Sensing is an activity of paramount importance for smart cities. The coverage of large areas based on reduced infrastructure and low energy consumption is desirable. In this context, Low Power Wide Area Networks (LPWAN) play an important role. In this paper, we investigate LoRa, a low power technology offering large coverage, but low transmission rates. Radio range and data rate are tunable by using different spreading factors and coding rates, which are configuration parameters of the LoRa PHY layer. LoRa can cover large areas but variations in the environment affect link quality. This work studies the propagation of LoRa signals in forest, urban, and suburban vehicular environments. Besides being environments with variable propagation conditions, we evaluate scenarios with node mobility. To char
This work presents the hardware and software characteristics of the environmental surveillance radiological network that has been installed around the nuclear power station of Almaraz (Spain). A description is given of the program RADLINE which allows radiological data to be logged in real time, and a study is made of the operativity of the network and the methodology followed in establishing the radiological pre-alert and alert levels.
Serviços baseados em localização permitem o monitoramento de pessoas ou áreas específicas. Através do acompanhamento da sua localização, é possível auxiliar o resgate de pessoas perdidas ou acidentadas em ambientes naturais. No entanto, as redes sem-fio em áreas de densa vegetação, neste caso, a Mata Atlântica, implicam desafios relacionados com mobilidade e conectividade. Este trabalho compara o desempenho em termos de alcance, potência do sinal, taxa de perda e atraso em enlaces implementados usando as tecnologias LoRa, IEEE 802.11g e ZigBee no Parque Nacional da Serra dos Órgãos. A comparação destas métricas permite distinguir as limitações de cada tecnologia que podem influenciar na disseminação de alertas. Os resultados mostram que o alcance máximo da LoRa é 3 vezes maior do que o IEEE 802.11g e 6 vezes maior do que o ZigBee, com potência do sinal recebido menor que as duas tecnologias, em média 21,67% e 26,15%, respectivamente.
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