Model-Driven Development of Aspect-Oriented Software Architectures

[EN] The Model-Driven Development (MDD) paradigm has become widely spread in the last few years due to being based on models instead of source code, and using automatic generation techniques to obtain the final software product. Until now, the most mature methodologies that have been proposed to develop software following MDD are mainly based on functional requirements by following the Object-Oriented Paradigm. Therefore, mature MDD methodologies are required for supporting the code generation from models that specify non-functional requirements. The Aspect-Oriented Software Development (AOSD) approach was created to provide explicit mechanisms for developing non-functional requirements through reusable elements called aspects. Aspect-Oriented Software Architectures (AOSA) emerged to deal with the design of both, functional requirements and non-functional requirements, which opened an important challenge in the software engineering field: the definition of a methodology for supporting the development of AOSAs following the MDD paradigm. This new methodology should allow the code generation from models which specify functional and non-functional requirements. This paper presents a mature approach, called PRISMA, which deals with this challenge. Therefore, this contribution takes a step forward in the area presenting in detail the PRISMA MDD process, which has been applied to generate the code of several real applications of the tele-operated robotics domain. PRISMA MDD approach provides complete support for the development of technology-independent AOSAs, which can be compiled from high-level, aspect-oriented architectural models into different technology platforms and languages following an MDD process. This contribution illustrates how to apply the PRISMA MDD approach through the modelling framework that has been developed to support it, and a case study of a tele-operated robot that has been completely developed using this approach. Finally, the results obtained from the application of PRISMA MDD process to develop applications of the tele-operation domain are analyzed in terms of code generation.The work reported here has been partially sponsored by the Spanish MEC projects (DSDM TIN2008-00889-E and MULTIPLE TIN2009-13838), and MICINN (INNOSEP TIN2009-13849)Pérez Benedí, J.; Ramos Salavert, I.; Carsí Cubel, JÁ.; Costa Soria, C. (2013). Model-Driven Development of Aspect-Oriented Software Architectures. Journal of Universal Computer Science. 19(10):1433-1473. https://doi.org/10.3217/jucs-019-10-143314331473191

System-level assessment of low complexity hybrid precoding designs for massive MIMO downlink transmissions in beyond 5G networks

The fast growth experienced by the telecommunications field during the last few decades has been motivating the academy and the industry to invest in the design, testing and deployment of new evolutions of wireless communication systems. Terahertz (THz) communication represents one of the possible technologies to explore in order to achieve the desired achievable rates above 100 Gbps and the extremely low latency required in many envisioned applications. Despite the potentialities, it requires proper system design, since working in the THz band brings a set of challenges, such as the reflection and scattering losses through the transmission path, the high dependency with distance and the severe hardware constraints. One key approach for overcoming some of these challenges relies on the use of massive/ultramassive antenna arrays combined with hybrid precoders based on fully connected phase-shifter architectures or partially connected architectures, such as arrays of subarrays (AoSAs) or dynamic AoSAs (DAoSAs). Through this strategy, it is possible to obtain very high-performance gains while drastically simplifying the practical implementation and reducing the overall power consumption of the system when compared to a fully digital approach. Although these types of solutions have been previously proposed to address some of the limitations of mmWave/THz communications, a lack between link-level and system-level analysis is commonly verified. In this paper, we present a thorough system-level assessment of a cloud radio access network (C-RAN) for beyond 5G (B5G) systems where the access points (APs) operate in the mmWave/THz bands, supporting multi-user MIMO (MU-MIMO) transmission with massive/ultra-massive antenna arrays combined with low-complexity hybrid precoding architectures. Results showed that the C-RAN deployments in two indoor office scenarios for the THz were capable of achieving good throughput and coverage performances, with only a small compromise in terms of gains when adopting reduced complexity hybrid precoders. Furthermore, we observed that the indoor-mixed office scenario can provide higher throughput and coverage performances independently of the cluster size when compared to the indoor-open office scenario.info:eu-repo/semantics/publishedVersio

Design of terahertz transceiver schemes for ultrahigh-speed wireless communications

