Spectrum Engineering Towards 5G: Helping to Ensure Efficient and Interference-free Wireless Communications

With the current use of mobile devices across the world, with increasing demands on bandwidth resources, solving the congestion in the radio spectrum is becoming a challenging task to spectrum regulators. Radiocommunication systems must share the resources efficiently using different multiplexing techniques using space, frequency or time dimension. Sharing and compatibility studies are required to assess the possibilities for radio systems to coexist in the same or in adjacent frequency bands. SEAMCAT  (www.seamcat.org) is a software tool based on the Monte-Carlo simulation method, which is developed within the frame of European Conference of Postal and Telecommunication administrations (CEPT). This tool permits statistical modelling of different radio interference scenarios for performing sharing and compatibility studies between radio-communications systems in the same or adjacent frequency. SEAMCAT is used by many regulatory agencies across the world for various spectrum sharing and compatibility studies such as between mobile systems and terrestrial broadcasting networks.IEEE Latvia sectioninfo:eu-repo/semantics/publishedVersio

Bragg grating tuning techniques for interferometry applications

Fiber bragg grating is widely used in optical fiber applications as a filter or a sensor due to its compact size and high sensitivity to physical conditions, such as temperature and strain. The purpose of this chapter is to describe the implementation and characterization of two tuning methods for optical fiber Bragg gratings, varying the temperature or the length of the fiber. Among the methods using mechanical deformation, compression of the fiber by bending a flexible sheet aggregated with the Bragg grating has shown very interesting tuning results, reaching 19.0 nm with minimum reflection bandwidth variation over the entire tuning range. Stretching the fiber has presented several drawbacks, including breaking of the fiber and a lower tuning range of 4.9 nm. Temperature tuning technique presents good linearity between tuning range and temperature variation but at the cost of a low tuning range (0.4 nm) and a permanent high current electrical source.info:eu-repo/semantics/publishedVersio

Design-With-IoT and Design-For-Automation: A Proposal for Product Development Oriented for Excellence

This paper presents two methodologies for the design and development of new products called Design-with- IoT (DwIoT) that aims to integrate IoT technology into products, focusing on a set of guidelines for its implementation, and the concept of Design-for-Automation (DFA), important in the development of new automation oriented products in an industry 4.0 context.info:eu-repo/semantics/publishedVersio

Distributed sensing network using ultra low-power lora nodes: a case study in intensive almond groves

The digitization of various agricultural processes is a growing reality in Portugal and in the world. Some of the application areas use sensor networks to monitor several parameters, including monitoring plant growth, atmospheric conditions or optimizing the irrigation process. However, in the agricultural environment where energy sources may be scarce, the implementation of an autonomous sensor network must consider the limitations imposed by the energy consumption of sensor nodes, powered by batteries. Moreover, spatial distribution models must be tested to optimize the number of sensors and their placement in the field. This paper presents an ongoing work, being developed in partnership with a company, owner of an extensive almond grove in the region of Idanha-a-Nova and Fundão, Portugal. The objective is to implement a sensor network, making use of a LoRa technology and battery-powered nodes, and collect information on various parameters associated with intensive almond trees groves. The proposed sensor network is part of an IoT middleware framework that captures multiple data from different sources. Through smart farming, precision agriculture, real time monitoring and business intelligence solutions, the expected results are productivity increase and optimization of the use of resources in the almond cultivation process and a significative reduction of the environmental impact.N/

