LTE-R : comunicações móveis ferroviárias de banda larga

Dissertação para obtenção do grau de mestre em Engenharia de Eletrónica e TelecomunicaçõesAssistimos atualmente em Portugal, mas também no resto do mundo, a projetos de renovação dos sistemas de telecomunicações móveis das ferrovias. A tecnologia que correntemente está a ser instalada em Portugal é o GSM-R, mas apesar de todas as inúmeras qualidades que esta tecnologia oferece, já se fala atualmente nas suas limitações. Assim, já há alguns anos que se procura pelo seu substituto e das opções que existem uma delas sobressai, o LTE-R. Neste projeto, procura-se investigar o LTE-R e verificar a sua adequação às necessidades cada vez mais exigentes das ferrovias. O estudo do GSM-R e das comunicações móveis ferroviárias foi realizado. Neste verificou-se que a questão da segurança, da interoperabilidade e da sinalização ferroviária são fatores chave que qualquer tecnologia de comunicações móveis ferroviárias deve conseguir responder. A solução na europa para cumprir com esses objetivos é o ERTMS/ETCS, assim qualquer tecnologia de comunicações móveis ferroviárias tem obrigatoriamente de implementar as soluções definidas nestes dois sistemas. Os requisitos específicos das telecomunicações ferroviárias são extensos. Eles incluem requisitos de cobertura de 95% em cada troço de 100m, níveis de sinal de -95 dBm, tempos de estabelecimento de chamada de emergência inferiores a dois segundos assim como uma extensa lista de requisitos funcionais que o LTE-R tem de conseguir garantir. A enfase do estudo encontra-se na interface rádio do LTE-R nesse sentido são efetuadas simulações do seu desempenho em condições de ambientes ferroviários, incluindo casos em que as velocidades praticadas atingem os 500km/h. Com dados de medidas rádio de um levantamento realizado numa linha férrea, são realizados estudos de cobertura e capacidade que permitem aferir a validade da utilização do LTE-R em ambientes ferroviários.We are currently witnessing in Portugal, but also in the rest of the world, projects for the renewal of railroad mobile telecommunications systems. The technology currently being installed in Portugal is GSM-R, but despite all the numerous qualities that this technology offers, it is currently being talked about its limitations. So, for some years now, we have been looking for a replacement, of which there is one of them that stands out, the LTE-R. In this project, we seek to investigate the LTE-R, to verify its suitability to the increasingly demanding needs of the railways. The study of GSM-R and rail mobile communications was carried out. It was found that the issue of safety, interoperability and railway signalling are key factors that any rail mobile communications technology must be able to address. The solution in Europe to meet these objectives is ERTMS / ETCS, so any rail mobile communications technology must implement the solutions defined in these two systems. Specific requirements for rail mobile telecommunications are extensive they include 95% coverage requirements on each 100m section, -95dBm signal levels, emergency call establishment times of less than two seconds as well as an extensive list of functional requirements that LTE-R must guarantee. The emphasis of the study is on the LTE-R radio interface. Simulations of its performance are performed under conditions of railway environments, including cases where the speeds practiced reach 500km/h. With radio measurement data from a railway survey, coverage and capacity studies are performed to assess the validity of using LTE-R in railway environments.N/

Mobile Broadband Scaling and Enhancement for Fast Moving Trains

Internet is an important part of our life, whether traveling or at home. The broadband services available at home are reliable and are usually at constant speed. The people traveling especially in fast moving trains are at higher mobility and may be moving in areas of less connectivity, and providing a reliable service to them is a challenging task. One possible solution to this is to provide communication through an on-board Wi-Fi, which takes services from a central Wi-Fi situated in the middle of the train, which is connected to cellular radio service long-term evolution for railways. The network consists of LTE-R which is dedicated for railway communication only, a public mobile network, which supports LTE-R in the areas of no coverage and high traffic conditions and a public safety network in emergency conditions. The work is verified with the help of simulations on MATLAB, considering different traffic scenarios. The BSs placed at a distance of 2.5 Km and antenna height used is 45 m are equipped with 3G and 4G interfaces, a universal mobile telecommunications services (UMTS) and radio access network (RAN). The UMTS interface is used for voice services and handover when spectrum available in the next cell is less

Constructed wetlands: Treatment of concentrated storm water runoff (part A)

The aim of this research was to assess the treatment efficiencies for gully pot liquor of experimental vertical- flow constructed wetland filters containing Phragmites australis (Cav.) Trin. ex Steud. (common reed) and filter media of different adsorption capacities. Six out of 12 filters received inflow water spiked with metals. For 2 years, hydrated nickel and copper nitrate were added to sieved gully pot liquor to simulate contaminated primary treated storm runoff. For those six constructed wetland filters receiving heavy metals, an obvious breakthrough of dissolved nickel was recorded after road salting during the first winter. However, a breakthrough of nickel was not observed, since the inflow pH was raised to eight after the first year of operation. High pH facilitated the formation of particulate metal compounds such as nickel hydroxide. During the second year, reduction efficiencies of heavy metal, 5-days at 20°C N-Allylthiourea biochemical oxygen demand (BOD) and suspended solids (SS) improved considerably. Concentrations of BOD were frequently �20 mg/L. However, concentrations for SS were frequently �30 mg/L. These are the two international thresholds for secondary wastewater treatment. The BOD removal increased over time due to biomass maturation, and the increase of pH. An analysis of the findings with case-based reasoning can be found in the corresponding follow-up paper (Part B)

