LTE reconnection issue

RE: LTE reconnection issue

Øyvind — Mon, 23 Sep 2024 08:41:25 GMT

Hi Eric,

Happy to hear that you found the answer to your issue. Let us know if you have any further issues with the network connection.

Kind regards,
Øyvind

RE: LTE reconnection issue

eguerard1 — Fri, 20 Sep 2024 14:37:33 GMT

Hi 0yvind,

I finally found the problem. By doing your modem traces, I tried another SIM card manufacturer and found that the first time the device register on the network, it connects in LTE-M. When the device lost connection, it tries to reconnect in NB-IOT. The problem is NB-IOT is not widely support in Canada. The supported bearers changed from SDK 2.5.2 and version 2.6.2. I had to enforce to use the LTE-M bearer by adding these configuration options in the prj.conf.

CONFIG_LTE_NETWORK_MODE_LTE_M=y

CONFIG_LTE_NETWORK_MODE_LTE_M_NBIOT=n

I just want to thank you for the quick support you gave me!

Best regards,

Eric

RE: LTE reconnection issue

eguerard1 — Fri, 20 Sep 2024 13:43:08 GMT

Hi 0yvind,

To my knowkedge, we don't use any special settings. We are using BELL sim card. It is activated for LTE-M. We also use the PDN library in the device.

Best regards,

Eric

RE: LTE reconnection issue

eguerard1 — Fri, 20 Sep 2024 13:38:56 GMT

Hi 0yvind,

I've just attached the modem trace files.

Many thanks for your support!

Eric

devzone.nordicsemi.com/.../trace_2D00_2024_2D00_09_2D00_20T12_2D00_23_2D00_55.324Z_5F00_SDK2.6.1_5F00_BELL.mtrace

devzone.nordicsemi.com/.../trace_2D00_2024_2D00_09_2D00_20T12_2D00_45_2D00_18.615Z_5F00_SDK2.5.2_5F00_BELL.mtrace

RE: LTE reconnection issue

Øyvind — Fri, 20 Sep 2024 09:25:01 GMT

From nRF9160_SDK2.6.1.pcapng I can see that your device is disconnected and receives two reject reasons

174 292.841370 AT 47 Rcvd AT Command: +CEREG: 2,"AD1D","0103EF81",9,0,9 188 293.481232 AT 48 Rcvd AT Command: +CEREG: 2,"AD1D","0103EF81",9,0,14

From 3GPP TS 24.301 Annex A we see that these are

Cause #9 – UE identity cannot be derived by the network.
This EMM cause is sent to the UE when the network cannot derive the UE's identity from the GUTI/S-TMSI/PTMSI
and RAI e.g. no matching identity/context in the network or failure to validate the UE's identity due to
integrity check failure of the received message.

Cause #14 – EPS services not allowed in this PLMN
This EMM cause is sent to the UE which requests service, or if the network initiates a detach request, in a PLMN
which does not offer roaming for EPS services to that UE.

Not sure what causes these, and with 2.6.1 only. Are you using the PDN library in your device? I.e. any special SIM settings ? I would reach out to your network provider for more information. As mentioned, the modem traces will provide us with more information on what causes this.

What SIM are you using? Is this activated for both LTE-m and NB-IoT?

Kind regards,
Øyvind

RE: LTE reconnection issue

Øyvind — Fri, 20 Sep 2024 08:38:48 GMT

Hi Eirc, no the modem trace (.mtrace) includes more information that is only readable by our team. You collect it using Cellular Monitor found in our nRF Connect for Desktop. The wireshark traces provide a lot of info as well.

Kind regards,
Øyvind

RE: LTE reconnection issue

eguerard1 — Thu, 19 Sep 2024 17:10:45 GMT

Hello,

Do you mean all AT command sent to the modem ? If yes, they are part of the pcap files.

Best regards,

Eric

RE: LTE reconnection issue

Øyvind — Thu, 19 Sep 2024 13:06:58 GMT

Hello,

Thank you for providing this information. Could you please provide modem trace? This provides more information on what is going on inside the modem. I will have a look at the wireshark traces as well.

Kind regards,
Øyvind