We know that distance and power consumption are natural contradictions in communication systems. When the transmission power drops, the propagation distance must be very close. So how did LoRa solve this contradiction? The fundamental reason is that LoRa has a hyperlink budget, because LoRa can improve the sensitivity of the receiver and does not need high transmission power. The sensitivity of LoRa receiver is based on direct sequence spread spectrum technology. LoRa uses high spreading coefficient to obtain high signal gain. Usually, the signal-to-noise ratio of FSK needs 8dB, while that of LoRa only needs -20dB.
In addition, LoRa applies forward error correction coding technology to increase redundancy for transmission information and effectively resist multipath fading. The transmission efficiency is slightly sacrificed, but the reliability of transmission can be effectively improved. After all, LoRa doesn't need a high transmission rate.