nrf9160 - can not set PSM

[SilasV]

Hi 

I am working on testing the PSM on my nrf9160 custom board using SLM 

After powering up and setting AT+CFUN=1, when I send the following AT commands:

AT+CPSMS=1,"","","10101010","00100001"
OK
AT+CPSMS?
+CPSMS: 1,,,"10101010","00100001"
OK
AT+CEREG?
+CEREG: 5,5,"590C","03BE4711",7,,,"11100000","11100000"
OK
AT%XMONITOR
%XMONITOR: 5,"Sprint","Sprint","310120","590C",7,25,"03BE4711",108,8665,24,34,"","11100000","11100000","01001001"
OK

It seems the network is not setting the requested PSM timer values - the returned values start with "111" - which means the timer is deactivated. 

Can anyone help me please?

Thanks

[Albrecht Markus Schellenberger]

Hello Silas,

I can confirm that you are not getting any Active-Time from the network operator and thus, no PSM neither.

My suspicion is that the network operator your SIM card is registered to might not support PSM, unfortunately. You have to check with them!

Regards,

Markus

[SilasV]

Thank you Markus for your prompt reply!

That may be the issue. 

So I am now thinking of approach of putting the nRF9160 to Sleep after use periodically.  I will run the tests in that direction and see how it goes. That way at least our devices will be independent of the PSM feature, since the devices are using with the roaming feature and not sure which network provider will be used at any given time. 

Would you please share any ideas on the above approach?

Thanks

[Albrecht Markus Schellenberger]

Hello Silas,

the approach here depends of course on the purpose and requirements of your application.

However, disconnecting the device from the network and putting it into sleep might be an alternative way to go. But it is very likely that a reconnect of the device to the network will consume more power compared to the usage of PSM.

We have an Online Power Profiler for LTE tool available, which you might be interested in to use as a reference?

Another option might be to change to a network provider supporting PSM.

I hope this will help you!

Regards,

Markus

[SilasV]

Hi Markus

Thank you so much for your reply.

Although for our devices we have the sleep time configurable (which can be set from 15min to 60min), it still does make sense to use PSM when the sleep time is small enough. The active time is not expected to be more than 7 to 10sec depending on the size of the data packet.  I will try and find out if the network provider can help for activating the PSM/eDRX.

Just to confirm a few more questions:

1. Do I need to use any particular band to be able to use PSM/eDRX feature? or is this available for all the bands? May be I need to switch to that band where PSM is enabled. 

2. This is more general question: Do all the network providers implement the PSM/eDRX features? This seems to be a very particular requirement for NB-IoT for the battery/power saving.  Why would any network provider not provide this feature? 

Thanks 

SilasV 

[Albrecht Markus Schellenberger]

Hello Silas,

SilasV said:

1. Do I need to use any particular band to be able to use PSM/eDRX feature? or is this available for all the bands? May be I need to switch to that band where PSM is enabled. 

PSM is not depended on any particular band for a certain operator. It only depends on if the operator supports it or if it is part of the agreement between an MVNO (mobile virtual network operator) and the MNO (mobile network operator).

SilasV said:

2. This is more general question: Do all the network providers implement the PSM/eDRX features? This seems to be a very particular requirement for NB-IoT for the battery/power saving.  Why would any network provider not provide this feature? 

Not all network providers support PSM. As I already mentioned, it might not be part of the agreement if it is an MVNO. Some operators do not support it yet and some operators do not want that neither, because they do not want to buffer data from devices not reachable. For some operators, devices have to ask for TAU above a certain limit to be granted PSM (if the device requests a value below the limit, PSM will not be granted). You can check this link which gives you an overview of the Ibasis eSIM national coverage. It provides a list with operators as well and if PSM is supported or not.

Regards,

Markus