Zephyr LoRaWAN Cannot use DR0 and DR1 on AS923 and AU915-928

[jumper385]

Hi All,

I am currently doing range tests for a project and I stumbled upon an issue with the LoRaMAC library. Despite trying to disable adaptive data rates using lorawan_enable_adr(false) and manually setting the data rate to DR0 with lorawan_set_datarate(LORAWAN_DR_0), the library persistently auto-sets the data rates to between DR2 and DR6.

Upon digging deeper, I realized that the root of the issue lies in the region-specific override files provided by Semtech in the Zephyr LoRaMAC library. Specifically, the definition for AS923_DWELL_LIMIT_DATARATE as DR_2 in RegionAS923.h seems to be the culprit.

#define AS923_DWELL_LIMIT_DATARATE                  DR_2

My debugger's step-through pointed me to the RegionAS923GetPhyParam function where the data rate is being set to DR2 (SF10BW125). However, when I tweaked the definition to DR_0, the received packet data rate displayed as DR0 (SF12BW125), just as intended.

Interestingly, RegionAS923.h has the correct definition for the minimum data rate as DR_0:

#define AS923_TX_MIN_DATARATE                       DR_0

Is there a way to disable the dwell limit data rate, and configure the RegionAS923GetPhyParam function to adopt AS923_TX_MIN_DATARATE instead, either via the project's config file prj.conf or directly within the project’s source files? Could there be a limitation with Zephyr causing this? Additionally, I know that there are regulatory requirements that LoRaWAN needs to comply with - specifically the 400ms dwell time limitation HOWEVER, I'm not aware of that regulation in Australia. I beleive this is the origin of the setting but i'm not sure what standard/regulatory reference it's complying with...

Kind Regards,
Henry

[JordanYates]

Based upon the conversation in this link (https://www.thethingsnetwork.org/forum/t/as923-dwell-time-limitation-for-australia/36601/8) even if the legal requirement for the 400ms dwell time was dropped, it can still be part of the Lorawan spec.