How to set the RRC Idle Paging Interval?

[Dave_couling]

I'm strugglgin to find any documentation on how to set/request the iDRX paging interval in RRC idle.  I have a device which sends an MQTT keepalive message every 3minutes, so I'm trying to set the iDRX paging interval to match my MQTT keep alives to reduce power consumption.  However I can't find  any info on how to do this?  which API/library to use..etc

Thanks for your help guys,

DC

[Øyvind]

Hello DC, 

Due to Christmas holidays our technical support team is lower staffed, and the response time will be longer. Also, most of our R&D our out of office until January 4th. We apologize for any inconvenience this may cause.

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Do you mean eDRX? You can read more about the difference on eDRX and PSM here. Both can be set using AT commands i.e. +CEDRXS or +CPSMS.

Kind regards,
Øyvind

[Dave_couling]

I'm referring to the iDRX time to get the modem into RRC Idle from RRC Connected.  Its the timer I set in the Power Profilers

[Øyvind]

Under the User Guide of the Power Profiler, it states:

RRC inactivity timer: Decides how long the UE is required to stay in RRC connected mode before it can enter RRC idle mode (eDRX idle) or PSM. This is to avoid having to set up a new RRC connection immediately if there is a pending ACK or more data to be received from the network. This is decided by the network, and cannot be requested by the UE.

From LTE Quick Reference guide:
"There are largely two types of DRX in LTE.
One is Idle mode DRX. This idle mode DRX is more commonly known as Paging Cycle which is explained in detail in Paging page. The other type is called C-DRX (Connected Mode DRX) which is described in C-DRX page.

eDRX is a mechanism that can extend the cycle (sleeping duration) of these two DRX (Idle mode DRX and C-DRX).

Translated: 

There are two kinds of DRX, idle and connected. They have values provided by the network. eDRX can then be applied to "extend" the DRX duration. As we, and most network providers, only support extending the idle DRX we only talk about eDRX in terms of RRC idle mode. In reality it's extended idle DRX

More documentation can also be found under 3GPP Rel. 13, and the Rohde & Schwarz White Paper on Power Saving mode in LTE-M and NB-IoT

Hope this clears the confusion. 

Kind regards,
Øyvind

[sjacobsen]

I have a nRF9160 attached to a CMW500 with paging set to 1.28s.  I've deselected the "Keep RRC Connection" so that the RCC drops into the idle state. I am seeing an RRC jump into a connected state about every 8 seconds, though.  Is this normal or have I misconfigured my CMW500?  Here's a capture of the current consumption:

[sjacobsen]

I believe I’ve resolved this. T3412, the periodic tracking area updates, was enabled at 6 seconds. Once disabled, the 8 second connection states disappeared and the device stays in idle.