Future ultra-high-speed wireless communication systems face difficult challenges due to the fundamental limitations of current technologies operating at microwave frequencies. Supporting high transmission rates will require the use of more spectral resources that are only available at higher frequencies. Within this context, terahertz (THz) communications have been attracting more and more attention, being considered by the research community as one of the most promising research fields on the topic due to the availability of extensive unused bandwidth segments. However, its widespread use is not yet possible due to some obstacles, such as the high propagation losses that occur in this band and the difficulty in designing devices that can effectively perform both transmission and detection tasks. The purpose of this dissertation is to contribute for the solution of both of the aforementioned problems and to propose novel THz transceiver schemes for ultra-high-speed wireless communications. Three main research areas were addressed: device modelling for the THz; index modulation (IM) based schemes for Beyond 5G (B5G) networks and hybrid precoding designs for THz ultra massive (UM) – multiple input multiple output (MIMO) systems. The main contributions of this work include the creation of a new design for a reconfigurable THz filter; the proposal of a precoded generalized spatial modulation scheme for downlink MIMO transmissions in B5G networks; the creation of a low-complexity hybrid design algorithm with a near fully-digital performance for multiuser (MU) mmWave/THz ultra massive MIMO systems that can incorporate different analog architectures; and the system-level assessment of cloud radio access network (C-RAN) deployments based on low-complexity hybrid precoding designs for massive MIMO downlink transmissions in B5G networks. The first contribution is especially suited for the implementation of reconfigurable THz filters and optical modulators, since it is based on a simple design, which transits from situations in which it presents a full transparency to situations where it achieves full opacity. Moreover, this approach can also be used for the implementation of simultaneously transmitting and reflecting (STAR) reconfigurable intelligent surfaces (RIS) which are important for enabling flexible system designs in RIS-assisted networks. The second contribution showed that the implementation of precoding schemes based on generalised spatial modulations is a solution with a considerable potential for future B5G systems, since it can provide larger throughputs when compared to conventional MU-MIMO schemes with identical spectral efficiencies.The last two contributions showed that through the proposed hybrid design algorithm it becomes possible to replace a fully digital precoder/combiner by a fully-connected or even by a partially-connected architecture (array of subarrays and dynamic array of subarrays), while achieving good tradeoffs between spectral efficiency, power consumption and implementation complexity. These proposals are particularly relevant for the support of UM-MIMO in severely hardware constrained THz systems. Moreover, the capability of achieving significant improvements in terms of throughput performance and coverage over typical cellular networks, when considering hybrid precoding‐based C-RAN deployments in two indoor office scenarios at the THz band, was demonstrated.Os futuros sistemas de comunicação sem fios de velocidade ultra-elevada enfrentam desafios difíceis devido às limitações fundamentais das tecnologias atuais que funcionam a frequências de microondas. O suporte de taxas de transmissão altas exigirá a utilização de mais recursos espectrais que só estão disponíveis em frequências mais elevadas. A banda Terahertz (THz) é uma das soluções mais promissoras devido às suas enormes larguras de banda disponíveis no espectro eletromagnético. No entanto, a sua utilização generalizada ainda não é possível devido a alguns obstáculos, tais como as elevadas perdas de propagação que se verificam nesta banda e a dificuldade em conceber dispositivos que possam desempenhar eficazmente as tarefas de transmissão e deteção. O objetivo desta tese de doutoramento, é contribuir para ambos os problemas mencionados anteriormente e propor novos esquemas de transcetores THz para comunicações sem fios de velocidade ultra-elevada. Três grandes áreas de investigação foram endereçadas, contribuindo individualmente para um todo: a modelação do dispositivo para o THz; esquemas baseados em modulações de índice (IM) para redes pós-5G (B5G) e desenhos de pré-codificadores híbridos para sistemas THz MIMO ultra-massivos. As principais contribuições deste trabalho incluem a criação de um novo design para um filtro THz reconfigurável; a proposta de uma nova tipologia de modulação espacial generalizada pré-codificada para transmissões MIMO de ligação descendente para redes B5G; a criação de um algoritmo de design híbrido de baixa complexidade com desempenho quase totalmente digital para sistemas MIMO multi-utilizador (MU) mmWave/THz ultra massivos que podem incorporar diferentes arquiteturas analógicas e a avaliação das implementações da rede de acesso de rádio na nuvem (C-RAN) com base em designs de pré-codificação híbridos de baixa complexidade para transmissões MIMO de ligação descendente massivas em redes B5G. A primeira contribuição é especialmente adequada para a implementação de filtros THz reconfiguráveis e moduladores óticos, uma vez que se baseia numa concepção mais simples, que transita de situações em que apresenta uma transparência total para situações em que atinge uma opacidade total. Para além disso, esta abordagem também pode ser utilizada para a implementação de superfícies inteligentes reconfiguráveis (RIS) de transmissão e reflexão simultânea (STAR). A segunda contribuição mostrou que a implementação de esquemas de pré-codificação baseados em modulações espaciais generalizadas é uma solução com um potencial considerável para futuros sistemas B5G, uma vez que permite alcançar maiores ganhos em termos de débito binário quando comparado com esquemas convencionais MU-MIMO com eficiências espectrais idênticas. As duas últimas contribuições mostraram que através do algoritmo proposto torna-se possível substituir a utilização de uma arquitectura totalmente digital por uma arquitetura totalmente conectada ou mesmo por uma arquitetura parcialmente conectada (arrays de subarrays e arrays dinâmicos de subarrays), conseguindo-se bons tradeoffs entre eficiência espectral, consumo de energia e complexidade de implementação. Estas propostas são particularmente relevantes para dar suporte a sistemas THz UM-MIMO com restrições severas ao nível de hardware. Demonstrou-se também a capacidade de se alcançar melhorias significativas em termos de débito binário e cobertura em relação a redes celulares típicas, considerando dois cenários na banda THz

