Gateway Mesh / Rx delay configuration

Question

Hi,

We are experiencing an issue with downlink ACK reception on LoRaWAN devices using Mesh gateways with ChirpStack.

Current configuration :

RX Delay set to 12s in the Device Profile
Network: ChirpStack + Mesh gateways
Uplinks are correctly received
Downlink acknowledgements are never received by devices

Issue:

Even with RX Delay configured to 12 seconds in the Device Profile, devices never receive any ACK downlinks.

Questions:

Are there other ChirpStack parameters (Network Server, Application Server, Gateway Bridge, etc.) that affect RX1/RX2 delay timing?
Are there any specific settings on the Mesh gateways (buffering, latency, scheduling, time sync, mesh routing, etc.) required for LoRaWAN downlinks?
Are there known constraints between:
- High RX Delay values (12s)
- Downlinks
- Mesh gateways
- ChirpStack

Possible causes we are investigating:

Mesh latency incompatible with RX windows
Time synchronization issues (NTP / GPS / PPS)
Downlink generated by ChirpStack but never transmitted by the gateway
Mesh network downlink scheduling problems

If anyone has already faced this setup (Mesh gateways + ChirpStack), any feedback or experience would be highly appreciated.
Thanks in advance for your help

Julie · Answer

Hi,

Thanks for your help.

We checked and the mac-command is well sent by Chirpstack but the device never received it because the original RX2 timeout is too short.

If the default RX2 timeout on the device side is for example 2 seconds, the delay expired before the DL packet arrive at the device (because of radio between each gateway). The only way we succeed to reconfigure the RX2 timeout by mac-command is to deactivate the "ignore direct uplink" on the border gateway, launch the device and next run it with relay gateway.

This is OK for test purpose but we can't do that on real life.

Regards

Gateway Mesh / Rx delay configuration

1 Answers