LoRa is PHY of LoRaWAN, which is a Low Power, Wide Area (LPWA) networking protocol working at license free sub-GHz frequencies and targets Internet of Things (IoT) requirements. The LoRaWAN specification is developed and maintained by the LoRa Alliance: an open association of collaborating members.
There are two modulation schemes adopted in LoRa. One is GFSK and another is LoRa modulation. Chirped-FM based LoRa modulation was developed by Semtech Corporation and it is a Spread Spectrum technology with the increased receiver sensitivity by processing gain. The data rates of the system are mainly determined by Spreading factor and bandwidth, also related to code rate of channel coding. The typical bandwidths are 125 kHz, 250 kHz, 500 kHz.
LoRaWAN network architecture is deployed in a star-of-stars topology in which gateways relay messages between end-devices and a central network server. The LoRa frame includes Preamble for synchronization, Header (PHDR) to include system information, payload and CRC bits. The frame structures for uplink and downlink are shown below respectively.
LoRa Uplink PHY Structure
LoRa Downlink PHY Structure
So the key features of LoRa technology are low date rate, low cost, long battery life and long range communication.