eDRX mode doesn't work as expected

RE: eDRX mode doesn't work as expected

Carl Richard — Tue, 11 Aug 2020 07:43:03 GMT

Hello again, Christian!

Good to hear that the information was helpful! I hope the answers from 1NCE can clear things up.

My apologies. The case in questions also covers eDRX problems. One possible issue uncovered was that PSM was enabled in addition to eDRX, which in turn forces the device to sleep after a designated active time. This could impose unexpected eDRX behavior.

A command sequence was presented in order to check if eDRX is enabled properly. It is shown below. Please make sure you are running the Serial LTE Modem application and latest mfw that suits you when running the commands:

AT#XSLMVER

AT+CGMR

AT%XSYSTEMMODE=1,0,0,0

AT+CEREG=5

AT+CFUN=1

//wait to get connected

AT+CGDCONT?

AT%XMONITOR

AT+CPSMS=0

AT%XMONITOR

AT+CEDRXS=2,4,"0101"

AT%XPTW=4,"0001

AT+CEDRXRDP

AT#XSLEEP

Hope this can be of use!

Best regards,
Carl Richard

RE: eDRX mode doesn't work as expected

Christian22 — Thu, 06 Aug 2020 21:19:47 GMT

Hello Carl,

Thanks a lot. Good to know that the application works as expected. In order to be able to compare the results on the same technology I also tested the application on LTE-M (still using the same 1NCE SIM) and got an eDRX cycle of about 1.3s.

The possibility that the missing eDRX feature could also be a limitation of 1NCE is actually a very helpful information. I will definitely contact them in order to find out where the limitation comes from.

Unfortunately, the case you linked to is private. Therefore I have no access to it. Would it be possible to get a summary or an extract out of it?

Thank you very much for your support.

Christian

RE: eDRX mode doesn't work as expected

Carl Richard — Thu, 06 Aug 2020 10:53:23 GMT

Hello, Christian!

I tested your application here and managed to achieve the desired eDRX configuration. However, the test was performed on a LTE-M network, opposed to NB-IoT, but it proves that your implementation functions at least. This in turn makes me believe that there are some limitations with your SIM-provider, 1NCE. Even though the network provider (in this case Deutsche Telekom) supports eDRX we have seen in other instances that a third party SIM-provider not necessarily supports the feature.

I recommend that you query 1NCE about this.

Also, make sure that PSM is disable as this restricts how long the device actually is using eDRX. This case mentions this.

BR,
Carl Richard

RE: eDRX mode doesn't work as expected

Christian22 — Wed, 05 Aug 2020 15:41:15 GMT

Hello Hakon,

Sorry for the delay. My original post already contains almost the full code. I wanted to keep it as simple as possible to be sure that the application doesn't influence the behavior of the NB-IoT connection by sending messages in the background such as the heartbeat used in MQTT. Therefore I only configured an eDRX cycle of 20s and established a connection and that's it.

Attached you will find the whole project, the link monitor log and a picture which shows how the consumption over time looks like.

For your information, in the log-file I removed the header and replaced the cell ID and IMSI by Ys

eDRX_project.zip

eDRX_log.txt

By the way, in the meantime I got the information that it probably is an issue of the MNO as, most likely, eDRX is not supported. But it would be nice if you could take a look into my project and the log-file to be sure that it has nothing to do with my configuration.

RE: eDRX mode doesn't work as expected

Hakon — Wed, 29 Jul 2020 09:04:20 GMT

Hello,

can you show me the link monitor log? That would be very helpful. And if possible, sharing the full code wouldn't hurt either.

RE: eDRX mode doesn't work as expected

Christian22 — Wed, 22 Jul 2020 16:00:43 GMT

Does anyone has a similar problem?

It would already be helpful if someone can tell me if I made a mistake in the test application shown above.