Low complexity hybrid precoding designs for multiuser mmWave/THz ultra massive MIMO Systems

Millimeter-wave and terahertz technologies have been attracting attention from the wireless research community since they can offer large underutilized bandwidths which can enable the support of ultra-high-speed connections in future wireless communication systems. While the high signal attenuation occurring at these frequencies requires the adoption of very large (or the so-called ultra-massive) antenna arrays, in order to accomplish low complexity and low power consumption, hybrid analog/digital designs must be adopted. In this paper we present a hybrid design algorithm suitable for both mmWave and THz multiuser multiple-input multiple-output (MIMO) systems, which comprises separate computation steps for the digital precoder, analog precoder and multiuser interference mitigation. The design can also incorporate different analog architectures such as phase shifters, switches and inverters, antenna selection and so on. Furthermore, it is also applicable for different structures, namely fully-connected structures, arrays of subarrays (AoSA) and dynamic arrays of subarrays (DAoSA), making it suitable for the support of ultra-massive MIMO (UM-MIMO) in severely hardware constrained THz systems. We will show that, by using the proposed approach, it is possible to achieve good trade-offs between spectral efficiency and simplified implementation, even as the number of users and data streams increases.info:eu-repo/semantics/publishedVersio

A GAIN-SCHEDULED CONTROL SCHEME FOR IMPROVED MANEUVERABILITY AND POWER EFFICIENCY OF UNDERWATER GLIDERS

Underwater gliders are a relatively new type of low-power, long duration underwater vehicle that use changes in buoyancy to propel themselves forward. They are widely used today for oceanographic research, and a number of theoretical control schemes have been derived over the years. However, despite their nonlinear dynamics that evolve as a function of their environment and operating conditions, most fielded gliders use linear control methods, such as static-gain proportional-integral (PI) or proportional-integral-derivative (PID) compensators for motion control, which can significantly limit vehicle performance. This thesis develops an alternative approach to underwater glider control that employs control system gain-scheduling to improve vehicle performance and efficiency over a wider range of operating conditions as compared to static or fixed-gain approaches. The primary contribution of this thesis is the development of a practical gain-scheduling procedure using linearized models of the decoupled pitch and yaw dynamics of the vehicle. This methodology improves on the current fixed-gain topologies used on fielded gliders today, while being straightforward and cost-effective to implement. In this thesis, the development of a nonlinear dynamical model of a Slocum glider using computer-aided design (CAD) and computational fluid dynamics (CFD) simulations was also carried out to support the high-fidelity characterization of the controller topologies. A nonlinear numerical simulation of the Slocum glider was developed in Matlab and was used to assess the performance improvements and the increased robustness of the gain-scheduled PID method to a standard fixed-gain PID approach

Distinguishing a phonological encoding disorder from Apraxia of Speech in individuals with aphasia by using EEG

