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by anonymous
Hello,

I am trying to use a TRM250 as a test device to develop an NB-IoT over-the-air test method. To do this, I need to connect the TRM250 to the network created by a communication tester (R&S CMW500). Even with a cable to connect the TRM250 to the communication tester I am not able to get a connection on GSM, LTE Cat M1, or NB-IoT.

Is there some test mode that the TRM250 needs to be put into to allow connections from any service provider? I am using a test SIM card that is registered with the communication tester. Is there a sequence of commands to initiate a connection?

Thanks, any help would be appreciated.

1 Answer

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by anonymous
Hello,

May I ask whether the device works with a regular SIM card?

Regards,

Justin
by anonymous
Hi Justin,

The device is able to connect to an operator network using LTE Cat M1 when using a regular SIM card. NB-IoT could not connect, but the operator may not support NB-IoT.

I will contact R&S, the manufacturer of the communication tester to see if they have any tips for setting up an NB-IoT connection as well.

Regards,

Sara
by anonymous
Sara,

TRM250 should not require complicated configuration to make it work. Also, I won't be able to tell how exactly you could connect it to your device, because this is not a regular computer.

Please let me know what R&S suggests you, if that is going to be from a device side, I will try my best to help you.

Regards,
Justin
by anonymous
Hi Justin,

I've been able to get a connection with a different SIM card and after setting AT+QCFG="iotopmode",1. I also had to change the band to Band 1 and the channel bandwidth to 10 MHz on the CMW500. I think I likely had a test SIM card that did not support NB-IoT.

Does the TRM250 support UE reporting of RSRP values? I can see there are AT commands to read the RSRP value, but can it report the value over the air?

Thanks,

Sara
by anonymous
Sara,

No, it can't do that.

Regards,
Justin