Simplified Call Flow Signaling: Registration - The Attach Procedure
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The document outlines the registration and attach procedure in 2G, 3G, and 4G network architectures, focusing on the signaling process between the user equipment (UE) and core networks. It describes how a UE notifies the core networks of its activation, the identity management, and the necessary authentication steps. Additionally, it emphasizes the use of temporary identities for privacy and security during the registration process.
Simplified Call Flow Signaling: Registration - The Attach Procedure
- 1. Simplified Call Flow Signaling: Registration - The Attach Procedure @3g4gUK
- 2. 2G/3G/4G Network Architecture ©3G4G BSC BTS MSC Voice (PSTN) Network SGSN Data (IP) Network RNC Node BeNodeB MME GGSN Access Network Core Network Air Interface MSUEUE BSSRNS S-GW P-GW 2G 2.5G 3G 4G EPC
- 3. Simplified Network Architecture ©3G4G AS CS NAS Voice (PSTN) Network Data (IP) Network Device / UE Radio Access Network Core Network Air Interface NAS = Non Access Stratum AS = Access Stratum UE = User Equipment PS NAS Backhaul AS
- 4. Registration ©3G4G • The device or UE needs to let the core network(s) know that it is switched on and active. • This procedure is known as registration • The UE can register individually to the CS and PS core networks • Most modern networks allow combined registration (or combined attach) whereby the UE registers only to the PS network and the PS network informs the CS network that the UE is active.
- 5. Simplified Network Architecture ©3G4G AS CS NAS Voice (PSTN) Network Data (IP) Network Device / UE Radio Access Network Core Network Air Interface NAS = Non Access Stratum AS = Access Stratum UE = User Equipment PS NAS Backhaul AS
- 6. Simplified Network Architecture ©3G4G AS CS NAS Voice (PSTN) Network Data (IP) Network Device / UE Radio Access Network Core Network Air Interface NAS = Non Access Stratum AS = Access Stratum UE = User Equipment PS NAS Backhaul AS
- 7. Identities ©3G4G • Each Mobile device contain IMEI (International Mobile Equipment Identity) • The SIM (Subscriber Identity Module) contains: • IMSI – International Mobile Subscriber Identity • MSISDN – Mobile Subscriber ISDN number • Secret keys for Authentication with the network • During operation, the mobile uses temporary identity called TMSI so that no one can find the true identity of a mobile.
- 8. The Attach Procedure Signalling ©3G4G UE AN CS CN PS CN Access Network Core Network Primary Synchronisation Channel / Signal Secondary Synchronisation Channel / Signal Other Downlink Reference Signals (4G / LTE Only)
- 9. The Attach Procedure Signalling ©3G4G UE AN CS CN PS CN Access Network Core Network PS CN broadcast information CS CN broadcast information System information messages
- 10. The Attach Procedure Signalling ©3G4G UE AN CS CN PS CN Access Network Core Network PS CN broadcast information CS CN broadcast information System information messages Hello, I am UE 1
- 11. The Attach Procedure Signalling ©3G4G UE AN CS CN PS CN Access Network Core Network PS CN broadcast information CS CN broadcast information System information messages Hello, I am UE 1 Hello UE1, please use this channel <…> Thanks, I am all setup.
- 12. The Attach Procedure Signalling ©3G4G UE AN CS CN PS CN Access Network Core Network PS CN broadcast information CS CN broadcast information System information messages Hello, I am UE 1 Hello UE1, please use this channel <…> Thanks, I am all setup. Hello, I am UE 1. Want to Attach and let you know that I am now active Hello UE 1, please authenticate yourself against this vector <…>
- 13. HLR, HSS & AuC ©3G4G • HLR – Home Location Register • HSS – Home Subscriber Server • AuC – Authentication Center 4G PS Core Network 2G/3G PS Core Network 2G/3G CS Core Network HLR/HSS/AuC DATA Logic
- 14. The Attach Procedure Signalling ©3G4G UE AN CS CN PS CN Access Network Core Network PS CN broadcast information CS CN broadcast information System information messages Hello, I am UE 1 Hello UE1, please use this channel <…> Thanks, I am all setup. Hello, I am UE 1. Want to Attach and let you know that I am now active Hello UE 1, please authenticate yourself against this vector <…> No problems, here is my authentication response <…>
- 15. The Attach Procedure Signalling ©3G4G UE AN CS CN PS CN Access Network Core Network I trust UE1, please establish security with it Establish Security using <…> Thanks, all done. Security Established
- 16. The Attach Procedure Signalling ©3G4G UE AN CS CN PS CN Access Network Core Network I trust UE1, please establish security with it Establish Security using <…> Thanks, all done. Security Established Attach Accept. Please use this new temporary identity for now Attach Complete.
- 17. The Attach Procedure Signalling ©3G4G UE AN CS CN PS CN Access Network Core Network UE1 is now connected to us I trust UE1, please establish security with it Establish Security using <…> Thanks, all done. Security Established Attach Accept. Please use this new temporary identity for now Attach Complete.
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