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- 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.
- 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.