Geolocalisation via LTE when not connected

[chouquette_fr]

Hi everyone,

I am trying to develop an application and I need to solve this situation : when the modem is not able to connect to LTE-M network, I still want to be able to retrieve cell-id information if available in order to track localisation of my device. So is it possible to get cell-id information when not connected via LTE-M ? Thanks

[Øyvind]

Hello, 

Have a look at the latest answer from Markus Tacker (he/him) here:
https://devzone.nordicsemi.com/f/nordic-q-a/73139/scanning-for-all-nearby-base-stations-with-nrf9160dk

Kind regards,
Øyvind

[Markus Tacker (he/him)]

I think this case is a little more challenging: from what I understand in this case the device has no internet connection at all, so while it is able to get cell information from the modem, it's not able to send this information to the cloud for processing there.

Nevertheless OP is interested in knowing the location of the device.

The information about the cell that the modem provides includes the MCC (mobile country code), and you can use at least this information "offline" / on the device to determine in which country the device currently resides.

I am not sure however, if this information (or AT+COPS?) is available if not connected to LTE at all.

[chouquette_fr]

I can use AT+COPS? to determine the MCC+MNC of the device even when not connected. However, I didn't succeed in getting information about cell id. 

[Markus Tacker (he/him)]

Yeah, that's what I suspected. However there are tens of thousands of cells per country, so knowing the cellId wouldn't help you much to further improve location information beyond the country if you have no connection at all.

[chouquette_fr]

I would like to record the different positions of the device and then send them to the internet once I am connected again.

[Markus Tacker (he/him)]

You could run AT%NBRGRSRP and store that data locally, then send it to the cloud once connected and have the cloud resolve the cell locations.