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UE context release request and signal loss

0 votes


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.

posted Feb 18, 2021 by Jane Austen

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Do you have wireshark log for the analysis ?

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+1 vote


In LTE, while UE makes an RRC Connection attempt and in the followed by procedures, if S1AP: Initital Context Setup Request is BLOCKED from MME to eNB, then what eNB should do ideally?

Should it do UE context release, if Initial Context Setup Request message is not received at aNB?

+5 votes

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).

+2 votes

when mme will change the security keys and send it in ue context modification request 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 ?