Land cover mapping at very high resolution with rotation equivariant CNNs: towards small yet accurate models

In remote sensing images, the absolute orientation of objects is arbitrary. Depending on an object's orientation and on a sensor's flight path, objects of the same semantic class can be observed in different orientations in the same image. Equivariance to rotation, in this context understood as responding with a rotated semantic label map when subject to a rotation of the input image, is therefore a very desirable feature, in particular for high capacity models, such as Convolutional Neural Networks (CNNs). If rotation equivariance is encoded in the network, the model is confronted with a simpler task and does not need to learn specific (and redundant) weights to address rotated versions of the same object class. In this work we propose a CNN architecture called Rotation Equivariant Vector Field Network (RotEqNet) to encode rotation equivariance in the network itself. By using rotating convolutions as building blocks and passing only the the values corresponding to the maximally activating orientation throughout the network in the form of orientation encoding vector fields, RotEqNet treats rotated versions of the same object with the same filter bank and therefore achieves state-of-the-art performances even when using very small architectures trained from scratch. We test RotEqNet in two challenging sub-decimeter resolution semantic labeling problems, and show that we can perform better than a standard CNN while requiring one order of magnitude less parameters

Filter for detecting and isolating faults for a nonlinear system

In the paper the problem of detecting and isolating multiple faults for nonlinear systems is considered. A strategy of state filtering is derived in order to detect and isolate multiple faults which appear simultaneously or sequentially in a discrete time nonlinear systems with unknown inputs. For the considered system for which a fault isolation condition is fulfilled the proposed method can isolate p simultaneous faults with at least p+q output measurements, where q is the number of unknown inputs or disturbances. A reduced output residual vector of dimension p+q is generated and the elements of this vector are decoupled in a way that each element of the vector is associated with only one fault or unmeasured input

First Light with ALES: A 2-5 Micron Adaptive Optics Integral Field Spectrograph for the LBT

Integral field spectrographs are an important technology for exoplanet imaging, due to their ability to take spectra in a high-contrast environment, and improve planet detection sensitivity through spectral differential imaging. ALES is the first integral field spectrograph capable of imaging exoplanets from 3-5$\mu$m, and will extend our ability to characterize self-luminous exoplanets into a wavelength range where they peak in brightness. ALES is installed inside LBTI/LMIRcam on the Large Binocular Telescope, taking advantage of existing AO systems, camera optics, and a HAWAII-2RG detector. The new optics that comprise ALES are a Keplerian magnifier, a silicon lenslet array with diffraction suppressing pinholes, a direct vision prism, and calibration optics. All of these components are installed in filter wheels making ALES a completely modular design. ALES saw first light at the LBT in June 2015.Comment: 13 pages, 9 figures, Proc. SPI

Detection of replay attacks in cyber-physical systems using a frequency-based signature

This paper proposes a frequency-based approach for the detection of replay attacks affecting cyber-physical systems (CPS). In particular, the method employs a sinusoidal signal with a time-varying frequency (authentication signal) into the closed-loop system and checks whether the time profile of the frequency components in the output signal are compatible with the authentication signal or not. In order to carry out this target, the couplings between inputs and outputs are eliminated using a dynamic decoupling technique based on vector fitting. In this way, a signature introduced on a specific input channel will affect only the output that is selected to be associated with that input, which is a property that can be exploited to determine which channels are being affected. A bank of band-pass filters is used to generate signals whose energies can be compared to reconstruct an estimation of the time-varying frequency profile. By matching the known frequency profile with its estimation, the detector can provide the information about whether a replay attack is being carried out or not. The design of the signal generator and the detector are thoroughly discussed, and an example based on a quadruple-tank process is used to show the application and effectiveness of the proposed method.Peer ReviewedPostprint (author's final draft

Magnetic compressibility and ion-temperature-gradient-driven microinstabilities in magnetically confined plasmas

The electromagnetic theory of the strongly driven ion-temperature-gradient (ITG) instability in magnetically confined toroidal plasmas is developed. Stabilizing and destabilizing effects are identified, and a critical $\beta_{e}$ (the ratio of the electron to magnetic pressure) for stabilization of the toroidal branch of the mode is calculated for magnetic equilibria independent of the coordinate along the magnetic field. Its scaling is $\beta_{e}\sim L_{Te}/R,$ where $L_{Te}$ is the characteristic electron temperature gradient length, and $R$ the major radius of the torus. We conjecture that a fast particle population can cause a similar stabilization due to its contribution to the equilibrium pressure gradient. For sheared equilibria, the boundary of marginal stability of the electromagnetic correction to the electrostatic mode is also given. For a general magnetic equilibrium, we find a critical length (for electromagnetic stabilization) of the extent of the unfavourable curvature along the magnetic field. This is a decreasing function of the local magnetic shear

Enhanced Trellis Coded Multiple Access (ETCMA)

We propose an enhanced version of trellis coded multiple access (TCMA), an overloaded multiple access scheme that outperforms the original TCMA in terms of achieved spectral efficiency. Enhanced TCMA (ETCMA) performs simultaneous transmission of multiple data streams intended for users experiencing similar signal-to-noise ratios and can be employed both in the uplink and in the downlink of wireless systems, thus overcoming one of the main limitations of TCMA. Thanks to a new receiver algorithm, ETCMA is capable of delivering a significantly higher spectral efficiency. We show that ETCMA approaches the capacity of the Additive White Gaussian Noise channel for a wide range of signal-to-noise ratios.Comment: 5 pages, 5 figure