nRF9160 %XCOUNTRYDATA command

[Scott Jacobsen]

Can you please explain how the %XCOUNTRYDATA command can speed up network selection in a new location? Does the modem perform a general scan on all bands to determine the MCC of the first signal detected and then limit the search to the values in %XCOUNTRYDATA as it continues?  What happens when the modem power cycles?  Upon power up, does the modem always revert to the last known network, and if not found, then jump all the way back to the beginning and starts a general scan?  

[Scott Jacobsen]

I don't think I quite understand.   If we set XCOUNTRYDATA for numerous countries, say the maximum number of 70, what happens when the device changes countries?   How does it learn of the MCC so that it can decide what country to prioritize? Will XCOUNTRYDATA be effective in minimizing search when we perform a live over-the-air test on the module at a manufacturing facility in one country and then ship the product to another country?

[JONATHAN LL]

Initially device always selects a network (MNO) instead of a band. Device may then switch to another band via idle mode mobility (cell reselections) based on network configuration, or when loosing coverage without any candidates (known neighbor cells) for cell reselection.

During initial network selection device selects the network from what ever band the highest priority network is first found. Although there are scenarios where network can be selected only after all bands are scanned. In that case the strongest cell of a selected network is attempted first.

All above only have impact where the first contact to network is done, after that idle mode mobility and related network configuration takes over control on which band the device spends time in idle mode. In LTE-M it is also possible that network moves device to a cell on another band via inter-frequency handover procedure during LTE connection (this is one of the 3GPP Rel-14 features that are possible with nRF9160).

The way to impact the band priority is to use the XCOUNTRYDATA command. 

Regards,
Jonathan