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non access stratum in 5g

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In 5G (Fifth Generation) mobile networks, the architecture is divided into two main layers: the Access Stratum (AS) and the Non-Access Stratum (NAS). The Access Stratum is responsible for handling the radio interface and is closely associated with the radio access network (RAN). On the other hand, the Non-Access Stratum is responsible for managing functions that are independent of the radio interface. Let's delve into the technical details of the Non-Access Stratum (NAS) in 5G.

Non-Access Stratum (NAS) is primarily concerned with the following functionalities:

  1. Mobility Management (MM):
    • Registration and Deregistration: The NAS handles the registration and deregistration procedures when a user equipment (UE) enters or leaves the network. This involves authentication, authorization, and updating the location information.
    • Location Update: The NAS manages the process of updating the UE's location, ensuring that the network is aware of the current location of the device.
  2. Session Management (SM):
    • Attach and Detach Procedures: NAS handles the attach and detach procedures when a UE connects or disconnects from the network. This involves establishing and releasing the data session with the core network.
    • PDU (Packet Data Unit) Session Management: NAS manages the establishment, modification, and release of PDU sessions for data transfer.
  3. Security Control:
    • Authentication and Key Agreement (AKA): NAS is responsible for initiating and managing the AKA process, ensuring secure communication between the UE and the network.
    • Security Mode Control: The NAS controls the establishment and release of security mode procedures to ensure the confidentiality and integrity of user data.
  4. ESM (EPS Session Management):
    • EPS Bearer Control: NAS manages the establishment, modification, and release of EPS bearers, which are logical channels for data transfer between the UE and the core network.
    • Quality of Service (QoS) Handling: NAS is involved in setting up and maintaining the QoS parameters for the user data transfer.
  5. SMS (Short Message Service):
    • SMS Handling: NAS supports the sending and receiving of short messages, including mobile-originated and mobile-terminated SMS.
  6. USSD (Unstructured Supplementary Service Data):
    • USSD Handling: NAS facilitates the exchange of USSD messages between the UE and the core network.

The Non-Access Stratum (NAS) in 5G is responsible for managing mobility, session establishment and release, security, bearer control, SMS, USSD, and other functions that are independent of the radio interface. It ensures the smooth operation and interaction of the user equipment with the core network in a secure and efficient manner.