Section: D.3.7.3 Execution phase
Content: Figure D.3.7.3-1: E-UTRAN to GERAN A/Gb mode Inter RAT HO, execution phase The source eNodeB continues to receive downlink and uplink user plane PDUs. 1. The Source MME completes the preparation phase towards Source eNodeB by sending the message Handover Command (Target BSS to Source BSS Transparent Container (PS Handover Command with RN part and EPC part), Bearers Subject to Data Forwarding List). The "Bearers Subject to Data forwarding list" may be included in the message and it shall be a list of 'Address(es) and TEID(s) for user traffic data forwarding' received from target side in the preparation phase (Forward Relocation Response message (Step 8)). Source eNodeB initiate data forwarding for the bearers specified in the "Bearers Subject to Data Forwarding List". The data forwarding goes directly to target SGSN decided in the preparation phase. 2. The Source eNodeB will give a command to the UE to handover to the Target Access System via the message HO from E-UTRAN Command. This message includes a transparent container including radio aspect parameters that the Target BSS has set-up in the preparation phase (RN part). This message also includes the XID and IOV-UI parameters received from the Target SGSN (EPC part). Upon the reception of the HO from E-UTRAN Command message containing the Handover Command message, the UE shall associate its bearer IDs to the respective PFIs based on the relation with the NSAPI and shall suspend the uplink transmission of the user plane data. NOTE 1: This step is unmodified compared to clause 5.5.2.3.3. The target SGSN acts as the new SGSN. 3. If the PLMN has configured Secondary RAT usage data reporting and the source eNodeB has Secondary RAT usage data to report, the eNodeB sends the RAN Usage data report message (Secondary RAT usage data) to the MME. Since the handover is an inter-RAT handover, the MME continues with the Secondary RAT usage data reporting procedure as in clause 5.7A.3. The reporting procedure in clause 5.7A.3 is only performed if PGW secondary RAT usage reporting is active. NOTE 2: The source eNodeB does not send any RAN context towards the target BSS. 4. The MS executes the handover according to the parameters provided in the message delivered in step 2. The procedure is the same as in step 6 in clause 5.1.4.2 in TS 43.129[ None ]  [8] with the additional function of association of the received PFI and existing RAB Id related to the particular NSAPI as described in clause 4.4.1 in TS 43.129[ None ]  [8]. The UE locally deactivates ISR by setting its TIN from "RAT-related TMSI" to "GUTI", if any EPS bearer context activated after the ISR was activated in the UE exists. 5/7. After accessing the cell using access bursts and receiving timing advance information from the BSS in step 2, the MS processes the NAS container and then sends one XID Response message to the new SGSN. The MS sends this message immediately after receiving the Packet Physical Information message containing the timing advance or, in the synchronised network case, immediately if the PS Handover Access message is not required to be sent (see clause 6.2 in TS 43.129[ None ]  [8]). Upon sending the XID Response message, the MS shall resume the user data transfer only for those NSAPIs for which there are radio resources allocated in the target cell. For NSAPIs using LLC ADM for which radio resources were not allocated in the target cell the MS may request for radio resources using the legacy procedures. NOTE 3: If the new SGSN indicated Reset (i.e. reset to default parameters) in the NAS container for PS HO included in the Handover from UTRAN Command message (UTRAN) or the Handover from GERAN Iu Command message, in order to avoid collision cases the mobile station may avoid triggering XID negotiation for any LLC SAPI used in LLC ADM, but wait for the SGSN to do so (see step 12). In any case the mobile station may avoid triggering XID negotiation for any LLC SAPI used in LLC ABM, but wait for the SGSN to do so (see step 12a). NOTE 4: This step is unmodified compared to pre-Rel-8. The message "HO from E-UTRAN Command" acts as the "Handover from UTRAN Command" message (UTRAN) or the "Handover from GERAN Iu Command" message. 