais para comunicações sem fio tem sido um tópico de interesse para pesquisas há mais de três décadas. De acordo com o padrão Release 9 desenvolvido pelo consorcio 3rd Generation Partnership Project (3GPP) sistemas utilizando múltiplas antenas foram adotados na quarta geração (4G) dos sistemas de comunicação sem fio, também conhecida em inglês como Long Term Evolution (LTE). Para a quinta geração (5G) dos sistemas de comunicação sem fio centenas de antenas devem ser incorporadas aos equipamentos, na arquitetura conhecida em inglês como massive multi-user Multiple Input Multiple Output (MIMO). A presença de múltiplas antenas provê benefícios como o ganho do arranjo, ganho de diversidade, ganho espacial e redução de interferência. Além disso, arranjos de antenas possibilitam a filtragem espacial e a estimação de parâmetros, ambos podem ser usados para se resolver problemas que antes não eram vistos pelo prisma de processamento de sinais. O objetivo dessa tese é superar a lacuna entre a teoria de processamento de sinais e as aplicações da mesma em problemas reais. Tradicionalmente, técnicas de processamento de sinais assumem a existência de um arranjo de antenas ideal. Portanto, para que tais técnicas sejam exploradas em aplicações reais, um conjunto robusto de métodos para interpolação do arranjo é fundamental. Estes métodos são desenvolvidos nesta tese. Além disso problemas no campo de redes de sensores e redes veiculares são tratados nesta tese utilizando-se uma perspectiva de processamento de sinais. Nessa tesa métodos inovadores de interpolação de arranjos são apresentados e sua performance é testada utilizando-se cenários reais. Conceitos de processamento de sinais são implementados no contexto de redes de sensores. Esses conceitos possibilitam um nível de sincronização suficiente para a aplicação de sistemas de múltiplas antenas distribuídos, o que resulta em uma rede com maior vida útil e melhor performance. Métodos de processamento de sinais em arranjos são propostos para resolver o problema de localização baseada em sinais de rádio em redes veiculares, com aplicações em segurança de estradas e proteção de pedestres. Esta tese foi escrita em língua inglesa, um sumário em língua portuguesa é apresentado ao final da mesma.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).Array signal processing in wireless communication has been a topic of interest in research for over three decades. In the fourth generation (4G) of the wireless communication systems, also known as Long Term Evolution (LTE), multi antenna systems have been adopted according to the Release 9 of the 3rd Generation Partnership Project (3GPP). For the fifth generation (5G) of the wireless communication systems, hundreds of antennas should be incorporated to the devices in a massive multi-user Multiple Input Multiple Output (MIMO) architecture. The presence of multiple antennas provides array gain, diversity gain, spatial gain, and interference reduction. Furthermore, arrays enable spatial filtering and parameter estimation, which can be used to help solve problems that could not previously be addressed from a signal processing perspective. The aim of this thesis is to bridge some gaps between signal processing theory and real world applications. Array processing techniques traditionally assume an ideal array. Therefore, in order to exploit such techniques, a robust set of methods for array interpolation are fundamental and are developed in this work. Problems in the field of wireless sensor networks and vehicular networks are also addressed from an array signal processing perspective. In this dissertation, novel methods for array interpolation are presented and their performance in real world scenarios is evaluated. Signal processing concepts are implemented in the context of a wireless sensor network. These concepts provide a level of synchronization sufficient for distributed multi antenna communication to be applied, resulting in improved lifetime and improved overall network behaviour. Array signal processing methods are proposed to solve the problem of radio based localization in vehicular network scenarios with applications in road safety and pedestrian protection