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LoRa is the technique to send messages on the free wireless ISM network bands. The method is based on Chirps, which is an old radar technique. Sending data goes super-slow. Think about Morse coding, LoRa is slower... But by using this technique, with low power, a message can be send that survives a lot of noise, meaning it can be picked up by a gateway on a much further distance.

These gateways can be deployed by everybody, and can be private (costs might be involved) or public (free!). The Things Network did build a backbone for the gateways, and a transport protocol with front-end website to monitor your gateway and device. That is where the term LoRaWAN comes in; it is the full stack end-to-end to send and receive a message.

To make use of projects based on LoRaWAN, you need to be within reach of a gateway. Otherwise it will send your messages, but they will never get received. On the EMF campground, it looks like there is no coverage. That is why we bring a LoRaWAN gateway based on a Raspberry Pi + RAK 2245 + good antenna, plugged in to the EMF Camp network. This should give a coverage of about 10km (~6 miles), plenty of range for the full campsite!

With LoRaWAN the tricks are in the little details:

  • Hardware: let your device sleep most of the time (temperature every 60 seconds? Or is once an hour enough?), so your device can run on a coin cell battery for a looooong time
  • Payload: the smaller your message (temperature in 4 digit precision? Or is once an hour with 1 digit enough?), you need less radio time, less sending power, so you get longer battery life!
  • In short, acquire only useful data: Your sensor can track temperature, humidity, air quality, acceleration, gps and send that up to the network every minute. But you actually only need the GPS location, when the sensor moves. Again, it is all about the balancing game for longest battery life!

If there is interest on this topic (also Helium, NBIoT, etc), we can organize some meetup!

Long-range low power networks
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