v2-C DELETE SESSION RESPONSE Figure 7.4. Handover based on X2 with relocation completion phase 5) The PCRF entity responds to the PGW entity with the DIAMETER CCA message to acknowledge the request. 6) The PGW entity responds to the SGW entity with the message GTPv2-C MODIFY BEARER RESPONSE containing the TEID identifier that the new SGW entity will use when it sends traffic to the PGW entity. 7) The new SGW entity responds to the MME entity with the message GTPv2-C CREATE SESSION RESPONSE containing the TEID identifier Handover that the target eNB entity will use in the GTP-U header when sending traffic to the new SGW entity. 8) The MME entity responds to the target eNB entity with the message S1-AP SWITH PATH REQUEST ACK containing the TEID identifier provided by the new SGW entity. 9) The target eNB entity informs the source eNB entity that the handover was achieved with the message X2-AP EU CONTEXT RELEASE that it releases the context associated with the mobile. 10) The MME entity controls the release of the context of the former SGW entity with the message GTPv2-C DELETE SESSION REQUEST. 11) The former SGW entity responds to the MME entity with the message GTPv2-C DELETE SESSION REQUEST to acknowledge the request. 7.3. Handover based on S1 7.3.1. Handover based on S1 without relocation The functional architecture for the handover based on S1 without relocation of the MME and SGW entities corresponds to Figure 7.1, for which the X2 interface between the source and target eNB entities is deactivated. The MME is no longer transparent to the handover mechanism and acts as a signaling relay for the handover control between the source and target eNB entities. The temporary bearer built between the source and target eNB entities for incoming data passes through the SGW entity. The handover procedure based on S1 without relocation of the MME and SGW entities is given in Figure 7.5: - the preparation phase includes messages 1 to 6; - the execution phase includes messages 7 to 10; - the completion phase includes messa