LTE reconnecting in 3-10 seconds

[joshuab1986]

Hello,

This may be normal behavior once correct connection management code is in place, but I want to verify since originally I was looking at 2-3 minute connection times on power cycles. Since combining the following steps upon a disconnect request in my code, the nRF9160DK I'm using will reconnect to LTE after wake-up or complete power cycle in a matter of seconds. I'm very much pleased with this, but I want to ensure it's correct behavior... I've went as far as leaving the board disconnected from power for days and it will still power up and connect very quickly.

lte_lc_offline();

lte_lc_power_off();

bsd_shutdown();

nrf_regulators_system_off(NRF_REGULATORS_NS);

After this process was implemented for disconnecting, I can power cycle or manually trigger a wake up and the module then does the following:

lte_lc_init_and_connect();

The init and connect completes in 3-10 seconds and I'm online passing data without issue.

I've tested 2 networks iBasis and Hologram to verify the same behavior, and indeed it results in the same. Obviously when changing the SIM card out the first connection takes a longer amount of time. I want to assume it's the subscriber information stored on the SIM after the initial connection, but I want to be certain that this is correct behavior?

[joshuab1986]

I might have answered my own question... Just remembered the modem flash. So probably the proper shutdown is storing information in the flash that is used later? I have delay and error checking in the steps I originally mentioned so everything should be shutting down happy.

[Hakon]

joshuab1986 said:

So probably the proper shutdown is storing information in the flash that is used later?

 Yes, when the modem is turned off, band information is stored in flash. If you want fast connection time you should consider using the %XBANDLOCK command.

[joshuab1986]

Hakon Thank you for the confirmation, and the band locking tip.