5G • RAN
RRC Setup Procedure
RRC Connection Establishment
3-step signaling exchange (Request, Setup, Setup Complete) transitioning UE from RRC_IDLE to RRC_CONNECTED.
Technical Explanation
When initiating a call, data transfer, or registration, the UE transmits RRCSetupRequest on SRB0 via CCCH. The gNodeB replies with RRCSetup on CCCH (establishing SRB1 and initial radio parameters), and the UE confirms with RRCSetupComplete on DCCH, embedding the initial NAS registration or service request message.
Key Functions
- Transitions UE state from RRC_IDLE to RRC_CONNECTED
- Establishes Signaling Radio Bearer 1 (SRB1) for dedicated signaling
- Transfers initial NAS message from UE to 5G Core AMF
Specifications
3GPP TS 38.331
Interfaces
Uu
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