NBIoT Timers

[Panagiotis Galiatsatos]

Hi, 

I need some help to interpret the LTE timers values that my network operator applies. 

1. During network registration I requested RPTAU : 10 min and AT : 0 min, by issuing CPSMS=1,"","","10101010","00000000".
   The network operator responded with: +CEREG:5,1,"1F40","030F9047",9,,,"00000000","11100000".
   The XMONITOR returns : %XMONITOR: 1,"COSMOTE@","","20201","1F40",9,20,"030F9047",,,,,"","00000000","11100000","00101101"
   
   It seems that the PTAU is disabled, which to my understanding means that there is no need for the UE to perform periodic tracking area update.
   Is my assumption true? Does the UE enters in PSM mode?
   
   
2. In the following figure, a transmission is captured. It can be seen that there is an idle period ~10sec after the Tx period.
   Searching through the posts I found this and this this in which the Inactivity Timer is mentioned.
   
   So I guess that this 10 sec period is the inactivity timer set by my network operator.
   Is there any AT command to read the Inactivity timer setting?
   (I also tried to enable the Release Assistance (AT%XRAI=3 / AT%XRAI=4), but I had no luck).
   

Thank you in advance.

Kind regards,

Panagiotis.

[Carl Richard]

Hello, Panagiotis!

1. You are correct that PTAU is disabled. This does in fact mean that the device was not granted PSM, and will thus not enter PSM. Which SIM-provider are you using and can you confirm that they support the PSM feature?

2. The idle period your are seeing is indeed the RRC Inactive Timer described in the posts you linked, and it is, as you say, given by the network operator. There is unfortunately no way to read this value yet, but your network provider should know which parameters they provide. Capturing a transmission, like you have done here, is also a viable way of determining the timer parameters. We have an online power profiler for LTE where you can read more about the different parameters and see how they affect the device.

I suggest that you ask your network operator about the XRAI feature aswell, as it's not neccessarily supported.

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I would like to see these things change for the better so that it will be easier for developers to predict the behavior of their devices, but alas, we're not there yet. 

Best regards,
Carl Richard

[Panagiotis Galiatsatos]

Hello Carl!

Thank for your response.

I will contact my network operator and I will be back!

Kind regards,

Panos.