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LTE: What may be the reason for S1 setup failure ?

+1 vote
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LTE: What may be the reason for S1 setup failure ?
posted May 5, 2014 by Ganesh Kumar

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1 Answer

+3 votes

The S1-Setup failure will happen with some cause. it can have many reasons and to specify that reason Failure message has one information element named as CAUSE. So this CAUSE IE is specified in

TS 36.416 Section 9.2.1.3

For instance i can explain with one example:
Suppose eNodeB has initiated a connection by sending a S1 setup Request message,including the TAC and the configured PLMN Identity included into the Broadcast.PLMNs IE,

  • MME responds with the S1 setup failure including the reason of the unsuccessful establishment (e.g unknown TAC, unknown PLMN Id, etc)
  • No resource is hold by any network element after the unsuccessful S1 establishment
answer May 22, 2014 by Hiteshwar Thakur
Similar Questions
+1 vote

Generally MME serves a group of tracking areas and belongs to at least one PLMN.
Lets assume, MME receives S1-setup request from eNodeB with the list of supported TAs.
Now, there are three possibilities as captured below.
1. All supported TAIs match at MME
2. Not even a single TAI match at MME
3. Few TAIs match at MME

I want to know, what MME will do for case 2 and case 3 ? How it will respond to eNodeB ?
If MME responds with S1-setup failure then what would be the cause value ? I did not find any reference in 36.413 for these scenarios.

+1 vote

In S1-Setup Request message, eNodeB tells max # (6) of broad casted PLMNs. In S1-Setup response message, MME responds back to eNodeB with maxnoofPLMNsPerMME(32) IE. I am not able to find the reason that why maxnoofPLMNsPerMME is 32 even eNodeB can broadcast maxium of 6 ?

0 votes

Hi All,

I have a query regarding S1 setup procedure.
If MME receives S1 setup Request message from same eNB twice (Assuming the S1 connection is already up), what will be the behavior of MME in this case.
Will it erase both UE and non-UE related application data? Or does it send S1 setup failure message?

Thanks in advance.

+2 votes

What is the eNB behavior in-case MME is not responding to S1 setup request message (ie. MME is not sending S1 setup failure or success).

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