The application sends downlink data.
The PGW forwards the data to the SGW. The SGW sends a Downlink Data Notification (DDN) message to the MME requesting that UE be paged.
The UE is in Power Saving Mode or Extended idle mode DRX, or the MME initiates paging for the UE but receives no response.
The MME sends a DDN failure indication to the SGW.
The MME notes the subscription option for notification of availability after DDN failure for the UE, and sets a Notify-on-available-after-DDN-failure flag. Not every DDN failure triggers this event. This event may be triggered only when the UE is in PSM or Extended idle mode DRX.
At some later time, the UE contacts the network (e.g. to perform a TAU, or a service request), or the UE becomes or is about to become reachable for paging (e.g. an eDRX Paging Transmission Window is reached).
The MME notes that UE is available and that the Notify-on-available-after-DDN-failure flag for the UE is set.
The MME sends a Monitoring Indication to the SCEF that the UE is available, according to clause 220.127.116.11
. The MME also resets the Notify-on-available-after-DDN-failure flag for the UE.
The SCEF notifies the application that the UE is available.
The application may decide to resend data it has for the UE.
UE transitions to idle mode according to TS 23.401
, e.g. CM-IDLE with PSM or eDRX.
If Idle Status Indication was requested during Monitoring Event configuration, and the MME/SGSN supports Idle Status Indication, then MME executes step 2a of clause 18.104.22.168
, and includes the time at which the UE transitioned into idle mode, its granted active time (if PSM is enabled), the periodic TAU/RAU timer granted to the UE by the MME, the eDRX cycle length (if extended idle mode DRX is enabled), and the Suggested number of downlink packets if a value was provided to the S-GW in the message.
The SCEF executes step 3 of clause 22.214.171.124
, and includes additional parameters specified in step 12 above.
The application may send queued data toward the UE.