FOTA with NB-IoT failing

RE: FOTA with NB-IoT failing

zhaw-moss — Tue, 19 Oct 2021 11:08:01 GMT

Hi Charlie,

thanks for your reply and your help. It seems like it won't work in Switzerland with Swisscom. So I think this thread can be closed.

Best wishes,

Simon

RE: FOTA with NB-IoT failing

Charlie — Tue, 19 Oct 2021 10:42:52 GMT

Hi Simon,

The iBasis SIM card does not support our local NB-IoT network in Norway, so I did not have a chance to test it myself.

I check with my colleague who has done FOTA over NB-IoT, here is his impression:

I've tested FOTA over nb-iot with SLM.
It works, but it is slow and prone for retries. (so download stops, and resumes when the connection is stable again)
FOTA over nb-iot takes a long time and is power-hungry, but it should work. (however, recommended to use LTE-M if available)

Best regards,

Charlie

RE: FOTA with NB-IoT failing

zhaw-moss — Mon, 18 Oct 2021 15:42:07 GMT

Hi Charlie,

thanks! I tried it again, doesn't work, trace attached. Let's put it in another way: Do you or anyone else ever managed to properly do a FOTA over NB-IoT?

devzone.nordicsemi.com/.../trace_2D00_2021_2D00_10_2D00_18T15_2D00_35_2D00_53.786Z.pcapng

Best wishes,

Simon

RE: FOTA with NB-IoT failing

Charlie — Mon, 18 Oct 2021 12:51:47 GMT

Sorry, the latest NCS uses a different way to configure APN, I have corrected the former suggestion.

RE: FOTA with NB-IoT failing

zhaw-moss — Mon, 18 Oct 2021 12:13:18 GMT

Hi Charlie,

Thanks for yor answer.

If I add those two lines I get the error that these Kconfig symbols are undefined:

c:\Users\moss\Code\application_update_moss\prj.conf:68: warning: attempt to assign the value 'y' to the undefined symbol LTE_PDP_CMD

c:\Users\moss\Code\application_update_moss\prj.conf:69: warning: attempt to assign the value '"1\"IP\",\"globaldata.net\""' to the undefined symbol LTE_PDP_CONTEXT

Do I have to somehow activate those config options? I'm using the nRF Connect SDK 1.7.0.

Best regards,

Simon

RE: FOTA with NB-IoT failing

Charlie — Mon, 18 Oct 2021 11:37:40 GMT

Hi Simon,

I find some discussion mentioned that Swisccom does not enable the APN correction on its network that means the user needs to specify the correct APN in the device.I guess this might be the cause of the problem. Please try to add the following lines to the configuration file:

CONFIG_PDN_SYS_INIT=y
CONFIG_PDN=y
CONFIG_PDN_DEFAULTS_OVERRIDE=y
CONFIG_PDN_DEFAULT_APN="1\"IP\",\"globaldata.net\""

Regarding TCP over NB-IoT, while NB-IoT supports both TCP and UDP as transport protocols. However, TCP is sensitive to delays and packet losses during data transmission. If you compare the feature of LTE-M and NB-IoT, "TCP over NB-IoT" is not a good practice on TCP/MQTT, TCP/HTTP/FOTA solution, you should use LTE-M as your first option.

Best regards,

Charlie

RE: FOTA with NB-IoT failing

zhaw-moss — Thu, 14 Oct 2021 15:43:06 GMT

Hi Charlie

The PSM was set by default. I tried again after I disabled it (set the first three digits to one).

But it is still failing, maybe there are some timeout parameters set by the carrier, I cannot say that.

With your btw tipp of converting the bin to pcapng I looked into the trace myself. It still does the RCC Release, see attached.

What is visible too is that there are loads of TCP retransmissions, double ACK and out-of-order packets - It seems like the tcp communication just isn't working as intended.

I have heard about problems with NB-IoT and TCP. So I'm asking myself if its just not possible to properly communicate with TCP over NB-IoT (or only if you're lucky), what do you think?

devzone.nordicsemi.com/.../trace_2D00_2021_2D00_10_2D00_14T15_2D00_31_2D00_32.772Z.pcapng

Thanks and best wishes,

Simon

RE: FOTA with NB-IoT failing

Charlie — Thu, 14 Oct 2021 14:47:59 GMT

Hi Simon,

I convert your trace to pcapng and checked with wireshark. The last message is an LTE RCC Release command. Have you set the PSM or does your carrier have some keep link timeout parameters?

NB-IoT has low speed and it may take a very long time to finish a FOTA downloading, this might exceed some time limits.

Best regards,

Charlie

RE: FOTA with NB-IoT failing

zhaw-moss — Thu, 14 Oct 2021 11:41:15 GMT

Hi Charlie

Yes, I tested the NB-IoT connection before, but I doublechecked it with the AT Client sample and it works.

I recorded the trace of two attempts. In the first attempt it failed before the download started. In the second attempt it failed after it downloaded the first two fragments. Log below:

*** FIRST ATTEMPT ***

*** Booting Zephyr OS build v2.6.99-ncs1  ***
HTTP application update sample started
LTE Link Connecting ...
LTE Link Connected!
Press Button 1 to perform application firmware update
I: Configuring socket timeout (30 s)
I: Connecting to hidden-domain.com
I: Downloading: FOTA/app_update.bin [0]
E: Error in recv(), errno 116
E: Download client error
Received error from fota_download


*** SECOND ATTEMPT ***

*** Booting Zephyr OS build v2.6.99-ncs1  ***
HTTP application update sample started
LTE Link Connecting ...
LTE Link Connected!
Press Button 1 to perform application firmware update
I: Configuring socket timeout (30 s)
I: Connecting to hidden-domain.com
I: Downloading: FOTA/app_update.bin [0]
I: Downloaded 512/167219 bytes (0%)
I: Downloaded 1024/167219 bytes (0%)
E: Error in recv(), errno 116
E: Download client error
I: MCUBoot image upgrade aborted.
Received error from fota_download

devzone.nordicsemi.com/.../trace_2D00_2021_2D00_10_2D00_14T11_2D00_24_2D00_14.754Z.bin

Thanks and best regards,

Simon

RE: FOTA with NB-IoT failing

Charlie — Thu, 14 Oct 2021 08:21:15 GMT

Hi Simon,

Ok, have you tested the NB-IoT connection before? You can use nRF9160: Serial LTE modem or nRF9160: AT Client.

If you can confirm there is no issue with the NB-IoT connection, please record the modem trace and share it with us for further analysis.

Best regards,

Charlie

RE: FOTA with NB-IoT failing

zhaw-moss — Thu, 14 Oct 2021 06:25:51 GMT

Hi Charlie,

thanks for your answer.

No, I'm not using the default iBasis SIM card. We have Swisscom IoT simcards running with both LTE-M and NB-IoT enabled.

Best wishes,

Simon

RE: FOTA with NB-IoT failing

Charlie — Wed, 13 Oct 2021 14:06:24 GMT

Hi Simon,

Are you using the default iBasis SIM card? iBasis has no NB-IoT network coverage in Switzerland now. You may need to check with iBasis or local carrier to check the locol NB-IoT support.

Best regards,

Charlie