LoRa is not LoRaWAN

Two names

LoRa is how the radio signal is made: the chirps, the spreading factors and the packet of the earlier lessons. LoRaWAN is a specification from the LoRa Alliance for the network on top of that radio. A product can use LoRa without being LoRaWAN.

What a gateway is

A LoRaWAN gateway is built around a concentrator, a chip that listens to several channels at once, typically eight, and to every spreading factor. When it hears a packet it forwards it to the network server with the level it was heard at, its signal to noise ratio and the time. It does not interpret the soil reading. That is the job of the server and the application behind it.

One uplink, two gateways

The probe does not address a gateway. It sends into the air, and any gateway that hears it forwards it. When two gateways hear the same uplink, the network server keeps one copy and notes which gateways heard it. A second gateway therefore adds a second chance of hearing a packet, with the node doing nothing different. The bench draws the forwarding as boxes, because the map does not say what reaches what.

Raw LoRa

Between two radios with the same settings you have raw LoRa: no addresses, no server, no network and no encryption of its own. A packet sent by one is a packet of bytes at the other, and what they mean is up to your code. That is enough for plenty of projects.

A single-channel receiver

A microcontroller with one radio chip can be made to hear one channel at one setting. It is a useful experiment. It is not a LoRaWAN gateway, which has to hear several channels and every setting at once.

The next lesson covers the rhythm of messages and the keys. If you pass a reading on to an application afterwards, MQTT is a common next hop.

Common mistakes

• Calling any LoRa radio a LoRaWAN device. LoRaWAN is a set of network rules, and a node must follow them to join a network.
• Building one radio on one channel and calling it a gateway. It hears a small part of what a gateway hears, and cannot serve a LoRaWAN network.
• Assuming a node chooses its gateway. It sends into the air, and every gateway that hears it forwards the packet.