OTAA transmission failure problem

LPWAN Modules / EVBs RAK3172
1

After building the LoRaWan system, we are testing RAK3172-EVB LoRa transmission.

Even if the gateway and device are close together,
As shown in the log below, sometimes transmission succeeds and sometimes it fails.

I am asking this question because I am curious about how to resolve this symptom.

LOG

[04:18:10]AT+VER=?
[04:18:10]AT+VER=RUI_4.0.6_RAK3172-E
OK
[04:18:13]AT+SEND=3:12345678
[04:18:13]OK
[04:18:16]AT+SEND=3:12345678
[04:18:16]AT_BUSY_ERROR
[04:18:18]+EVT:SEND_CONFIRMED_FAILED(4)
[04:18:19]AT+SEND=3:12345678
[04:18:19]OK
[04:18:25]+EVT:SEND_CONFIRMED_FAILED(4)
[04:18:26]AT+SEND=3:12345678
[04:18:26]OK
[04:18:30]+EVT:SEND_CONFIRMED_OK

2

In your log, I don’t see a JOIN confirmation. It looks like you are sending data without being connected to your LoRaWAN server.

Setup your RAK3172 correct to match with your gateway region (frequencies)
Setup your RAK3172 in your LoRaWAN server. Make sure DevEUI, AppEUI, AppKey are correct.

Send an AT+JOIN command to the RAK3172 and wait for it to connect to the LoRaWAN server.

Then try again after the device has joined the LNS.

1 Like
3

Join confirmed.
I restarted the device and transmitted, but the symptoms were the same.

LOG

[04:43:34]AT+JOIN=1:0:10:8
[04:43:35]OK
[04:43:40]+EVT:JOINED
[04:43:41]AT+SEND=3:12345678
[04:43:41]OK
[04:43:46]+EVT:SEND_CONFIRMED_FAILED(4)
[04:43:47]AT+SEND=3:12345678
[04:43:47]OK
[04:43:51]+EVT:SEND_CONFIRMED_FAILED(4)
[04:43:52]AT+SEND=3:12345678
[04:43:52]OK
[04:43:53]+EVT:SEND_CONFIRMED_OK
[04:43:59]AT+SEND=3:12345678
[04:43:59]OK
[04:44:00]+EVT:SEND_CONFIRMED_OK
[04:44:02]AT+SEND=3:12345678
[04:44:02]OK
[04:44:03]+EVT:SEND_CONFIRMED_OK
[04:44:05]AT+SEND=3:12345678
[04:44:05]OK
[04:44:09]+EVT:SEND_CONFIRMED_FAILED(4)
[04:44:10]AT+SEND=3:12345678
[04:44:10]OK
[04:44:11]+EVT:SEND_CONFIRMED_OK
[04:44:19]AT+SEND=3:12345678
[04:44:19]OK
[04:44:20]+EVT:SEND_CONFIRMED_OK
[04:44:21]AT+SEND=3:12345678
[04:44:21]OK
[04:44:25]+EVT:SEND_CONFIRMED_FAILED(4)

4

I missed that, sorry.

Confirmed messages are not a guarantee that the packet is really received by the LoRaWAN server. It just means that the RAk3172 is re-sending it if it doesn’t get an ACK from the server.

It still can fail due to

  • node is too far from the gateway, doesn’t receive the ACK’s
  • node is too close to the gateway, which can lead to over-saturation of the signal and the packets are nor received
  • network latency between the gateway and the LoRaWAN server
  • RX time windows are set slightly different in the RAK3172 and in the LoRaWAN server.

On the LoRaWAN server logs, can you see the packets arriving, are the same packages received multiple times?
On the gateway traffic logs, can you see the uplink data packets and the downlink ACK packets?

You can change the number of retries for confirmed packets with AT+RETY. Try to set the number or retries higher.

5

We found out that there was a problem with the channel and band of the network server, so we fixed it and now it is transmitting normally.
thank you.

I’m using a 16-channel gateway.
I wonder if it is okay to set this channel value.

channel value : enabled_uplink_channels=[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]

6

Channels 0 to 15 should be ok.

7

Thank you very much!!

8

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