Section: 5.5.2.5.2 Source RAN to Target RAN Inter RAT handover Cancel
Content: Figure 5.5.2.5.2-1: Inter RAT handover Cancel 1. The source RAN decides to cancel the previously requested relocation of Handover resources. This may be due to not enough accepted bearers, UE returned to source cell or any other reason. 2. The source RAN sends a Cancel message with a Cause to the source EPC node (SGSN or MME). If the source RAN is: a) BSS the message sent is PS Handover Cancel (Cause), b) RNC the message sent is Relocation Cancel (Cause), or c) eNodeB the message sent is Handover Cancel (Cause). 3. The source EPC node terminates the relocation towards the target side by sending a Relocation Cancel Request (IMSI) message to the target EPC node. The Source EPC node also resumes operation on the resources in the source side. 4. The target EPC node triggers the release of resources in the target RAN and also releases its own resources allocated for this handover. 5. This step is only performed for Serving GW relocation. The Target EPC node deletes the EPS bearer resources by sending Delete Session Request (Cause) messages to the Target Serving GW. The Target Serving GW acknowledges with Delete Session Response (Cause) messages. 6. The target EPC node acknowledge the release of all resources on the target side by returning a Relocation Cancel Response (Cause) message to the source EPC node. 7. The source EPC node returns a Cancel acknowledge message to the source RAN. If the source RAN is: a) BSS there will be no acknowledge message sent to the source BSS, b) RNC the message sent is Relocation Cancel Acknowledge (Cause), or c) eNodeB the message sent is Handover Cancel Acknowledge (Cause). 8. If indirect forwarding tunnel is setup during handover preparation then cancellation of handover triggers the source MME/SGSN to send a Delete Indirect Data Forwarding Tunnel Request message to the S-GW to release the temporary resources used for indirect forwarding. 9. If indirect forwarding tunnel is setup during handover preparation and serving GW is relocated then cancellation of handover triggers the target MME/SGSN to send a Delete Indirect Data Forwarding Tunnel Request message to the S-GW to release the temporary resources used for indirect forwarding.