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HO: If target ENB is not serviced by source MME then How source MME sends HO request?

+1 vote
HO: If target ENB is not serviced by source MME then How source MME sends HO request?
posted May 24, 2019 by Bharat Kumar

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2 Answers

+2 votes

The S10 allows the source MME to talk with the Target MME who then forwards the message to the target eNB. The following is the path and link designation over which the message travels.

Source eNB ->S1MME-> Source MME =>S10=>Target MME -> S1MME-> Target eNB

Key - S1MME uses the S1AP protocol
- S10 Uses the GTPv2 protocol

answer May 24, 2019 by Charles Libby
+1 vote

When MME receives Handover required message with the target eNodeB Id which is not being served by it, it tries to get target MME which is serving to target eNodeB Id. I think it is vendor specific implementation how they manage this kind of resolutions in their network.
If source MME gets the details of target MME, it starts exchanging the handover signalling messages over the S10 link. Please go through 29.272 specification to get more details on S10 based handover signalling.

answer May 24, 2019 by Vikram Singh
Similar Questions
+2 votes

Is it possible, source eNodeB has received "handover command" message from MME and now it want to cancel handover procedure ?
What could be the possible reasons when source eNodeB want to cancel ongoing handover procedure ?

+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.

0 votes

When target eNodeB is not able to allocate resource for all the bearers which comes as part of Handover Request message, it sends handover request ack with partial success since "E-RABs Failed to Setup List" is present in HOReqAck message.
What MME or source eNodeB does in that case ? Does any action taken by MME for the E-RABs which failed to setup at target eNodeB or some other actions taken ?