As we speak, various processes take place in our brains. We find the word, find and organize the speech sounds and program the movements for speech. A stroke may cause impairment at any of these processes. Usually, multiple processes are affected. Existing methods to distinguish a disorder in finding and organizing speech sounds (phonological encoding) from an impairment in programming the articulation (Apraxia of Speech) are not optimal. In this thesis, it was studied whether EEG, measuring small changes in electric brain activity with electrodes that are placed on the scalp, can be used for this purpose. A protocol was developed to trace the processes of speech production, which was successfully tested in a group of younger and one of older neurologically healthy adults. In the younger and older adults, the processes were registered at the same electrodes on the scalp, but the time window and the waveform of the processes differed. In individuals with a phonological encoding disorder and those with Apraxia of Speech the disordered processes could not be identified, because the severity of the impairment in the groups varied. Their impaired processes differed from those in neurologically healthy individuals. Also, because of their disorder in the previous stage, the programming of the articulation was different in individuals with a phonological encoding disorder. The protocol can distinguish a phonological encoding disorder from Apraxia of Speech due to differences in the EEG data (relative to neurologically healthy participants) that only were observed during programming movements for speech

Avaliação do mapa sonoro de tráfego veicular no município de Natal/RN

Sound pollution is already considered by the World Health Organization (WHO) the second largest cause of global pollution. In a general context, urban development was accompanied by the accelerated growth of cities and the increased circulation of motor vehicles, causing higher levels of noise pollution. Urban environments present complex acoustic scenarios and studies about them need to consider the impact of several sound sources. Computational models become facilitators, evaluating possible solutions, since they enable fast calculations, analyzes and reports. With this feature, it is possible to know the sound pressure levels at any point in a modeled area, through direct reading on the sound map. The research problem appointed in this dissertation is: How traffic noise can be spatialized in Natal street system? The hypothesis points to sound pressure levels above those recommended by legislation in arterial and "secondary" streets of Natal/RN. Therefore, this research aims to evaluate the quality of the sound environment and its relation with the road network in Natal / RN, by mapping traffic noise with a computational model assistance. We gather and analyze traffic data, acoustic and physical-environmental conditioning maps as methodological procedures. Then, sound maps were processed through computer simulation software. These maps were calibrated based on quantitative acoustic measurement data on site. As results, it was verified that the vehicular flow follows a pattern of growth based on variables such as width and length of the track. There is a strong correlation between vehicle flow and sound pressure levels. The average equivalent level of noise (LAeq, 7-22h) in t Natal is 75.4% higher than the 55dB recommended by NBR 10151 (ABNT, 2000) for residential use and excess 15.3% on the 65dB World Health Organization recommendation (WHO, 1999). In the marginal street range (from curb to 100m) 95.8% extrapolate the 65dB in arterial pathways. Finally, from the diagnosis of the attributes involved, the guidelines for planning in the environmental acoustics were elaborated, in order to minimize the noise impact.A poluição sonora já é considerada, pela Organização Mundial de Saúde (OMS) a segunda maior causa de poluição no mundo. Num contexto geral, o desenvolvimento urbano foi acompanhado pelo crescimento acelerado das cidades e pelo aumento da circulação de veículos automotores, causando maiores níveis de poluição sonora. Os ambientes urbanos apresentam cenários acústicos complexos e seus estudos precisam considerar a participação de várias fontes sonoras. Ao avaliar possíveis soluções, os modelos computacionais se tornam facilitadores, uma vez que possibilitam a realização de rápidos cálculos, análises e relatórios. Com tal recurso, é possível conhecer os níveis de pressão sonora em qualquer ponto de uma área modelada, por meio de leitura direta no mapa sonoro. O problema da pesquisa consistiu em: de que forma se espacializa o ruído de tráfego no sistema viário no município de Natal? Para isso, levanta-se como hipótese que no município de Natal/RN, as vias definidas como arteriais e coletoras encontram-se em níveis de pressão sonora acima dos recomendados pela legislação. Portanto, esta pesquisa tem como objetivo geral avaliar a qualidade do ambiente sonoro e sua relação com a malha viária no município de Natal/RN, a partir do mapeamento do ruído de tráfego com auxílio de modelo computacional. Os procedimentos metodológicos consistiram na coleta e análise dos dados de tráfego, acústicos e mapas dos condicionantes físico-ambientais. Em seguida, foram elaborados os mapas sonoros processados através do software de simulação computacional. Tais mapas foram calibrados com base em dados quantitativos de medição acústica in loco. Como resultados, constatou-se que o fluxo veicular segue um padrão de crescimento com base em variáveis como largura e comprimento da via. E que existe forte correlação entre o fluxo veicular e os níveis de pressão sonora. O nível equivalente médio de ruído (LAeq, 7-22h) no município do Natal/RN apresenta 75.4% acima dos 55dB recomendado pela NBR 10151 (ABNT, 2000) para uso misto residencial e 15.3% excedente a 65dB, recomendado pela Organização Mundial de Saúde (OMS, 1999). Na faixa lindeira (meio fio a 100m) 95.8% extrapolam os 65dB em vias arteriais. Por fim, a partir do diagnóstico dos atributos envolvidos, elaboraram-se as diretrizes para planejamento na acústica ambiental, com a finalidade de minimizar o impacto em relação ao ruído

