How to request iDRX interval?

[charleshaf]

On the Online Power Profiler I noticed changing iDRX interval has a significant effect on power consumption. How can I adjust this interval on our device?

I saw this ticker that never got answered: devzone.nordicsemi.com/.../how-to-set-the-rrc-idle-paging-interval

[charleshaf]

Looking at the nrf9160 SIP with SDK 2.6.1

[Mariano Goluboff]

The iDRX interval in the Online Power Profiler (OPP) is the same as the eDRX cycle time. You can learn more about eDRX and PSM in the Cellular IoT Fundamentals course at the Developer Academy:

https://academy.nordicsemi.com/courses/cellular-iot-fundamentals/

Take a look at the section called "Power saving techniques" in Lesson 1.

The application can request a specific eDRX cycle time, but in the end it is the network that will give the modem the actual value, so you should monitor what is assigned by the network.

There are different ways to set the requested time in your application. If you're using the LTE Link Control library, you can set it at compile time with `CONFIG_LTE_EDRX_REQ_VALUE_LTE_M`, or you can set it at run time with `lte_lc_edrx_req()`:

https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/libraries/modem/lte_lc.html#enabling_power-saving_features

If you're using AT commands directly, you can use the `AT+CEDRXS` command.

[Edit to add blog link]

You should also take a look at this blog:  Maximizing battery lifetime in cellular IoT: An analysis of eDRX, PSM, and AS-RAI

There is an additional function, AS-RAI, that some networks support and allow you to go into RRC Idle faster than having to wait for the network's RRC inactivity timer.

[charleshaf]

Thanks for your answer!

 Maximizing battery lifetime in cellular IoT: An analysis of eDRX, PSM, and AS-RAI 

I see in that article it says "AS-RAI was introduced in 3GPP release 14 for both LTE-M and NB-IoT, and it can save a lot of power consumption if supported by the network."

But looks like AS-RAI is just for NB-IoT and doesn't work with LTE-M. Seeing this log 

"<err> lte_lc: RAI not supported for LTE-M networks"

[Mariano Goluboff]

Versions of the SDK prior to 2.7.0 don't have support for lte_lc_rai_req() for LTE-M. Instead, you need to use AT commands to use AS-RAI.

If you upgrade to 2.7.0, you can use lte_lc_rai_req().