5G Notes Series AMF

5G-Series
notes
Quick notes on 5GC NFs
Published

April 25, 2023

AMF => Access & Mobility Function

  • AMF <-> gNodeB via N2 interface
  • AMF <-> UE via N1 interface
    • AMF is the MME equivalent as in LTE, but in LTE there is direct interface between MME and UE
    • N1 is happening via gNodeB but gNodeB acts as transparent proxy for N1
  • AMF <-> SMF for session management
  • AMF <-> LMF for location management
  • AMF <-> PCF for policy enforcement
  • AMF <-> AUSF/UDF for Authentication & Subscriber management
    • AMF acts as a relay between xNF and UE for all session related signalling
      • xNF -> AMF -> gNodeB -> UE
  • Incase of 5G NSA (Non Stand Alone) and interworking with EPC, AMF connects to MME for sharing of user contexts incase UE moves between 5GC and EPC
    • Less signalling and no need for reauthentication

UE <-> AMF Registration Mgmt States

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