LTE : What MME will do if handover gets failed ?

Question

I have two use cases for handover failures:
1. Handover command has been sent out to UE by source eNodeB and UE does not latch on either of the eNodeBs source eNodeB as well as target eNodeB . What the action would be taken by MME , source eNodeB and target eNodeB ?
2. Handover command has been sent out to UE by source eNodeB and UE does not latch on the target eNodeB while it comes back to the source eNodeB using RRC reestablishment procedure ? What the action would be taken by MME , source eNodeB and target eNodeB ?

Answer 1

Scenario 1 when UE is not latching on source eNB or target eNB .
Source eNB starts tcrelocoverall timer after getting ho command so in this case source eNB will no get any UE context release from MME before t relocoverall then after t relocoverall expiry source eNB should release the UE context and should send UE context release to mme. MME also release the UE context and should send UE context release to target eNB . then target eNB shall release the UE context.

1. In second scenario if UE latching to source eNB before expiry of t relocoverall then UE continue with source eNB and source eNB shall send ho cancel to mme. Then MME shall send UE context release to target eNB .

Comments

Thanks Veer Pal Singh Yadav to share your inputs.

Answer 2

Hi Veer Pal ,
couldn't understand what you explained for 1st scenario (when UE is not latching on source eNB or target eNB) . Can you explain it again.

Thanks & Regards.

Comments

Can you pls provide detail what is ur doubt.