Testing both NB-IoT and LTE-M

[Vincent44]

Hello,

I am trying to evaluate differences between NB-IoT and LTE-M in real world (power consumption, coverage, etc) using a nRF9160DK.

I started a simple project with the included iBasis SIM : works great on LTE-M in France, but NB-IoT is not supported.

I ordered a SIM supposed to be handling both NB-IoT and LTE-M, but I am running in some trouble.

This SIM card connects to NB-IoT, but does not connect using LTE-M ... eventhough it reaches some antennas. No matter if I set the NB-IoT or LTE-M as preferred network.

Here is what I get from my custom firmware.

Button 2 pressed - Waking up !

Reading probe (blocking) ...

> Temperature: 22.44

> RHumidity: 23.26

Resetting modem done

Setup cellular modem : Done

> Check events for connection status

[LTE LC event] Network registration - Searching

[LTE LC event] Cell Update - id:13827****, tac:3****

[LTE LC event] Modem mode has changed to LTE-M

[LTE LC event] RRC Connected

[LTE LC event] RCC Idle

[LTE LC event] Cell Update - id:13828****, tac:3****

[LTE LC event] RRC Connected

[LTE LC event] RCC Idle

[LTE LC event] RRC Connected

[LTE LC event] RCC Idle

[LTE LC event] RRC Connected

[LTE LC event] RCC Idle

[LTE LC event] RRC Connected

[LTE LC event] RCC Idle

[LTE LC event] Cell Update - id:1428****, tac:1****

[LTE LC event] RRC Connected

[LTE LC event] RCC Idle

[LTE LC event] Cell Update - id:15787****, tac:4****

[LTE LC event] RRC Connected

[LTE LC event] RCC Idle

[LTE LC event] Cell Update - id:-1, tac:-1

[LTE LC event] Modem mode has changed to none/off

[LTE LC event] Cell Update - id:13827****, tac:2****

[LTE LC event] Modem mode has changed to NB-IoT

[LTE LC event] RRC Connected

[LTE LC event] Network registration - Connected, Home network

[LTE LC event] PSM Update - TAU: 3960, Active time: 60

SIM ICCID : 89332011************

Modem info :

> MMC + MNC (3+2 digits): 20820

> APN: ido.net

> LAC: 0x5*** = 2****

> Cell ID: 0x083D**** = 13827****

* * * Server resolve skipped for debug * * *

* * * Send data to server skipped for debug * * *

Current PSM timings (TAU=3960 - AT=60) don't match desired values (TAU=900 - AT=16)

Requesting PSM timing.

> Request TAU: 900 sec (Rounded to: 900)

> Request AT: 16 sec (Rounded to: 16)

[LTE LC event] PSM Update - TAU: 2520, Active time: 32

Depending on the SIM card I use, with the same firmware, my DK can connect to either NB-IoT or LTE-M, which makes me believe that:

- There is no hardware problem.

- There is no configuration problem in the firmware.

- Both LTE-M and NB-IoT are covered in my area.

The service provider is telling me that the SIM card should be working with both network, and suggests an issue with my hardware/firmware.

Is there a sample project that I can test, implementing switching between NB-IoT and LTE-M ?

Is there something else I need to check and/or add to my project ?

Thanks.

[Didrik Rokhaug]

Hello again, and sorry for this taking a while, but Easter came in the way.

Do you know what Bouygues' M1 (LTE-M) subscription assumes (or could you ask them)? For example, what FGI bits must be set (in the UECapabilityInformation)? Do they expect the UE has IMS capability?

Best regards,

Didrik

[Didrik Rokhaug]

Hello,

Did you manage to solve your problems?

Did you ask Bouygues what they require of LTE-M devices?

Best regards,

Didrik

[Vincent44]

Hello,

I asked but did not get any response. It seems that the issue is due to the bad coverage in my area. At least, that's what has been suggested by Bouygues.

I have to say that I don't fully understand, since the iBasis SIM works perfectly fine in LTE-M. But it might be due to some agreements between service providers.
Anyway, I don't have much time to spend on this particular issue right now, so I will close this ticket. Thanks.