5G • Security
5G-S-TMSI
5G Shortened Temporary Mobile Subscriber Identity
48-bit compact temporary identifier used in radio access signaling (Msg3, Paging) to conserve bandwidth.
Technical Explanation
The 5G-S-TMSI is a shortened 48-bit version of the 5G-GUTI, containing the 8-bit AMF Set ID, 8-bit AMF Pointer, and 32-bit 5G-TMSI. It is transmitted in Msg3 during RRC connection setup and in paging records over the radio interface, saving critical bits while uniquely routing requests to the serving AMF.
Key Functions
- Compact 48-bit temporary identifier for efficient over-the-air signaling
- Contains AMF Set ID, AMF Pointer, and 32-bit 5G-TMSI
- Carried in RRCSetupRequest (Msg3) and Paging records to route to correct AMF
Specifications
3GPP TS 23.501, TS 38.331
Interfaces
Uu
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