RRC mode / Are there debugging options to find out why RRC mode changed to connected

Is there a way to find you the reason for RRC Connect?

I'm using a simple software developed based on NCS AWS IoT sample. I've implemented the SW to test power consumption in different modem idle modes. The SW updates data to AWS periodically and is idle between update periods. For some reason the SW operates differently using different networks and I don't know why.

I had trouble with PSM earlier as I mentioned in this ticket: https://devzone.nordicsemi.com/f/nordic-q-a/80120/asset-tracker-v2-power-consumption-with-thingy-91

Now I know better and I know how to set appropriate PSM parameters that are accepted by network. The thing that I don't understand is why my device constantly transitions between RRC idle and RRC connected randomly when the device is in DNA network. The same RRC mode toggling is not present in Elisa or Telia networks, in those networks the idle modes work as expected.

In DNA network the device very seldom stays in RRC idle for 60 seconds which is the shortest possible active timer value granted by the network. As a result the modem usually won't go to PSM during the 20 minutes that is the keepalive time for AWS IoT MQTT.

If the modem goes to PSM in DNA network, it stays in PSM until the next periodic data update. Thus I'm guessing the RRC toggling is network (not AWS) originated, but I would like to know if there is something that I can do to prevent the toggling.

I've attached a log file with 2min data update interval. In the beginning of the log there are only application writes. After a reboot there are library debug logs with the following flags:

# debugging
CONFIG_LTE_LC_MODEM_SLEEP_NOTIFICATIONS=y
CONFIG_AWS_IOT_LOG_LEVEL_DBG=y
CONFIG_LTE_LINK_CONTROL_LOG_LEVEL_DBG=y
CONFIG_NET_LOG=y
CONFIG_MQTT_LOG_LEVEL_DBG=y
CONFIG_DATE_TIME_THREAD_STACK_SIZE=2048
CONFIG_DATE_TIME_LOG_LEVEL_DBG=y
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  • Hi IIKKA,

    Modem trace can help to analyze such kind of communication between device and cell station.

    Can you record modem traces with the DNA network and another normal network for your application?

    Best regards,

    Charlie

  • Hi Charlie,

    This is the first time I've used modem traces, I hope the attached files are ok. Attached is traces from two networks. The traces should have AWS connection at boot, then 4min idle and at 4min a data update.

    I am using Circuitdojo nRF9160 Feather HW in my measurements. Using Trace Collector V2 I wasn't able to trace using a board that is not Nordic DK. I took the traces using Trace Collector v1.1.2 and then tried to convert to Wireshark using Trace Collector V2. I couldn't verify the logs as "Convert RAW trace to PCAP" displays this error:

    11:39:15.459
    Failed conversion to pcap: end of file reached while searching db uid plugin path: C:\Users\ilkka\.nrfconnect-apps\node_modules\pc-nrfconnect-tracecollector-preview\node_modules\@nordicsemiconductor\nrf-monitor-lib-js\Release\win32-ia32\nrfml-insight-source.nrfmlTelia_modem_trace.bin
    If the logs are not good, I can try to trace again using nRF9160DK.
    Br,
    Ilkka
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  • Hi Charlie,

    This is the first time I've used modem traces, I hope the attached files are ok. Attached is traces from two networks. The traces should have AWS connection at boot, then 4min idle and at 4min a data update.

    I am using Circuitdojo nRF9160 Feather HW in my measurements. Using Trace Collector V2 I wasn't able to trace using a board that is not Nordic DK. I took the traces using Trace Collector v1.1.2 and then tried to convert to Wireshark using Trace Collector V2. I couldn't verify the logs as "Convert RAW trace to PCAP" displays this error:

    11:39:15.459
    Failed conversion to pcap: end of file reached while searching db uid plugin path: C:\Users\ilkka\.nrfconnect-apps\node_modules\pc-nrfconnect-tracecollector-preview\node_modules\@nordicsemiconductor\nrf-monitor-lib-js\Release\win32-ia32\nrfml-insight-source.nrfmlTelia_modem_trace.bin
    If the logs are not good, I can try to trace again using nRF9160DK.
    Br,
    Ilkka
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