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5g n26 interface

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The 3GPP (3rd Generation Partnership Project) had defined the specifications for the 5G NR (New Radio) interface, including the N26 interface.

The N26 interface is a reference point in the 5G architecture, and it represents the interface between the gNB (5G NodeB, where "NodeB" is a generic term for a base station) and the AMF (Access and Mobility Management Function). The AMF is part of the 5G core network (5GC) and plays a crucial role in managing the access and mobility aspects of user equipment (UE) in the 5G network.

Here is a technical overview of the N26 interface:

  1. Functionality:
    • The N26 interface is responsible for the transfer of signaling messages between the gNB and the AMF.
    • It handles procedures related to mobility, connection establishment, and management of UE context.
    • N26 supports both control plane signaling and user plane data transfer.
  2. Protocol Stack:
    • The N26 interface uses various protocols to facilitate communication between the gNB and the AMF. These protocols are defined in the 3GPP specifications.
    • For control plane signaling, it uses protocols like NGAP (Next Generation Application Protocol).
    • For user plane data transfer, the N26 interface relies on the GTP (GPRS Tunneling Protocol) or other applicable protocols.
  3. NGAP (Next Generation Application Protocol):
    • NGAP is used for the communication between the gNB and the AMF in the control plane.
    • It is a message-based protocol that supports various procedures such as handover, connection setup and release, and mobility management.
    • NGAP messages are exchanged over SCTP (Stream Control Transmission Protocol) for reliable and connection-oriented communication.
  4. GTP (GPRS Tunneling Protocol):
    • GTP is used for the user plane data transfer between the gNB and the AMF.
    • It facilitates the creation, modification, and deletion of tunnels for transporting user data between the gNB and the AMF.
    • GTP can operate in both control plane (GTP-C) and user plane (GTP-U) modes.
  5. Security:
    • The N26 interface incorporates security mechanisms to ensure the confidentiality, integrity, and authenticity of the transmitted data.
    • Security features include the use of encryption algorithms, integrity protection, and mutual authentication between the gNB and the AMF.
  6. Mobility Management:
    • The N26 interface plays a crucial role in mobility management, allowing the UE to seamlessly move between different gNBs while maintaining an active connection.