nRF9160 and eDRX mode on LTE-M connection

RE: nRF9160 and eDRX mode on LTE-M connection

Achim Kraus — Fri, 23 Aug 2024 05:43:59 GMT

I found the missing trick:

LTE_LC_MODEM_SLEEP_NOTIFICATIONS_THRESHOLD_MS is set to 20 minutes per default.

If a notification is wanted for eDRX 61.44s, it's required to adjust that value as well.

RE: nRF9160 and eDRX mode on LTE-M connection

Achim Kraus — Thu, 22 Aug 2024 17:06:44 GMT

I also tried to test, if "%XMODEMSLEEP:" reports something related to eDRX as the docu mentions with

"2 RF inactivity. Modem sleeps due to RF inactivity, including eDRX.".

I used a nRF9160-DK (mfw 1.3.6) and a nRF9161-DK (mfw 2.0.0).

I've tested with 655.36s and 61.44s.

I get the events, that eDRX is active in the cell, my PPK II shows the longer intervals. With that eDRX is active.

But "%XMODEMSLEEP: 2" is not reported.

Maybe, someone from Nordic helps with the details about the preconditions here. Not that in the end it takes a SIM card, which switches off for eDRx.

(If I enable PSM, "%XMODEMSLEEP: 1" gets reported, e.g. eDRX 61.44s, PSM act time 120s => "%XMODEMSLEEP: 1".)

RE: nRF9160 and eDRX mode on LTE-M connection

Achim Kraus — Thu, 22 Aug 2024 13:58:28 GMT

My inquiry sum-up:

The eDRX values are split into "requested", "provided by network", and "provided by cell".

The first two do have read functions and XMONITOR will also report the network value.

The cell values are only reported with change events/notifications. If the modem is restarted (CFUN=0, CFUN=1), then you need to reregister for the eDRX events and reset the eDRX call values as well.

RE: nRF9160 and eDRX mode on LTE-M connection

Achim Kraus — Wed, 21 Aug 2024 09:05:44 GMT

AFAIK, eDRX applies in RRC idle and supports larger receiver intervals there.

Once the modem enters "deep sleep mode" eDRX is not longer applied.

GSMA - Improving Energy Efficiency for Mobile IoT, March 2022

And yes, the eDRX status notifications may be mixing up, e.g. if you request to disable it, you don't get a "finally disabled" notification.

I haven't tested, what happens, if a device moves from a eDRX supporting network to a not supporting network. Nor if there is a eDRX notification after the +CEREG.

Lot's of good question.

But XMODEMSLEEP will be the wrong path ...

RE: nRF9160 and eDRX mode on LTE-M connection

bjornolav — Wed, 21 Aug 2024 07:11:00 GMT

Thank you Kazi

Does CEDRXS give the the current eDRX value or just the value we have requested. The documentation say:

"The command is used to read the requested eDRX parameters."

The XMODEMSLEEP seems to be promising.

RE: nRF9160 and eDRX mode on LTE-M connection

Kazi Afroza Sultana — Tue, 20 Aug 2024 15:58:39 GMT

Helo Bjørn,

I have talked to our team. I got some feedback.

You can either check via CEDRXS at command (which is the one you also get with LTE_LC_EVT_EDRX_UPDATE), or via XMODEMSLEEP as described here:https://devzone.nordicsemi.com/support-private/support/283529#permalink=750997

RE: nRF9160 and eDRX mode on LTE-M connection

bjornolav — Tue, 20 Aug 2024 13:40:15 GMT

Hi Kazi

We set eDRX parameter through AT commands:

sprintf(atCmdEdrx,"AT+CEDRXS=%s,4,\"%s\"", mode, strEdrx);

sprintf(atCmdPtw,"AT%%XPTW=4,\"%s\"", strPtw);

nrf_modem_at_cmd(reply, 100, atCmdEdrx);

nrf_modem_at_cmd(reply, 100, atCmdPtw);

This seems to work fine in most cases. We got some more information since I asked the question from the telecom provider. The sim cards we use gives us access to both Telia and Telenor networks. The profile on Telia did not have eDRX tuned on while Telenor had turned it on.

My question is how we can detect missing eDRX in the future? Is using LTE_LC_EVT_EDRX_UPDATE event as safe method? When reading the documentation, I see other methods but the impression that they just return our settings and not what the telecom operator really offers.

Best regards

Bjørn

RE: nRF9160 and eDRX mode on LTE-M connection

Kazi Afroza Sultana — Tue, 20 Aug 2024 13:19:59 GMT

Hello Bjørn,

Which samples you are following?

How have you configured the eDRX mode in config life? Could you please show how you handle this LTE_LC_EVT_EDRX_UPDATE event in the callback function?

Thanks.

Kazi