nRF9160 - Improve slow cellular registration

[Vincent44]

Hello,

I was wondering if there if there is way to improve the the network registration process on a custom board with nRF9160.

I currently have a typical "engineer setup" to work on the firmware (custom board equipped with an nRF9160 and a 1NCE SIM card, sitting on my desk).
It works great. However, when uploading a new firmware, the duration to re-connect to the network is very inconsistent : sometimes it connects within less than 30 sec, and sometimes it is still not connected after 3 minutes. In both cases, the device it at the same location, on my desk.

Because my device might be placed in a location where network is not reachable, I have implemented a timer that will switch off the device in case it takes too long to connect. This will prevent draining too much battery. The question is : how long is too long ? Is there a way to improve that ? For example, being able to detect that there are no cells around, so there is not point waiting for too long ?

Thanks.

Vincent

[Håkon Alseth]

Hi,

 

Is there a bad reception where you are testing?

Can you share the output of AT%XMONITOR ?

 

It works great. However, when uploading a new firmware, the duration to re-connect to the network is very inconsistent : sometimes it connects within less than 30 sec, and sometimes it is still not connected after 3 minutes. In both cases, the device it at the same location, on my desk.

When you say new firmware, do you mean new modem firmware or application based firmware? If it is new modem fw, it will clear information related to the cell towers that you've successfully connected to in the past.

Because my device might be placed in a location where network is not reachable, I have implemented a timer that will switch off the device in case it takes too long to connect. This will prevent draining too much battery. The question is : how long is too long ? Is there a way to improve that ? For example, being able to detect that there are no cells around, so there is not point waiting for too long ?

This highly depends on your application and what you deem to be "too long". I can state that the modem itself will duty cycle its searching over time, to avoid excessive current consumption.

You can have a look at this AT command: https://infocenter.nordicsemi.com/topic/ref_at_commands/REF/at_commands/mob_termination_ctrl_status/xdataprfl_set.html?cp=2_2_0_4_13_0

Which also sets how the periodic search behaves:

https://infocenter.nordicsemi.com/topic/ref_at_commands/REF/at_commands/nw_service/periodicsearchconf_set.html

 

Kind regards,

Håkon

[Achim Kraus]

Other tickets about the "periodicsearchconf" already turned out, that on missing networks the modem stay in idle (for emergency calls, even if it's unclear, how that applies to the nRF9160) instead of sleeping. And that the modems sticks to network rejection, which then requires either to wait longer or switching the modem off/on.