LoRa: applications and validations in complex urban environment

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. This study focuses on transmission performance of LoRa technology and performed by measured data at different places with different parameters in complex urban environments. Meanwhile, we combined the LoRa modules with the device Industruino IND.I/O D21G (a Arduino-compatible equivalent of a programmable logic controller) and Ethernet module to get some specific performances. In the beginning, we did some preliminary experiments to be thoroughly familiar with the Arduino (an open-source electronics platform based on easy-to-use hardware and software) environment. The first one is to connect one button with the D21G board, then we uploaded the corresponding program code to the board via Arduino to implement the specific performance as follows. When we press the button, the liquid crystal display (LCD) will turn on and when we raise hand the LCD will turn off. The second performance that we implemented is when we press the button, the LCD will keep bright until we press the button again. Then we move on to three buttons, with a specific sequence to control the LCD “on” and “off”. Then we tried to observe the serial port values from the webpage by using the Ethernet module and finally we did it. After all the works which are mentioned above are finished, we start to perform the validations by evaluating the performances of LoRa in complex urban environments. More specifically,we set up two LoRa modules as the transmitters and another LoRa module as the receiver. The first transmitter is placed in the office room while the other one is placed on the balcony, transmitting the same data length each time. Then we went outside and hang out and measured the received packets in 14 different places around the transmitters. Finally, the system’s performance of coverage and packet loss rate are analyzed. Since the current popular channel models can not capture signal attenuation well, we would like to focus on the empirical model of Okumura-Hata (analyzing path-loss characteristics based on a large amount of experimental data), which is so far widely used for LoRa. Its estimates is very close to our measurements. By examining a real dataset with tens of thousands of samples, we found that our measurement approach can verify the expected signal link budget within a error of 14 dB. In the concluding section, measurement results are summarized.