I’m working on designing a sensor network+datalogger system for use in remote off-grid field sites in Alaska (or other places with no network or cell connection). TTN seems perfect for this in many ways except for the web-API aspect of it.
My question is: Is there a way to set up the TTN stack completely off-network? Ideally the whole system would run on a single small linux computer with a concentrator module which would act as the gateway and run the TTN stack in addition to an instance of InfluxDB or other database and a small web interface for downloading data from the system.
Is this reasonable? or is the TTN stack for more complex than it needs to be for less than 100 nodes in a system that doesn’t need encryption etc.?
Thanks for your thoughts.
The Multitech Conduit AEP gateways can do this as a fully self contained unit.
How will the gateways talk to the central site without a backaul network such as LTE, etc!
If the sensor nodes are within line of sight of the central site then you may not need LoRaWAN. In this case you could consider LoRa and using repeaters where you do not have line of site.
Do you know of any documentation of this being done?
In theory you could run all the pieces of the system on the same box, although they talk by network sockets having programs running on the same machine talk over the loopback interface is very standard.
That said it might be more than you need, but if you aren’t constrained by power supply to having an extremely lightweight computer, it may be that just doing that is simpler than creating exactly what you need.
Note you’ll have to put some real engineering into having a computer you can put out in the field and have run for months on end. Both to the hardware and the system software.
It is using LoRa peer-to-peer. If you are using something like the Microchip RN2903 or EU equivalent LoRa radio, then the peer-to-peer stuff is in their documentation for the radio. A repeater receives the LoRa packet and repeats it. You need to add some logic (set a bit in your own code) to indicate when a frame is being repeated. The the repeater code looks at the received frame, if your “repeated” bit set, if so discard the frame, if not, set the bit and transmit it.
There are other mechanisms you can use to support multiple repeater hops.
I would go for a plain LoRa system (not LoRaWan). I have a similar setup in Australia on an outback farm with unstable internet access. We have redundant receivers, one with a Raspberry Pi and one with a microcontroller and flash memory. I use only a single channel. The devices are underground and transmit in intervals with some randomization. The channel occupation is pretty low so that there are essentially no collisions of packets.