How to know for which specific purpose RRC reconfiguration message is sent?

Specs & Protocol Testing
1

Hi Friends.
How to know for which specific purpose RRC reconfiguration message is sent?
Is there an IE inside the message that displays the reason like to change radio berar conditions, to perform handover, to change measurement related stuff or to change scell, etc?
How to understand the purpose?
Thanks in advance guys.

2

Hi. I think you can only check this by looking at content of the message.

Here is useful blog:

1 Like
3

Hi @ran_core_consultant, thanks.
It is ok to look at the content, but the issue is I checked but could not find any sign that indicates the cause of triggering an rrc reconfig message.
For example, think of rrc request message. It contains an IE that specified whether it is because of mo-data, mt access or signalling.
I am looking for this kind of IE. :frowning:

4

Can you post the snippet of RRC config message in question?
There is no such one IE available for RRC reconfiguration in LTE. Each procedure has its own IE. For ex, if the message is meant for HO, you will see mobilty configuration. If it is for CA, you will see IEs related to Scell addition etc.
One has to interpret from the message contents.

5

No, just RRC Reconfig message cannot tell you reason why it was triggered.
You need to see content of the messages and earlier messages to understand the reasons.
For instance if RRC-Reconfig is for measurement-config then its likely that eNb has seen a measurement report and UE needs to be prepared for HO.

6

Thank you @ran_core_consultant. I see what you mean now.
Need to check the content - no quick way!
Thanks so much.

Hi @pradeep, no specific message.
It was meant for a generic one.
But I am ok now with your explanations.
Thanks so much.

7

You can check the details of RRC Reconfig.
Details can be found in 3x.331 specs for respective RATs.

8

I am looking for any practical experience on that I check the message from wireshark.