NB entity with the message S1-AP SWITH PATH REQUEST ACK to acknowledge the request. 15) The target eNB entity informs the source eNB entity that the handover was achieved with the message X2-AP EU CONTEXT RELEASE SO that it releases the context associated with the mobile. Handover 7.2.2. Handover based on X2 with relocation The functional architecture of the handover based on X2 with relocation of the SGW entity is shown in Figure 7.3. The X2-based handover procedure with relocation of SGW entity for the completion phase is illustrated in Figure 7.4. E-UTRAN Source Former LTE-Uu S1-MME S1-MME LTE-Uu Target Figure 7.3. Handover based on X2 with relocation functional architecture The preparation and execution phases are identical to those described for the handover based on X2 without relocation. 1) The target eNB entity starts the completion phase and transmits to the MME entity the message S1-AP SWITH PATH REQUEST containing TEID and ECGI identifiers. 2) The MME entity determines that the SGW entity must be relocated and transfers this information as well as the IP address of the entity PGW to the new SGW entity in the message GTPv2-C CREATE SESSION REQUEST. VoLTE and ViLTE 3) The new SGW entity forwards the ECGI identifier of the cell to the PGW entity in the message GTPv2-C MODIFY BEARER REQUEST that contains the TEID identifier that the PGW entity will use when it sends traffic to the new SGW entity. 4) The PGW entity forwards the ECGI identifier of the cell to the PCRF entity in the DIAMETER CCR message. Source Target Former Traffic S1 Bearer S5 Bearer Incoming data X2 Bearer Radio Bearer Radio Bearer S1 Bearer S5 Bearer Traffic Outgoing data S1-AP PATH SWITH REQUEST GTPv2-C CREATE SESSION REQUEST GTPv2-C MODIFY BEARER REQUEST DIAMETER CCR DIAMETER CCA GTPv2-C MODIFY BEARER RESPONSE GTPv2-C CREATE SESSION RESPONSE S1-AP PATH SWITH REQUEST ACK Traffic Bearer Radio Bearer S1 Bearer S5 Incoming data Bearer Radio Bearer S1 Traffic Bearer S5 Outgoing data X2-AP UE CONTEXT RELEASE GTPv2-C DELETE SESSION REQUEST GTP