User's Manual

Ver.
CHAPTER 4. Message Flow
2600-00FKQFGA2
1.0
Step Description
1)
The UE performs the random access procedure with the Indoor Pico Cell.
2)~4) The UE includes the SERVICE REQUEST message (NAS) in the RRC message
transmitted to the Indoor Pico Cell and transmits it to the MME.
5) The Indoor Pico Cell includes the SERVICE REQUEST message in the INITIAL UE
message, which is an S1-AP message, and transmits it to the MME.
6) If there is no UE context for the UE in the network, integrity is not protected for the
ATTACH REQUEST message, or the integrity check fails, authentication and NAS
security setup are always performed.
The UE performs the EPS authentication and key agreement (AKA) procedure (TS
33.401, 6.1.1) with the MME. The MME sets up an NAS security association with the
UE using the NAS security mode command (SMC) procedure (TS 33.401, 7.2.4.4).
7) The MME transmits the S1-AP Initial Context Setup Request message to the Indoor
Pico Cell.
In this step, radio and S1 bearer are activated for all activated EPS bearers.
8)~11)
The Indoor Pico Cell sets up the RRC radio bearers. The user plane security is set up at
this step. The uplink data transmitted by the UE is relayed from the Indoor Pico Cell to
the S-GW. The Indoor Pico Cell transmits the uplink data to the S-GW, and then the S-
GW transmits it to the P-GW.
12) The Indoor Pico Cell transmits the S1-AP Initial Context Setup Request message to the
MME.
13)~14) The MME transmits the Modify Bearer Request message for each PDN connection to
the S-GW.
Now, the S-GW can transmit the downlink data to the UE. The S-GW transmits the
Modify Bearer Response message to the MME.
© SAMSUNG Electronics Co., Ltd.
page 51 of 72