Process of 5G NR SA Registration [PART-1]

  • The first step in 5G Standalone (SA) call processing is synchronization between UE and gNB.

  • The synchronization process is divided into Downlink synchronization and Uplink synchronization.

  • Downlink synchronization precedes Uplink synchronization.

Downlink Synchronization:

  • UE performs cell search for synchronization signals.
  • Primary Synchronization Signal (PSS) and Secondary Synchronization Signal (SSS) are acquired.
  • PSS and SSS help identify the cell and synchronize UE’s timing.

Uplink Synchronization:

  • Uplink synchronization achieved through RACH Process.
  • Random Access Channel (RACH) is used for initial uplink synchronization.
  • UE transmits a randomly chosen preamble via RACH.
  • gNB detects preamble and responds with timing adjustment.
  • This process aligns UE’s transmission timing with gNB for efficient communication.

RRC Connection Establishment:

  • Post synchronization, UE initiates Radio Resource Control (RRC) connection procedure.
  • UE sends RRCSetupRequest message to gNB.
    · gNB responds with RRCSetup message containing vital configuration details.
  • Configuration information facilitates UE’s access to network resources.

Registration Request:

  • After successful RRC connection establishment,
  • UE sends Registration Request message to Core Network (AMF).
  • Purpose is to register with 5G network.
  • Message includes significant details:
    UE’s security credentials
    UE’s network capability.

Note: It is a simplified call processing/Signaling flow of SA Initial Attach process[PART1], if you want to understand the in-depth flow analysis then i do recommend to refer Event Helix, Links mentioned in comment section.

Process of 5G NR SA Registration [PART-1]

LinkedIn: :point_down: