Send Without Join

Hi, I’m running several RAK4270 modules in parallel to create a test setup for a LoraWAN GW. One of the things I am testing is how well the GW handles simultaneous packets arriving on different channels. To that end, I have a small Python script that initializes the modules and then sends (somewhat) random data to different channels simultaneously. Currently I have the 4270s connected to TTN so I can see the data coming in as it is sent. Going forward, I would like the ability to send data without being joined to a network as I may not always have access to one. This is a GW under dev and I can monitor/validate the incoming data right at the hardware (I think). Is there a way to send data when the device isn’t joined? When I try just a normal send, I get an error response - which is expected. Just wondering if there is another way I’m not thinking of.

Hi @rbelk , if you are testing if you can cover many devices at once, then I think you are doing your test correct setting up multiple RAK4270 device. However, there is no workaround on the gateway side if two or more devices send at the very exact time at the same frequency, datarate and encoding. There can possibly be a racing condition on that one since the gateway receiver on one freq channel can only process one signal at a time.

Agreed. The plan is to set up the multiple 4270s to send on different channels so theoretically if I had eight of them, i could send data on all eight channels of a sub-band simultaneously and see how the GW handled it. The bigger question in my mind is if I need to be joined to a network for the devices to send data. I can do that if I need to but just trying to remove as many variables as possible during testing.

Hi @rbelk , yes the devices must be joined first before you can send data. LoRaWAN has symmetric encryption and the keys can be only obtained via joining process if you are OTAA. In ABP, the keys are hardcoded on both side, device and the network server.

I am not sure why you want to do that test. But that’s a good exercise to see the limitations of LoRaWAN. You’l see that there will be packet loss and those can be accounted to various factors. If your application is life threatening or very critical, LoRaWAN might not be the best fit for that. Although you can use confirmed message as a workaround but doing confirmed LoRaWAN packets is not good for the congestion on the gateways.