Enable Release Assistance for PSM

[MJD093]

Hi,

I would like to check my understanding of PSM. Currently, using the AT Client on the local NB-IoT network, I can see that the device is entering PSM after 3 minutes of DRX.

What I would like is to remove this 3 minutes of DRX with release assistance but I was unable to do so. I tried setting the XRAI AT command before and after calling CPSMS but was not able to get the device to shutdown.

Is it possible to get the device to shutdown any faster as this was three minutes of 6.6mAs that I would like to save if possible.

I have set the PSM to 10 hrs TAU and 3 mins active. Is this just the active period's 3 minutes?

[Heidi]

Hi!

With PSM, you can request the parameters you want, but the network is free to reject them and set their own times. 

You can use AT%XMONITOR to read out the actual values set by the network as opposed to the requested values.

Did that answer your question?

Best regards,

Heidi

[MJD093]

Hi Heidi

I don't believe it is the network rejecting my parameters. I'm not able to test this from my current location but my question is more to do with if it is possible to enter PSM faster than the 3min delay I saw after signalling the network.

Is this because after setting PSM parameters, the device enters the requested active time before powering off or is it held active by the network in a similar fashion to the mechanics that release assistance is meant to allivate. I.e. after communicating with the network, the device is held in a mandatory DRX until the network releases the connection.

[Heidi]

You could request a shorter PSM active time with the +CPSMS command, and then PSM will activate faster? Does that work.

I would not recommend changing PSM settings constantly as change requires signaling towards the network and consumes more power than staying in RRC Idle state.

Release assistance could be used to speed up RRC Connection release but does not impact PSM active time which is started once RRC Connection is released. Release assistance should be used only when the application use-case is sending a single IP packet.