User's Manual

Ver.
CHAPTER 4. Message Flow
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1.0
Service Request by Network
The message flow for service request procedure by network is illustrated below.
Figure 17. Service Request Procedure by Network
Step Description
1)~2) When receiving a downlink data packet that should be transmitted to a UE while the
user plane is not connected to that UE, the S-GW transmits the Downlink Data
Notification message to the MME which has the control plane connection to that UE.
The MME issues the Downlink Data Notification Acknowledge message to the S-GW in
response.
If the S-GW receives additional downlink data packet for the UE, this data packet is
stored and no new Downlink Data Notification is transmitted.
3)~4) When the UE is registered to the MME, the MME transmits the PAGING message to all
Indoor Pico Cells that belong to the TA where the UE is registered. When the Indoor
Pico Cell receives the PAGING message from the MME, the Indoor Pico Cell transmits
the Paging message to the UE.
5) If the UE in idle mode is paged via the E-UTRAN connection, the Service Request
procedure is initiated by the UE. The S-GW transmits the downlink data to the UE via
the RAT which has performed the Service Request procedure.
UE
EPC
5) UE triggered Service Request procedure
4) Paging
1) Downlink Data Notification
2) Downlink Data Notification
Acknowledge
3) PAGING
MME
S-GW
Indoor Pico Cell
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