Setting up new Gateways

Hi I am setting up two gateways (one 868mhz and one 433mhz), both Rpi based. I am considering whether to set up my own private chirpstack server, or put my devices and gateways on TTN so as others can in theory benefit from my gateways. I have a few questions though:

  1. Does TTN support both frequencies or only the 868mhz?
  2. Does TTN support moving gateways? One of mine will be moving regularly but will have GPS on.
  3. Will using TTN significantly effect the latency I see on packets for my own devices? Compared to a chirpstack server on my local network.
  4. I am assuming that if my GW is on TTN I will be subject to a limit on nodes like everyone else on the TTN network. But can I run some nodes locally unregistered for unlimited personal devices only on my own gateway? I’ve only used peer-peer LORA before, this might be obvious when i get started…

Depends on your region - check the frequency plans page in the docs - and consider that in some regions it may be supported but you may be the only one using it.

No public LoRaWAN network supports moving gateways and we particularly ask that they are not connected to TTN - the GPS is irrelevant, it only tells you where it is, which you know because you put it there - and what the time is - which is irrelevant as it is connected to the internet. If you setup a gateway and other peoples devices are heard by it, the LNS may well adjust settings based on the gateway, which when it disappears, will leave the devices out of range until they do a connectivity check.

To be clear, a gateway that’s moving that is on TTN is a form of denial of service to the community. So please don’t.

Depends. If your CS server is on your home network, no, but then that’s a bit obvious. If you host externally, it is deeply unlikely you will be able to replicate the finely tuned set of services and the raw horsepower that TTI provide.

However the latency of an uplink is not a thing - arriving inside 5ms or inside 25ms is totally academic for LoRaWAN which is not about command & control response times. I hit the test button on a device on my desk and my web browser shows me the information faster than I can move my eyes …

Yes, the FUP is as much about the use of the backend servers as not destroying the local airwaves with overly enthusiastic devices. But if you have a gateway and you have a device that needs more than 30 seconds air time a day, it’s likely to be a questionable use for LoRaWAN, even if the private legal limits would allow you far more uplinks.

Not if the gateway is on TTN.

A device has to be registered on an LNS and you need a gateway to relay the radio waves to the LNS, so you will need a gateway for your local nodes for the ‘unlimited personal devices’ which are an element you may need to explain - a node is a device is a MCU+radio+ sensors. And unlimited varies for corporate deployments in the hundred of thousands to five for your local techno-granny monitoring cat bowl weights.

Whilst you are deploying the unlimited low latency personal devices, you may want to factor in the local legal regulations.

Overall, get stuck in, but get one gateway and two or three devices setup so you’ve more context to your LoRaWAN adventures.

Many users like to concentrate on the devices & the dashboard / reporting and leave the LNS challenges to someone else. So please bear in mind that this forum is funded by TTI, so Chirpstack help isn’t available here.

Thanks Descartes, that is very useful.
The second Gateway if used would have to be mobile for my use case, so that will have to use a private LNS only.

“Yes, the FUP is as much about the use of the backend servers as not destroying the local airwaves with overly enthusiastic devices.”
I think we were talking cross purposes. None of my devices are or would be transmitting with a high duty cycle, easily less than 30s/24hr. That isn’t what Lora or LoraWan is for; I currently use peer-peer lora for a sensor, but I think using a LoraWan server will be more convenient for more sensors. I am more concerned with the number of nodes I can register and the limit on downlink messages. Although now that I have re-read your FUP I’m not sure why I thought TTN heavily restricted the number of nodes you could register, I had 8 in my head for some reason. The downlink message limit I might need to think about though.

Not mine, OURS - this is the TTN community which you are part of - it is designed to keep the network going. If you manage to spike the graphs on the dashboard, TTI will intervene decisively.

TTN personal use or testing/evaluation is typically 20-30 max, a registered community group on TTN is as many as a community needs as long as it is community use. If you are going wild with the number of devices that uplink once every six hours that’s different from 50 devices pushing it right up to the 30s. Otherwise there are paid for instances that will also give you access to TTN as well.

Not really much to think about, that’s more a spreadsheet situation - but if you have to think about it, it’s probably not for LoRaWAN. To put that in hard context, a downlink per fortnight is about right to do a link check with perhaps a setting to adjust. Maybe the occasional setting change. If you are thinking in terms of needing 10 per day per device and you have ‘unlimited’ devices, you will break your local LoRaWAN as gateways are deaf whilst transmitting - so 50 devices x 10 downlinks = 500 times the gateway can’t hear the other 49 devices. As above, LoRaWAN is not about command & control, that’s what I use P2P for.

Maybe you could say how many devices you are thinking of and what they are used for, will make it so much easier to give some guidance.

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This implies that you are going to be altering the algorithm as an almost full time job to feed in to your expected ‘message per multiple hours’ - the remote watering algorithms I’ve seen need a couple of weeks to settle the data and if it rains, you have to start all over again. So your downlinks are likely to end up few & far between.

But your call, always good to have another gateway on the network, but you do get ultimate freedom by staying on a local network.

Thanks, and yes I think you’ll be right about the downlink frequency when I get a little faith in it and won’t be tempted to manually “turn off and on”. Maybe once my equipment is in a more permenant state and I know what I need it to do exactly I’ll revisit the idea of my gateway joining TTN.

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