LTE S1 Handover Flow

These diagrams detail the LTE S1 handover, used when no X2 interface links the source and target eNodeBs. Debugging a handover capture? VisualEther renders the S1AP and NAS signaling from a Wireshark PCAP as a sequence diagram, so you can see exactly where the handover broke.

LTE S1 Handover Flow

UE is handed over using an S1 handover if the X2 interface is not available between the source and target eNodeB

Source eNodeB role in S1 handover

Message interactions involving the eNodeB that was serving the UE at the time of handover

Target eNodeB role in S1 handover

Message interactions involving the eNodeB that will be serving the UE after the handover

MME role in an S1 handover

Understand the role of the MME in the S1 handover procedure