Sign in Subscribe

NR-UL NAS Transport

Last updated on 


In 5G (New Radio or NR), NR-UL NAS (Non-Access Stratum) Transport refers to the process of transporting Non-Access Stratum signaling and messages from the User Equipment (UE) to the network during uplink communication. The Non-Access Stratum handles procedures related to the core network functionality, such as mobility management, session management, and network access. Here's a detailed technical explanation of NR-UL NAS Transport:

  1. NAS Message Generation:The NAS layer within the UE generates NAS messages based on the requirements of various procedures, such as attach, detach, registration, authentication, and signaling for mobility.
  2. PDU Session Establishment:When a new PDU (Packet Data Unit) session needs to be established or an existing one needs modification, the NAS layer generates messages for the establishment or modification of the PDU session.
  3. Security Processing:The NAS messages are processed for security, including encryption and integrity protection, ensuring the confidentiality and authenticity of the NAS messages.
  4. RRC (Radio Resource Control):The NAS messages are passed to the RRC layer, which then forwards them to the MAC layer for further processing and encapsulation.
  5. MAC (Medium Access Control) Layer:At the MAC layer, the NAS messages are organized into transport blocks and prepared for transmission. The MAC layer manages the scheduling of transport blocks and controls the information to be transmitted to the base station.
  6. Logical Channels and Transport Channels:Logical channels are mapped to transport channels, which provide specific characteristics like error correction and multiplexing. For NAS transport, the messages are typically mapped to the common control channels like the PUCCH (Physical Uplink Control Channel).
  7. Multiplexing and Modulation:The NAS messages are multiplexed with other information to be transmitted on the uplink. The multiplexed data is then modulated (e.g., QPSK, 16-QAM, 64-QAM) based on the channel conditions and requirements.
  8. Transmission:The UE transmits the modulated NAS messages over the specified channel (e.g., PUCCH) using the allocated resources. The transmission adheres to the scheduled plan determined by the base station.
  9. Decoding at the Base Station:The base station receives the transmitted NAS messages, demodulates, and decodes them to obtain the original NAS messages sent by the UE.
  10. Processing at the Core Network:The base station forwards the received NAS messages to the core network, where they are further processed based on the specific procedure they pertain to (e.g., authentication, session management, mobility management).

In summary, NR-UL NAS Transport involves generating, securing, and transmitting NAS messages from the UE to the core network over the uplink. This process is vital for communication between the UE and the network for various core network functionalities in a 5G environment.