LoRa: applications and validations in complex urban environment LoRa is one of the long range low power wide area network (LPWAN) technologies, it is an ultra-long-range wireless transmission scheme based on spread-spectrum technology adopted and promoted by the American company Semtech. This solution changes the previous compromise between transmission distance and power consumption, and provides users with a simple system that can achieve long distances, long battery life, and large capacity, thereby expanding the sensor network. Although LoRa shows good performance for long distance transmission in the countryside or other spacious environments, its radio signals can be interfered by other signal sources or attenuated by walls, trees, buildings etc.