Section: 5.3.4A Connection Suspend procedure
Content: This procedure is used by the network to suspend the connection if the UE and the network support User Plane CIoT EPS Optimisation (see TS 36.300[ Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 ]  [5]). Figure 5.3.4A-1: eNodeB initiated Connection Suspend procedure 1. The eNodeB initiates the Connection Suspend procedure to the MME, see TS 36.413[ Evolved Universal Terrestrial Radio Access Network (E-UTRAN); S1 Application Protocol (S1AP) ]  [36]. The eNodeB indicates to the MME that the UE's RRC connection is to be suspended upon which MME enters ECM-IDLE. Data related to the S1AP association, UE Context and bearer context, necessary to resume the connection is kept in the eNodeB, UE and the MME. If the eNodeB supports WUS, the eNodeB should include the Information On Recommended Cells And eNodeBs For Paging in the S1 UE Context Suspend Request message; otherwise, the eNodeB may include the Information On Recommended Cells And eNodeBs For Paging in the S1 UE Context Suspend Request message. If available, the MME shall store this information to be used when paging the UE. The eNodeB includes Information for Enhanced Coverage, if available, in the S1 UE Context Suspend Request message. If the PLMN has configured secondary RAT reporting and the eNodeB has Secondary RAT usage data to report, the Secondary RAT usage data is included. If Dual Connectivity was activated by that eNodeB at the time of the Connection Suspend or earlier by that eNodeB, the eNodeB shall include the last known PSCell ID and the time elapsed since the Dual Connectivity was released. If Service Gap Control is being applied to the UE (see clause 4.3.17.9) and the Service Gap timer is not already running, the Service Gap timer shall be started in the MME when entering ECM-IDLE, unless the connection was initiated after a paging of an MT event, after a TAU procedure without any active flag or signalling active flag set or after a TAU procedure for network access for regulatory prioritized services like Emergency services or exception reporting. 1a-d. If the eNodeB provided Secondary RAT usage data in step 1 and if PGW secondary RAT usage data reporting is active, the MME initiates the Secondary RAT usage data reporting procedure in clause 5.7A.3 as illustrated in figure 5.7A.3-2. 2. The MME sends a Release Access Bearers Request (Secondary RAT usage data) message to the Serving GW that requests the release of all S1-U bearers for the UE. If Secondary RAT usage data was received in step 1, Secondary RAT usage data is included in this message. The message indicates that the SGW is the target for the reporting. 3. The Serving GW releases all eNodeB related information (address and downlink TEIDs) for the UE and responds with a Release Access Bearers Response message to the MME. Other elements of the UE's Serving GW context are not affected. If downlink packets arrive for the UE, the Serving GW starts buffering downlink packets received for the UE and initiating the "Network Triggered Service Request" procedure, described in clause 5.3.4.3. NOTE: Based on operator policy any received Indication of "Abnormal Release of Radio Link" may be used by Serving GW in subsequent decisions to trigger PDN charging pause if the feature has been enabled on that PDN. The Serving GW informs the MME in the Release Access Bearer Response message about release of S1-U bearers. 4. The MME sends an S1AP: UE Context Suspend Response message to the eNodeB to successfully terminate the Connection Suspend procedure initiated by the eNodeB, see TS 36.413[ Evolved Universal Terrestrial Radio Access Network (E-UTRAN); S1 Application Protocol (S1AP) ]  [36]. 5. The eNodeB sends RRC message to suspend the RRC Connection towards the UE, see TS 36.300[ Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 ]  [5]). If Service Gap Control is being applied for the UE (see clause 4.3.17.9) and the Service Gap timer is not already running, the Service Gap timer shall be started in the UE when entering ECM-IDLE, unless the connection was initiated as a response to paging of an MT event, after a TAU procedure without any active flag or signalling active flag set or after a TAU procedure for network access for regulatory prioritized services like Emergency services or exception reporting.