RAK4600 retransmissions

Hello,

Does RAK4600 have a retransmission mechanism with confirmed messages?

I’ve recently bought a RAK4600 EVB and have been exploring its differents AT commands and RUIs examples, but can’t find anything related to retransmissions.

An important characteristic of retransmissions is that the frame counter is maintained every time in the retransmissions cycle. If this module version doesn’t have retransmissions is there a way to do it with RUI or with a host MCU?

I’ve not seen re-transmission in any RAK devices. In general, not many devices do re-transmission due to the reason you gave plus the confirmation of messages can be very use case specific so a generic mechanism (like the one built in to the LoRaWAN spec) can quickly be redundant.

You could extend the firmware with the RUI compiler to resend if you don’t get a confirmation back, but with a different frame counter and something in the payload that indicates a resend - the network may well have received the message but the device may not have heard the confirmation.

Overall, it’s much better to just send and if the application server spots a gap, send a message asking for a re-send of a single or range of data points - most devices have enough memory to hold a few days worth. This is made even easier to implement if you have your own counter and leave the LoRaWAN frame counter for its original purpose of preventing replay attacks.

More help is possible if we have a little more detail.

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Thank you for your answer Nick.
I noticed that the RAK4600 actually sends re-transmissions when a confirmed message isn’t acknowledged by the server, to be precise it re-transmits a maximum of 8 times with the same frame counter.

My guess is that RAK doesn’t expose this configuration through the RUI but somewhere in the SDK this must be set. Do you know if is possible to customize deeper than the RUI?

The RAK GitHub as repositories for both Arduino & MicroPython:


so in theory you can code your module just as you like. But not tried it personally.

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Great @nmcc, thank you!