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  • Case ID: 305331
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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.

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.

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  • 0 in reply to Vincent44
    Vincent44 said:
    Is trace supposed to be readable by non-Nordic people ?

    If you use the Trace Collector v2, you can convert the trace to a Wireshark .pcap. This will let you see the communication between the device and the network and server. It can even do this live, so you can see the communication happening in real-time.

    However, there is more information that what Wireshark will show in the .bin files. That information is not readable for non-Nordic people though.

    Vincent44 said:
    I hope I made this properly

    The trace seems a bit short, and I couldn't see any connection attempts from the modem. However, I do see some communication with a network, so there seems to be some information missing.

    However, I can confirm that it did find a cell from Bouygues Telecom.

    Could you try to take a new trace?

    If you are using a DK, you can use this .hex file, which I have configured correctly: 72343.merged.hex

    It is the at_client, so you will have to send the AT commands manually.

    If you do use it, I am particularly interested in the output from these commands (they enable notifications from the modem, and will not give information directly):

    It would be nice if you could run those commands before you start the modem with AT+CFUN=1

  • 0 in reply to Didrik Rokhaug

    Thanks Didrik.

    Attached the test requested.

    I also re-run a trace on my custom app, it might give some addition info ?

    trace - AT Commands.bin

    Fullscreen AT-log.txt Download
    trace - My App.bin

  • 0 in reply to Vincent44

    Does your application use UART1 (or SPI1 or TWI/I2C1)?

    The trace from the at_client is fine, but the trace from your application seems to be missing parts, similar to your first trace.

    You didn't set the system mode in the at_client trace (though that might have been bad instructions from me), but it starts by trying to connect to some LTE-M networks, before ending up connecting to an NB-IoT network in the end.

    The first connection attempt (LTE-M) is to Bouygues Telecom. The connection attempt goes as expected until the network asks for the devices capabilities. After the device responds, the network stops communicating (it closes the RRC connection). However, it does not give a reject cause.

    The device then tries to connect again a few times, both to the same cell, and to a different one (still Bouygues Telecom), but the same thing happens.

    After a total of 6 connection attempts, it gives up, and tries to search for other networks. In the end, it tries to connect to Altice, but is rejected with "PLMN not allowed".

    Next, it tries Orange, but is rejected with "EPS services not allowed in this PLMN".

    Both of these rejects can probably be explained by missing roaming agreements between the operators.

    It then switches over to NB-IoT, where it finds a cell from Bouygues Telecom, and this time it is able to connect.

    I will have to ask the modem team why the network releases the device after it sends its capability information. However, due to Easter, it might take longer than normal to get a response.

    In case you are interested, here is the communication between the device and the different networks: trace - AT Commands.pcapng

  • 0 in reply to 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

  • 0 in reply to Didrik Rokhaug

    Hello,

    Did you manage to solve your problems?

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

    Best regards,

    Didrik

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