Modulação e conversão de formatos óticos avançados

Doutoramento em Engenharia ElectrotécnicaOver the years, the increased search and exchange of information lead to an increase of traffic intensity in todays optical communication networks. Coherent communications, using the amplitude and phase of the signal, reappears as one of the transmission techniques to increase the spectral efficiency and throughput of optical channels. In this context, this work present a study on format conversion of modulated signals using MZI-SOAs, based exclusively on all- optical techniques through wavelength conversion. This approach, when applied in interconnection nodes between optical networks with different bit rates and modulation formats, allow a better efficiency and scalability of the network. We start with an experimental characterization of the static and dynamic properties of the MZI-SOA. Then, we propose a semi-analytical model to describe the evolution of phase and amplitude at the output of the MZI-SOA. The model’s coefficients are obtained using a multi-objective genetic algorithm. We validate the model experimentally, by exploring the dependency of the optical signal with the operational parameters of the MZI-SOA. We also propose an all-optical technique for the conversion of amplitude modulation signals to a continuous phase modulation format. Finally, we study the potential of MZI-SOAs for the conversion of amplitude signals to QPSK and QAM signals. We show the dependency of the conversion process with the operational parameters deviation from the optimal values. The technique is experimentally validated for QPSK modulation.Nos últimos anos, a crescente procura e troca de informação tem levado ao aumento de tráfego nas redes de comunicação óticas atuais. As comunicações coerentes, com recurso à amplitude e fase do sinal, ressurgem como uma das técnicas de transmissão capazes de aumentar a eficiência espectral e o rendimento dos canais óticos. Nesse âmbito, este trabalho apresenta um estudo sobre a conversão de formatos de modulação de sinais, usando técnicas exclusivamente no domínio ótico, através de conversão de comprimento de onda, com base no MZI-SOA. Esta técnica, aplicada em nós óticos que interligam redes óticas com débitos binários distintos, permite uma maior escalabilidade e eficiência da rede. A tese começa por apresentar uma caracterização experimental detalhada das propriedades estáticas e dinâmicas do MZI-SOA. É depois proposto um modelo semi-analítico que descreve a evolução da amplitude e fase do sinal ótico à saída do MZI-SOA. Os coeficientes do modelo são obtidos recorrendo a um algoritmo genético multiobjectivo. O modelo é validado experimentalmente, explorando a dependência do sinal ótico com os parâmetros operacionais do MZI- SOA. Segue-se a proposta de uma técnica de conversão de formato de modulação de amplitude para modulação de fase contínua. Finalmente, é feito um estudo das potencialidades do MZI-SOA para conversão de formato de modulação de amplitude para modulação QPSK e QAM. Mostra-se a dependência da constelação do sinal com o desvio dos parâmetros operacionais, em torno do valor ótimo. A técnica é validada experimentalmente para modulação QPSK

Projector Laser Audio

O sistema descrito utiliza um feixe de luz laser e um conjunto de espelhos rotativos para criar padrões geométricos ópticos. A utilização de outro espelho, acoplado a uma coluna de som, faz vibrar o padrão óptico.info:eu-repo/semantics/publishedVersio

Advanced optical modulation and format conversion

Tese de Doutoramento em Engenharia Eletrotécnica apresentada à Universidade de Aveiro.Nos últimos anos, a crescente procura e troca de informação tem levado ao aumento de tráfego nas redes de comunicação óticas actuais. As comunicações coerentes, com recurso à amplitude e fase do sinal, ressurgem como uma das técnicas de transmissão capazes de aumentar a eficiência espectral e o rendimento dos canais óticos. Nesse âmbito, este trabalho apresenta um estudo sobre a conversão de formatos de modulação de sinais, usando técnicas exclusivamente no domínio ótico, através de conversão de comprimento de onda, com base no MZI-SOA. Esta técnica, aplicada em nós óticos que interligam redes óticas com débitos binàrios distintos, permite uma maior escalabilidade e eficiência da rede. A tese começa por apresentar uma caracterização experimental detalhada das propriedades estáticas e dinámicas do MZI-SOA. É depois proposto um modelo semi-analítico que descreve a evolução da amplitude e fase do sinal ótico à saída do MZI-SOA. Os coeficientes do modelo são obtidos recorrendo a um algoritmo genético multiobjectivo. O modelo é validado experimentalmente, explorando a dependência do sinal ótico com os parâmetros operacionais do MZISOA. Segue-se a proposta de uma técnica de conversão de formato de modulação de amplitude para modulação de fase contínua. Finalmente, é feito um estudo das potencialidades do MZI-SOA para conversão de formato de modulação de amplitude para modulação QPSK e QAM. Mostra-se a depedência da constelação do sinal com o desvio dos parâmetros operacionais, em torno do valor ótimo. A técnica é validada experimentalmente para modulação QPSK.ABSTRACT: Over the years, the increased search and exchange of information lead to an increase of traffic intensity in todays optical communication networks. Coherent communications, using the amplitude and phase of the signal, reappears as one of the transmission techniques to increase the spectral efficiency and throughput of optical channels. In this context, this work present a study on format conversion of modulated signals using MZI-SOAs, based exclusively on alloptical techniques through wavelength conversion. This approach, when applied in interconnection nodes between optical networks with different bit rates and modulation formats, allow a better efficiency and scalability of the network. We start with an experimental characterization of the static and dynamic properties of the MZI-SOA. Then, we propose a semi-analytical model to describe the evolution of phase and amplitude at the output of the MZI-SOA. The model’s coefficients are obtained using a multi-objective genetic algorithm. We validate the model experimentally, by exploring the dependency of the optical signal with the operational parameters of the MZI-SOA. We also propose an all-optical technique for the conversion of amplitude modulation signals to a continuous phase modulation format. Finally, we study the potential of MZI-SOAs for the conversion of amplitude signals to QPSK and QAM signals. We show the dependency of the conversion process with the operational parameters deviation from the optimal values. The technique is experimentally validated for QPSK modulation.Apoio financeiro da Fundação para a Ciência e Tecnologia — FCT através da bolsa SFRH / PROTEC / 50015 / 2009

