Abiding by the negotiated PSM/eDRX timing intervals

[Cody]

Hello,

I have been playing around with LTE PSM and eDRX modes and had some questions regarding configuration.

If I configure the PSM/eDRX timing windows, how do I know that I am conforming to the timing windows negotiated?
For example, if the device has negotiated a 240 minute PSM window, how do I know, from a software perspective when that 240 minute interval is active and I can send/receive data without it being considered "exception processing"? Do I attempt to negotiate PSM, validate that the carrier accepted my PSM configuration, then start a timer (in software) to know when it is valid to use the LTE modem?

Does the application get notified that my window is active and to proceed with any modem TX/RX at this time?
Essentially, I would like to ensure that the use of the modem is not violating the negotiated sleep interval (PSM/eDRX) and thus avoiding the risk of being put into an isolated sandbox.

Thanks,
Cody

[Øyvind]

Hello Cody, 
Sorry for the late reply. Are you working on the master branch or tag v1.1.0? Our Public APIs for the LTE Link Control driver found in nrf\include\lte_lc.h does have som API that may be useful. 

If I configure the PSM/eDRX timing windows, how do I know that I am conforming to the timing windows negotiated?

 For PSM please refer to AT+CEREG, and for eDRX please refer to eDRX Settings: AT+CEDRXS + eDRX Dynamic Parameters: AT+CEDRXRDP.

Another AT command that might be of use is the AT%XMONITOR which combines several modem parameters.

For example, if the device has negotiated a 240 minute PSM window, how do I know, from a software perspective when that 240 minute interval is active and I can send/receive data without it being considered "exception processing"?

 We're working with a new API, and will be supported in the future. 

Do I attempt to negotiate PSM, validate that the carrier accepted my PSM configuration, then start a timer (in software) to know when it is valid to use the LTE modem?

 Yes, at the moment this might be the only workaround.

Does the application get notified that my window is active and to proceed with any modem TX/RX at this time?

 At the moment no, but this is a feature request reported internally as far as I know. No timeline. 

Essentially, I would like to ensure that the use of the modem is not violating the negotiated sleep interval (PSM/eDRX) and thus avoiding the risk of being put into an isolated sandbox.

 Yes, this is something we have got several requests about.

Kind regards,
Øyvind

[Cody]

Thank you Øyvind for your very detailed response, it was very helpful.
I see that nRF Connect SDK v1.2.0 RC1 has been cut, do you know if some of the items discussed in your response are scheduled to appear in v1.2.0 when released?

[Øyvind]

Hi Cody, 

nRF Connect SDK tag v1.2.0 is out now. 

I'm sorry, at this moment I do not know if they are included. 

Kind regards,
Øyvind

[DevinCallahan]

Is there an update on when the Active Time notification API will be available?

[Øyvind]

Hello @devincallahan, 

I recommend looking at our newest NCS, and its documentation. Current version is NCS v1.3.1. 

The lte_lc.h includes updated API and I encourage having a look at this as well.

If any further questions, please register a new ticket.

Kind regards,
Øyvind