eDRX / PSM mode always on?

[Eirik Aa]

So I have a question about the nRF9160 when enabling the xDRX or PSM mode. Does one just turn the option on and leave it on eaven while uploading data or do you turn it off each time you want to send some data and communicate with a socket?

lte_lc_psm_req( );
lte_lc_edrx_req( );

And do you need to request it again after sending data?

[Martin Lesund]

Hi Eirik,

Concerning entering PSM or (e)DRX sleep:

The application do not need to do any other control than to set preferred sleep periods.

Modem will retain those settings and negotiate values based on those settings with the network whenever that is needed. It will also enter various sleep states when that is possible.

 

Please note that there is an active time after connection before we can enter PSM sleep, i.e. power consumption stays on the “idle DRX” level before we move to “PSM level”.

Value for this timer can be seen with negotiated PSM parameters. This can be done by "subscribing to unsolicited network status notifications"; command +CEREG using AT+CEREG=5.

Same command will also return the negotiated PSM sleep value that will be used by the modem once in idle mode and active time is over.

 

One thing to keep in mind is that the debugger will prevent modem from entering deep sleep.

There is no way to check the sleep level of the modem from application side.

 

Is the 25 seconds comment actually about eDRX sleep length? (i.e. you has not been able to get longer sleep cycle from the network even though you have set something longer as a parameter to modem?).

There is a possibility that your carrier provider have not implemented the eDRX/PSM schemes yet as well.

The possible sleep periods are also dependent on what the carrier support. (some can support longer than others)

Best Regards,
Martin L.

[Eirik Aa]

Thank you for the reply. It seems like eDRX is not currently supported all the way on my carrier but PSM mode seems to be working as expected.