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NRF9160 Registration times

Thomas

Hi,

In the cops=0 state, how long does the modem take to scan each band of both cat-m1 and NB-IoT? How does a roaming sim affect these times for both technologies? In other words, how long should we be waiting to connect with all bands enabled before deciding there isn't a network available in the area, and powering down to save energy?

  • 0

    Hi Thomas,
    This is very difficult to give a specific answer to since there are too many variables that depend on this.

    e.g.

    • It depends on the access technology since NB-IoT is slower and additionally in "MTC RSSI scan" is supported for finding rough estimate where to search first.
    • It also depends on the number of supported bands and from which band desired network is found.
    • It depends on the User Equipment (UE) (nRF9160 in this case) has some historical knowledge about the radio landscape which it can use to prioritize searched channels.

    So as you see it depends on several things which make it almost impossible to say how long it would take.

    Please note that if the nRF9160 does not find the network it will go to sleep automatically to save power. 

    i.e. Power consumption decreases significantly after all bands are searched, and therefore it is not fatal for the application to keep the modem ON a bit longer to make sure that all possible bands are searched.

    Best Regards,
    Martin L.

  • 0 in reply to Martin Lesund

    Hi Martin,

    I inserted a local sim from a network that isn't available in this area yet to have it scan and monitored the power draw. It searched bands 1, 2, 3, 4, 5, 8, 12, 13, 17, 20, 25, 26, 28 and 66, with band 28 and 8 having active networks. It entered this low power state for 30 seconds, but it then restarted the whole process, is there a way to make it do a "one shot scan"? Or a way to check if it is done?

    With that in mind, do you have a worst case time with all bands enabled? 

    Kind regards,

    Thomas

  • 0

    Unfortunately, I do not have any numbers for the time this can take.

    You can greatly reduce the time for the band search by locking the modem to only search on specific bands using AT%XBANDLOCK.

    You can test this out by running the at_client sample with the LTE Link Monitor.

    How did you do your test? 

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