Gateway with GSM / high latency connection


#1

Hello,
I have this problem:
I have a gateway (rpi + rak831) connected to GSM with GPRS SIM800L card.
When I put a message on downlink queue i find this error:
“ERROR: Package rejected, date / time seems wrong, too early (current = 437628693, package = 437513124, …”
I was able to configure the GSM module only with the local timestamp and not in UTC timestamp (perhaps the cause of the error)
Has anyone managed to configure a gateway with the GSM module like sim800L?
Thanks


#2

That looks like a latency issue. E.g. the roundtrip between the uplink and scheduling of the downlink can’t be done within the (by default) required 1 second (data). The solution for this is to increase the rx_delay setting in loraserver.toml and re-activate your OTAA devices (OTAA uses 5 seconds delay and the join-accept contains the rx_delay value so that the device is directly aware about the longer delay). In case of ABP, you probably need to re-provision your devices with the rx_delay value and also update the device-profile in the web-interface.


#3

Unfortunately, even increasing the rx_delay value (5s and 15s) the problem is not solved.
Has anyone managed to create a Gateway with a GSM module capable of receiving downlink packages?


#4

Could you confirm that you have restarted LoRa App Server (to reload the loraserver.toml configuration) and re-activated your devices? LoRa Server keeps a state per device of the current active timestamp as long as you don’t re-activate your devices, it will keep using 1 second (and trying to send mac-commands to update the device).

You can validate that the new rx_delay is being used by subtracting the timestamp of the uplink from the downlink, if the difference is 1000000 (1sec), then the rx_delay then the device is still configured to use a delay of 1 second. You will find this information in the live LoRaWAN frame logs.


#5

sorry, in have restarted loraserver.
Now i try to restart lora app server with an rx_delay=5s


#6

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WORK!
Thank’s a lot!

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