hello,
I am new to Loawan, I have designed a new hardware using RAK 11720 and now I am trying to figure out how I can use it in EU 868. I will not be able to stay with 1% duty cycle, I will need more messages ( at least in worst case if I end in SF12 for a while). As an alternative to 1% Duty Cycle ETSI has defined “5.21 Polite spectrum access”, that gives you 2,7% duty cycle if you do LBT+Frequency hopping so if you leave a busy frequency and try at an other.
Now I wonder how the RAK device handles these issues, in fact I ask myselve who controls the frequency / channel to use for the next transmission ?
I found an AT switch AT+LBT=1 but the RUI AT Spec does not tell much what that will mean:
In case of busy channel:
Will it just wait and try later ?
Willl it move to a different frequency and try there ? ( wanted solution) If so what algorithm will it use ?
My second Problem is to understand the " * [LoRaWAN Regional Commands] AT+MASK] * [AT+CHE] * [AT+CHS] * [AT+BAND]
They do not seem to be applicable in EU ?
At the end, where can I find information about the channel allocation of RAK 11720 at all ?
However “If no free channel is found, the packet is not sent.” means what exactly ?
After 1 round robin on all channels the packet is dropped ? What happens in case of an CMSG confirmed packet ? Does the Application host receive an error in that case ?, so the application level can still reinvoke retransmission if a confirmed message is important to the application.
If it can’t send, you will get an error response.
If you are using AT commands, it will be +EVT:TX_ERROR. If you are using a custom application, the error will be reported in the TX finished callback.
And, don’t forget, even if you enable LBT, IT WILL NOT WORK ON EU868
It is only available in AS923-1 in Japan and KR920
Please understand my stupid questions our knowledge is only based on theory we at charterware have not implemeted Lorawan before. Our 1. hardware sample containing STM32 CPU + RAK 11720 is just being manufactured.
By the way, it is mandatory in the EU if the device needs more than 1% duty cycle on a channel.
In a nutshell the rules say:
"Either use 1% duty cycle or polite spectrum access.
Whereas polite spectrum access is defined as LBT ( CAA ) along with frequency hopping if RSSI Signal > threshold. This allows for 2,7% duty cycle on just 1 channel. Given 8 one can archieve more than 20% device airtime.
So depending on your application needs it is mandatory.
thank you,
yes I saw that before. Lorawan Alliance spec currently restricts spectrum usage far more than ETSI which is probably for effort reasons (regionality).
At the end I only have to fulfill ETSI.
I just said “it is mandatory if you would like to use more than 1% duty cycle”.
Just please give it a chance and talk to your R&D. With strict 1% usage I am not sure we can implement our application.