Versatile Gateway for a Label Loom Machine using Industrial IoT Technologies

Constant search for efficiency and productivity has led to innovation on the factory shop floor, representing an evolution of the current production systems combined with new technologies of industrial automation and information technology. This work presents a versatile gateway for experimental demonstration of Industrial IoT technologies in a loom machine, allowing sensing, monitoring and data acquisition that was not originally available. We have implemented an approach, based on the OPC UA communication protocol for real time applications, and OPC UA to MQTT conversion mechanism. Raspberry Pi’s platform act as an OPC UA server. From the measurements, data stored in a cloud server can be accessed remotely with improved security and visualized from a computer dashboard. One of the conclusions that can be drawn is that the proposed gateway allows data to be stored and monitored from a smartphone application or a computer web interface.info:eu-repo/semantics/publishedVersio

Implementation of a Communication Protocol between a Geo-location Database and TV White Space Devices

Television White Spaces (TVWS) are a spectral opportunity, for secondary users of the spectrum to deliver broadband access to rural areas. Most of the approaches now under test worldwide use a geo-location database to inform secondary users of the available channels, and avoid interference with primary users of the spectrum. The secondary network should follow a approach capable to communicate with a geo-location spectrum database, to store and retrieve information on spectrum occupancy, location of DVB-T broadcast towers and wireless microphones, maximum EIRP of secondary White Space devices (WSDs), sensing activity and other technical parameters. One group from the Internet Engineering Task Force (IETF) is presently working on the definition of a protocol to access white spaces databases – PAWS. The IETF draft protocol was chosen and considered flexible enough to be adapted for the CREW-TV project model and requirements, since it is more comprehensive and less specific on details than other proposals.info:eu-repo/semantics/publishedVersio

Espectrograma de Sinais

Nos tempos actuais o recurso a sistemas cimputorizados é cada vez mais frequente e procurado em todos os ramos de actividade. A crescente utilização de sistemas de reconhecimento de fala, de detecção de sinais e até mesmo de afinação de instrumentos musicais tem levado ao desenvolvimento de novas técnicas nestes variados campos, o que tem originado o interesse cada vez maior por estas tecnologias. Verificando-se uma necessidade de recuros no apoio à instrumentação no laboratório, desenvolveu-se um espectrograma para PC na banda áudio, capaz de adquirir um sinal e fazer a sua análise no tempo e na frequência, com recurso à Transformada Rápida de Fourier (FFT). Para tal desenvolveu-se um programa de computador capaz de aplicar a FFT para posterior visualização dos resultados.info:eu-repo/semantics/publishedVersio