5G/NR - NAS            






5GMM(5G Mobility Management)


5G Mobile Management is involved mainly in NAS registration process and in terms of corenetwork interface point of view, it is mostly associated with N1/N2 interface. Some of the major functionality of 5GMM is as follows (as described in 24.501-5.1.2) .


  • registration
  • de-registration
  • eCall inactivity procedure
  • connected mode procedure
    • network-initiated NAS transport
    • primary authentication and key agreement procedure
    • security mode control
    • generic UE configuration update
    • identification
    • UE-initiated NAS transport
  • connection management procedure
    • service request
    • paging
    • notification




5GMM Statemachine


5GMM is very complicated process described in about 150 pages in 24.501 and you would easily get lost if you directly jumping into reading the details. My recommendation is to try to get familiar with the following statemachine to the point where you can draw the statemachine by hands and then read the specification as-you-need basis.



< 24.501 Figure 5GMM main states in the UE >




< 24.501 Figure 5GMM main states in the network >





NAS Signaling Procedures Handled by 5GMM


Followings are the list of NAS signaling (OTA procedure) handled by 5GMM. I think these message (process) list would give more concrete idea to most of the readers since analyzing OTA message would be pretty common practice. I will create separate notes for each of these process and put the link as I complete the note... but not sure how long it will take to complete all of them, but I will try to complete at least 5G specific process as early as possible. For most of other procedures, I think you can apply your LTE knowledge. Each of NAS messages involved in each of these procedures are described in 24.501-8.2.


  • Authentication
  • Registration
  • UL/DL NAS Transport
  • De-Registration
  • Service Setup
  • Configuration Update
  • Identify Query
  • Notification
  • Security Mode Setup
  • 5GMM Status