User's Manual

Ver.
CHAPTER 4. Message Flow
2600-00FKQFGA2
1.0
Step Description
1) The UE transmits the MessurementReport message according to the system
information, standards and rules. The source Indoor Pico Cell determines whether to
perform the UE handover based on the MeasurementReport message and the radio
resource management information.
2) The source Indoor Pico Cell transmits the HANDOVER REQUEST message and the
information required for handover to the target Indoor Pico Cell. The target Indoor Pico
Cell can perform management control in accordance with the E-RAB QoS information
received.
3)~4) The target Indoor Pico Cell creates the RRCConnectionReconfiguration message which
contains the mobileControlInfo IE for preparing and executing the handover. The target
Indoor Pico Cell includes the RRCConnectionReconfiguration message in the
HANDOVER REQUEST ACKNOWLEDGE message, and transmits it to the source
Indoor Pico Cell.
The source Indoor Pico Cell transmits the RRCConnectionReconfiguration message
and the necessary parameters to the UE to command it to perform the handover.
5) To transmit the uplink PDCP SN receiver status and the downlink PDCP SN transmitter
status of the E-RABs of which the PDCP status must be preserved, the source Indoor
Pico Cell transmits the SN STATUS TRANSFER message to the target Indoor Pico Cell.
6) After receiving the RRCConnectionReconfiguration message containing
mobileControlInfo IE, the UE performs synchronization with the target Indoor Pico Cell
and connects to the target cell via a RACH. The target Indoor Pico Cell responds with
UL allocation and a timing advance value.
7) After successfully connecting to the target cell, the UE uses the RRCConnection-
ReconfigurationComplete message to notify the target Indoor Pico Cell that the
handover procedure is complete.
8) The target Indoor Pico Cell uses the PATH SWITCH REQUEST message to notify the
MME that the UE has changed the cell.
9)~10) The MME transmits the Modify Bearer Response message to the S-GW. The S-GW
changes the downlink data path into the target Indoor Pico Cell. The S-GW transmits at
least one ‘end marker’ to the source Indoor Pico Cell through the previous path, and
releases the user plane resources for the source Indoor Pico Cell.
The S-GW transmits the Modify Bearer Response message to the MME.
11) The MME transmits the PATH SWITCH REQUEST ACKNOWLEDGE message to
acknowledge the PATH SWITCH REQUEST message.
12) The target Indoor Pico Cell transmits the UE CONTEXT RELEASE message to the
source Indoor Pico Cell to notify the handover has succeeded and to make the source
Indoor Pico Cell release its resources. If the source Indoor Pico Cell receives the UE
CONTEXT RELEASE message, it releases the radio resources and the control plane
resources related to the UE context.
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