Question on overlay-ppp-cmux-linux.conf

[Mike Hsu]

Hi Sir,

I have a question about these two configurations in overlay-ppp-cmux-linux.conf, CONFIG_MODEM_BACKEND_UART_ASYNC_RECEIVE_IDLE_TIMEOUT_MS and CONFIG_MODEM_BACKEND_UART_SLM_TRANSMIT_TIMEOUT_MS

I saw the comments for these configurations in overlay-ppp-cmux-linux.conf were calculated by using 115200 buadrate
CONFIG_MODEM_BACKEND_UART_SLM_TRANSMIT_TIMEOUT_MS=521
CONFIG_MODEM_BACKEND_UART_SLM_RECEIVE_IDLE_TIMEOUT_MS=12

My question is, if we set the baudrate is higher than 115200, like 409600, does that mean above configurations need to be adjusted to
CONFIG_MODEM_BACKEND_UART_SLM_TRANSMIT_TIMEOUT_MS=130
CONFIG_MODEM_BACKEND_UART_ASYNC_RECEIVE_IDLE_TIMEOUT_MS=3

Or, I can remain keeping original settings?

Thanks.

[Benjamin]

Hi Mike,
I would think it would be reasonable to change them to match the new baud rate. I don't think it is practically needed but I guess it would be more efficient. It would be interesting to compare. Also, you'll need to change the baud rate to match your new in slm_start_ppp.sh and slm_stop_ppp.sh in the scripts directory.

Best regards,

Benjamin

[Mike Hsu]

Hi Benjamin,

Thanks for your reply. If would like to compare as you said, do you think how shall we do? It makes sense the baud rate in slm_start_ppp.sh in the scripts directory should be matched as well.

Best Regards,

Mike

[Benjamin]

You could run tests with benchmarking tools such as iperf3 to measure bandwidth and ping for latency and check for any noticeable variations.

Best regards,
Benjamin

[Mike Hsu]

Hi Benjamin,

Do you have suggestions how's to setup the local network environment through modem network to benchmark the performance by using iperf3? Is that meaning I need to setup 4G LTE router to create the local network environment?

Best Regards,

Mike

[Benjamin]

Since you are using overlay-ppp-cmux-linux.conf, I assume you are using the nRF9151 as a standalone modem with a Linux device? If so it should appear as a regular network interface (ppp0) and you can benchmark as normal.

Best regards,
Benjamin