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- Automatic tunning of Okumura-Hata model on railway communicationsPublication . Beire, Ana Rita; Cota, Nuno; Pinheiro Pita, Helder Jorge; Rodrigues, AntónioThis paper presents the Genetic Algorithms (GA) as an efficient solution for the Okumura-Hata prediction model tuning on railways communications. A method for modelling the propagation model tuning parameters was presented. The algorithm tuning and validation were based on real networks measurements carried out on four different propagation scenarios and several performance indicators were used. It was shown that the proposed GA is able to produce significant improvements over the original model. The algorithm developed is currently been used on real GSM-R network planning process for an enhanced resources usage.
- LoRaWAN and urban waste management - A trialPublication . Cruz, Nuno; Cota, Nuno; Tremoceiro, JoãoThe 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.
- Railways communications propagation prediction over irregular terrain using longley-rice modelPublication . Prior, Pedro; Cota, NunoThis 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.
- On the use of okumura-hata propagation model on railway communicationsPublication . Cota, Nuno; Serrador, António; Vieira, Pedro; Beire, Ana Rita; Rodrigues, AntonioAlthough 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.
- Optimizing propagation models on railway communications using genetic algorithmsPublication . Beire, Ana Rita; Pinheiro Pita, Helder Jorge; Cota, NunoAlthough 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.
- A performance measurement platform for C-ITS over 5GPublication . Serrador, António; Mendes, Carlos; Datia, Nuno; Cota, Nuno; Cruz, Nuno; Beire, Ana R.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.
- Public mobile wideband networks interference impact assessment on railways GSM-R networkPublication . Rouco, André; Cota, Nuno; Beire, Ana Rita; Serrador, AntónioThis 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.
- Repetidor para ambientes interiores em CDMA2000Publication . Feiteira, Filipe; Assunção, João; Cota, Nuno; Fortes, Fernando; Silva, Henrique; Mendes, CarlosEsta 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.