Downlink class B either not send or not received

ChirpStack Network Server
1

I have a node configured to run class B. The gateway sends beacons, the node confirms received beacons and confirms switch to class B. A class B enabled device profile is used, the ping schedule 8 seconds matches the ping schedule of the node. Uplink data send from the node is received and correctly marked in the LIVE LORAWAN FRAMES of that device in the JSON with “classB”:true. When I send via MQTT data to the server, I can see it appearing in the LIVE LORAWAN FRAMES of the gateway, however “classB”:false and the downlink frame is never received by the node.

What is wrong, do I miss an important thing?

Some more information:
loraserver, lora-gateway version is 2.6.1

Since there was no reply on this topic so far, maybe because of missing information:

I use B-L072Z-LRWAN1 evaluation board from STM and the most recent Semtech LoRaWAN development branch, that fully supports my node. Everything seems to work, except, downstream data is not received while the ping slot configuration is ok.

Gateway protocol seems good:

May 24 15:46:50 rak-gateway ttn-gateway[29939]: ### [DOWNSTREAM] ###
May 24 15:46:50 rak-gateway ttn-gateway[29939]: # PULL_DATA sent: 3 (100.00% acknowledged)
May 24 15:46:50 rak-gateway ttn-gateway[29939]: # PULL_RESP(onse) datagrams received: 0 (0 bytes)
May 24 15:46:50 rak-gateway ttn-gateway[29939]: # RF packets sent to concentrator: 0 (0 bytes)
May 24 15:46:50 rak-gateway ttn-gateway[29939]: # TX errors: 0
May 24 15:46:50 rak-gateway ttn-gateway[29939]: # TX rejected (collision packet): 0.00% (req:37, rej:0)
May 24 15:46:50 rak-gateway ttn-gateway[29939]: # TX rejected (collision beacon): 5.41% (req:37, rej:2)
May 24 15:46:50 rak-gateway ttn-gateway[29939]: # TX rejected (too late): 0.00% (req:37, rej:0)
May 24 15:46:50 rak-gateway ttn-gateway[29939]: # TX rejected (too early): 0.00% (req:37, rej:0)
May 24 15:46:50 rak-gateway ttn-gateway[29939]: # BEACON queued: 529
May 24 15:46:50 rak-gateway ttn-gateway[29939]: # BEACON sent so far: 526
May 24 15:46:50 rak-gateway ttn-gateway[29939]: # BEACON rejected: 0

gateway beacon config is correct, I think:

               /* Beaconing parameters */
                "beacon_period": 128,
                "beacon_freq_hz": 869525000,
                "beacon_datarate": 9,
                "beacon_bw_hz": 125000,
                "beacon_power": 14,
                "beacon_infodesc": 0
2

Just found the problem by myself. The device profile class-B DR setting on the server was wrong. Downlink is received now. But it seams that I can’t go below 8 seconds ping rate. Currently 4 seconds is configured, but it still takes up to 8 seconds.

3

You can refer to the following link

5

Hi Thomas

Hope you are doing well ! . I am new to Lorawan world . I am using almost the same Hardware as you used . I am only able to send/uplink and receive/downlink the messages using loriot server . My target was to use the class B , but loriot server doesn’t have support for class B . So decided to switch to class B . I need your guidance how to do that on chirpstack (uplink and downlink the messages) via class B . Thanks in advance for the help and guidance .

Thanks
BR
Usman