LTE cell assignment

[fred7106]

Daer
usually we need minutes to lock the LTE cell and connect to the network. There is a way after the connection to save the data (NVM or flash)  and on restart to use them?

Federico

[jbrzozoski]

We originally noticed this on 1.0.0 and 1.0.1 a long time ago.  It is possible things have changed since then, but we still have our firmware query the setting using "AT+COPS?" at bootup and only send the "AT+COPS=0" command if that is our desired mode but not the response from "AT+COPS?".

[jbrzozoski]

A simple test we did to prove this behavior to ourselves, which you can use to see if it still happens:

1. Put the modem in auto-operator mode: AT+COPS=0
2. Put the modem online: AT+CFUN=1
3. Let the connect get online and stabilize
4. Put the modem offline: AT+CFUN=4
5. Put the modem back online and time it: AT+CFUN=1
6. Put the modem offline: AT+CFUN=4
7. Reset the auto-operator mode: AT+COPS=0
8. Put the modem back online and time it: AT+CFUN=1

In our experiments, the time for steps 5 and 8 from sending the CFUN command to getting online would be dramatically different.

[oapilo]

Thanks for your help. I downgraded modem FW to 1.0.1 but it didn't seem to have any effect, i.e. the times in steps 5 and 8 were almost the same (in the order of seconds). The full frequency scan with at+cops=? takes minutes. Maybe the behaviour of remembering the visited cells is more related to how the memory is handled with HW. I'm having Thingy:91 PCA20035 1.0.0 2019.33.

Well anyway, a documented AT command to clear the visited cells and EARFCN would be nice to have for testing implementations for mobile IoT applications. I noticed that some other cellular IoT module vendors have included that to their AT command set.

Best regards,

Olli