FTP download speed for SARA-R410M

Hello everyone,

I ran some tests with FTP over LTE-M on the Sodaq SARA-R410M and the results are somewhat disappointing. The download speed was only 5.7kB/s. With the same simcard and a Quectel BG96 modem, I managed to get a download speed of 30.5kB/s.

Could someone help me explain this big difference?

Hi Niels,

According to the datasheets available, the R410M supports up to 300kbit/s DL which is a 20% lower than the 375kbit/s DL maximum of the BG96. This would suggest that the other factors might be affecting your results with the R410.

Could you provide some further information about your test setup? Are you using a specific library? What baudrate is in operation between the micro-controller and the R410?

Hi Gabriel,

To keep the tests as equal as possible, I used the same simcard and antenna for both modems. I used a terminal program to send the AT commands specified in the manuals of the modems. With both modems I downloaded a file from the speedtest.tele2.net FTP server to the internal storage, and measured the time this took. I repeated this test 3 times with both modems, getting similar results at every try.

I couldn’t find anything in my method that could explain the big difference, so I was hoping anyone on the forums could help me out.

Hi Niels,

Could you specify whether you are connecting directly to either or both modems, or are you routing your commands via an intermediate microcontroller?

Hi Gabriel,

I tried both ways with both modems, but since I save the data on the internal storage of the modem the results were similar.

I had a look at the datasheet for R410M last week, as far as I can see, the FTP commands do not support saving the data to a file on the modem. The data is downloaded and sent immediately across the UART, and so the overall download rate will be limited by the speed at which the modem can forward that data across the UART.

Hi @NielsVeul,

It seems the Network did not negotiate the MTU size either and the R410M kept the minimum size.
This is probably because of the MTU size default is set to the minimum value when no MNO Profile is selected with the firmware on the R410.

The Quectel modem uses by default the maximum MTU size.
This can explain why the Quectel is faster with default settings.

Can you redo your test on the R410 with settings the MTU size to maximum?

Best regards,
Jan

Hello @Jan,

How can I set the MTU size to the maximum? I can’t find an AT command in the manual that does this.

Best regards,
Niels.

Hi @NielsVeul,

I have send the question about how to set the MTU size to u-blox.

Best regards,
Jan

Hi @NielsVeul,

I got a reply from u-blox.
It’s indeed correct. You cannot set the MTU size.
In the next firmware version the default MTU size will be maximum.

Best regards,
Jan

Hi Jan,

Thank you for contacting Ublox. Is there an indication on when we can expect a firmware update that fixes this issue?

Best regards,
Niels.

Hi @NielsVeul,

They never say when we can expect the new firmware.
We get the new firmware usualy a few days after release.

Best regards,
Jan