ITED 3 – evolução nas regras técnicas de projeto e instalação de infraestruturas de telecomunicações em edifícios

Dez anos após a publicação da primeira edição do Manual ITED, entrou em vigor em 2015 a terceira edição deste manual, contendo as novas regras técnicas aplicadas ao projeto e instalação de Infraestruturas de telecomunicações em edifícios, denominadas por ITED 3.info:eu-repo/semantics/publishedVersio

Public mobile wideband networks interference impact assessment on railways GSM-R network

This paper presents a field study relating to the impact that public operator cellular networks such as UMTS (Universal Mobile Telecommunication System), LTE (Long-Term Evolution), and 5G-NR (5G - New Radio) have on railway GSM-R (Global System for Mobile Communications – Railway) networks. The validation of the interference calculation relied on actual network measurements taken along railway lines using a dedicated probe. Emissions from public networks, in some scenarios, have been shown to affect GSM-R networks to a large extent. The developed algorithm is currently being used in real GSM-R network planning to mitigate this negative effect on base station coverage and service performance.info:eu-repo/semantics/publishedVersio

Repetidor para ambientes interiores em CDMA2000

Esta comunicação descreve o desenvolvimento do protótipo de um repetidor para ambientes interiores, que será usado com a tecnologia CDMA2000 na faixa dos 460 MHz. O protótipo, que fica intercalado entre 2 antenas, consiste num módulo activo que efectua amplificação bi-direccional. Foram realizadas medidas de campo com este sistema, mostrando-se uma clara melhoria de cobertura.info:eu-repo/semantics/publishedVersio

Effect of Rare Earth Ions on the Properties of Composites Composed of Ethylene Vinyl Acetate Copolymer and Layered Double Hydroxides

BACKGROUND: The study on the rare earth (RE)-doped layered double hydroxides (LDHs) has received considerable attention due to their potential applications in catalysts. However, the use of RE-doped LDHs as polymer halogen-free flame retardants was seldom investigated. Furthermore, the effect of rare earth elements on the hydrophobicity of LDHs materials and the compatibility of LDHs/polymer composite has seldom been reported. METHODOLOGY/PRINCIPAL FINDINGS: The stearate sodium surface modified Ni-containing LDHs and RE-doped Ni-containing LDHs were rapidly synthesized by a coprecipitation method coupled with the microwave hydrothermal treatment. The influences of trace amounts of rare earth ions La, Ce and Nd on the amount of water molecules, the crystallinity, the morphology, the hydrophobicity of modified Ni-containing LDHs and the adsorption of modifier in the surface of LDHs were investigated by TGA, XRD, TEM, contact angle and IR, respectively. Moreover, the effects of the rare earth ions on the interfacial compatibility, the flame retardancy and the mechanical properties of ethylene vinyl acetate copolymer (EVA)/LDHs composites were also explored in detail. CONCLUSIONS/SIGNIFICANCE: S-Ni₀.₁MgAl-La displayed more uniform dispersion and better interfacial compatibility in EVA matrix compared with other LDHs. Furthermore, the S-Ni₀.₁MgAl-La/EVA composite showed the best fire retardancy and mechanical properties in all composites

LoRaWAN and urban waste management - A trial

The city of Lisbon, as any other capital of a European country, has a large number of issues regarding managing waste and recycling containers spread throughout the city. This document presents the results of a study promoted by the Lisbon City Council for trialing LPWAN (Low-Power Wide-Area Network) technology for the waste management vertical under the Lisbon Smart City initiative. Current waste management is done using GSM (Global System for Mobile communications) sensors, and the municipality aims to use LPWAN in order to improve range and reduce costs and provisioning times when changing the communications provider. After an initial study, LoRa (Long Range) and LoRAWAN (LoRa Wide Area Network) as its network counterpart, were selected as the LPWAN technology for trials considering several use cases, exploring multiple distances, types of recycling waste containers, placements (underground or surface) and kinds of commercially available waste level measurement LoRa sensors. The results showed that the underground waste containers proved to be, as expected, the most difficult to operate correctly, where the container itself imposed attenuation levels of 26 dB on the LoRa link budget. The successful results were used to promote the deployment of a city-wide LoRa network, available to all the departments inside the Lisbon City Council. Considering the network capacity, the municipality also decided to make the network freely available to citizens.info:eu-repo/semantics/publishedVersio

Railways communications propagation prediction over irregular terrain using longley-rice model

This paper presents the evaluation results of the radio signal propagation prediction using Longley-Rice model in railways installed in rural areas with significant variation of propagation path and terrain profiles. The prediction results were compared with measurement acquired by installing several CW emitters along the railway and reception equipment installed on a rolling stock. In addition, the results were also compared with the prediction based on Okumura-Hata model. The obtained results prove Longley-Rice suitability for railways communication prediction on irregular terrain, achieving better results than the Okumura-Hata model.info:eu-repo/semantics/publishedVersio

A performance measurement platform for C-ITS over 5G

This paper aims to present a new performance measurement tool dedicated to mobile cellular networks, focussed on the new C-ITS applications and challenges. Called ISEL QoS-Network Performance Evaluation (IQ-NPE), developed under the European Union 5G-MOBIX project, it is a measurement performance tool that is able to extract a wide range of performance parameters at different levels: radio, network layers and application. This is a step further when comparing with classical tools, based on mobile terminals, because C-ITS applications take advantage of cellular modems using Multiple Input Multiple Output (MIMO) advanced systems, due to available space offered by vehicles. IQ-NPE is designed to test classical alongside with the new C-ITS applications (ITS-G5 based) performance running at the Multi-access/Mobile Edge Computing (MEC) node in the new 5G architecture. All the collected data can be exported, as integrated performance data, to further be analysed using business intelligence tools. Thus, this paper presents the IQ-NPE general architecture, its main components, probes (units composed by hardware and software subsystems), together with configuration input and output examples.info:eu-repo/semantics/publishedVersio

Optimizing Propagation Models on Railway Communications Using Genetic Algorithms

AbstractAlthough the Okumura-Hata prediction model has been a widely used model to estimate radio network coverage, its application in railways environment requires calibration. The objective of this work is to present Genetic Algorithms as a solution in optimizing propagation models, proving that it can be used for optimizing the Okumura-Hata model on railway communications in order to improve its prediction of radio coverage.Several tests were carried out using different conditions allowing to establish the conditions that maximize the gain of the algorithm for this particular problem. The algorithm was applied to training samples and the resulting parameters were applied to different scenarios, showing improvements in the prediction results

On the use of okumura-hata propagation model on railway communications

Although Okumura–Hata prediction model has been a widely used model to estimate radio network coverage, its application in railways environment requires validation and additional studies. This paper presents the main results on a study based on measurements campaigns, and identifies significant differences in parameters that characterize the radio propagation in railways environment, for the 900MHz band. Both the propagation slope and standard deviation measured values are presented in this work. For validation, the developed model setup was used in the radio planning process, setting a live Global System for Mobile Communications-Railway pilot network, operating in Portugal.info:eu-repo/semantics/publishedVersio