XEPCO Configuration with NB-IoT and LTE-M enabled (MFW1.3.x)

[Umer Mahmood]

We are migrating from Modem firmware version 1.2.x to 1.3.x. Since it is now possible to enable LTE and NBIOT both using the following XSYSTEMMODE configuraton:

AT%XSYSTEMMODE=1,1,0,1

How does this affect other configuration?
Especially PCO configuration, should PCO be used or ePCO?

[Øyvind]

Hello, 

This depends on the network. If you are connecting over NB-IoT and your operator does not support extended Protocol Configuration Options (ePCO), select the option which enabled legacy Protocol Configuration Options (PCO) mode, i.e. AT%XEPCO=0

You can also set this in the application configuration (prj.conf) with CONFIG_PDN_LEGACY_PCO.

Kind regards,
Øyvind

[Umer Mahmood]

Hello! 
Thank you for your quick reply. I understand that some networks might not support ePCO, but can I assume all networks support atleast lagacy pco? 
What I am really trying to understand from the point of view of application development, is, do I need to implement a mechanisim to toggle between lagacy and ePCO every now and then using the relevant at command, whenever my device fails to connect to the network? 
Or should I simply use lagacy PCO and not worry about anything? Because from what I understand, for example just in Europe, I cannot be sure if all the networks my device will try to connect to, home network or when roaming, support ePCO or not. The goal is that the device should be able to make a connection successfully, not just in Europe but in USA/Canada and Asia as well. 

[Øyvind]

This is difficult to tell. It might be easier to use legacy PCO however I'm not certain what features are not included. 

The 3GPP standard (standard specification for mobile networks globally) specifies that NB-IoT networks support ePCO (extended protocol configuration options).

Many networks globally instead offer PCO. When a device attempts to connect expecting ePCO, it will not be able to get online. The two messages are different, so the device and the network don’t understand each other properly.

(https://www.digitalmatter.com/nb-iot-update-pco-support/)

You can find more information on ePCO from the technical specification 3GPP TS 29.274 version 13.9.0 Release 13.