Measured scanning procedure a few minutes after connection establishment

Hello,

I'm doing a few power consumption tests on the nrf9160 DK with NB-IoT for a battery powered application. PSM mode works as expected but I measured a current drain of about 35mA a few minutes after the nrf9160 has connected to the cellular network (see screenshots below). The procedure that leads to the 35mA is as follows:

  1. Powered the nrf9160 DK
  2. Application on the nrf9160 establishes a connection to the NB-IoT network
  3. Application on the nrf9160 exchanges data with a cloud application every 60s (works as expected)
  4. About 2 minutes after the connection establishment procedure the nrf9160 modem consumes 35mA for about 1 to 2 minutes while the data exchange with the cloud still works as expected. 

In the case I linked below it turned out that the current drain of about 35mA is due to the network scanning procedure. I assume this also applies to my case. But in the linked case they only talk about a scanning procedure during the connection establishment process and not if the system is already connected.

https://devzone.nordicsemi.com/f/nordic-q-a/68411/9160-continuous-current-drain-during-cell-tower-connection----is-this-expected

Now I wanted to know if it is normal that the modem performs a scanning procedure while it is already connected?

If yes, can I disable the scanning procedure that is executed while in connection? Because it consumes a lot of energy and the nrf9160 is already connected anyway.

Start of the scanning procedure after a packet exchange

Packet exchange during the scanning procedure

How the scanning procedure looks like when zoomed in

End of the scanning procedure

I use the following setup:

  • nrf9160 DK revision 1.1.0
  • ncs v2.0.0
  • modem firmware is mfw_nrf9160_1.3.2
  • MNO is Deutsche Telekom

Thanks in advance.

Best regards,

Christian

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