Section: 5.5.2.5 Inter RAT handover Cancel 5.5.2.5.1 General
Content: Instead of completing the handover procedure, the source RAN node (eNodeB, RNC or BSS) may at any time during the handover procedure, up to the time when a handover command message is sent to the UE cancel the handover. The reason for cancelling may be e.g. due to a timer expiration or due to other events within the source RAN node and is initiated by sending a handover cancel PDU to the source EPC node (MME or SGSN). A handover cancel PDU shall also be sent by the source RAN node after a handover command message is sent to the UE for the case where the handover fails and the UE returns to the old cell or radio contact with the UE is lost. This is done in order to release the resources reserved for the Handover in the target system.