6. Upon reception of the first correct RLC/MAC block (sent in normal burst format) from the MS the target BSS sends a PS Handover Complete (Local TLLI, Handover Complete Status) message to inform the new SGSN that the MS has arrived in the target cell. Each uplink N-PDU received by the new SGSN via the target BSS is then forwarded directly to the GGSN. A timer in source MME is started to supervise when resources in Source eNodeB and Source Serving GW shall be released. NOTE 5: This step is unmodified compared to pre-Rel-8. The PDN GW acts as the GGSN. 8. Upon receiving the PS Handover Complete message, the new SGSN send a Forward Relocation Complete message to the old SGSN to indicate completion of the PS handover procedures. The old SGSN responds with a Forward Relocation Complete Acknowledge message. For all bearers that were not included in the Forward Relocation Request message sent in step 3, the old SGSN now releases them by sending a Delete Bearer Command to the SGW, or, the appropriate message to the SCEF. NOTE 6: This step is unmodified compared to pre-Rel-8. The Source MME acts as the old SGSN. 9/11. The new SGSN sends an Update PDP Context Request (new SGSN Address, TEID, QoS Negotiated) message to the GGSN concerned. The GGSN updates the PDP context fields and returns an Update PDP Context Response (TEID) message. From now on the GGSN sends new incoming downlink IP packets to the new SGSN instead of to the old SGSN. The PDN GW shall include a Charging Id to be used at the SGSN as the Charging ID for reporting usage for this PDP context. The PDN GW shall include the Charging Id in the offline charging data. NOTE 7: This step is unmodified compared to pre-Rel-8. The Source MME acts as the old SGSN, and the PDN GW acts as the GGSN. 12. If the new SGSN indicated Reset (i.e. reset to default parameters) in the NAS container for PS HO included in the Handover from UTRAN Command message (UTRAN) or the Handover from GERAN Iu Command message, then on receipt of the PS Handover Complete the new SGSN initiates an LLC/SNDCP XID negotiation for each LLC SAPI used in LLC ADM. In this case if the SGSN wants to use the default parameters, it shall send an empty XID Command. If the new SGSN indicated 'Reset to the old XID parameters' in the NAS container for PS HO, no further XID negotiation is required for LLC SAPIs used in LLC ADM only. NOTE 8: This step is unmodified compared to pre-Rel-8. The message "HO from E-UTRAN Command" acts as the "Handover from UTRAN Command" message (UTRAN) or the "Handover from GERAN Iu Command" message. 12a. The new SGSN (re-)establishes LLC ABM for the PDP contexts which use acknowledged information transfer. During the exchange of SABM and UA the SGSN shall perform LLC/SNDCP XID negotiation. 13. The MS sends a Routing Area Update Request (Old P-TMSI, Old RAI, Old P-TMSI signature, Update Type) message to the new SGSN informing it that the source cell belongs to a new routing area. The MS shall send this message immediately after message 5, see TS 23.060[ General Packet Radio Service (GPRS); Service description; Stage 2 ]  [7]. The new SGSN knows that a handover has been performed for this MS and can therefore exclude the SGSN context procedures which normally are used within the RA Update procedure. For a MS supporting CIoT EPS Optimisations, the MS uses the PDP context status information in the RAU Accept to identify any non-transferred bearers that it shall locally release. For further descriptions of the Routing Area Update procedure see TS 43.129[ None ]  [8], clauses 5.5.2.3 and 5.6.1.1.1. NOTE 9: The RAU procedure is performed regardless if the routing area is changed or not, as specified by TS 43.129[ None ]  [8]. 14. When the timer started at step 8 expires, the source MME sends a Release Resources message to the source eNodeB. The Source eNodeB releases its resources related to the UE. Additionally, the source MME deletes the EPS bearer resources by sending Delete Session Request (Cause, Operation Indication, Secondary RAT usage data) messages to the Serving GW. The operation Indication flag is not set, that indicates to the Serving GW that it shall not initiate a delete procedure towards the PDN GW. Secondary RAT usage data was included if it was received in step 3a. The Serving GW acknowledges with Delete Session Response (Cause) messages. If ISR is activated then the cause indicates to the old Serving GW that the old Serving GW shall delete the bearer resources on the other old CN node by sending Delete Bearer Request message(s) to that CN node. 15. When the timer started in step 8 expires and if resources for indirect forwarding have been allocated then they are released.