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- 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.