Question: During an X2 handover, if the source eNB has the UE NR security capabilities, what action should the source eNB take with regards to these capabilities?
Option 1: Drop the UE NR security capabilities to ensure compatibility with older MMEs.
Option 2: Send the UE NR security capabilities to the target eNB in the X2 handover request.
Option 3: Modify the UE NR security capabilities based on E-UTRAN security algorithms before sending to the target eNB.
Option 4: Ignore the UE NR security capabilities and rely on the target eNB to create them from E-UTRAN security algorithms.
Explanation: This is correct because, during X2 handovers between base stations (eNBs), if the source eNB has the UE's NR security capabilities, it should forward these to the target eNB. This ensures seamless secure communication continuity for the UE post-handover, using the same security algorithms without needing recreation based on E-UTRAN algorithms at the target eNB.