Avaliação do mapa sonoro de tráfego veicular no município de Natal/RN

Sound pollution is already considered by the World Health Organization (WHO) the second largest cause of global pollution. In a general context, urban development was accompanied by the accelerated growth of cities and the increased circulation of motor vehicles, causing higher levels of noise pollution. Urban environments present complex acoustic scenarios and studies about them need to consider the impact of several sound sources. Computational models become facilitators, evaluating possible solutions, since they enable fast calculations, analyzes and reports. With this feature, it is possible to know the sound pressure levels at any point in a modeled area, through direct reading on the sound map. The research problem appointed in this dissertation is: How traffic noise can be spatialized in Natal street system? The hypothesis points to sound pressure levels above those recommended by legislation in arterial and "secondary" streets of Natal/RN. Therefore, this research aims to evaluate the quality of the sound environment and its relation with the road network in Natal / RN, by mapping traffic noise with a computational model assistance. We gather and analyze traffic data, acoustic and physical-environmental conditioning maps as methodological procedures. Then, sound maps were processed through computer simulation software. These maps were calibrated based on quantitative acoustic measurement data on site. As results, it was verified that the vehicular flow follows a pattern of growth based on variables such as width and length of the track. There is a strong correlation between vehicle flow and sound pressure levels. The average equivalent level of noise (LAeq, 7-22h) in t Natal is 75.4% higher than the 55dB recommended by NBR 10151 (ABNT, 2000) for residential use and excess 15.3% on the 65dB World Health Organization recommendation (WHO, 1999). In the marginal street range (from curb to 100m) 95.8% extrapolate the 65dB in arterial pathways. Finally, from the diagnosis of the attributes involved, the guidelines for planning in the environmental acoustics were elaborated, in order to minimize the noise impact.A poluição sonora já é considerada, pela Organização Mundial de Saúde (OMS) a segunda maior causa de poluição no mundo. Num contexto geral, o desenvolvimento urbano foi acompanhado pelo crescimento acelerado das cidades e pelo aumento da circulação de veículos automotores, causando maiores níveis de poluição sonora. Os ambientes urbanos apresentam cenários acústicos complexos e seus estudos precisam considerar a participação de várias fontes sonoras. Ao avaliar possíveis soluções, os modelos computacionais se tornam facilitadores, uma vez que possibilitam a realização de rápidos cálculos, análises e relatórios. Com tal recurso, é possível conhecer os níveis de pressão sonora em qualquer ponto de uma área modelada, por meio de leitura direta no mapa sonoro. O problema da pesquisa consistiu em: de que forma se espacializa o ruído de tráfego no sistema viário no município de Natal? Para isso, levanta-se como hipótese que no município de Natal/RN, as vias definidas como arteriais e coletoras encontram-se em níveis de pressão sonora acima dos recomendados pela legislação. Portanto, esta pesquisa tem como objetivo geral avaliar a qualidade do ambiente sonoro e sua relação com a malha viária no município de Natal/RN, a partir do mapeamento do ruído de tráfego com auxílio de modelo computacional. Os procedimentos metodológicos consistiram na coleta e análise dos dados de tráfego, acústicos e mapas dos condicionantes físico-ambientais. Em seguida, foram elaborados os mapas sonoros processados através do software de simulação computacional. Tais mapas foram calibrados com base em dados quantitativos de medição acústica in loco. Como resultados, constatou-se que o fluxo veicular segue um padrão de crescimento com base em variáveis como largura e comprimento da via. E que existe forte correlação entre o fluxo veicular e os níveis de pressão sonora. O nível equivalente médio de ruído (LAeq, 7-22h) no município do Natal/RN apresenta 75.4% acima dos 55dB recomendado pela NBR 10151 (ABNT, 2000) para uso misto residencial e 15.3% excedente a 65dB, recomendado pela Organização Mundial de Saúde (OMS, 1999). Na faixa lindeira (meio fio a 100m) 95.8% extrapolam os 65dB em vias arteriais. Por fim, a partir do diagnóstico dos atributos envolvidos, elaboraram-se as diretrizes para planejamento na acústica ambiental, com a finalidade de minimizar o impacto em relação ao ruído