known as Reference points according to 3GPP TS 23.501. N3 is the Reference Point between the 5G Access Network and the User Plane Function (UPF) N1 is the Reference Point between UE and the Access and Mobility Management Function (AMF) . It is usually shown as a direct logical connection between the UE and AMF.
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SGi:- It is the reference point between the PDN GW and the packet data network . Packet data network may be an operator external public or private packet data network or an intra operator packet data network, e.g. for provision of IMS services. This reference point corresponds to Gi for 3GPP accesses.
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