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Why UE sends RRC Connection Request followed by EUTRA triggered RRC Connection Release?

+5 votes
874 views

I have scenario where in I have to gracefully shutdown/disconnect all UE's in connected state at RRC and go for reboot of the complete system. Here are the steps that I have followed -
1. Find all UE's in RRC which are in connected state
2. Send UE Context Release Request to MME for the UE with Cause as Misc_Cause_O_M_Intervention.
3. Once we receive UE Context Release Command from MME, Start UE Release procedure at eNodeb.
4. When we send RRC Connection Release Use Cause as "other"
5. Send UE Context Release Complete to MME.
6. Repeat Above steps for all UE's.
7. Go for reboot.

Here in this scenario, after sending RRC Connection Release to UE, it is immediately trying to connect to eNodeb with message RRC Connection Request with establishmentCause as "HighPriorityAccess" and MME is releasing the UE again.

I wanted to know why UE is trying to connect again.

FYI: UE was just in connected state and it was doing any data transfer (Both in Uplink and Downlink).

posted Oct 29, 2014 by Nagaraja Sadar

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1 Answer

+1 vote

In 3GPP Release 10, RRC specs has introducted "extendedWaitTime-r10" IE within the "RRC connection Release" message. EnodeB uses this IE to ask UEs, not to send RRC connection request till the duration assigned to "extendedWaitTime-r10" . It ranges from 1 to 1800 seconds.
I am not sure which software version you are using in both the sides UE as well as eNodeB. However, MME' NAS layer has provision in detach request (network to UE side).
In the network to UE direction:
Bits
3 2 1
0 0 1 re-attach required
0 1 0 re-attach not required
0 1 1 IMSI detach
1 1 0 reserved
1 1 1 reserved
By using "re-attach not required" cause, MME can ask to UE not try re-attach to the network.

answer Oct 29, 2014 by Vimal Kumar Mishra
Can you let me know the specific 3Bit IE which is sent by MME inside detach request
Similar Questions
+4 votes

There are couple of procedures are defined which consist of NAS as well as RRC signalling messages exchange.
Some of the NAS message sends to an UE through RRC Connection Reconfiguration message as piggybacked and some as DL Info transfer.

I want to know, Is there any procedure exists in lte when an UE receives RRC Connection Reconfiguration along with NAS message and responds back to network with NAS message first and then Reconfiguration Complete to eNodeB.

Usually, I saw UE sends RRC Connection Reconfiguration Complete message first then NAS response message.

+1 vote

Usually, I always saw when UE sends "S-TMSI" in RRC connection Request message then it definitely sends "Registered MME Information " in RRC Connection Setup Complete message.

I am looking for a scenario on which UE sends "Random number" in RRC Connection Request message and "Registered MME Information" in RRC Connection Setup Complete message.

+2 votes

During attach procedure, UE sends "Attach Request" along with "RRC Connection Setup Complete", eNodeB sends "Attach Accept" along with "RRC Connection Reconfiguration then why UE does not send "Attach Complete" along with "RRC Connection Reconfiguration Complete" message ? What could be the reason for defining the messages so ?

+2 votes

Please can anyone explain me,
In which Scenario, eNB send Idlemodemobilitycontrolinfo IE with release cause "other" inside RRC CONNECTION RELEASE message to UE???

0 votes

Hi,

this is the scenario:

  1. UE is attached to an eNodeB
  2. UE performs (or not performs, it's the same) UL/DL data traffic
  3. After a few seconds: on UE I see on display that icon signal it is emptying. There is no signal anymore. UE doesn't send any particular message.
  4. Network side, I see that eNodeB sends to MME a "UE context release request" with cause "radio connection with UE lost" or "user inactivity" (also when UE is downloading/uploading!!!).
  5. As result, UE is no more able to attaches to eNodeB again: it is necessary the airplane mode to initiate the attach procedure again.

I think that UE loses the signal after eNodeB sends the "UE context release request"...

Whose fault is it?
Is device faulty? Because the problem is not present for other devices...
Or is eNodeB faulty? Because the problem is not present under another eNodeB.

I don't understand. Sorry and thank you if you'll answer.

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