Cannot enter PSM sleep every 12hr

[Tim Chao]

Hi,

I follow the Power optimization for nrf9160 to implement the modem power saving.

And here is my test parameters

- NB-IoT

- Data publish interval = 10m

- PSM parameter, TAU = 5040, Active Time = 0 (by psm param updated)

- Modem power-off delay timer = 30s (after received RRC idle, for handling the case that modem cannot enter sleep)

- Data profile = Ultra-low power mode

When I doing a long time test at weekend, I found that the modem cannot enter sleep every 12 hours.

Does anyone has similar experience about this 12 hour behavior?

Log (in normal case)

[11:50:11.451,171] <dbg> modem: link_ind_handler: Wake up from PSM
[11:50:11.945,465] <dbg> modem: handle_modem_event: Modem Evt: Search done
[11:50:12.953,979] <dbg> modem: link_ind_handler: RRC mode: Connected
[11:50:13.397,979] <inf> app_event_manager: e:led_state_event DATA_PUBLISHED
[11:50:19.976,989] <dbg> modem: link_ind_handler: RRC mode: Idle
[11:50:20.087,493] <dbg> modem: handle_rrc_idle: Schedule modem off by PSM (0+30s)
[11:50:20.087,890] <dbg> modem: lte_lc_sleep_enter_handler: Sleep by PSM for 6479.00 seconds

Log at every 12:00, keep happen in 3 days

[12:00:11.451,324] <dbg> modem: link_ind_handler: Wake up from PSM
[12:00:12.113,708] <dbg> modem: handle_modem_event: Modem Evt: Search done
[12:00:12.850,250] <dbg> modem: link_ind_handler: RRC mode: Connected
[12:00:13.244,201] <inf> app_event_manager: e:led_state_event DATA_PUBLISHED
[12:00:19.941,162] <dbg> modem: link_ind_handler: RRC mode: Idle
[12:00:19.941,864] <dbg> modem: handle_rrc_idle: Schedule modem off by PSM (0+30s)
[12:00:49.941,955] <dbg> modem: modem_power_off: Power off modem (cfun 0)
[12:00:50.153,289] <dbg> modem: on_cfun: Modem is powered off
[12:00:50.153,381] <dbg> modem: pdn_event_handler: PDN 0 DEACTIVATED
[12:00:50.153,656] <dbg> modem: link_ind_handler: network registration status: Not registered
[12:00:50.153,747] <dbg> modem: link_ind_handler: LTE Cell changed: Cell ID: -1, Tracking area: -1
[12:00:50.153,778] <dbg> modem: link_ind_handler: LTE mode: None
[12:00:50.153,900] <dbg> modem: pdn_event_handler: PDN 0 NETWORK_DETACH

[Achim Kraus]

There may be many possibilities, one may  be a HPPLMN search. That means, the SIM card is configured to search for "Higher Priorized PLMN" in intervals. It may be the case, that you SIM uses a 12h interval and has some PLMN in your country in the priorized lists. A easy way to check that is to use a "locked PLMN" and not the "auto-select". And maybe you already used a locked PLMN which then shows, that it's not a HPPLMN search in your case.

[Tim Chao]

Thanks, I think you are right.

I run the test again last night, and this time, I saw cell changed and searching state report after that.

[12:00:17.060,150] <dbg> modem: handle_rrc_idle: Schedule modem off by PSM (0+30s)
[12:00:19.152,465] <dbg> modem: link_ind_handler: LTE Cell changed: Cell ID: 28662797, Tracking area: 12700
[12:00:19.152,526] <dbg> modem: link_ind_handler: LTE mode: LTE-M
[12:00:20.154,785] <dbg> modem: link_ind_handler: RRC mode: Connected
[12:00:20.282,897] <dbg> modem: pdn_event_handler: PDN 0 DEACTIVATED
[12:00:20.284,027] <dbg> modem: link_ind_handler: network registration status: Searching
[12:00:20.284,271] <inf> app_event_manager: e:net_state_event id=0x7b1b4 NET_STATE_DISCONNECTED
[12:00:21.535,644] <dbg> modem: link_ind_handler: RRC mode: Idle
[12:00:21.535,675] <dbg> modem: handle_rrc_idle: Reschedule modem off (30s)
[12:00:22.154,785] <dbg> modem: link_ind_handler: RRC mode: Connected
[12:00:24.727,691] <dbg> modem: link_ind_handler: RRC mode: Idle
[12:00:24.727,752] <dbg> modem: handle_rrc_idle: Reschedule modem off (30s)
[12:00:24.920,654] <dbg> modem: link_ind_handler: LTE Cell changed: Cell ID: -1, Tracking area: -1
[12:00:24.920,715] <dbg> modem: link_ind_handler: LTE mode: None
[12:00:54.727,844] <dbg> modem: modem_power_off: Power off modem

When I tried to use "locked PLMN" as your advice , the COPS command keep return error, I don't know why.

uart:~$ at at+cops=1,2,"46692"
+CME ERROR: 0

But at least, the modem is actually perform searching at that time as you said.

Thanks.

[Didrik Rokhaug]

Tim Chao said:

When I tried to use "locked PLMN" as your advice , the COPS command keep return error, I don't know why.

uart:~$ at at+cops=1,2,"46692"
+CME ERROR: 0

When using the "at" command in the Modem Shell, you must escape the quotation marks: at AT+COPS=1,2,\"46692\"

See the note and the examples in the documentation: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/cellular/modem_shell/README.html#at-commands

[Tim Chao]

Oh, my bad, thanks.